Sample records for turbulent circular jet

  1. Modeling of NOx formation in circular laminar jet flames

    E-Print Network [OSTI]

    Siwatch, Vivek

    2007-04-25T23:59:59.000Z

    -premixed isolated circular laminar jet flame. The jet consists of the fuel rich inner region and the O2 rich outer region. The model estimates both thermal NOx and prompt NOx assuming single step kinetics for NOx formation and a thin flame model. Further the amount...

  2. Can Protostellar Jets Drive Supersonic Turbulence in Molecular Clouds?

    E-Print Network [OSTI]

    Robi Banerjee; Ralf S. Klessen; Christian Fendt

    2007-06-25T23:59:59.000Z

    Jets and outflows from young stellar objects are proposed candidates to drive supersonic turbulence in molecular clouds. Here, we present the results from multi-dimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with velocity probability density functions. Our study include jet--clump interaction, transient jets, and magnetised jets. We find that collimated supersonic jets do not excite supersonic motions far from the vicinity of the jet. Supersonic fluctuations are damped quickly and do not spread into the parent cloud. Instead subsonic, non-compressional modes occupy most of the excited volume. This is a generic feature which can not be fully circumvented by overdense jets or magnetic fields. Nevertheless, jets are able to leave strong imprints in their cloud structure and can disrupt dense clumps. Our results question the ability of collimated jets to sustain supersonic turbulence in molecular clouds.

  3. Turbulent round jet under gravity waves

    E-Print Network [OSTI]

    Ryu, Yong Uk

    2002-01-01T23:59:59.000Z

    ) Turbulent shear stress &u'w'&/&u, & versus z/x. . . 26 3-5 Overlapped mean axial velocity &u&/&u, & versus zJx of the case of A = 0. 5 cm at six locations corresponding to figure 3-4(a) . . 28 3-6 Horizontal turbulent velocity &u' &' /&u, & versus zJx... of the case of A = 0. 5 cm with z, = 0 at. the moving jet centerline in the range of (a) x/D = 40 - 95, (b) x/D = 40 ? 57, and (c) x/D = 64 - 95 . . 30 3-7 Vertical turbulent velocity &w' & /&u, & versus z Jx of the case of A = 0. 5 cm FIGURE Page with z...

  4. Numerical simulation of turbulent jet primary breakup in Diesel engines

    E-Print Network [OSTI]

    Helluy, Philippe

    Numerical simulation of turbulent jet primary breakup in Diesel engines Peng Zeng1 Marcus Herrmann" IRMA Strasbourg, 23.Jan.2008 #12;Introduction DNS of Primary Breakup in Diesel Injection Phase Transition Modeling Turbulence Modeling Summary Outline 1 Introduction 2 DNS of Primary Breakup in Diesel

  5. Dynamics of quasi-two-dimensional turbulent jets

    E-Print Network [OSTI]

    Landel, Julien Rémy Dominique Gérard

    2012-11-13T23:59:59.000Z

    In turbulent jets, fluid is driven by momentum from an orifice into an environ- ment filled with similar fluid. The complexity of this flow, which has been studied for more than 80 years (see e.g. List, 1982, for a detailed review), resides in its turbulent... in time with an accuracy of approximately 1 %. We conducted two distinct sets of experiments using two qualitatively different techniques: dye tracking and particle image velocimetry (PIV). 7 2 Meandering and self-similarity of quasi-two-dimensional jets x...

  6. An experimental study of jet impingement on a circular cylinder

    E-Print Network [OSTI]

    Potts, Dennis Wayne

    2012-06-07T23:59:59.000Z

    diameter of 6 5/8 inches. The jet was impinged upon the cylinder at nozzle distances of 7, 15, and 30 nozzle diameters, and at velocities of' 400 and 500 ft/s. The free jet was studied and found to be "typical" by comparing it to earlier studies done... Instrumentation schematic 17 5 Cylindrical suriace coordinate system 22 6 Photograph of the cylinder with "grid" 23 7 Photograph of the wall jet traversing apparatus 24 8 Orientation of the hot film sensor 25 9 Free jet geometry and parameters 30 10 Velocity...

  7. Oscillations of a Turbulent Jet Incident Upon an Edge

    SciTech Connect (OSTI)

    J.C. Lin; D. Rockwell

    2000-09-19T23:59:59.000Z

    For the case of a jet originating from a fully turbulent channel flow and impinging upon a sharp edge, the possible onset and nature of coherent oscillations has remained unexplored. In this investigation, high-image-density particle image velocimetry and surface pressure measurements are employed to determine the instantaneous, whole-field characteristics of the turbulent jet-edge interaction in relation to the loading of the edge. It is demonstrated that even in absence of acoustic resonant or fluid-elastic effects, highly coherent, self-sustained oscillations rapidly emerge above the turbulent background. Two clearly identifiable modes of instability are evident. These modes involve large-scale vortices that are phase-locked to the gross undulations of the jet and its interaction with the edge, and small-scale vortices, which are not phase-locked. Time-resolved imaging of instantaneous vorticity and velocity reveals the form, orientation, and strength of the large-scale concentrations of vorticity approaching the edge in relation to rapid agglomeration of small-scale vorticity concentrations. Such vorticity field-edge interactions exhibit rich complexity, relative to the simplified pattern of vortex-edge interaction traditionally employed for the quasi-laminar edgetone. Furthermore, these interactions yield highly nonlinear surface pressure signatures. The origin of this nonlinearity, involving coexistence of multiple frequency components, is interpreted in terms of large- and small-scale vortices embedded in distributed vorticity layers at the edge. Eruption of the surface boundary layer on the edge due to passage of the large-scale vortex does not occur; rather apparent secondary vorticity concentrations are simply due to distension of the oppositely-signed vorticity layer at the tip of the edge. The ensemble-averaged turbulent statistics of the jet quickly take on an identity that is distinct from the statistics of the turbulent boundary layer in the channel. Large increases in Reynolds stress occur due to onset of the small-scale concentrations of vorticity immediately downstream of separation; substantial increases at locations further downstream arise from development of the large-scale vorticity concentrations.

  8. Investigation of the effect of a circular patch of vegetation on turbulence generation and sediment deposition using four case studies

    E-Print Network [OSTI]

    Ortiz, Alejandra C

    2012-01-01T23:59:59.000Z

    This study describes the spatial distribution of sediment deposition in the wake of a circular patch of model vegetation and the effect of the patch on turbulence and mean flow. Two difference types pf vegetation were used ...

  9. The use of turbulent jets to destratify the Charles River Basin

    E-Print Network [OSTI]

    Church, Jeffrey H. (Jeffrey Harrison)

    2012-01-01T23:59:59.000Z

    This study examines the feasibility of using turbulent jets to destratify the Lower Charles River Basin between the Longfellow and Craigie Bridges between Boston and Cambridge. The basin is currently filled with salt water ...

  10. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    SciTech Connect (OSTI)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard [Institute of Fluid Dynamics, ETH Zurich, 8092 Zurich (Switzerland)

    2014-08-15T23:59:59.000Z

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re{sub D} = 18?100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

  11. An evaluation of linear instability waves as sources of sound in a supersonic turbulent jet

    E-Print Network [OSTI]

    Dabiri, John O.

    An evaluation of linear instability waves as sources of sound in a supersonic turbulent jet Kamran 2002; published 5 September 2002 Mach wave radiation from supersonic jets is revisited to better justification of the linear theory. However, it is found that the sound pressure level predicted by LNS

  12. Large-scale eddies and their role in entrainment in turbulent jets and wakes Jimmy Philip and Ivan Marusic

    E-Print Network [OSTI]

    Marusic, Ivan

    Large-scale eddies and their role in entrainment in turbulent jets and wakes Jimmy Philip and Ivan jets and wakes Jimmy Philipa) and Ivan Marusicb) Department of Mechanical Engineering, University

  13. CONTROL OF COHERENT STRUCTURE IN COAXIAL SWIRLING TURBULENT JETS

    E-Print Network [OSTI]

    Lee, Wonjoong

    2008-01-01T23:59:59.000Z

    .............................................................. 193 xvi NOMENCLATURE Symbol Description Unit D Jet diameter, Defined in Figure 5.1 m D h Hydraulic jet diameter m f Excitation frequency s -1 G Degree of swirl, Defined... stronger effect than the pilot jet itself, leading to an almost entire removal of coherent structures. 2.2. Flow Instability Swirl is naturally presented in the exhaust from a turbine or an axial flow pump, and may be deliberately generated...

  14. Characterization of turbulent jet mixing in cylindrical tanks

    E-Print Network [OSTI]

    Schulte, Casey M

    1998-01-01T23:59:59.000Z

    , for the most part, confirms many of the findings of previous studies of jet mixing. First, mixing time in jet-mixed systems depends primarily upon the mass of the fluid in a tank and the amount of addition, to maximize the efficient transfer of momentum...

  15. Magnetohydrodynamic lattice Boltzmann simulations of turbulence and rectangular jet flow

    E-Print Network [OSTI]

    Riley, Benjamin Matthew

    2009-05-15T23:59:59.000Z

    relaxation time (SRT) parameter for the Maxwell’s stress tensor is developed for this study. In the MHD homogeneous turbulence studies, the kinetic/magnetic energy and enstrophy decays, kinetic enstrophy evolution, and vorticity alignment with the strain...

  16. Pdf modeling of turbulent nonpremixed methane jet flames

    SciTech Connect (OSTI)

    Chen, J.Y.; Kollmann, W.; Dibble, R.W. (Sandia National Labs., Livermore, CA (USA). Combustion Research Faclity)

    1989-01-01T23:59:59.000Z

    An expanded model of turbulent nonpremixed combustion is presented. In the model, the scalar mixing and reactions are described by a probability density function (pdf) submodel capable of handling five scalars, while the turbulent velocity field is described by a second-order moment closure. Two plausible chemical reaction models are considered: a five-scalar, four-step, reduced reaction mechanism, and a four-scalar constrained equilibrium model. Detailed comparisons of model predictions with laser Raman experimental dat provide a valuable evaluation of the model's ability in predicting nonequilibrium chemistry in turbulent nonpremixed flames. Overall, the model fails to predict greater departure from chemical equilibrium as mixing rates are increased. Interestingly, this failure is not due to the chemical model, both of which perform satisfactorily. Instead, the failure to predict greater departure from chemical equilibrium is a subtle artifact of the current Monte Carlo simulation of turbulent mixing and chemical reaction.

  17. Turbulent fluid jet excavation in cohesive soil : with particular application to jet grouting

    E-Print Network [OSTI]

    Ho, Chu Eu

    2005-01-01T23:59:59.000Z

    This thesis reviews the jet grouting methodology, and the current state of practice and research. Current methods of prediction of jet grout diameters are highly empirical and site specific, and do not take into account ...

  18. Validation Analysis for the Calculation of a Turbulent Free Jet in Water Using CFDS-FLOW 3-D and FLUENT

    SciTech Connect (OSTI)

    Dimenna, R.A.; Lee, S.Y.

    1995-05-01T23:59:59.000Z

    The application of computational fluid dynamics methods to the analysis of mixing in the high level waste tanks at the Savannah River Site requires a demonstration that the computer codes can properly represent the behavior of fluids in the tanks. The motive force for mixing the tanks is a set of jet pumps taking suction from the tank fluid and discharging turbulent jets near the bottom of the tank. The work described here focuses on the free turbulent jet in water as the simplest case of jet behavior for which data could be found in the open literature. Calculations performed with both CFDS-FLOW3D and FLUENT were compared with data as well as classical jet theory. Results showed both codes agreed reasonably well with each other and with the data, but that results were sensitive to the computational mesh and, to a lesser degree, the selection of turbulence models.

  19. Understanding and predicting soot generation in turbulent non-premixed jet flames.

    SciTech Connect (OSTI)

    Wang, Hai (University of Southern California, Los Angeles, CA); Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01T23:59:59.000Z

    This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model to accurately predict gas temperatures and thus soot formation rates. When including such a radiation model, the LES model predicts mean soot concentrations within 30% in the ethylene jet flame.

  20. A theoretical and numerical investigation of turbulent steam jets in BWR steam blowdown.

    SciTech Connect (OSTI)

    NguyenLe, Q.

    1998-06-26T23:59:59.000Z

    The preliminary results of PHOENICS and RELAP5 show that the current numerical models are adequate in predicting steam flow and stratification patterns in the upper Drywell of a BWR containment subsequent to a blow-down event. However, additional modeling is required in order to study detailed local phenomena such as condensation with non-condensables, natural convection, and stratification effects. Analytically, the intermittence modified similarity solutions show great promise. Once {gamma} is accounted for, the jet's turbulent shear stress can be determined with excellent accuracy.

  1. Triple Cascade Behavior in Quasigeostrophic and Drift Turbulence and Generation of Zonal Jets

    SciTech Connect (OSTI)

    Nazarenko, Sergey; Quinn, Brenda [Mathematics Institute, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom)

    2009-09-11T23:59:59.000Z

    We study quasigeostrophic (QG) and plasma drift turbulence within the Charney-Hasegawa-Mima (CHM) model. We focus on the zonostrophy, an extra invariant in the CHM model, and on its role in the formation of zonal jets. We use a generalized Fjoertoft argument for the energy, enstrophy, and zonostrophy and show that they cascade anisotropically into nonintersecting sectors in k space with the energy cascading towards large zonal scales. Using direct numerical simulations of the CHM equation, we show that zonostrophy is well conserved, and the three invariants cascade as predicted by the Fjoertoft argument.

  2. Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets

    E-Print Network [OSTI]

    Pouransari, Z; Johansson, A V

    2015-01-01T23:59:59.000Z

    The concept of local isotropy in a chemically reacting turbulent wall-jet flow is addressed using direct numerical simulation (DNS) data. Different DNS databases with isothermal and exothermic reactions are examined. The chemical reaction and heat release effects on the turbulent velocity, passive scalar and reactive species fields are studied using their probability density functions (PDF) and higher order moments for velocities and scalar fields, as well as their gradients. With the aid of the anisotropy invariant maps for the Reynolds stress tensor the heat release effects on the anisotropy level at different wall-normal locations are evaluated and found to be most accentuated in the near-wall region. It is observed that the small-scale anisotropies are persistent both in the near-wall region and inside the jet flame. Two exothermic cases with different Damkohler number are examined and the comparison revealed that the Damkohler number effects are most dominant in the near-wall region, where the wall cooli...

  3. Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets

    E-Print Network [OSTI]

    Z. Pouransari; L. Biferale; A. V. Johansson

    2015-02-21T23:59:59.000Z

    The concept of local isotropy in a chemically reacting turbulent wall-jet flow is addressed using direct numerical simulation (DNS) data. Different DNS databases with isothermal and exothermic reactions are examined. The chemical reaction and heat release effects on the turbulent velocity, passive scalar and reactive species fields are studied using their probability density functions (PDF) and higher order moments for velocities and scalar fields, as well as their gradients. With the aid of the anisotropy invariant maps for the Reynolds stress tensor the heat release effects on the anisotropy level at different wall-normal locations are evaluated and found to be most accentuated in the near-wall region. It is observed that the small-scale anisotropies are persistent both in the near-wall region and inside the jet flame. Two exothermic cases with different Damkohler number are examined and the comparison revealed that the Damkohler number effects are most dominant in the near-wall region, where the wall cooling effects are influential. In addition, with the aid of PDFs conditioned on the mixture fraction, the significance of the reactive scalar characteristics in the reaction zone is illustrated. We argue that the combined effects of strong intermittency and strong persistency of anisotropy at the small scales in the entire domain can affect mixing and ultimately the combustion characteristics of the reacting flow.

  4. Stabilization of turbulent lifted jet flames assisted by pulsed high voltage discharge

    SciTech Connect (OSTI)

    Criner, K.; Cessou, A.; Louiche, J.; Vervisch, P. [CORIA UMR 6614 CNRS-Universite et INSA de Rouen, University of Rouen, 76801 Saint Etienne du Rouvray (France)

    2006-01-01T23:59:59.000Z

    To reduce fuel consumption or the pollutant emissions of combustion (furnaces, aircraft engines, turbo-reactors, etc.), attempts are made to obtain lean mixture combustion regimes. These lead to poor stability of the flame. Thus, it is particularly interesting to find new systems providing more flexibility in aiding flame stabilization than the usual processes (bluff-body, stabilizer, quarl, swirl, etc.). The objective is to enlarge the stability domain of flames while offering flexibility at a low energy cost. Evidence is presented that the stabilization of a turbulent partially premixed flame of more than 10 kW can be enhanced by pulsed high-voltage discharges with power consumption less than 0.1% of the power of the flame. The originality of this work is to demonstrate that very effective stabilization of turbulent flames is obtained when high-voltage pulses with very short rise times are used (a decrease by 300% in terms of liftoff height for a given exit jet velocity can be reached) and to provide measurements of minimum liftoff height obtained with discharge over a large range of the stability domain of the lifted jet flame.

  5. Measurement of turbulent flow upstream and downstream of a circular pipe bend

    SciTech Connect (OSTI)

    Sakakibara, Jun; Machida, Nobuteru [Department of Engineering Mechanics and Energy, University of Tsukuba, Tsukuba 305-8573 (Japan)

    2012-04-15T23:59:59.000Z

    We measured velocity distribution in cross sections of a fully developed turbulent pipe flow upstream and downstream of a 90 degree sign bend by synchronizing two sets of a particle image velocimetry (PIV) system. Unsteady undulation of Dean vortices formed downstream from the bend was characterized by the azimuthal position of the stagnation point found on the inner and outer sides of the bend. Linear stochastic estimation was applied to capture the upstream flow field conditioned by the azimuthal location of the stagnation point downstream from the bend. When the inner-side stagnation point stayed below (above) the symmetry plane, the conditional streamwise velocity upstream from the bend exhibited high-speed streaks extended in a quasi-streamwise direction on the outer side of the curvature above (below) the symmetry plane.

  6. The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Third quarterly technical report, July 1, 1993--September 30, 1993

    SciTech Connect (OSTI)

    Mansour, A.; Chigier, N.

    1993-12-01T23:59:59.000Z

    Laminar and turbulent columns of liquids issuing from capillary tubes were studied in order to determine the effects of turbulence on the stability of liquid jets and to establish the influence of liquid turbulence on droplet size distributions after breakup. Two capillary tubes were chosen with diameters D{sub 1}=3.0mm and D{sub 2}=1.2mm; jet Reynolds numbers were 1000--30000, and 400--7200. For water injection into stagnant air, stability curve is bounded by a laminar portion, where a jet radius and {delta}{sub o} initial disturbance amplitude, and a fully developed turbulent portion characterized by high initial disturbance amplitude (ln(a/{delta}{sub o,T}) {approximately} 4.85). In the transition region, ln(a/{delta}{sub o}) is not single valued; it decreases with increasing Reynolds number. In absence of aerodynamic effects, turbulent jets are as stable as laminar jets. For this breakup mode turbulence propagates initial disturbances with amplitudes orders of magnitude larger than laminar jets ({delta}{sub o,T}=28{times}10{sup 6} {delta}{sub o,L}). Growth rates of initial disturbances are same for both laminar and turbulent columns with theoretical Weber values. Droplet size distribution is bi-modal; the number ratio of large (> D/2), to small (< D/2) droplets is 3 and independent of Reynolds number. For laminar flow optimum wavelength ({lambda}{sub opt}) corresponding to fastest growing disturbance is equal to 4.45D, exactly the theoretical Weber value. For turbulent flow conditions, the turbulent column segments. Typically, segments with lengths of one to several wavelengths, detach from the liquid jet. The long ligaments contract under the action of surface tension, resulting in droplet sizes larger than predicted by Rayleigh and Weber. For turbulent flow conditions, {lambda}{sub opt} = 9.2D, about 2 times the optimum Weber wavelength.

  7. HPC realization of a controlled turbulent round jet using OpenFOAM

    E-Print Network [OSTI]

    Önder, Asim

    2014-01-01T23:59:59.000Z

    The present paper investigates high performance computing abilities of OpenFOAM for a low Reynolds number ($Re_D=2000$) axisymmetric jet subject to multiple zero net mass flux (ZNMF) actuators. First, parallel performance of OpenFOAM is tested by performing a scaling study up to $2048$ processors on a supercomputer of Flemish Supercomputer Center(VSC). Then, a method to improve the parallel efficiency is proposed. The method is based on developing a hybrid concept to calculate the statistical moments. This new concept combines ensemble and time averaging in order to allow data sampling in parallel. The motivation is obtaining a reduction in the walltime to collect turbulent statistics which is observed to be the dominating part in the ZNMF controlled jet flow. Employing this parallel statistical averaging approach in combination with regular grid partitioning parallelism, allowed us conducting DNS cases on $P=624$ processors with an overall speed-up of $S_e=540.56$ and a parallel efficiency of $E_e=0.87$. The...

  8. Large eddy simulation of soot formation in a turbulent non-premixed jet flame

    SciTech Connect (OSTI)

    El-Asrag, Hossam [Center For Turbulence Research, Stanford, CA 94305 (United States); Menon, Suresh [School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2009-02-15T23:59:59.000Z

    A recently developed subgrid model for soot dynamics [H. El-Asrag, T. Lu, C.K. Law, S. Menon, Combust. Flame 150 (2007) 108-126] is used to study the soot formation in a non-premixed turbulent flame. The model allows coupling between reaction, diffusion and soot (including soot diffusion and thermophoretic forces) processes in the subgrid domain without requiring ad hoc filtering or model parameter adjustments. The combined model includes the entire process, from the initial phase, when the soot nucleus diameter is much smaller than the mean free path, to the final phase, after coagulation and aggregation, where it can be considered in the continuum regime. A relatively detailed but reduced kinetics for ethylene-air is used to simulate an experimentally studied non-premixed ethylene/air jet diffusion flame. Acetylene is used as a soot precursor species. The soot volume fraction order of magnitude, the location of its maxima, and the soot particle size distribution are all captured reasonably. Along the centerline, an initial region dominated by nucleation and surface growth is established followed by an oxidation region. The diffusion effect is found to be most important in the nucleation regime, while the thermophoretic forces become more influential downstream of the potential core in the oxidation zone. The particle size distribution shows a log-normal distribution in the nucleation region, and a more Gaussian like distribution further downstream. Limitations of the current approach and possible solution strategies are also discussed. (author)

  9. Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

    SciTech Connect (OSTI)

    Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

    2012-01-01T23:59:59.000Z

    Turbulent CO/H{sub 2}/N{sub 2} (“syngas”) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k–? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulence–chemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

  10. Simulation of turbulent lifted methane jet flames: effects of air-dilution and transient flame propagation

    E-Print Network [OSTI]

    Chen, Z.; Ruan, S.; Swaminathan, N.

    2014-10-03T23:59:59.000Z

    + (ZO,2 ? ZO)/WO 2ZC,1/WC ? ZO,1/WO + ZH,1/2 WH + ZO,2/WO . (10) The mass fraction of an element i and its atomic mass are denoted as Zi and Wi re- spectively. Here, carbon, hydrogen and oxygen elements are used. The subscripts 1 and 2 denote the fuel... unstructured grid with fine mesh near the jet exit to resolve large spatial gradients in the near field of the fuel jet. A typical grid used for simula- tions is shown in Fig. 1b and it consists of 76,648 cells with the smallest size of 0.5 mm (0.1dj...

  11. Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model

    E-Print Network [OSTI]

    Chien, Li-Chun

    2010-01-01T23:59:59.000Z

    turbulence model for a syngas jet flame. Proceeding of FallKerstein 2002), a turbulent syngas (CO/H2/NO) jet flame wasand DNS results of the syngas jet flame was recently done

  12. An analytical investigation of primary zone combustion temperatures and NOx production for turbulent jet flames using low-BTU fuels

    E-Print Network [OSTI]

    Carney, Christopher Mark

    1995-01-01T23:59:59.000Z

    The objective of this research project was to identify and determine the effect of jet burner operating variables that influence combustion of low-BTU gases. This was done by simulating the combustion of a low-BTU fuel in a jet flame and predicting...

  13. Rossby waves and two-dimensional turbulence in the presence of a large-scale zonal jet

    E-Print Network [OSTI]

    Shepherd, Theodore Gordon

    1984-01-01T23:59:59.000Z

    This dissertation represents a theoretical, numerical, and observational study of barotropic waves and turbulence in an inhomogeneous background flow environment. The theoretical aspects of the work are simplified by ...

  14. Effects of molecular transport on turbulence-chemistry interactions in a hydrogen-argon-air jet diffusion flame

    SciTech Connect (OSTI)

    Menon, S.; Calhoon, W.H. Jr.; Goldin, G. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Aerospace Engineering; Kerstein, A.R. [Sandia National Labs., Livermore, CA (United States)

    1994-01-01T23:59:59.000Z

    A numerical simulation of entrainment, turbulent advection, molecular import and chemical kinetics in a turbulent diffusion flame is used to investigate effects of molecular transport on turbulence-chemistry interactions. A fun finite-rate chemical mechanism is used to represent the combustion of a hydrogen-argon mixture issuing into air. Results based on incorporation of differential diffusion and variable Lewis number are compared to cases with the former effect, or both-effects, suppressed. Significant impact on radical species production and on NO emission index (based on a reduced mechanism for thermal NO) is found. A reduced mechanism for hydrogen-air combustion, omitting both effects and incorporating other simplifications, performs comparably except that its NO predictions agree well with the case of full chemistry and molecular transport, possibly due to cancellation of errors.

  15. A theory for radial jet reattachment flow

    E-Print Network [OSTI]

    Hadden, Lynne Loise

    2012-06-07T23:59:59.000Z

    , the velocity profile and mass entrainment are given accordrng to Goertler's t. wo- dimensional free jet theory. His analysrs of a free jet also assumes that. the turbulent eddy viscosity is constant ar ross the jet. (6) For the case of laminar flow... of total jet momentum. Laminar jet flow is approximated using Schlichting's velocity profile, whereas turbulent flow calculations are made assuming Goertler's velocity profile. Momentum integral principles are applied to the flow at reattachment...

  16. J_{E_T}: A Global Jet Finding Algorithm

    E-Print Network [OSTI]

    Yang Bai; Zhenyu Han; Ran Lu

    2014-11-13T23:59:59.000Z

    We introduce a new jet-finding algorithm for a hadron collider based on maximizing a J_{E_T} function for all possible combinations of particles in an event. This function prefers a larger value of the jet transverse energy and a smaller value of the jet mass. The jet shape is proved to be a circular cone in Cartesian coordinates with the geometric center shifted from the jet momentum toward the central region. The jet cone size shrinks for a more forward jet. We have implemented our J_{E_T} algorithm with a reasonable running time scaling as N n^3, where "N" is the total number of particles and "n" (much less than N) is the number of particles in a fiducial region. Many features of our J_{E_T} jets are similar to anti-k_t jets, including the reconstructed jet momentum and the "back-reaction" from soft contamination. Nevertheless, when the jet parameters in the two algorithms are matched using QCD jets, we find that the J_{E_T} algorithm has a larger efficiency than anti-k_t for identifying objects with hard splittings such as a W-jet.

  17. Flow, Turbulence and Combustion 62: 295333, 1999. 1999 Kluwer Academic Publishers. Printed in the Netherlands.

    E-Print Network [OSTI]

    in the Netherlands. 295 Application of PDF Modeling to Swirling and Nonswirling Turbulent Jets P.R. VAN SLOOTEN

  18. Modified shielding jet model for twin-jet shielding analysis

    E-Print Network [OSTI]

    Gilbride, Jennifer Frances

    2012-06-07T23:59:59.000Z

    the slowing of the jet flow due to turbulent mixing and entrainment of particles from the surrounding medium. The empirical formulations and velocity profiles derived for the respective regions of the jet consider this increase in entrained fluid... velocity profiles are integrated over their respective cross sections of the shielding jet to determine the total volumetric flowrate at the specified locations. A slug flow velocity approximation is then determined for each of the desired downstream...

  19. Clustering instability of the spatial distribution of inertial particles in turbulent flows Tov Elperin* and Nathan Kleeorin

    E-Print Network [OSTI]

    Elperin, Tov

    , cyclone dust separation, abrasive water-jet cutting and in turbulent com- bustion see, e.g., Refs. 1

  20. PASSIVE CONTROL OF PARTICLE DISPERSION IN A PARTICLE-LADEN CIRCULAR JET USING ELLIPTIC CO-ANNULAR FLOW: A MEANS FOR IMPROVING UTILIZATION AND EMISSION REDUCTIONS IN PULVERIZED COAL BURNER

    SciTech Connect (OSTI)

    Ahsan R. Choudhuri

    2003-06-01T23:59:59.000Z

    A passive control technology utilizing elliptic co-flow to control the particle flinging and particle dispersion in a particle (coal)-laden flow was investigated using experimental and numerical techniques. Preferential concentration of particles occurs in particle-laden jets used in pulverized coal burner and causes uncontrollable NO{sub x} formation due to inhomogeneous local stoichiometry. This particular project was aimed at characterizing the near-field flow behavior of elliptic coaxial jets. The knowledge gained from the project will serve as the basis of further investigation on fluid-particle interactions in an asymmetric coaxial jet flow-field and thus is important to improve the design of pulverized coal burners where non-homogeneity of particle concentration causes increased NO{sub x} formation.

  1. Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles

    E-Print Network [OSTI]

    Salpeter, Nathaniel O.

    2010-07-14T23:59:59.000Z

    The present work investigates the turbulent jet flow mixing of downward impinging jets within a staggered rod bundle based on previous experimental work. The two inlet jets had Reynold's numbers of 11,160 and 6,250 and were chosen to coincide...

  2. Characterization of mixing in a coaxial jet mixer for nanoparticle fabrication

    E-Print Network [OSTI]

    Gilson, Laura (Laura Marie)

    2013-01-01T23:59:59.000Z

    Mixing in a micro-scale coaxial turbulent jet mixer for the fabrication of nanoparticles for drug delivery was experimentally characterized. Rapid mixing due to turbulence offers improved control of nanoparticle production ...

  3. Multiple jet interactions

    E-Print Network [OSTI]

    Hehr, Roger James

    2012-06-07T23:59:59.000Z

    Type Designation Key Direction of Traverse: A - Axial R ? Radial A CON1 N (1) (3) (2) (2) Probe Type: N - Straight, a=O' S - Slant, a=45' (3) Configuration: CON1 CON2 CON3 CON4 CONS CON6 Jets h/D X/h 8 5. 0 16 2. 5 5. 33 7. 5 8 5. 0..., h/D=8. 0 and 2 Jets, h/D=8. 0. 0. 30 SYM INFORMATION: 8 RUN 24 RCON4N X/0 40 0. 25 oo 0. 20 0. 10 0. 05 0. 00 -0 4 -0 3 -0 2 -0. 1 0 0 0. 1 0 2 0 3 0 4 TyX Fig. 24 Distribution of Turbulence Intensity for 2 Jets, b/D=16. 0. 0. 30 BYN...

  4. Elliptic and circular wormholes

    E-Print Network [OSTI]

    P. F. González-Díaz

    1993-06-25T23:59:59.000Z

    Two new exact analytical solutions of the euclidean Einstein equations for a minimal massless scalar field and negative cosmological constant have been obtained. These solutions are given in terms of Jacobian elliptic or circular functions, rather than hyperbolic functions, connect large asymptotic regions of maximally-symmetric anti-DeSitter metrics through a microscopic throat, and correspond to negative definite components of the Ricci tensor. Therefore, they describe wormhole-like changes of topology driven by nucleation of baby universes. The quantum state of such elliptic and circular wormholes or handles is discussed in the most interesting inner and asymptotic regions.

  5. Astrophysical Jets

    SciTech Connect (OSTI)

    Madejski, Grzegorz (SLAC) [SLAC

    2006-05-01T23:59:59.000Z

    Many astrophysical sources - especially those powered by release of gravitational energy - are associated with an outflow of material, generally taking place along the axis of symmetry of the system. In the most extreme cases, the outflow is accelerated to relativistic speeds; such a phenomenon is known as an astrophysical jet. When a relativistic jet points close to our line of sight, the observed radiation is strongly Doppler-boosted. Most spectacular cases of astrophysical jets are those produced by active galactic nuclei, where the measured spectrum - presumably dominated by the radiation from the jet - reaches up to the multi-GeV range. Our knowledge of these jets is limited: we don't fully understand how are they formed, collimated, and accelerated, and what is the process of conversion of the bulk energy of the jet into radiation. We anticipate that the increased sensitivity of GLAST will provide us with spectacular data yielding new insights as to their origin and structure.

  6. Wave Packets and Turbulent Peter Jordan1

    E-Print Network [OSTI]

    Dabiri, John O.

    Wave Packets and Turbulent Jet Noise Peter Jordan1 and Tim Colonius2 1 D´epartement Fluides-control efforts is incomplete. Wave packets are intermittent, advecting disturbances that are correlated over review evidence of the existence, energetics, dynamics, and acous- tic efficiency of wave packets. We

  7. Stellar jets

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2008-05-23T23:59:59.000Z

    With a goal of understanding the conditions under which jets might be produced in novae and related objects, I consider the conditions under which jets are produced from other classes of accreting compact objects. I give an overview of accretion disk spectral states, including a discussion of in which states these jets are seen. I highlight the differences between neutron stars and black holes, which may help give us insights about when and how the presence of a solid surface may help or inhibit jet production.

  8. Turbulence and turbulent mixing in natural fluids

    E-Print Network [OSTI]

    Gibson, Carl H

    2010-01-01T23:59:59.000Z

    Turbulence and turbulent mixing in natural fluids begins with big bang turbulence powered by spinning combustible combinations of Planck particles and Planck antiparticles. Particle prograde accretion on a spinning pair releases 42% of the particle rest mass energy to produce more fuel for turbulent combustion. Negative viscosity and negative turbulence stresses work against gravity, creating mass-energy and space-time from the vacuum. Turbulence mixes cooling temperatures until a quark-gluon strong-force SF freeze-out. Gluon-viscosity anti-gravity ({\\Lambda}SF) exponentially inflates the fireball to preserve big bang turbulence information at scales larger than ct as the first fossil turbulence. Cosmic microwave background CMB temperature anisotropies show big bang turbulence fossils along with fossils of weak plasma turbulence triggered (10^12 s) as plasma viscous forces permit gravitational fragmentation on supercluster to galaxy mass scales (10^13 s). Turbulent morphologies and viscous-turbulent lengths a...

  9. Turbulent combustion

    SciTech Connect (OSTI)

    Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01T23:59:59.000Z

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  10. Formation of Liquid Methane-Water Mixture during Combustion of a Laminar Methane Jet at Supercritical Pressures

    E-Print Network [OSTI]

    Gülder, �mer L.

    Formation of Liquid Methane-Water Mixture during Combustion of a Laminar Methane Jet in laminar jet flames of methane at elevated pressures in a high-pressure combustion chamber, we have MPa, after the laminar methane jet flame had been stabilized on a co-flow circular nozzle-type burner

  11. Emerging Jets

    E-Print Network [OSTI]

    Pedro Schwaller; Daniel Stolarski; Andreas Weiler

    2015-02-24T23:59:59.000Z

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  12. Emerging Jets

    E-Print Network [OSTI]

    Schwaller, Pedro; Weiler, Andreas

    2015-01-01T23:59:59.000Z

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilit...

  13. Turbulence-chemistry interactions in reacting flows

    SciTech Connect (OSTI)

    Barlow, R.S.; Carter, C.D. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01T23:59:59.000Z

    Interactions between turbulence and chemistry in nonpremixed flames are investigated through multiscalar measurements. Simultaneous point measurements of major species, NO, OH, temperature, and mixture fraction are obtained by combining spontaneous Raman scattering, Rayleigh scattering, and laser-induced fluorescence (LIF). NO and OH fluorescence signals are converted to quantitative concentrations by applying shot-to-shot corrections for local variations of the Boltzmann fraction and collisional quenching rate. These measurements of instantaneous thermochemical states in turbulent flames provide insights into the fundamental nature of turbulence-chemistry interactions. The measurements also constitute a unique data base for evaluation and refinement of turbulent combustion models. Experimental work during the past year has focused on three areas: (1) investigation of the effects of differential molecular diffusion in turbulent combustion: (2) experiments on the effects of Halon CF{sub 3}Br, a fire retardant, on the structure of turbulent flames of CH{sub 4} and CO/H{sub 2}/N{sub 2}; and (3) experiments on NO formation in turbulent hydrogen jet flames.

  14. Why Do Disks Form Jets?

    E-Print Network [OSTI]

    D Lynden-Bell

    2002-03-27T23:59:59.000Z

    It is argued that jet modelers have given insufficient study to the natural magneto-static configurations of field wound up in the presence of a confining general pressure. Such fields form towers whose height grows with each twist at a velocity comparable to the circular velocity of the accretion disk that turns them. A discussion of the generation of such towers is preceded by a brief history of the idea that quasars, active galaxies, and galactic nuclei contain giant black holes with accretion disks.

  15. Circular chemiresistors for microchemical sensors

    DOE Patents [OSTI]

    Ho, Clifford K. (Albuquerque, NM)

    2007-03-13T23:59:59.000Z

    A circular chemiresistor for use in microchemical sensors. A pair of electrodes is fabricated on an electrically insulating substrate. The pattern of electrodes is arranged in a circle-filling geometry, such as a concentric, dual-track spiral design, or a circular interdigitated design. A drop of a chemically sensitive polymer (i.e., chemiresistive ink) is deposited on the insulating substrate on the electrodes, which spreads out into a thin, circular disk contacting the pair of electrodes. This circularly-shaped electrode geometry maximizes the contact area between the pair of electrodes and the polymer deposit, which provides a lower and more stable baseline resistance than with linear-trace designs. The circularly-shaped electrode pattern also serves to minimize batch-to-batch variations in the baseline resistance due to non-uniform distributions of conductive particles in the chemiresistive polymer film.

  16. Terascale direct numerical simulations of turbulent combustion using S3D This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Kuzmanovic, Aleksandar

    -neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between

  17. TURBULENT FRBRNNING MVK130 Turbulent Combustion

    E-Print Network [OSTI]

    TURBULENT F�RBR�NNING MVK130 Turbulent Combustion Poäng: 3.0 Betygskala: TH Valfri för: M4 to combustion, McGraw-Hill 1996. #12;

  18. Nuclear spin circular dichroism

    SciTech Connect (OSTI)

    Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland)] [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Rizzo, Antonio [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy)] [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy); Kauczor, Joanna; Norman, Patrick [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden)] [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)] [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)

    2014-04-07T23:59:59.000Z

    Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

  19. New perspectives on superparameterization for geophysical turbulence

    SciTech Connect (OSTI)

    Majda, Andrew J. [Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States); Center for Prototype Climate Modelling, NYU Abu Dhabi, Abu Dhabi (United Arab Emirates); Grooms, Ian, E-mail: grooms@cims.nyu.edu [Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States)

    2014-08-15T23:59:59.000Z

    This is a research expository paper regarding superparameterization, a class of multi-scale numerical methods designed to cope with the intermittent multi-scale effects of inhomogeneous geophysical turbulence where energy often inverse-cascades from the unresolved scales to the large scales through the effects of waves, jets, vortices, and latent heat release from moist processes. Original as well as sparse space–time superparameterization algorithms are discussed for the important case of moist atmospheric convection including the role of multi-scale asymptotic methods in providing self-consistent constraints on superparameterization algorithms and related deterministic and stochastic multi-cloud parameterizations. Test models for the statistical numerical analysis of superparameterization algorithms are discussed both to elucidate the performance of the basic algorithms and to test their potential role in efficient multi-scale data assimilation. The very recent development of grid-free seamless stochastic superparameterization methods for geophysical turbulence appropriate for “eddy-permitting” mesoscale ocean turbulence is presented here including a general formulation and illustrative applications to two-layer quasigeostrophic turbulence, and another difficult test case involving one-dimensional models of dispersive wave turbulence. This last test case has randomly generated solitons as coherent structures which collapse and radiate wave energy back to the larger scales, resulting in strong direct and inverse turbulent energy cascades.

  20. Direct numerical simulation of turbulent reacting flows

    SciTech Connect (OSTI)

    Chen, J.H. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01T23:59:59.000Z

    The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.

  1. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, Antoni K. (Kensington, CA); Maxson, James A. (Berkeley, CA); Hensinger, David M. (Albany, CA)

    1993-01-01T23:59:59.000Z

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

  2. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, A.K.; Maxson, J.A.; Hensinger, D.M.

    1993-12-21T23:59:59.000Z

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure. 24 figures.

  3. Effect of Nozzle Geometry on Jet Noise Reduction Using Fan Flow Deflectors

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    or sideforce p = pressure q = dynamic pressure S = wedge wetted area u = mean velocity in jet plume U = nozzleEffect of Nozzle Geometry on Jet Noise Reduction Using Fan Flow Deflectors Dimitri Papamoschou of baseline nozzle shape on the ability of fan flow deflectors to reduce downward-emitted turbulent mixing

  4. Center for Turbulence Research Annual Research Briefs 2012

    E-Print Network [OSTI]

    Wang, Wei

    a model for uncertainty quantification (UQ) of high-speed turbulent combustion in a scramjet engine/boundary layer interaction, a phenomenon important to scramjet combustors. In addition to aleatory uncertainties from simulation of a full scramjet engine to an investigation of crackling supersonic jets to solar

  5. Center for Turbulence Research Proceedings of the Summer Program 2012

    E-Print Network [OSTI]

    Wang, Wei

    , such as shear-layers, piloted, bluff-body and swirl-stabilized jet diffu- sion flames and gas-turbine combustorsCenter for Turbulence Research Proceedings of the Summer Program 2012 397 Budget analysis and model. Kolla AND J. H. Chen An a priori analysis of the flamelet-model is conducted to systematically assess

  6. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

    Schefer, R.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01T23:59:59.000Z

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  7. Timewise morphology of turbulent diffusion flame by means of image processing

    SciTech Connect (OSTI)

    Torii, Shuichi; Yano, Toshiaki; Tsuchino, Fumihiro

    1999-07-01T23:59:59.000Z

    An experimental study is performed to investigate the dynamic behavior of jet diffusion flames from a vertical circular nozzle. A real-time image processing on slow-motion video recording using the high-speed video camera is employed to clarify the flame morphology. Emphasis is placed on the timewise variation of the flame length, H, the peripheral distance of the flame, L, and the projected area of the flame contour, S, based on the RGB values of the flame. Here, RGB implies the three primary colors, i.e., red, green and blue, respectively. Propane is used as fuel and a burner tube of 2.40 mm inside diameter is employed here. It is found from the study that (1) a real-time color image processing with the aid of a slow-motion video recording discriminates the flame shape and discloses the flame behavior with time, (2) H, L and S vary periodically with time, and (3) the time-averaged value of L{sup 2}/S and its turbulence intensity, which is defined here, are intensified with an increase in the Reynolds number.

  8. Turbulent Nonpremixed Flames (TNF): Experimental Data Archives and Computational Submodels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    In the 1990s an international collaboration formed around a series of workshops that became known collectively as the International Workshop on Measurement and Computation of Turbulent Non-Premixed Flames (TNF). An online library, hosted by Sandia National Laboratory (California) was established that provides data sets and submodels or "mechanisms" for the study of turbulence-chemistry interactions in turbulent nonpremixed and partially premixed combustion. Data are organized by flame types: simple jet flames, piloted jet flames, bluff body flames, and swirl flames. These data sets provide a means for collaborative comparisons of both measured and simulated/modeled research results and also assist scientists in determining priorities for further research. More than 20 data sets or databases are available from this website, along with various downloadable files of chemical mechanisms. The website also provides an extensive bibliography and the proceedings of the workshops themselves from 1996 through 2012. Information continues to be added to this collection.

  9. Jet Structure in Heavy Ion Collisions

    E-Print Network [OSTI]

    Blaizot, Jean-Paul

    2015-01-01T23:59:59.000Z

    We review recent theoretical developments in the study of the structure of jets that are produced in ultra relativistic heavy ion collisions. The core of the review focusses on the dynamics of the parton cascade that is induced by the interactions of a fast parton crossing a quark-gluon plasma. We recall the basic mechanisms responsible for medium induced radiation, underline the rapid disappearance of coherence effects, and the ensuing probabilistic nature of the medium induced cascade. We discuss how large radiative corrections modify the classical picture of the gluon cascade, and how these can be absorbed in a renormalization of the jet quenching parameter $\\hat q $. Then, we analyze the (wave)-turbulent transport of energy along the medium induced cascade, and point out the main characteristics of the angular structure of such a cascade. Finally, color decoherence of the in-cone jet structure is discussed. Modest contact with phenomenology is presented towards the end of the review.

  10. The effects of an ambient salinity gradient on the dilution of dense brine jets

    E-Print Network [OSTI]

    McCullough, Gary Wayne

    2012-06-07T23:59:59.000Z

    s helpful to briefly discuss the theory of turbulent jets. An overview of the theory of turbulent jets and plumes is presented by Fischer, et al (4). This over view, along w1th the analys1s presented by Chu (2) and Chu and Goldberg (3), is used.... In order to continue, some assumptions of the entrainment process must be considered. Chu and Goldberg (3) assumed that the increase in the radius of the jet could be described by: dr W (16) dx U where W is a local velocity scale, a is the entrainment...

  11. Inclusive Jets in PHP

    E-Print Network [OSTI]

    Roloff, Philipp

    2013-01-01T23:59:59.000Z

    Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, anti-k_T or SIScone jet algorithms. Cross sections are presented as functions of the jet pseudorapidity, eta(jet), and the jet transverse energy, E_T(jet). Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E_T(jet) and high eta(jet). The cross sections have the potential to improve the determination of the PDFs in future QCD fits. Values of alpha_s(M_Z) have been extracted from the measurements based on different jet algorithms. In addition, the energy-scale dependence of the strong coupling was determined.

  12. Inclusive Jets in PHP

    E-Print Network [OSTI]

    Philipp Roloff

    2013-10-23T23:59:59.000Z

    Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, anti-k_T or SIScone jet algorithms. Cross sections are presented as functions of the jet pseudorapidity, eta(jet), and the jet transverse energy, E_T(jet). Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E_T(jet) and high eta(jet). The cross sections have the potential to improve the determination of the PDFs in future QCD fits. Values of alpha_s(M_Z) have been extracted from the measurements based on different jet algorithms. In addition, the energy-scale dependence of the strong coupling was determined.

  13. Turbulent flow in graphene

    E-Print Network [OSTI]

    Kumar S. Gupta; Siddhartha Sen

    2010-06-05T23:59:59.000Z

    We demonstrate the possibility of a turbulent flow of electrons in graphene in the hydrodynamic region, by calculating the corresponding turbulent probability density function. This is used to calculate the contribution of the turbulent flow to the conductivity within a quantum Boltzmann approach. The dependence of the conductivity on the system parameters arising from the turbulent flow is very different from that due to scattering.

  14. TURBULENT FRBRNNING MVK 130 Turbulent Combustion

    E-Print Network [OSTI]

    TURBULENT F�RBR�NNING MVK 130 Turbulent Combustion Antal poäng: 3.0. Valfri för: M4. Kursansvarig program med hänsyn till de modeller som används. Litteratur S.R. Turns: An introduction to combustion, Mc

  15. Quantum Gravity and Turbulence

    E-Print Network [OSTI]

    Vishnu Jejjala; Djordje Minic; Y. Jack Ng; Chia-Hsiung Tze

    2010-05-18T23:59:59.000Z

    We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.

  16. Modeling Compressed Turbulence

    SciTech Connect (OSTI)

    Israel, Daniel M. [Los Alamos National Laboratory

    2012-07-13T23:59:59.000Z

    From ICE to ICF, the effect of mean compression or expansion is important for predicting the state of the turbulence. When developing combustion models, we would like to know the mix state of the reacting species. This involves density and concentration fluctuations. To date, research has focused on the effect of compression on the turbulent kinetic energy. The current work provides constraints to help development and calibration for models of species mixing effects in compressed turbulence. The Cambon, et al., re-scaling has been extended to buoyancy driven turbulence, including the fluctuating density, concentration, and temperature equations. The new scalings give us helpful constraints for developing and validating RANS turbulence models.

  17. Stochastic superparameterization in quasigeostrophic turbulence

    SciTech Connect (OSTI)

    Grooms, Ian, E-mail: grooms@cims.nyu.edu [Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States); Majda, Andrew J., E-mail: jonjon@cims.nyu.edu [Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States); Center for Prototype Climate Modelling, NYU-Abu Dhabi (United Arab Emirates)

    2014-08-15T23:59:59.000Z

    In this article we expand and develop the authors' recent proposed methodology for efficient stochastic superparameterization algorithms for geophysical turbulence. Geophysical turbulence is characterized by significant intermittent cascades of energy from the unresolved to the resolved scales resulting in complex patterns of waves, jets, and vortices. Conventional superparameterization simulates large scale dynamics on a coarse grid in a physical domain, and couples these dynamics to high-resolution simulations on periodic domains embedded in the coarse grid. Stochastic superparameterization replaces the nonlinear, deterministic eddy equations on periodic embedded domains by quasilinear stochastic approximations on formally infinite embedded domains. The result is a seamless algorithm which never uses a small scale grid and is far cheaper than conventional SP, but with significant success in difficult test problems. Various design choices in the algorithm are investigated in detail here, including decoupling the timescale of evolution on the embedded domains from the length of the time step used on the coarse grid, and sensitivity to certain assumed properties of the eddies (e.g. the shape of the assumed eddy energy spectrum). We present four closures based on stochastic superparameterization which elucidate the properties of the underlying framework: a ‘null hypothesis’ stochastic closure that uncouples the eddies from the mean, a stochastic closure with nonlinearly coupled eddies and mean, a nonlinear deterministic closure, and a stochastic closure based on energy conservation. The different algorithms are compared and contrasted on a stringent test suite for quasigeostrophic turbulence involving two-layer dynamics on a ?-plane forced by an imposed background shear. The success of the algorithms developed here suggests that they may be fruitfully applied to more realistic situations. They are expected to be particularly useful in providing accurate and efficient stochastic parameterizations for use in ensemble-based state estimation and prediction.

  18. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations

    SciTech Connect (OSTI)

    Rutland, Christopher J.

    2009-04-26T23:59:59.000Z

    The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets.

  19. Jets at all scales

    E-Print Network [OSTI]

    F. Tavecchio

    2002-12-11T23:59:59.000Z

    I discuss recent developments in the field of relativistic jets in AGNs. After a brief review of our current knowledge of emission from Blazars, I discuss some consequences of the recent detection made by {\\it Chandra} of X-ray emission from extended jets. Finally I report some recent results on the problem of the connection between accretion and jets, study that in principle could shed light on the important issue of jet formation.

  20. An experimental investigation on turbulent flow through symmetric wall subchannels of two rod bundles

    SciTech Connect (OSTI)

    Wu, S.R. (Inst. of Nuclear Energy Technology, Tsinghua Univ., P.O. Box 1021, Beijing (CN)); Rehme, K. (Kernforschungszentrum Karlsruhe GmbH (Germany, F.R.). Inst. fuer Neutronenphysik und Reaktortechnik)

    1990-01-01T23:59:59.000Z

    Measurements of the mean velocity, wall shear stresses, and turbulent Reynolds stresses have been performed in wall subchannels of two rod bundles. The rod bundle of four parallel rods was arranged symmetrically in a rectangular channel. The pitch-to-diameter ratio was 1.148, and the wall-to-diameter ratios were 1.045 and 1.074, respectively. The Reynolds numbers in these investigations were 6.11 {times} 10{sup 4} and 7.07 {times} 10{sup 4}, respectively. The experimental results demonstrate that the structure of turbulence in rod bundles differs greatly from the structure in circular tubes. Especially in the narrow gaps between the rods and channel walls, there are increased levels of turbulence intensities in both the axial and azimuthal directions and, hence, of the kinetic energy of turbulence, caused by a strong turbulent momentum transport through the gaps.

  1. Circular permutant GFP insertion folding reporters

    SciTech Connect (OSTI)

    Waldo, Geoffrey S; Cabantous, Stephanie

    2013-02-12T23:59:59.000Z

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  2. Circular permutant GFP insertion folding reporters

    SciTech Connect (OSTI)

    Waldo, Geoffrey S. (Santa Fe, NM); Cabantous, Stephanie (Los Alamos, NM)

    2008-06-24T23:59:59.000Z

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  3. Circular permutant GFP insertion folding reporters

    SciTech Connect (OSTI)

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2013-04-16T23:59:59.000Z

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  4. Circular permutant GFP insertion folding reporters

    SciTech Connect (OSTI)

    Waldo, Geoffrey S. (Santa Fe, NM); Cabantous, Stephanie (Los Alamos, NM)

    2011-06-14T23:59:59.000Z

    Provided are methods of assaying and improving protein folding using circular permutants of fluorescent proteins, including circular permutants of GFP variants and combinations thereof. The invention further provides various nucleic acid molecules and vectors incorporating such nucleic acid molecules, comprising polynucleotides encoding fluorescent protein circular permutants derived from superfolder GFP, which polynucleotides include an internal cloning site into which a heterologous polynucleotide may be inserted in-frame with the circular permutant coding sequence, and which when expressed are capable of reporting on the degree to which a polypeptide encoded by such an inserted heterologous polynucleotide is correctly folded by correlation with the degree of fluorescence exhibited.

  5. Microquasars and Jets

    E-Print Network [OSTI]

    Sylvain Chaty

    2005-06-01T23:59:59.000Z

    I present an overview of past, present and future research on microquasars and jets, showing that microquasars, i.e. galactic jet sources, are among the best laboratories for high energy phenomena. After remindind the analogy with quasars, I focus on one of the best microquasar representatives, probably the archetype, namely GRS 1915+105, and present accretion and ejection phenomena, showing that only a multi-wavelength approach allows a better understanding of phenomena occuring in these sources. Thereafter, I review jets at different scales: compact jets, large-scale jets, and the interactions between ejections and the surrounding medium. I finish by speaking about microblazars and ultraluminous X-ray sources.

  6. Decay of swirl in turbulent two phase flow

    E-Print Network [OSTI]

    Neeley, Patrick Foster

    2012-06-07T23:59:59.000Z

    decrease in Reynolds number. Also, it was found that within experimental accuracy the decay was independent of initial swirl intensity. Their theoretical analysis of swirl decay characteristics in turbulent flow and the experiments conducted were... concentrations of the Polyox were put into the water in a uniform procedure in order to obtain consist. ent results. A venturi mixer was designed and used to di perse the polymer particles into the water in the mixing tank. The vigorous stir- ring bv the jet...

  7. Jet Simulation in a Diesel Engine James Glimm zx , M.N. Kim x , X.-L. Li z , R. Samulyak x , and Z.-L. Xu yz

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    Jet Simulation in a Diesel Engine James Glimm zx , M.N. Kim x , X.-L. Li z , R. Samulyak x , and Z and spray formation in a diesel engine by the Front Tracking method. We model mixed vapor-liquid region of a high speed diesel jet injected through a circular nozzle are the key to design a fuel e

  8. Ris-R-1188(EN) Turbulence and turbulence-

    E-Print Network [OSTI]

    Risø-R-1188(EN) Turbulence and turbulence- generated structural loading in wind turbine clusters to ensure sufficient structural sustainability of the wind turbines exposed to "wind farm flow turbulence intensity inside the wind farm and direct-wake turbulence intensity are being devised and a method

  9. Four Lectures on Turbulent Combustion

    E-Print Network [OSTI]

    Peters, Norbert

    Four Lectures on Turbulent Combustion N. Peters Institut f¨ur Technische Mechanik RWTH Aachen Turbulent Combustion: Introduction and Overview 1 1.1 Moment Methods in Modeling Turbulence with Combustion and Velocity Scales . . . . . . . . . . . 11 1.4 Regimes in Premixed Turbulent Combustion

  10. Simple Models for Turbulent Self-Regulation in Galaxy Disks

    E-Print Network [OSTI]

    Curtis Struck; Daniel C. Smith

    1999-07-29T23:59:59.000Z

    We propose that turbulent heating, wave pressure and gas exchanges between different regions of disks play a dominant role in determining the preferred, quasi-equilibrium, self-similar states of gas disks on large-scales. We present simple families of analytic, thermohydrodynamic models for these global states, which include terms for turbulent pressure and Reynolds stresses. Star formation rates, phase balances, and hydrodynamic forces are all tightly coupled and balanced. The models have stratified radial flows, with the cold gas slowly flowing inward in the midplane of the disk, and with the warm/hot phases that surround the midplane flowing outward. The models suggest a number of results that are in accord with observation, as well as some novel predictions, including the following. 1) The large-scale gas density and thermal phase distributions in galaxy disks can be explained as the result of turbulent heating and spatial couplings. 2) The turbulent pressures and stresses that drive radial outflows in the warm gas also allow a reduced circular velocity there. This effect was observed by Swaters, Sancisi and van der Hulst in NGC 891, a particularly turbulent edge-on disk. The models predict that the effect should be universal in such disks. 3) They suggest that a star formation rate like the phenomenological Schmidt Law is the natural result of global thermohydrodynamical balance, and may not obtain in disks far from equilibrium. (Abridged)

  11. Hotspots, Jets and Environments

    E-Print Network [OSTI]

    M. J. Hardcastle

    2007-07-12T23:59:59.000Z

    I discuss the nature of `hotspots' and `jet knots' in the kpc-scale structures of powerful radio galaxies and their relationship to jet-environment interactions. I describe evidence for interaction between the jets of FRI sources and their local environments, and discuss its relationship to particle acceleration, but the main focus of the paper is the hotspots of FRIIs and on new observational evidence on the nature of the particle acceleration associated with them.

  12. Information Content of Turbulence

    E-Print Network [OSTI]

    Rory Cerbus; Walter Goldburg

    2013-07-03T23:59:59.000Z

    We treat a turbulent velocity field as a message in the same way as a book or a picture. All messages can be described by their entropy per symbol $h$, defined as in Shannon's theory of communication. In a turbulent flow, as the Reynolds number $Re$ increases, more correlated degrees of freedom are excited and participate in the turbulent cascade. Experiments in a turbulent soap film suggest that the spatial entropy density $h$ is a decreasing function of $Re$, namely $h \\propto -\\log Re$ + const. In the logistic map, also analyzed here, increasing the control parameter $r$ increases $h$. A modified logistic map with additional coupling to past iterations suggests the significance of correlations.

  13. Response Relationship Between Juvenile Salmon and an Autonomous Sensor in Turbulent Flows

    SciTech Connect (OSTI)

    Richmond, Marshall C.; Deng, Zhiqun; McKinstry, Craig A.; Mueller, Robert P.; Carlson, Thomas J.; Dauble, Dennis D.

    2009-04-01T23:59:59.000Z

    Juvenile fall chinook salmon (Oncorhynchus tshawythscha) and an autonomous sensor device (Sensor Fish) were exposed to turbulent shear flows in order to determine how hydraulic conditions effected fish injury response. Studies were designed to establish correlation metrics between Sensor Fish device measurements and live fish injuries by conducting concurrent releases in a range of turbulent shear flows. Comparisons were made for two exposure scenarios. In the fast-fish-to-slow-water scenario, test fish were carried by the fast-moving water of a submerged turbulent jet and exposed into the standing water of a flume. In the slow-fish-to-fast-water scenario, test fish were introduced into a turbulent jet from standing water through an introduction tube placed just outside the edge of the jet. Motion-tracking analysis was performed on high-speed, high-resolution digital videos of all the releases at water jet velocities ranging from 3 to 22.9 m · s?1. Velocities of the Sensor Fish were very similar to those of live fish, but maximum accelerations of live fish were larger than those by Sensor Fish for all the nozzle velocities of both cenarios. A 10% probability of major injury threshold was found to occur at sensor fish accelerations of 513 and 260 (m · s?2) for the fast-fish-to-slow-water and slow-fish-to-fast-water scenarios, respectively. The findings provide a linkage between laboratory experiments of fish injury, field survival studies, and numerical modeling.

  14. A Scalable Turbulent Mixing Aerosol Reactor for Oxide-Coated Silicon Nanoparticles

    E-Print Network [OSTI]

    Atwater, Harry

    energy supplied to the reactor by high velocity gas jets. The apparatus described here increased the throughput by a factor of 100 above previous laminar flow reactors, and the induced fast mixing enables scaleA Scalable Turbulent Mixing Aerosol Reactor for Oxide-Coated Silicon Nanoparticles Dean M. Holunga

  15. Numerical Study of Steady Turbulent Flow through Bifurcated Nozzles in Continuous Casting

    E-Print Network [OSTI]

    Thomas, Brian G.

    . The effects of nozzle design and casting process operating variables on the jet characteristics exitingNumerical Study of Steady Turbulent Flow through Bifurcated Nozzles in Continuous Casting FADY M. NAJJAR, BRIAN G. THOMAS, and DONALD E. HERSHEY Bifurcated nozzles are used in continuous casting

  16. Interface and process for enhanced transmission of non-circular ion beams between stages at unequal pressure

    DOE Patents [OSTI]

    Tang, Keqi (Richland, WA); Shvartsburg, Alexandre A. (Richland, WA); Smith, Richard D. (Richland, WA)

    2008-03-04T23:59:59.000Z

    The invention discloses a new interface with non-circular conductance limit aperture(s) useful for effective transmission of non-circular ion beams between stages with different gas pressure. In particular, the invention provides an improved coupling of field asymmetric waveform ion mobility spectrometry (FAIMS) analyzers of planar or side-to-side geometry to downstream stages such as mass spectrometry or ion mobility spectrometry. In this case, the non-circular aperture is rectangular; other geometries may be optimum in other applications. In the preferred embodiment, the non-circular aperture interface is followed by an electrodynamic ion funnel that may focus wide ion beams of any shape into tight circular beams with virtually no losses. The jet disrupter element of the funnel may also have a non-circular geometry, matching the shape of arriving ion beam. The improved sensitivity of planar FAIMS/MS has been demonstrated in experiments using a non-contiguous elongated aperture but other embodiments (e.g., with a contiguous slit aperture) may be preferable, especially in conjunction with an ion funnel operated at high pressures.

  17. The turbulent structure of the jet in cross-flow

    E-Print Network [OSTI]

    Lanitis, Nicolas

    2014-04-08T23:59:59.000Z

    downstream. Other applications of the JICF include the area of aerodynamics with Vertical and/or Short TakeOff/Landing (V/STOL) aircrafts and thrust vector control (control of missiles and rockets). Research in this area was related with the cross sectional...

  18. A spray-suppression model for turbulent combustion

    SciTech Connect (OSTI)

    DESJARDIN,PAUL E.; TIESZEN,SHELDON R.; GRITZO,LOUIS A.

    2000-02-14T23:59:59.000Z

    A spray-suppression model that captures the effects of liquid suppressant on a turbulent combusting flow is developed and applied to a turbulent diffusion flame with water spray suppression. The spray submodel is based on a stochastic separated flow approach that accounts for the transport and evaporation of liquid droplets. Flame extinguishment is accounted for by using a perfectly stirred reactor (PSR) submodel of turbulent combustion. PSR pre-calculations of flame extinction times are determined using CHEMKIN and are compared to local turbulent time scales of the flow to determine if local flame extinguishment has occurred. The PSR flame extinguishment and spray submodels are incorporated into Sandia's flow fire simulation code, VULCAN, and cases are run for the water spray suppression studies of McCaffrey for turbulent hydrogen-air jet diffusion flames. Predictions of flame temperature decrease and suppression efficiency are compared to experimental data as a function of water mass loading using three assumed values of drop sizes. The results show that the suppression efficiency is highly dependent on the initial droplet size for a given mass loading. A predicted optimal suppression efficiency was observed for the smallest class of droplets while the larger drops show increasing suppression efficiency with increasing mass loading for the range of mass loadings considered. Qualitative agreement to the experiment of suppression efficiency is encouraging, however quantitative agreement is limited due to the uncertainties in the boundary conditions of the experimental data for the water spray.

  19. Vibrations of circular steel plates with damping

    E-Print Network [OSTI]

    Sheth, Prafulchandra Naginlal

    1967-01-01T23:59:59.000Z

    distributed. Usually, the prime objection to vibrations produced by machines is their effect on humans. These are high frequency vibrations that produce troublesome noise. Low frequency vibrations are often trans- mitted and these may damage nearby... materials used with fans, motors, engines, presses, turbines and similar machines. Byars (1)* studied vibrations of a circular plate on three supports for node patterns, amplitudes and frequencies. Ballentine (2) investigated the vibrations of circular...

  20. Optimization of a high-efficiency jet ejector by computational fluid dynamic software

    E-Print Network [OSTI]

    Watanawanavet, Somsak

    2005-08-29T23:59:59.000Z

    Computational Fluid Dynamics (CFD) software. A conventional finite-volume scheme was utilized to solve two-dimensional transport equations with the standard k-?? turbulence model (Kim et. al., 1999). In this study of a constant-area jet ejector, all parameters...

  1. Turbulence Structure and Wall Signature in Hypersonic Turbulent Boundary Layer

    E-Print Network [OSTI]

    Martín, Pino

    Turbulence Structure and Wall Signature in Hypersonic Turbulent Boundary Layer Yin-Chiu Kan , Clara and hypersonic turbulent boundary layer datasets from direct numerical simulation (DNS). Contour plots and Marusic5 and Mathis, Hutchins and Marusic16 ). In contrast to supersonic and hypersonic flow regimes

  2. Solar wind versus magnetosheath turbulence.

    E-Print Network [OSTI]

    Demoulin, Pascal

    order statistics (Number of data points ~ 105) 22 4 !" !" = # # # $ $ b b F ! ! " ! # )()( tbtb bSolar wind versus magnetosheath turbulence. Observations of Alfven vortices. O. Alexandrova A properties of turbulence (hydrodynamics) is independent on the energy injection & dissipation energy

  3. Interactions of a Light Hypersonic Jet with a Non-Uniform Interstellar Medium

    E-Print Network [OSTI]

    R. S. Sutherland; G. V. Bicknell

    2007-07-25T23:59:59.000Z

    We present three dimensional simulations of the interaction of a light hypersonic jet with an inhomogeneous thermal and turbulently supported disk in an elliptical galaxy. We model the jet as a light, supersonic non-relativistic flow with parameters selected to be consistent with a relativistic jet with kinetic power just above the FR1/FR2 break. We identify four generic phases in the evolution of such a jet with the inhomogeneous interstellar medium: 1) an initial ``flood and channel'' phase, where progress is characterized by high pressure gas finding changing weak points in the ISM, flowing through channels that form and re-form over time, 2) a spherical, energy-driven bubble phase, were the bubble is larger than the disk scale, but the jet remains fully disrupted close to the nucleus, 3) a rapid, jet break--out phase the where jet breaks free of the last dense clouds, becomes collimated and pierces the spherical bubble, and 4) a classical phase, the jet propagates in a momentum-dominated fashion leading to the classical jet + cocoon + bow-shock structure. Mass transport in the simulations is investigated, and we propose a model for the morphology and component proper motions in the well-studied Compact Symmetric Object 4C31.04.

  4. Reliability of astrophysical jet simulations in 2D: On inter-code reliability and numerical convergence

    E-Print Network [OSTI]

    M. Krause; M. Camenzind

    2001-10-22T23:59:59.000Z

    In the present paper, we examine the convergence behavior and inter-code reliability of astrophysical jet simulations in axial symmetry. We consider both, pure hydrodynamic jets and jets with a dynamically significant magnetic field. The setups were chosen to match the setups of two other publications, and recomputed with the MHD code NIRVANA. We show that NIRVANA and the two other codes give comparable, but not identical results. We find that some global properties of a hydrodynamical jet simulation, like e.g. the bow shock velocity, converge at 100 points per beam radius (ppb) with NIRVANA. The situation is quite different after switching on the toroidal magnetic field: In this case, global properties converge even at 10 ppb. In both cases, details of the inner jet structure and especially the terminal shock region are still insufficiently resolved, even at our highest resolution of 70 ppb in the magnetized case and 400 ppb for the pure hydrodynamic jet. In the case of our highest resolution simulation, we can report two new features: First, small scale Kelvin-Helmholtz instabilities are excited at the contact discontinuity next to the jet head. This slows down the development of the long wavelength Kelvin-Helmholtz instability and its turbulent cascade to smaller wavelengths. Second, the jet head develops Rayleigh-Taylor instabilities which manage to entrain an increasing amount of mass from the ambient medium with resolution. This region extends in our highest resolution simulation over 2 jet radii in the axial direction.

  5. Strong Imbalanced Turbulence

    E-Print Network [OSTI]

    A. Beresnyak; A. Lazarian

    2008-07-07T23:59:59.000Z

    We consider stationary, forced, imbalanced, or cross-helical MHD Alfvenic turbulence where the waves traveling in one direction have higher amplitudes than the opposite waves. This paper is dedicated to so-called strong turbulence, which cannot be treated perturbatively. Our main result is that the anisotropy of the weak waves is stronger than the anisotropy of a strong waves. We propose that critical balance, which was originally conceived as a causality argument, has to be amended by what we call a propagation argument. This revised formulation of critical balance is able to handle the imbalanced case and reduces to old formulation in the balanced case. We also provide phenomenological model of energy cascading and discuss possibility of self-similar solutions in a realistic setup of driven turbulence.

  6. ON THE ORIGIN OF INTERGRANULAR JETS

    SciTech Connect (OSTI)

    Yurchyshyn, V. B.; Goode, P. R.; Abramenko, V. I. [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States); Steiner, O. [Kiepenheuer-Institut fuer Sonnenphysik, Schoeneckstrasse 6, D-79104 Freiburg (Germany)

    2011-08-01T23:59:59.000Z

    We observe that intergranular jets, originating in the intergranular space surrounding individual granules, tend to be associated with granular fragmentation, in particular, with the formation and evolution of a bright granular lane (BGL) within individual granules. The BGLs have recently been identified as vortex tubes by Steiner et al. We further discover the development of a well-defined bright grain located between the BGL and the dark intergranular lane to which it is connected. Signatures of a BGL may reach the lower chromosphere and can be detected in off-band H{alpha} images. Simulations also indicate that vortex tubes are frequently associated with small-scale magnetic fields. We speculate that the intergranular jets detected in the New Solar Telescope (NST) data may result from the interaction between the turbulent small-scale fields associated with the vortex tube and the larger-scale fields existing in the intergranular lanes. The intergranular jets are much smaller and weaker than all previously known jet-like events. At the same time, they appear much more numerous than the larger events, leading us to the speculation that the total energy release and mass transport by these tiny events may not be negligible in the energy and mass-flux balance near the temperature minimum atop the photosphere. The study is based on the photospheric TiO broadband (1.0 nm) filter data acquired with the 1.6 m NST operating at the Big Bear Solar Observatory. The data set also includes NST off-band H{alpha} images collected through a Zeiss Lyot filter with a passband of 0.025 nm.

  7. EPISODIC JETS AS THE CENTRAL ENGINE OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Yuan Feng [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang Bing, E-mail: fyuan@shao.ac.cn, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)

    2012-09-20T23:59:59.000Z

    Most gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball model, which suggests a magnetic origin of GRBs. Given that powerful episodic jets have been observed along with continuous jets in other astrophysical black hole systems, here we propose an intrinsically episodic, magnetically dominated jet model for the GRB central engine. Accumulation and eruption of free magnetic energy in the corona of a differentially rotating, turbulent accretion flow around a hyperaccreting black hole lead to ejections of episodic, magnetically dominated plasma blobs. These blobs are accelerated magnetically, collide with each other at large radii, trigger rapid magnetic reconnection and turbulence, efficient particle acceleration, and radiation, and power the observed episodic prompt gamma-ray emission from GRBs.

  8. Angular Scaling In Jets

    SciTech Connect (OSTI)

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC

    2012-02-17T23:59:59.000Z

    We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.

  9. ATLAS Jet Energy Scale

    E-Print Network [OSTI]

    D. Schouten; A. Tanasijczuk; M. Vetterli; for the ATLAS Collaboration

    2012-01-11T23:59:59.000Z

    Jets originating from the fragmentation of quarks and gluons are the most common, and complicated, final state objects produced at hadron colliders. A precise knowledge of their energy calibration is therefore of great importance at experiments at the Large Hadron Collider at CERN, while is very difficult to ascertain. We present in-situ techniques and results for the jet energy scale at ATLAS using recent collision data. ATLAS has demonstrated an understanding of the necessary jet energy corrections to within \\approx 4% in the central region of the calorimeter.

  10. Wave turbulent statistics in non-weak wave turbulence

    E-Print Network [OSTI]

    Naoto Yokoyama

    2011-05-08T23:59:59.000Z

    In wave turbulence, it has been believed that statistical properties are well described by the weak turbulence theory, in which nonlinear interactions among wavenumbers are assumed to be small. In the weak turbulence theory, separation of linear and nonlinear time scales derived from the weak nonlinearity is also assumed. However, the separation of the time scales is often violated even in weak turbulent systems where the nonlinear interactions are actually weak. To get rid of this inconsistency, closed equations are derived without assuming the separation of the time scales in accordance with Direct-Interaction Approximation (DIA), which has been successfully applied to Navier--Stokes turbulence. The kinetic equation of the weak turbulence theory is recovered from the DIA equations if the weak nonlinearity is assumed as an additional assumption. It suggests that the DIA equations is a natural extension of the conventional kinetic equation to not-necessarily-weak wave turbulence.

  11. Characterization of Relativistic MHD Turbulence

    E-Print Network [OSTI]

    Garrison, David

    2015-01-01T23:59:59.000Z

    The objective of this work is to understand if and how the characteristics of relativistic MHD turbulence may differ from those of nonrelativistic MHD turbulence. We accomplish this by studying the invariants in the relativistic case and comparing them to what we know of nonrelativistic turbulence. Although much work has been done to understand the dynamics of nonrelativistic systems (mostly for ideal incompressible fluids), there is minimal literature explicitly describing the dynamics of relativistic MHD turbulence. Many authors simply assume that relativistic turbulence has the same invariants and obeys the same inverse energy cascade as non-relativistic systems.

  12. Turbulent Combustion Luc Vervisch

    E-Print Network [OSTI]

    Kern, Michel

    ;19 "Perfect" combustion modes: Fuel + Oxidizer () Products Engines, gas turbines... Laboratory experiment1 Turbulent Combustion Modeling Luc Vervisch INSA de Rouen, IUF, CORIA-CNRS Quelques problèmes rencontrés en chimie numérique : Hydrologie - Combustion - Atmosphère 16 décembre, INRIA Rocquencourt #12

  13. Magnetic instability in a dilute circular rarefaction wave

    SciTech Connect (OSTI)

    Dieckmann, M. E. [Department of Science and Technology (ITN), Linkoping University, 60174 Norrkoping (Sweden); Sarri, G.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN (United Kingdom)

    2012-12-15T23:59:59.000Z

    The growth of magnetic fields in the density gradient of a rarefaction wave has been observed in simulations and in laboratory experiments. The thermal anisotropy of the electrons, which gives rise to the magnetic instability, is maintained by the ambipolar electric field. This simple mechanism could be important for the magnetic field amplification in astrophysical jets or in the interstellar medium ahead of supernova remnant shocks. The acceleration of protons and the generation of a magnetic field by the rarefaction wave, which is fed by an expanding circular plasma cloud, is examined here in form of a 2D particle-in-cell simulation. The core of the plasma cloud is modeled by immobile charges, and the mobile protons form a small ring close to the cloud's surface. The number density of mobile protons is thus less than that of the electrons. The protons of the rarefaction wave are accelerated to 1/10 of the electron thermal speed, and the acceleration results in a thermal anisotropy of the electron distribution in the entire plasma cloud. The instability in the rarefaction wave is outrun by a TM wave, which grows in the dense core distribution, and its magnetic field expands into the rarefaction wave. This expansion drives a secondary TE wave.

  14. Interactions of a Light Hypersonic Jet with a Non-Uniform Interstellar Medium

    E-Print Network [OSTI]

    Sutherland, R S

    2007-01-01T23:59:59.000Z

    We present three dimensional simulations of the interaction of a light hypersonic jet with an inhomogeneous thermal and turbulently supported disk in an elliptical galaxy. We model the jet as a light, supersonic non-relativistic flow with parameters selected to be consistent with a relativistic jet with kinetic power just above the FR1/FR2 break. We identify four generic phases in the evolution of such a jet with the inhomogeneous interstellar medium: 1) an initial ``flood and channel'' phase, where progress is characterized by high pressure gas finding changing weak points in the ISM, flowing through channels that form and re-form over time, 2) a spherical, energy-driven bubble phase, were the bubble is larger than the disk scale, but the jet remains fully disrupted close to the nucleus, 3) a rapid, jet break--out phase the where jet breaks free of the last dense clouds, becomes collimated and pierces the spherical bubble, and 4) a classical phase, the jet propagates in a momentum-dominated fashion leading t...

  15. IMPACT OF BOUNDARY-LAYER CUTTING AND FLOW CONDITIONING ON FREE-SURFACE BEHAVIOR IN TURBULENT LIQUID SHEETS

    E-Print Network [OSTI]

    California at San Diego, University of

    IMPACT OF BOUNDARY-LAYER CUTTING AND FLOW CONDITIONING ON FREE-SURFACE BEHAVIOR IN TURBULENT LIQUID dimension) = 1 cm into ambient air are compared with empirical correlations at a nearly prototypical term, for a well- conditioned jet but is not a substitute for well-designed flow conditioning. I

  16. Prediction of turbulent flow and local heat transfer in internally cooled turbine airfoils: the leading edge region

    E-Print Network [OSTI]

    Pontaza, Juan Pablo

    2013-02-22T23:59:59.000Z

    -Stokes equations and the energy equation in conjunction with a two-layer K-Epsilon isotropic eddy viscosity model and a near-wall Reynolds-Stress closure model. The fundamental cases of fully developed turbulent pipe flow and an axisymmetric jet impinging on a...

  17. On the properties of Circular-Beams

    E-Print Network [OSTI]

    Giuseppe Vallone

    2015-01-28T23:59:59.000Z

    Circular-Beams were introduced as a very general solution of the paraxial wave equation carrying Orbital Angular Momentum. Here we study their properties, by looking at their normalization and their expansion in terms of Laguerre-Gauss modes. We also study their far-field divergence and, for particular cases of the beam parameters, their possible experimental generation.

  18. Circular 57 Streptococcal Infections of Fish1

    E-Print Network [OSTI]

    Watson, Craig A.

    , and striped bass (Inglis et al. 1993). Strep has also been isolated from a variety of ornamental fishCircular 57 Streptococcal Infections of Fish1 Roy P.E. Yanong and Ruth Francis-Floyd2 1 of the common disease-causing bacteria of fish are Gram-negative (appear pink with a Gram stain

  19. Turbulent Reconnection and Its Implications

    E-Print Network [OSTI]

    Lazarian, Alex; Vishniac, Ethan T; Kowal, Grzegorz

    2015-01-01T23:59:59.000Z

    Magnetic reconnection is a process of magnetic field topology change, which is one of the most fundamental processes in magnetized plasmas. In most astrophysical environments the Reynolds numbers are large and therefore the transition to turbulence is inevitable. This turbulence must be taken into account for any theory of magnetic reconnection, since the initially laminar configurations can transit to the turbulence state, what is demonstrated by 3D high resolution numerical simulations. We discuss ideas of how turbulence can modify reconnection with the focus on the Lazarian & Vishniac (1999) reconnection model and present numerical evidence supporting the model and demonstrate that it is closely connected to the concept of Richardson diffusion and compatible with the Lagrangian dynamics of magnetized fluids. We point out that the Generalized Ohm's Law, that accounts for turbulent motion, predicts the subdominance of the microphysical plasma effects for a realistically turbulent media. We show that on o...

  20. Transition to turbulence in ferrofluids

    E-Print Network [OSTI]

    Altmeyer, Sebastian; Lai, Ying-Cheng

    2015-01-01T23:59:59.000Z

    It is known that in classical fluids turbulence typically occurs at high Reynolds numbers. But can turbulence occur at low Reynolds numbers? Here we investigate the transition to turbulence in the classic Taylor-Couette system in which the rotating fluids are manufactured ferrofluids with magnetized nanoparticles embedded in liquid carriers. We find that, in the presence of a magnetic field turbulence can occur at Reynolds numbers that are at least one order of magnitude smaller than those in conventional fluids. This is established by extensive computational ferrohydrodynamics through a detailed bifurcation analysis and characterization of behaviors of physical quantities such as the energy, the wave number, and the angular momentum through the bifurcations. A striking finding is that, as the magnetic field is increased, the onset of turbulence can be determined accurately and reliably. Our results imply that experimental investigation of turbulence can be greatly facilitated by using ferrofluids, opening up...

  1. Turbulence in Atomic Hydrogen

    E-Print Network [OSTI]

    A. Lazarian

    1998-04-02T23:59:59.000Z

    Understanding the properties of interstellar turbulence is a great intellectual challenge and the urge to solve this problem is partially motivated by a necessity to explain the star formation mystery. This review deals with a recently suggested inversion technique as applied to atomic hydrogen. This technique allows to determine 3D turbulence statistics through the variations of 21 cm intensity. We claim that a radio interferometer is an ideal tool for such a study as its visibility function is directly related to the statistics of galactic HI. Next, we show how galactic rotation curve can be used to study the turbulence slice by slice and relate the statistics given in galactic coordinates and in the velocity space. The application of the technique to HI data reveals a shallow spectrum of the underlying HI density that is not compatible with a naive Kolmogorov picture. We show that the random density corresponding to the found spectrum tends to form low contrast filaments that are elongated towards the observer.

  2. LDV measurement and Navier-Stokes computation of parallel jet mixing in a rectangular confinement

    SciTech Connect (OSTI)

    Kunz, R.F.; D`Amico, S.W.; Vassallo, P.F.; Zaccaria, M.A. [Knolls Atomic Power Lab., Schenectady, NY (United States); Aksoy, H.; So, R.M.C. [Arizona State Univ., Tempe, AZ (United States). Dept. of Mechanical and Aerospace Engineering

    1995-06-01T23:59:59.000Z

    Laser Doppler Velocimetry (LDV) measurements were taken in a rectangular confinement into which issues a row of parallel jets. Two-component measurements were taken with two optics orientations yielding three mean velocity components and four Reynolds stress components. As observed in isolated three dimensional wall bounded jets, the transverse diffusion of the jets is quite large. The data indicates that this rapid mixing process is due to strong secondary flows, transport of large inlet intensities and Reynolds stress anisotropy effects. Navier-Stokes analyses of this configuration underpredict the rate of transverse jet diffusion. Detailed numerical accuracy studies show that this is attributed to shortcomings in low-Reynolds number two-equation turbulence modelling. A low-Reynolds number full-Reynolds stress model is shown to provide improvement.

  3. NOAA Technical Report NMFS Circular 450 The Utility of Developmental

    E-Print Network [OSTI]

    #12;450 NOAA Technical Report NMFS Circular 450 The Utility of Developmental Osteology in Taxonomic Report NMFS Circular 450 The Utility of Developmental Osteology in Taxonomic and Systematic Studies .................................................................. .... 13 Scales and lateral line pores

  4. Policy Flash 2014-38 Federal Acquisition Circular (FAC) 2005...

    Broader source: Energy.gov (indexed) [DOE]

    8 Federal Acquisition Circular (FAC) 2005-76 Policy Flash 2014-38 Federal Acquisition Circular (FAC) 2005-76 Questions concerning this policy flash should be directed to Jason...

  5. POLICY FLASH 2014-31 Federal Acquisition Circulars (FACs) 2005...

    Office of Environmental Management (EM)

    POLICY FLASH 2014-31 Federal Acquisition Circulars (FACs) 2005-73 and 2005-74 POLICY FLASH 2014-31 Federal Acquisition Circulars (FACs) 2005-73 and 2005-74 Questions concerning...

  6. Jet Substructure by Accident

    E-Print Network [OSTI]

    Timothy Cohen; Eder Izaguirre; Mariangela Lisanti; Hou Keong Lou

    2013-04-23T23:59:59.000Z

    We propose a new search strategy for high-multiplicity hadronic final states. When new particles are produced at threshold, the distribution of their decay products is approximately isotropic. If there are many partons in the final state, it is likely that several will be clustered into the same large-radius jet. The resulting jet exhibits substructure, even though the parent states are not boosted. This "accidental" substructure is a powerful discriminant against background because it is more pronounced for high-multiplicity signals than for QCD multijets. We demonstrate how to take advantage of accidental substructure to reduce backgrounds without relying on the presence of missing energy. As an example, we present the expected limits for several R-parity violating gluino decay topologies. This approach allows for the determination of QCD backgrounds using data-driven methods, which is crucial for the feasibility of any search that targets signatures with many jets and suppressed missing energy.

  7. Jet Substructure by Accident

    E-Print Network [OSTI]

    Cohen, Timothy; Lisanti, Mariangela; Lou, Hou Keong

    2012-01-01T23:59:59.000Z

    We propose a new search strategy for high-multiplicity hadronic final states. When new particles are produced at threshold, the distribution of their decay products is approximately isotropic. If there are many partons in the final state, it is likely that several will be clustered into the same large-radius jet. The resulting jet exhibits substructure, even though the parent states are not boosted. This "accidental" substructure is a powerful discriminant against background because it is more pronounced for high-multiplicity signals than for QCD multijets. We demonstrate how to take advantage of accidental substructure to reduce backgrounds without relying on the presence of missing energy. As an example, we present the expected limits for several R-parity violating gluino decay topologies. This approach allows for the determination of QCD backgrounds using data-driven methods, which is crucial for the feasibility of any search that targets signatures with many jets and suppressed missing energy.

  8. Protostellar outflow-driven turbulence

    E-Print Network [OSTI]

    Christopher D. Matzner

    2007-01-01T23:59:59.000Z

    Protostellar outflows crisscross the regions of star cluster formation, stirring turbulence and altering the evolution of the forming cluster. We model the stirring of turbulent motions by protostellar outflows, building on an observation that the scaling law of supersonic turbulence implies a momentum cascade analogous to the energy cascade in Kolmogorov turbulence. We then generalize this model to account for a diversity of outflow strengths, and for outflow collimation, both of which enhance turbulence. For a single value of its coupling coefficient the model is consistent with turbulence simulations by Li & Nakamura and, plausibly, with observations of the NGC 1333 cluster-forming region. Outflow-driven turbulence is strong enough to stall collapse in cluster-forming regions for several crossing times, relieving the mismatch between star formation and turbulent decay rates. The predicted line-width-size scaling implies radial density indices between -1 and -2 for regions supported by outflow-driven turbulence, with a tendency for steeper profiles in regions that are more massive or have higher column densities.

  9. Organic vapor jet printing system

    DOE Patents [OSTI]

    Forrest, Stephen R

    2012-10-23T23:59:59.000Z

    An organic vapor jet printing system includes a pump for increasing the pressure of an organic flux.

  10. Supercomputers Capture Turbulence in the Solar Wind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Capture Turbulence in the Solar Wind Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space weather...

  11. Advanced Computational Methods for Turbulence and Combustion...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Advanced Computational Methods for Turbulence and Combustion Advanced Computational Methods for Turbulence and Combustion Bell.png Key Challenges: Development and application of...

  12. Simulation of lean premixed turbulent combustion

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    turbulent methane combustion. Proc. Combust. Inst. , 29:in premixed turbulent combustion. Proc. Combust. Inst. ,for zero Mach number combustion. Combust. Sci. Technol. ,

  13. PANS method of turbulence: simulation of high and low Reynolds number flows past a circular cylinder

    E-Print Network [OSTI]

    Lakshmipathy, Sunil

    2006-04-12T23:59:59.000Z

    cylinder are performed at ReD 140,000 and ReD 3900 using the PANS model. The high Reynolds number PANS results are compared with experimental results from Cantwell and Coles, Large Eddy Simulation results from Breuer, and Detached Eddy Simulation results...

  14. PANS turbulence model: investigation of computational and physical closure issues in flow past a circular cylinder

    E-Print Network [OSTI]

    Reyes, Dasia Ann

    2009-05-15T23:59:59.000Z

    p = P +pu (2.4) The cut-o can be arbitrary but the lter must commute with temporal and spatial di erentiation (Germano 1992). When the lter is applied, we get hVii = Ui and 7 hpi= P. However, this decomposition is unlike that of the statistical one... of the unresolved kinetic energy equation emerges. @ku @t +Uj @ku @xj = Pu u +Tku (2.19) This is the generalized form of the unresolved kinetic energy evolution equation with ku = 12 (Vi;Vj) where Pu = 12 (Vi;Vj) @Ui@xj . In PANS closure at the two-equation level...

  15. Circular, confined distribution for charged particle beams

    DOE Patents [OSTI]

    Garnett, Robert W. (Los Alamos, NM); Dobelbower, M. Christian (Toledo, OH)

    1995-01-01T23:59:59.000Z

    A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location.

  16. Circular, confined distribution for charged particle beams

    DOE Patents [OSTI]

    Garnett, R.W.; Dobelbower, M.C.

    1995-11-21T23:59:59.000Z

    A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location. 26 figs.

  17. Gasoline Jet Fuels

    E-Print Network [OSTI]

    Kemner, Ken

    C4n= Diesel Gasoline Jet Fuels C O C5: Xylose C6 Fermentation of sugars Biofuel "Nanobowls" are inorganic catalysts that could provide the selectivity for converting sugars to fuels IACT Proposes Synthetic, Inorganic Catalysts to Produce Biofuels Current Process

  18. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01T23:59:59.000Z

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  19. Jet quenching and elliptic flow

    E-Print Network [OSTI]

    A. K. Chaudhuri

    2007-08-29T23:59:59.000Z

    In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium, leading to suppressed production of high-$p_T$ hadrons. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. Explicit simulation of Au+Au collision with and without a quenching jet indicate that elliptic flow is greatly reduced in a jet event. The result can be used to identify the jet events in heavy ion collisions.

  20. Turbulence radiation interaction in Reynolds-averaged Navier-Stokes simulations of nonpremixed piloted turbulent laboratory-scale flames

    SciTech Connect (OSTI)

    Habibi, A.; Merci, B. [Department of Flow, Heat and Combustion Mechanics, Ghent University, B-9000 Ghent (Belgium); Roekaerts, D. [Delft University of Technology, Delft (Netherlands)

    2007-10-15T23:59:59.000Z

    Numerical simulation results are presented for two axisymmetric, nonluminous turbulent piloted jet diffusion flames: Sandia Flame D (SFD) and Delft Flame III (DFIII). Turbulence is represented by a Reynolds stress transport model, while chemistry is modeled by means of steady laminar flamelets. We use the preassumed PDF approach for turbulence-chemistry interaction. A weighted sum of gray gases model is used for the gas radiative properties. The radiative transfer equation is solved using the discrete ordinates method in the conservative finite-volume formulation. The radiative loss leads to a decrease in mean temperature, but does not significantly influence the flow and mixing fields, in terms either of mean values or of rms values of fluctuations. A systematic analysis of turbulence-radiation interaction (TRI) is carried out. By considering five different TRI formulations, and comparing also with a simple optically thin model, individual TRI contributions are isolated and quantified. For both flames, effects are demonstrated of (1) influence of temperature fluctuations on the mean Planck function, (2) temperature and composition fluctuations on the mean absorption coefficient, and (3) correlation between absorption coefficient and Planck function. The strength of the last effect is stronger in DFIII than in SFD, because of stronger turbulence-chemistry interaction and lower mean temperature in DFIII. The impact of the choice of TRI model on the prediction of the temperature-sensitive minor species NO is determined in a postprocessing step with fixed flow and mixing fields. Best agreement for NO is obtained using the most complete representation of TRI. (author)

  1. Advances in compressible turbulent mixing

    SciTech Connect (OSTI)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E. [eds.

    1992-01-01T23:59:59.000Z

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately.

  2. Observations of Edge Turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservation ofofEdge Turbulence

  3. Radiosonde measurements of turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared at 278, 298, and 323Program2 RadiometerTurbulence detection on

  4. Rapidity-Dependent Jet Vetoes

    E-Print Network [OSTI]

    Shireen Gangal; Maximilian Stahlhofen; Frank J. Tackmann

    2014-12-15T23:59:59.000Z

    Jet vetoes are a prominent part of the signal selection in various analyses at the LHC. We discuss jet vetoes for which the transverse momentum of a jet is weighted by a smooth function of the jet rapidity. With a suitable choice of the rapidity-weighting function, such jet-veto variables can be factorized and resummed allowing for precise theory predictions. They thus provide a complementary way to divide phase space into exclusive jet bins. In particular, they provide a natural and theoretically clean way to implement a tight veto on central jets with the veto constraint getting looser for jets at increasingly forward rapidities. We mainly focus our discussion on the 0-jet case in color-singlet processes, using Higgs production through gluon fusion as a concrete example. For one of our jet-veto variables we compare the resummed theory prediction at NLL'+NLO with the recent differential cross section measurement by the ATLAS experiment in the $H\\to\\gamma\\gamma$ channel, finding good agreement. We also propose that these jet-veto variables can be measured and tested against theory predictions in other SM processes, such as Drell-Yan, diphoton, and weak diboson production.

  5. Turbulence Effects at Small Scales

    E-Print Network [OSTI]

    A. Beresnyak; A. Lazarian

    2006-10-26T23:59:59.000Z

    It is most natural to assume that mysterious Small Ionized and Neutral Structures (SINS) indiffuse ISM arise from turbulence. There are two obvious problem with such an explanation, however. First of all, it is generally believed that at the small scales turbulence should be damped. Second, turbulence with Kolmogorov spectrum cannot be the responsible for the SINS. We consider, however, effects, that provide spectral index flatter than the Kolmogorov one and allow action at very small scales. These are the shocks that arise in high Mach number turbulence and transfer of energy to small scales by instabilities in cosmic rays. Our examples indicate that the origin of SINS may be discovered through systematic studies of astrophysical turbulence.

  6. SPH compressible turbulence

    E-Print Network [OSTI]

    J. J. Monaghan

    2002-04-08T23:59:59.000Z

    In this paper an SPH version of the alpha turbulence model devised by Holm and his colleagues is formulated for compressible flow with a resolution that varies in space and time. The alpha model involves two velocity fields. One velocity field is obtained from the momentum equation, the other by averaging this velocity field as in the version of SPH called XSPH. The particles (fluid elements) are moved with the averaged velocity. In analogy to the continuum alpha model we obtain a particle Lagrangian from which the SPH alpha equations can be derived. The system satisfies a discrete Kelvin circulation theorem identical to that obtained with no velocity averaging. In addition, the energy, linear and angular momentum are conserved. We show that the continuum equivalent of the SPH equations are identical to the continuum alpha model, and we conjecture that they will have the same desirable features of the continuum modelincluding the reduction of energy in the high wave number modes even when the dissipation is zero. Regardless of issues concerning turbulence modelling, the SPH alpha model is a powerful extension of the XSPH algorithm which reduces disorder at short length scales and retains the constants of the motion. The SPH alpha model is simple to implement.

  7. Experimental Study of Circular Laminar Confined Jets at Low Reynolds Numbers

    E-Print Network [OSTI]

    Diggavi, Suhas

    such as piping, heat exchangers, combustion chambers, mixers and bio-fluidics. - Insufficient experimental

  8. Long Term Tritium Trapping in TFTR and JET

    SciTech Connect (OSTI)

    C.H. Skinner; C.A. Gentile; K.M. Young; J.P. Coad; J.T. Hogan; R.-D. Penzhorn; and N. Bekris

    2001-07-24T23:59:59.000Z

    Tritium retention in TFTR [Tokamak Fusion Test Reactor] and JET [Joint European Torus] shows striking similarities and contrasts. In TFTR, 5 g of tritium were injected into circular plasmas over a 3.5 year period, mostly by neutral-beam injection. In JET, 35 g were injected into divertor plasmas over a 6 month campaign, mostly by gas puffing. In TFTR, the bumper limiter provided a large source of eroded carbon and a major part of tritium was co-deposited on the limiter and vessel wall. Only a small area of the co-deposit flaked off. In JET, the wall is a net erosion area, and co-deposition occurs principally in shadowed parts of the inner divertor, with heavy flaking. In both machines, the initial tritium retention, after a change from deuterium [D] to tritium [T] gas puffing, is high and is due to isotope exchange with deuterium on plasma-facing surfaces (dynamic inventory). The contribution of co-deposition is lower but cumulative, and is revealed by including periods of D fueling that reversed the T/D isotope exchange. Ion beam analysis of flakes from TFTR showed an atomic D/C ratio of 0.13 on the plasma facing surface, 0.25 on the back surface and 0.11 in the bulk. Data from a JET divertor tile showed a larger D/C ratio with 46% C, 30% D, 20% H and 4% O. Deuterium, tritium, and beryllium profiles have been measured and show a thin less than 50 micron co-deposited layer. Flakes retrieved from the JET vacuum vessel exhibited a high tritium release rate of 2e10 Bq/month/g. BBQ modeling of the effect of lithium on retention in TFTR showed overlapping lithium and tritium implantation and a 1.3x increase in local T retention.

  9. Measurements and modeling of soot formation and radiation in microgravity jet diffusion flames

    SciTech Connect (OSTI)

    Ku, J.C.; Tong, L. [Wayne State Univ., Detroit, MI (United States). Mechanical Engineering Dept.; Greenberg, P.S. [NASA Lewis Research Center, Cleveland, OH (United States). Microgravity Combustion Branch

    1996-12-31T23:59:59.000Z

    This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. On modeling, the authors have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed {beta}-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude-Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H{sub 2}O and CO{sub 2}. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar flames and turbulent jet flames. Predicted soot volume fraction results also agree with the data for 1-g and 0-g laminar jet flames as well as 1-g turbulent jet flames.

  10. Compound cooling flow turbulator for turbine component

    DOE Patents [OSTI]

    Lee, Ching-Pang; Jiang, Nan; Marra, John J; Rudolph, Ronald J

    2014-11-25T23:59:59.000Z

    Multi-scale turbulation features, including first turbulators (46, 48) on a cooling surface (44), and smaller turbulators (52, 54, 58, 62) on the first turbulators. The first turbulators may be formed between larger turbulators (50). The first turbulators may be alternating ridges (46) and valleys (48). The smaller turbulators may be concave surface features such as dimples (62) and grooves (54), and/or convex surface features such as bumps (58) and smaller ridges (52). An embodiment with convex turbulators (52, 58) in the valleys (48) and concave turbulators (54, 62) on the ridges (46) increases the cooling surface area, reduces boundary layer separation, avoids coolant shadowing and stagnation, and reduces component mass.

  11. Lamar Low-Level Jet Program Interim Report

    SciTech Connect (OSTI)

    Kelley, N.; Shirazi, M.; Jager, D.; Wilde, S.; Adams, J.; Buhl, M.; Sullivan, P.; Patton, E.

    2004-01-01T23:59:59.000Z

    This interim report presents the results to date from the Lamar Low-Level Jet Program (LLLJP) that has been established as joint effort among the U.S. Department of Energy (DOE), the National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory (NREL), and General Electric Wind Energy (GE Wind). The purpose of this project is to develop an understanding of the influence of nocturnal low-level jet streams on the inflow turbulence environment and the documenting of any potential operating impacts on current large wind turbines and the Low Wind Speed Turbine (LWST) designs of the future. A year's record of detailed nocturnal turbulence measurements has been collected from NREL instrumentation installed on the GE Wind 120-m tower in southeastern Colorado and supplemented with mean wind profile data collected using an acoustic wind profiler or SODAR (Sound Detection and Ranging). The analyses of measurements taken as part of a previous program conducted at the NWTC have been used to aid in the interpretation of the results of representative case studies of data collected from the GE Wind tower.

  12. Multipole Analysis of Circular Cylindircal Magnetic Systems

    SciTech Connect (OSTI)

    J Selvaggi

    2006-01-09T23:59:59.000Z

    This thesis deals with an alternate method for computing the external magnetic field from a circular cylindrical magnetic source. The primary objective is to characterize the magnetic source in terms of its equivalent multipole distribution. This multipole distribution must be valid at points close to the cylindrical source and a spherical multipole expansion is ill-equipped to handle this problem; therefore a new method must be introduced. This method, based upon the free-space Green's function in cylindrical coordinates, is developed as an alternative to the more familiar spherical harmonic expansion. A family of special functions, called the toroidal functions or Q-functions, are found to exhibit the necessary properties for analyzing circular cylindrical geometries. In particular, the toroidal function of zeroth order, which comes from the integral formulation of the free-space Green's function in cylindrical coordinates, is employed to handle magnetic sources which exhibit circular cylindrical symmetry. The toroidal functions, also called Q-functions, are the weighting coefficients in a ''Fourier series-like'' expansion which represents the free-space Green's function. It is also called a toroidal expansion. This expansion can be directly employed in electrostatic, magnetostatic, and electrodynamic problems which exhibit cylindrical symmetry. Also, it is shown that they can be used as an alternative to the Elliptic integral formulation. In fact, anywhere that an Elliptic integral appears, one can replace it with its corresponding Q-function representation. A number of problems, using the toroidal expansion formulation, are analyzed and compared to existing known methods in order to validate the results. Also, the equivalent multipole distribution is found for most of the solved problems along with its corresponding physical interpretation. The main application is to characterize the external magnetic field due to a six-pole permanent magnet motor in terms of its equivalent multipole distribution.

  13. Wave Decay in MHD Turbulence

    E-Print Network [OSTI]

    Andrey Beresnyak; Alex Lazarian

    2008-05-06T23:59:59.000Z

    We present a model for nonlinear decay of the weak wave in three-dimensional incompressible magnetohydrodynamic (MHD) turbulence. We show that the decay rate is different for parallel and perpendicular waves. We provide a general formula for arbitrarily directed waves and discuss particular limiting cases known in the literature. We test our predictions with direct numerical simulations of wave decay in three-dimensional MHD turbulence, and discuss the influence of turbulent damping on the development of linear instabilities in the interstellar medium and on other important astrophysical processes.

  14. Circular zig-zag scan video format

    DOE Patents [OSTI]

    Peterson, C.G.; Simmons, C.M.

    1992-06-09T23:59:59.000Z

    A circular, ziz-zag scan for use with vidicon tubes is disclosed. A sine wave is generated, rectified and its fourth root extracted. The fourth root, and its inverse, are used to generate horizontal ramp and sync signals. The fourth root is also used to generate a vertical sync signal, and the vertical sync signal, along with the horizontal sync signal, are used to generate the vertical ramp signal. Cathode blanking and preamplifier clamp signals are also obtained from the vertical sync signal. 10 figs.

  15. Federal Acquisition Circular 48 | Department of Energy

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAX POLICIES ANDIndustrial HygieneEnergyLead-acidPrimusContinued onCircular 48

  16. Federal Acquisition Circular WAC) 2001-24

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAX POLICIES ANDIndustrial HygieneEnergyLead-acidPrimusContinued onCircular 48

  17. Federal Acquisition Circulars 17, 18 and 20

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAX POLICIES ANDIndustrial HygieneEnergyLead-acidPrimusContinued onCircular 48

  18. A Family of Circular Bargmann Transforms

    E-Print Network [OSTI]

    Zouhair Mouayn

    2011-05-24T23:59:59.000Z

    When considering a charged particle evolving in the Poincar\\'e disk under influence of a uniform magnetic field with a strength proportional to +1, we construct for all hyperbolic Landau level \\epsilon^\\gamma_$m$ m = 4m(-m), m 2 Z+ \\[0, /2] a family of coherent states transforms labeled by (,m) and mapping isometrically square integrable functions on the unit circle with respect to the measure sin^\\gamma-2m (\\theta/2) d\\theta onto spaces of bound states of the particle. These transforms are called circular Bargmann transforms.

  19. Observations of turbulent fluxes and turbulence dynamics in the ocean surface boundary layer

    E-Print Network [OSTI]

    Gerbi, Gregory Peter

    2008-01-01T23:59:59.000Z

    This study presents observations of turbulence dynamics made during the low winds portion of the Coupled Boundary Layers and Air-Sea Transfer experiment (CBLAST-Low). Observations were made of turbulent fluxes, turbulent ...

  20. Jet initiation of PBX 9502

    SciTech Connect (OSTI)

    McAfee, J.M.

    1987-07-01T23:59:59.000Z

    This report details the progress of an effort to determine the quantitative aspects of the initiation of PBX 9502 (95% TATB, 5% Kel-F 800) by copper jets. The particular jet used was that produced by the LAW warhead (66-mm diameter, 42/sup 0/ angle cone, copper-lined, conical shaped charge). Fifteen experiments, in various configurations, have been fired to define the essential parameters for quantitatively measuring the jet performance and initiation of bare PBX 9502. 7 refs., 8 figs.

  1. Buoyant jet behavior in confined regions

    E-Print Network [OSTI]

    Fry, David J.

    1981-01-01T23:59:59.000Z

    Previous confined jet studies have emphasized the behavior of non-buoyant jets inside ducts or near plane boundaries (Coanda effect). Buoyancy, however, is a major factor in the confined jet behavior experienced in many ...

  2. Using Circular Programs to Deforest in Accumulating Parameters

    E-Print Network [OSTI]

    Eckmiller, Rolf

    Using Circular Programs to Deforest in Accumulating Parameters Janis Voigtl¨ander (voigt) deforestation, tree transducers CCS categories and subject descriptors: D.1.1 [Programming Techniques

  3. Comparative study of micromixing models in transported scalar PDF simulations of turbulent nonpremixed bluff body flames

    SciTech Connect (OSTI)

    Merci, Bart [Department of Flow, Heat and Combustion Mechanics, Ghent University-UGent, Ghent (Belgium); Roekaerts, Dirk [Department of Multi-Scale Physics, Delft University of Technology, Delft (Netherlands); Naud, Bertrand [CIEMAT, Madrid (Spain); Pope, Stephen B. [Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY (United States)

    2006-07-15T23:59:59.000Z

    Numerical simulation results are presented for turbulent jet diffusion flames with various levels of turbulence-chemistry interaction, stabilized behind a bluff body (Sydney Flames HM1-3). Interaction between turbulence and combustion is modeled with the transported joint-scalar PDF approach. The mass density function transport equation is solved in a Lagrangian manner. A second-moment-closure turbulence model is applied to obtain accurate mean flow and turbulent mixing fields. The behavior of two micromixing models is discussed: the Euclidean minimum spanning tree model and the modified Curl coalescence dispersion model. The impact of the micromixing model choice on the results in physical space is small, although some influence becomes visible as the amount of local extinction increases. Scatter plots and profiles of conditional means and variances of thermochemical quantities, conditioned on the mixture fraction, are discussed both within and downstream of the recirculation region. A distinction is made between local extinction and incomplete combustion, based on the CO species mass fraction. The differences in qualitative behavior between the micromixing models are explained and quantitative comparison to experimental data is made. (author)

  4. Mercury Jet Studies Tristan Davenne

    E-Print Network [OSTI]

    McDonald, Kirk

    Mercury Jet Studies Tristan Davenne Rutherford Appleton Laboratory Joint UKNF, INO, UKIERI meeting mercury target and reported a radial velocity at surface of mercury jet due to proton beam is 36m/s #12;Numerical simulation of Sievers & Pugnat Result Click on image above to watch video of 2cm mercury target

  5. OPENING ANGLES OF COLLAPSAR JETS

    SciTech Connect (OSTI)

    Mizuta, Akira; Ioka, Kunihito [Theory Center, Institute of Particle and Nuclear Studies, KEK, Tsukuba 305-0801 (Japan)

    2013-11-10T23:59:59.000Z

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by ?{sub j} ? 1/5?{sub 0} and infer the initial Lorentz factor of the jet at the central engine, ?{sub 0}, is a few for existing observations of ?{sub j}. The jet keeps the Lorentz factor low inside the star by converging cylindrically via collimation shocks under the cocoon pressure and accelerates at jet breakout before the free expansion to a hollow-cone structure. In this new picture, the GRB duration is determined by the sound crossing time of the cocoon, after which the opening angle widens, reducing the apparent luminosity. Some bursts violating the maximum opening angle ?{sub j,{sub max}} ? 1/5 ? 12° imply the existence of a baryon-rich sheath or a long-acting jet. We can explain the slopes in both Amati and Yonetoku spectral relations using an off-centered photosphere model, if we make only one assumption that the total jet luminosity is proportional to the initial Lorentz factor of the jet. We also numerically calibrate the pre-breakout model (Bromberg et al.) for later use.

  6. Introduction to statistical turbulence modelling. Overview, RWTH Aachen, 08./09.03.2010 Introduction to statistical turbulence modelling

    E-Print Network [OSTI]

    transfer of ­ Momentum Turbulent (Reynolds) stresses ­ Heat Turbulent heat flux ­ Mass Turbulent: Fundamental equations · Averaging · Flow equations · Turbulence equations Part II: Characteristics, RWTH Aachen, 08.03.2010 Reynolds' experiment: Inject dye into pipe flow Observe filament at different

  7. Simplified expansions for radiation from a baffled circular piston

    E-Print Network [OSTI]

    Mast, T. Douglas

    Simplified expansions for radiation from a baffled circular piston T. Douglas Mast Department from a baffled circular piston continues be an active area of investigation, both as a canonical computations of piston fields in lossless and attenuative fluid media. For the region r a, where

  8. A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation

    SciTech Connect (OSTI)

    McKinney, Jonathan C.; Uzdensky, Dmitri A.; ,

    2012-03-14T23:59:59.000Z

    Prompt gamma-ray burst (GRB) emission requires some mechanism to dissipate an ultrarelativistic jet. Internal shocks or some form of electromagnetic dissipation are candidate mechanisms. Any mechanism needs to answer basic questions, such as what is the origin of variability, what radius does dissipation occur at, and how does efficient prompt emission occur. These mechanisms also need to be consistent with how ultrarelativistic jets form and stay baryon pure despite turbulence and electromagnetic reconnection near the compact object and despite stellar entrainment within the collapsar model. We use the latest magnetohydrodynamical models of ultrarelativistic jets to explore some of these questions in the context of electromagnetic dissipation due to the slow collisional and fast collisionless reconnection mechanisms, as often associated with Sweet-Parker and Petschek reconnection, respectively. For a highly magnetized ultrarelativistic jet and typical collapsar parameters, we find that significant electromagnetic dissipation may be avoided until it proceeds catastrophically near the jet photosphere at large radii (r {approx} 10{sup 13}-10{sup 14}cm), by which the jet obtains a high Lorentz factor ({gamma} {approx} 100-1000), has a luminosity of L{sub j} {approx} 10{sup 50}-10{sup 51} erg s{sup -1}, has observer variability timescales of order 1s (ranging from 0.001-10s), achieves {gamma}{theta}{sub j} {approx} 10-20 (for opening half-angle {theta}{sub j}) and so is able to produce jet breaks, and has comparable energy available for both prompt and afterglow emission. A range of model parameters are investigated and simplified scaling laws are derived. This reconnection switch mechanism allows for highly efficient conversion of electromagnetic energy into prompt emission and associates the observed prompt GRB pulse temporal structure with dissipation timescales of some number of reconnecting current sheets embedded in the jet. We hope this work helps motivate the development of self-consistent radiative compressible relativistic reconnection models.

  9. Circularization of Tidally Disrupted Stars around Spinning Supermassive Black Holes

    E-Print Network [OSTI]

    Hayasaki, Kimitake; Loeb, Abraham

    2015-01-01T23:59:59.000Z

    We study the circularization of tidally disrupted stars on bound orbits around spinning supermassive black holes by performing three-dimensional smoothed particle hydrodynamic simulations with Post-Newtonian corrections. Our simulations reveal that debris circularization depends sensitively on the efficiency of radiative cooling. There are two stages in debris circularization if radiative cooling is inefficient: first, the stellar debris streams self-intersect due to relativistic apsidal precession; shocks at the intersection points thermalize orbital energy and the debris forms a geometrically thick, ring-like structure around the black hole. The ring rapidly spreads via viscous diffusion, leading to the formation of a geometrically thick accretion disk. In contrast, if radiative cooling is efficient, the stellar debris circularizes due to self-intersection shocks and forms a geometrically thin ring-like structure. In this case, the dissipated energy can be emitted during debris circularization as a precurso...

  10. Assessment of TurbulenceChemistry Interaction in Hypersonic Turbulent Boundary Layers

    E-Print Network [OSTI]

    Martín, Pino

    Assessment of Turbulence­Chemistry Interaction in Hypersonic Turbulent Boundary Layers L. Duan of the turbulence­chemistry interaction are performed in hypersonic turbulent boundary layers using direct numerical simulation flowfields under typical hypersonic conditions representative of blunt-body and slender- body

  11. Effect of Finite-rate Chemical Reactions on Turbulence in Hypersonic Turbulent Boundary Layers

    E-Print Network [OSTI]

    Martín, Pino

    Effect of Finite-rate Chemical Reactions on Turbulence in Hypersonic Turbulent Boundary Layers Lian on future air-breathing hypersonic cruise vehicles will be turbulent and chemically reacting. To aid the design of such vehicles, a greater understanding of turbulent hypersonic flows is needed. Although

  12. Selected problems in turbulence theory and modeling

    E-Print Network [OSTI]

    Jeong, Eun-Hwan

    2004-09-30T23:59:59.000Z

    Three different topics of turbulence research that cover modeling, theory and model computation categories are selected and studied in depth. In the first topic, "velocity gradient dynamics in turbulence" (modeling), the Lagrangian linear diffusion...

  13. Turbulence and Magnetic Fields in Clouds

    E-Print Network [OSTI]

    Shantanu Basu

    2004-11-15T23:59:59.000Z

    We discuss several categories of models which may explain the IMF, including the possible role of turbulence and magnetic fields.

  14. Stimulated Neutrino Transformation Through Turbulence

    E-Print Network [OSTI]

    Kelly M. Patton; James P. Kneller; Gail C. McLaughlin

    2014-04-15T23:59:59.000Z

    We derive an analytical solution for the flavor evolution of a neutrino through a turbulent density profile which is found to accurately predict the amplitude and transition wavelength of numerical solutions on a case-by-case basis. The evolution is seen to strongly depend upon those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. Transitions are strongly enhanced by those Fourier modes in the turbulence which are approximately the same as the splitting between neutrino eigenvalues. We also find a suppression of transitions due to the long wavelength modes when the ratio of their amplitude and the wavenumber is of order, or greater than, the first root of the Bessel function $J_0$.

  15. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, S.P.

    1999-03-02T23:59:59.000Z

    A dispenser is disclosed for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 {micro}m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (ca. 200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments. 4 figs.

  16. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, Steve P. (Livermore, CA)

    1999-03-02T23:59:59.000Z

    A dispenser for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 .mu.m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (.about.200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments.

  17. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, Jr., Edward P. (Idaho Falls, ID)

    1999-01-01T23:59:59.000Z

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed therebetween. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock.

  18. TURBULENCE IN SUPERSONIC AND HYPERSONIC BOUNDARY LAYERS

    E-Print Network [OSTI]

    Martín, Pino

    TURBULENCE IN SUPERSONIC AND HYPERSONIC BOUNDARY LAYERS Alexander J. Smits and M. Pino Martin in supersonic and hypersonic flow where the effects of compressibility have a direct influence on the turbulence. Experimental and DNS results are presented and compared. Key words: Turbulence, supersonic, hypersonic, shocks

  19. Numerical Study of a Turbulent Hydraulic Jump

    E-Print Network [OSTI]

    Zhao, Qun

    Numerical Study of a Turbulent Hydraulic Jump Qun Zhao, Shubhra Misra, Ib. A. Svendsen and James T of a Turbulent Hydraulic Jump ­ p.1/14 #12;Objective Our ultimate goal is to study the breaking waves. Numerical Study of a Turbulent Hydraulic Jump ­ p.2/14 #12;A moving bore Qiantang Bore China (Courtesy of Dr J

  20. Stability, Energetics, and Turbulent Transport in

    E-Print Network [OSTI]

    Torquato, Salvatore

    fields" Department of Astrophysical Sciences Spring Colloquium Steve Cowley (UK Atomic Energy Authority of solar-wind turbulence" Chris Chen (UC Berkeley) 2:40pm "Energy spectra in MHD turbulenceStability, Energetics, and Turbulent Transport in Astrophysical, Fusion, and Solar Plasmas 8

  1. Jets in heavy ion collisions with ATLAS

    E-Print Network [OSTI]

    Martin Spousta; for the ATLAS Collaboration

    2012-11-14T23:59:59.000Z

    The energy loss of high-p_T partons provides insight into the transport properties of the medium created in relativistic heavy ion collisions. Evidence for this energy loss was first experimentally established through observation of high-p_T hadron suppression at RHIC. More recently, measurements of fully reconstructed jets have been performed at the LHC. In this summary the latest experimental results from the ATLAS collaboration on jet suppression are presented. In particular the jet suppression in inclusive jet yields, path length dependence of the jet suppression, photon-jet and Z^0-jet correlations, heavy flavor suppression, and jet fragmentation are discussed. These results establish qualitative features of the jet quenching mechanism as experimental fact and provide constraints on models of jet energy loss.

  2. Turbulence transport with nonlocal interactions

    SciTech Connect (OSTI)

    Linn, R.R.; Clark, T.T.; Harlow, F.H.; Turner, L.

    1998-03-01T23:59:59.000Z

    This preliminary report describes a variety of issues in turbulence transport analysis with particular emphasis on closure procedures that are nonlocal in wave-number and/or physical space. Anomalous behavior of the transport equations for large scale parts of the turbulence spectrum are resolved by including the physical space nonlocal interactions. Direct and reverse cascade processes in wave-number space are given a much richer potential for realistic description by the nonlocal formulations. The discussion also describes issues, many still not resolved, regarding new classes of self-similar form functions.

  3. How to calibrate the jet energy scale?

    SciTech Connect (OSTI)

    Hatakeyama, K.; /Rockefeller U.

    2006-01-01T23:59:59.000Z

    Top quarks dominantly decay into b-quark jets and W bosons, and the W bosons often decay into jets, thus the precise determination of the jet energy scale is crucial in measurements of many top quark properties. I present the strategies used by the CDF and D0 collaborations to determine the jet energy scale. The various cross checks performed to verify the determined jet energy scale and evaluate its systematic uncertainty are also discussed.

  4. Latest jet results from the Tevatron

    SciTech Connect (OSTI)

    Price, Darren D.

    2010-05-01T23:59:59.000Z

    A brief overview of the latest status of jet physics studies at the Tevatron in proton-antiproton collisions at {radical}s = 1.96 TeV is presented. In particular, measurements of the inclusive jet production cross-section, dijet production and searches for new physics, the ratio of the 3-jet to 2-jet production cross-sections, and the three-jet mass are discussed.

  5. Rayleigh Test for Randomness of Circular Data

    E-Print Network [OSTI]

    D. Wilkie

    1983-01-01T23:59:59.000Z

    Critical values of the,Rayleigh test for testing whether the population of circular data from which a sample is drawn differs from randomness are sometimes presented in an inconvenient form (Batschelet, 1981) which makes it necessary to interpolate to obtain a value at a chosen probability level. Even when the values are presented at fixed probability levels (Mardia, 1972) it can be useful for computer programming and other purposes to have a simple expression that describes the tables. According to Mardia (1972) a good approximation, based on the work of Pearson (1906) and Greenwood and Durand (1955) for P = P (n R '>K), where is the mean resultant vector of n unit vectors, is given by A study of the tabulated critical values of R reveals that K is quite well represented by a linear function of over a wide range of n for each probability level P (Fig. 1). Substituting K =A t B/n in (1) yields so we choose A =-1nP and B = (2A- A2)/4. ~husapproximate critical values ofnR2 are given by

  6. Challenges for highest energy circular colliders

    E-Print Network [OSTI]

    Benedikt, M; Wenninger, J; Zimmermann, F

    2014-01-01T23:59:59.000Z

    A new tunnel of 80–100 km circumference could host a 100 TeV centre-of-mass energy-frontier proton collider (FCC-hh/VHE-LHC), with a circular lepton collider (FCCee/TLEP) as potential intermediate step, and a leptonhadron collider (FCC-he) as additional option. FCC-ee, operating at four different energies for precision physics of the Z, W, and Higgs boson and the top quark, represents a significant push in terms of technology and design parameters. Pertinent R&D efforts include the RF system, topup injection scheme, optics design for arcs and final focus, effects of beamstrahlung, beam polarization, energy calibration, and power consumption. FCC-hh faces other challenges, such as high-field magnet design, machine protection and effective handling of large synchrotron radiation power in a superconducting machine. All these issues are being addressed by a global FCC collaboration. A parallel design study in China prepares for a similar, but smaller collider, called CepC/SppC.

  7. Radial flow pulse jet mixer

    DOE Patents [OSTI]

    VanOsdol, John G.

    2013-06-25T23:59:59.000Z

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  8. Strategic Technology JET PROPULSION LABORATORY

    E-Print Network [OSTI]

    Waliser, Duane E.

    Strategic Technology Directions JET PROPULSION LABORATORY National Aeronautics and Space Administration 2 0 0 9 #12;© 2009 California Institute of Technology. Government sponsorship acknowledged. #12;Strategic Technology Directions 2009 offers a distillation of technologies, their links to space missions

  9. A spintronic source of circularly polarized single photons

    E-Print Network [OSTI]

    Asshoff, Pablo; Kalt, Heinz; Hetterich, Michael

    2011-01-01T23:59:59.000Z

    We present a spintronic single photon source which emits circularly polarized light, where the helicity is determined by an applied magnetic field. Photons are emitted from an InGaAs quantum dot inside an electrically operated spin light-emitting diode, which comprises the diluted magnetic semiconductor ZnMnSe. The circular polarization degree of the emitted light is high, reaching 83% at an applied magnetic field of 2T and 96% at 6 T. Autocorrelation traces recorded in pulsed operation mode prove the emitted light to be antibunched. The two circular polarization states could be used for representing quantum states |0> and |1> in quantum cryptography implementations.

  10. Perpendicular ion acceleration in whistler turbulence

    SciTech Connect (OSTI)

    Saito, S. [Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8601 (Japan)] [Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8601 (Japan); Nariyuki, Y. [Faculty of Human Development, University of Toyama, 3190, Toyama 930-8555 (Japan)] [Faculty of Human Development, University of Toyama, 3190, Toyama 930-8555 (Japan)

    2014-04-15T23:59:59.000Z

    Whistler turbulence is an important contributor to solar wind turbulence dissipation. This turbulence contains obliquely propagating whistler waves at electron scales, and these waves have electrostatic components perpendicular to the mean magnetic field. In this paper, a full kinetic, two-dimensional particle-in-cell simulation shows that whistler turbulence can accelerate ions in the direction perpendicular to the mean magnetic field. When the ions pass through wave-particle resonances region in the phase space during their cyclotron motion, the ions are effectively accelerated in the perpendicular direction. The simulation results suggest that whistler turbulence contributes to the perpendicular heating of ions observed in the solar wind.

  11. Numerical Simulations of Bouncing Jets

    E-Print Network [OSTI]

    Bonito, Andrea; Lee, Sanghyun

    2015-01-01T23:59:59.000Z

    Bouncing jets are fascinating phenomenons occurring under certain conditions when a jet impinges on a free surface. This effect is observed when the fluid is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs also for non-Newtonian fluids when the jets falls in a vessel at rest containing the same fluid. We investigate numerically the impact of the experimental setting and the rheological properties of the fluid on the onset of the bouncing phenomenon. Our investigations show that the occurrence of a thin lubricating layer of air separating the jet and the rest of the liquid is a key factor for the bouncing of the jet to happen. The numerical technique that is used consists of a projection method for the Navier-Stokes system coupled with a level set formulation for the representation of the interface. The space approximation is done with adaptive finite elements. Adaptive refinement is shown to be very important to capture the thin layer of air that is responsible for the bouncing.

  12. Turbulent Compressibilty of Protogalactic Gas

    E-Print Network [OSTI]

    John Scalo; Anirban Biswas

    2001-11-09T23:59:59.000Z

    The star formation rate in galaxies should be related to the fraction of gas that can attain densities large enough for gravitational collapse. In galaxies with a turbulent interstellar medium, this fraction is controlled by the effective barotropic index $gamma = dlog P/dlog (rho)$ which measures the turbulent compressibility. When the cooling timescale is smaller than the dynamical timescale, gamma can be evaluated from the derivatives of cooling and heating functions, using the condition of thermal equilibrium. We present calculations of gamma for protogalaxies in which the metal abundance is so small that H_2 and HD cooling dominates. For a heating rate independent of temperature and proportional to the first power of density, the turbulent gas is relatively "hard", with $gamma >= 1$, at large densities, but moderately "soft", $gamma <= 0.8$, at densities below around $10^4 cm^(-3)$. At low temperatures the density probability distribution should fall ra pidly for densities larger than this value, which corresponds physically to the critical density at which collisional and radiative deexcitation rate s of HD are equal. The densities attained in turbulent protogalaxies thus depend on the relatively large deuterium abundance in our universe. We expect the same physical effect to occur in higher metallicity gas with different coolants. The case in which adiabatic (compressional) heating due to cloud collapse dominates is also discussed, and suggests a criterion for the maximum mass of Population III stars.

  13. SIMULTANEOUS MEASUREMENT OF CIRCULAR DICHROISM AND FLUORESCENCE POLARIZATION ANISOTROPY.

    SciTech Connect (OSTI)

    SUTHERLAND,J.C.

    2002-01-19T23:59:59.000Z

    Circular dichroism and fluorescence polarization anisotropy are important tools for characterizing biomolecular systems. Both are used extensively in kinetic experiments involving stopped- or continuous flow systems as well as titrations and steady-state spectroscopy. This paper presents the theory for determining circular dichroism and fluorescence polarization anisotropy simultaneously, thus insuring the two parameters are recorded under exactly the same conditions and at exactly the same time in kinetic experiments. The approach to measuring circular dichroism is that used in almost all conventional dichrographs. Two arrangements for measuring fluorescence polarization anisotropy are described. One uses a single fluorescence detector and signal processing with a lock-in amplifier that is similar to the measurement of circular dichroism. The second approach uses classic ''T'' format detection optics, and thus can be used with conventional photon-counting detection electronics. Simple extensions permit the simultaneous measurement of the absorption and excitation intensity corrected fluorescence intensity.

  14. Binary Black Holes in Quasi-Stationary Circular Orbits

    E-Print Network [OSTI]

    Brian D. Baker

    2002-05-18T23:59:59.000Z

    We propose a method of determining solutions to the constraint equations of General Relativity approximately describing binary black holes in quasi-stationary circular orbits. Black holes with arbitrary linear momenta are constructed in the manner suggested by Brandt and Brugmann. The quasi-stationary circular orbits are determined by local minima in the ADM mass in a manner similar to Baumgarte and Cook; however, rather than fixing the area of the apparent horizon, we fix the value of the bare masses of the holes. We numerically generate an evolutionary sequence of quasi-stationary circular orbits up to and including the innermost stable circular orbit. We compare our results with post-Newtonian expectations as well as the results of Cook and Baumgarte. We also generate additional numerical results describing the dynamics of the geometry due to the emission of gravitational radiation.

  15. Plasma jet ignition device

    DOE Patents [OSTI]

    McIlwain, Michael E. (Franklin, MA); Grant, Jonathan F. (Wayland, MA); Golenko, Zsolt (North Reading, MA); Wittstein, Alan D. (Fairfield, CT)

    1985-01-15T23:59:59.000Z

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  16. Analysis of transverse apertures in a circular waveguide

    E-Print Network [OSTI]

    Eastham, Gary Bryan

    1989-01-01T23:59:59.000Z

    of a transverse aperture will be extremely useful in the design of coupled cavity resonators and circular cavity backed resonant aperture antennas. B. l. iterature Review Many authors have investigated the effects of apertures in both the transverse... 1989 Major Subject: Electrical Engineering ANALYSIS OF TRANSVERSE APERTURES IN A CIRCULAR WAVEGUIDE A Thesis GARY BRYAN EASTHAM Approved as to style and content by: Kai Chang (Chair of Committee) Brian D. Young (Member) Donal L. Parker...

  17. Structure of Turbulence in Katabatic Flows below and above the Wind-Speed Maximum

    E-Print Network [OSTI]

    Grachev, Andrey A; Di Sabatino, Silvana; Fernando, Harindra J S; Pardyjak, Eric R; Fairall, Christopher W

    2015-01-01T23:59:59.000Z

    Measurements of small-scale turbulence made over the complex-terrain atmospheric boundary layer during the MATERHORN Program are used to describe the structure of turbulence in katabatic flows. Turbulent and mean meteorological data were continuously measured at multiple levels at four towers deployed along the East lower slope (2-4 deg) of Granite Mountain. The multi-level observations made during a 30-day long MATERHORN-Fall field campaign in September-October 2012 allowed studying of temporal and spatial structure of katabatic flows in detail, and herein we report turbulence and their variations in katabatic winds. Observed vertical profiles show steep gradients near the surface, but in the layer above the slope jet the vertical variability is smaller. It is found that the vertical (normal to the slope) momentum flux and horizontal (along the slope) heat flux in a slope-following coordinate system change their sign below and above the wind maximum of a katabatic flow. The vertical momentum flux is directed...

  18. Inclusion of turbulence in solar modeling

    E-Print Network [OSTI]

    L. H. Li; F. J. Robinson; P. Demarque; S. Sofia; D. B. Guenther

    2001-11-07T23:59:59.000Z

    The general consensus is that in order to reproduce the observed solar p-mode oscillation frequencies, turbulence should be included in solar models. However, until now there has not been any well-tested efficient method to incorporate turbulence into solar modeling. We present here two methods to include turbulence in solar modeling within the framework of the mixing length theory, using the turbulent velocity obtained from numerical simulations of the highly superadiabatic layer of the sun at three stages of its evolution. The first approach is to include the turbulent pressure alone, and the second is to include both the turbulent pressure and the turbulent kinetic energy. The latter is achieved by introducing two variables: the turbulent kinetic energy per unit mass, and the effective ratio of specific heats due to the turbulent perturbation. These are treated as additions to the standard thermodynamic coordinates (e.g. pressure and temperature). We investigate the effects of both treatments of turbulence on the structure variables, the adiabatic sound speed, the structure of the highly superadiabatic layer, and the p-mode frequencies. We find that the second method reproduces the SAL structure obtained in 3D simulations, and produces a p-mode frequency correction an order of magnitude better than the first method.

  19. Transport enhancement and suppression in turbulent magnetic reconnection: A self-consistent turbulence model

    SciTech Connect (OSTI)

    Yokoi, N. [Institute of Industrial Science, University of Tokyo, Tokyo (Japan)] [Institute of Industrial Science, University of Tokyo, Tokyo (Japan); Higashimori, K.; Hoshino, M. [Department of Earth and Planetary Science, University of Tokyo, Tokyo (Japan)] [Department of Earth and Planetary Science, University of Tokyo, Tokyo (Japan)

    2013-12-15T23:59:59.000Z

    Through the enhancement of transport, turbulence is expected to contribute to the fast reconnection. However, the effects of turbulence are not so straightforward. In addition to the enhancement of transport, turbulence under some environment shows effects that suppress the transport. In the presence of turbulent cross helicity, such dynamic balance between the transport enhancement and suppression occurs. As this result of dynamic balance, the region of effective enhanced magnetic diffusivity is confined to a narrow region, leading to the fast reconnection. In order to confirm this idea, a self-consistent turbulence model for the magnetic reconnection is proposed. With the aid of numerical simulations where turbulence effects are incorporated in a consistent manner through the turbulence model, the dynamic balance in the turbulence magnetic reconnection is confirmed.

  20. Coupling of twin rectangular supersonic jets

    E-Print Network [OSTI]

    Raman, G.; Taghavi, Ray

    1998-01-01T23:59:59.000Z

    Twin jet plumes on aircraft can couple, producing dynamic pressures significant enough to cause structural fatigue. For closely spaced jets with a moderate aspect ratio (e.g. 5), previous work has established that two ...

  1. The Georgi Algorithms of Jet Clustering

    E-Print Network [OSTI]

    Shao-Feng Ge

    2014-08-30T23:59:59.000Z

    We reveal the direct link between the jet clustering algorithms recently proposed by Howard Georgi and parton shower kinematics, providing sound support from the theoretical side. The kinematics of this class of elegant algorithms is explored systematically and the jet function is generalized to $J^{(n)}_\\beta$ with a jet function index $n$. Based on three basic requirements that the result of jet clustering is process-independent, for softer subjets the inclusion cone is larger, and that the cone size cannot be too large in order to avoid mixing different jets, we derive constraints on the jet function index $n$ and the jet function parameter $\\beta$ which are closely related to phase space boundaries. Finally, we demonstrate that the jet algorithm is boost invariant.

  2. Theoretical and Experimental Simulation of Accident Scenarios of the JET Cryogenic Components Part I: The JET In-vessel Cryopump

    E-Print Network [OSTI]

    Theoretical and Experimental Simulation of Accident Scenarios of the JET Cryogenic Components Part I: The JET In-vessel Cryopump

  3. Theoretical and Experimental Simulation of Accident Scenarios of the JET Cryogenic Components Part II: The JET LHCD Cryopump

    E-Print Network [OSTI]

    Theoretical and Experimental Simulation of Accident Scenarios of the JET Cryogenic Components Part II: The JET LHCD Cryopump

  4. Advanced thermally stable jet fuels

    SciTech Connect (OSTI)

    Schobert, H.H.

    1999-01-31T23:59:59.000Z

    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume (Sections 1 through 5).

  5. Jet physics at HERA, Tevatron and LHC

    E-Print Network [OSTI]

    C. Royon

    2008-11-10T23:59:59.000Z

    In this short report, we discuss the Jet Physics results and perspectives at HERA, Tevatron and LHC.

  6. Inclusive jet production at the Tevatron

    SciTech Connect (OSTI)

    Norniella, Olga; /Barcelona, IFAE

    2006-08-01T23:59:59.000Z

    Preliminary results on inclusive jet production in proton-antiproton collisions at {radical}s = 1.96 TeV based on 1 fb{sup -1} of CDF Run II data are presented. Measurements are preformed using different jet algorithms in a wide range of jet transverse momentum and jet rapidity. The measured cross sections are compared to next-to-leading order perturbative QCD calculations

  7. Mimicking a turbulent signal: sequential multiaffine processes

    E-Print Network [OSTI]

    L. Biferale; G. Boffetta; A. Celani; A. Crisanti; A. Vulpiani

    1997-11-03T23:59:59.000Z

    An efficient method for the construction of a multiaffine process, with prescribed scaling exponents, is presented. At variance with the previous proposals, this method is sequential and therefore it is the natural candidate in numerical computations involving synthetic turbulence. The application to the realization of a realistic turbulent-like signal is discussed in detail. The method represents a first step towards the realization of a realistic spatio-temporal turbulent field.

  8. Two techniques for forecasting clear air turbulence

    E-Print Network [OSTI]

    Arbeiter, Randolph George

    2012-06-07T23:59:59.000Z

    for the height of the 200- and )00-mb pressure surfaces associated with nonturbulent and turbulent cases . . . . . . o. . . . . o o ~ o ~ . ~ . 17 4. Empirical frequency distributions for the temperature of the 200- and 300-mb pressure surfaces associated... with nonturbulent and turbulent areas. . . . . . ~ . . . . . ~ . ~ ~ Empirical frequency distributions of the zonal wind component on the 200- and 300-mb press- ure surfaces associated with nonturbulent and turbulent areas . . . . . . . . . . . . ~ ~ 20...

  9. Effect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent

    E-Print Network [OSTI]

    Martín, Pino

    Effect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent Boundary Layers) of reacting hypersonic turbulent boundary layers at conditions typical of reen- try vehicles. Surface heat in designing hypersonic vehicles is to predict aerothermo- dynamic heating. When the boundary layer

  10. Study of turbulence-chemistry interaction in hypersonic turbulent boundary layers

    E-Print Network [OSTI]

    Martín, Pino

    Study of turbulence-chemistry interaction in hypersonic turbulent boundary layers Lian Duan and M of the turbulence-chemistry interaction (TCI) are performed in hypersonic tur- bulent boundary layers using direct numerical simulation (DNS) flow fields under typical hypersonic conditions representative of blunt

  11. Heat release effects on decaying homogeneous compressible turbulence

    E-Print Network [OSTI]

    Lee, Kurn Chul

    2009-05-15T23:59:59.000Z

    turbulence. A good understanding of high-enthalpy compressible turbulence is crucial for analyzing the flow around re-entry spacecrafts and hypersonic flight vehicles, and inside scramjet engines. One main factor affecting turbulence in these high...

  12. Experimental investigation of over-expanded supersonic steam jet submerged in quiescent water

    SciTech Connect (OSTI)

    Wu, Xin-Zhuang; Yan, Jun-Jie; Li, Wen-Jun; Pan, Dong-Dong; Liu, Guang-Yao [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China)

    2010-01-15T23:59:59.000Z

    This study was designed to determine the behaviour of an over-expanded supersonic steam jet in quiescent water. Only two shapes of steam plume were observed and an analytical model was constructed. The axial and radial temperature distributions were measured in the steam plume and in the surrounding water. The flow pattern and temperature distributions were influenced mainly by steam mass flux and water temperature. The results confirmed the occurrence of compression and expansion waves in the steam plume, and indicated that the temperature distributions reflected the steam plume shapes. The axial temperature distributions in the forepart of the steam plume were independent of water temperature. Empirical correlations were found that predicted the dimensionless axial and radial temperatures of the turbulent jet region. Moreover, prediction of the steam plume length by the dimensionless axial temperature showed good agreement with the experimental results. (author)

  13. Monte Carlo Tools for Jet Quenching

    E-Print Network [OSTI]

    Korinna Zapp

    2011-09-07T23:59:59.000Z

    A thorough understanding of jet quenching on the basis of multi-particle final states and jet observables requires new theoretical tools. This talk summarises the status and propects of the theoretical description of jet quenching in terms of Monte Carlo generators.

  14. Photoproduction of jets at NLO

    E-Print Network [OSTI]

    B. W. Harris; J. F. Owens

    1996-08-20T23:59:59.000Z

    A new next-to-leading order Monte Carlo program for the calculation of fully differential jet cross sections in photoproduction is described. The contributions from both resolved and direct components are included. A comparison between the theoretical predictions and ZEUS data is presented.

  15. The Disc-Jet Connection

    E-Print Network [OSTI]

    Ralph E. Pudritz; Robi Banerjee

    2005-07-11T23:59:59.000Z

    A large body of theoretical and computational work shows that jets - modelled as magnetized disk winds - exert an external torque on their underlying disks that can efficiently remove angular momentum and act as major drivers of disk accretion. These predictions have recently been confirmed in direct HST measurements of the jet rotation and angular momentum transport in low mass protostellar systems. We review the theory of disc winds and show that their physics is universal and scales to jets from both low and high mass star forming regions. This explains the observed properties of outflows in massive star forming regions, before the central massive star generates an ultracompact HII region. We also discuss the recent numerical studies on the formation of massive accretion disks and outflows through gravitational collapse, including our own work on 3D Adaptive Mesh simulations (using the FLASH code) of the hydromagnetic collapse of an initial rotating, and cooling Bonner-Ebert sphere. Magnetized collapse gives rise to outflows. Our own simulations show that both a jet-like disk wind on sub AU scales, and a larger scale molecular outflow occur (Banerjee and Pudritz 2005).

  16. Laser Created Relativistic Positron Jets

    SciTech Connect (OSTI)

    Chen, H; Wilks, S C; Meyerhofer, D D; Bonlie, J; Chen, C D; Chen, S N; Courtois, C; Elberson, L; Gregori, G; Kruer, W; Landoas, O; Mithen, J; Murphy, C; Nilson, P; Price, D; Scheider, M; Shepherd, R; Stoeckl, C; Tabak, M; Tommasini, R; Beiersdorder, P

    2009-10-08T23:59:59.000Z

    Electron-positron jets with MeV temperature are thought to be present in a wide variety of astrophysical phenomena such as active galaxies, quasars, gamma ray bursts and black holes. They have now been created in the laboratory in a controlled fashion by irradiating a gold target with an intense picosecond duration laser pulse. About 10{sup 11} MeV positrons are emitted from the rear surface of the target in a 15 to 22-degree cone for a duration comparable to the laser pulse. These positron jets are quasi-monoenergetic (E/{delta}E {approx} 5) with peak energies controllable from 3-19 MeV. They have temperatures from 1-4 MeV in the beam frame in both the longitudinal and transverse directions. Positron production has been studied extensively in recent decades at low energies (sub-MeV) in areas related to surface science, positron emission tomography, basic antimatter science such as antihydrogen experiments, Bose-Einstein condensed positronium, and basic plasma physics. However, the experimental tools to produce very high temperature positrons and high-flux positron jets needed to simulate astrophysical positron conditions have so far been absent. The MeV temperature jets of positrons and electrons produced in our experiments offer a first step to evaluate the physics models used to explain some of the most energetic phenomena in the universe.

  17. Turbulent electron transport in edge pedestal by electron temperature gradient turbulence

    SciTech Connect (OSTI)

    Singh, R. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Jhang, Hogun [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)] [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Diamond, P. H. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); CMTFO and CASS, University of California, San Diego 92093-0424, California (United States)

    2013-11-15T23:59:59.000Z

    We present a model for turbulent electron thermal transport at the edge pedestal in high (H)-mode plasmas based on electron temperature gradient (ETG) turbulence. A quasi-linear analysis of electrostatic toroidal ETG modes shows that both turbulent electron thermal diffusivity and hyper-resistivity exhibits the Ohkawa scaling in which the radial correlation length of turbulence becomes the order of electron skin depth. Combination of the Ohkawa scales and the plasma current dependence results in a novel confinement scaling inside the pedestal region. It is also shown that ETG turbulence induces a thermoelectric pinch, which may accelerate the density pedestal formation.

  18. Jet energy scale setting with "photon+Jet" events at LHC energies. Selection of events with a clean "photon+Jet" topology and photon Pt - jet Pt disbalance

    E-Print Network [OSTI]

    D. V. Bandourin; V. F. Konoplyanikov; N. B. Skachkov

    2001-04-27T23:59:59.000Z

    It is shown in the paper that Pt activity limitation (modulus of the vector sum) of all particle beyond "photon+Jet" system Pt^out leads to the noticeable photon Pt - jet Pt disbalance decreasing. On a simultaneous restriction of the cluster Pt and Pt^out from above it is possible to reach an acceptable balance between photon Pt - jet Pt with a sufficient number of the photon Pt - jet Pt events for the jet energy scale setting and hadron calorimeter calibratiom of the CMS detector at LHC.

  19. Turbulent transport of energetic ions

    SciTech Connect (OSTI)

    Dannert, Tilman; Hauff, Thilo; Jenko, Frank; Guenter, Sibylle [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    2006-11-30T23:59:59.000Z

    Approaching ITER operation, the issue of anomalous transport of fast particles becomes more and more important. This is partly because the ITER heating and current drive system relies heavily on neutral beam injection. Moreover burning plasmas are heated by fast fusion {alpha} particles.Fusion {alpha} particles are characterised by a fixed energy and an isotropic velocity distribution. Therefore they have gyroradii one magnitude larger than the thermal ions. The dependency of the particle diffusion of {alpha} test particles on the Kubo number K = VExB{tau}c/{lambda}c (VExB mean E x B velocity, {tau}c, {lambda}c correlation time and length of the turbulent potential) is presented. For different turbulent regimes, different dependency of the diffusion on the gyroradius is found. For large Kubo numbers, the transport is found to remain constant for gyroradii up to the correlation length of the potential, whereas it is drastically reduced in the small Kubo number regime.In the second part, a model for beam ions injected along the equilibrium magnetic field is described. The beam ions are treated gyrokinetically in a self-consistent way with the equilibrium distribution function taken as a shifted Maxwellian. The implications of such a model for the Vlasov equation, the field equations, and the calculation of moments and fluxes are discussed. Linear and nonlinear results, obtained with the gyrokinetic flux tube code GENE show the existence of a new instability driven by fast beam ions. The instability has a maximum growth rate at perpendicular wave numbers of ky{rho}s {approx} 0.15 and depends mainly on the beam velocity and the density gradient of the beam ions. This instability leads to a replacement of bulk ion particle transport by fast ion particle transport, connected to a strongly enhanced heat flux. In the presence of this instability, the turbulent particle and heat transport is dominated by fast ions.

  20. Stochastic models for turbulent reacting flows

    SciTech Connect (OSTI)

    Kerstein, A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01T23:59:59.000Z

    The goal of this program is to develop and apply stochastic models of various processes occurring within turbulent reacting flows in order to identify the fundamental mechanisms governing these flows, to support experimental studies of these flows, and to further the development of comprehensive turbulent reacting flow models.

  1. AIAA-92-5101 Hypersonic Turbulent

    E-Print Network [OSTI]

    Texas at Arlington, University of

    AIAA-92-5101 Hypersonic Turbulent Expansion-Corner Flow with Impingement K. Chung & F. Lu;HYPERSONIC TURBULENT EXPANSION-CORNER FLOW WITH SHOCK IMPINGEMENT ICung-Ming Chung* and Frank IC. Lut of considcrablc research.' Recently, renewed in- tcrcst in supersonic and hypersonic flight vehicles has

  2. Electric field statistics in MHD turbulence

    E-Print Network [OSTI]

    Low, Robert

    Electric field statistics in MHD turbulence Bernard Knaepen, Nicolas Denewet & Daniele Carati, ULB #12;Electric field statistics in MHD turbulence Outline Electric field in MHD? Particle acceleration Statistics of the electric & magnetic fields #12;Outline Electric field in MHD? Particle acceleration

  3. Cyclone separator having boundary layer turbulence control

    DOE Patents [OSTI]

    Krishna, Coimbatore R. (Mt. Sinai, NY); Milau, Julius S. (Port Jefferson, NY)

    1985-01-01T23:59:59.000Z

    A cyclone separator including boundary layer turbulence control that is operable to prevent undue build-up of particulate material at selected critical areas on the separator walls, by selectively varying the fluid pressure at those areas to maintain the momentum of the vortex, thereby preventing particulate material from inducing turbulence in the boundary layer of the vortical fluid flow through the separator.

  4. Fifteen Lectures on Laminar and Turbulent Combustion

    E-Print Network [OSTI]

    Peters, Norbert

    Fifteen Lectures on Laminar and Turbulent Combustion N. Peters RWTH Aachen Ercoftac Summer School in Combustion Systems 1 Lecture 2: Calculation of Adiabatic Flame Temperatures and Chemical Equilibria 20: Laminar Diffusion Flames: Different Flow Geometries 156 Lecture 11: Turbulent Combustion: Introduction

  5. Synthetic jets at large Reynolds number and comparison to continuous jets

    SciTech Connect (OSTI)

    Smith, B. L. (Barton L.); Swift, G. W. (Gregory W.)

    2001-01-01T23:59:59.000Z

    Experimental measurements and flow visualization of synthetic jets and similar continuous jets are described. The dimensionless stroke length necessary to form a 2-D synthetic jet is between 5 and 10, with wider-nozzle jets consistently requiring a smaller value. Synthetic jets are wider, slower and have more momentum than similar continuous jets. Synthetic jets are generated using four nozzle widths that vary by a factor of four, and the driving frequency is varied over an order of magnitude. The resultant jets are in the range 13.5 < L{sub o}/h < 80.8 and 695 < Re{sub Uo} < 14700. In spite of the large range of stroke lengths, the near-field behavior of the synthetic jets scales with L{sub o}/h.

  6. Scaling Laws for Reduced-Scale Tests of Pulse Jet Mixing Systems in Non-Newtonian Slurries: Mixing Cavern Behavior

    SciTech Connect (OSTI)

    Meyer, Perry A.; Kurath, Dean E.; Bamberger, Judith A.; Barnes, Steven M.; Etchells, Arthur W.

    2006-03-02T23:59:59.000Z

    The Waste Treatment Plant (WTP) under construction at the Hanford Site will use pulse jet mixer (PJM) technology for mixing and gas retention control applications in tanks expected to contain waste slurries exhibiting a non-Newtonian rheology. This paper presents the results of theoretical and experimental studies undertaken to establish a methodology to perform reduced-scale mixing tests with PJM systems in non-Newtonian fluids. A theoretical model for mixing cavern formation from steady and pulsed jets is developed and compared with data from a single unsteady jet in a yield stress simulant. Dimensional analysis is used to identify the important dimensionless parameters affecting mixing performance in more complex systems. Scaling laws are proposed based on the modeling and dimensional analysis. Experimental validation of the scaling laws governing unsteady jet mixing in non-Newtonian fluids are also presented. Tests were conducted at three scales using two non-Newtonian simulants. The data were compared non-dimensionally, and the important scale laws were confirmed. The key dimensionless parameters were found to be the Strouhal number (which describes unsteady pulse jet mixer operation), the yield Reynolds number (which governs cavern formation due to non-Newtonian fluid behavior), and the viscous Reynolds number (which determines the flow regime and the degree of turbulence). The experimentally validated scaling laws provide the basis for reduced scale testing of prototypic WTP mixing systems. It is argued that mixing systems developed from reduced scale testing will produce conservative designs at full scale.

  7. On the Asymptotic Behaviour of Circular Fuzzy Cellular Automata

    E-Print Network [OSTI]

    Flocchini, Paola

    fuzzification) . Fuzzy cellular automata were first introduced in [5] as a model to describe the impact CA (e.g., see [11]). They have been shown to be useful tools for pattern recognition purposes (eOn the Asymptotic Behaviour of Circular Fuzzy Cellular Automata HEATHER BETEL AND PAOLA FLOCCHINI

  8. How to project `circular' manifolds using geodesic distances?

    E-Print Network [OSTI]

    Verleysen, Michel

    How to project `circular' manifolds using geodesic distances? John Aldo Lee, Michel Verleysen,verleysen}@dice.ucl.ac.be Abstract. Recent papers have clearly shown the advantage of using the geodesic distance instead strongly crumpled manifolds have to be un- folded. Nevertheless, neither the Euclidean nor the geodesic

  9. Using Circular Programs to Deforest in Accumulating Parameters

    E-Print Network [OSTI]

    Eckmiller, Rolf

    Using Circular Programs to Deforest in Accumulating Parameters Janis Voigtl Ë? ander # Department classical deforestation techniques fail. In order to avoid multiple traversals of the input data structure, deforestation, intermediate data structures, lazy composition, lazy evalu­ ation, multiple traversals, program

  10. Drought Strategies for Alfalfa Cooperative Extension Service Circular 581

    E-Print Network [OSTI]

    Mukhtar, Saqib

    Drought Strategies for Alfalfa Cooperative Extension Service · Circular 581 College of Agriculture and Home Economics #12;1 Drought Strategies for Alfalfa With continued dry conditions throughout New Mexico, farmers with alfalfa fields should consider sev- eral production strategies in order to preserve alfalfa

  11. "Circularization" vs. Accretion -- What Powers Tidal Disruption Events?

    E-Print Network [OSTI]

    Piran, Tsvi; Krolik, Julian; Cheng, Roseanne M; Shiokawa, Hotaka

    2015-01-01T23:59:59.000Z

    A tidal disruption event (TDE) takes place when a star passes near enough to a massive black hole to be disrupted. About half the star's matter is given elliptical trajectories with large apocenter distances, the other half is unbound. To "circularize", i.e., to form an accretion flow, the bound matter must lose a significant amount of energy, with the actual amount depending on the characteristic scale of the flow measured in units of the black hole's gravitational radius (~ 10^{51} (R/1000R_g)^{-1} erg). Recent numerical simulations (Shiokawa et al., 2015) have revealed that the circularization scale is close to the scale of the most-bound initial orbits, ~ 10^3 M_{BH,6.5}^{-2/3} R_g ~ 10^{15} M_{BH,6.5}^{1/3} cm from the black hole, and the corresponding circularization energy dissipation rate is $\\sim 10^{44} M_{BH,6.5}^{-1/6}$~erg/s. We suggest that the energy liberated during circularization, rather then energy liberated by accretion onto the black hole, powers the observed optical TDE candidates (e.g.A...

  12. Great Plains Turbulence Environment: Its Origins, Impact, and Simulation

    SciTech Connect (OSTI)

    Kelley, N. D.; Jonkman, B. J.; Scott, G. N.

    2006-12-01T23:59:59.000Z

    This paper summarizes the known impacts of nocturnal turbulence on wind turbine performance and operations.

  13. Numerical Simulations of Bouncing Jets

    E-Print Network [OSTI]

    Lee, Sanghyun

    2014-07-18T23:59:59.000Z

    downhill gliding of the pool, at about 4mm/s of pool surface velocity. . . . . . . . . . . . . . . . . . . . . . 87 viii 5.7 Overall view of the shampoo jet bouncing of an inclined pool of the same liquid. The white arrow points at he breakup of the air....4 Time discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.5 Entropy residual stabilization . . . . . . . . . . . . . . . . . . . . . . 58 3.6 Adaptive mesh refinement . . . . . . . . . . . . . . . . . . . . . . . . 61 iv 3.7...

  14. Fluid jet electric discharge source

    DOE Patents [OSTI]

    Bender, Howard A. (Ripon, CA)

    2006-04-25T23:59:59.000Z

    A fluid jet or filament source and a pair of coaxial high voltage electrodes, in combination, comprise an electrical discharge system to produce radiation and, in particular, EUV radiation. The fluid jet source is composed of at least two serially connected reservoirs, a first reservoir into which a fluid, that can be either a liquid or a gas, can be fed at some pressure higher than atmospheric and a second reservoir maintained at a lower pressure than the first. The fluid is allowed to expand through an aperture into a high vacuum region between a pair of coaxial electrodes. This second expansion produces a narrow well-directed fluid jet whose size is dependent on the size and configuration of the apertures and the pressure used in the reservoir. At some time during the flow of the fluid filament, a high voltage pulse is applied to the electrodes to excite the fluid to form a plasma which provides the desired radiation; the wavelength of the radiation being determined by the composition of the fluid.

  15. Turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2TopoPortalBRDFTunable ThermalTurbines

  16. Blind source separation of convolutive mixtures of non circular linearly modulated signals with unknown baud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Blind source separation of convolutive mixtures of non circular linearly modulated signals addresses the problem of blind separation of convolutive mix- tures of BPSK and circular linearly modulated theoretical statements. Keywords: Blind source separation, Convolutive mixture, Constant Modulus Algorithm

  17. Combining Resummed Higgs Predictions Across Jet Bins

    E-Print Network [OSTI]

    Radja Boughezal; Xiaohui Liu; Frank Petriello; Frank J. Tackmann; Jonathan R. Walsh

    2013-12-16T23:59:59.000Z

    Experimental analyses often use jet binning to distinguish between different kinematic regimes and separate contributions from background processes. To accurately model theoretical uncertainties in these measurements, a consistent description of the jet bins is required. We present a complete framework for the combination of resummed results for production processes in different exclusive jet bins, focusing on Higgs production in gluon fusion as an example. We extend the resummation of the Higgs + 1-jet cross section into the challenging low transverse momentum region, lowering the uncertainties considerably. We provide combined predictions with resummation for cross sections in the Higgs + 0-jet and Higgs + 1-jet bins, and give an improved theory covariance matrix for use in experimental studies. We estimate that the relevant theoretical uncertainties on the signal strength in the Higgs to WW analysis are reduced by nearly a factor of 2 compared to the current value.

  18. Free Energy Cascade in Gyrokinetic Turbulence

    SciTech Connect (OSTI)

    Banon Navarro, A.; Morel, P.; Albrecht-Marc, M.; Carati, D. [Universite Libre de Bruxelles, Faculte des Sciences, Physique Statistique et Plasmas CP 231, EURATOM Association, Campus Plaine, 1050 Brussels (Belgium); Merz, F.; Goerler, T.; Jenko, F. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)

    2011-02-04T23:59:59.000Z

    In gyrokinetic theory, the quadratic nonlinearity is known to play an important role in the dynamics by redistributing (in a conservative fashion) the free energy between the various active scales. In the present study, the free energy transfer is analyzed for the case of ion temperature gradient driven turbulence. It is shown that it shares many properties with the energy transfer in fluid turbulence. In particular, one finds a (strongly) local, forward (from large to small scales) cascade of free energy in the plane perpendicular to the background magnetic field. These findings shed light on some fundamental properties of plasma turbulence, and encourage the development of large-eddy-simulation techniques for gyrokinetics.

  19. LDV Measurement of Confined Parallel Jet Mixing

    SciTech Connect (OSTI)

    R.F. Kunz; S.W. D'Amico; P.F. Vassallo; M.A. Zaccaria

    2001-01-31T23:59:59.000Z

    Laser Doppler Velocimetry (LDV) measurements were taken in a confinement, bounded by two parallel walls, into which issues a row of parallel jets. Two-component measurements were taken of two mean velocity components and three Reynolds stress components. As observed in isolated three dimensional wall bounded jets, the transverse diffusion of the jets is quite large. The data indicate that this rapid mixing process is due to strong secondary flows, transport of large inlet intensities and Reynolds stress anisotropy effects.

  20. Jet physics in Run 2 at CDF

    SciTech Connect (OSTI)

    Field, R.; /Florida U.

    2005-01-01T23:59:59.000Z

    New CDF Run 2 results on the inclusive jet cross section (K{sub T} algorithm) and the b-jet cross section (MidPoint algorithm) are presented and compared with theory. We also study the ''underlying event'' by using the direction of the leading jet to isolate regions of {eta}-{phi} space that are very sensitive to the ''beam-beam'' remnants and to multiple parton interactions.

  1. Coshcous turbulence and its thermalization

    SciTech Connect (OSTI)

    Zhu, Jian-zhou [Los Alamos National Laboratory; Taylor, Mark [SNL

    2008-01-01T23:59:59.000Z

    Dissipation rate {mu}[cosh(k/k{sub c}) - 1] in Fourier space, which reduces to the Newtonian viscosity dissipation rate {nu}k{sup 2} for small k/k{sub c}, can be scaled to make a hydrodynamic system either actually or potentially converge to its Galerkin truncation. The former case acquires convergence to the truncation at a finite wavenumber k{sub G}; the latter realizes as the wavenumber grows to infinity. Intermittency reduction and vitiation of extended self-similarity (ESS) in the partially thermalized regime of turbulence are confirmed and clarified. Onsager's pictures of intermittent versus nonintermittent flows are visualized from thermalized numerical fields, showing cleanly spotty versus mistily uniform properties, the latter of which destroys self-organization and so the ESS property.

  2. Nuclear Composition of Magnetized GRB Jets

    E-Print Network [OSTI]

    Shibata, Sanshiro

    2015-01-01T23:59:59.000Z

    We investigate the fraction of metal nuclei in the relativistic jets of gamma-ray bursts associated with core-collapse supernovae. We simulate the fallback in jet-induced explosions with two-dimensional relativistic hydrodynamics calculations and the jet acceleration with steady, radial, relativistic magnetohydrodynamics calculations, and derive detail nuclear composition of the jet by postprocessing calculation. We found that if the temperature at the jet launch site is above $4.7\\times 10^9$K, quasi-statistical equilibrium (QSE) is established and heavy nuclei are dissociated to light particles such as $^4$He during the acceleration of the jets. The criterion for the survival of metal nuclei is written in terms of the isotropic jet luminosity as $L_{\\rm j}^{\\rm iso} \\lesssim 3.9\\times 10^{50}(R_{\\rm i}/10^7{\\rm cm})^2 (1+\\sigma_{\\rm i})~{\\rm erg~s^{-1}}$, where $R_{\\rm i}$ and $\\sigma_{\\rm i}$ are the initial radius of the jets and the initial magnetization parameter, respectively. If the jet is initially d...

  3. PHYSICAL PARAMETERS OF STANDARD AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Pucci, Stefano; Romoli, Marco [Department of Physics and Astronomy, University of Firenze, I-50121 Firenze (Italy); Poletto, Giannina [INAF-Arcetri Astrophysical Observatory, I-50125 Firenze (Italy); Sterling, Alphonse C., E-mail: stpucci@arcetri.astro.it [Space Science Office, NASA/MSFC, Huntsville, Al 35812 (United States)

    2013-10-10T23:59:59.000Z

    The X-ray Telescope on board the Hinode mission revealed the occurrence, in polar coronal holes, of much more numerous jets than previously indicated by the Yohkoh/Soft X-ray Telescope. These plasma ejections can be of two types, depending on whether they fit the standard reconnection scenario for coronal jets or if they include a blowout-like eruption. In this work, we analyze two jets, one standard and one blowout, that have been observed by the Hinode and STEREO experiments. We aim to infer differences in the physical parameters that correspond to the different morphologies of the events. To this end, we adopt spectroscopic techniques and determine the profiles of the plasma temperature, density, and outflow speed versus time and position along the jets. The blowout jet has a higher outflow speed, a marginally higher temperature, and is rooted in a stronger magnetic field region than the standard event. Our data provide evidence for recursively occurring reconnection episodes within both the standard and the blowout jet, pointing either to bursty reconnection or to reconnection occurring at different locations over the jet lifetimes. We make a crude estimate of the energy budget of the two jets and show how energy is partitioned among different forms. Also, we show that the magnetic energy that feeds the blowout jet is a factor of 10 higher than the magnetic energy that fuels the standard event.

  4. Drying characteristics of slot jet reattachment nozzle and comparison with a slot jet nozzle

    E-Print Network [OSTI]

    Alam, Syed Aftab

    2012-06-07T23:59:59.000Z

    the same flow power and flow exerted surface peak pressure. The same flow power results showed that +45[] and +20[] SJR nozzles performed better than the slot jet nozzle, while the 0[] SJR had drying characteristics similar to the slot jet. The slot jet...

  5. NuSTAR SPECTROSCOPY OF GRS 1915+105: DISK REFLECTION, SPIN, AND CONNECTIONS TO JETS

    SciTech Connect (OSTI)

    Miller, J. M.; King, A. L. [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1046 (United States)] [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1046 (United States); Parker, M. L.; Fabian, A. C. [Institute of Astronomy, The University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom)] [Institute of Astronomy, The University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Fuerst, F.; Walton, D. J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125 (United States)] [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125 (United States); Bachetti, M.; Harrison, F. A.; Barret, D.; Grefenstette, B. W. [Universite de Toulouse, UPS-OMP, F-31400 Toulouse (France)] [Universite de Toulouse, UPS-OMP, F-31400 Toulouse (France); Boggs, S. E.; Tomsick, J. A. [Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States)] [Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Chakrabarty, D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States)] [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States); Christensen, F. E. [Danish Technical University, DK-2800 Lyngby (Denmark)] [Danish Technical University, DK-2800 Lyngby (Denmark); Craig, W. W. [Lawrence Livermore National Laboratory, Livermore, CA (United States)] [Lawrence Livermore National Laboratory, Livermore, CA (United States); Hailey, C. J. [Columbia University, New York, NY 10027 (United States)] [Columbia University, New York, NY 10027 (United States); Stern, D. K. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)] [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Zhang, W. W., E-mail: jonmm@umich.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-10-01T23:59:59.000Z

    We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a 'plateau' state. This state is of special interest because it is similar to the 'low/hard' state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 ± 0.01 (1? statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.

  6. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect (OSTI)

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H. [Laboratoire de Mécanique des Fluides et d’Acoustique, CNRS/Université de Lyon, Ecole Centrale de Lyon/Université Lyon 1/INSA de Lyon, ECL, 36 Avenue Guy de Collongue, 69134 Ecully Cedex (France); Garandet, J.-P. [CEA, Laboratoire d’Instrumentation et d’Expérimentation en Mécanique des Fluides et Thermohydraulique, DEN/DANS/DM2S/STMF/LIEFT, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France)

    2014-09-15T23:59:59.000Z

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  7. TIDAL TURBULENCE SPECTRA FROM A COMPLIANT MOORING

    SciTech Connect (OSTI)

    Thomson, Jim; Kilcher, Levi; Richmond, Marshall C.; Talbert, Joe; deKlerk, Alex; Polagye, Brian; Guerra, Maricarmen; Cienfuegos, Rodrigo

    2013-06-13T23:59:59.000Z

    A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demon- stration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspend- ing Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion cor- rection (post-processing), data quality is further improved; the relative merits of direct and spectral motion correction are dis- cussed.

  8. Turbulent diffusion with rotation or magnetic fields

    E-Print Network [OSTI]

    Brandenburg, Axel; Vasil, Geoffrey M

    2009-01-01T23:59:59.000Z

    The turbulent diffusion tensor describing the evolution of the mean concentration of a passive scalar is investigated for forced turbulence either in the presence of rotation or a magnetic field. With rotation the Coriolis force causes a sideways deflection of the flux of mean concentration. Within the magnetohydrodynamics approximation there is no analogous effect from the magnetic field because the effects on the flow do not depend on the sign of the field. Both rotation and magnetic fields tend to suppress turbulent transport, but this suppression is weaker in the direction along the magnetic field. Turbulent transport along the rotation axis is not strongly affected by rotation, except on shorter length scales, i.e. when the scale of the variation of the mean field becomes comparable with the scale of the energy-carrying eddied.

  9. Inhomogeneous distribution of droplets in cloud turbulence

    E-Print Network [OSTI]

    Itzhak Fouxon; Yongnam Park; Roei Harduf; Changhoon Lee

    2014-10-30T23:59:59.000Z

    We solve the problem of spatial distribution of inertial particles that sediment in turbulent flow with small ratio of acceleration of fluid particles to acceleration of gravity $g$. The particles are driven by linear drag and have arbitrary inertia. The pair-correlation function of concentration obeys a power-law in distance with negative exponent. Divergence at zero signifies singular distribution of particles in space. Independently of particle size the exponent is ratio of integral of energy spectrum of turbulence times the wavenumber to $g$ times numerical factor. We find Lyapunov exponents and confirm predictions by direct numerical simulations of Navier-Stokes turbulence. The predictions include typical case of water droplets in clouds. This significant progress in the study of turbulent transport is possible because strong gravity makes the particle's velocity at a given point unique.

  10. Turbulence in Astrophysical and Laboratory Plasmas

    E-Print Network [OSTI]

    Shyy, Wei

    MIPSE, Univ of Michigan September 15, 2010 #12;Contributing Colleagues Steve Cowley (UKAEA & Imperial-principles modeling · Identification of Alfvenic solar wind turbulence · Conclusion #12;Kinetic theory when (or ) f

  11. Aspects of Wave Turbulence in Preheating

    E-Print Network [OSTI]

    José A. Crespo; H. P. de Oliveira

    2014-06-04T23:59:59.000Z

    In this work we have studied the nonlinear preheating dynamics of the $\\frac{1}{4} \\lambda \\phi^4$ inflationary model. It is well established that after a linear stage of preheating characterized by the parametric resonance, the nonlinear dynamics becomes relevant driving the system towards turbulence. Wave turbulence is the appropriated description of this phase since matter distributions are fields instead of usual fluids. Therefore, turbulence develops due to the nonlinear interations of waves, here represented by the small inhomogeneities of the inflaton field. We present relevant aspects of wave turbulence such as the Kolmogorov-Zakharov spectrum in frequency and wave number domains that indicates that there are a transfer of energy through scales. From the power spectrum of the matter energy density we were able to estimate the temperature of the thermalized system.

  12. Bayesian calibration of a k -turbulence model for predictive jet-in-crossflow simulations

    E-Print Network [OSTI]

    Ray, Jaideep

    -in-crossflow (JIC) is a canonical flow problem of fuel-air mixing in scramjet engines.1 It is also relevant

  13. Particle dispersion within zonal jets in two-layer beta-plane turbulence

    E-Print Network [OSTI]

    Roman, Jennifer Claire

    1996-01-01T23:59:59.000Z

    . were a, passive tracer. In eitlier case, liigh p. v. air from inside the polar vortex ivas ejected into lower latitudes, and thc vort&ix was eroded. Polvani and Plumb (1992) further classifie ivave-breaking using the Contour Dynamics method on a... decreases), a, parameter ivas needed that. allowed for relative comparisons of timescales in the two simulations. Thus, an Eulerian timescale was developed by examining thc cd&ly kinetic energies of the two cases. The eddy kinetic energy of a flow...

  14. Phenomenology of turbulent dynamo growth and saturation

    E-Print Network [OSTI]

    Rodion Stepanov; Franck Plunian

    2007-11-08T23:59:59.000Z

    With a non local shell model of magnetohydrodynamic turbulence we investigate numerically the turbulent dynamo action for low and high magnetic Prandtl numbers ($Pm$). The results obtained in the kinematic regime and along the way to dynamo saturation are understood in terms of a phenomenological approach based on the local ($Pm\\ll 1$) or non local ($Pm\\gg 1$) nature of the energy transfers. In both cases the magnetic energy grows at small scale and saturates as an inverse `` cascade ''.

  15. Circular polarization of obliquely propagating whistler wave magnetic field

    SciTech Connect (OSTI)

    Bellan, P. M. [Applied Physics, Caltech, Pasadena California 91125 (United States)] [Applied Physics, Caltech, Pasadena California 91125 (United States)

    2013-08-15T23:59:59.000Z

    The circular polarization of the magnetic field of obliquely propagating whistler waves is derived using a basis set associated with the wave partial differential equation. The wave energy is mainly magnetic and the wave propagation consists of this magnetic energy sloshing back and forth between two orthogonal components of magnetic field in quadrature. The wave electric field energy is small compared to the magnetic field energy.

  16. Circular hydraulic jump in generalized-Newtonian fluids

    E-Print Network [OSTI]

    Rai, Ashutosh; Poria, Swarup

    2008-01-01T23:59:59.000Z

    We carry out an analytical study of laminar circular hydraulic jumps, in generalized-Newtonian fluids obeying the two-parametric power-law model of Ostwald-de Waele. Under the boundary-layer approximation we obtained exact expressions determining the flow, an implicit relation for the jump radius is derived. Corresponding results for Newtonian fluids can be retrieved as a limiting case for the flow behavior index n=1, predictions are made for fluids deviating from Newtonian behavior.

  17. Friction (Chapter 5, section 8) & Circular Motion (Chapter 6,

    E-Print Network [OSTI]

    1 Week 5 Friction (Chapter 5, section 8) & Circular Motion (Chapter 6, sections 1-2) Lecture Quiz 1 travels in time t is: A. x B. 1.5x C. 3x D. 4.5x E. 9x Forces of Friction When an object to the interactions between the object and its environment This resistance is called the force of friction Forces

  18. Gravitational field of a stationary circular cosmic string loop

    E-Print Network [OSTI]

    A; A. Sen; N. Banerjee

    1998-06-22T23:59:59.000Z

    Gravitational field of a stationary circular cosmic string loop has been studied in the context of full nonlinear Einstein's theory of gravity. It has been assumed that the radial and tangential stresses of the loop are equal to the energy density of the string loop. An exact solution for the system has been presented which has a singularity at a finite distance from the axis,but is regular for any other distances from the axis of the loop.

  19. Circular modes for flat beams in the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Burov, A.

    2013-06-01T23:59:59.000Z

    Typically x/y optical coupling is considered as unwanted and thus suppressed; particular exclusions are electron and ionization coolers. Could some special coupled modes be effectively applied for the LHC complex? Perhaps, the answer is positive: use of the circular modes in the injectors with their transformation into planar modes in the LHC allows both the space charge and beam-beam luminosity limitations to be significantly reduced, if not practically eliminated.

  20. Polarization of Astronomical Maser Radiation. IV. Circular Polarization Profiles

    E-Print Network [OSTI]

    Moshe Elitzur

    1998-04-03T23:59:59.000Z

    Profile comparison of the Stokes parameters $V$ and $I$ is a powerful tool for maser data analysis, providing the first direct methods for unambiguous determination of (1) the maser saturation stage, (2) the amplification optical depth and intrinsic Doppler width of unsaturated masers, and (3) the comparative magnitudes of Zeeman splitting and Doppler linewidth. Circular polarization recently detected in OH 1720 MHz emission from the Galactic center appears to provide the first direct evidence for maser saturation.

  1. PRIMER CONGRS NACIONAL 2 Circular (pre-programa)

    E-Print Network [OSTI]

    Escolano, Francisco

    PRIMER CONGR�S NACIONAL 2ª Circular (pre-programa) EL PAISATGE DELS RIURAUS: ARQUITECTURA, HER�NCIA dels riuraus: arquitectura, herència i reptes. Tot partint d'aquestes premisses el congrés pretén rebre a quatre grans àmbits: 1. ETNOGR�FIC-HIST�RIC 2. ARQUITECTURA I PAISATGE RURAL 3. TURÍSTIC I TERRITORIAL 4

  2. Relativistic high harmonic generation in gas jet targets

    SciTech Connect (OSTI)

    Pirozhkov, A.S.; Kando, M.; Esirkepov, T.Zh.; and others

    2012-07-11T23:59:59.000Z

    We experimentally demonstrate a new regime of high-order harmonic generation by relativistic-irradiance lasers in gas jet targets. Bright harmonics with both odd and even orders, generated by linearly as well as circularly polarized pulses, are emitted in the forward direction, while the base harmonic frequency is downshifted. A 9 TW laser generates harmonics up to 360 eV, within the 'water window' spectral region. With a 120 TW laser producing 40 uJ/sr per harmonic at 120 eV, we demonstrate the photon number scalability. The observed harmonics cannot be explained by previously suggested scenarios. A novel high-order harmonics generation mechanism [T. Zh. Esirkepov et al., AIP Proceedings, this volume], which explains our experimental findings, is based on the phenomena inherent in the relativistic laser - underdense plasma interactions (self-focusing, cavity evacuation, and bow wave generation), mathematical catastrophe theory which explains formation of electron density singularities (cusps), and collective radiation due to nonlinear oscillations of a compact charge.

  3. Reaction and diffusion in turbulent combustion

    SciTech Connect (OSTI)

    Pope, S.B. [Mechanical and Aerospace Engineering, Ithaca, NY (United States)

    1993-12-01T23:59:59.000Z

    The motivation for this project is the need to obtain a better quantitative understanding of the technologically-important phenomenon of turbulent combustion. In nearly all applications in which fuel is burned-for example, fossil-fuel power plants, furnaces, gas-turbines and internal-combustion engines-the combustion takes place in a turbulent flow. Designers continually demand more quantitative information about this phenomenon-in the form of turbulent combustion models-so that they can design equipment with increased efficiency and decreased environmental impact. For some time the PI has been developing a class of turbulent combustion models known as PDF methods. These methods have the important virtue that both convection and reaction can be treated without turbulence-modelling assumptions. However, a mixing model is required to account for the effects of molecular diffusion. Currently, the available mixing models are known to have some significant defects. The major motivation of the project is to seek a better understanding of molecular diffusion in turbulent reactive flows, and hence to develop a better mixing model.

  4. Space variations in axis height of the jet stream core

    E-Print Network [OSTI]

    Leutwyler, Cooke Hearon

    1965-01-01T23:59:59.000Z

    height of the jet axis relative to the height of the jet maximum for slow vs. fast cases. 13 Mean height of the jet axis relative to the height at the trough. 13 Mean height of the jet axis relative to the height at the ridge. 15 Mean height... of the jet axis relative to the height at the jet maximum, when the maximum is near a trough. 15 Mean height of the jet axis relative to the height at the minimum, when the minimum is near a ridge. 17 Mean height of the jet axis relative to the height...

  5. Electrical studies and plasma characterization of an atmospheric pressure plasma jet operated at low frequency

    SciTech Connect (OSTI)

    Giuliani, L.; Xaubet, M.; Grondona, D.; Minotti, F.; Kelly, H. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina and Instituto de Física del Plasma (INFIP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires UBA, C1428EHA Buenos Aires (Argentina)] [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina and Instituto de Física del Plasma (INFIP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires UBA, C1428EHA Buenos Aires (Argentina)

    2013-06-15T23:59:59.000Z

    Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet.

  6. Miniconference on astrophysical jets P. M. Bellan

    E-Print Network [OSTI]

    Bellan, Paul M.

    and numerical modelers of both astrophysical jets and spheromaks, and laboratory experimentalists. The purpose-organization. Spheromaks have been studied for the last two decades and most recently, it has been realized that the physics of spheromak formation has much in common with magnetohydrodynamically driven astrophysical jets

  7. Jet multiplicities as the QGP thermometer

    E-Print Network [OSTI]

    I. M. Dremin; O. S. Shadrin

    2006-02-10T23:59:59.000Z

    It is proposed to use the energy behavior of mean multiplicities of jets propagating in a nuclear medium as the thermometer of this medium during the collision phases. The qualitative effects are demonstrated in the framework of the fixed coupling QCD with account of jet quenching.

  8. $W/Z$ + jets results from CDF

    SciTech Connect (OSTI)

    Camarda, Stefano; /Barcelona, IFAE

    2010-01-01T23:59:59.000Z

    The CDF Collaboration has a comprehensive program of studying the production of vector bosons, W and Z, in association with energetic jets. Excellent understanding of the standard model W/Z+jets and W/Z+c,b-jets processes is of paramount importance for the top quark physics and for the Higgs boson and many new physics searches. We review the latest CDF results on Z-boson production in association with inclusive and b-quark jets, study of the p{sub T} balance in Z+jet events, and a measurement of the W+charm production cross section. The results are based on 4-5 fb{sup -1} of data and compared to various Monte Carlo and next-to-leading order perturbative QCD predictions.

  9. Atmospheric-pressure plasma jet

    DOE Patents [OSTI]

    Selwyn, Gary S. (Los Alamos, NM)

    1999-01-01T23:59:59.000Z

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  10. An inkjet vision measurement technique for high-frequency jetting

    SciTech Connect (OSTI)

    Kwon, Kye-Si, E-mail: kskwon@sch.ac.kr; Jang, Min-Hyuck; Park, Ha Yeong [Department of Mechanical Engineering, Soonchunhyang University 22, Soonchunhyang-Ro, Shinchang, Asan Chungnam 336-745 (Korea, Republic of); Ko, Hyun-Seok [Department of Electrical and Robot Engineering, Soonchunhyang University, 22, Soonchunhyang-Ro, Shinchang, Asan Chungnam 336-745 (Korea, Republic of)

    2014-06-15T23:59:59.000Z

    Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance.

  11. Evidence of critical balance in kinetic Alfven wave turbulence simulations

    SciTech Connect (OSTI)

    TenBarge, J. M.; Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

    2012-05-15T23:59:59.000Z

    A numerical simulation of kinetic plasma turbulence is performed to assess the applicability of critical balance to kinetic, dissipation scale turbulence. The analysis is performed in the frequency domain to obviate complications inherent in performing a local analysis of turbulence. A theoretical model of dissipation scale critical balance is constructed and compared to simulation results, and excellent agreement is found. This result constitutes the first evidence of critical balance in a kinetic turbulence simulation and provides evidence of an anisotropic turbulence cascade extending into the dissipation range. We also perform an Eulerian frequency analysis of the simulation data and compare it to the results of a previous study of magnetohydrodynamic turbulence simulations.

  12. Experimental studies of unbiased gluon jets from $e^{+}e^{-}$ annihilations using the jet boost algorithm

    E-Print Network [OSTI]

    Abbiendi, G; Åkesson, P F; Alexander, G; Allison, J; Amaral, P; Anagnostou, G; Anderson, K J; Arcelli, S; Asai, S; Axen, D A; Azuelos, Georges; Bailey, I; Barberio, E; Barillari, T; Barlow, R J; Batley, J Richard; Bechtle, P; Behnke, T; Bell, K W; Bell, P J; Bella, G; Bellerive, A; Benelli, G; Bethke, Siegfried; Biebel, O; Boeriu, O; Bock, P; Boutemeur, M; Braibant, S; Brigliadori, L; Brown, R M; Büsser, K; Burckhart, H J; Campana, S; Carnegie, R K; Caron, B; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Ciocca, C; Csilling, Akos; Cuffiani, M; Dado, S; de Roeck, A; De Wolf, E A; Desch, Klaus; Dienes, B; Donkers, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Etzion, E; Fabbri, Franco Luigi; Feld, L; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Frey, A; Fürtjes, A; Gagnon, P; Gary, J W; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giunta, M; Goldberg, J; Gross, E; Grunhaus, Jacob; Gruwé, M; Günther, P O; Sen-Gupta, A; Hajdu, C; Hamann, M; Hanson, G G; Harel, A; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Hensel, C; Herten, G; Heuer, R D; Hill, J C; Hoffman, K; Horváth, D; Igo-Kemenes, P; Ishii, K; Jeremie, H; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J; Karlen, Dean A; Kawagoe, K; Kawamoto, T; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Klein, K; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Komamiya, S; Kormos, L L; Kramer, T; Krieger, P; Von Krogh, J; Krüger, K; Kühl, T; Kupper, M; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Layter, J G; Lellouch, D; Letts, J; Levinson, L; Lillich, J; Lloyd, S L; Loebinger, F K; Lü, J; Ludwig, A; Ludwig, J; MacPherson, A; Mader, W; Marcellini, S; Martin, A J; Masetti, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McMahon, T J; McPherson, R A; Meijers, F; Menges, W; Merritt, F S; Mes, H; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Moed, S; Mohr, W; Mori, T; Mutter, A; Nagai, K; Nakamura, I; Nanjo, H; Neal, H A; Nisius, R; O'Neale, S W; Oh, A; Okpara, A N; Oreglia, M J; Orito, S; Pahl, C; Pásztor, G; Pater, J R; Pilcher, J E; Pinfold, J L; Plane, D E; Poli, B; Polok, J; Pooth, O; Przybycien, M B; Quadt, A; Rabbertz, K; Rembser, C; Renkel, P; Roney, J M; Rosati, S; Rozen, Y; Runge, K; Sachs, K; Saeki, T; Sarkisyan-Grinbaum, E; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schörner-Sadenius, T; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Sherwood, P; Skuja, A; Smith, A M; Sobie, R J; Söldner-Rembold, S; Spanó, F; Stahl, A; Stephens, K; Strom, D; Ströhmer, R; Tarem, S; Tasevsky, M; Teuscher, R; Thomson, M A; Torrence, E; Toya, D; Tran, P; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Ujvári, B; Vollmer, C F; Vannerem, P; Vertesi, R; Verzocchi, M; Voss, H; Vossebeld, Joost Herman; Waller, D; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wetterling, D; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Zer-Zion, D; Zivkovic, L

    2004-01-01T23:59:59.000Z

    We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the en...

  13. Anisotropic turbulent model for solar coronal heating

    E-Print Network [OSTI]

    B. Bigot; S. Galtier; H. Politano

    2007-12-12T23:59:59.000Z

    Context : We present a self-consistent model of solar coronal heating, originally developed by Heyvaert & Priest (1992), in which we include the dynamical effect of the background magnetic field along a coronal structure by using exact results from wave MHD turbulence (Galtier et al. 2000). Aims : We evaluate the heating rate and the microturbulent velocity for comparison with observations in the quiet corona, active regions and also coronal holes. Methods :The coronal structures are assumed to be in a turbulent state maintained by the slow erratic motions of the magnetic footpoints. A description for the large-scale and the unresolved small-scale dynamics are given separately. From the latter, we compute exactly (or numerically for coronal holes) turbulent viscosites that are finally used in the former to close self-consistently the system and derive the heating flux expression. Results : We show that the heating rate and the turbulent velocity compare favorably with coronal observations. Conclusions : Although the Alfven wave turbulence regime is strongly anisotropic, and could reduce a priori the heating efficiency, it provides an unexpected satisfactory model of coronal heating for both magnetic loops and open magnetic field lines.

  14. Dark jets in solar coronal holes

    E-Print Network [OSTI]

    Young, Peter R

    2015-01-01T23:59:59.000Z

    A new solar feature termed a dark jet is identified from observations of an extended solar coronal hole that was continuously monitored for over 44 hours by the EUV Imaging Spectrometer on board the Hinode spacecraft in 2011 February 8-10. Line-of-sight velocity maps derived from the coronal Fe XII $\\lambda$195.12 emission line, formed at 1.5 MK, revealed a number of large-scale, jet-like structures that showed significant blueshifts. The structures had either weak or no intensity signal in 193 A filter images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, suggesting that the jets are essentially invisible to imaging instruments. The dark jets are rooted in bright points and occur both within the coronal hole and at the quiet Sun-coronal hole boundary. They exhibit a wide range of shapes, from narrow columns to fan-shaped structures, and sometimes multiple jets are seen close together. A detailed study of one dark jet showed line-of-sight speeds increasing along the jet axis fr...

  15. Jet Reconstruction in Heavy Ion Collisions

    E-Print Network [OSTI]

    Sevil Salur

    2009-05-12T23:59:59.000Z

    Measurements of strong suppression of inclusive hadron distributions and di-hadron correlations at high $p_{T}$, while providing evidence for partonic energy loss, also suffer from geometric biases due to the competition of energy loss and fragmentation. The measurements of fully reconstructed jets is expected to lack these biases as the energy flow is measured independently of the fragmentation details. In this article, we review the recent results from the heavy ion collisions collected by the STAR experiment at RHIC on direct jet reconstruction utilizing the modern sequential recombination and cone jet reconstruction algorithms together with their background subtraction techniques. In order to assess the jet reconstruction biases a comparison with the jet cross section measurement in $\\sqrt{s}=200$ GeV p+p collisions scaled by the number of binary nucleon-nucleon collisions to account for nuclear geometric effects is performed. Comparison of the inclusive jet cross section obtained in central Au+Au events with that in $p+p$ collisions, published previously by STAR, suggests that unbiased jet reconstruction in the complex heavy ion environment indeed may be possible.

  16. Composite Octet Searches with Jet Substructure

    SciTech Connect (OSTI)

    Bai, Yang; /SLAC; Shelton, Jessie; /Yale U.

    2012-02-14T23:59:59.000Z

    Many new physics models with strongly interacting sectors predict a mass hierarchy between the lightest vector meson and the lightest pseudoscalar mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC sensitivity to these new states for the case of QCD octet mesons, considering both two gluon and two b-jet decay modes for the pseudoscalar mesons. We develop both a simple dijet search using only the jet mass and a more sophisticated jet substructure analysis, both of which can discover the composite octets in a dijet-like signature. The reach depends on the mass hierarchy between the vector and pseudoscalar mesons. We find that for the pseudoscalar-to-vector meson mass ratio below approximately 0.2 the simple jet mass analysis provides the best discovery limit; for a ratio between 0.2 and the QCD-like value of 0.3, the sophisticated jet substructure analysis has the best discovery potential; for a ratio above approximately 0.3, the standard four-jet analysis is more suitable.

  17. Jet production in ep collisions Pierre Van Mechelen

    E-Print Network [OSTI]

    Jet production in ep collisions Pierre Van Mechelen University of Antwerpen Pierre electroproduction #12; Jet production in ep collisions Pierre Van Mechelen HERA, H1 and ZEUS H1 ZEUS p (920 GeV) e ± (27.6 GeV) #12; Jet production in ep collisions Pierre Van Mechelen Jet finding algorithms Clustering

  18. Drag, turbulence, and diffusion in flow through emergent vegetation

    E-Print Network [OSTI]

    Nepf, Heidi

    Aquatic plants convert mean kinetic energy into turbulent kinetic energy at the scale of the plant stems and branches. This energy transfer, linked to wake generation, affects vegetative drag and turbulence intensity. ...

  19. Biophysical coupling between turbulence, veliger behavior, and larval supply

    E-Print Network [OSTI]

    Fuchs, Heidi L

    2005-01-01T23:59:59.000Z

    The goals of this thesis were to quantify the behavior of gastropod larvae (mud snails Ilyanassa obsoleta) in turbulence, and to investigate how that behavior affects larval supply in a turbulent coastal inlet. Gastropod ...

  20. Turbulent Flow and Transport Modeling by Long Waves and Currents

    E-Print Network [OSTI]

    Kim, Dae Hong

    2010-10-12T23:59:59.000Z

    This dissertation presents models for turbulent flow and transport by currents and long waves in large domain. From the Navier-Stokes equations, a fully nonlinear depth-integrated equation model for weakly dispersive, turbulent and rotational flow...

  1. Consider Installing Turbulators on Two- and Three-Pass Firetube...

    Broader source: Energy.gov (indexed) [DOE]

    tip sheet outlines the benefits of turbulators on firetube boilers as part of optimized steam systems. STEAM TIP SHEET 25 Consider Installing Turbulators on Two- and Three-Pass...

  2. Vibration of circular plates, of several thicknesses, with three supports

    E-Print Network [OSTI]

    Ballentine, John Richard

    2012-06-07T23:59:59.000Z

    ~ ~ ~ ~ ~ ~ e ~ o ~ ~ i Prccedure and DeeoriPt'alen Of APPSXat'aua ~ ~ e ~ a ~ 0 ~ ~ i EmPirioal Ccrrelabicn Of Dataa ~ ~ ~ 1 ~ ~ ~ 01 ~ ~ ~ ~ ~ ~ ~ ~ i Kathemat, ical Theory of Thin Plates ~ a ~ ~ ~ ~ ~ 1 ~ a ~ ~ ~ Heeultaa ~ ~ ~ ~ ~ a... (cps) e M = symmetric mode, ie. 1, 2, 3, and 4. h= thickness of circular plate, in, Vhen there are mox'e than-thoro variables involved in the x esult, s of an experimental research, an empirical xelat, ionsh1p concerning the several variables may...

  3. Rapid microbial identification by circular intensity differential scattering

    SciTech Connect (OSTI)

    Gregg, C.T.; Salzman, G.C.

    1984-06-01T23:59:59.000Z

    Circular Intensity Differential Scattering (CIDS) is one of the few really new approaches to microbial identification to have come into existence in the past several decades. The CIDS spectra can be measured as a function of wavelength, scattering angle, and/or matrix element, and a number of matrix elements can be measured virtually simultaneously. This panoply of measurements potentially gives the method resolving power for microbial identification. Some representative data taken over the past couple of years on CIDS spectra of several anti-viral vaccines is presented. 17 references; 9 figures.

  4. Comparison of operating speeds at spiral transition and circular curves

    E-Print Network [OSTI]

    Passetti, Karl Andrew

    1998-01-01T23:59:59.000Z

    acceleration, fijs; and V = speed, mph In evaluating the models, it was found that the spiral length increases with increasing speed, but does not become unreasonably long. It was also found that the spiral length and spiral ang e epen o y on 1 d d nl... curves provide deceptive information to drivers is based on crash data for spiral curves, he does not present data for comparable circular curves In addition, the issue of whether the spiral curve is causing the crashes or whether crash rates...

  5. On the circularly polarized optical emission from AE Aquarii

    E-Print Network [OSTI]

    N. R. Ikhsanov; S. Jordan; N. G. Beskrovnaya

    2002-02-14T23:59:59.000Z

    The reported nightly mean value of the circular polarization of optical emission observed from the close binary system AE Aqr is 0.06% (+-) 0.01%. We discuss a possibility that the observed polarized radiation is emitted mainly by the white dwarf or its vicinity. We demonstrate that this hypothesis is rather unlikely since the contribution of the white dwarf to the optical radiation of the system is too small. This indicates that the polarimetric data on AE Aqr cannot be used for the evaluation of the surface magnetic field strength of the white dwarf in this system.

  6. Federal Acquisition Circular 2005-52 Item Subject FAR case

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAX POLICIES ANDIndustrial HygieneEnergyLead-acidPrimusContinued on nextCircular

  7. Federal Acquisition Regulation Federal Acquisition Circular 2005-61

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAX POLICIES ANDIndustrial HygieneEnergyLead-acidPrimusContinued onCircular1

  8. Strong circular photogalvanic effect in ZnO epitaxial films

    SciTech Connect (OSTI)

    Zhang, Q.; Wang, X. Q.; Yin, C. M.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Chen, Y. H.; Chang, K. [Laboratory of Semiconductor Materials Science, Institute of Semiconductors, CAS, Beijing 100083 (China); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)

    2011-12-23T23:59:59.000Z

    A strong circular photogalvanic effect (CPGE) in ZnO epitaxial films was reported under interband excitation. It was observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

  9. Jet physics and the underlying event at the Tevatron

    SciTech Connect (OSTI)

    Field, Rick; /Florida U.

    2005-08-01T23:59:59.000Z

    Tevatron Run 2 results on the inclusive jet cross section (MidPoint and K{sub T} algorithm) and the b-jet and b{bar b}-jet cross section (MidPoint algorithm) are presented and compared with theory. The CDF b-jet {bar b}-jet {Delta}{phi} distribution is compared with theory and with the D0 jet No.1-jet No.2 {Delta}{phi} distribution. The understanding and modeling of the ''underlying event'' in Run 2 at the Tevatron is reviewed and new CDF results are presented.

  10. Jet spoiler arrangement for wind turbine

    DOE Patents [OSTI]

    Cyrus, Jack D. (Corrales, NM); Kadlec, Emil G. (Albuquerque, NM); Klimas, Paul C. (Albuquerque, NM)

    1985-01-01T23:59:59.000Z

    An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

  11. Jet spoiler arrangement for wind turbine

    DOE Patents [OSTI]

    Cyrus, J.D.; Kadlec, E.G.; Klimas, P.C.

    1983-09-15T23:59:59.000Z

    An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

  12. Squark and gluino production with jets

    SciTech Connect (OSTI)

    Plehn, T.; /Munich, Max Planck Inst.; Rainwater, D.; /Rochester U.; Skands, P.; /Fermilab

    2005-10-01T23:59:59.000Z

    We present cross section predictions for squark and gluino production at the LHC, in association with up to two additional hard jets. These cross sections can be very large in comparison to the inclusive Born rates. Because hadron collider experiments utilize hard jets in the reconstruction of cascade decays or as a way to separate squark and gluino production, the understanding of these processes is crucial. We show to what degree hard jet radiation can be described by shower algorithms and point out how tuning these showers, for example to top quark pair production, could help reduce theoretical uncertainties for new physics searches at the LHC.

  13. PDF Calculations of Turbulent Nonpremixed Flames with Local Extinction

    E-Print Network [OSTI]

    , a stochastic model of turbulence frequency, the Euclidean minimum spanning tree (EMST) mixing model, and the 16

  14. Large eddy simulation of turbulence within heat exchangers

    E-Print Network [OSTI]

    Pruitt, John Myron

    2012-06-07T23:59:59.000Z

    be problematic if the turbulent energy is near the tubes natural frequency. However, as compared to the drag force exerted by the fluid, vortex shedding and turbulent buffeting are are of lesser significance than fluid elastic instability. Fluid elastic... on turbulent statistics. Is is widely accepted that there are four basic sources of cross-flow excitation in tube banks: vortex shedding, turbulent buffeting, fluid-elastic instability, and acoustic resonance (Grover et aL 1978). Vortex shedding is a...

  15. Physics of Stratocumulus Top (POST): turbulent mixing across capping inversion

    E-Print Network [OSTI]

    2013-01-01T23:59:59.000Z

    vertical water potential horizontal wind, and turbulentof potential components of horizontal wind, and buoyantwater potential temperature, horizontal wind, and turbulent

  16. Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids

    E-Print Network [OSTI]

    Yirak, Kristopher; Cunningham, Andrew J; Mitran, Sorin

    2008-01-01T23:59:59.000Z

    Herbig-Haro (HH) jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or ``pulsed'' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper we offer an alternative to ``pulsed'' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of sub-radial clumps propagating through a moving inter-clump medium. Our models explore an idealization of this scenario by injecting small ($r\\rho_{jet}$) spheres embedded in an otherwise smooth inter-clump jet flow. The spheres are initialized with velocities differing from the jet velocity by $\\sim15$%. We find the consequences of shiftin...

  17. Wave turbulence served up on a plate

    E-Print Network [OSTI]

    Pablo Cobelli; Philippe Petitjeans; Agnes Maurel; Vincent Pagneux; Nicolas Mordant

    2009-10-28T23:59:59.000Z

    Wave turbulence in a thin elastic plate is experimentally investigated. By using a Fourier transform profilometry technique, the deformation field of the plate surface is measured simultaneously in time and space. This enables us to compute the wavevector-frequency Fourier ($\\mathbf k, \\omega$) spectrum of the full space-time deformation velocity. In the 3D ($\\mathbf k, \\omega$) space, we show that the energy of the motion is concentrated on a 2D surface that represents a nonlinear dispersion relation. This nonlinear dispersion relation is close to the linear dispersion relation. This validates the usual wavenumber-frequency change of variables used in many experimental studies of wave turbulence. The deviation from the linear dispersion, which increases with the input power of the forcing, is attributed to weak non linear effects. Our technique opens the way for many new extensive quantitative comparisons between theory and experiments of wave turbulence.

  18. Boundary Plasma Turbulence Simulations for Tokamaks

    SciTech Connect (OSTI)

    Xu, X; Umansky, M; Dudson, B; Snyder, P

    2008-05-15T23:59:59.000Z

    The boundary plasma turbulence code BOUT models tokamak boundary-plasma turbulence in a realistic divertor geometry using modified Braginskii equations for plasma vorticity, density (ni), electron and ion temperature (T{sub e}; T{sub i}) and parallel momenta. The BOUT code solves for the plasma fluid equations in a three dimensional (3D) toroidal segment (or a toroidal wedge), including the region somewhat inside the separatrix and extending into the scrape-off layer; the private flux region is also included. In this paper, a description is given of the sophisticated physical models, innovative numerical algorithms, and modern software design used to simulate edge-plasmas in magnetic fusion energy devices. The BOUT code's unique capabilities and functionality are exemplified via simulations of the impact of plasma density on tokamak edge turbulence and blob dynamics.

  19. Spatial and Spectral evolution of Turbulence Spectra

    SciTech Connect (OSTI)

    Guercan, Oe. D.; Diamond, P. H. [Center for Astrophysics and Space Sciences, La Jolla, CA 92093-0424 (United States); Department of Physics University of California at San Diego, La Jolla, CA 92093-0424 (United States); Department of Physics, University of California at San Diego, La Jolla, CA 92093-0319 (United States); Hahm, T. S. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States)

    2006-11-30T23:59:59.000Z

    We present a general formulation of a theory of spreading of turbulence based on nonlinear mode couplings, which is inherently linked to spectral evolution. We present a derivation from simple two-field perspective based upon a gradien diffusion hypothesis, justified by a two scale direct interaction approximation (TSDIA) for weak turbulence. The complexity and anisotropy of spatial and spectral dynamics, however, limits our analysis to examination of different classes of triad interactions. We demonstrate that radially extended eddys, are the most effective structures in promoting spreading of turbulence. Thus, spectral evolution that tends towards such eddies, facilitate spatial spreading. We also show that, in a two field model, due to their respective spectral tendencies, internal energy spreads faster than kinetic energy.

  20. Turbulence attenuation by large neutrally buoyant particles

    E-Print Network [OSTI]

    Cisse, Mamadou; Gibert, Mathieu; Bodenschatz, Eberhard; Bec, Jeremie

    2015-01-01T23:59:59.000Z

    Turbulence modulation by inertial-range-size, neutrally-buoyant particles is investigated experimentally in a von K\\'arm\\'an flow. Increasing the particle volume fraction $\\Phi_\\mathrm{v}$, maintaining constant impellers Reynolds number attenuates the fluid turbulence. The inertial-range energy transfer rate decreases as $\\propto\\Phi_\\mathrm{v}^{2/3}$, suggesting that only particles located on a surface affect the flow. Small-scale turbulent properties, such as structure functions or acceleration distribution, are unchanged. Finally, measurements hint at the existence of a transition between two different regimes occurring when the average distance between large particles is of the order of the thickness of their boundary layers.

  1. Universal equations and constants of turbulent motion

    E-Print Network [OSTI]

    Baumert, Helmut Z

    2012-01-01T23:59:59.000Z

    This paper presents a parameter-free theory of shear-generated turbulence at asymptotically high Reynolds numbers in incompressible fluids. It is based on a two-fluids concept. Both components are materially identical and inviscid. The first component is an ensemble of quasi-rigid dipole-vortex tubes as quasi-particles in chaotic motion. The second is a superfluid performing evasive motions between the tubes. The local dipole motions follow Helmholtz' law. The vortex radii scale with the energy-containing length scale. Collisions between quasi-particles lead either to annihilation (likewise rotation, turbulent dissipation) or to scattering (counterrotation, turbulent diffusion). There are analogies with birth and death processes of population dynamics and their master equations. For free homogeneous decay the theory predicts the TKE to follow 1/t. With an adiabatic condition at the wall it predicts the logarithmic law with von Karman's constant as 1/\\sqrt{2 pi} = 0.399. Likewise rotating couples form dissipat...

  2. A signature for turbulence driven magnetic islands

    SciTech Connect (OSTI)

    Agullo, O.; Muraglia, M.; Benkadda, S. [Aix-Marseille Université, CNRS, PIIM, UMR 7345 Marseille (France); France-Japan Magnetic Fusion Laboratory, LIA 336 CNRS, Marseille (France); Poyé, A. [Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Yagi, M. [Plasma Theory and Simulation Gr., JAEA, Rokkasho (Japan); Garbet, X. [IRFM, CEA, St-Paul-Lez-Durance 13108 (France); Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2014-09-15T23:59:59.000Z

    We investigate the properties of magnetic islands arising from tearing instabilities that are driven by an interchange turbulence. We find that such islands possess a specific signature that permits an identification of their origin. We demonstrate that the persistence of a small scale turbulence maintains a mean pressure profile, whose characteristics makes it possible to discriminate between turbulence driven islands from those arising due to an unfavourable plasma current density gradient. We also find that the island poloidal turnover time, in the steady state, is independent of the levels of the interchange and tearing energy sources. Finally, we show that a mixing length approach is adequate to make theoretical predictions concerning island flattening in the island rotation frame.

  3. A circular equilibrium model for local gyrokinetic simulations of ion temperature gradient fluctuations in reversed field pinches

    SciTech Connect (OSTI)

    Tangri, Varun; Terry, P. W. [Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706R (United States); Waltz, R. E. [General Atomics, San Diego, California 92186 (United States)

    2011-05-15T23:59:59.000Z

    A simple large-aspect-ratio (R{sub 0}/r) circular equilibrium model is developed for low-beta reversed field pinch (RFP) geometry. The model is suitable for treating small scale instability and turbulent transport driven by ion temperature gradient (ITG) and related electron drift modes in gyrokinetic simulations. The equilibrium model is an RFP generalization of the common tokamak s-{alpha} model to small safety factor (q), where the poloidal field dominates the toroidal field. The model accommodates the RFP toroidal field reversal (where q vanishes) by generalizing the cylindrical force-free Bessel function model (BFM) [J. B. Taylor, Phys. Rev. Lett. 33, 1139 (1974)] to toroidal geometry. The global equilibrium can be described in terms of the RFP field reversal and pinch parameters [F,{Theta}]. This new toroidal Bessel function model (TBFM) has been incorporated into the gyrokinetic code GYRO [J. Candy and R. E. Waltz, J.Comput. Phys. 186, 545 (2003)] and used here to explore local electrostatic ITG adiabatic electron instability rates for typical low-q RFP parameters.

  4. Figure 2: The mercury jet target geometry. The proton beam and mercury jet cross at z=-37.5 cm.

    E-Print Network [OSTI]

    McDonald, Kirk

    Figure 2: The mercury jet target geometry. The proton beam and mercury jet cross at z=-37.5 cm. Figure 3: The layout of multiple proton beam entry directions relative to mercury jet at z=-75 cm. A PION of a free liquid mercury jet with an intense proton beam. We study the variation of meson production

  5. Statistical theory of turbulent incompressible multimaterial flow

    SciTech Connect (OSTI)

    Kashiwa, B.

    1987-10-01T23:59:59.000Z

    Interpenetrating motion of incompressible materials is considered. ''Turbulence'' is defined as any deviation from the mean motion. Accordingly a nominally stationary fluid will exhibit turbulent fluctuations due to a single, slowly moving sphere. Mean conservation equations for interpenetrating materials in arbitrary proportions are derived using an ensemble averaging procedure, beginning with the exact equations of motion. The result is a set of conservation equations for the mean mass, momentum and fluctuational kinetic energy of each material. The equation system is at first unclosed due to integral terms involving unknown one-point and two-point probability distribution functions. In the mean momentum equation, the unclosed terms are clearly identified as representing two physical processes. One is transport of momentum by multimaterial Reynolds stresses, and the other is momentum exchange due to pressure fluctuations and viscous stress at material interfaces. Closure is approached by combining careful examination of multipoint statistical correlations with the traditional physical technique of kappa-epsilon modeling for single-material turbulence. This involves representing the multimaterial Reynolds stress for each material as a turbulent viscosity times the rate of strain based on the mean velocity of that material. The multimaterial turbulent viscosity is related to the fluctuational kinetic energy kappa, and the rate of fluctuational energy dissipation epsilon, for each material. Hence a set of kappa and epsilon equations must be solved, together with mean mass and momentum conservation equations, for each material. Both kappa and the turbulent viscosities enter into the momentum exchange force. The theory is applied to (a) calculation of the drag force on a sphere fixed in a uniform flow, (b) calculation of the settling rate in a suspension and (c) calculation of velocity profiles in the pneumatic transport of solid particles in a pipe.

  6. Electron Thermal Transport in Tokamak: ETG or TEM Turbulences?

    E-Print Network [OSTI]

    Zonca, Fulvio

    Electron Thermal Transport in Tokamak: ETG or TEM Turbulences? Z. Lin, L. Chen, Y. Nishimura, H. Qu studies of electron transport in tokamak including: (1) electron temperature gradient turbulence; (2) trapped electron mode turbulence; and (3) a new finite element solver for global electromagnetic

  7. Di-jet hadron pair correlation in a hydrodynamical model with a quenching jet

    E-Print Network [OSTI]

    A. K. Chaudhuri

    2008-01-15T23:59:59.000Z

    In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium, leading to suppressed production of high-$p_T$ hadrons. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. Hydrodynamic evolution and subsequent particle emission depend on the jet trajectories. Azimuthal distribution of excess $\\pi^-$ due to quenching jet, averaged over all the trajectories, reasonably well reproduce the di-hadron correlation as measured by the STAR and PHENIX collaboration in central and in peripheral Au+Au collisions.

  8. NEAR-INFRARED CIRCULAR POLARIZATION IMAGES OF NGC 6334-V

    SciTech Connect (OSTI)

    Kwon, Jungmi; Tamura, Motohide; Hashimoto, Jun; Kusakabe, Nobuhiko; Kandori, Ryo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Lucas, Phil W.; Hough, James H. [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nakajima, Yasushi [Center of Information and Communication Technology, Hitotsubashi University, 2-1 Naka, Kunitachi, Tokyo 186-8601 (Japan); Nagayama, Takahiro [Department of Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Nagata, Tetsuya, E-mail: jungmi.kwon@nao.ac.jp [Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan)

    2013-03-01T23:59:59.000Z

    We present results from deep imaging linear and circular polarimetry of the massive star-forming region NGC 6334-V. These observations show high degrees of circular polarization (CP), as much as 22% in the K{sub s} band, in the infrared nebula associated with the outflow. The CP has an asymmetric positive/negative pattern and is very extended ({approx}80'' or 0.65 pc). Both the high CP and its extended size are larger than those seen in the Orion CP region. Three-dimensional Monte Carlo light-scattering models are used to show that the high CP may be produced by scattering from the infrared nebula followed by dichroic extinction by an optically thick foreground cloud containing aligned dust grains. Our results show not only the magnetic field orientation of around young stellar objects, but also the structure of circumstellar matter such as outflow regions and their parent molecular cloud along the line of sight. The detection of the large and extended CP in this source and the Orion nebula may imply the CP origin of the biological homochirality on Earth.

  9. Feasibility Study for a New Business Jet

    E-Print Network [OSTI]

    Mousa, Yasser Abdullah

    2009-05-15T23:59:59.000Z

    This report demonstrates details of a feasibility study of a new business jet as an effort to complete the requirements for a field project (EMGT 835) in Engineering Management. The study is conducted during global economic crisis to identify a...

  10. Inclusive jet cross section at CDF

    SciTech Connect (OSTI)

    Lefevre, R.; Martinez, M.; /Barcelona, IFAE

    2005-01-01T23:59:59.000Z

    This contribution reports on preliminary measurements of the inclusive jet production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using data collected with CDF corresponding to an integrated luminosity of 385 pb{sup -1}. Two analyzes are presented: one uses the longitudinally invariant k{sub T} algorithm to reconstruct the jets, the other uses the midpoint algorithm. Both are limited to jets with rapidity in the range 0.1 < |y{sup jet}| < 0.7. The measured cross sections are in good agreement with next-to-leading order perturbative QCD predictions after including the non-perturbative corrections necessary to account for underlying event and hadronization effects.

  11. E-Print Network 3.0 - alters jejunal circular Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    circular or replication form intermediates, respectively. UV ... Source: Engelhardt, John F. - Department of Anatomy and Cell Biology, University of Iowa Collection: Biology...

  12. E-Print Network 3.0 - administrative circulars rev Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    >> 1 Virginia Polytechnic Institute and State University No. 3240 Rev.: 1 Policy and Procedures Date: February 15, 2005 Summary: similar costs. Circular A-21, Section F.6.b....

  13. Analysis of the multipactor effect in circular waveguides excited by two orthogonal polarization waves

    SciTech Connect (OSTI)

    Pérez, A. M.; Boria, V. E. [Departamento de Comunicaciones-iTEAM, Universidad Politécnica de Valencia Camino de Vera s/n, 46022 Valencia (Spain); Gimeno, B. [Departamento de Física Aplicada y Electromagnetismo-ICMUV, Universitat de València c/Dr. Moliner, 50, 46100 Valencia (Spain); Anza, S.; Vicente, C.; Gil, J. [Aurora Software and Testing S.L., Edificio de Desarrollo Empresarial 9B, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2014-08-15T23:59:59.000Z

    Circular waveguides, either employed as resonant cavities or as irises connecting adjacent guides, are widely present in many passive components used in different applications (i.e., particle accelerators and satellite subsystems). In this paper, we present the study of the multipactor effect in circular waveguides considering the coexistence of the two polarizations of the fundamental TE{sub 11} circular waveguide mode. For a better understanding of the problem, only low multipactor orders have been explored as a function of the polarization ellipse eccentricity. Special attention has been paid to the linear and circular polarizations, but other more general configurations have also been explored.

  14. Measuring collinear W emissions inside jets

    E-Print Network [OSTI]

    Frank Krauss; Petar Petrov; Marek Schoenherr; Michael Spannowsky

    2014-03-19T23:59:59.000Z

    Single and multiple emission of electroweak gauge bosons and in particular of W bosons is discussed in the parton shower language. Algorithms and observables for the reconstruction of both leptonically and hadronically decaying W bosons inside light quark jets are compared, and they are applied to a study of how emission rates of W bosons in light-jet events at the LHC could be measured.

  15. New results on jet fragmentation at CDF

    SciTech Connect (OSTI)

    Jindariani, Sergo; /Florida U.

    2006-12-01T23:59:59.000Z

    Presented are the latest results of jet fragmentation studies at the Tevatron using the CDF Run II detector. Studies include the distribution of transverse momenta (Kt) of particles jets, two-particle momentum correlations, and indirectly global event shapes in p{bar p} collisions. Results are discussed within the context of recent Next-to-Leading Log calculations as well as earlier experimental results from the Tevatron and e{sup +}e{sup -} colliders.

  16. Cosmic-Ray Acceleration at Ultrarelativistic Shock Waves: Effects of Downstream Short-Wave Turbulence

    E-Print Network [OSTI]

    Jacek Niemiec; Michal Ostrowski; Martin Pohl

    2006-03-14T23:59:59.000Z

    The present paper is the last of a series studying the first-order Fermi acceleration processes at relativistic shock waves with the method of Monte Carlo simulations applied to shocks propagating in realistically modeled turbulent magnetic fields. The model of the background magnetic field structure of Niemiec & Ostrowski (2004, 2006) has been augmented here by a large-amplitude short-wave downstream component, imitating that generated by plasma instabilities at the shock front. Following Niemiec & Ostrowski (2006), we have considered ultrarelativistic shocks with the mean magnetic field oriented both oblique and parallel to the shock normal. For both cases simulations have been performed for different choices of magnetic field perturbations, represented by various wave power spectra within a wide wavevector range. The results show that the introduction of the short-wave component downstream of the shock is not sufficient to produce power-law particle spectra with the "universal" spectral index 4.2. On the contrary, concave spectra with cutoffs are preferentially formed, the curvature and cutoff energy being dependent on the properties of turbulence. Our results suggest that the electromagnetic emission observed from astrophysical sites with relativistic jets, e.g. AGN and GRBs, is likely generated by particles accelerated in processes other than the widely invoked first-order Fermi mechanism.

  17. The Infrared Jet in 3C31

    E-Print Network [OSTI]

    Lanz, Lauranne; Kraft, Ralph P; Birkinshaw, Mark; Lal, Dharam V; Forman, William R; Jones, Christine; Worrall, Diana M

    2015-01-01T23:59:59.000Z

    We report the detection of infrared emission from the jet of the nearby FR I radio galaxy 3C 31. The jet was detected with the IRAC instrument on Spitzer at 4.5 micron, 5.8 micron, and 8.0 micron out to 30" (13 kpc) from the nucleus. We measure radio, infrared, optical, and X-ray fluxes in three regions along the jet determined by the infrared and X-ray morphology. Radio through X-ray spectra in these regions demonstrate that the emission can be interpreted as synchrotron emission from a broken power-law distribution of electron energies. We find significant differences in the high energy spectra with increasing distance from the nucleus. Specifically, the high energy slope increases from 0.86 to 1.72 from 1 kpc to 12 kpc along the jet, and the spectral break likewise increases in frequency along the jet from 10-100's of GHz to ~20 THz. Thus the ratio of IR to X-ray flux in the jet increases by at least an order of magnitude with increasing distance from the nucleus. We argue that these changes cannot simply ...

  18. Final Report - Investigation of Intermittent Turbulence and Turbulent Structures in the Presence of Controlled Sheared Flows

    SciTech Connect (OSTI)

    Gilmore, Mark A. [University of New Mexico

    2013-06-27T23:59:59.000Z

    Final Report for grant DE-FG02-06ER54898. The dynamics and generation of intermittent plasma turbulent structures, widely known as "blobs" have been studied in the presence of sheared plasma flows in a controlled laboratory experiment.

  19. Calculation of unsteady turbulent flow around obstacles using the large eddy simulation turbulence model

    E-Print Network [OSTI]

    Helton, Donald McLean

    2002-01-01T23:59:59.000Z

    The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with a prevalent turbulence model, Large Eddy Simulation (LES), to study the flow past rectangular cylinders. In an attempt to use...

  20. A turbulence model for buoyant flows based on vorticity generation.

    SciTech Connect (OSTI)

    Domino, Stefan Paul; Nicolette, Vernon F.; O'Hern, Timothy John; Tieszen, Sheldon R.; Black, Amalia Rebecca

    2005-10-01T23:59:59.000Z

    A turbulence model for buoyant flows has been developed in the context of a k-{var_epsilon} turbulence modeling approach. A production term is added to the turbulent kinetic energy equation based on dimensional reasoning using an appropriate time scale for buoyancy-induced turbulence taken from the vorticity conservation equation. The resulting turbulence model is calibrated against far field helium-air spread rate data, and validated with near source, strongly buoyant helium plume data sets. This model is more numerically stable and gives better predictions over a much broader range of mesh densities than the standard k-{var_epsilon} model for these strongly buoyant flows.

  1. On Challenges for Hypersonic Turbulent Simulations

    SciTech Connect (OSTI)

    Yee, H C; Sjogreen, B

    2009-01-14T23:59:59.000Z

    This short note discusses some of the challenges for design of suitable spatial numerical schemes for hypersonic turbulent flows, including combustion, and thermal and chemical nonequilibrium flows. Often, hypersonic turbulent flows in re-entry space vehicles and space physics involve mixed steady strong shocks and turbulence with unsteady shocklets. Material mixing in combustion poses additional computational challenges. Proper control of numerical dissipation in numerical methods beyond the standard shock-capturing dissipation at discontinuities is an essential element for accurate and stable simulations of the subject physics. On one hand, the physics of strong steady shocks and unsteady turbulence/shocklet interactions under the nonequilibrium environment is not well understood. On the other hand, standard and newly developed high order accurate (fourth-order or higher) schemes were developed for homogeneous hyperbolic conservation laws and mixed hyperbolic and parabolic partial differential equations (PDEs) (without source terms). The majority of finite rate chemistry and thermal nonequilibrium simulations employ methods for homogeneous time-dependent PDEs with a pointwise evaluation of the source terms. The pointwise evaluation of the source term might not be the best choice for stability, accuracy and minimization of spurious numerics for the overall scheme.

  2. Inertial range turbulence in kinetic plasmas

    E-Print Network [OSTI]

    G. G. Howes

    2007-11-27T23:59:59.000Z

    The transfer of turbulent energy through an inertial range from the driving scale to dissipative scales in a kinetic plasma followed by the conversion of this energy into heat is a fundamental plasma physics process. A theoretical foundation for the study of this process is constructed, but the details of the kinetic cascade are not well understood. Several important properties are identified: (a) the conservation of a generalized energy by the cascade; (b) the need for collisions to increase entropy and realize irreversible plasma heating; and (c) the key role played by the entropy cascade--a dual cascade of energy to small scales in both physical and velocity space--to convert ultimately the turbulent energy into heat. A strategy for nonlinear numerical simulations of kinetic turbulence is outlined. Initial numerical results are consistent with the operation of the entropy cascade. Inertial range turbulence arises in a broad range of space and astrophysical plasmas and may play an important role in the thermalization of fusion energy in burning plasmas.

  3. Comparison of anemometers for turbulence characterization

    SciTech Connect (OSTI)

    Morris, V.R.; Barnard, J.C.; Wendell, L.L.; Tomich, S.D.

    1992-10-01T23:59:59.000Z

    During the first phase of the US Department of Energy's turbulence characterization program, important discoveries were made about the field application of propeller-vane and cup anemometers under very turbulent conditions. First, averaged speeds measured by the propeller-vane anemometer were consistently lower than those from the cup anemometer, even though both registered virtually the same during wind-tunnel calibration testing. Second, the propeller-vane anemometers suffered from structural failures much more frequently than the cup anemometers. The difficulties associated with the use of the propeller-vane motivated us to consider the cup anemometer for turbulence measurements. At fast sample rates, the output of the cup anemometer is severely degraded by discretization error that stems from pulse counting demodulation. However, we found that a low-pass Gaussian filter could be applied to the time series of wind speed derived from the cup anemometer to yield time series and frequency spectra that compared very favorably with those obtained from the propeller-vane anemometer. This finding suggests that the cup anemometer may prove to be an inexpensive and rugged sensor appropriate for turbulence measurements for wind-energy applications.

  4. AMBIPOLAR DIFFUSION HEATING IN TURBULENT SYSTEMS

    SciTech Connect (OSTI)

    Li, Pak Shing [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Myers, Andrew [Physics Department, University of California, Berkeley, CA 94720 (United States); McKee, Christopher F., E-mail: psli@astron.berkeley.edu, E-mail: atmyers@berkeley.edu, E-mail: cmckee@berkeley.edu [Physics Department and Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2012-11-20T23:59:59.000Z

    The temperature of the gas in molecular clouds is a key determinant of the characteristic mass of star formation. Ambipolar diffusion (AD) is considered one of the most important heating mechanisms in weakly ionized molecular clouds. In this work, we study the AD heating rate using two-fluid turbulence simulations and compare it with the overall heating rate due to turbulent dissipation. We find that for observed molecular clouds, which typically have Alfven Mach numbers of {approx}1 and AD Reynolds numbers of {approx}20, about 70% of the total turbulent dissipation is in the form of AD heating. AD has an important effect on the length scale where energy is dissipated: when AD heating is strong, most of the energy in the cascade is removed by ion-neutral drift, with a comparatively small amount of energy making it down to small scales. We derive a relation for the AD heating rate that describes the results of our simulations to within a factor of two. Turbulent dissipation, including AD heating, is generally less important than cosmic-ray heating in molecular clouds, although there is substantial scatter in both.

  5. Optical monitor for observing turbulent flow

    DOE Patents [OSTI]

    Albrecht, Georg F. (Livermore, CA); Moore, Thomas R. (Rochester, NY)

    1992-01-01T23:59:59.000Z

    The present invention provides an apparatus and method for non-invasively monitoring turbulent fluid flows including anisotropic flows. The present invention uses an optical technique to filter out the rays travelling in a straight line, while transmitting rays with turbulence induced fluctuations in time. The output is two dimensional, and can provide data regarding the spectral intensity distribution, or a view of the turbulence in real time. The optical monitor of the present invention comprises a laser that produces a coherent output beam that is directed through a fluid flow, which phase-modulates the beam. The beam is applied to a temporal filter that filters out the rays in the beam that are straight, while substantially transmitting the fluctuating, turbulence-induced rays. The temporal filter includes a lens and a photorefractive crystal such as BaTiO.sub.3 that is positioned in the converging section of the beam near the focal plane. An imaging system is used to observe the filtered beam. The imaging system may take a photograph, or it may include a real time camera that is connected to a computer. The present invention may be used for many purposes including research and design in aeronautics, hydrodynamics, and combustion.

  6. 6, 52515268, 2006 Turbulent fluxes over

    E-Print Network [OSTI]

    Boyer, Edmond

    ´exico, 04510 Mexico City, Mexico Received: 24 March 2006 ­ Accepted: 10 May 2006 ­ Published: 26 June 2006 wind speed conditions (up to 25 ms -1 ). The estimates of total momentum flux and turbulent kinetic energy can be represented very5 accurately (r2 =0.99, when data are binned every 1 ms-1 ) by empirical

  7. Helicity within the Kolmogorov phenomenology of turbulence

    E-Print Network [OSTI]

    Kurien, Susan

    Helicity within the Kolmogorov phenomenology of turbulence Susan Kurien Mathematical Modeling@lanl.gov In a phenomenology in which both energy and helicity exhibit net flux to the small scales it is natural in resolved numerical simulations in [4]. In a phenomenology in which both energy and helicity exhibit net

  8. OF HEALTH CARE IN TURBULENT TIMES

    E-Print Network [OSTI]

    Feschotte, Cedric

    FIXING THE FLOW OF HEALTH CARE IN TURBULENT TIMES INNOVATION REPORT 2014 #12;Since 2012, Algorithms facing health care today. We believe there's an unprecedented opportunity to invent a new vision for health care, and academic medicine is poised to lead the way. Algorithms for Innovations is designed

  9. Power spectra of outflow-driven turbulence

    E-Print Network [OSTI]

    Moraghan, Anthony; Yoon, Suk-Jin

    2015-01-01T23:59:59.000Z

    We investigate the power spectra of outflow-driven turbulence through high-resolution three-dimensional isothermal numerical simulations where the turbulence is driven locally in real-space by a simple spherical outflow model. The resulting turbulent flow saturates at an average Mach number of ~2.5 and is analysed through density and velocity power spectra, including an investigation of the evolution of the solenoidal and compressional components. We obtain a shallow density power spectrum with a slope of ~-1.2 attributed to the presence of a network of localised dense filamentary structures formed by strong shock interactions. The total velocity power spectrum slope is found to be ~-2.0, representative of Burgers shock dominated turbulence model. The density weighted velocity power spectrum slope is measured as ~-1.6, slightly less than the expected Kolmogorov scaling value (slope of -5/3) found in previous works. The discrepancy may be caused by the nature of our real space driving model and we suggest ther...

  10. Electron acceleration and turbulence in solar

    E-Print Network [OSTI]

    University College London

    , 2005 Free magnetic energy ~2 1032 ergs #12;"Standard" model of a solar flare/CME Solar corona T ~ 106 K Electron energies >10 MeV Proton energies >100 MeV Large solar flare releases about 1032 ergs (about halfElectron acceleration and turbulence in solar flares Eduard Kontar School of Physics and Astronomy

  11. Universal constants and equations of turbulent motion

    E-Print Network [OSTI]

    Baumert, Helmut Z

    2011-01-01T23:59:59.000Z

    In the spirit of Prandtl [1926], for turbulence at high Reynolds number we present an analogy with the kinetic theory of gases, with dipoles made of Thorpe's [1977] quasi-solid vortex tubes as frictionless, incompressible but deformable quasi-particles. Their movements are governed by Helmholtz' elementary vortex rules applied locally. A contact interaction or 'collision' leads either to random scatter of a trajectory or to the formation of two likewise rotating, fundamentally unstable whirls forming a dissipative patch slowly rotating around its center of mass which is almost at rest. This approach predicts von Karman's constant as 1/sqrt(2 pi) = 0.399 and the spatio-temporal dynamics of energy-containing time and length scales controlling turbulent mixing Baumert [2009]. A link to turbulence spectra was missing so far. In the present paper it is shown that the above image of random vortex-dipole movements is compatible with Kolmogorov's turbulence spectra if dissipative patches, beginning as two likewise ro...

  12. Colloidal particle deposition in turbulent flow

    SciTech Connect (OSTI)

    Morton, D.S.

    1994-05-01T23:59:59.000Z

    A theoretical analysis is presented which describes the initial deposition of monodispersed spherical colloidal particles from a steady fully developed turbulent flow onto conduit walls. When the net particle-conduit electrical interaction potential is attractive, particle deposition is shown to be often governed by turbulent hydrodynamics. When the net particle-conduit electrical interaction potential possess a repulsive maximum, particle deposition to first order is uniform and depends solely on electrical interaction effects. The developed theoretical model specialized to orifice deposition with the use of Harwell Flow3D turbulence modelling software qualitatively described the deposition of 0.5 {mu}m silica particles onto glass orifices from an aqueous suspension. The effect of the electrical double layer on the rate of colloidal particle deposition in laminar flow has been described by Spielman and Friedlander (1), Dahneke (2), Bowen et al. (3) and Bowen and Epstein (4). This article describes the extension of their work to colloidal particle deposition under steady fully developed turbulent flow conditions. This article also reports the results of orifice particle deposition experiments which were conducted to qualitatively investigate the developed theoretical model.

  13. Combustion-turbulence interaction in the turbulent boundary layer over a hot surface

    SciTech Connect (OSTI)

    Ng, T.T.; Cheng, R.K.; Robben, F.; Talbot, L.

    1982-01-01T23:59:59.000Z

    The turbulence-combustion interaction in a reacting turbulent boundary layer over a heated flat plate was studied. Ethylene/air mixture with equivalence ratio of 0.35 was used. The free stream velocity was 10.5 m/s and the wall temperature was 1250/sup 0/K. Combustion structures visualization was provided by high-speed schlieren photographs. Fluid density statistics were deduced from Rayleigh scattering intensity measurements. A single-component laser Doppler velocimetry system was used to obtain mean and root-mean-square velocity distributions, the Reynolds stress, the streamwise and the cross-stream turbulent kinetic energy diffusion, and the production of turbulent kinetic energy by Reynolds stress. The combustion process was dominated by large-scale turbulent structures of the boundary layer. Combustion causes expansion of the boundary layer. No overall self-similarity is observed in either the velocity or the density profiles. Velocity fluctuations were increased in part of the boundary layer and the Reynolds stress was reduced. The turbulent kinetic energy diffusion pattern was changed significantly and a modification of the boundary layer assumption will be needed when dealing with this problem analytically. 11 figures, 1 table.

  14. A Dynamical Model of Plasma Turbulence in the Solar Wind

    E-Print Network [OSTI]

    Howes, G G

    2015-01-01T23:59:59.000Z

    A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures in kinetic plasma turbulence. It is argued that the linear and nonlinear dynamics of Alfven waves are responsible, at a very fundamental level, for some of the key qualitative features of plasma turbulence that distinguish it from hydrodynamic turbulence, including the anisotropic cascade of energy and the development of current sheets at small scales. The first dynamical model of kinetic turbulence in the weakly collisional solar wind plasma that combines self-consistently the physics of Alfven waves with the development of small-scale current sheets is presented and its physical implications are discussed. This model leads to a simplified perspective on the nature of turbulence in a weakly collisional plasma: the nonlinear interactions responsible for the turbulent casca...

  15. Sound Waves from Quenched Jets

    E-Print Network [OSTI]

    Vladimir Khachatryan; Edward Shuryak

    2011-08-15T23:59:59.000Z

    Heavy ion collisions at RHIC/LHC energies are well described by the (nearly ideal) hydrodynamics. Last year this success has been extended to higher angular harmonics, $v_n,n=3..9$ induced by initial-state perturbations, in analogy to cosmic microwave background fluctuations. Here we use hydrodynamics to study sound propagation emitted by quenched jets. We use the so called "geometric acoustics" to follow the sound propagation, on top of the expanding fireball. The conical waves, known as "Mach cones", turn out to be strongly distorted. We show that large radial flow makes the observed particle spectra to be determined mostlly by the vicinity of their intersection with the fireball's space-like and time-like freezeout surfaces. We further show how the waves modify the freezeout surfaces and spectra. We end up comparing our calculations to the two-particle correlation functions at RHIC, while emphasizing that studies of dijet events observed at LHC should provide much better test of our theory.

  16. PHOTOSPHERIC EMISSION FROM STRATIFIED JETS

    SciTech Connect (OSTI)

    Ito, Hirotaka; Nagataki, Shigehiro; Ono, Masaomi; Lee, Shiu-Hang; Mao, Jirong [Astrophysical Big Bang Laboratory, RIKEN, Saitama 351-0198 (Japan); Yamada, Shoichi [Department of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Pe'er, Asaf [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mizuta, Akira [KEK Theory Center, Tsukuba 305-0801 (Japan); Harikae, Seiji, E-mail: hito@yukawa.kyoto-u.ac.jp [Quants Research Department, Financial Engineering Division, Mitsubishi UFJ Morgan Stanley Securities Co., Ltd., Mejirodai Bldg., 3-29-20 Mejirodai, Bunkyo-ku, Tokyo 112-8688 (Japan)

    2013-11-01T23:59:59.000Z

    We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. Thermal photons are injected in regions of high optical depth and propagated until the photons escape at the photosphere. Because of the presence of shear in velocity (Lorentz factor) at the boundary of the spine and sheath region, a fraction of the injected photons are accelerated using a Fermi-like acceleration mechanism such that a high-energy power-law tail is formed in the resultant spectrum. We show, in particular, that if a velocity shear with a considerable variance in the bulk Lorentz factor is present, the high-energy part of observed gamma-ray bursts (GRBs) photon spectrum can be explained by this photon acceleration mechanism. We also show that the accelerated photons might also account for the origin of the extra-hard power-law component above the bump of the thermal-like peak seen in some peculiar bursts (e.g., GRB 090510, 090902B, 090926A). We demonstrate that time-integrated spectra can also reproduce the low-energy spectrum of GRBs consistently using a multi-temperature effect when time evolution of the outflow is considered. Last, we show that the empirical E{sub p}-L{sub p} relation can be explained by differences in the outflow properties of individual sources.

  17. Particle multiplicity of unbiased gluon jets from $e^+ e^-$ three-jet events

    E-Print Network [OSTI]

    Abbiendi, G; Åkesson, P F; Alexander, Gideon; Allison, J; Anagnostou, G; Anderson, K J; Arcelli, S; Asai, S; Axen, D A; Azuelos, Georges; Bailey, I; Barberio, E; Barlow, R J; Batley, J Richard; Bechtle, P; Behnke, T; Bell, K W; Bell, P J; Bella, G; Bellerive, A; Benelli, G; Bethke, Siegfried; Biebel, O; Bloodworth, Ian J; Boeriu, O; Bock, P; Böhme, J; Bonacorsi, D; Boutemeur, M; Braibant, S; Brigliadori, L; Brown, R M; Burckhart, H J; Cammin, J; Campana, S; Carnegie, R K; Caron, B; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Clarke, P E L; Clay, E; Cohen, I; Couchman, J; Csilling, Akos; Cuffiani, M; Dado, S; Dallavalle, G M; Dallison, S; de Roeck, A; De Wolf, E A; Dervan, P J; Desch, Klaus; Dienes, B; Donkers, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Etzion, E; Fabbri, Franco Luigi; Feld, L; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giunta, M; Goldberg, J; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Günther, P O; Sen-Gupta, A; Hajdu, C; Hamann, M; Hanson, G G; Harder, K; Harel, A; Harin-Dirac, M; Hauschild, M; Hauschildt, J; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Hensel, C; Herten, G; Heuer, R D; Hill, J C; Hoffman, K; Homer, R James; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Ishii, K; Jawahery, A; Jeremie, H; Jones, C R; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J; Karapetian, G V; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klein, K; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Kokott, T P; Komamiya, S; Kowalewski, R V; Kramer, T; Kress, T; Krieger, P; Von Krogh, J; Krop, D; Kühl, T; Kupper, M; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lawson, I; Layter, J G; Leins, A; Lellouch, Daniel; Letts, J; Levinson, L; Lillich, J; Littlewood, C; Lloyd, S L; Loebinger, F K; Lü, J; Ludwig, J; Macchiolo, A; MacPherson, A L; Mader, W; Marcellini, S; Marchant, T E; Martin, A J; Martin, J P; Martínez, G; Masetti, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McMahon, T J; McPherson, R A; Meijers, F; Méndez-Lorenzo, P; Menges, W; Merritt, F S; Mes, H; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Moed, S; Mohr, W; Mori, T; Mutter, A; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oh, A; Okpara, A N; Oreglia, M J; Orito, S; Pahl, C; Pásztor, G; Pater, J R; Patrick, G N; Pilcher, J E; Pinfold, James L; Plane, D E; Poli, B; Polok, J; Pooth, O; Quadt, A; Rabbertz, K; Rembser, C; Renkel, P; Rick, Hartmut; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rozen, Y; Runge, K; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sarkisyan-Grinbaum, E; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Spanó, F; Sproston, M; Stahl, A; Stephens, K; Strom, D; Ströhmer, R; Stumpf, L; Surrow, B; Tarem, S; Tasevsky, M; Taylor, R J; Teuscher, R; Thomas, J; Thomson, M A; Torrence, E; Toya, D; Trefzger, T M; Tricoli, A; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Ujvári, B; Vachon, B; Vollmer, C F; Vannerem, P; Verzocchi, M; Voss, H; Vossebeld, Joost Herman; Waller, D; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wetterling, D; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Zacek, V; Zer-Zion, D; 10.1007/s100520200926

    2002-01-01T23:59:59.000Z

    The charged particle multiplicities of two- and three-jet events from the reaction e+e- -> Z0 -> hadrons are measured for Z0 decays to light quark (uds) flavors. Using recent theoretical expressions to account for biases from event selection, results corresponding to unbiased gluon jets are extracted over a range of jet energies from about 11 to 30 GeV. We find consistency between these results and direct measurements of unbiased gluon jet multiplicity from upsilon and Z0 decays. The unbiased gluon jet data including the direct measurements are compared to corresponding results for quark jets. We perform fits based on analytic expressions for particle multiplicity in jets to determine the ratio r = Ng/Nq of multiplicities between gluon and quark jets as a function of energy. We also determine the ratio of slopes, r(1) = (dNg/dy)/(dNq/dy), and of curvatures, r(2) = (d2Ng/dy2)/(d2Nq/dy2), where y specifies the energy scale. At 30 GeV, we find r = 1.422 +/- 0.051, r(1) = 1.761 +/- 0.071 and r(2) = 1.98 +/- 0.13,...

  18. Jet vetoes versus giant K-factors in the exclusive Z+1-jet cross section

    E-Print Network [OSTI]

    Boughezal, Radja; Liu, Xiaohui

    2015-01-01T23:59:59.000Z

    The ATLAS measurement of the exclusive $Z$+1-jet cross section shows a surprising agreement with fixed-order predictions in the kinematic region expected to be dominated by large jet-veto logarithms. We identify the explanation for this effect: the jet-isolation criterion implemented by ATLAS allows dijet events where an energetic jet is collinear to a final-state lepton. This process contains a giant K-factor arising from the collinear emission of a Z-boson from the dijet configuration which overwhelms the effect of the jet-veto logarithms. We provide numerical results for 7 TeV, 8 TeV and 14 TeV LHC collisions that demonstrate the interplay between the jet-veto logarithms and the giant K-factor in the theoretical prediction. We suggest an alternate isolation criterion that removes the giant K-factor and allows for a direct test of the jet-veto resummation framework in the Z+1-jet process.

  19. PERPENDICULAR ION HEATING BY REDUCED MAGNETOHYDRODYNAMIC TURBULENCE

    SciTech Connect (OSTI)

    Xia, Qian; Perez, Jean C.; Chandran, Benjamin D. G. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Quataert, Eliot, E-mail: qdy2@unh.edu, E-mail: benjamin.chandran@unh.edu, E-mail: jeanc.perez@unh.edu, E-mail: eliot@astro.berkeley.edu [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, The University of California, Berkeley, CA 94720 (United States)

    2013-10-20T23:59:59.000Z

    Recent theoretical studies argue that the rate of stochastic ion heating in low-frequency Alfvén-wave turbulence is given by Q = c{sub 1}((?u){sup 3}/?)exp (– c{sub 2}/?), where ?u is the rms turbulent velocity at the scale of the ion gyroradius ?, ? = ?u/v{sub i}, v{sub i} is the perpendicular ion thermal speed, and c{sub 1} and c{sub 2} are dimensionless constants. We test this theoretical result by numerically simulating test particles interacting with strong reduced magnetohydrodynamic (RMHD) turbulence. The heating rates in our simulations are well fit by this formula. The best-fit values of c{sub 1} are ?1. The best-fit values of c{sub 2} decrease (i.e., stochastic heating becomes more effective) as the Reynolds number and the number of grid points in the RMHD simulations increase. As an example, in a 1024{sup 2} × 256 RMHD simulation with a dissipation wavenumber of the order of the inverse ion gyroradius, we find c{sub 2} = 0.21. We show that stochastic heating is significantly stronger in strong RMHD turbulence than in a field of randomly phased Alfvén waves with the same power spectrum, because coherent structures in strong RMHD turbulence increase orbit stochasticity in the regions where ions are heated most strongly. We find that c{sub 1} increases by a factor of ?3 while c{sub 2} changes very little as the ion thermal speed increases from values <

  20. Stability of prograde and retrograde planets in circular binary systems

    E-Print Network [OSTI]

    M. H. M. Morais; C. A. Giuppone

    2012-06-22T23:59:59.000Z

    We investigate the stability of prograde versus retrograde planets in circular binary systems using numerical simulations. We show that retrograde planets are stable up to distances closer to the perturber than prograde planets. We develop an analytical model to compute the prograde and retrograde mean motion resonances' locations and separatrices. We show that instability is due to single resonance forcing, or caused by nearby resonances' overlap. We validate our results regarding the role of single resonances and resonances' overlap on orbit stability, by computing surfaces of section of the CR3BP. We conclude that the observed enhanced stability of retrograde planets with respect to prograde planets is due to essential differences between the phase-space topology of retrograde versus prograde resonances (at p/q mean motion ratio, prograde resonance is of order p - q while retrograde resonance is of order p + q).

  1. Large-amplitude circularly polarized electromagnetic waves in magnetized plasma

    SciTech Connect (OSTI)

    Vasko, I. Y., E-mail: vaskoiy@gmail.com; Artemyev, A. V.; Zelenyi, L. M. [Space Research Institute, RAS, Moscow (Russian Federation)] [Space Research Institute, RAS, Moscow (Russian Federation)

    2014-05-15T23:59:59.000Z

    We consider large-amplitude circularly polarized (LACP) waves propagating in a magnetized plasma. It is well-known that the dispersion relation for such waves coincides with the dispersion relation given by the linear theory. We develop the model of LACP wave containing a finite population of Cerenkov resonant particles. We find that the current of resonant particles modifies the linear dispersion relation. Dispersion curves of low-frequency (i.e., whistler and magnetosonic) waves are shifted toward larger values of the wave vector, i.e., waves with arbitrarily large wavelengths do not exist in this case. Dispersion curves of high-frequency waves are modified so that the wave phase velocity becomes smaller than the speed of light.

  2. Energy spectra of two electrons in a circular quantum dot

    E-Print Network [OSTI]

    Anjana Sinha; Y. P. Varshni

    2002-08-27T23:59:59.000Z

    The electron interaction energy of two interacting electrons in a circular quantum dot (with hard wall confinement) is investigated in the framework of the semi-classical Wentzel-Kramers-Brillouin (WKB) approximation. The two electrons are assumed to be in an infinitely deep well of radius $r_0$, in a simple configuration with one electron fixed at the origin. The corresponding Schrodinger equation, with hard wall boundary conditions, is also solved exactly by numerical integration. It is observed that the agreement between the two energy values is quite good, suggesting that the WKB approximation works well for such a confined quantum system as well. This may provide motivation to extend this to more realistic confined potentials.

  3. Annular gap solitons in Kerr media with circular gratings

    SciTech Connect (OSTI)

    Scheuer, Jacob [School of Electrical Engineering, Tel-Aviv University, Tel Aviv 69978 (Israel); Center for Nanoscience and Nanotechnology, Tel-Aviv University, Tel Aviv 69978 (Israel); Malomed, Boris [School of Electrical Engineering, Tel-Aviv University, Tel Aviv 69978 (Israel)

    2007-06-15T23:59:59.000Z

    We introduce standing-light patterns trapped in a Bragg grating written along the radial direction in a self-focusing (SF) or self-defocusing (SDF) optical medium. Unlike previously studied axisymmetric settings that deal with the axial propagation, we consider the propagation of light in the radial directions (outward and inward), which may give rise to annular gap solitons (AGSs), supported by the circular grating. An estimate for the threshold of the modulational instability of the AGS against azimuthal perturbations in the SF medium is obtained analytically, and verified by direct simulations. In the SDF model, stable annular and dipole solitons are found in a numerical form, while multipole patterns and vortex rings are unstable. Similar solitons are possible in the Bose-Einstein condensate.

  4. Protein Characterisation by Synchrotron Radiation Circular Dichroism (SRCD) Spectroscopy

    SciTech Connect (OSTI)

    Wallace, B.

    2009-01-01T23:59:59.000Z

    Circular dichroism (CD) spectroscopy is a well-established technique for the study of proteins. Synchrotron radiation circular dichroism (SRCD) spectroscopy extends the utility of conventional CD spectroscopy (i.e. using laboratory-based instruments) because the high light flux from a synchrotron enables collection of data to lower wavelengths, detection of spectra with higher signal-to-noise levels and measurements in the presence of strongly absorbing non-chiral components such as salts, buffers, lipids and detergents. This review describes developments in instrumentation, methodologies and bioinformatics that have enabled new applications of the SRCD technique for the study of proteins. It includes examples of the use of SRCD spectroscopy for providing static and dynamic structural information on molecules, including determinations of secondary structures of intact proteins and domains, assessment of protein stability, detection of conformational changes associated with ligand and drug binding, monitoring of environmental effects, examination of the processes of protein folding and membrane insertion, comparisons of mutant and modified proteins, identification of intermolecular interactions and complex formation, determination of the dispositions of proteins in membranes, identification of natively disordered proteins and their binding partners and examination of the carbohydrate components of glycoproteins. It also discusses how SRCD can be used in conjunction with macromolecular crystallography and other biophysical techniques to provide a more complete picture of protein structures and functions, including how proteins interact with other macromolecules and ligands. This review also includes a discussion of potential new applications in structural and functional genomics using SRCD spectroscopy and future instrumentation and bioinformatics developments that will enable such studies. Finally, the appendix describes a number of computational/bioinformatics resources for secondary structure analyses that take advantage of the improved data quality available from SRCD. In summary, this review discusses how SRCD can be used for a wide range of structural and functional studies of proteins.

  5. MULTIWAVELENGTH OBSERVATIONS OF THE SS 433 JETS

    SciTech Connect (OSTI)

    Marshall, Herman L.; Canizares, Claude R.; Schulz, Norbert S.; Nowak, Michael [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Hillwig, Todd [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States); Mioduszewski, Amy; Rupen, Michael [NRAO, P.O. Box 2, Socorro, NM 87801 (United States); Heinz, Sebastian, E-mail: hermanm@space.mit.edu, E-mail: crc@space.mit.edu, E-mail: nss@space.mit.edu, E-mail: mnowak@space.mit.edu, E-mail: todd.hillwig@valpo.edu, E-mail: amiodusz@nrao.edu, E-mail: mrupen@aoc.nrao.edu, E-mail: heinzs@astro.wisc.edu [Astronomy Department, 5408 Sterling Hall, University of Wisconsin, Madison, WI 53706 (United States)

    2013-09-20T23:59:59.000Z

    We present observations of the SS 433 jets using the Chandra High Energy Transmission Grating Spectrometer with contemporaneous optical and Very Long Baseline Array observations. The X-ray and optical emission line regions are found to be related but not coincident as the optical line emission persists for days while the X-ray emission lines fade in less than 5000 s. The line Doppler shifts from the optical and X-ray lines match well, indicating that they are less than 3 × 10{sup 14} cm apart. The jet Doppler shifts show aperiodic variations that could result from shocks in interactions with the local environment. These perturbations are consistent with a change in jet direction but not jet speed. The proper motions of the radio knots match the kinematic model only if the distance to SS 433 is 4.5 ± 0.2 kpc. Observations during eclipse show that the occulted emission is very hard, seen only above 2 keV and rising to comprise >50% of the flux at 8 keV. The soft X-ray emission lines from the jet are not blocked, constraining the jet length to ?> 2 × 10{sup 12} cm. The base jet density is in the range 10{sup 10-13} cm{sup –3}, in contrast to our previous estimate based on the Si XIII triplet, which is likely to have been affected by UV de-excitation. There is a clear overabundance of Ni by a factor of about 15 relative to the solar value, which may have resulted from an unusual supernova that formed the compact object.

  6. PHYSICAL REVIEW B 84, 144511 (2011) Rectification of vortex motion in a circular ratchet channel

    E-Print Network [OSTI]

    Plourde, Britton L. T.

    2011-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 84, 144511 (2011) Rectification of vortex motion in a circular ratchet channel N and induces a net vortex flow without any unbiased external drive, i.e., the ratchet effect. We show containing a single weak-pinning circular ratchet channel in a Corbino geometry and observed a substantial

  7. Evaluation of Circular-Shaped Features on the Surface of Solar Cells from the

    E-Print Network [OSTI]

    to earth, while the other one was jettisoned. Two solar panel assemblies of the retrieved wing wereEvaluation of Circular-Shaped Features on the Surface of Solar Cells from the Hubble Space by the manufacturer of the CMX coverglass of the HST solar cells, circular shaped features of unknown origin were

  8. Cyclic Testing of Concrete-Filled Circular Steel Bridge Piers having Encased Fixed-Based Detail

    E-Print Network [OSTI]

    Bruneau, Michel

    Cyclic Testing of Concrete-Filled Circular Steel Bridge Piers having Encased Fixed-Based Detail elements during earthquakes, this paper reports on cyclic inelastic tests executed to determine the maximum strength and ductility of four concrete-filled circular steel piers joined to a foundation detail proposed

  9. Is the Long-Term Persistency of Circular Polarisation due to the Constant Helicity of the Magnetic Fields in Rotating Quasar Engines?

    E-Print Network [OSTI]

    Torsten A. Ensslin

    2003-05-09T23:59:59.000Z

    Many compact radio sources like quasars, blazars, radio galaxies, and micro-quasars emit circular polarisation (CP) with surprising temporal persistent handedness. We propose that the CP is caused by Faraday conversion of linear polarisation synchrotron light which propagates along a line-of-sight through helical magnetic fields. Jet outflows from radio galaxies should have the required magnetic helicity in the emission region due to the magnetic torque of the accretion disc. Also advection dominated accretion flow (ADAF) should contain magnetic fields with the same helicity. However, a jet region seems to be the more plausible origin of CP. The proposed scenario requires Faraday rotation (FR) to be insignificant in the emission region. The proposed mechanism works in electron-positron e+/e- as well as electron-proton e/p plasma. In the latter case, the emission region should consist of individual flux tubes with independent polarities in order to suppress too strong FR - as it was already proposed for FR based CP generation models. The predominant CP is expected to mostly counter-rotate (rotation is measured here in sky-projection) with respect to the central engine in all cases (jet or ADAF, e+/e- or e/p plasma) and therefore allows to measure the sense of rotation of quasar engines. The engine of SgrA* is expected - in this scenario - to rotate clockwise and therefore counter-Galactic, as do the young hot stars in its vicinity, which are thought to feed SgrA* by their winds. Generally, sources with Stokes-V0) are expected to rotate clockwise

  10. E-Print Network 3.0 - african easterly jet Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    EasterlyEasterly Jet (AEJ) :Jet (AEJ) : Vent thermique d'Est principalement li ... Nord lors de la priode de mousson. TropicalTropical EasterlyEasterly Jet (TEJ) :Jet (TEJ)...

  11. A Study of Vertical Gas Jets in a Bubbling Fluidized Bed

    SciTech Connect (OSTI)

    Steven Ceccio; Jennifer Curtis

    2011-01-18T23:59:59.000Z

    A detailed experimental study of a vertical gas jet impinging a fluidized bed of particles has been conducted with the help of Laser Doppler Velocimetry measurements. Mean and fluctuating velocity profiles of the two phases have been presented and analyzed for different fluidization states of the emulsion. The results of this work would be greatly helpful in understanding the complex two-phase mixing phenomenon that occurs in bubbling beds, such as in coal and biomass gasification, and also in building more fundamental gas-solid Eulerian/Lagrangian models which can be incorporated into existing CFD codes. Relevant simulations to supplement the experimental findings have also been conducted using the Department of Energyâ??s open source code MFIX. The goal of these simulations was two-fold. One was to check the two-dimensional nature of the experimental results. The other was an attempt to improve the existing dense phase Eulerian framework through validation with the experimental results. In particular the sensitivity of existing frictional models in predicting the flow was investigated. The simulation results provide insight on wall-bounded turbulent jets and the effect frictional models have on gas-solid bubbling flows. Additionally, some empirical minimum fluidization correlations were validated for non-spherical particles with the idea of extending the present study to non-spherical particles which are more common in industries.

  12. A study of the self-oscillating jet impingement nozzle

    E-Print Network [OSTI]

    Chinnock, Paul Scott

    1993-01-01T23:59:59.000Z

    wave and flow fluctuations that need no external input. The new oscillating jet when used for impingement surface transport was labeled the Self-Oscillating Jet Impingement Nozzle. The objectives of this research were to characterize the gains in heat...

  13. Applications of Underexpanded Jets in Hypersonic Aerothermodynamics Research

    E-Print Network [OSTI]

    Riabov, Vladimir V.

    Applications of Underexpanded Jets in Hypersonic Aerothermodynamics Research Vladimir V. Riabov Abstract. A method of underexpanded hypersonic viscous jets has been developed to acquire experimental parameters are revealed. In the case of hypersonic stabilization, the Reynolds number and temperature factor

  14. Feedback control of flow separation using synthetic jets

    E-Print Network [OSTI]

    Kim, Kihwan

    2006-04-12T23:59:59.000Z

    The primary goal of this research is to assess the effect of synthetic jets on flow separation and provide a feedback control strategy for flow separation using synthetic jets. The feedback control synthesis is conducted based upon CFD simulation...

  15. Images in Emergency Medicine: Irritant Contact Dermatitis from Jet Fuel

    E-Print Network [OSTI]

    Trigger, Christopher C; Eilbert, Wesley

    2009-01-01T23:59:59.000Z

    and penetration of JP-8 jet fuel and its components. Toxicoland other kerosene-based fuels have been shown to cause skinContact Dermatitis from Jet Fuel Christopher C. Trigger, MD

  16. Active noise control of supersonic impinging jet using pulsed microjets

    E-Print Network [OSTI]

    Hong, Seung Hyuck

    2009-01-01T23:59:59.000Z

    This thesis concerns an active noise control of supersonic impinging jet flow using unsteady microjet injection. Supersonic impinging jet involves several problems such as lift loss, ground erosion, significant noise ...

  17. Use Steam Jet Ejectors or Thermocompressors to Reduce Venting...

    Broader source: Energy.gov (indexed) [DOE]

    Steam Jet Ejectors or Thermocompressors to Reduce Venting of Low-Pressure Steam Use Steam Jet Ejectors or Thermocompressors to Reduce Venting of Low-Pressure Steam This tip sheet...

  18. Mixing enhancement by use of swirling jets

    SciTech Connect (OSTI)

    Kraus, D.K.; Cutler, A.D.

    1993-01-01T23:59:59.000Z

    It has been proposed that the mixing of fuel with air in the combustor of scramjet engines might be enhanced by the addition of swirl to the fuel jet prior to injection. This study investigated the effects of swirl on the mixing of a 30 deg wall jet into a Mach 2 flow. Cases with swirl and without swirl were investigated, with both helium and air simulating the fuel. Rayleigh scattering was used to visualize the flow, and seeding the fuel with water allowed it to be traced through the main flow. The results show that the addition of swirl to the fuel jet causes the fuel to mix more rapidly with the main flow, that larger amounts of swirl increase this effect, and that helium spreads better into the main flow than air. 12 refs.

  19. Extragalactic jets on subpc and large scales

    E-Print Network [OSTI]

    F. Tavecchio

    2007-08-20T23:59:59.000Z

    Jets can be probed in their innermost regions (d~0.1 pc) through the study of the relativistically-boosted emission of blazars. On the other extreme of spatial scales, the study of structure and dynamics of extragalactic relativistic jets received renewed impulse after the discovery, made by Chandra, of bright X-ray emission from regions at distances larger than hundreds of kpc from the central engine. At both scales it is thus possible to infer some of the basic parameters of the flow (speed, density, magnetic field intensity, power). After a brief review of the available observational evidence, I discuss how the comparison between the physical quantities independently derived at the two scales can be used to shed light on the global dynamics of the jet, from the innermost regions to the hundreds of kpc scale.

  20. On the Misalignment of Jets in Microquasars

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2002-09-05T23:59:59.000Z

    We discuss the timescales for alignment of black hole and accretion disc spins in the context of binary systems. We show that for black holes that are formed with substantial angular momentum, the alignment timescales are likely to be at least a substantial fraction of the systems' lifetimes. This result explains the observed misalignment of the disc and the jet in the microquasar GRO J 1655-40 and in SAX J 1819-2525 as being likely due to the Bardeen-Petterson effect. We discuss the implications of these results on the mass estimate for GRS 1915+105, which has assumed the jet is perpendicular to the orbital plane of the system and may hence be an underestimate. We show that the timescales for the spin alignment in Cygnus X-3 are consistent with the likely misalignment of disc and jet in that system, and that this is suggested by the observational data.

  1. Refined Critical Balance in Strong Alfvénic Turbulence

    E-Print Network [OSTI]

    A. Mallet; A. A. Schekochihin; B. D. G. Chandran

    2014-06-21T23:59:59.000Z

    We present numerical evidence that in strong Alfv\\'enic turbulence, the critical balance principle---equality of the nonlinear decorrelation and linear propagation times---is scale invariant, in the sense that the probability distribution of the ratio of these times is independent of scale. This result only holds if the local alignment of the Elsasser fields is taken into account in calculating the nonlinear time. At any given scale, the degree of alignment is found to increase with fluctuation amplitude, supporting the idea that the cause of alignment is mutual dynamical shearing of Elsasser fields. The scale-invariance of critical balance (while all other quantities of interest are strongly intermittent, i.e., have scale-dependent distributions) suggests that it is the most robust of the scaling principles used to describe Alfv\\'enic turbulence.

  2. Generalized Batchelor functions of isotropic turbulence

    E-Print Network [OSTI]

    Gravanis, Elias

    2015-01-01T23:59:59.000Z

    We generalize Batchelor's parameterization of the autocorrelation functions of isotropic turbulence in a form involving a product expansion with multiple small scales. The richer small scale structure acquired this way, compared to the usual Batchelor function, is necessary so that the associated energy spectrum approximate well actual spectra in the universal equilibrium range. We propose that the generalized function provides an approximation of arbitrary accuracy for actual spectra of isotropic turbulence over the universal equilibrium range. The degree of accuracy depends on the number of higher moments which are determinable and it is reflected in the number of small scales involved. The energy spectrum of the generalized function is derived, and for the case of two small scales is compared with data from high-resolution direct numerical simulations. We show that the compensated spectra (which illustrate the bottleneck effect) and dissipation spectra are encapsulated excellently, in accordance with our p...

  3. PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY

    E-Print Network [OSTI]

    Christian, Eric

    , velocity and turbulence of the solar atmosphere. Dr. Michael Bird of the University of Bonn, Germany from Ulysses will pass close to the sun's surface and travel through the dense lower solar atmosphere," Page said. At closest approach, the signals will cross through 1 #12;the sun's corona at four solar

  4. QCD Jet Rates with the Inclusive Generalized kt Algorithms

    E-Print Network [OSTI]

    Erik Gerwick; Ben Gripaios; Steffen Schumann; Bryan Webber

    2013-04-15T23:59:59.000Z

    We derive generating functions, valid to next-to-double logarithmic accuracy, for QCD jet rates according to the inclusive forms of the kt, Cambridge/Aachen and anti-kt algorithms, which are equivalent at this level of accuracy. We compare the analytical results with jet rates and average jet multiplicities from the SHERPA event generator, and study the transition between Poisson-like and staircase-like behaviour of jet ratios.

  5. On the Counter-jet Emission in GRB Afterglows

    SciTech Connect (OSTI)

    Wang Xin; Huang, Y. F. [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2010-10-15T23:59:59.000Z

    We investigate the dynamical evolution of double-sided jets and present detailed numerical studies on the emission from the receding jet of gamma-ray bursts. It is found that the receding jet emission is generally very weak and only manifests as a plateau in the late time radio afterglow light curves. Additionally, we find that the effect of synchrotron self-absorption can influence the peak time of the receding jet emission significantly.

  6. Gauge/gravity duality and jets in strongly coupled plasma

    E-Print Network [OSTI]

    Paul M. Chesler

    2009-10-08T23:59:59.000Z

    We discuss jets in strongly coupled N = 4 supersymmetric Yang-Mills plasma and their dual gravitational description.

  7. NONIDEAL MAGNETOHYDRODYNAMIC TURBULENT DECAY IN MOLECULAR CLOUDS

    SciTech Connect (OSTI)

    Downes, T. P. [School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); O'Sullivan, S. [National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)], E-mail: turlough.downes@dcu.ie

    2009-08-20T23:59:59.000Z

    It is well known that nonideal magnetohydrodynamic (MHD) effects are important in the dynamics of molecular clouds: both ambipolar diffusion and possibly the Hall effect have been identified as significant. We present the results of a suite of simulations with a resolution of 512{sup 3} of turbulent decay in molecular clouds, incorporating a simplified form of both ambipolar diffusion and the Hall effect simultaneously. The initial velocity field in the turbulence is varied from being super-Alfvenic and hypersonic, through to trans-Alfvenic but still supersonic. We find that ambipolar diffusion increases the rate of decay of the turbulence increasing the decay from t {sup -1.25} to t {sup -1.4}. The Hall effect has virtually no impact in this regard. The power spectra of density, velocity, and the magnetic field are all affected by the nonideal terms, being steepened significantly when compared with ideal MHD turbulence with exponents. The density power-spectra components change from {approx}1.4 to {approx}2.1 for the ideal and nonideal simulations respectively, and power spectra of the other variables all show similar modifications when nonideal effects are considered. Again, the dominant source of these changes is ambipolar diffusion rather than the Hall effect. There is also a decoupling between the velocity field and the magnetic field at short length scales. The Hall effect leads to enhanced magnetic reconnection, and hence less power, at short length scales. The dependence of the velocity dispersion on the characteristic length scale is studied and found not to be power law in nature.

  8. Acceleration and vortex filaments in turbulence

    E-Print Network [OSTI]

    F. Toschi; L. Biferale; G. Boffetta; A. Celani; B. J. Devenish; A. Lanotte

    2005-01-23T23:59:59.000Z

    We report recent results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov time-scale up to one large-eddy turnover time. We present some results concerning acceleration statistics and the statistics of trapping by vortex filaments.

  9. Universal constants and equations of turbulent motion

    E-Print Network [OSTI]

    Helmut Z. Baumert

    2011-07-25T23:59:59.000Z

    In the spirit of Prandtl's conjecture of 1926, for turbulence at high Reynolds number we present an analogy with the kinetic theory of gases, with dipoles made of quasi-rigid and 'dressed' vortex tubes as frictionless, incompressible but deformable quasi-particles. Their movements are governed by Helmholtz' elementary vortex rules applied locally. A contact interaction or 'collision' leads either to random scatter of a trajectory or to the formation of two likewise rotating, fundamentally unstable whirls forming a dissipative patch slowly rotating around its center of mass which is almost at rest. This approach predicts von Karman's constant as 1/sqrt(2 pi) = 0.399 and the spatio-temporal dynamics of energy-containing time and length scales controlling turbulent mixing [Baumert 2009]. A link to turbulence spectra was missing so far. In the present paper it is shown that the above image of random vortex-dipole movements is compatible with Kolmogorov's turbulence spectra if dissipative patches, beginning as two likewise rotating eddies, evolve locally into a space-filling bearing in the sense of Herrmann [1990], i.e. into an "Apollonian gear". Its parts and pieces are incompressible and flexibly deformable vortex tubes which are frictionless, excepting the dissipative scale of size zero. For steady and locally homogeneous conditions our approach predicts the dimensionless pre-factor in the 3D Eulerian wavenumber spectrum as [(4 pi)^2/3]/3 = 1.8, and in the Lagrangian frequency spectrum as 2. Our derivations rest on geometry, methods from many-particle physics, and on elementary conservation laws.

  10. Free energy balance in gyrokinetic turbulence

    SciTech Connect (OSTI)

    Banon Navarro, A.; Morel, P.; Albrecht-Marc, M.; Carati, D. [Statistical and Plasma Physics Laboratory, Universite Libre de Bruxelles (Belgium); Merz, F.; Goerler, T.; Jenko, F. [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

    2011-09-15T23:59:59.000Z

    Free energy plays an important role in gyrokinetic theory, since it is known to be a nonlinear invariant. Its evolution equations are derived and analyzed for the case of ion temperature gradient driven turbulence, using the formalism adopted in the Gene code. In particular, the ion temperature gradient drive, the collisional dissipation as well as entropy/electrostatic energy transfer channels represented by linear curvature and parallel terms are analyzed in detail.

  11. THE HELICAL JET OF THE VELA PULSAR

    SciTech Connect (OSTI)

    Durant, Martin; Kargaltsev, Oleg [University of Florida, 211 Bryant Space Science Center, Gainesville, FL (United States)] [University of Florida, 211 Bryant Space Science Center, Gainesville, FL (United States); Pavlov, George G. [Pennsylvania State University, 525 Davey Lab, University Park, PA (United States)] [Pennsylvania State University, 525 Davey Lab, University Park, PA (United States); Kropotina, Julia; Levenfish, Kseniya, E-mail: mdurant@sri.utoronto.ca [St.-Petersburg State Polytechnical University, Polytekhnicheskaya ul. 29, St.-Petersburg, 195251 (Russian Federation)] [St.-Petersburg State Polytechnical University, Polytekhnicheskaya ul. 29, St.-Petersburg, 195251 (Russian Federation)

    2013-02-15T23:59:59.000Z

    We have studied the fascinating dynamics of the nearby Vela pulsar's nebula in a campaign comprising 11 40 ks observations with the Chandra X-Ray Observatory. The deepest images yet revealed the shape, structure, and motion of the 2 arcmin long pulsar jet. We find that the jet's shape and dynamics are remarkably consistent with those of a steadily turning helix projected on the sky. We discuss possible implications of our results, including free precession of the neutron star and MHD instability scenarios.

  12. Gamma-Ray Bursts: Jets and Energetics

    E-Print Network [OSTI]

    D. A. Frail

    2003-11-12T23:59:59.000Z

    The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.

  13. Enhancement of wall jet transport properties

    DOE Patents [OSTI]

    Claunch, S.D.; Farrington, R.B.

    1997-02-04T23:59:59.000Z

    By enhancing the natural instabilities in the boundary layer and in the free shear layer of a wall jet, the boundary is minimized thereby increasing the transport of heat and mass. Enhancing the natural instabilities is accomplished by pulsing the flow of air that creates the wall jet. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct. 17 figs.

  14. High pressure water jet mining machine

    DOE Patents [OSTI]

    Barker, Clark R. (Rolla, MO)

    1981-05-05T23:59:59.000Z

    A high pressure water jet mining machine for the longwall mining of coal is described. The machine is generally in the shape of a plowshare and is advanced in the direction in which the coal is cut. The machine has mounted thereon a plurality of nozzle modules each containing a high pressure water jet nozzle disposed to oscillate in a particular plane. The nozzle modules are oriented to cut in vertical and horizontal planes on the leading edge of the machine and the coal so cut is cleaved off by the wedge-shaped body.

  15. On specification of initial conditions in turbulence models

    SciTech Connect (OSTI)

    Rollin, Bertrand [Los Alamos National Laboratory; Andrews, Malcolm J [Los Alamos National Laboratory

    2010-12-01T23:59:59.000Z

    Recent research has shown that initial conditions have a significant influence on the evolution of a flow towards turbulence. This important finding offers a unique opportunity for turbulence control, but also raises the question of how to properly specify initial conditions in turbulence models. We study this problem in the context of the Rayleigh-Taylor instability. The Rayleigh-Taylor instability is an interfacial fluid instability that leads to turbulence and turbulent mixing. It occurs when a light fluid is accelerated in to a heavy fluid because of misalignment between density and pressure gradients. The Rayleigh-Taylor instability plays a key role in a wide variety of natural and man-made flows ranging from supernovae to the implosion phase of Inertial Confinement Fusion (ICF). Our approach consists of providing the turbulence models with a predicted profile of its key variables at the appropriate time in accordance to the initial conditions of the problem.

  16. Forecasting Turbulent Modes with Nonparametric Diffusion Models

    E-Print Network [OSTI]

    Tyrus Berry; John Harlim

    2015-01-27T23:59:59.000Z

    This paper presents a nonparametric diffusion modeling approach for forecasting partially observed noisy turbulent modes. The proposed forecast model uses a basis of smooth functions (constructed with the diffusion maps algorithm) to represent probability densities, so that the forecast model becomes a linear map in this basis. We estimate this linear map by exploiting a previously established rigorous connection between the discrete time shift map and the semi-group solution associated to the backward Kolmogorov equation. In order to smooth the noisy data, we apply diffusion maps to a delay embedding of the noisy data, which also helps to account for the interactions between the observed and unobserved modes. We show that this delay embedding biases the geometry of the data in a way which extracts the most predictable component of the dynamics. The resulting model approximates the semigroup solutions of the generator of the underlying dynamics in the limit of large data and in the observation noise limit. We will show numerical examples on a wide-range of well-studied turbulent modes, including the Fourier modes of the energy conserving Truncated Burgers-Hopf (TBH) model, the Lorenz-96 model in weakly chaotic to fully turbulent regimes, and the barotropic modes of a quasi-geostrophic model with baroclinic instabilities. In these examples, forecasting skills of the nonparametric diffusion model are compared to a wide-range of stochastic parametric modeling approaches, which account for the nonlinear interactions between the observed and unobserved modes with white and colored noises.

  17. Phenomenology of Wall Bounded Newtonian Turbulence

    E-Print Network [OSTI]

    Victor S. L'vov; Anna Pomyalov; Itamar Procaccia; Sergej S. Zilitinkevich

    2005-06-28T23:59:59.000Z

    We construct a simple analytic model for wall-bounded turbulence, containing only four adjustable parameters. Two of these parameters characterize the viscous dissipation of the components of the Reynolds stress-tensor and other two parameters characterize their nonlinear relaxation. The model offers an analytic description of the profiles of the mean velocity and the correlation functions of velocity fluctuations in the entire boundary region, from the viscous sub-layer, through the buffer layer and further into the log-layer. As a first approximation, we employ the traditional return-to-isotropy hypothesis, which yields a very simple distribution of the turbulent kinetic energy between the velocity components in the log-layer: the streamwise component contains a half of the total energy whereas the wall-normal and the cross-stream components contain a quarter each. In addition, the model predicts a very simple relation between the von-K\\'arm\\'an slope $\\kappa $ and the turbulent velocity in the log-law region $v^+$ (in wall units): $v^+=6 \\kappa$. These predictions are in excellent agreement with DNS data and with recent laboratory experiments.

  18. Universal equations and constants of turbulent motion

    E-Print Network [OSTI]

    Helmut Z. Baumert

    2012-03-22T23:59:59.000Z

    This paper presents a parameter-free theory of shear-generated turbulence at asymptotically high Reynolds numbers in incompressible fluids. It is based on a two-fluids concept. Both components are materially identical and inviscid. The first component is an ensemble of quasi-rigid dipole-vortex tubes as quasi-particles in chaotic motion. The second is a superfluid performing evasive motions between the tubes. The local dipole motions follow Helmholtz' law. The vortex radii scale with the energy-containing length scale. Collisions between quasi-particles lead either to annihilation (likewise rotation, turbulent dissipation) or to scattering (counterrotation, turbulent diffusion). There are analogies with birth and death processes of population dynamics and their master equations. For free homogeneous decay the theory predicts the TKE to follow 1/t. With an adiabatic condition at the wall it predicts the logarithmic law with von Karman's constant as 1/\\sqrt{2 pi} = 0.399. Likewise rotating couples form dissipative patches almost at rest ($\\rightarrow$ intermittency) wherein the spectrum evolves like an "Apollonian gear" as discussed first by Herrmann, 1990. On this basis the prefactor of the 3D-wavenumber spectrum is predicted as (1/3)(4 pi)^{2/3}=1.8; in the Lagrangian frequency spectrum it is simply 2. The results are situated well within the scatter range of observational, experimental and DNS results.

  19. Continuous representation for shell models of turbulence

    E-Print Network [OSTI]

    Alexei A. Mailybaev

    2014-09-16T23:59:59.000Z

    In this work we construct and analyze continuous hydrodynamic models in one space dimension, which are induced by shell models of turbulence. After Fourier transformation, such continuous models split into an infinite number of uncoupled subsystems, which are all identical to the same shell model. The two shell models, which allow such a construction, are considered: the dyadic (Desnyansky--Novikov) model with the intershell ratio $\\lambda = 2^{3/2}$ and the Sabra model of turbulence with $\\lambda = \\sqrt{2+\\sqrt{5}} \\approx 2.058$. The continuous models allow understanding various properties of shell model solutions and provide their interpretation in physical space. We show that the asymptotic solutions of the dyadic model with Kolmogorov scaling correspond to the shocks (discontinuities) for the induced continuous solutions in physical space, and the finite-time blowup together with its viscous regularization follow the scenario similar to the Burgers equation. For the Sabra model, we provide the physical space representation for blowup solutions and intermittent turbulent dynamics.

  20. Fusion Rules in Turbulent Systems with Flux Equilibrium

    E-Print Network [OSTI]

    Victor L'vov; Itamar Procaccia

    1995-07-27T23:59:59.000Z

    Fusion rules in turbulence specify the analytic structure of many-point correlation functions of the turbulent field when a group of coordinates coalesce. We show that the existence of flux equilibrium in fully developed turbulent systems combined with a direct cascade induces universal fusion rules. In certain examples these fusion rules suffice to compute the multiscaling exponents exactly, and in other examples they give rise to an infinite number of scaling relations that constrain enormously the structure of the allowed theory.

  1. X-ray magnetic circular dichroism in (Ge,Mn) compounds: experiments and modeling Samuel Tardif,1, 2,

    E-Print Network [OSTI]

    X-ray magnetic circular dichroism in (Ge,Mn) compounds: experiments and modeling Samuel Tardif,1, 2: July 29, 2013) X-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra at the L2),6 and x-ray spectroscopy (x-ray absorption spec- troscopy, XAS, and x-ray magnetic circular

  2. Massively Parallel Spectral Element Large Eddy Simulation of a Turbulent Channel Using Wall Models

    E-Print Network [OSTI]

    Rabau, Joshua I

    2013-05-01T23:59:59.000Z

    Wall-bounded turbulent flows are prevalent in engineering and industrial applications. Walls greatly affect turbulent characteristics in many ways including production and propagation of turbulent stresses. While computational fluid dynamics can...

  3. Studying Z/gamma*+Jet Production

    SciTech Connect (OSTI)

    Nilsen, Henrik Wold; /Freiburg U.

    2009-07-01T23:59:59.000Z

    The production of jets in association with a Z/{gamma}* boson is an example of an important class of processes at hadron colliders, namely vector boson + jet (V + jet) production. Comparisons of measurements of this class of processes with theory predictions constitute an important, fundamental test of the Standard Model of particle physics, and of the theory of QCD in particular. While having a smaller cross section than other V +jet processes, Z/{gamma}*({yields} e{sup +}e{sup -}) + jets production, with Z/{gamma}* {yields} e{sup +}e{sup -}/{mu}{sup +}{mu}{sup -}, has a distinct experimental signature allowing for measurements characterized by low backgrounds and a direct, precise measurement of the properties of the decay products of the Z/{gamma}* boson. In this thesis, several new measurements of the properties of jets produced in association with a Z/{gamma}* boson in p{bar p} collisions at {radical}s = 1.96 TeV are presented. The cross section for Z/{gamma}*({yields} e{sup +}e{sup -}) + N jet production (N {le} 3) is measured, differential in the transverse momentum of the Nth jet in the event, normalized to the inclusive Z/{gamma}* cross section. Also, the cross section for Z/{gamma}*({yields} e{sup +}e{sup -}) + N jets (N {ge} 1) is measured, differential in the difference in azimuthal angle between the di-electron system and any jet in the event, normalized to unity. The data used in the measurements were collected by the D0 experiment located at the Tevatron Collider of the Fermi National Accelerator Laboratory and correspond to an integrated luminosity of 1.04 fb{sup -1}. The measured jet transverse momentum spectra are compared with the predictions of perturbative calculations at the next-to-leading order in the strong coupling constant. Given the low sensitivity of the calculations to model parameters, these comparisons represent a stringent test of perturbative QCD. One of the main goals currently being pursued in particle physics is the discovery of the only particle predicted by the Standard Model which has so far no been detected experimentally, namely the Higgs boson. It is assumed that the ATLAS and CMS experiments located at the Large Hadron Collider (LHC), a proton-proton collider at {radical}s = 14 TeV, will be able to detect the Higgs boson, or rule out its existence, within the next few years. The collisions delivered by the LHC will also be used to perform a long range of searches for other new particles, for instance particles predicted by models based on the principle of supersymmetry. The associated production of vector bosons with jets has relatively large production rates at the LHC and can produce a long list of different final states which can include charged leptons, missing transverse energy, as well as light- and heavy-flavour jets. This makes V + jet production a major source of background events to many searches for new particles. Most techniques used for estimating the expected number of background events to searches rely on passing the stable final-state particles of simulated hadron collisions generated using a so-called event generator code, through a simulation of the experimental detector system. The development of event generators which are capable of reliably predicting the properties of jets produced in association with a core process, e.g. the production of a vector boson, has been the subject of a large amount of research activity during the last ten years. These efforts have led to the appearance of the CKKW and MLM algorithms which are implemented in several event generators, among them SHERPA and ALPGEN + PYTHIA. The large data sample collected by the D0 experiment during Run II offers an excellent opportunity for validating these new event generators against experimental measurements of V + jet production. As argued above, the Z/{gamma}*({yields} e{sup +}e{sup -}) + jets process offers the combination of a clean experimental signature and large production rates, making it the process of choice for these studies.

  4. Generation of circularly polarized radiation from a compact plasma-based extreme ultraviolet light source for tabletop X-ray magnetic circular dichroism studies

    SciTech Connect (OSTI)

    Wilson, Daniel; Rudolf, Denis, E-mail: d.rudolf@fz-juelich.de; Juschkin, Larissa [RWTH Aachen University, Experimental Physics of EUV, Steinbachstraße 15, 52074 Aachen (Germany); Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany); Weier, Christian; Adam, Roman; Schneider, Claus M. [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), JARA-FIT, 52425 Jülich (Germany); Winkler, Gerrit; Frömter, Robert [Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); Danylyuk, Serhiy [RWTH Aachen University, Chair for Technology of Optical Systems, JARA-FIT, Steinbachstraße 15, 52074 Aachen (Germany); Bergmann, Klaus [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, 52074 Aachen (Germany); Grützmacher, Detlev [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany)

    2014-10-15T23:59:59.000Z

    Generation of circularly polarized light in the extreme ultraviolet (EUV) spectral region (about 25 eV–250 eV) is highly desirable for applications in spectroscopy and microscopy but very challenging to achieve in a small-scale laboratory. We present a compact apparatus for generation of linearly and circularly polarized EUV radiation from a gas-discharge plasma light source between 50 eV and 70 eV photon energy. In this spectral range, the 3p absorption edges of Fe (54 eV), Co (60 eV), and Ni (67 eV) offer a high magnetic contrast often employed for magneto-optical and electron spectroscopy as well as for magnetic imaging. We simulated and designed an instrument for generation of linearly and circularly polarized EUV radiation and performed polarimetric measurements of the degree of linear and circular polarization. Furthermore, we demonstrate first measurements of the X-ray magnetic circular dichroism at the Co 3p absorption edge with a plasma-based EUV light source. Our approach opens the door for laboratory-based, element-selective spectroscopy of magnetic materials and spectro-microscopy of ferromagnetic domains.

  5. Advanced Turbulence Measurements and Signal Processing for Hydropower Flow Characterization

    E-Print Network [OSTI]

    Advanced Turbulence Measurements and Signal Processing for Hydropower Flow Characterization and flow characterization within full scale conventional hydropower systems, at marine and hydrokinetic

  6. Hot Particle and Turbulent Transport Effects on Resistive Instabilities

    SciTech Connect (OSTI)

    Brennan, Dylan P.

    2012-10-16T23:59:59.000Z

    This research project included two main thrusts; energetic particle effects on resistive MHD modes in tokamaks, and turbulence interactions with tearing modes in simplified geometry.

  7. Modulation of homogeneous turbulence seeded with finite size ...

    E-Print Network [OSTI]

    "K. Yeo; S. Dong; E. Climent; M.R. Maxey"

    2010-01-30T23:59:59.000Z

    Nov 10, 2009 ... of the energy spectrum of the turbulent velocity fluctuations with a uniform ..... collect within the cores of vortex tubes that may form in the flow.

  8. Scientists use plasma shaping to control turbulence in stellarators...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to control turbulence in stellarators By John Greenwald By John Greenwald October 21, 2014 Tweet Widget Google Plus One Share on Facebook Magnetic field strength in a...

  9. aperiodic magnetic turbulence: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    star formation and the interstellar medium. The density, pressure, and temperature distribution in a turbulent interstellar medium is described in comparison to a medium dominated...

  10. alfven wave turbulence: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    from 1 Solar Radius to 1 AU: an Analytical Treatment CERN Preprints Summary: We study the propagation, reflection, and turbulent dissipation of Alfven waves in coronal holes and...

  11. E-Print Network 3.0 - anisotropic magnetohydrodynamic turbulence...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Physics 57 Michigan Institute for Plasma Sci- Summary: of turbulent fluc- tuations in the solar wind. While magnetohydrodynamics remains the appro- priate theory... Michigan...

  12. Circular Higgs Factories & Possible Long-Term Strategy

    E-Print Network [OSTI]

    Zimmermann, F

    2013-01-01T23:59:59.000Z

    In 2012 two LHC experiments have discovered a new particle with a mass around 125 GeV, which appears to be the scalar Higgs boson of the Standard Model. To further examine this remarkable particle it could be produced in large numbers for precision studies by an e+e? collider operating near the ZH threshold at beam energies of 120 GeV, or, in the s-channel by a gamma-gamma collider with primary electron beam energies of 80 GeV, or by a high-energy electron-proton collider. In this talk I will discuss tentative design parameters, novel concepts and accelerator-physics challenges (1) for a high-luminosity lepton-hadron collider, bringing into collision a 60-GeV electron beam from an energy-recovery electron linac with one of the LHC hadron beams – LHeC –, (2) for a gamma-gamma Higgs-factory collider based on the reconfigured recirculating SC electron linac – SAPPHiRE – and (3) for a circular e+e? Higgs-factory collider in a new tunnel with a circumference of 80-100 km – TLEP. I will also discuss f...

  13. Preliminary Study Using ForwardPreliminary Study Using Forward Reaction Control System JetsReaction Control System Jets

    E-Print Network [OSTI]

    Valasek, John

    Preliminary Study Using ForwardPreliminary Study Using Forward Reaction Control System JetsReaction Control System Jets During Space Shuttle EntryDuring Space Shuttle Entry Carolina Restrepo Currently the shuttle uses only aft RCS jets for yaw control during entry Enough to handle present flight

  14. HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS

    SciTech Connect (OSTI)

    Yirak, Kristopher; Frank, Adam; Cunningham, Andrew J. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14620 (United States); Mitran, Sorin [Department of Mathematics, Applied Mathematics Program, University of North Carolina, Chapel Hill, NC 27599 (United States)], E-mail: yirak@pas.rochester.edu

    2009-04-20T23:59:59.000Z

    Herbig-Haro jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or 'pulsed' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper, we offer an alternative to 'pulsed' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of subradial clumps propagating through a moving interclump medium. Our models explore an idealization of this scenario by injecting small (r < r {sub jet}), dense ({rho}>{rho}{sub jet}) spheres embedded in an otherwise smooth interclump jet flow. The spheres are initialized with velocities differing from the jet velocity by {approx}15%. We find that the consequences of shifting from homogeneous to heterogeneous flows are significant as clumps interact with each other and with the interclump medium in a variety of ways. Structures which mimic what is expected from pulsed-jet models can form, as can be previously unseen, 'subradial' behaviors including backward facing bow shocks and off-axis working surfaces. While these small-scale structures have not been seen before in simulation studies, they are found in high-resolution jet observations. We discuss implications of our simulations for the interpretation of protostellar jets with regard to characterization of knots by a 'lifetime' or 'velocity history' approach as well as linking observed structures with central engines which produce the jets.

  15. Jet Vetoes Interfering with H->WW

    E-Print Network [OSTI]

    Ian Moult; Iain W. Stewart

    2014-09-08T23:59:59.000Z

    Far off-shell Higgs production in $H \\rightarrow WW,ZZ$, is a particularly powerful probe of Higgs properties, allowing one to disentangle Higgs width and coupling information unavailable in on-shell rate measurements. These measurements require an understanding of the cross section in the far off-shell region in the presence of realistic experimental cuts. We analytically study the effect of a $p_T$ jet veto on far off-shell cross sections, including signal-background interference, by utilizing hard functions in the soft collinear effective theory that are differential in the decay products of the $W/Z$. Summing large logarithms of $\\sqrt{\\hat s}/p_T^{veto}$, we find that the jet veto induces a strong dependence on the partonic centre of mass energy, $\\sqrt{\\hat s}$, and modifies distributions in $\\sqrt{\\hat s}$ or $M_T$. The example of $gg\\rightarrow H \\rightarrow WW$ is used to demonstrate these effects at next to leading log order. We also discuss the importance of jet vetoes and jet binning for the recent program to extract Higgs couplings and widths from far off-shell cross sections.

  16. The Rapidity Dependence of Jet Quenching

    E-Print Network [OSTI]

    Thorsten Renk

    2014-06-26T23:59:59.000Z

    The suppression of high transverse momentum (P_T) jets and hadrons in ultrarelativistic heavy-ion collisions with respect to a p-p baseline in terms of the nuclear suppression factor R_AA is one of the key observables to gauge the density of a hot and dense QCD medium. However, the suppression measured by R_AA is not a straightforward measure of the medium properties, the value of the observable also depends on the ratio of quark to gluon jets and on the slope of the hard parton spectrum, which explains why R_AA is found to be fairly similar at RHIC and LHC despite the very different dynamics. Measuring high P_T jets and hadrons at forward rapidity offers the same possibility of varying medium density, parton mixture and spectral slope without the need to compare across different sqrt(s) and experiments. In this work, the well-tested jet quenching Monte-Carlo (MC) framework YaJEM is utilized to compute the rapidity dependence of R_AA for three test cases.

  17. The interaction between two radial jets

    E-Print Network [OSTI]

    Gruber, Thomas Clifton

    2012-06-07T23:59:59.000Z

    on an impingement surface with high surface heat and mass transfer. The objective of this study was to characterize the flow, surface pressure, and heat transfer for two radial jets as a function of nozzle geometry, in order to be able to design arrays of radial...

  18. Models comparison for JET polarimeter data

    SciTech Connect (OSTI)

    Mazzotta, C.; Orsitto, F. P.; Giovannozzi, E. [Centro Ricerche Energia Frascati, Euratom-ENEA Association, Frascati (Italy); Boboc, A.; Tudisco, O.; Zabeo, L. [Association EURATOM-UKAEA Culham Science Centre Abingdon 0X14 3DB (UK) (United Kingdom); Brombin, M.; Murari, A. [Consorzio RFX, Euratom-ENEA Association, Padova (Italy)

    2008-03-12T23:59:59.000Z

    A complete comparison between the theory and the measurements in polarimetry was done by using the Far Infrared Polarimeter at JET. More than 300 shots were analyzed, including a wide spectrum of JET scenarios in all critical conditions for polarimetry: high density, high and very low fields, high temperatures.This work is aimed at the demonstration of the robustness of the theoretical models for the JET polarimeter measurements in the perspective of using these models for ITER like plasma scenarios . In this context, an assessment was performed on how the line-integrated plasma density along the central vertical chord of FIR polarimeter could be evaluated using the Cotton-Mouton effect and its possible concrete use to correct fringe jumps of the interferometer.The models considered are: i) the rigorous numerical solution of the Stokes propagation equations, using dielectric tensor evaluated from JET equilibrium and Thomson scattering [1,2]; ii) two types of approximated solutions [2,3] and iii) the Guenther empirical model [4] that considers the mutual effect between Cotton-Mouton and Faraday rotation angle. The model calculations have been compared with polarimeter measurements for the Cotton-Mouton phase shift.The agreement with theory is satisfactory within the limits of experimental errors [3].

  19. HOT ELECTROMAGNETIC OUTFLOWS. II. JET BREAKOUT

    SciTech Connect (OSTI)

    Russo, Matthew [Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 (Canada); Thompson, Christopher [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

    2013-08-20T23:59:59.000Z

    We consider the interaction between radiation, matter, and a magnetic field in a compact, relativistic jet. The entrained matter accelerates outward as the jet breaks out of a star or other confining medium. In some circumstances, such as gamma-ray bursts (GRBs), the magnetization of the jet is greatly reduced by an advected radiation field while the jet is optically thick to scattering. Where magnetic flux surfaces diverge rapidly, a strong outward Lorentz force develops and radiation and matter begin to decouple. The increase in magnetization is coupled to a rapid growth in Lorentz factor. We take two approaches to this problem. The first examines the flow outside the fast magnetosonic critical surface, and calculates the flow speed and the angular distribution of the radiation field over a range of scattering depths. The second considers the flow structure on both sides of the critical surface in the optically thin regime, using a relaxation method. In both approaches, we find how the terminal Lorentz factor and radial profile of the outflow depend on the radiation intensity and optical depth at breakout. The effect of bulk Compton scattering on the radiation spectrum is calculated by a Monte Carlo method, while neglecting the effects of internal dissipation. The peak of the scattered spectrum sits near the seed peak if radiation pressure dominates the acceleration, but is pushed to a higher frequency if the Lorentz force dominates. The unscattered seed radiation can form a distinct, low-frequency component of the spectrum, especially if the magnetic Poynting flux dominates.

  20. Dynamics, Structure, and Emission of Electron-Positron Jets

    E-Print Network [OSTI]

    A. Levinson

    1997-08-10T23:59:59.000Z

    The theory of gamma-ray emission from e$^{\\pm}$ jets and the implications for jet formation, dynamics and structure are reviewed. In particular, possible carriers of the jet's thrust on small scales, the transition from electromagnetic to particle dominance in Poynting flux jets, formation of pair cascades, synchrotron emission by cascading pairs, and formation of shocks due to unsteadiness in the jet parameters are considered, with emphasis on the observational consequences. Some recent progress in modeling transient emission from blazars is also briefly discussed.

  1. Gyrokinetic particle simulation for thermonuclear plasma turbulence studies in magnetic confinement.

    E-Print Network [OSTI]

    Janhunen, Salomon

    2013-01-01T23:59:59.000Z

    ??Thermal transport in a magnetised plasma is believed to be substantially enhanced due to turbulence. The ELMFIRE code has been developed for tokamak plasma turbulence studies… (more)

  2. E-Print Network 3.0 - astrophysical turbulent plasma Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Turbulence in Molecular Clouds SciDAC 2009 - Astrophysics - San... Kolmogorov's phenomenology to supersonic regime? Turbulence in ... Source: Kritsuk, Alexei - Center for...

  3. E-Print Network 3.0 - atmospheric turbulence structures Sample...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Elperin, Tov - Department of Mechanical Engineering, Ben-Gurion University Collection: Engineering 12 Turbulence and turbulent mixing in natural fluids This article has been...

  4. E-Print Network 3.0 - atmospheric turbulence Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Summary: by dissipation of the turbulent energy and tur- bulent eddies will transport heat to different atmospheric re... ., MST radar studies of wind and turbulence in the...

  5. ?Linear Gas Jet with Tailored Density Profile"

    SciTech Connect (OSTI)

    KRISHNAN, Mahadevan

    2012-12-10T23:59:59.000Z

    Supersonic, highly collimated gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for Laser Plasma Accelerators (LPA) . Present gas jets have lengths of only 2-4 mm at densities of 1-4E19 cm-3, sufficient for self trapping and electron acceleration to energies up to ~150 MeV. Capillary structures 3 cm long have been used to accelerate beams up to 1 GeV. Capillary discharges used in LPAs serve to guide the pump laser and optimize the energy gain. A wall-stabilized capillary discharge provides a transverse profile across the channel that helps guide the laser and combat diffraction. Gas injection via a fast nozzle at one end provides some longitudinal density control, to improve the coupling. Gas jets with uniform or controlled density profiles may be used to control electron bunch injection and are being integrated into capillary experiments to add tuning of density. The gas jet for electron injection has not yet been optimized. Our Ph-I results have provided the LPA community with an alternative path to realizing a 2-3GeV electron bunch using just a gas jet. For example, our slit/blade combination gives a 15-20mm long acceleration path with tunable density profile, serving as an alternative to a 20-mm long capillary discharge with gas injection at one end. In Ph-II, we will extend these results to longer nozzles, to see whether we can synthesize 30 or 40-mm long plasma channels for LPAs.

  6. Adaptive LES Methodology for Turbulent Flow Simulations

    SciTech Connect (OSTI)

    Oleg V. Vasilyev

    2008-06-12T23:59:59.000Z

    Although turbulent flows are common in the world around us, a solution to the fundamental equations that govern turbulence still eludes the scientific community. Turbulence has often been called one of the last unsolved problem in classical physics, yet it is clear that the need to accurately predict the effect of turbulent flows impacts virtually every field of science and engineering. As an example, a critical step in making modern computational tools useful in designing aircraft is to be able to accurately predict the lift, drag, and other aerodynamic characteristics in numerical simulations in a reasonable amount of time. Simulations that take months to years to complete are much less useful to the design cycle. Much work has been done toward this goal (Lee-Rausch et al. 2003, Jameson 2003) and as cost effective accurate tools for simulating turbulent flows evolve, we will all benefit from new scientific and engineering breakthroughs. The problem of simulating high Reynolds number (Re) turbulent flows of engineering and scientific interest would have been solved with the advent of Direct Numerical Simulation (DNS) techniques if unlimited computing power, memory, and time could be applied to each particular problem. Yet, given the current and near future computational resources that exist and a reasonable limit on the amount of time an engineer or scientist can wait for a result, the DNS technique will not be useful for more than 'unit' problems for the foreseeable future (Moin & Kim 1997, Jimenez & Moin 1991). The high computational cost for the DNS of three dimensional turbulent flows results from the fact that they have eddies of significant energy in a range of scales from the characteristic length scale of the flow all the way down to the Kolmogorov length scale. The actual cost of doing a three dimensional DNS scales as Re{sup 9/4} due to the large disparity in scales that need to be fully resolved. State-of-the-art DNS calculations of isotropic turbulence have recently been completed at the Japanese Earth Simulator (Yokokawa et al. 2002, Kaneda et al. 2003) using a resolution of 40963 (approximately 10{sup 11}) grid points with a Taylor-scale Reynolds number of 1217 (Re {approx} 10{sup 6}). Impressive as these calculations are, performed on one of the world's fastest super computers, more brute computational power would be needed to simulate the flow over the fuselage of a commercial aircraft at cruising speed. Such a calculation would require on the order of 10{sup 16} grid points and would have a Reynolds number in the range of 108. Such a calculation would take several thousand years to simulate one minute of flight time on today's fastest super computers (Moin & Kim 1997). Even using state-of-the-art zonal approaches, which allow DNS calculations that resolve the necessary range of scales within predefined 'zones' in the flow domain, this calculation would take far too long for the result to be of engineering interest when it is finally obtained. Since computing power, memory, and time are all scarce resources, the problem of simulating turbulent flows has become one of how to abstract or simplify the complexity of the physics represented in the full Navier-Stokes (NS) equations in such a way that the 'important' physics of the problem is captured at a lower cost. To do this, a portion of the modes of the turbulent flow field needs to be approximated by a low order model that is cheaper than the full NS calculation. This model can then be used along with a numerical simulation of the 'important' modes of the problem that cannot be well represented by the model. The decision of what part of the physics to model and what kind of model to use has to be based on what physical properties are considered 'important' for the problem. It should be noted that 'nothing is free', so any use of a low order model will by definition lose some information about the original flow.

  7. The Temperature of Interstellar Clouds from Turbulent Heating

    E-Print Network [OSTI]

    Liubin Pan; Paolo Padoan

    2008-06-30T23:59:59.000Z

    To evaluate the effect of turbulent heating in the thermal balance of interstellar clouds, we develop an extension of the log-Poisson intermittency model to supersonic turbulence. The model depends on a parameter, d, interpreted as the dimension of the most dissipative structures. By comparing the model with the probability distribution of the turbulent dissipation rate in a simulation of supersonic and super-Alfvenic turbulence, we find a best-fit value of d=1.64. We apply this intermittency model to the computation of the mass-weighted probability distribution of the gas temperature of molecular clouds, high-mass star-forming cores, and cold diffuse HI clouds. Our main results are: i) The mean gas temperature in molecular clouds can be explained as the effect of turbulent heating alone, while cosmic ray heating may dominate only in regions where the turbulent heating is low; ii) The mean gas temperature in high-mass star-forming cores with typical FWHM of ~6 km/s (corresponding to a 1D rms velocity of 2.5 km/s) may be completely controlled by turbulent heating, which predicts a mean value of approximately 36 K, two to three times larger than the mean gas temperature in the absence of turbulent heating; iii) The intermittency of the turbulent heating can generate enough hot regions in cold diffuse HI clouds to explain the observed CH+ abundance, if the rms velocity on a scale of 1 pc is at least 3 km/s, in agreement with previous results based on incompressible turbulence. Because of its importance in the thermal balance of molecular clouds and high-mass star-forming cores, the process of turbulent heating may be central in setting the characteristic stellar mass and in regulating molecular chemical reactions.

  8. Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: I. Turbulence Statistics

    SciTech Connect (OSTI)

    Klein, R I; Li, P S; McKee, C F; Fisher, R

    2008-04-10T23:59:59.000Z

    Most numerical investigations on the role of magnetic fields in turbulent molecular clouds (MCs) are based on ideal magneto-hydrodynamics (MHD). However, MCs are weakly ionized, so that the time scale required for the magnetic field to diffuse through the neutral component of the plasma by ambipolar diffusion (AD) can be comparable to the dynamical time scale. We have performed a series of 256{sup 3} and 512{sup 3} simulations on supersonic but sub-Alfvenic turbulent systems with AD using the Heavy-Ion Approximation developed in Li et al. (2006). Our calculations are based on the assumption that the number of ions is conserved, but we show that these results approximately apply to the case of time-dependent ionization in molecular clouds as well. Convergence studies allow us to determine the optimal value of the ionization mass fraction when using the heavy-ion approximation for low Mach number, sub-Alfvenic turbulent systems. We find that ambipolar diffusion steepens the velocity and magnetic power spectra compared to the ideal MHD case. Changes in the density PDF, total magnetic energy, and ionization fraction are determined as a function of the AD Reynolds number. The power spectra for the neutral gas properties of a strongly magnetized medium with a low AD Reynolds number are similar to those for a weakly magnetized medium; in particular, the power spectrum of the neutral velocity is close to that for Burgers turbulence.

  9. Section 10: Turbulence and reactive flows 1 Section 10: Turbulence and reactive flows

    E-Print Network [OSTI]

    Kohlenbach, Ulrich

    premixed combustion is recently a theme of interest in gas turbines and other industrial applications flames #12;2 Section 10: Turbulence and reactive flows for gas turbine application. In: International Gas combustion LES in- cluding thickened flame model A. Hosseinzadeh, A. Sadiki, J. Janicka (TU Darmstadt) Lean

  10. Development of vortex state in circular magnetic nanodots: Theory and experiment RID A-9247-2009

    E-Print Network [OSTI]

    Mejia-Lopez, J.; Altbir, D.; Landeros, P.; Escrig, J.; Romero, A. H.; Roshchin, Igor V.; Li, C-P; Fitzsimmons, M. R.; Batlle, X.; Schuller, Ivan K.

    2010-01-01T23:59:59.000Z

    We compare magnetic reversal of nanostructured circular magnetic dots of different sizes. This comparison is based on superconducting quantum interference device (SQUID) magnetometry, neutron scattering, Monte Carlo simulation, and analytical...

  11. Experimental investigation of an oscillating circular piston positive displacement flowmeter: I - Piston movement and pressure losses.

    E-Print Network [OSTI]

    Morton, Charlotte E; Hutchings, Ian M; Baker, Roger C

    Tests of an oscillating circular piston positive displacement flowmeter are described which focused on the effect on pressure drop across the meter of variation in key parameters. These included flow rate, liquid density and viscosity, mass...

  12. Experimental investigation of an oscillating circular piston positive displacement flowmeter: II - Leakage flows and wear tests.

    E-Print Network [OSTI]

    Morton, Charlotte E; Baker, Roger C; Hutchings, Ian M

    Experimental data from an oscillating circular piston positive displacement flowmeter are described which focused on leakage flows and wear. This is the second part of a two part paper on the experimental tests, the first part concerned piston...

  13. E-Print Network 3.0 - adiabatic circular cylinder Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1983;105:161-7. 2 Balabani S, Yianneskis M... on the flow past a circular cylinder at a subcritical ... Source: Luo, Xiaoyu - Department of Mathematics, University of Glasgow...

  14. Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids

    E-Print Network [OSTI]

    Kristopher Yirak; Adam Frank; Andrew J. Cunningham; Sorin Mitran

    2008-05-30T23:59:59.000Z

    Herbig-Haro (HH) jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or ``pulsed'' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper we offer an alternative to ``pulsed'' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of sub-radial clumps propagating through a moving inter-clump medium. Our models explore an idealization of this scenario by injecting small ($r\\rho_{jet}$) spheres embedded in an otherwise smooth inter-clump jet flow. The spheres are initialized with velocities differing from the jet velocity by $\\sim15$%. We find the consequences of shifting from homogeneous to heterogeneous flows are significant as clumps interact with each other and with the inter-clump medium in a variety of ways. Structures which mimic what is expected from pulsed-jet models can form, as can previously unseen ``sub-radial'' behaviors including backward facing bow shocks and off-axis working surfaces. While these small-scale structures have not been seen before in simulation studies, they are found in high resolution jet observations. We discuss implications of our simulations for the interpretation of protostellar jets with regard to characterization of knots by a ``lifetime'' or ``velocity history'' approach as well as linking observed structures with central engines which produce the jets.

  15. Use of Crystals for High Energy Photon Beam Linear Polarization Conversion into Circular

    E-Print Network [OSTI]

    N. Z. Akopov; A. B. Apyan; S. M. Darbinyan

    2000-02-17T23:59:59.000Z

    The possibility to convert the photon beam linear polarization into circular one at photon energies of hundreds GeV with the use of crystals is considered. The energy and orientation dependencies of refractive indexes are investigated in case of diamond, silicon and germanium crystal targets. To maximize the values for figure of merit, the corresponding crystal optimal orientation angles and thickness are found. The degree of circular polarization and intensity of photon beam are estimated and possibility of experimental realization is discussed.

  16. Thermal shallow water models of geostrophic turbulence in Jovian atmospheres

    SciTech Connect (OSTI)

    Warneford, Emma S., E-mail: emma.warneford@maths.ox.ac.uk; Dellar, Paul J., E-mail: dellar@maths.ox.ac.uk [OCIAM, Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Oxford OX2 6GG (United Kingdom)

    2014-01-15T23:59:59.000Z

    Conventional shallow water theory successfully reproduces many key features of the Jovian atmosphere: a mixture of coherent vortices and stable, large-scale, zonal jets whose amplitude decreases with distance from the equator. However, both freely decaying and forced-dissipative simulations of the shallow water equations in Jovian parameter regimes invariably yield retrograde equatorial jets, while Jupiter itself has a strong prograde equatorial jet. Simulations by Scott and Polvani [“Equatorial superrotation in shallow atmospheres,” Geophys. Res. Lett. 35, L24202 (2008)] have produced prograde equatorial jets through the addition of a model for radiative relaxation in the shallow water height equation. However, their model does not conserve mass or momentum in the active layer, and produces mid-latitude jets much weaker than the equatorial jet. We present the thermal shallow water equations as an alternative model for Jovian atmospheres. These equations permit horizontal variations in the thermodynamic properties of the fluid within the active layer. We incorporate a radiative relaxation term in the separate temperature equation, leaving the mass and momentum conservation equations untouched. Simulations of this model in the Jovian regime yield a strong prograde equatorial jet, and larger amplitude mid-latitude jets than the Scott and Polvani model. For both models, the slope of the non-zonal energy spectra is consistent with the classic Kolmogorov scaling, and the slope of the zonal energy spectra is consistent with the much steeper spectrum observed for Jupiter. We also perform simulations of the thermal shallow water equations for Neptunian parameter values, with a radiative relaxation time scale calculated for the same 25 mbar pressure level we used for Jupiter. These Neptunian simulations reproduce the broad, retrograde equatorial jet and prograde mid-latitude jets seen in observations. The much longer radiative time scale for the colder planet Neptune explains the transition from a prograde to a retrograde equatorial jet, while the broader jets are due to the deformation radius being a larger fraction of the planetary radius.

  17. Turbulence-Chemistry Interaction in Lean Premixed Hydrogen Combustion

    E-Print Network [OSTI]

    Bell, John B.

    alternatives to traditional petroleum and natural gas fuels. Burning under lean condi- tions reduces of conditions expected from gas turbine combustors. At these higher turbulence in- tensities, hydrogen flamesTurbulence-Chemistry Interaction in Lean Premixed Hydrogen Combustion A. J. Aspden1,2 , M. S. Day2

  18. Fluctuations of energy flux in wave turbulence Eric Falcon,1

    E-Print Network [OSTI]

    Falcon, Eric

    Fluctuations of energy flux in wave turbulence ´Eric Falcon,1 S´ebastien Auma^itre,2 Claudio Falc gravity and capillary wave turbulence in a statistically stationary regime displays fluctuations much interactions transfer kinetic energy toward small scales where viscous dissipation takes place

  19. Characterizing Ocean Turbulence from Argo, Acoustic Doppler, and Simulation Data

    E-Print Network [OSTI]

    Fox-Kemper, Baylor

    . TurbSim models statistics at the height of a turbine hub (5m) well, but do not model coherent eventsCharacterizing Ocean Turbulence from Argo, Acoustic Doppler, and Simulation Data Katherine Mc Ocean Turbulence from Argo, Acoustic Doppler, and Simulation Data written by Katherine McCaffrey has

  20. Turbulence intensity pulse propagation with self-consistent nonlinear noise

    SciTech Connect (OSTI)

    Wang, Z. H. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Department of Physics and Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, California 92093-0424 (United States); Diamond, P. H. [Department of Physics and Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, California 92093-0424 (United States); WCI Center for Fusion Theory, National Fusion Research Institute, Gwahangno 113, Yuseong-gu, Daejeon 305-333 (Korea, Republic of); Guercan, Oe. D. [Laboratoire de Physique des Plasmas, Ecole Polytechnique-CNRS, 91128 Palaiseau Cedex (France); Garbet, X. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); Wang, X. G. [School of Physics, Peking University, Beijing 100871 (China)

    2011-03-15T23:59:59.000Z

    A model of turbulence intensity spreading with self-consistent nonlinear noise is derived systematically for the simple dynamical model of resistivity gradient driven turbulence. Local effective drive, thermal conduction damping, nonlinear coupling, and spatial scattering effects are included. As a consequence of nonlinear mode coupling processes (i.e., triad mode interactions), turbulence energy can be spatially scattered, leading to turbulence propagation and spreading. However, the range of any nonlinear mode interactions of the background with a test mode is restricted to within a few mode scale widths from the test mode rational surface. The speed of a turbulent spreading front is calculated. This front speed is effectively constant on macroscopic scales. We show that the effect of self-consistent nonlinear noise on the intensity front speed is modest, as a consequence of the ordering {Delta}{sub c}turbulence correlation length and L{sub f} is the scale length of the front's leading edge. The implications of these results for turbulence spreading models and the important differences between self-consistent mode coupling noise and ad hoc external noise are discussed. The broader implications of these results for turbulence front propagation are identified and explained.

  1. Lagrangian tetrad dynamics and the phenomenology of turbulence Michael Chertkov

    E-Print Network [OSTI]

    Chertkov, Mikhael

    Lagrangian tetrad dynamics and the phenomenology of turbulence Michael Chertkov Department Jersey 07974 Received 23 September 1998; accepted 21 April 1999 A new phenomenological model of turbulent in the right direction one must rely on phenomenology. One reason for pursuing the modeling approach

  2. The Turbulent Alfvenic Aurora C. C. Chaston,1

    E-Print Network [OSTI]

    California at Berkeley, University of

    The Turbulent Alfve´nic Aurora C. C. Chaston,1 C. Salem,1 J. W. Bonnell,1 C. W. Carlson,1 R. E) It is demonstrated from observations that the Alfve´nic aurora may be powered by a turbulent cascade transverse acceleration of electrons from near-Earth space to form the aurora. We find that regions of Alfve´n wave

  3. Fractal dimension and turbulence in Giant HII Regions

    E-Print Network [OSTI]

    Caicedo-Ortiz, H E; López-Bonilla, J; Castañeda, H O

    2015-01-01T23:59:59.000Z

    We have measured the fractal dimensions of the Giant HII Regions Hubble X and Hubble V in NGC6822 using images obtained with the Hubble's Wide Field Planetary Camera 2 (WFPC2). These measures are associated with the turbulence observed in these regions, which is quantified through the velocity dispersion of emission lines in the visible. Our results suggest low turbulence behaviour.

  4. ANISOTROPY LENGTHENS THE DECAY TIME OF TURBULENCE IN MOLECULAR CLOUDS

    SciTech Connect (OSTI)

    Hansen, Charles E.; McKee, Christopher F.; Klein, Richard I. [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2011-09-01T23:59:59.000Z

    The decay of isothermal turbulence with velocity anisotropy is investigated using computational simulations and synthetic observations. We decompose the turbulence into isotropic and anisotropic components with total velocity dispersions {sigma}{sub iso} and {sigma}{sub ani}, respectively. We find that the decay rate of the turbulence depends on the crossing time of the isotropic component only. A cloud of size L with significant anisotropy in its turbulence has a dissipation time, t{sub diss} = L/(2{sigma}{sub iso}). This translates into turbulent energy decay rates on the cloud scale that can be much lower for anisotropic turbulence than for isotropic turbulence. To help future observations determine whether observed molecular clouds have the level of anisotropy required to maintain the observed level of turbulence over their lifetimes, we performed a principal component analysis on our simulated clouds. Even with projection effects washing out the anisotropic signal, there is a measurable difference in the axis-constrained principal component analysis performed in directions parallel and perpendicular to the direction of maximum velocity dispersion. When this relative difference, {psi}, is 0.1, there is enough anisotropy for the dissipation time to triple the expected isotropic value. We provide a fit for converting {psi} into an estimate for the dissipation time, t{sub diss}.

  5. Supersonic turbulent boundary layers with periodic mechanical non-equilibrium

    E-Print Network [OSTI]

    Ekoto, Isaac Wesley

    2007-04-25T23:59:59.000Z

    . It was documented that proper roughness selection coupled with a sufficiently strong favorable pressure gradient produced regions of �negative� production in the transport of turbulent stress. This led to localized areas of significant turbulence stress...

  6. Heat release response of acoustically forced turbulent premixed flamesrole

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    Heat release response of acoustically forced turbulent premixed flames­role of kinematic surface to coherent forcing and turbulent fluctuations are coupled even at linear order in coherent forcing amplitude, ea, due to flame propagation (kinematic restoration). This coupling effectively causes

  7. In-Flight Measurements of Freestream Atmospheric Turbulence Intensities

    E-Print Network [OSTI]

    Fanning, Joshua 1987-

    2012-11-05T23:59:59.000Z

    difference in turbulence intensity. It has been determined through this work that the levels of freestream turbulence range from 0.023% - 0.047% with an average of 0.035%. These levels were reached through the use of temporal correlations to remove electronic...

  8. Modeling of combustion noise spectrum from turbulent premixed flames

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Modeling of combustion noise spectrum from turbulent premixed flames Y. Liu, A. P. Dowling, T. D, Nantes, France 2321 #12;Turbulent combustion processes generate sound radiation due to temporal changes, this temporal correlation and its role in the modeling of combustion noise spectrum are studied by analyzing

  9. AIAA980057 RELATING TURBULENCE TO WIND TURBINE BLADE LOADS

    E-Print Network [OSTI]

    Sweetman, Bert

    AIAA­98­0057 RELATING TURBULENCE TO WIND TURBINE BLADE LOADS: PARAMETRIC STUDY WITH MULTIPLE that is most useful in estimating fatigue loads on wind turbine blades. The histograms of rainflow counted turbulence measures---can be used to estimate fatigue loads on wind turbine blades. We first de­ scribe

  10. RESEARCH ARTICLE Development and characterization of a variable turbulence

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    (7):1037­1048, 2009), where variable blockage ratio slots are located upstream of a contoured nozzle. Vortical A Nozzle exit area E Power spectral density ReD Geometric Reynolds number Rel Turbulent Reynolds number SLRESEARCH ARTICLE Development and characterization of a variable turbulence generation system A

  11. Center for Turbulence Research Annual Research Briefs 2001

    E-Print Network [OSTI]

    Apte, Sourabh V.

    Center for Turbulence Research Annual Research Briefs 2001 3 Large-eddy simulation of gas turbine, and solver capable of performing large-eddy simulation in geometries as complex as the combustor of a gas-turbine' grids encountered in complex geometries such as the Pratt & Whitney combustor. · Turbulent validations

  12. Taming turbulence in magnetized plasmas: from fusion energy to

    E-Print Network [OSTI]

    occurs (fusion of particle beams will not work...) Thermonuclear fusion in a confined plasma (T~10 keTaming turbulence in magnetized plasmas: from fusion energy to black hole accretion disks Troy?: In fusion plasmas turbulent leakage of heat and particles is a key issue. Sheared flow can suppress

  13. Relationship between ignition processes and the lift-off length of diesel fuel jets.

    SciTech Connect (OSTI)

    Siebers, Dennis L.; Idicheria, Cherian A.; Pickett, Lyle M.

    2005-06-01T23:59:59.000Z

    The reaction zone of a diesel fuel jet stabilizes at a location downstream of the fuel injector once the initial autoignition phase is over. This distance is referred to as flame lift-off length. Recent investigations have examined the effects of a wide range of parameters (injection pressure, orifice diameter, and ambient gas temperature, density and oxygen concentration) on lift-off length under quiescent diesel conditions. Many of the experimental trends in lift-off length were in agreement with scaling laws developed for turbulent, premixed flame propagation in gas-jet lifted flames at atmospheric conditions. However, several effects did not correlate with the gas-jet scaling laws, suggesting that other mechanisms could be important to lift-off stabilization at diesel conditions. This paper shows experimental evidence that ignition processes affect diesel lift-off stabilization. Experiments were performed in the same optically-accessible combustion vessel as the previous lift-off research. The experimental results show that the ignition quality of a fuel affects lift-off. Fuels with shorter ignition delays generally produce shorter lift-off lengths. In addition, a cool flame is found upstream of, or near the same axial location as, the quasi-steady lift-off length, indicating that first-stage ignition processes affect lift-off. High-speed chemiluminescence imaging also shows that high-temperature self-ignition occasionally occurs in kernels that are upstream of, and detached from, the high-temperature reaction zone downstream, suggesting that the lift-off stabilization is not by flame propagation into upstream reactants in this instance. Finally, analysis of the previous lift-off length database shows that the time-scale for jet mixing from injector-tip orifice to lift-off length collapses to an Arrhenius-type expression, a common method for describing ignition delay in diesel sprays. This Arrhenius-based lift-off length correlation shows comparable accuracy as a previous power-law fit of the No.2 diesel lift-off length database.

  14. Stretching of polymers in a turbulent environment

    E-Print Network [OSTI]

    Bruno Eckhardt; Jochen Kronjaeger; Joerg Schumacher

    2002-01-20T23:59:59.000Z

    The interaction of polymers with small-scale velocity gradients can trigger a coil-stretch transition in the polymers. We analyze this transition within a direct numerical simulation of shear turbulence with an Oldroyd-B model for the polymer. In the coiled state the lengths of polymers are distributed algebraically with an exponent alpha=2 gamma-1/De, where gamma is a characteristic stretching rate of the flow and De the Deborah number. In the stretched state we demonstrate that the length distribution of the polymers is limited by the feedback to the flow.

  15. Supercomputers Capture Turbulence in the Solar Wind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassiveSubmittedStatus TomAbout »Lab (NewportSuccess Stories T ECapture Turbulence in

  16. anisotropic langmuir turbulence: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for emission produced in various kinds of astrophysical jets, in particular, prompt gamma-ray burst spectra, including X-ray excesses and prompt optical flashes. Gregory D....

  17. Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model

    E-Print Network [OSTI]

    Chien, Li-Chun

    2010-01-01T23:59:59.000Z

    Giampaolo, T. (2009). The gas turbine handbook : principlesnatural gas. J. Eng. Gas Turbines Power, Masri, A. , Dibble,premixed jet flames at gas turbine conditions. The transient

  18. Fusion Rules and Conditional Statistics in Turbulent Advection

    E-Print Network [OSTI]

    Emily S. C. Ching; Victor S. L'vov; Itamar Procaccia

    1996-07-02T23:59:59.000Z

    Fusion rules in turbulence address the asymptotic properties of many-point correlation functions when some of the coordinates are very close to each other. Here we put to experimental test some non-trivial consequences of the fusion rules for scalar correlations in turbulence. To this aim we examine passive turbulent advection as well as convective turbulence. Adding one assumption to the fusion rules one obtains a prediction for universal conditional statistics of gradient fields. We examine the conditional average of the scalar dissipation field $\\left$ for $R$ in the inertial range, and find that it is linear in $T(\\B.r+\\B.R)-T(\\B.r)$ with a fully determined proportionality constant. The implications of these findings for the general scaling theory of scalar turbulence are discussed.

  19. The energetic coupling of scales in gyrokinetic plasma turbulence

    SciTech Connect (OSTI)

    Teaca, Bogdan, E-mail: bogdan.teaca@coventry.ac.uk [Applied Mathematics Research Centre, Coventry University, Coventry CV1 5FB (United Kingdom); Max-Planck für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Max-Planck/Princeton Center for Plasma Physics (Germany); Navarro, Alejandro Bañón, E-mail: alejandro.banon.navarro@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Jenko, Frank, E-mail: frank.jenko@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Max-Planck/Princeton Center for Plasma Physics (Germany)

    2014-07-15T23:59:59.000Z

    In magnetized plasma turbulence, the couplings of perpendicular spatial scales that arise due to the nonlinear interactions are analyzed from the perspective of the free-energy exchanges. The plasmas considered here, with appropriate ion or electron adiabatic electro-neutrality responses, are described by the gyrokinetic formalism in a toroidal magnetic geometry. Turbulence develops due to the electrostatic fluctuations driven by temperature gradient instabilities, either ion temperature gradient (ITG) or electron temperature gradient (ETG). The analysis consists in decomposing the system into a series of scale structures, while accounting separately for contributions made by modes possessing special symmetries (e.g., the zonal flow modes). The interaction of these scales is analyzed using the energy transfer functions, including a forward and backward decomposition, scale fluxes, and locality functions. The comparison between the ITG and ETG cases shows that ETG turbulence has a more pronounced classical turbulent behavior, exhibiting a stronger energy cascade, with implications for gyrokinetic turbulence modeling.

  20. MHD Turbulence: Properties of Alfven, Slow and Fast Modes

    E-Print Network [OSTI]

    A. Lazarian; A. Beresnyak

    2005-05-29T23:59:59.000Z

    We summarise basic properties of MHD turbulence. First, MHD turbulence is not so messy as it is believed. In fact, the notion of strong non-linear coupling of compressible and incompressible motions along MHD cascade is not tenable. Alfven, slow and fast modes of MHD turbulence follow their own cascades and exhibit degrees of anisotropy consistent with theoretical expectations. Second, the fast decay of turbulence is not related to the compressibility of fluid. Rates of decay of compressible and incompressible motions are very similar. Third, the properties of Alfven and slow modes are similar to their counterparts in the incompressible MHD. The properties of fast modes are similar to accoustic turbulence, which does require more studies. Fourth, the density at low Mach numbers and logarithm of density at higher Mach numbers exhibit Kolmogorov-type spectrum.

  1. Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence

    SciTech Connect (OSTI)

    Donato, S.; Servidio, S.; Carbone, V. [Dipartimento di Fisica, Universita della Calabria, I-87036 Cosenza (Italy); Dmitruk, P. [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Fisica de Buenos Aires, CONICET, Buenos Aires (Argentina); Shay, M. A.; Matthaeus, W. H. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Cassak, P. A. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)

    2012-09-15T23:59:59.000Z

    The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed by comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis reveals that the Hall term plays an important role in turbulence, in which magnetic islands simultaneously reconnect in a complex way. In particular, an increase of the Hall parameter, the ratio of ion skin depth to system size, broadens the distribution of reconnection rates relative to the MHD case. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures in analogy to laminar studies, leading locally to faster reconnection processes in this case of reconnection embedded in turbulence. This study supports the idea that the global rate of energy dissipation is controlled by the large scale turbulence, but suggests that the distribution of the reconnection rates within the turbulent system is sensitive to the microphysics at the reconnection sites.

  2. Generalized universal instability: Transient linear amplification and subcritical turbulence

    E-Print Network [OSTI]

    Landreman, Matt; Dorland, William

    2015-01-01T23:59:59.000Z

    In this work we numerically demonstrate both significant transient (i.e. non-modal) linear amplification and sustained nonlinear turbulence in a kinetic plasma system with no unstable eigenmodes. The particular system considered is an electrostatic plasma slab with magnetic shear, kinetic electrons and ions, weak collisions, and a density gradient, but with no temperature gradient. In contrast to hydrodynamic examples of non-modal growth and subcritical turbulence, here there is no sheared flow in the equilibrium. Significant transient linear amplification is found when the magnetic shear and collisionality are weak. It is also demonstrated that nonlinear turbulence can be sustained if initialized at sufficient amplitude. We prove these two phenomena are related: when sustained turbulence occurs without unstable eigenmodes, states that are typical of the turbulence must yield transient linear amplification of the gyrokinetic free energy.

  3. Internal wave energy radiated from a turbulent mixed layer

    SciTech Connect (OSTI)

    Munroe, James R., E-mail: jmunroe@mun.ca [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7 (Canada); Sutherland, Bruce R., E-mail: bsuther@ualberta.ca [Departments of Physics and Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

    2014-09-15T23:59:59.000Z

    We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy density. The internal waves are measured using synthetic schlieren to determine their amplitudes, frequencies, and energy density. We also perform fully nonlinear numerical simulations restricted to two dimensions but in a horizontally periodic domain. These clearly demonstrate that internal waves are generated by transient eddies at the integral length scale of turbulence and which translate with the background shear along the base of the mixed layer. In both experiments and simulations we find that the energy density of the generated waves is 1%–3% of the turbulent kinetic energy density of the turbulent layer.

  4. Statistical models for spatial patterns of inertial particles in turbulence

    E-Print Network [OSTI]

    Gustavsson, K

    2014-01-01T23:59:59.000Z

    The dynamics of particles suspended in turbulent flows is of fundamental importance for a wide range of questions in astrophysics, cloud physics, oceanography, and in technology. Laboratory experiments and direct numerical simulations have demonstrated that heavy particles respond in intricate ways to turbulent fluctuations of the carrying fluid: independent particles may cluster together and form spatial patterns even though the fluid is incompressible, and the relative speeds of nearby particles may fluctuate strongly. Both phenomena depend sensitively on the parameters of the system, affect collision rates and outcomes, and thus the long-term fate of the system. This is a hard problem to describe theoretically: the turbulence determines the particle paths, but at the same time the turbulent fluctuations encountered by a particle depend sensitively upon its path through the medium. In recent years it has become clear that important aspects of the particle dynamics in turbulence can be understood in terms of...

  5. Ignition of hydrogen/air mixing layer in turbulent flows

    SciTech Connect (OSTI)

    Im, H.G.; Chen, J.H. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility; Law, C.K. [Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering

    1998-03-01T23:59:59.000Z

    Autoignition of a scalar hydrogen/air mixing layer in homogeneous turbulence is studied using direct numerical simulation. An initial counterflow of unmixed nitrogen-diluted hydrogen and heated air is perturbed by two-dimensional homogeneous turbulence. The temperature of the heated air stream is chosen to be 1,100 K which is substantially higher than the crossover temperature at which the rates of the chain branching and termination reactions become equal. Three different turbulence intensities are tested in order to assess the effect of the characteristic flow time on the ignition delay. For each condition, a simulation without heat release is also performed. The ignition delay determined with and without heat release is shown to be almost identical up to the point of ignition for all of the turbulence intensities tested, and the predicted ignition delays agree well within a consistent error band. It is also observed that the ignition kernel always occurs where hydrogen is focused, and the peak concentration of HO{sub 2} is aligned well with the scalar dissipation rate. The dependence of the ignition delay on turbulence intensity is found to be nonmonotonic. For weak to moderate turbulence the ignition is facilitated by turbulence via enhanced mixing, while for stronger turbulence, whose timescale is substantially smaller than the ignition delay, the ignition is retarded due to excessive scalar dissipation, and hence diffusive loss, at the ignition location. However, for the wide range of initial turbulence fields studied, the variation in ignition delay due to the corresponding variation in turbulence intensity appears to be quite small.

  6. Experimental study of elliptical jet from sub to supercritical conditions

    SciTech Connect (OSTI)

    Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)] [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

    2014-04-15T23:59:59.000Z

    The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N{sub 2} gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

  7. Caviton dynamics in strong Langmuir turbulence

    SciTech Connect (OSTI)

    DuBois, D.; Rose, H.A.; Russell, D.

    1989-01-01T23:59:59.000Z

    Recent studies based on long time computer simulations of Langmuir turbulence as described by Zakharov's model will be reviewed. These show that for strong to moderate ion sound samping the turbulent energy is dominantly in nonlinear ''caviton'' excitations which are localized in space and time. A local caviton model will be presented which accounts for the nucleation-collapse-burnout cycles of individual cavitons as well as their space-time correlations. This model is in detailed agreement with many features of the electron density fluctuation spectra in the ionosphere modified by powerful hf waves as measured by incoherent scatter radar. Recently such observations have verified a prediction of the theory that ''free'' Langmuir waves are emitted in the caviton collapse process. These observations and theoretical considerations also strongly imply that cavitons in the heated ionosphere, under certain conditions, evolve to states in which they are ordered in space and time. The sensitivity of the high frequency Langmuir field dynamics to the low frequency ion density fluctuations and the related caviton nucleation process will be discussed. 40 refs., 19 figs.

  8. Dynamics of cavitons in strong Langmuir turbulence

    SciTech Connect (OSTI)

    DuBois, D.F.; Rose, H.A.; Russell, D.

    1990-01-01T23:59:59.000Z

    Recent studies of Langmuir turbulence as described by Zakharov's model will be reviewed. For parameters of interest in laser-plasma experiments and for ionospheric hf heating experiments a significant fraction of the turbulent energy is in nonlinear caviton'' excitations which are localized in space and time. A local caviton model will be presented which accounts for the nucleation-collapse-burnout cycles of individual cavitons as well as their space-time correlations. This model is in detailed agreement with many features of the electron density fluctuation spectra in the ionosphere modified by powerful hf waves as measured by incoherent scatter radar. Recently such observations have verified a prediction of the theory that free'' Langmuir waves are emitted in the caviton collapse process. Observations and theoretical considerations also imply that when the pump frequency is slightly lower than the ambient electron plasma frequency cavitons may evolve to states in which they are ordered in space and time. The sensitivity of the high frequency Langmuir field dynamics to the low frequency ion density fluctuations and the related caviton nucleation process will be discussed. 42 refs., 12 figs.

  9. Flame front geometry in premixed turbulent flames

    SciTech Connect (OSTI)

    Shepherd, I.G. (Lawrence Berkeley Lab., CA (United States)); Ashurst, W.T. (Sandia National Labs., Livermore, CA (United States))

    1991-12-01T23:59:59.000Z

    Experimental and numerical determinations of flame front curvature and orientation in premixed turbulent flames are presented. The experimental data is obtained from planar, cross sectional images of stagnation point flames at high Damkoehler number. A direct numerical simulation of a constant energy flow is combined with a zero-thickness, constant density flame model to provide the numerical results. The computational domain is a 32{sup 3} cube with periodic boundary conditions. The two-dimensional curvature distributions of the experiments and numerical simulations compare well at similar q{prime}/S{sub L} values with means close to zero and marked negative skewness. At higher turbulence levels the simulations show that the distributions become symmetric about zero. These features are also found in the three dimensional distributions of curvature. The simulations support assumptions which make it possible to determine the mean direction cosines from the experimental data. This leads to a reduction of 12% in the estimated flame surface area density in the middle of the flame brush. 18 refs.

  10. Anomalous scalings in differential models of turbulence

    E-Print Network [OSTI]

    Simon Thalabard; Sergey Nazarenko; Sebastien Galtier; Medvedev Sergey

    2015-02-24T23:59:59.000Z

    Differential models for hydrodynamic, passive-scalar and wave turbulence given by nonlinear first- and second-order evolution equations for the energy spectrum in the $k$-space were analysed. Both types of models predict formation an anomalous transient power-law spectra. The second-order models were analysed in terms of self-similar solutions of the second kind, and a phenomenological formula for the anomalous spectrum exponent was constructed using numerics for a broad range of parameters covering all known physical examples. The first-order models were examined analytically, including finding an analytical prediction for the anomalous exponent of the transient spectrum and description of formation of the Kolmogorov-type spectrum as a reflection wave from the dissipative scale back into the inertial range. The latter behaviour was linked to pre-shock/shock singularities similar to the ones arising in the Burgers equation. Existence of the transient anomalous scaling and the reflection-wave scenario are argued to be a robust feature common to the finite-capacity turbulence systems. The anomalous exponent is independent of the initial conditions but varies for for different models of the same physical system.

  11. Particle transport in turbulent curved pipe flow

    E-Print Network [OSTI]

    Noorani, Azad; Brandt, Luca; Schlatter, Philipp

    2015-01-01T23:59:59.000Z

    Direct numerical simulations (DNS) of particle-laden turbulent flow in straight, mildly curved and strongly bent pipes are performed in which the solid phase is modelled as small heavy spherical particles. The objective is to examine the effect of the curvature on particle transport and accumulation, in particular how the turbophoretic drift of the particles is affected by weak and strong secondary motions of the carrier phase and geometry-induced centrifugal forces. A total of seven populations of dilute particles with different Stokes numbers, one-way coupled with their carrier phase, are simulated. Even a slight non-zero curvature in the flow configuration shows a strong impact on the particle dynamics. Near-wall helicoidal particle streaks are observed in the curved configurations with their inclination varying with the strength of the secondary motion of the carrier phase. A reflection layer, as previously observed in particle laden turbulent S-shaped channels, is also apparent in the strongly curved pip...

  12. Scrape-off layer tokamak plasma turbulence

    SciTech Connect (OSTI)

    Bisai, N.; Singh, R.; Kaw, P. K. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2012-05-15T23:59:59.000Z

    Two-dimensional (2D) interchange turbulence in the scrape-off layer of tokamak plasmas and their subsequent contribution to anomalous plasma transport has been studied in recent years using electron continuity, current balance, and electron energy equations. In this paper, numerically it is demonstrated that the inclusion of ion energy equation in the simulation changes the nature of plasma turbulence. Finite ion temperature reduces floating potential by about 15% compared with the cold ion temperature approximation and also reduces the radial electric field. Rotation of plasma blobs at an angular velocity about 1.5 Multiplication-Sign 10{sup 5} rad/s has been observed. It is found that blob rotation keeps plasma blob charge separation at an angular position with respect to the vertical direction that gives a generation of radial electric field. Plasma blobs with high electron temperature gradients can align the charge separation almost in the radial direction. Influence of high ion temperature and its gradient has been presented.

  13. Leading Particle Production in Light Flavour Jets

    E-Print Network [OSTI]

    Abbiendi, G; Åkesson, P F; Alexander, Gideon; Allison, J; Anderson, K J; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Bailey, I; Ball, A H; Barberio, E; Barlow, R J; Batley, J Richard; Baumann, S; Behnke, T; Bell, K W; Bella, G; Bellerive, A; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bloodworth, Ian J; Bock, P; Böhme, J; Boeriu, O; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couchman, J; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Dallison, S; Davis, R; de Roeck, A; Dervan, P J; Desch, Klaus; Dienes, B; Dixit, M S; Donkers, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Estabrooks, P G; Etzion, E; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Feld, L; Ferrari, P; Fiedler, F; Fierro, M; Fleck, I; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Harder, K; Harel, A; Hargrove, C K; Harin-Dirac, M; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hobson, P R; Höcker, Andreas; Hoffman, K; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Jones, C R; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J I; Karapetian, G V; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klier, A; Kobayashi, T; Kobel, M; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kühl, T; Kupper, M; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lauber, J; Lawson, I; Layter, J G; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; Lillich, J; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Lü, J; Ludwig, J; Macchiolo, A; MacPherson, A L; Mader, W F; Mannelli, M; Marcellini, S; Marchant, T E; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Méndez-Lorenzo, P; Merritt, F S; Mes, H; Meyer, I; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Okpara, A N; Oreglia, M J; Orito, S; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poli, B; Polok, J; Przybycien, M B; Quadt, A; Rembser, C; Rick, Hartmut; Robins, S A; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Sproston, M; Stahl, A; Stephens, K; Stoll, K; Strom, D; Ströhmer, R; Surrow, B; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomas, J; Thomson, M A; Torrence, E; Towers, S; Trefzger, T M; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Van Kooten, R; Vannerem, P; Verzocchi, M; Voss, H; Wäckerle, F; Waller, D; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wengler, T; Wermes, N; Wetterling, D; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Zacek, V; Zer-Zion, D

    2000-01-01T23:59:59.000Z

    The energy distribution and type of the particle with the highest momentum in quark jets are determined for each of the five quark flavours making only minimal model assumptions. The analysis is based on a large statistics sample of hadronic Z0 decays collected with the OPAL detector at the LEP e+e- collider. These results provide a basis for future studies of light flavour production at other centre-of-mass energies. We use our results to study the hadronisation mechanism in light flavour jets and compare the data to the QCD models JETSET and HERWIG. Within the JETSET model we also directly determine the suppression of strange quarks to be gamma_s=0.422+-0.049 (stat.)+-0.059 (syst.) by comparing the production of charged and neutral kaons in strange and non-strange light quark events. Finally we study the features of baryon production.

  14. Phenomenology of Gamma-Ray Jets

    E-Print Network [OSTI]

    Amir Levinson

    2007-09-10T23:59:59.000Z

    We discuss some phenomenological aspects of $\\gamma$-ray emitting jets. In particular, we present calculations of the $\\gamma$-sphere and $\\pi$-sphere for various target photon fields, and employ them to demonstrate how $\\gamma$-ray observations at very high energies can be used to constraint the Doppler factor of the emitting plasma and the production of VHE neutrinos. We also consider the implications of the rapid TeV variability observed in M87 and the TeV blazars, and propose a model for the very rapid TeV flares observed with HESS and MAGIC in some blazars,that accommodates the relatively small Doppler factors inferred from radio observations. Finally, we briefly discuss the prospects for detecting VHE neutrinos from relativistic jets.

  15. Dense, vertical jet in stagnant homogeneous fluid

    E-Print Network [OSTI]

    Vergara, Ignacio

    2012-06-07T23:59:59.000Z

    30. 4 53. 2 76. 0 21. 5 37. 6 53. 7 17. 5 30. 7 41. 6 3. 1 5. 4 7. 7 G. l 10. 0 15. 4 9. 2 16. 1 21. 9 0. 16 0. 28 0. 40 0. 65 1. 13 l. 62 1. 46 2. 55 3 45 H/D 50. 0 50. 0 50. 0 25. 0 25. 0 25. 0 16. 7 16, 7 16. 7...) m D 120 80 1 m D d Jet Height(from the nozzle) Abraham Jet or nozzle diameter (slope = 1. 94) Riser height H/d 0 5 r liater depth(Tank depth) (slope 1 89) L4 ft. (1. 22 m. )] s 0 pe' H/d = 0. 333 I +Turner (slope = 1. 82) ~~ ~ (slope...

  16. Azimuthal Jet Tomography at RHIC and LHC

    E-Print Network [OSTI]

    Barbara Betz; Miklos Gyulassy

    2014-02-14T23:59:59.000Z

    A generic jet-energy loss model that is coupled to state-of-the-art hydrodynamic fields and interpolates between a wide class of running coupling pQCD-based and AdS/CFT-inspired models is compared to recent data on the azimuthal and transverse momentum dependence of high-pT pion nuclear modification factors and high-pT elliptic flow measured at RHIC and LHC. We find that RHIC data are surprisingly consistent with various scenarios considered. However, extrapolations to LHC energies favor running coupling pQCD-based models of jet-energy loss. While conformal holographic models are shown to be inconsistent with data, recent non-conformal generalizations of AdS holography may provide an alternative description.

  17. Cryogenic target formation using cold gas jets

    DOE Patents [OSTI]

    Hendricks, C.D.

    1980-02-26T23:59:59.000Z

    A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets are disclosed. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member. 4 figs.

  18. Cryogenic target formation using cold gas jets

    DOE Patents [OSTI]

    Hendricks, Charles D. [Livermore, CA

    1980-02-26T23:59:59.000Z

    A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

  19. Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators

    SciTech Connect (OSTI)

    Mastoridis, Themistoklis; /Stanford U., Elect. Eng. Dept. /SLAC

    2011-03-01T23:59:59.000Z

    The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC. Simulations studies and measurements were conducted that clearly show the correlation between RF noise and longitudinal bunch emittance, identify the major LLRF noise contributions, and determine the RF component dominating this effect. With these results, LHC upgrades and alternative algorithms are evaluated to reduce longitudinal emittance growth during operations. The applications of this work are described with regard to future machines and analysis of new technical implementations, as well as to possible future work which would continue the directions of this dissertation.

  20. On detecting oscillations of gamma rays into axion-like particles in turbulent and coherent magnetic fields

    E-Print Network [OSTI]

    Manuel Meyer; Daniele Montanino; Jan Conrad

    2014-09-04T23:59:59.000Z

    Background radiation fields pervade the Universe, and above a certain energy any $\\gamma$-ray flux emitted by an extragalactic source should be attenuated due to $e^+e^-$ pair production. The opacity could be alleviated if photons oscillated into hypothetical axion-like particles (ALPs) in ambient magnetic fields, leading to a $\\gamma$-ray excess especially at high optical depths that could be detected with imaging air Cherenkov telescopes (IACTs). Here, we introduce a method to search for such a signal in $\\gamma$-ray data and to estimate sensitivities for future observations. Different magnetic fields close to the $\\gamma$-ray source are taken into account in which photons can convert into ALPs that then propagate unimpeded over cosmological distances until they re-convert in the magnetic field of the Milky Way. Specifically, we consider the coherent field at parsec scales in a blazar jet as well as the turbulent field inside a galaxy cluster. For the latter, we explicitly derive the transversal components of a magnetic field with gaussian turbulence which are responsible for the photon-ALP mixing. To illustrate the method, we apply it to a mock IACT array with characteristics similar to the Cherenkov Telescope Array and investigate the dependence of the sensitivity to detect a $\\gamma$-ray excess on the magnetic-field parameters.

  1. Flow control via synthetic jet actuation

    E-Print Network [OSTI]

    Miller, Adam Cole

    2005-02-17T23:59:59.000Z

    4.1 Wind Tunnel Model Showing SJA Drive Through Acrylic Access Panel ..........41 4.2 Cross Section of Trailing Edge Showing Original Plenum Design .....................41 4.3 Cross Section of Trailing Edge Showing Narrow Plenum Design.... ...........................................................48 1 1. INTRODUCTION General This thesis presents a study of the effects of flow control on a NACA0015 airfoil using Synthetic Jet Actuators (SJA) at different locations along the chord. The purpose of this research was to show...

  2. NLO QCD Predictions for W+3 jets

    SciTech Connect (OSTI)

    Maitre, Daniel; /Durham U.; Berger, Carola F.; /MIT; Bern, Zvi; Febres Cordero, Fernando; Ita, Harald; Dixon, Lance J.; Forde, Darren; Gleisberg, Tanju; /UCLA /SLAC; Kosower, David; /Saclay, SPhT

    2009-12-09T23:59:59.000Z

    In this contribution we present results from the NLO computation of the production of a W boson in association with three jets in hadronic collisions. The results are obtained by combining two programs: BlackHat for the virtual one-loop matrix elements and Sherpa for the real-emission contributions. We present results for the Tevatron and the LHC, and address the issue of the choice of a common factorization and renormalization scale for this process.

  3. MAGNETIC FIELD STRUCTURES AND TURBULENT COMPONENTS IN THE STAR-FORMING MOLECULAR CLOUDS OMC-2 AND OMC-3

    SciTech Connect (OSTI)

    Poidevin, Frederick [Universidade de Sao Paulo, Instituto de Astronomia, Geofisica e CIencas Atmosfericas, Rua do Matao 1226, Butanta, Sao Paulo, SP 05508-900 (Brazil); Bastien, Pierre [Departement de Physique and Observatoire du Mont-Megantic, Universite de Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Quebec H3C 3J7 (Canada); Matthews, Brenda C., E-mail: Poidevin@astro.iag.usp.b, E-mail: Bastien@astro.umontreal.c, E-mail: brenda.matthews@nrc-cnrc.gc.c [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC (Canada)

    2010-06-20T23:59:59.000Z

    The SCUBA polarized 850 {mu}m thermal emission data of the OMC-2 region in Orion A are added to and homogeneously reduced with data already available in the OMC-3 region. The data set shows that OMC-2 is a region generally less polarized than OMC-3. Where coincident, most of the 850 {mu}m polarization pattern is similar to that measured in 350 {mu}m polarization data. Only 850 {mu}m polarimetry data have been obtained in and around MMS7, FIR1 and FIR2, and in the region south of FIR6. A realignment of the polarization vectors with the filament can be seen near FIR1 in the region south of OMC-3. An analysis shows that the energy injected by CO outflows and H{sub 2} jets associated with OMC-2 and OMC-3 does not appear to alter the polarization patterns at a scale of the 14'' resolution beam. A second-order structure function analysis of the polarization position angles shows that OMC-2 is a more turbulent region than OMC-3. OMC-3 appears to be a clear case of a magnetically dominated region with respect to the turbulence. However, for OMC-2 it is not clear that this is the case. A more in-depth analysis of five regions displayed along OMC-2/3 indicates a decrease of the mean polarization degree and an increase of the turbulent angular dispersion from north to south. A statistical analysis suggests the presence of two depolarization regimes in our maps: one regime including the effects of the cores, the other one excluding it.

  4. Study of Emission TurbulenceRadiation Interaction in Hypersonic Boundary Layers

    E-Print Network [OSTI]

    Martín, Pino

    Study of Emission Turbulence­Radiation Interaction in Hypersonic Boundary Layers L. Duan and M. P of emission turbulence­radiation interaction in hypersonic turbulent boundary layers, representative interaction between turbulence and emission at the hypersonic environment under investigation. An explanation

  5. On Measuring the Terms of the Turbulent Kinetic Energy Budget from an AUV LOUIS GOODMAN

    E-Print Network [OSTI]

    Goodman, Louis

    of production of turbulent kinetic energy (TKE). Heat flux is obtained by correlating the vertical velocityOn Measuring the Terms of the Turbulent Kinetic Energy Budget from an AUV LOUIS GOODMAN School of the steady-state, homogeneous turbulent kinetic energy budgets are obtained from mea- surements of turbulence

  6. Studies of Relativistic Jets in Active Galactic Nuclei with SKA

    E-Print Network [OSTI]

    Agudo, Ivan; Falcke, Heino; Georganopoulos, Markos; Ghisellini, Gabriele; Giovannini, Gabriele; Giroletti, Marcello; Gomez, Jose L; Gurvits, Leonid; Laing, Robert; Lister, Matthew; Marti, Jose-Maria; Meyer, Eileen T; Mizuno, Yosuke; O'Sullivan, Shane; Padovani, Paolo; Paragi, Zsolt; Perucho, Manel; Schleicher, Dominik; Stawarz, Lukasz; Vlahakis, Nektarios; Wardle, John

    2015-01-01T23:59:59.000Z

    Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. These questions will be addressed specially through analysis of the massive data sets arising from the deep, all-sky surveys (both total and polarimetric flux) from SKA1. Wide-field very-long-baseline-interferometric survey observations involving SKA1 will serve as a unique tool for distinguishing between extragalactic relativistic jets and star forming galaxies via brightness temperature measurements. Subsequent SKA1 studies of relativistic jets at different resolutions will allow for unprecedented cosmological studies of AGN jets up...

  7. Center for Turbulence Research Annual Research Briefs 2008

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    rich combustion of hydrocarbon fuels in many combustion devices: internal combustion engines, jet from combustion devices such as aircraft jet engines. Soot particles are formed and destroyed during, asthma and chronic bronchitis. Fine soot emissions (smaller than 2.5 µm) have been linked to increased

  8. COLLISIONLESS DAMPING AT ELECTRON SCALES IN SOLAR WIND TURBULENCE

    SciTech Connect (OSTI)

    TenBarge, J. M.; Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Dorland, W., E-mail: jason-tenbarge@uiowa.edu [Department of Physics, University of Maryland, College Park, MA 20742-3511 (United States)

    2013-09-10T23:59:59.000Z

    The dissipation of turbulence in the weakly collisional solar wind plasma is governed by unknown kinetic mechanisms. Two candidates have been suggested to play an important role in the dissipation, collisionless damping via wave-particle interactions and dissipation in small-scale current sheets. High resolution spacecraft measurements of the turbulent magnetic energy spectrum provide important constraints on the dissipation mechanism. The limitations of popular fluid and hybrid numerical schemes for simulation of the dissipation of solar wind turbulence are discussed, and instead a three-dimensional kinetic approach is recommended. We present a three-dimensional nonlinear gyrokinetic simulation of solar wind turbulence at electron scales that quantitatively reproduces the exponential form of the turbulent magnetic energy spectrum measured in the solar wind. A weakened cascade model that accounts for nonlocal interactions and collisionless Landau damping also quantitatively agrees with the observed exponential form. These results establish that a turbulent cascade of kinetic Alfven waves that is terminated by collisionless Landau damping is sufficient to explain the observed magnetic energy spectrum in the dissipation range of solar wind turbulence.

  9. MEASURING THE JET POWER OF FLAT-SPECTRUM RADIO QUASARS

    SciTech Connect (OSTI)

    Shabala, S. S.; Santoso, J. S. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, TAS 7001 (Australia); Godfrey, L. E. H. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

    2012-09-10T23:59:59.000Z

    We use frequency-dependent position shifts of flat-spectrum radio cores to estimate the kinetic power of active galactic nucleus (AGN) jets. We find a correlation between the derived jet powers and AGN narrow-line luminosity, consistent with the well-known relation for radio galaxies and steep spectrum quasars. This technique can be applied to intrinsically weak jets even at high redshift.

  10. Tail Emission of Prompt Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Yamazaki, R; Ioka, K; Nakamura, T; Yamazaki, Ryo; Toma, Kenji; Ioka, Kunihito; Nakamura, Takashi

    2006-01-01T23:59:59.000Z

    Tail emission of the prompt gamma-ray burst is discussed using a multiple emitting sub-shell (inhomogeneous jet, sub-jets) model. The tail is a superposition of a number of smooth, long-duration, dim, and soft pulses emitted by segments located far from the line of sight. We find that the behavior of the tail is not so much affected by the local inhomogeneity but affected by the global sub-jet distribution. Some observed tails may disfavor the power-law jets.

  11. High Multiplicity Searches at the LHC Using Jet Masses

    SciTech Connect (OSTI)

    Hook, Anson; /SLAC /Stanford U., Appl. Phys. Dept.; Izaguirre, Eder; /SLAC /Stanford U., Phys. Dept.; Lisanti, Mariangela; /Princeton U.; Wacker, Jay G.; /SLAC /Stanford U., ITP

    2012-04-24T23:59:59.000Z

    This article introduces a new class of searches for physics beyond the Standard Model that improves the sensitivity to signals with high jet multiplicity. The proposed searches gain access to high multiplicity signals by reclustering events into large-radius, or 'fat', jets and by requiring that each event has multiple massive jets. This technique is applied to supersymmetric scenarios in which gluinos are pair-produced and then subsequently decay to final states with either moderate quantities of missing energy or final states without missing energy. In each of these scenarios, the use of jet mass improves the estimated reach in gluino mass by 20% to 50% over current LHC searches.

  12. Parsec-Scale Jet-Environment Interactions in AGN

    E-Print Network [OSTI]

    Matthew L. Lister

    2007-07-12T23:59:59.000Z

    Observations made with the VLBA have led to fundamental advances in our understanding of how radio jets in AGN evolve from parsec-scales out to distances exceeding several hundred kiloparsecs. In this review I discuss current models of young radio source evolution, as well as the observational evidence for a rapid change in jet properties on scales of ~1 kpc. A central topic of current debate is the relative importance of intermittent jet fueling versus jet-environment interactions in causing a drop-off in powerful radio sources at this critical evolutionary stage. Recent 3-D hydrodynamical jet simulations suggest that dense environments and cloud collisions can temporarily stifle, but not completely halt powerful relativistic jets. Several VLBA studies of jet-ISM interactions in both blazars and weak Seyfert jets have indicated that collimated outflows are indeed possible in dense environments. At present, the bulk of the evidence favors intermittent AGN accretion as the dominant factor in determining the evolutionary path of large numbers of AGN jets.

  13. Infrared imaging results of an excited planar jet

    SciTech Connect (OSTI)

    Farrington, R.B.

    1991-12-01T23:59:59.000Z

    Planar jets are used for many applications including heating, cooling, and ventilation. Generally such a jet is designed to provide good mixing within an enclosure. In building applications, the jet provides both thermal comfort and adequate indoor air quality. Increased mixing rates may lead to lower short-circuiting of conditioned air, elimination of dead zones within the occupied zone, reduced energy costs, increased occupant comfort, and higher indoor air quality. This paper discusses using an infrared imaging system to show the effect of excitation of a jet on the spread angle and on the jet mixing efficiency. Infrared imaging captures a large number of data points in real time (over 50,000 data points per image) providing significant advantages over single-point measurements. We used a screen mesh with a time constant of approximately 0.3 seconds as a target for the infrared camera to detect temperature variations in the jet. The infrared images show increased jet spread due to excitation of the jet. Digital data reduction and analysis show change in jet isotherms and quantify the increased mixing caused by excitation. 17 refs., 20 figs.

  14. Environmental and economic assessment of microalgae-derived jet fuel

    E-Print Network [OSTI]

    Carter, Nicholas Aaron

    2012-01-01T23:59:59.000Z

    Significant efforts must be undertaken to quantitatively assess various alternative jet fuel pathways when working towards achieving environmental and economic United States commercial and military alternative aviation ...

  15. Inclusive-jet photoproduction at HERA and determination of alphas

    E-Print Network [OSTI]

    ZEUS Collaboration; H. Abramowicz; I. Abt; L. Adamczyk; M. Adamus; R. Aggarwal; S. Antonelli; P. Antonioli; A. Antonov; M. Arneodo; V. Aushev; Y. Aushev; O. Bachynska; A. Bamberger; A. N. Barakbaev; G. Barbagli; G. Bari; F. Barreiro; N. Bartosik; D. Bartsch; M. Basile; O. Behnke; J. Behr; U. Behrens; L. Bellagamba; A. Bertolin; S. Bhadra; M. Bindi; C. Blohm; V. Bokhonov; T. Bold; K. Bondarenko; E. G. Boos; K. Borras; D. Boscherini; D. Bot; I. Brock; E. Brownson; R. Brugnera; N. Brummer; A. Bruni; G. Bruni; B. Brzozowska; P. J. Bussey; B. Bylsma; A. Caldwell; M. Capua; R. Carlin; C. D. Catterall; S. Chekanov; J. Chwastowski; J. Ciborowski; R. Ciesielski; L. Cifarelli; F. Cindolo; A. Contin; A. M. Cooper-Sarkar; N. Coppola; M. Corradi; F. Corriveau; M. Costa; G. D'Agostini; F. Dal Corso; J. del Peso; R. K. Dementiev; S. De Pasquale; M. Derrick; R. C. E. Devenish; D. Dobur; B. A. Dolgoshein; G. Dolinska; A. T. Doyle; V. Drugakov; L. S. Durkin; S. Dusini; Y. Eisenberg; P. F. Ermolov; A. Eskreys; S. Fang; S. Fazio; J. Ferrando; M. I. Ferrero; J. Figiel; M. Forrest; B. Foster; G. Gach; A. Galas; E. Gallo; A. Garfagnini; A. Geiser; I. Gialas; A. Gizhko; L. K. Gladilin; D. Gladkov; C. Glasman; O. Gogota; Yu. A. Golubkov; P. Gottlicher; I. Grabowska-Bold; J. Grebenyuk; I. Gregor; G. Grigorescu; G. Grzelak; O. Gueta; M. Guzik; C. Gwenlan; T. Haas; W. Hain; R. Hamatsu; J. C. Hart; H. Hartmann; G. Hartner; E. Hilger; D. Hochman; R. Hori; K. Horton; A. Huttmann; Z. A. Ibrahim; Y. Iga; R. Ingbir; M. Ishitsuka; H. -P. Jakob; F. Januschek; T. W. Jones; M. Jungst; I. Kadenko; B. Kahle; S. Kananov; T. Kanno; U. Karshon; F. Karstens; I. I. Katkov; M. Kaur; P. Kaur; A. Keramidas; L. A. Khein; J. Y. Kim; D. Kisielewska; S. Kitamura; R. Klanner; U. Klein; E. Koffeman; N. Kondrashova; O. Kononeko; P. Kooijman; Ie. Korol; I. A. Korzhavina; A. Kotanski; U. Kotz; H. Kowalski; O. Kuprash; M. Kuze; A. Lee; B. B. Levchenko; A. Levy; V. Libov; S. Limentani; T. Y. Ling; M. Lisovyi; E. Lobodzinska; W. Lohmann; B. Lohr; E. Lohrmann; K. R. Long; A. Longhin; D. Lontkovskyi; O. Yu. Lukina; J. Maeda; S. Magill; I. Makarenko; J. Malka; R. Mankel; A. Margotti; G. Marini; J. F. Martin; A. Mastroberardino; M. C. K. Mattingly; I. -A. Melzer-Pellmann; S. Mergelmeyer; S. Miglioranzi; F. Mohamad Idris; V. Monaco; A. Montanari; J. D. Morris; K. Mujkic; B. Musgrave; K. Nagano; T. Namsoo; R. Nania; A. Nigro; Y. Ning; T. Nobe; U. Noor; D. Notz; R. J. Nowak; A. E. Nuncio-Quiroz; B. Y. Oh; N. Okazaki; K. Oliver; K. Olkiewicz; Yu. Onishchuk; K. Papageorgiu; A. Parenti; E. Paul; J. M. Pawlak; B. Pawlik; P. G. Pelfer; A. Pellegrino; W. Perlanski; H. Perrey; K. Piotrzkowski; P. Plucinski; N. S. Pokrovskiy; A. Polini; A. S. Proskuryakov; M. Przybycien; A. Raval; D. D. Reeder; B. Reisert; Z. Ren; J. Repond; Y. D. Ri; A. Robertson; P. Roloff; I. Rubinsky; M. Ruspa; R. Sacchi; U. Samson; G. Sartorelli; A. A. Savin; D. H. Saxon; M. Schioppa; S. Schlenstedt; P. Schleper; W. B. Schmidke; U. Schneekloth; V. Schonberg; T. Schorner-Sadenius; J. Schwartz; F. Sciulli; L. M. Shcheglova; R. Shehzadi; S. Shimizu; I. Singh; I. O. Skillicorn; W. Slominski; W. H. Smith; V. Sola; A. Solano; D. Son; V. Sosnovtsev; A. Spiridonov; H. Stadie; L. Stanco; N. Stefaniuk; A. Stern; T. P. Stewart; A. Stifutkin; P. Stopa; S. Suchkov; G. Susinno; L. Suszycki; J. Sztuk-Dambietz; D. Szuba; J. Szuba; A. D. Tapper; E. Tassi; J. Terron; T. Theedt; H. Tiecke; K. Tokushuku; J. Tomaszewska; V. Trusov; T. Tsurugai; M. Turcato; O. Turkot; T. Tymieniecka; M. Vazquez; A. Verbytskyi; O. Viazlo; N. N. Vlasov; R. Walczak; W. A. T. Wan Abdullah; J. J. Whitmore; L. Wiggers; M. Wing; M. Wlasenko; G. Wolf; H. Wolfe; K. Wrona; A. G. Yagues-Molina; S. Yamada; Y. Yamazaki; R. Yoshida; C. Youngman; O. Zabiegalov; A. F. Zarnecki; L. Zawiejski; O. Zenaiev; W. Zeuner; B. O. Zhautykov; N. Zhmak; C. Zhou; A. Zichichi; Z. Zolkapli; D. S. Zotkin

    2012-05-28T23:59:59.000Z

    Inclusive-jet cross sections have been measured in the reaction ep->e+jet+X for photon virtuality Q2 energies in the region 142 energy, ETjet, and pseudorapidity, etajet, for jets with ETjet > 17 GeV and -1 energy-scale dependence of the coupling was determined. The value of alphas(Mz) extracted from the measurements based on the kT jet algorithm is alphas(Mz) = 0.1206 +0.0023 -0.0022 (exp.) +0.0042 -0.0035 (th.); the results from the anti-kT and SIScone algorithms are compatible with this value and have a similar precision.

  16. Microhole Arrays Drilled With Advanced Abrasive Slurry Jet Technology...

    Open Energy Info (EERE)

    Arrays Drilled With Advanced Abrasive Slurry Jet Technology To Efficiently Exploit Enhanced Geothermal Systems Geothermal Project Jump to: navigation, search Last modified on July...

  17. An alternative model of jet suppression at RHIC energies

    E-Print Network [OSTI]

    Roman Lietava; Jan Pisut; Neva Pisutova; Boris Tomasik

    2003-02-10T23:59:59.000Z

    We propose a simple Glauber-type mechanism for suppression of jet production up to transverse momenta of about 10 GeV/c at RHIC. For processes in this kinematic region, the formation time is smaller than the interval between two successive hard partonic collisions and the subsequent collision influences the jet production. Number of jets then roughly scales with the number of participants. Proportionality to the number of binary collisions is recovered for very high transverse momenta. The model predicts suppression of jet production in d+Au collisions at RHIC.

  18. Geographic Area Month Aviation Gasoline Kerosene-Type Jet Fuel

    Gasoline and Diesel Fuel Update (EIA)

    State (Cents per Gallon Excluding Taxes) - Continued Geographic Area Month Aviation Gasoline Kerosene-Type Jet Fuel Kerosene Sales to End Users Sales for Resale Sales to End...

  19. COLLIMATION AND CONFINEMENT OF MAGNETIC JETS BY EXTERNAL MEDIA

    SciTech Connect (OSTI)

    Levinson, Amir [School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)] [School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Begelman, Mitchell C., E-mail: Levinson@wise.tau.ac.il, E-mail: mitch@jila.colorado.edu [JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, CO 80309-0440 (United States)

    2013-02-20T23:59:59.000Z

    We study the collimation of a highly magnetized jet by a surrounding cocoon that forms as a result of the interaction of the jet with the external medium. We show that in regions where the jet is well confined by the cocoon, current-driven instabilities should develop over timescales shorter than the expansion time of the jet's head. We speculate that these instabilities would give rise to complete magnetic field destruction, whereby the jet undergoes a transition from high to low sigma above the collimation zone. Using this assumption, we construct a self-consistent model for the evolution of the jet-cocoon system in an ambient medium of arbitrary density profile. We apply the model to jet breakout in long gamma-ray bursts (GRBs) and show that the jet is highly collimated inside the envelope of the progenitor star and is likely to remain confined well after breakout. We speculate that this strong confinement may provide a channel for magnetic field conversion in GRB outflows, whereby the hot, low-sigma jet section thereby produced is the source of the photospheric emission observed in many bursts.

  20. asian jet stream: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laboratory Kidston, Joseph 11 Rayleigh Wave-Internal Wave Coupling and Internal Wave Generation Above a Model Jet Stream Mathematics Websites Summary: Rayleigh...

  1. Measurement of b-quark Jet Shapes at CDF

    SciTech Connect (OSTI)

    Lister, Alison; /Zurich, ETH

    2006-03-01T23:59:59.000Z

    The main topic of this thesis is the measurement of b-quark jet shapes at CDF. CDF is an experiment located at Fermilab, in the United States, which studies proton-antiproton collisions at a center of mass energy of 1.96TeV. To reach this energy, the particles are accelerated using the Tevatron accelerator which is currently the highest energy collider in operation. The data used for this analysis were taken between February 2002 and September 2004 and represent an integrated luminosity of about 300 pb{sup -1}. This is the first time that b-quark jet shapes have been measured at hadron colliders. The basis of this measurement lies in the possibility of enhancing the b-quark jet content of jet samples by requiring the jets to be identified as having a displaced vertex inside the jet cone. Such jets are called tagged. This enhances the b-quark jet fraction from about 5% before tagging to 20-40% after tagging, depending on the transverse momentum of the jets. I verified that it is possible to apply this secondary vertex tagging algorithm to different cone jet algorithms (MidPoint and JetClu) and different cone sizes (0.4 and 0.7). I found that the performance of the algorithm does not change significantly, as long as the sub-cone inside which tracks are considered for the tagging is kept at the default value of 0.4. Because the b-quark purity of the jets is still relatively low, it is necessary to extract the shapes of b-quark jets in a statistical manner from the jet shapes both before and after tagging. The other parameters that enter into the unfolding equation used to extract the b-quark jet shapes are the b-jet purities, the biases due to the tagging requirement both for b- and nonbjets and the hadron level corrections. The last of these terms corrects the measured b-jet shapes back to the shapes expected at hadron level which makes comparisons with theoretical models and other experimental results possible. This measurement shows that, despite relatively large systematic uncertainties, the measured b-quark jet shapes are significantly different from those expected from the so-called Pythia Tune A Monte Carlo simulation, the most widely used Leading Order Monte Carlo model at CDF. This difference can be mostly attributed to the fact that the fraction of b-quark jets that originate from flavour creation (where a single b-quark is expected inside the same jet cone) over those that originate from gluon splitting (where two b-quarks are expected to be inside the same jet cone) is slightly different in the Pythia Tune A Monte Carlo predictions than in data. This measurement can help in the tuning of the fraction of gluon splitting to flavour creation b-quark jets in the Monte Carlo simulation. This tuning is particularly important for the extrapolation up to LHC energies where many searches will involve b-quark jets. During the first year of my thesis work, I worked on the implementation of a prototype detector control system for the electromagnetic calorimeter which is being built for the CMS experiment at CERN. The prototype which I implemented was used to monitor and control the high voltage, low voltage, cooling and precision temperature monitoring systems during the summer 2003 test-beam. This was one of the first, almost complete, systems implemented and used by an LHC experiment for test-beam monitoring.

  2. Edge Turbulence Velocity Changes with Lithium Coating on NSTX

    SciTech Connect (OSTI)

    Cao, A.; Zweben, S. J.; Stotler, D. P.; Bell, M.; Diallo, A.; Kaye, S. M.; LeBlanc, B.

    2012-08-10T23:59:59.000Z

    Lithium coating improves energy confinement and eliminates edge localized modes in NSTX, but the mechanism of this improvement is not yet well understood. We used the gas-puff-imaging (GPI) diagnostic on NSTX to measure the changes in edge turbulence which occurred during a scan with variable lithium wall coating, in order to help understand the reason for the confinement improvement with lithium. There was a small increase in the edge turbulence poloidal velocity and a decrease in the poloidal velocity fluctuation level with increased lithium. The possible effect of varying edge neutral density on turbulence damping was evaluated for these cases in NSTX. __________________________________________________

  3. Compressive turbulent cascade and heating in the solar wind

    SciTech Connect (OSTI)

    Marino, R. [Dipartimento di Fisica, Universita della Calabria, Ponte Bucci 31C, I-87036 Rende (Italy); University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France); Sorriso-Valvo, L. [Liquid Crystal Laboratory, INFM/CNR, Ponte Bucci 33B, I-87036 Rende (Italy); Carbone, V. [Dipartimento di Fisica, Universita della Calabria, Ponte Bucci 31C, I-87036 Rende (Italy); Noullez, A. [University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France); Bruno, R. [INAF-Istituto Fisica Spazio Interplanetario, Rome (Italy)

    2010-03-25T23:59:59.000Z

    A turbulent energy cascade has been recently identified in high-latitude solar wind data samples by using a Yaglom-like relation. However, analogous scaling law, suitably modified to take into account compressible fluctuations, has been observed in a much more extended fraction of the same data set recorded by the Ulysses spacecraft. Thus, it seems that large scale density fluctuations, despite their low amplitude, play a major role in the basic scaling properties of turbulence. The compressive turbulent cascade, moreover, seems to be able to supply the energy needed to account for the local heating of the non-adiabatic solar wind.

  4. Nonextensive statistical dynamics applied to wall turbulence

    E-Print Network [OSTI]

    Simen Å Ellingsen; Per-Åge Krogstad

    2014-02-10T23:59:59.000Z

    We apply a formalism of nonextensive statistical mechanics to experimental wall turbulence data, for the first time to our knowledge. Wind tunnel data for velocity differences a streamwise distance $r$ apart are compared to the prediction from theory as developed by Beck. The simplest theory, in which all free parameters are removed, is found to reproduce statistics for the wall-normal velocity component remarkably well, even for $r$ well beyond the corresponding integral scale, while the corresponding description of the streamwise velocity fluctuations is reasonable at separations below the integral scale. A least-squares 2-parameter fit is performed, and the dependence of the optimum parameter values on wall separation and $r$ is analysed. Both parameters are found to be approximately independent of wall-separation in the logarithmic sub-layer.

  5. Nonlinear parallel momentum transport in strong turbulence

    E-Print Network [OSTI]

    Wang, Lu; Diamond, P H

    2015-01-01T23:59:59.000Z

    Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the \\emph{nonlinear} momentum flux-$$. However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas {\\bf 18}, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong turbulence is calculated by using three dimensional Hasegawa-Mima equation. It is shown that nonlinear diffusivity is smaller than quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so could be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.

  6. Generation and Propagation of Inertia Gravity Waves from Vortex Dipoles and Jets Shuguang Wang

    E-Print Network [OSTI]

    Generation and Propagation of Inertia Gravity Waves from Vortex Dipoles and Jets Shuguang Wang generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model, moist convection, fronts, upper level jets, geostrophic adjustment and spontaneous generation (Fritts

  7. Quantitative imaging of turbulent and reacting flows

    SciTech Connect (OSTI)

    Paul, P.H. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01T23:59:59.000Z

    Quantitative digital imaging, using planar laser light scattering techniques is being developed for the analysis of turbulent and reacting flows. Quantitative image data, implying both a direct relation to flowfield variables as well as sufficient signal and spatial dynamic range, can be readily processed to yield two-dimensional distributions of flowfield scalars and in turn two-dimensional images of gradients and turbulence scales. Much of the development of imaging techniques to date has concentrated on understanding the requisite molecular spectroscopy and collision dynamics to be able to determine how flowfield variable information is encoded into the measured signal. From this standpoint the image is seen as a collection of single point measurements. The present effort aims at realizing necessary improvements in signal and spatial dynamic range, signal-to-noise ratio and spatial resolution in the imaging system as well as developing excitation/detection strategies which provide for a quantitative measure of particular flowfield scalars. The standard camera used for the study is an intensified CCD array operated in a conventional video format. The design of the system was based on detailed modeling of signal and image transfer properties of fast UV imaging lenses, image intensifiers and CCD detector arrays. While this system is suitable for direct scalar imaging, derived quantities (e.g. temperature or velocity images) require an exceptionally wide dynamic range imaging detector. To apply these diagnostics to reacting flows also requires a very fast shuttered camera. The authors have developed and successfully tested a new type of gated low-light level detector. This system relies on fast switching of proximity focused image-diode which is direct fiber-optic coupled to a cooled CCD array. Tests on this new detector show significant improvements in detection limit, dynamic range and spatial resolution as compared to microchannel plate intensified arrays.

  8. Robust circularly polarized few-optical-cycle solitons in Kerr media

    SciTech Connect (OSTI)

    Leblond, Herve; Sanchez, Francois [Laboratoire de Photonique d'Angers, EA 4464, Universite d'Angers, 2 Bd. Lavoisier, FR-49045 Angers Cedex 01 (France); Triki, Houria [Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, P.O. Box 12, DZ-23000 Annaba (Algeria); Mihalache, Dumitru [Laboratoire de Photonique d'Angers, EA 4464, Universite d'Angers, 2 Bd. Lavoisier, FR-49045 Angers Cedex 01 (France); Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, Magurele-Bucharest, RO-077125 (Romania); Academy of Romanian Scientists, 54 Splaiul Independentei, Bucharest RO-050094 (Romania)

    2011-06-15T23:59:59.000Z

    We consider the propagation of circularly polarized few-cycle pulses (FCPs) in Kerr media beyond the slowly varying envelope approximation. Assuming that the frequency of the transition is far above the characteristic wave frequency (long-wave-approximation regime), we show that propagation of FCPs, taking into account the wave polarization, is described by the nonintegrable complex modified Korteweg-de Vries (cmKdV) equation. By direct numerical simulations, we get robust localized solutions to the cmKdV equation, which describe circularly polarized few-cycle-optical solitons and strongly differ from the breather soliton of the modified Korteweg-de Vries equation, which represents linearly polarized FCP solitons. The circularly polarized FCP soliton becomes unstable when the angular frequency is less than 1.5 times the inverse of the pulse length. The unstable subcycle pulses decay into linearly polarized half-cycle pulses, the polarization direction of which slowly rotates around the propagation axis.

  9. Interaction of a circularly polarised gravitational wave with a charged particle in a static magnetic background

    E-Print Network [OSTI]

    Sunandan Gangopadhyay; Anirban Saha; Swarup Saha

    2014-12-24T23:59:59.000Z

    Interaction of a charged particle in a static magnetic background, i.e., a Landau system with circularly polarised gravitational wave (GW) is studied quantum mechanically in the long wavelength and low velocity limit. We quantize the classical Hamiltonian following \\cite{speli}. The rotating polarization vectors of the circularly polarized GW are employed to form a unique directional triad which served as the coordinate axes. The Schrodinger equations for the system are cast in the form of a set of coupled linear differential equations. This system is solved by iterative technique. We compute the time-evolution of the position and momentum expectation values of the particle. The results show that the resonance behaviour obtained earlier\\cite{emgw_classical} by classical treatements of the system has a quantum analogue not only for the linearly polarized GW \\cite{emgw_1_lin}, but for circularly polarized GW as well.

  10. Laser photons acquire circular polarization by interacting with a Dirac or Majorana neutrino beam

    E-Print Network [OSTI]

    Rohoollah Mohammadi; She-Sheng Xue

    2014-03-14T23:59:59.000Z

    It is shown that for the reason of neutrinos being left-handed and their gauge-couplings being parity-violated, linearly polarized photons acquire their circular polarization by interacting with neutrinos. Calculating the ratio of linear and circular polarizations of laser photons interacting with either Dirac or Majorana neutrino beam, we obtain this ratio for the Dirac neutrino case, which is about twice less than the ratio for the Majorana neutrino case. Based on this ratio, we discuss the possibility of using advanced laser facilities and the T2K neutrino experiment to measure the circular polarization of laser beams interacting with neutrino beams in ground laboratories. This could be an additional and useful way to gain some insight into the physics of neutrinos, for instance their Dirac or Majorana nature.

  11. PowerJet Wind Turbine Project

    SciTech Connect (OSTI)

    Bartlett, Raymond J

    2008-11-30T23:59:59.000Z

    PROJECT OBJECTIVE The PowerJet wind turbine overcomes problems characteristic of the small wind turbines that are on the market today by providing reliable output at a wide range of wind speeds, durability, silent operation at all wind speeds, and bird-safe operation. Prime Energy�s objective for this project was to design and integrate a generator with an electrical controller and mechanical controls to maximize the generation of electricity by its wind turbine. The scope of this project was to design, construct and test a mechanical back plate to control rotational speed in high winds, and an electronic controller to maximize power output and to assist the base plate in controlling rotational speed in high winds. The test model will continue to operate beyond the time frame of the project, with the ultimate goal of manufacturing and marketing the PowerJet worldwide. Increased Understanding of Electronic & Mechanical Controls Integrated With Electricity Generator The PowerJet back plate begins to open as wind speed exceeds 13.5 mps. The pressure inside the turbine and the turbine rotational speed are held constant. Once the back plate has fully opened at approximately 29 mps, the controller begins pulsing back to the generator to limit the rotational speed of the turbine. At a wind speed in excess of 29 mps, the controller shorts the generator and brings the turbine to a complete stop. As the wind speed subsides, the controller releases the turbine and it resumes producing electricity. Data collection and instrumentation problems prevented identification of the exact speeds at which these events occur. However, the turbine, controller and generator survived winds in excess of 36 mps, confirming that the two over-speed controls accomplished their purpose. Technical Effectiveness & Economic Feasibility Maximum Electrical Output The output of electricity is maximized by the integration of an electronic controller and mechanical over-speed controls designed and tested during the course of this project. The output exceeds that of the PowerJet�s 3-bladed counterparts (see Appendix). Durability All components of the PowerJet turbine assembly�including the electronic and mechanical controls designed, manufactured and field tested during the course of this project�proved to be durable through severe weather conditions, with constant operation and no interruption in energy production. Low Cost Materials for the turbine, generator, tower, charge controllers and ancillary parts are available at reasonable prices. Fabrication of these parts is also readily available worldwide. The cost of assembling and installing the turbine is reduced because it has fewer parts and requires less labor to manufacture and assemble, making it competitively priced compared with turbines of similar output manufactured in the U.S. and Europe. The electronic controller is the unique part to be included in the turbine package. The controllers can be manufactured in reasonably-sized production runs to keep the cost below $250 each. The data logger and 24 sensors are for research only and will be unnecessary for the commercial product. Benefit To Public The PowerJet wind-electric system is designed for distributed wind generation in 3 and 4 class winds. This wind turbine meets DOE�s requirements for a quiet, durable, bird-safe turbine that eventually can be deployed as a grid-connected generator in urban and suburban settings. Results As described more fully below and illustrated in the Appendices, the goals and objectives outlined in 2060 SOPO were fully met. Electronic and mechanical controls were successfully designed, manufactured and integrated with the generator. The turbine, tower, controllers and generators operated without incident throughout the test period, surviving severe winter and summer weather conditions such as extreme temperatures, ice and sustained high winds. The electronic controls were contained in weather-proof electrical boxes and the elec

  12. Coherent Structures in Turbulent Flows: Experimental Studies on the Turbulence of Multiphase Plumes and Tidal Vortices

    E-Print Network [OSTI]

    Bryant, Duncan Burnette

    2011-08-08T23:59:59.000Z

    Width viii wb Slip Velocity x Horizontal Direction y Vertical Direction ? Entrainment Coefficient ? Circulation ?E Circulation in Boundary Layer ?S Starting-jet Circulation ? Boundary Layer Width ? Dissipation ? Kolmogorov Length Scale... representing the plume center and the dotted line marking the plume edge in subplot (b) ................................................ 28 2.7 Example of the vortex circulation (a) and enstrophy (b) versus position in the plume for a single velocity...

  13. Discreteness and resolution effects in rapidly rotating turbulence

    E-Print Network [OSTI]

    Bourouiba, Lydia

    Rotating turbulence is characterized by the nondimensional Rossby number Ro, which is a measure of the strength of the Coriolis term relative to that of the nonlinear term. For rapid rotation (Ro?0), nonlinear interactions ...

  14. Cross-Scale Effects in Solar-Wind Turbulence

    SciTech Connect (OSTI)

    Valentini, F.; Veltri, P. [Dipartimento di Fisica and CNISM, Universita della Calabria, 87036 Rende (Serbia and Montenegro) (Italy); Califano, F. [Dipartimento di Fisica and CNISM, Universita di Pisa, 56127 Pisa (Italy); Mangeney, A. [Observatoire de Paris-Meudon, 92195 Meudon Cedex (France)

    2008-07-11T23:59:59.000Z

    The understanding of the small-scale termination of the turbulent energy cascade in collisionless plasmas is nowadays one of the outstanding problems in space physics. In the absence of collisional viscosity, the dynamics at small scales is presumably kinetic in nature; the identification of the physical mechanism which replaces energy dissipation and establishes the link between macroscopic and microscopic scales would open a new scenario in the study of turbulent heating in space plasmas. We present a numerical analysis of kinetic effects along the turbulent energy cascade in solar-wind plasmas which provides an effective unified interpretation of a wide set of spacecraft observations and shows that, simultaneously with an increase in the ion perpendicular temperature, strong bursts of electrostatic activity in the form of ion-acoustic turbulence are produced together with accelerated beams in the ion distribution function.

  15. Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast uncertainty

    E-Print Network [OSTI]

    Ross, Shane

    Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast structures Stochastic trajectory Stochastic FTLE field Ensemble forecasting Uncertainty analysis a b s t r of the forecast FTLE fields is analyzed using ensemble forecasting. Unavoidable errors of the forecast velocity

  16. Experimental Signatures of Critically Balanced Turbulence in MAST

    E-Print Network [OSTI]

    Ghim, Y.-c.

    Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, ...

  17. Test particle study of ion transport in drift type turbulence

    SciTech Connect (OSTI)

    Vlad, M.; Spineanu, F. [National Institute of Laser, Plasma and Radiation Physics, Association EURATOM-MEdC, Atomistilor 409, 077125 Magurele, Bucharest (Romania)] [National Institute of Laser, Plasma and Radiation Physics, Association EURATOM-MEdC, Atomistilor 409, 077125 Magurele, Bucharest (Romania)

    2013-12-15T23:59:59.000Z

    Ion transport regimes in drift type turbulence are determined in the frame of a realistic model for the turbulence spectrum based on numerical simulations. The model includes the drift of the potential with the effective diamagnetic velocity, turbulence anisotropy, and dominant waves. The effects of the zonal flow modes are also analyzed. A semi-analytical method that is able to describe trajectory stochastic trapping or eddying is used for obtaining the transport coefficients as function of the parameters of the turbulence. Analytical approximations of the transport coefficients are derived from the results. They show the transition from Bohm to gyro-Bohm scaling as plasma size increases in very good agreement with the numerical simulations.

  18. Behavior of buoyant moist plumes in turbulent atmospheres

    E-Print Network [OSTI]

    Hamza, Redouane

    1981-01-01T23:59:59.000Z

    A widely applicable computational model of buoyant moist plumes in turbulent atmospheres has been constructed. To achieve this a one dimensional Planetary Boundary Layer (P.B.L.) model has been developed to account for ...

  19. Turbulent drag reduction by constant near-wall forcing

    E-Print Network [OSTI]

    JIN XU, SUCHUAN DONG, MARTIN R. MAXEY and GEORGE E. KARNIADAKIS

    2007-06-07T23:59:59.000Z

    Injection of high molecular weight polymer solutions or gas in the near-wall region of a liquid boundary layer can result in turbulent drag reduction of more than ...

  20. Water Vapor Turbulence Statistics in the Convective Boundary...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    This study presented the first long-term data set of variance and skewness turbulent statistic profiles in the CBL, spanning a range of seasons and environmental conditions. These...