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Sample records for turbulent circular jet

  1. Large-eddy simulation of turbulent circular jet flows

    SciTech Connect (OSTI)

    Jones, S. C.; Sotiropoulos, F.; Sale, M. J.

    2002-07-01

    This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energy’s Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.

  2. Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection

    E-Print Network [OSTI]

    Abdou, Mohamed

    Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline ion inertial fusion reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive observations and quantitative data for rectangular and circular jets are compared in an effort to illuminate

  3. Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection

    E-Print Network [OSTI]

    California at Los Angeles, University of

    Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive beam line components from for rectangular and circular jets are compared in an effort to illuminate the critical phenomena involved

  4. Turbulent Jets SUMMARY: This chapter is concerned with turbulent jets, namely their overall

    E-Print Network [OSTI]

    Cushman-Roisin, Benoit

    Chapter 9 Turbulent Jets SUMMARY: This chapter is concerned with turbulent jets, namely their overall shape and velocity structure. The first jets being considered are those penetrating in homogeneous terminology. Continuous Intermittent injection injection Momentum only Jet Puff Buoyancy only Plume Thermal

  5. Turbulent round jet under gravity waves 

    E-Print Network [OSTI]

    Ryu, Yong Uk

    2002-01-01

    The behavior of a neutrally buoyant horizontal turbulent round jet under a wavy environment was investigated. Progressive waves with different wave amplitudes in an intermediate water depth were used. The Particle Image Velocimetry (PIV) technique...

  6. The turbulent/non-turbulent interface at the outer boundary of a self-similar turbulent jet

    E-Print Network [OSTI]

    Hunt, Julian

    The turbulent/non-turbulent interface at the outer boundary of a self-similar turbulent jet J-similar turbulent jet at Re=2·103 is investigated ex- perimentally by means of combined particle image velo- cimetry (PIV) laser-induced fluorescence (LIF) measurements. The jet fluid contains a fluorescent dye so

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

    E-Print Network [OSTI]

    Potts, Dennis Wayne

    1984-01-01

    profile for U = 550 ft/s, x/d = 30 (radial 2) 1 30 85 Wall jet turbulence profile for U = 550 ft/s, x/d = 30 ( radial 4) 131 86 Wall jet turbulence profile for Uo5 50 f t/ s, x/ d= 30(ax i al rad i al ) 132 Spread r ate of the wall jet along the axis... of the cylinder a compar ed to a flat plate . . . . 140 95 Velocity scale of the wall jet for U = 400 ft/s, x/d = 7 141 96 Velocity scale of the wall jet for U = 400 ft/s, x/d = 15 142 97 Velocity scale of tne wall jet for Uo 4 0 0 f t / s x / d 3 0 143 9S...

  8. Spark ignition of lifted turbulent jet flames

    SciTech Connect (OSTI)

    Ahmed, S.F.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2006-07-15

    This paper presents experiments on ignition and subsequent edge flame propagation in turbulent nonpremixed methane jets in air. The spark position, energy, duration, electrode diameter and gap, and the jet velocity and air premixing of the fuel stream are examined to study their effects on the ignition probability defined as successful flame establishment. The flame is visualized by a high-speed camera and planar laser-induced fluorescence of OH. It was found that after an initially spherical shape, the flame took a cylindrical shape with a propagating edge upstream. The probability of successful ignition increases with high spark energy, thin electrode diameter and wide gap, but decreases with increasing dilution of the jet with air. The flame kernel growth rate is high when the ignition probability is high for all parameters, except for jet velocity. Increasing the jet velocity decreases the ignition probability at all locations. The average flame position as a function of time from the spark was measured and the data were used to estimate a net propagation speed, which then resulted in an estimate of the average edge flame speed relative to the incoming flow. This was about 3 to 6 laminar burning velocities of a stoichiometric mixture. The measurements can assist theoretical models for the probability of ignition of nonpremixed flames and for edge flame propagation in turbulent inhomogeneous mixtures, both of which determine the success of ignition in practical combustion systems. (author)

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

    E-Print Network [OSTI]

    Robi Banerjee; Ralf S. Klessen; Christian Fendt

    2007-06-25

    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.

  10. The deterministic chaos and random noise in turbulent jet

    SciTech Connect (OSTI)

    Yao, Tian-Liang; Liu, Hai-Feng Xu, Jian-Liang; Li, Wei-Feng

    2014-06-01

    A turbulent flow is usually treated as a superposition of coherent structure and incoherent turbulence. In this paper, the largest Lyapunov exponent and the random noise in the near field of round jet and plane jet are estimated with our previously proposed method of chaotic time series analysis [T. L. Yao, et al., Chaos 22, 033102 (2012)]. The results show that the largest Lyapunov exponents of the round jet and plane jet are in direct proportion to the reciprocal of the integral time scale of turbulence, which is in accordance with the results of the dimensional analysis, and the proportionality coefficients are equal. In addition, the random noise of the round jet and plane jet has the same linear relation with the Kolmogorov velocity scale of turbulence. As a result, the random noise may well be from the incoherent disturbance in turbulence, and the coherent structure in turbulence may well follow the rule of chaotic motion.

  11. Numerical simulation of vortical flows in the near field of jets from notched circular nozzles

    E-Print Network [OSTI]

    Liu, Feng

    Numerical simulation of vortical flows in the near field of jets from notched circular nozzles Keywords: Jet Vortex Computational fluid dynamics Direct numerical simulation Non-circular nozzles a b s t r a c t The vortex dominated flows in the near field of jets from notched circular nozzles

  12. Implicit LES Simulation of Two phase Turbulent Jet Flow

    E-Print Network [OSTI]

    McDonald, Kirk

    Implicit LES Simulation of Two phase Turbulent Jet Flow Feb. 27th 2014 Yan 1 #12;Studied ProblemsD 2120 297 629,640 2 #12;Results 3JetDiameter Case · VOF 3 Initialization (t = 0 s) Z Z #12;Results 3JetDiameter Case (click to watch the movie) 4 · VOF 0 Jet

  13. Formation of Jets by Baroclinic Turbulence BRIAN F. FARRELL

    E-Print Network [OSTI]

    Farrell, Brian F.

    Formation of Jets by Baroclinic Turbulence BRIAN F. FARRELL Department of Earth and Planetary spatial-scale jets; geophysical examples of this phenomenon include the Jovian banded winds and the earth's polar-front jet. These relatively steady large-scale jets arise from and are maintained by the smaller

  14. Turbulence transition and internal wave generation in density stratified jets

    E-Print Network [OSTI]

    Sutherland, Bruce

    Turbulence transition and internal wave generation in density stratified jets B. FL Sutherland (Received 3 June 1993; accepted 18 November 1993) The nonlinear evolution of an unstable symmetric jet torques. In this case, the mean flow of the fully evolved jet is stable to subharmonic disturbances

  15. Modeling of Noise Reduction for Turbulent Jets with Induced Asymmetry

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    (flight) conditions I. Introduction The exhaust of jet engines continues to be a significant contributorModeling of Noise Reduction for Turbulent Jets with Induced Asymmetry Dimitri Papamoschou and Sara for the noise reduction of dual-stream jets with induced asymmetry in the plume flow field, with emphasis

  16. Simulations of High Speed Turbulent Jets in Crossflows Xiaochuan Chai

    E-Print Network [OSTI]

    Mahesh, Krishnan

    of the turbulent mixing mechanisms are important in combustor design. Supersonic jets are used for attitude or roll crossflows of two different Mach numbers and showed the presence of large-scale stuctures. Kawai and Lele7

  17. Simulations of High Speed Turbulent Jets in Crossflow Xiaochuan Chai

    E-Print Network [OSTI]

    Mahesh, Krishnan

    understanding of the turbulent mixing mechanisms play important roles in combustor design. Supersonic jets used crossflows of two different Mach numbers and showed the presence of large-scale stuctures. Kawai and Lele7

  18. Micro-jets in confined turbulent cross flow

    SciTech Connect (OSTI)

    Kelman, J.B.; Greenhalgh, D.A. [School of Engineering, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Whiteman, M. [Rolls-Royce plc, Combustion systems, Moor Lane, Derby DE24 8BJ (United Kingdom)

    2006-03-01

    The mixing of sub-millimetre diameter jets issuing into a turbulent cross flow is examined with a combination of laser diagnostic techniques. The cross flow stream is in a confined duct and the micro-jet issue from the sides of injector vanes. A range of cross jet momentum ratios, cross flow temperatures and turbulence intensities are investigated to examine the influence on the jet mixing. Methane, seeded with acetone, was used to measure the concentrations of the jets and the mixing of the jet fluid in the duct. Unlike previous jet in cross flow work, mixing appears to be dominated by the free stream turbulence, rather than the cross jet momentum ratios. Temperature increases in the free stream appear to increase the rate of mixing in the duct, despite the associated decrease in the Reynolds number. The dominance of the free stream turbulence in controlling the mixing is of particular interest in respect of gas turbine injection systems, as the cross jet momentum ratio is insufficient in defining the mixing process. (author)

  19. Reduced-Order Modelling of Turbulent Jets for Noise Control

    E-Print Network [OSTI]

    École Normale Supérieure

    Reduced-Order Modelling of Turbulent Jets for Noise Control Michael Schlegel, Bernd R. Noack, an opportunity for model-based jet noise reduction is opening up by the rapidly evolving field of reduced and Gilead Tadmor Abstract A reduced-order modelling (ROM) strategy is pursued to achieve a mech- anistic

  20. Characterization of turbulent jet mixing in cylindrical tanks 

    E-Print Network [OSTI]

    Schulte, Casey M

    1998-01-01

    This objective of this thesis is to investigate the aphics. mixing offered by turbulent jets. This study focuses on the specific application of low viscosity jets (1-30 cP) introduced for the purpose of mixing non-stratifying, miscible fluids...

  1. The power of jets: New clues from radio circular polarization and X-rays

    E-Print Network [OSTI]

    Falcke, Heino

    The power of jets: New clues from radio circular polarization and X-rays Heino Falcke 1 , Thomas. Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor be explained by a signi#12;cant syn- chrotron contribution from jets also to their IR-to-X-ray spectrum

  2. Mixing at the external boundary of a submerged turbulent jet

    E-Print Network [OSTI]

    A. Eidelman; T. Elperin; N. Kleeorin; G. Hazak; I. Rogachevskii; O. Sadot; I. Sapir-Katiraie

    2009-05-11

    We study experimentally and theoretically mixing at the external boundary of a submerged turbulent jet. In the experimental study we use Particle Image Velocimetry and an Image Processing Technique based on the analysis of the intensity of the Mie scattering to determine the spatial distribution of tracer particles. An air jet is seeded with the incense smoke particles which are characterized by large Schmidt number and small Stokes number. We determine the spatial distributions of the jet fluid characterized by a high concentration of the particles and of the ambient fluid characterized by a low concentration of the tracer particles. In the data analysis we use two approaches, whereby one approach is based on the measured phase function for the study of the mixed state of two fluids. The other approach is based on the analysis of the two-point second-order correlation function of the particle number density fluctuations generated by tangling of the gradient of the mean particle number density by the turbulent velocity field. This gradient is formed at the external boundary of a submerged turbulent jet. We demonstrate that PDF of the phase function of a jet fluid penetrating into an external flow and the two-point second-order correlation function of the particle number density do not have universal scaling and cannot be described by a power-law function. The theoretical predictions made in this study are in a qualitative agreement with the obtained experimental results.

  3. Oscillations of a Turbulent Jet Incident Upon an Edge

    SciTech Connect (OSTI)

    J.C. Lin; D. Rockwell

    2000-09-19

    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.

  4. Modeling of NOx formation in circular laminar jet flames 

    E-Print Network [OSTI]

    Siwatch, Vivek

    2007-04-25

    of air entrainment by jet depends upon the Sc number of fuel. The higher the Sc number, the higher is the air entrained which lowers the flame temperature and hence NOx formation. With increasing Sc number, flame volume increases which leads...

  5. Second-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillat and E. Kaminski

    E-Print Network [OSTI]

    Kaminski, Edouard

    Second-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillat and E.1063/1.4767535 Investigations on the local entrainment velocity in a turbulent jet Phys. Fluids 24, 105110 (2012); 10-order model of entrainment in planar turbulent jets at low Reynolds number S. Paillata) and E. Kaminski

  6. LES of an Inclined Jet into a Supersonic Turbulent Crossflow

    E-Print Network [OSTI]

    Ferrante, Antonino; Dimotakis, Paul E; Stephens, Mike; Adams, Paul; Walters, Richard

    2009-01-01

    This short article describes flow parameters, numerical method, and animations of the fluid dynamics video "LES of an Inclined Jet into a Supersonic Turbulent Crossflow" (http://ecommons.library.cornell.edu/bitstream/1813/14073/3/GFM-2009.mpg [high-resolution] and http://ecommons.library.cornell.edu/bitstream/1813/14073/2/GFM-2009-web.m1v [low-resolution] video). We performed large-eddy simulation with the sub-grid scale (LES-SGS) stretched-vortex model of momentum and scalar transport to study the gas-dynamics interactions of a helium inclined round jet into a supersonic ($M=3.6$) turbulent (\\Reth$ =13\\times10^3$) air flow over a flat surface. The video shows the temporal development of Mach-number and magnitude of density-gradient in the mid-span plane, and isosurface of helium mass-fraction and $\\lam_2$ (vortical structures). The identified vortical structures are sheets, tilted tubes, and discontinuous rings. The vortical structures are shown to be well correlated in space and time with helium mass-fracti...

  7. One-dimensional turbulence model simulations of autoignition of hydrogen/carbon monoxide fuel mixtures in a turbulent jet

    SciTech Connect (OSTI)

    Gupta, Kamlesh G.; Echekki, Tarek [Department of Mechanical and Aerospace Engineering, North Carolina State University, NC (United States)

    2011-02-15

    The autoignition of hydrogen/carbon monoxide in a turbulent jet with preheated co-flow air is studied using the one-dimensional turbulence (ODT) model. The simulations are performed at atmospheric pressure based on varying the jet Reynolds number and the oxidizer preheat temperature for two compositions corresponding to varying the ratios of H{sub 2} and CO in the fuel stream. Moreover, simulations for homogeneous autoignition are implemented for similar mixture conditions for comparison with the turbulent jet results. The results identify the key effects of differential diffusion and turbulence on the onset and eventual progress of autoignition in the turbulent jets. The differential diffusion of hydrogen fuels results in a reduction of the ignition delay relative to similar conditions of homogeneous autoignition. Turbulence may play an important role in delaying ignition at high-turbulence conditions, a process countered by the differential diffusion of hydrogen relative to carbon monoxide; however, when ignition is established, turbulence enhances the overall rates of combustion of the non-premixed flame downstream of the ignition point. (author)

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

    E-Print Network [OSTI]

    Ray, Jaideep

    Bayesian calibration of a k - turbulence model for predictive jet-in-crossflow simulations Jaideep skill in jet-in-crossflow simulations. The method is based on the hypotheses that (1) informative features of jet-in-crossflow interactions and (2) one can construct surrogates of RANS models

  9. Parabolized stability equation models for predicting large-scale mixing noise of turbulent round jets

    E-Print Network [OSTI]

    Colonius, Tim

    jets D. Rodr´iguez1 , A. Samanta1 , A. V. G. Cavalieri2 , T. Colonius1§ and P. Jordan2¶ 1 Department-frequency, large-scale wavepacket structures and their radiated sound in high- speed turbulent round jets. Linear envelope and phase measured using a microphone array placed just outside the jet shear layer.1,2 Here we

  10. Emergence of Jets from Turbulence in the Shallow-Water Equations on an Equatorial Beta Plane

    E-Print Network [OSTI]

    Farrell, Brian F.

    Emergence of Jets from Turbulence in the Shallow-Water Equations on an Equatorial Beta Plane BRIAN (Manuscript received 2 September 2008, in final form 24 April 2009) ABSTRACT Coherent jets, such as the Jovian the essential mechanism of jet formation, which is systematic eddy mo- mentum flux directed up the mean velocity

  11. ANALYSIS OF TURBULENT MIXING JETS IN LARGE SCALE TANK

    SciTech Connect (OSTI)

    Lee, S; Richard Dimenna, R; Robert Leishear, R; David Stefanko, D

    2007-03-28

    Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for sludge mixing and removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations. A computational fluid dynamics approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled sludge. A qualitative comparison with sludge removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual sludge properties.

  12. Medium-induced jet evolution: wave turbulence and energy loss

    E-Print Network [OSTI]

    Leonard Fister; Edmond Iancu

    2014-09-06

    We study the gluon cascade generated via successive medium-induced branchings by an energetic parton propagating through a dense QCD medium. We focus on the high-energy regime where the energy $E$ of the leading particle is much larger than the characteristic medium scale $\\omega_c=\\hat q L^2/2$, with $\\hat q$ the jet quenching parameter and $L$ the distance travelled through the medium. In this regime the leading particle loses only a small fraction $\\sim\\alpha_s(\\omega_c/E)$ of its energy and can be treated as a steady source of radiation for gluons with energies $\\omega\\le\\omega_c$. For this effective problem with a source, we obtain exact analytic solutions for the gluon spectrum and the energy flux. The solutions exhibit wave turbulence: the basic physical process is a continuing fragmentation which is `quasi-democratic' (i.e. quasi-local in energy) and which provides an energy transfer from the source to the medium at a rate (the energy flux $\\mathcal{F}$) which is quasi-independent of $\\omega$. The locality of the branching process implies a spectrum of the Kolmogorov-Obukhov type, i.e. a power-law spectrum which is a fixed point of the branching process and whose strength is proportional to the energy flux: $D(\\omega)\\sim\\mathcal{F}/\\sqrt\\omega$ for $\\omega\\ll\\omega_c$. Via this turbulent flow, the gluon cascade loses towards the medium an energy $\\Delta E\\sim\\alpha_s^2\\omega_c$, which is independent of the initial energy $E$ of the leading particle and of the details of the thermalization mechanism at the low-energy end of the cascade. This energy is carried away by very soft gluons, which propagate at very large angles with respect to the jet axis. Our predictions for the value of $\\Delta E$ and for its angular distribution appear to agree quite well, qualitatively and even semi-quantitatively, with the phenomenology of di-jet asymmetry in nucleus-nucleus collisions at the LHC.

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

    E-Print Network [OSTI]

    Church, Jeffrey H. (Jeffrey Harrison)

    2012-01-01

    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 ...

  14. 43rd AIAA Aerospace Sciences Meeting and Exhibit, Jan 1013, Reno, Nevada Direct numerical simulation of turbulent jets in crossflow

    E-Print Network [OSTI]

    Mahesh, Krishnan

    simulation of turbulent jets in crossflow Suman Muppidi and Krishnan Mahesh University of Minnesota, Minneapolis, MN, 55455, USA Direct numerical simulations are used to study a round turbulent jet in a laminar crossflow. The velocity ratio of the jet to that of the crossflow is 5.7 and the Reynolds number based

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

    SciTech Connect (OSTI)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard

    2014-08-15

    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.

  16. VELOCITY FIELD OF A ROUND TURBULENT TRANSVERSE JET Suman Muppidi

    E-Print Network [OSTI]

    Mahesh, Krishnan

    - bulent jet in a laminar crossflow. The velocity ratio is 5.7 and the Reynolds number is 5000. Mean Jets in crossflow, also called `transverse jets' are defined as the flow field where a jet of fluid enters and interacts with a crossflowing fluid. Examples of jets in crossflow are fuel injectors

  17. Impingement heat transfer within arrays of circular jets including the effect of crossflow

    SciTech Connect (OSTI)

    Matsumoto, Ryosuke; Ishihara, Isao; Yabe, Toshiaki; Ikeda, Keita; Kikkawa, Shinzo; Senda, Mamoru

    1999-07-01

    The purpose of this work is to investigate the heat transfer and the flow characteristics for the arrays of impingement jets taking into consideration the effect of the crossflow. In this experiment, two types of the crossflow schemes, referred to as the minimum crossflow and the maximum crossflow by the Obot et al. (1987), were examined. In the case of the maximum crossflow, the exhaust air was restricted by the side wall to leave through one side of the jet array. In the case of the minimum crossflow, the side wall was removed, and the exhaust air flowed away through all four edges of the jet array. To examine the flow pattern of the exhaust air, the flow visualization by the smoke flow was carried out. The air after impinging to the target surface was entrained into the downstream adjacent jet. The exhaust air was discharged to the outside of array through two ways: One was that the air was discharged to outside by entraining into the downstream adjacent jet. The other was that the exhaust air was discharged along the endwall surface on the mid-span of adjacent jets. The thermosensitive liquid crystal sheet was applied to measure the temperature distributions and to obtain the local heat transfer coefficients on the impingement surface. The local Nusselt number distribution for the maximum crossflow was hardly decreased in the downstream rows, although the velocity of the exhaust air increased. In the downstream row, however, the distribution of the local Nusselt number is non-circular shape because of the exhaust air. The averaged Nusselt number for the maximum crossflow was slightly lower than that in the case of minimum crossflow.

  18. Random Vortex-Street Model for a Self-Similar Plane Turbulent Jet

    E-Print Network [OSTI]

    Victor L'vov; Anna Pomyalov; Itamar Procaccia; Rama Govindarajan

    2008-03-18

    We ask what determines the (small) angle of turbulent jets. To answer this question we first construct a deterministic vortex-street model representing the large scale structure in a self-similar plane turbulent jet. Without adjustable parameters the model reproduces the mean velocity profiles and the transverse positions of the large scale structures, including their mean sweeping velocities, in a quantitative agreement with experiments. Nevertheless the exact self similar arrangement of the vortices (or any other deterministic model) necessarily leads to a collapse of the jet angle. The observed (small) angle results from a competition between vortex sweeping tending to strongly collapse the jet and randomness in the vortex structure, with the latter resulting in a weak spreading of the jet.

  19. Quantitative Imaging of Multi-component Turbulent Jets

    E-Print Network [OSTI]

    Victoria, University of

    to emulate releases in which leak geometry is circular. Effects of buoyancy, crossflow and adjacent surfaces................................................................................................3 1.2.2 Crossflow

  20. Experimental observations on transition to turbulence in confined coaxial jets and other boundary layer flows

    SciTech Connect (OSTI)

    Gore, R.A. (Los Alamos National Lab., NM (USA)); Crowe, C.T. (Washington State Univ., Pullman, WA (USA). Dept. of Mechanical and Materials Engineering); Bejan, A. (Duke Univ., Durham, NC (USA). Dept. of Mechanical Engineering and Materials Science)

    1990-01-01

    Experiments performed demonstrate the transition to turbulent flow of water jets discharging coaxially into a stream confined in a round duct. The critical Reynolds number is shown to be a strong function of velocity ratio. From the flow visualization it is shown that a proportionality between the laminar length of the jet (L) and the wavelength ({lambda}) can be seen in the region of transition to turbulence. The proportionality coincides with similar observations concerning the transition to turbulence in various other flows. A brief argument based on scale analysis is presented for the confined coaxial jet and round plume. The apparent universality of the L/{lambda} {approximately} O(10) scaling law supports the conclusion that the laminar sections of all naturally progressing boundary layer-type flows are geometrically similar. 21 refs., 8 figs.

  1. Abstract--The sound generated during the production of the sibilant [s] results from the impact of a turbulent jet on the

    E-Print Network [OSTI]

    Van Hirtum, Annemie

    of a turbulent jet on the incisors. Physical modeling of this phenomenon depends on the characterization by the development of a jet of air in the oral tract. The interaction of this jet with different components at the origin of the different fricative sounds. The sibilant [s] results from the impact of a turbulent jet

  2. The subject flow was created by the discharge of jet fluid, from a circular orifice (diameter D), into a cross--flow. The former is

    E-Print Network [OSTI]

    Feeny, Brian

    was restricted to the region near the jet exit and it involved jet--to--free stream velocity ratios (R v~/u0ABSTRACT The subject flow was created by the discharge of jet fluid, from a circular orifice by the free stream velocity, U, extant above the thin boundary layer (o

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

    E-Print Network [OSTI]

    Riley, Benjamin Matthew

    2009-05-15

    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...

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

    E-Print Network [OSTI]

    Colonius, Tim

    instability wave at any given frequency as representative of the energy carrying wave componentAn evaluation of linear instability waves as sources of sound in a supersonic turbulent jet Kamran Mohsenia) Division of Engineering and Applied Science, California Institute of Technology, Pasadena

  5. Multi-Spacecraft Measurement of Turbulence within a Magnetic Reconnection Jet

    E-Print Network [OSTI]

    Osman, K T; Matthaeus, W H; Hnat, B; Chapman, S C; Khotyaintsev, Yu V

    2015-01-01

    The relationship between magnetic reconnection and plasma turbulence is investigated using multipoint in-situ measurements from the Cluster spacecraft within a high-speed reconnection jet in the terrestrial magnetotail. We show explicitly that work done by electromagnetic fields on the particles, $\\mathbf{J}\\cdot\\mathbf{E}$, has a non-Gaussian distribution and is concentrated in regions of high electric current density. Hence, magnetic energy is converted to kinetic energy in an intermittent manner. Furthermore, we find the higher-order statistics of magnetic field fluctuations generated by reconnection are characterized by multifractal scaling on magnetofluid scales and non-Gaussian global scale invariance on kinetic scales. These observations suggest $\\mathbf{J}\\cdot\\mathbf{E}$ within the reconnection jet has an analogue in fluid-like turbulence theory in that it proceeds via coherent structures generated by an intermittent cascade. This supports the hypothesis that turbulent dissipation is highly nonunifor...

  6. Composition PDF/photon Monte Carlo modeling of moderately sooting turbulent jet flames

    SciTech Connect (OSTI)

    Mehta, R.S.; Haworth, D.C.; Modest, M.F. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-15

    A comprehensive model for luminous turbulent flames is presented. The model features detailed chemistry, radiation and soot models and state-of-the-art closures for turbulence-chemistry interactions and turbulence-radiation interactions. A transported probability density function (PDF) method is used to capture the effects of turbulent fluctuations in composition and temperature. The PDF method is extended to include soot formation. Spectral gas and soot radiation is modeled using a (particle-based) photon Monte Carlo method coupled with the PDF method, thereby capturing both emission and absorption turbulence-radiation interactions. An important element of this work is that the gas-phase chemistry and soot models that have been thoroughly validated across a wide range of laminar flames are used in turbulent flame simulations without modification. Six turbulent jet flames are simulated with Reynolds numbers varying from 6700 to 15,000, two fuel types (pure ethylene, 90% methane-10% ethylene blend) and different oxygen concentrations in the oxidizer stream (from 21% O{sub 2} to 55% O{sub 2}). All simulations are carried out with a single set of physical and numerical parameters (model constants). Uniformly good agreement between measured and computed mean temperatures, mean soot volume fractions and (where available) radiative fluxes is found across all flames. This demonstrates that with the combination of a systematic approach and state-of-the-art physical models and numerical algorithms, it is possible to simulate a broad range of luminous turbulent flames with a single model. (author)

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

    E-Print Network [OSTI]

    Ho, Chu Eu

    2005-01-01

    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 ...

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

    E-Print Network [OSTI]

    Helluy, Philippe

    Turbulence Mixture Fraction Spray mass coupling evaporation rate moment coupling mixing heat exchange Spray 2 Bernd Binninger1 Norbert Peters1 1 Institute for Combustion Technology RWTH-Aachen 2 Mechanical composition pollutant formation Combustion stability Need to accurately model Spray Process From injection

  9. Structure of turbulent hydrogen jet diffusion flames with or without swirl

    SciTech Connect (OSTI)

    Takahashi, Fumiaki; Vangsness, M.D.; Durbin, M.D.; Schmoll, W.J.

    1995-12-31

    The aerodynamic and thermal structure of double-concentric turbulent hydrogen jet diffusion flames with or without swirl has been investigated using three-component laser-Doppler velocimetry (LDV) and coherent anti-Stokes Raman spectroscopy. The LDV data were conditionally sampled upon the origin of the fluid (jet, annulus, or external) to avoid the velocity-bias problem and to gain more detailed information on the turbulent structure. As the mean jet velocity was increased, the turbulent flame zone shifted inward and the thermal layer became thinner, whereas swirl created a radial velocity even at the annulus air exit, thereby shifting the flame zone outward and broadening the thermal layer. The probability-density functions (pdf) of velocity components,m their 21 moments (up to fourth order), temperature pdf, mean, and root-mean-square fluctuation temperature were determined at numerous radial locations at seven axial heights in the near field (<26.5 jet diameters). The data can be used to validate computational models.

  10. TiO{sub 2} Film Deposition by Atmospheric Thermal Plasma CVD Using Laminar and Turbulence Plasma Jets

    SciTech Connect (OSTI)

    Ando, Yasutaka; Tobe, Shogo [Ashikaga Institute of Technology, 268-1 Omae, Ashikaga, Tochigi 326-8558 (Japan); Tahara, Hirokazu [Osaka Institute of Technology, 5-16-1 Omiya, Asahi-Ku, Osaka 535-8585 (Japan)

    2008-02-21

    In this study, to provide continuous plasma atmosphere on the substrate surface in the case of atmospheric thermal plasma CVD, TiO{sub 2} film deposition by thermal plasma CVD using laminar plasma jet was carried out. For comparison, the film deposition using turbulence plasma jet was conducted as well. Consequently, transition of the plasma jet from laminar to turbulent occurred on the condition of over 3.5 1/min in Ar working gas flow rate and the plasma jet became turbulent on the condition of over 10 1/min. In the case of the turbulent plasma jet use, anatase rich titanium oxide film could be obtained though plasma jet could not contact with the surface of the substrate continuously even on the condition that feedstock material was injected into the plasma jet. On the other hand,, in the case of laminar gas flow rate, the plasma jet could contact with the substrate continuously without melt down of the substrate during film deposition. Besides, titanium oxide film could be obtained even in the case of the laminar plasma jet use. From these results, this technique was thought to have high potential for atmospheric thermal plasma CVD.

  11. Investigation of Flame Stretch in Turbulent Lifted Jet Flame

    E-Print Network [OSTI]

    Ruan, S.; Swaminathan, N.; Mizobuchi, Y.

    2014-02-24

    jet flame, Mixed mode combustion, 2 1 Introduction The occurrence of mixed mode combustion in many practical devices such as strati- fied charge direct injection engines and lean burn gas turbine combustor is common. In these devices, typically fuel... ., 2009; Richardson et al., 2010; Chakraborty et al., 2010) and experimental (Hartung et al., 2008; Steinberg et al., 2012) studies of premixed combustion and stratified combustion (Malkeson and Chakraborty, 2011) have demonstrated that the reactive scalar...

  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. Fluids 24, 086101 (2012) The influence of large-scale structures on entrainment in a decelerating://pof.aip.org/about/rights_and_permissions #12;PHYSICS OF FLUIDS 24, 055108 (2012) Large-scale eddies and their role in entrainment in turbulent

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

    SciTech Connect (OSTI)

    Wang, Hai; Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01

    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.

  14. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

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

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  15. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane air jet flames

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

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  16. Heat transfer characteristics of circular impinging jet arrays in an annular section with cross flow effects 

    E-Print Network [OSTI]

    Mhetras, Shantanu Prakash

    2002-01-01

    Jet impingement has been shown to be an effective method for enhancing convective heat transfer. There are a variety of applications of impinging jets in industry, including tempering and shaping of glass, annealing of metal and plastic sheets...

  17. Relation Between Type-II ELMs, Edge Localized Turbulence, Washboard Modes and Energy Losses Between ELMs in High Density ELMy H-modes on JET

    E-Print Network [OSTI]

    Relation Between Type-II ELMs, Edge Localized Turbulence, Washboard Modes and Energy Losses Between ELMs in High Density ELMy H-modes on JET

  18. Diffusive radiation in Langmuir turbulence produced by jet shocks

    E-Print Network [OSTI]

    Gregory D. Fleishman; Igor N. Toptygin

    2007-06-03

    Anisotropic distributions of charged particles including two-stream distributions give rise to generation of either stochastic electric fields (in the form of Langmuir waves, Buneman instability) or random quasi-static magnetic fields (Weibel and filamentation instabilities) or both. These two-stream instabilities are known to play a key role in collisionless shock formation, shock-shock interactions, and shock-induced electromagnetic emission. This paper applies the general non-perturbative stochastic theory of radiation to study electromagnetic emission produced by relativistic particles, which random walk in the stochastic electric fields of the Langmuir waves. This analysis takes into account the cumulative effect of uncorrelated Langmuir waves on the radiating particle trajectory giving rise to angular diffusion of the particle, which eventually modifies the corresponding radiation spectra. We demonstrate that the radiative process considered is probably relevant for emission produced in various kinds of astrophysical jets, in particular, prompt gamma-ray burst spectra, including X-ray excesses and prompt optical flashes.

  19. Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames

    SciTech Connect (OSTI)

    Weiland, N.T.; Strakey, P.A.

    2007-03-01

    Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program’s aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.

  20. Triple cascade behaviour in QG and drift turbulence and generation of zonal jets

    E-Print Network [OSTI]

    Sergey Nazarenko; Brenda Quinn

    2009-05-08

    We study quasi-geostrophic turbulence and plasma drift turbulence within the Charney-Hasegawa-Mima (CHM) model. We focus, theoretically and using numerical simulations, on conservation of {\\em zonostrophy} and on its role in the formation of the zonal jets. The zonostrophy invariant was first predicted in \\cite{perm,BNZ_invariant} in two special cases -- large-scale turbulence and anisotropic turbulence. Papers \\cite{perm,BNZ_invariant} also predicted that the three invariants, energy, enstrophy and zonostrophy, will cascade anisotropically into non-intersecting sectors in the $k$-space, so that the energy cascade is "pushed" into the large-scale zonal scales. In the present paper, we consider the scales much less than the Rossby deformation radius and generalise the Fj{\\o}rtoft argument of \\cite{perm,BNZ_invariant} to find the directions of the three cascades in this case. For the first time, we demonstrate numerically that zonostrophy is well conserved by the CHM model, and that the energy, enstrophy and zonostrophy cascade as prescribed by the Fj{\\o}rtoft argument if the nonlinearity is sufficiently weak. Moreover, numerically we observe that zonostrophy is conserved surprisingly well at late times and the triple-cascade picture is rather accurate even if the initial nonlinearity is strong.

  1. The application of complex network time series analysis in turbulent heated jets

    SciTech Connect (OSTI)

    Charakopoulos, A. K.; Karakasidis, T. E. Liakopoulos, A.; Papanicolaou, P. N.

    2014-06-15

    In the present study, we applied the methodology of the complex network-based time series analysis to experimental temperature time series from a vertical turbulent heated jet. More specifically, we approach the hydrodynamic problem of discriminating time series corresponding to various regions relative to the jet axis, i.e., time series corresponding to regions that are close to the jet axis from time series originating at regions with a different dynamical regime based on the constructed network properties. Applying the transformation phase space method (k nearest neighbors) and also the visibility algorithm, we transformed time series into networks and evaluated the topological properties of the networks such as degree distribution, average path length, diameter, modularity, and clustering coefficient. The results show that the complex network approach allows distinguishing, identifying, and exploring in detail various dynamical regions of the jet flow, and associate it to the corresponding physical behavior. In addition, in order to reject the hypothesis that the studied networks originate from a stochastic process, we generated random network and we compared their statistical properties with that originating from the experimental data. As far as the efficiency of the two methods for network construction is concerned, we conclude that both methodologies lead to network properties that present almost the same qualitative behavior and allow us to reveal the underlying system dynamics.

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

    E-Print Network [OSTI]

    Pouransari, Z; Johansson, A V

    2015-01-01

    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

    2015-02-21

    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. HPC realization of a controlled turbulent round jet using OpenFOAM

    E-Print Network [OSTI]

    Önder, Asim

    2014-01-01

    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...

  5. 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.

    1993-12-01

    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.

  6. An Analysis of Self-similarity, Momentum Conservation and Energy Transport for an Axisymmetric Turbulent Jet through a Staggered Array of Rigid Emergent Vegetation 

    E-Print Network [OSTI]

    Allen, Jon Scott

    2013-05-29

    as storm protection using an ADV measurement technique, and is the first to apply jet self-similarity analysis to characterize the overall mean and turbulent flow properties of a three-dimensional axisymmetric jet through a vegetated array. The mean axial...

  7. Simultaneous imaging of OH, formaldehyde, and temperature of turbulent nonpremixed jet flames in a heated and diluted coflow

    SciTech Connect (OSTI)

    Medwell, Paul R.; Kalt, Peter A.M.; Dally, Bassam B. [School of Mechanical Engineering, The University of Adelaide, S.A. 5005 (Australia)

    2007-01-15

    This paper reports measurements in turbulent nonpremixed CH{sub 4}/H{sub 2} jet flames issuing into a heated and highly diluted coflow. These conditions emulate those of moderate or intense low-oxygen-dilution (MILD) combustion. The spatial distribution of the hydroxyl radical (OH), formaldehyde (H{sub 2}CO), and temperature, imaged using planar laser-induced fluorescence and Rayleigh scattering laser diagnostic techniques, are measured and presented. Comparisons are made between three jet Reynolds numbers and two coflow O{sub 2} levels. Measurements are taken at two downstream locations. The burner used in this work facilitates the additional study on the effects of the entrainment of surrounding air on the flame structure at downstream locations. Reducing the coflow oxygen level is shown to lead to a suppression of OH as a result of the reduced temperatures in the reaction zone. Decreasing the oxygen level of the coflow also results in a broadening of the OH distribution. At downstream locations, the surrounding air mixes with the jet and coflow. The subsequent drop in the temperature of the oxidant stream can lead to a rupture of the OH layer. Localized extinction allows premixing of the fuel with the surrounding air. The result is an increase in the reaction rate, highlighting the need for homogeneous mixing to maintain MILD combustion conditions. (author)

  8. Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

    E-Print Network [OSTI]

    Heinz, Stefan

    simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart, n i 2 N0; 1 = kinematic viscosity T = Reynolds-averaged Navier­Stokes turbulent viscosity

  9. Convective heat transfer in the laminar-turbulent transition region with molten salt in a circular tube

    SciTech Connect (OSTI)

    Yu-ting, Wu; Bin, Liu; Chong-fang, Ma; Hang, Guo [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)

    2009-10-15

    In order to understand the heat transfer characteristics of molten salt and testify the validity of the well-known empirical convective heat transfer correlations, experimental study on transition convective heat transfer with molten salt in a circular tube was conducted. Molten salt circulations were realized and operated in a specially designed system over 1000 h. The average forced convective heat transfer coefficients of molten salt were determined by least-squares method based on the measured data of flow rates and temperatures. Finally, a heat transfer correlation of transition flow with molten salt in a circular tube was obtained and good agreement was observed between the experimental data of molten salt and the well-known correlations presented by Hausen and Gnielinski, respectively. (author)

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

    E-Print Network [OSTI]

    Roman, Jennifer Claire

    1996-01-01

    Passive tracer dispersion is studied in a two-layer, quasigeostrophic, betaplane model in which persistent, steady, zonal jets are observed. Particle trajectories and statistics are examined for barriers to or mechanisms for mixing. Simulations...

  11. Three dimensional analysis of turbulent steam jets in enclosed structures : a CFD approach.

    SciTech Connect (OSTI)

    Ishii, M.; NguyenLe, Q.

    1999-04-20

    This paper compares the three-dimensional numerical simulation with the experimental data of a steam blowdown event in a light water reactor containment building. The temperature and pressure data of a steam blowdown event was measured at the Purdue University Multi-Dimensional Integrated Test Assembly (PUMA), a scaled model of the General Electric simplified Boiling Water Reactor. A three step approach was used to analyze the steam jet behavior. First, a 1-Dimensional, system level RELAP5/Mod3.2 model of the steam blowdown event was created and the results used to set the initial conditions for the PUMA blowdown experiments. Second, 2-Dimensional CFD models of the discharged steam jets were computed using PHOENICS, a commercially available CFD package. Finally, 3-Dimensional model of the PUMA drywell was created with the boundary conditions based on experimental measurements. The results of the 1-D and 2-D models were reported in the previous meeting. This paper discusses in detail the formulation and the results of the 3-Dimensional PHOENICS model of the PUMA drywell. It is found that the 3-D CFD solutions compared extremely well with the measured data.

  12. Numerical Simulations of Boiling Jet Impingement Cooling in Power Electronics

    SciTech Connect (OSTI)

    Narumanchi, S.; Troshko, A.; Hassani, V.; Bharathan, D.

    2006-12-01

    This paper explores turbulent boiling jet impingement for cooling power electronic components in hybrid electric vehicles.

  13. 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

    1995-01-01

    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...

  14. Turbulence and combustion interaction: High resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH, OH, and CH{sub 2}O in a piloted premixed jet flame

    SciTech Connect (OSTI)

    Li, Z.S.; Li, B.; Sun, Z.W.; Alden, M. [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bai, X.S. [Division of Fluid Mechanics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)

    2010-06-15

    High resolution planar laser-induced fluorescence (PLIF) was applied to investigate the local flame front structures of turbulent premixed methane/air jet flames in order to reveal details about turbulence and flame interaction. The targeted turbulent flames were generated on a specially designed coaxial jet burner, in which low speed stoichiometric gas mixture was fed through the outer large tube to provide a laminar pilot flame for stabilization of the high speed jet flame issued through the small inner tube. By varying the inner tube flow speed and keeping the mixture composition as that of the outer tube, different flames were obtained covering both the laminar and turbulent flame regimes with different turbulent intensities. Simultaneous CH/CH{sub 2}O, and also OH PLIF images were recorded to characterize the influence of turbulence eddies on the reaction zone structure, with a spatial resolution of about 40 {mu}m and temporal resolution of around 10 ns. Under all experimental conditions, the CH radicals were found to exist only in a thin layer; the CH{sub 2}O were found in the inner flame whereas the OH radicals were seen in the outer flame with the thin CH layer separating the OH and CH{sub 2}O layers. The outer OH layer is thick and it corresponds to the oxidation zone and post-flame zone; the CH{sub 2}O layer is thin in laminar flows; it becomes broad at high speed turbulent flow conditions. This phenomenon was analyzed using chemical kinetic calculations and eddy/flame interaction theory. It appears that under high turbulence intensity conditions, the small eddies in the preheat zone can transport species such as CH{sub 2}O from the reaction zones to the preheat zone. The CH{sub 2}O species are not consumed in the preheat zone due to the absence of H, O, and OH radicals by which CH{sub 2}O is to be oxidized. The CH radicals cannot exist in the preheat zone due to the rapid reactions of this species with O{sub 2} and CO{sub 2} in the inner-layer of the reaction zones. The local PLIF intensities were evaluated using an area integrated PLIF signal. Substantial increase of the CH{sub 2}O signal and decrease of CH signal was observed as the jet velocity increases. These observations raise new challenges to the current flamelet type models. (author)

  15. Fig.1 Instantaneous Flow and Temperature Fields for an Impinging Circular Jet Transient Flow and Temperature Transport in Continuous Casting of Steel Slabs

    E-Print Network [OSTI]

    Kihm, IconKenneth David

    of defects in steel casting, and in predicting heat transfer rates to the solidifying region. A classic is removed in the mold. The jets exiting the nozzle ports are shown to fluctuate, producing temperature Instantaneous Temperature Fields in the Mold region of a Continuous Caster of Steel #12;

  16. Numerical Simulations for Jet-Proton Interaction

    E-Print Network [OSTI]

    McDonald, Kirk

    inside the jet. Setup of the Simulation of the Circular Jet downstream upstream #12;3 Sergei's result at the Initial Time Energy deposition at x=0 plane, the pressure unit is bar upstream downstream #12;4 Results of the Simulation of the Elliptic Jet downstream upstream #12;7 Jet surface at 0 and 140 microsecond Results from

  17. Jet Streams Jet Streams

    E-Print Network [OSTI]

    Hennon, Christopher C.

    ATMS 310 Jet Streams Jet Streams A jet stream is an intense (30+ m/s in upper troposphere, 15+ m of air associated with strong (at least 5-10 ms-1 km-1 ) vertical wind shear. A Jet Streak is an isotach maximum embedded within a jet stream. Jet streams are mesoscale in the cross-flow direction and synoptic

  18. Jets with Reversing Buoyancy

    E-Print Network [OSTI]

    Pandya, R V R

    2015-01-01

    A jet of heavy fluid is injected upwards, at time $t=0$, into a lighter fluid and reaches a maximum height at time $t=t_i$ and then flows back around the upward flow. A similar flow situation occurs for a light fluid injected downward into a heavy one. In this paper an exact analytical expression for $t_i$ is derived. The expression remains valid for laminar and turbulent buoyant jets with or without swirl.

  19. Under consideration for publication in J. Fluid Mech. 1 Emergence and equilibration of jets in

    E-Print Network [OSTI]

    Farrell, Brian F.

    Under consideration for publication in J. Fluid Mech. 1 Emergence and equilibration of jets in beta scale jets that are not forced directly at the jet scale are a prominent feature of rotating turbulence. These jets arise and are supported by systematic orga- nization of the turbulent Reynolds stresses

  20. jet-compressible-gas-july25.tex 1 Liquid jet in a high Mach number air stream

    E-Print Network [OSTI]

    Joseph, Daniel D.

    jet-compressible-gas-july25.tex 1 Liquid jet in a high Mach number air stream T.Funada, D, Minneapolis, MN 55455, USA Abstract The instability of circular liquid jet immersed in a coflowing high growth rate for n = 1 modes exceeds n = 0 when the viscosity of the liquid jet is large. The effects

  1. On zonal jets in oceans Balasubramanya T. Nadiga1

    E-Print Network [OSTI]

    Nadiga, Balasubramanya T. "Balu"

    On zonal jets in oceans Balasubramanya T. Nadiga1 Received 26 January 2006; revised 29 March 2006 to the recently observed alternating zonal jets in oceans, the formation of these jets can be explained as due of alternating jets in Jovian atmospheres and two dimensional turbulence in zonally-periodic configurations

  2. AIAA Paper 2006-0102 Analysis of Jet Effects on Co-Flow Jet Airfoil

    E-Print Network [OSTI]

    Zha, Gecheng

    engine inlet j jet injection Freestream Greek Letters: Turbulent Dissipation Rate Ratio of SpecificAIAA Paper 2006-0102 Analysis of Jet Effects on Co-Flow Jet Airfoil Performance with Integrated Propulsion System Ge-Cheng Zha and Wei Gao Dept. of Mechanical and Aerospace Engineering University of Miami

  3. Center for Turbulence Research Annual Research Briefs 2008

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    in a supersonic turbulent crossflow By S. Kawai AND S. K. Lele 1. Motivation and objectives Important recent load, etc. Jet mixing in a supersonic crossflow (JISC) is a type of flow where compressible LES can, the enhancement of supersonic turbulent mixing of jet fuel and crossflow air is a critical issue in developing

  4. Modification of vortex dynamics and transport properties of transitional axisymmetric jets using zero-net-mass-flux actuation

    SciTech Connect (OSTI)

    Önder, Asim; Meyers, Johan

    2014-07-15

    We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub ?} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.

  5. 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

    2003-06-01

    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.

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

    E-Print Network [OSTI]

    Salpeter, Nathaniel O.

    2010-07-14

    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...

  7. The formation and evolution of synthetic jets Barton L. Smitha)

    E-Print Network [OSTI]

    Smith, Barton L.

    The formation and evolution of synthetic jets Barton L. Smitha) and Ari Glezer Woodruff School 1997; accepted 6 May 1998 A nominally plane turbulent jet is synthesized by the interactions of a train of a flexible diaphragm in a sealed cavity. Even though the jet is formed without net mass injection

  8. Axisymmetric Synthetic Jets: An Experimental and Theoretical Examination

    E-Print Network [OSTI]

    Mohseni, Kamran

    Axisymmetric Synthetic Jets: An Experimental and Theoretical Examination Gopi Krishnan and Kamran synthetic jet driven by a piezoelectric membrane issuing into a quiescent environment is studied in this paper. The self-similar behavior exhibited by both synthetic and continuous turbulent jets leads

  9. Federal Acquisition Regulation; Federal Acquisition Circular...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Regulation; Federal Acquisition Circular Federal Acquisition Regulation; Federal Acquisition Circular Federal Acquisition Regulation; Federal Acquisition Circular More Documents &...

  10. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, R.B.

    1994-08-16

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. 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. 11 figs.

  11. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, Robert B. (Wheatridge, CO)

    1994-01-01

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. 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.

  12. Primary Atomization of a Liquid Jet in Crossflow

    E-Print Network [OSTI]

    Rana, Sandeep

    2010-01-01

    In this fluid dynamics video, we present a visualization of the primary atomization of a turbulent liquid jet injected into a turbulent gaseous crossflow. It is based on a detailed numerical simulation of the primary atomization region of the jet using a finite volume, balanced force, incompressible LES/DNS flow solver coupled to a Refined Level Set Grid (RLSG) solver to track the phase interface position. The visualization highlights the two distinct breakup modes of the jet: the column breakup mode of the main liquid column and the ligament breakup mode on the sides of the jet and highlights the complex evolution of the phase interface geometry.

  13. Fuzzy Jets

    E-Print Network [OSTI]

    Mackey, Lester; Schwartzman, Ariel; Stansbury, Conrad

    2015-01-01

    Collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets. To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets, are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet tagging variables. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.

  14. Fuzzy Jets

    E-Print Network [OSTI]

    Lester Mackey; Benjamin Nachman; Ariel Schwartzman; Conrad Stansbury

    2015-09-07

    Collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets. To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets, are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet tagging variables. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.

  15. LABORATORY IV CIRCULAR MOTION

    E-Print Network [OSTI]

    Minnesota, University of

    Lab IV - 1 LABORATORY IV CIRCULAR MOTION The problems in this laboratory will help you investigate. OBJECTIVES: After successfully completing this laboratory, you should be able to: · Determine Laboratories I, II, and III. Before coming to the lab you should be able to: · Determine an object

  16. 44th AIAA Aerospace Sciences Meeting and Exhibit, Jan 912, Reno, Nevada Passive scalar mixing in jets in crossflow

    E-Print Network [OSTI]

    Mahesh, Krishnan

    in jets in crossflow Suman Muppidi and Krishnan Mahesh University of Minnesota, Minneapolis, MN, 55455 turbulent jet in a laminar crossflow. The velocity ratio of the jet to that of the crossflow is 5.7, the Schmidt number of the scalar is 1.49, and the jet­exit Reynolds number is 5000. The scalar field is used

  17. 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

  18. Jets in Soft-Collinear Effective Theory

    E-Print Network [OSTI]

    Hornig, Andrew

    2010-01-01

    Jet Functions . . . . . . . . . . . . . . . . . . . .Event Shapes . . . . . . . . . . . . . . . . . . . . . JetQuark Jet

  19. Federal Acquisition Regulation; Federal Acquisition Circular...

    Energy Savers [EERE]

    Federal Acquisition Regulation; Federal Acquisition Circular Federal Acquisition Regulation; Federal Acquisition Circular Federal Acquisition Regulation; Federal Acquisition...

  20. SMALL-APERTURE PHASED ARRAY STUDY OF NOISE FROM COAXIAL JETS

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    SMALL-APERTURE PHASED ARRAY STUDY OF NOISE FROM COAXIAL JETS Dimitri Papamoschou University of California, Irvine, California 92697-3975 The noise source distribution of coaxial jets at variable velocity by fine- scale turbulence (broadside direction). For zero velocity ratio (single-stream jet), the near

  1. Stellar jets

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2008-05-23

    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.

  2. Gravitomagnetic Jets

    E-Print Network [OSTI]

    C. Chicone; B. Mashhoon

    2011-03-12

    We present a family of dynamic rotating cylindrically symmetric Ricci-flat gravitational fields whose geodesic motions have the structure of gravitomagnetic jets. These correspond to helical motions of free test particles up and down parallel to the axis of cylindrical symmetry and are reminiscent of the motion of test charges in a magnetic field. The speed of a test particle in a gravitomagnetic jet asymptotically approaches the speed of light. Moreover, numerical evidence suggests that jets are attractors. The possible implications of our results for the role of gravitomagnetism in the formation of astrophysical jets are briefly discussed.

  3. Turbulent combustion

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

  4. Water jet rebounds on hydrophobic surfaces : a first step to jet micro-fluidics

    E-Print Network [OSTI]

    Franck Celestini; R. Kofman; Xavier Noblin; Mathieu Pellegrin

    2010-09-28

    When a water jet impinges upon a solid surface it produces a so called hydraulic jump that everyone can observe in the sink of its kitchen. It is characterized by a thin liquid sheet bounded by a circular rise of the surface due to capillary and gravitational forces. In this phenomenon, the impact induces a geometrical transition, from the cylindrical one of the jet to the bi-dimensional one of the film. A true jet rebound on a solid surface, for which the cylindrical geometry is preserved, has never been yet observed. Here we experimentally demonstrate that a water jet can impact a solid surface without being destabilized. Depending on the incident angle of the impinging jet, its velocity and the degree of hydrophobicity of the substrate, the jet can i) bounce on the surface with a fixed reflected angle, ii) land on it and give rise to a supported jet or iii) be destabilized, emitting drops. Capillary forces are predominant at the sub-millimetric jet scale considered in this work, along with the hydrophobic nature of the substrate. The results presented in this letter raise the fundamental problem of knowing why such capillary hydraulic jump gives rise to this unexpected jet rebound phenomenon. This study furthermore offers new and promising possibilities to handle little quantity of water through "jet micro-fluidics"

  5. Turbulence-chemistry interactions in reacting flows

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

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

    E-Print Network [OSTI]

    Gülder, Ömer 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

  7. Circular chemiresistors for microchemical sensors

    DOE Patents [OSTI]

    Ho, Clifford K. (Albuquerque, NM)

    2007-03-13

    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.

  8. Cosmic Jets

    E-Print Network [OSTI]

    C. Chicone; B. Mashhoon; K. Rosquist

    2011-02-17

    We discuss time-dependent gravitational fields that "accelerate" free test particles to the speed of light resulting in cosmic double-jet configurations. It turns out that complete gravitational collapse along a spatial axis together with corresponding expansion along the other two axes leads to the accelerated motion of free test particles up and down parallel to the collapse axis such that a double-jet pattern is asymptotically formed with respect to the collapsed configuration.

  9. Emerging Jets

    E-Print Network [OSTI]

    Pedro Schwaller; Daniel Stolarski; Andreas Weiler

    2015-05-11

    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.

  10. Jet observables without jet algorithms

    E-Print Network [OSTI]

    Bertolini, Daniele

    We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but ...

  11. Sandia Energy - Turbulent Combustion

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

    Combustion Home Transportation Energy Predictive Simulation of Engines Reacting Flow Experiments Turbulent Combustion Turbulent CombustionAshley Otero2015-10-30T01:39:47+00...

  12. Why Do Disks Form Jets?

    E-Print Network [OSTI]

    D Lynden-Bell

    2002-03-27

    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.

  13. Nuclear spin circular dichroism

    SciTech Connect (OSTI)

    Vaara, Juha; Rizzo, Antonio; Kauczor, Joanna; Norman, Patrick; Coriani, Sonia

    2014-04-07

    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.

  14. Dispersion in two-dimensional turbulent buoyant plumes

    E-Print Network [OSTI]

    Rocco, Stefano; Woods, Andrew W.

    2015-06-02

    terrestrial explosive volcanism. Journal of Geophysical Research 113 (B9), B09201. Chen, By Daoyi & Jirka, Gerhard H 1999 LIF study of plane jet bounded in shallow water layer. Journal of Hydraulic Engineering 125 (August), 817–826. Danckwerts, P. V. 1953... Continuous Flow Systems, Distribution of Residence Times. Chemical Engineering Science 2 (1). Daoyi, Chen & Jirka, Gerhard H. 1998 Linear stability analysis of turbulent mixing layers and jets in shallow water layers. Journal of Hydraulic Research 36 (5), 815...

  15. New perspectives on superparameterization for geophysical turbulence

    SciTech Connect (OSTI)

    Majda, Andrew J.; Grooms, Ian

    2014-08-15

    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.

  16. Heat transfer and flow of an impinged plate with an elliptic jet

    SciTech Connect (OSTI)

    Matsuda, Shoichi; Yaga, Minoru; Oyakawa, Kenyu

    1999-07-01

    The time and spatial temperature profiles on a jet impingement plate were measured using an infrared radiometer with a two-dimensional array of Indium-Antimony (In Sb) sensors for various nozzle exit-to-plate spaces for when the jet being issued from an elliptic nozzle impinges on the target plate. The isotherms of infrared images as well as heat transfer coefficients were obtained by measurement data. The heat transfer coefficients were also measured by using thermocouples. In order to compare the isotherms and heat transfer contours with flow patterns, the flows on the plate were visualized by the oil-film method, and the velocity and the turbulence intensity were measured by a hot wire anemometer. The phenomena of axes switching which are caused by the differences in self-induced velocity in non-circular vortices and have been the typical behaviors of free jets were observed on the impingement plate. The distribution of the isotherm and iso-heat transfer coefficients for the center portion were shorted in the major direction with an increase of the space between nozzle exit and impingement plate and elongated in the minor direction. The isotherms from the infrared image corresponded closely to the distribution of iso-heat transfer coefficients by using thermocouples. The shapes of flow patterns also corresponded to both the shape of the isotherms and the iso-heat transfer contours. In the twice length of nozzle diameter downstream from nozzle exit, the oil film pattern was elongated in the major axis direction for the center portion, which corresponded to both the lower temperature and higher heat transfer coefficient.

  17. Jet Quenching via Jet Collimation

    E-Print Network [OSTI]

    Jorge Casalderrey-Solana; Jose Guilherme Milhano; Urs Achim Wiedemann

    2010-12-03

    The ATLAS Collaboration recently reported strong modifications of dijet properties in heavy ion collisions. In this work, we discuss to what extent these first data constrain already the microscopic mechanism underlying jet quenching. Simple kinematic arguments lead us to identify a frequency collimation mechanism via which the medium efficiently trims away the soft components of the jet parton shower. Through this mechanism, the observed dijet asymmetry can be accomodated with values of $\\hat{q}\\, L$ that lie in the expected order of magnitude.

  18. Direct numerical simulation of turbulent reacting flows

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

  19. Haar LBP Gabor Jet boosting Gabor Jet

    E-Print Network [OSTI]

    Ai, Haizhou

    Boosting 1 boosting Haar LBP Gabor Jet boosting LBP Haar Gabor Jet boosting TP391. Further more, three kinds of local feature, Haar like feature, LBP histogram and Gabor jet are extracted, Haar like feature is more efficient for discriminating young and middle aged people, and Gabor Jet fits

  20. Circular Harmonic Decomposition Approach for Numerical Inversion of Circular Radon Transforms

    E-Print Network [OSTI]

    Louis, Alfred K.

    Circular Harmonic Decomposition Approach for Numerical Inversion of Circular Radon Transforms Gaël@num.uni-sb.de ABSTRACT Numerical inversions via circular harmonic decomposition for two classes of circular Radon transforms are established. The first class deals with the Radon transform (RT) de- fined on circular arcs

  1. CFD optimization study of high-efficiency jet ejectors 

    E-Print Network [OSTI]

    Watanawanavet, Somsak

    2009-05-15

    , separation, and energy consumption in the suction of the propelled stream. To maximize jet ejector performance, enhancing turbulent mixing should be a major consideration. The literatures indicate that the nozzle geometry should be well-designed to boost... design on jet ejector performance. In their experiment, two conically diverging nozzles were tested, but differing in the divergence angle. The exit and throat diameters of the nozzle were fixed in both cases. The experimental results show...

  2. Turbulent Flow Analysis and Coherent Structure Identification in Experimental Models with Complex Geometries 

    E-Print Network [OSTI]

    Amini, Noushin

    2012-02-14

    applying two different experimental methods. The first study involves the investigation of turbulent impinging jets through a staggered array of rods with or without crossflow. Such flows are crucial in various engineering disciplines. This experiment... ................................................................................................... 47 II.3.1. Time-Averaged Velocity Fields ................................................ 48 II.3.1.1. Single Impinging Jet in the Corner of Mid-Plane ...... 48 II.3.1.2. Single Impinging Jet in the Middle of the Measurement Plane...

  3. 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)

    1993-01-01

    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.

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

    DOE Patents [OSTI]

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

    1993-12-21

    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.

  5. Center for Turbulence Research Annual Research Briefs 2008

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    breakup of turbulent liquid jets in crossflow By M. G. Pai, O. Desjardins AND H. Pitsch 1. Motivation and objectives The problem of breakup of a liquid fuel in a crossflow finds relevance in applications in a crossflow is a result of a complex process that includes development of instabilities along the liquid

  6. DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A.

    2010-09-01

    By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

  7. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

  8. Experimental study of gas turbine blade film cooling and internal turbulated heat transfer at large Reynolds numbers 

    E-Print Network [OSTI]

    Mhetras, Shantanu

    2009-06-02

    superposition of effectiveness data from individual rows are comparable with that from full coverage film cooling. Internal heat transfer measurements are also performed in a high aspect ratio channel and from jet array impingement on a turbulated target wall...

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

    SciTech Connect (OSTI)

    Torii, Shuichi; Yano, Toshiaki; Tsuchino, Fumihiro

    1999-07-01

    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.

  10. 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.

  11. HEAVY QUARKS JETS

    E-Print Network [OSTI]

    Suzuki, M.

    2010-01-01

    i'iAsm Heavy Quark Jets iBirijets. Short-distance vs long-than a few wide angle sub-jets at to draw first skelton jet

  12. Turbulent flow in graphene

    E-Print Network [OSTI]

    Kumar S. Gupta; Siddhartha Sen

    2010-06-05

    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.

  13. Quantum Gravity and Turbulence

    E-Print Network [OSTI]

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

    2010-05-18

    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.

  14. Chaotic Jets

    E-Print Network [OSTI]

    Xavier Leoncini; George M. Zaslavsky

    2006-02-21

    The problem of characterizing the origin of the non-Gaussian properties of transport resulting from Hamiltonian dynamics is addressed. For this purpose the notion of chaotic jet is revisited and leads to the definition of a diagnostic able to capture some singular properties of the dynamics. This diagnostic is applied successfully to the problem of advection of passive tracers in a flow generated by point vortices. We present and discuss this diagnostic as a result of which clues on the origin of anomalous transport in these systems emerge.

  15. Gas-flow measurements in a jet flame using cross-correlation of high speed particle-images

    SciTech Connect (OSTI)

    Shioji, Masahiro; Kawasaki, Kiyoshi; Kawanabe, Hiroshi; Ikegami, Makoto

    1999-07-01

    Time changes of a two-dimensional distribution of velocities in a methane jet flame and a nitrogen jet are measured by cross-correlation particle image velocimetry (PIV). The mean velocity and the intensity of turbulence are obtained and compared with those measured by HWA in order to ascertain the accuracy of PIV. Furthermore, the effect of combustion on turbulence characteristics is discussed based on the deformation of eddies with time change and distribution of time and spatial scales.

  16. Eddy fluxes in baroclinic turbulence

    E-Print Network [OSTI]

    Thompson, Andrew F.

    2006-01-01

    to a single meandering jet stream in each hemisphere. Theremarks regions of intense jet streams that reach speeds ofwithin in the Earth’s jet stream. In this way, zonal jets in

  17. Interaction of Jets with the ISM of Radio Galaxies

    E-Print Network [OSTI]

    R. S. Sutherland; G. V. Bicknell

    2007-07-25

    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, including Radio and multi-band X-ray visualisations. These simulations are applicable to the GPS/CSS phase of some extragalactic radio sources. We identify four generic phases in the evolution of such a jet with the interstellar medium. The first is a `flood and channel'' phase, dominated by complex jet interactions with the dense cloudy medium close to the nucleus. A spherical, energy driven, bubble phase follows, where the bubble is larger than the disk scale, but the jet remains fully disrupted close to the nucleus. Then in a rapid, jet break--out phase, the jet breaks free of the last obstructing dense clouds, becomes collimated and pierces the more or less spherical bubble. In the final classical phase, the jet propagates in a momentum-dominated fashion similar to jets in single component hot haloes, leading to the classical jet -- cocoon -- bow-shock structure.

  18. Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    . Figure 1. Example of engine layout of Hybrid-Wing-Body airplane (Ref. 2). Research on jet-by-jetModeling of Jet-by-Jet Diffraction Dimitri Papamoschou The paper presents an analytical model for the prediction of jet-by-jet diffraction. The source jet is modeled as a radiating cylinder on which one can

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

    SciTech Connect (OSTI)

    Rutland, Christopher J.

    2009-04-26

    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.

  20. Role of metastable atoms in the propagation of atmospheric pressure dielectric barrier discharge jets

    SciTech Connect (OSTI)

    Li Qing; Zhu Ximing; Li Jiangtao; Pu Yikang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2010-02-15

    In the experiment of plasma jets generated in a tube dielectric barrier discharge configuration, three distinguishable modes, namely, laminar, transition, and turbulent jet modes, have been identified. Flows of helium, neon, and argon gases shared the hydrodynamic law when their plasma jets spraying into ambient air of atmospheric pressure and room temperature. Aiming to reveal the basic processes, we propose that plasma jet length is mainly determined by reactions involving metastable atoms. These processes are responsible for the variation in plasma jet length versus gas flow rate and working gas species. To investigate this proposal in detail, we have obtained three significant experimental results, i.e., (1) the plasma jet lengths of helium, neon, and argon are different; (2) the plasma jet length of krypton slightly changes with gas flow rate, with three modes indistinguishable; and (3) there are large differences between optical emission spectra of helium, neon, argon, and krypton flow gases. These observations are in good agreement with our proposal.

  1. Fossil turbulence and fossil turbulence waves can be dangerous

    E-Print Network [OSTI]

    Carl H Gibson

    2012-11-25

    Turbulence is defined as an eddy-like state of fluid motion where the inertial-vortex forces of the eddies are larger than any other forces that tend to damp the eddies out. By this definition, turbulence always cascades from small scales where vorticity is created to larger scales where turbulence fossilizes. Fossil turbulence is any perturbation in a hydrophysical field produced by turbulence that persists after the fluid is no longer turbulent at the scale of the perturbation. Fossil turbulence patterns and fossil turbulence waves preserve and propagate energy and information about previous turbulence. Ignorance of fossil turbulence properties can be dangerous. Examples include the Osama bin Laden helicopter crash and the Air France 447 Airbus crash, both unfairly blamed on the pilots. Observations support the proposed definitions, and suggest even direct numerical simulations of turbulence require caution.

  2. Top Jets at the LHC

    E-Print Network [OSTI]

    Almeida, L.G.

    2009-01-01

    Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladWIS/17/08-SEPT-DPP Top Jets at the LHC Leandro G. Almeidareconstructed as a single jet, a “top-jet”. The most basic “

  3. Particle Physics Phenomenology 8. QCD jets and jet algorithms

    E-Print Network [OSTI]

    Sjöstrand, Torbjörn

    Particle Physics Phenomenology 8. QCD jets and jet algorithms Torbj¨orn Sj¨ostrand Department rotationally symmetric. SppS (CERN): need to separate beam jets from highp ones. First solution: cone jets" infrared safe return to UA1 cone algorithm. Torbj¨orn Sj¨ostrand PPP 8: QCD jets and jet algorithms slide 2

  4. Circular permutant GFP insertion folding reporters

    DOE Patents [OSTI]

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

    2011-06-14

    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. Circular permutant GFP insertion folding reporters

    DOE Patents [OSTI]

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

    2008-06-24

    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.

  6. Circular permutant GFP insertion folding reporters

    DOE Patents [OSTI]

    Waldo, Geoffrey S; Cabantous, Stephanie

    2013-02-12

    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.

  7. Circular permutant GFP insertion folding reporters

    DOE Patents [OSTI]

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2013-04-16

    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.

  8. ATMOSPHERIC CIRCULATION OF BROWN DWARFS: JETS, VORTICES, AND TIME VARIABILITY

    SciTech Connect (OSTI)

    Zhang, Xi; Showman, Adam P.

    2014-06-10

    A variety of observational evidence demonstrates that brown dwarfs exhibit active atmospheric circulations. In this study we use a shallow-water model to investigate the global atmospheric dynamics in the stratified layer overlying the convective zone on these rapidly rotating objects. We show that the existence and properties of the atmospheric circulation crucially depend on key parameters including the energy injection rate and radiative timescale. Under conditions of strong internal heat flux and weak radiative dissipation, a banded flow pattern comprised of east-west jet streams spontaneously emerges from the interaction of atmospheric turbulence with the planetary rotation. In contrast, when the internal heat flux is weak and/or radiative dissipation is strong, turbulence injected into the atmosphere damps before it can self-organize into jets, leading to a flow dominated by transient eddies and isotropic turbulence instead. The simulation results are not very sensitive to the form of the forcing. Based on the location of the transition between jet-dominated and eddy-dominated regimes, we suggest that many brown dwarfs may exhibit atmospheric circulations dominated by eddies and turbulence (rather than jets) due to the strong radiative damping on these worlds, but a jet structure is also possible under some realistic conditions. Our simulated light curves capture important features from observed infrared light curves of brown dwarfs, including amplitude variations of a few percent and shapes that fluctuate between single-peak and multi-peak structures. More broadly, our work shows that the shallow-water system provides a useful tool to illuminate fundamental aspects of the dynamics on these worlds.

  9. Fully Developed Turbulent Mixing in an Annular Sector

    SciTech Connect (OSTI)

    Lim, Hyun-Kyung; Zhou, Yijie; de Almeida, Valmor F; Glimm, James G

    2014-01-01

    We review recent progress on the characterization of turbulent mixing fluid flow and relate these ideas to high-speed, two-phase Couette flow with application to mixing in a centrifugal contactor. The general ideas are more broadly applicable and have been applied to the study of Rayleigh-Taylor and Richtmyer-Meshkov fluid mixing, combustion in the engine of a scram jet and the analysis of inertial confinement pellet simulations.

  10. Circular Chromatic Ramsey Number Kyle F. Jao

    E-Print Network [OSTI]

    West, Douglas B.

    Circular Chromatic Ramsey Number Kyle F. Jao , Claude Tardif , Douglas B. West , Xuding Zhu, the circular chromatic Ramsey number Rc (F, G) is the infimum of c(H) over graphs H such that every red of a Ramsey problem for the families of homomorphic images of F and G. Letting zk = 3 - 2-k, we prove that zk

  11. 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

  12. Coherent Structures in Turbulent Flows: Experimental Studies on the Turbulence of Multiphase Plumes and Tidal Vortices 

    E-Print Network [OSTI]

    Bryant, Duncan Burnette

    2011-08-08

    stream_source_info BRYANT-DISSERTATION.pdf.txt stream_content_type text/plain stream_size 163756 Content-Encoding ISO-8859-1 stream_name BRYANT-DISSERTATION.pdf.txt Content-Type text/plain; charset=ISO-8859..., the turbulent energy spectra in inertial particle plumes followed the same modulation as the bubble plumes. PIV experiments from the tidal starting-jet vortices detail the influence of a finite channel length using identified vortice. The results show...

  13. 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

  14. A swirling jet under the influence of a coaxial flow

    SciTech Connect (OSTI)

    Giannadakis, A.; Perrakis, K.; Panidis, Th. [University of Patras, Department of Mechanical Engineering and Aeronautics, Laboratory of Applied Thermodynamics (Greece)

    2008-09-15

    The recirculating flow field generated by a swirling jet and a coaxial annular stream entering a pipe is investigated with the use of 2D-DPIV. Parametric change of inlet flow rates (constant tangential injection with change of annular flow and vice versa) is being considered in order to study the mean and turbulent flow field. A recirculation bubble stabilized close to the swirler exit is the dominating feature of the interaction between the inner swirling jet and the annular stream. Results are discussed in terms of bubble topology and dynamics on the basis of a modified Rossby number that appears to describe the trends of the complex flow field. (author)

  15. Experimental study on confined two-phase jets

    SciTech Connect (OSTI)

    Levy, Y.; Albagli, D. )

    1991-09-01

    The basic mixing phenomena in confined, coaxial, particle-laden turbulent flows are studied within the scope of ram combustor research activities. Cold-flow experiments in a relatively simple configuration of confined, coaxial two-phase jets provided both qualitative and quantitative insight on the multiphase mixing process. Pressure, tracer gas concentration, and two-phase velocity measurements revealed that unacceptably long ram combustors are needed for complete confined jet mixing. Comparison of the experimental results with a previous numerical simulation displayed a very good agreement, indicating the potential of the experimental facility for validation of computational parametric studies. 38 refs.

  16. Substructure of Boosted Jets

    E-Print Network [OSTI]

    Ehud Duchovni

    2013-05-21

    Jets with transverse energy of few TeV are becoming now common in LHC data. Most of these jets are produced by QCD processes and some from the collimated decay of highly boosted objects like W, Z, H0 and top-quark. The study of such QCD jets may shed light on QCD showering processes and the identification of the jets coming from decays may test the Standard Model under extreme conditions and may also provide the first hints for Physics Beyond the Standard Model. A short review of jet algorithms, Correction procedures for pile-up effects and commonly used substructure observables are described.

  17. Experimental study of turbulent flame kernel propagation

    SciTech Connect (OSTI)

    Mansour, Mohy [National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Peters, Norbert; Schrader, Lars-Uve [Institute of Combustion Technology, Aachen (Germany)

    2008-07-15

    Flame kernels in spark ignited combustion systems dominate the flame propagation and combustion stability and performance. They are likely controlled by the spark energy, flow field and mixing field. The aim of the present work is to experimentally investigate the structure and propagation of the flame kernel in turbulent premixed methane flow using advanced laser-based techniques. The spark is generated using pulsed Nd:YAG laser with 20 mJ pulse energy in order to avoid the effect of the electrodes on the flame kernel structure and the variation of spark energy from shot-to-shot. Four flames have been investigated at equivalence ratios, {phi}{sub j}, of 0.8 and 1.0 and jet velocities, U{sub j}, of 6 and 12 m/s. A combined two-dimensional Rayleigh and LIPF-OH technique has been applied. The flame kernel structure has been collected at several time intervals from the laser ignition between 10 {mu}s and 2 ms. The data show that the flame kernel structure starts with spherical shape and changes gradually to peanut-like, then to mushroom-like and finally disturbed by the turbulence. The mushroom-like structure lasts longer in the stoichiometric and slower jet velocity. The growth rate of the average flame kernel radius is divided into two linear relations; the first one during the first 100 {mu}s is almost three times faster than that at the later stage between 100 and 2000 {mu}s. The flame propagation is slightly faster in leaner flames. The trends of the flame propagation, flame radius, flame cross-sectional area and mean flame temperature are related to the jet velocity and equivalence ratio. The relations obtained in the present work allow the prediction of any of these parameters at different conditions. (author)

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

    E-Print Network [OSTI]

    Curtis Struck; Daniel C. Smith

    1999-07-29

    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)

  19. Terascale Direct Numerical Simulations of Turbulent Combustion: Capabilities and Limits (PReSS Talk)

    SciTech Connect (OSTI)

    Yoo, Chun Sang

    2009-03-26

    The rapid growth in computational capabilities has provided great opportunities for direct numerical simulations (DNS) of turbulent combustion, a type of simulations without any turbulence model. With the help of terascale high performance supercomputing (HPC) resources, we are now able to provide fundamental insight into turbulence-chemistry interaction in simple laboratory-scale turbulent flames with detailed chemistry using three-dimensional (3D) DNS. However, the actual domain size of 3D-DNS is still limited within {approx} O(10 cm{sup 3}) due to its tremendously high grid resolution required to resolve the smallest turbulent length scale as well as flame structures. Moreover, 3D-DNS will require more computing powers to investigate next-generation engines, of which operating conditions will be characterized by higher pressures, lower temperatures, and higher levels of dilution. In this talk, I will discuss the capabilities and limits of DNS of turbulent combustion and present some results of ignition/extinction characteristics of a highly diluted hydrogen flame counter-flowing against heated air. The results of our recent 3D-DNS of a spatially-developing turbulent lifted hydrogen jet flame in heated coflow will also be presented. The 3D-DNS was performed at a jet Reynolds number of 11,000 with {approx} 1 billion grid points, which required 3.5 million CPU hours on Cray XT3/XT4 at Oak Ridge National Laboratories.

  20. Kilohertz PIV/PLMS of low-gravity turbulent flames in a drop tower I.G. Boxx, C.A. Idicheria, N.T. Clemens(1)

    E-Print Network [OSTI]

    Clemens, Noel T.

    -flame in a crossflow (JFICF). The system developed represents a major advance in the state of the art of microgravity to examine a hydrogen jet-flame in a crossflow (momentum flux ratio of 7, Re = 900) under normal and low. INTRODUCTION The turbulent jet-flame in a crossflow (JFICF) is a flowfield of theoretical and applied

  1. Policy Flash 2013-27 Federal Acquisition Circular (FAC) 2005...

    Office of Environmental Management (EM)

    7 Federal Acquisition Circular (FAC) 2005-65 Policy Flash 2013-27 Federal Acquisition Circular (FAC) 2005-65 Attached is Policy Flash 2013-27 Federal Acquisition Circular (FAC)...

  2. Observations of Edge Turbulence

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

    Edge Turbulence near the X-point of Alcator C-Mod APS-2007 (1) J.L. Terry, S.J. Zweben*, B. LaBombard, I. Cziegler, O. Grulke + , D.P. Stotler* MIT - Plasma Science and Fusion...

  3. 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)

    2008-03-04

    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.

  4. PHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2013-01-01

    industrial combustion systems such as, stationary gas turbines, lean premixed and prevaporized jet engines for simulating combustion in gas turbine engines. Second, although a large body of research has been devotedPHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

  5. Diffusive radiation in one-dimensional Langmuir turbulence G. D. Fleishman1

    E-Print Network [OSTI]

    -dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular sensi- tively on the angle between the particle velocity and electric field direction. The radiation as gamma-ray bursts and collimated jets. DOI: 10.1103/PhysRevE.76.017401 PACS number s : 52.25.Os, 52.35.Ra

  6. LES/PDF based modeling of sootturbulence interactions in turbulent flames

    E-Print Network [OSTI]

    Raman, Venkat

    number density function. This LES/PDF approach is then used to simulate a turbulent natural gas jet strong correlation between the gas phase composition and soot moments. Ó 2012 The Combustion Institute and the gas-phase composition are often neglected. In this case, the PDF is written as the product of the mar

  7. Modeling shock unsteadiness in shock/turbulence interaction Krishnendu Sinha*, Krishnan Mahesh and Graham V. Candler

    E-Print Network [OSTI]

    Mahesh, Krishnan

    flows, e.g. deflected control surfaces of high-speed vehicles and inlet of scram jet engines. Shock and Graham V. Candler Aerospace Engineering and Mechanics & Army HPC Research Center University of Minnesota and Astro- nautics, Inc. with permission. Engineering prediction of shock/turbulence inter- action relies

  8. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect (OSTI)

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide evidence that the leading points model can provide useful predictions of turbulent flame speed over a wide range of operating conditions and flow geometries.

  9. Diffusive radiation in Langmuir turbulence produced by jet shocks

    E-Print Network [OSTI]

    Fleishman, Gregory D

    2007-01-01

    Anisotropic distributions of charged particles including two-stream distributions give rise to generation of either stochastic electric fields (in the form of Langmuir waves, Buneman instability) or random quasi-static magnetic fields (Weibel and filamentation instabilities) or both. These two-stream instabilities are known to play a key role in collisionless shock formation, shock-shock interactions, and shock-induced electromagnetic emission. This paper applies the general non-perturbative stochastic theory of radiation to study electromagnetic emission produced by relativistic particles, which random walk in the stochastic electric fields of the Langmuir waves. This analysis takes into account the cumulative effect of uncorrelated Langmuir waves on the radiating particle trajectory giving rise to angular diffusion of the particle, which eventually modifies the corresponding radiation spectra. We demonstrate that the radiative process considered is probably relevant for emission produced in various kinds of...

  10. CONTROL OF COHERENT STRUCTURE IN COAXIAL SWIRLING TURBULENT JETS

    E-Print Network [OSTI]

    Lee, Wonjoong

    2008-01-01

    mechanical excitation device are designed and fabricated for the low speed and plain perturbations. The major system components consist of concentric subsonic nozzles, swirl generators, and the excitation devices with straight lobes. The experiments...

  11. Jet studies with STAR at RHIC: jet algorithms, jet shapes, jets in AA

    E-Print Network [OSTI]

    Jan Kapitan; for the STAR Collaboration

    2011-11-08

    Hard scattered partons are predicted to be well calibrated probes of the hot and dense medium produced in heavy ion collisions. Interactions of these partons with the medium w ill result in modifications of internal jet structure in Au+Au events compared to that observed in the p+p/d+Au reference. Full jet reconstruction is a promising tool to measu re these effects without the significant biases present in measurements with high-$\\pT$ hadrons. One of the most significant challenges for jet reconstruction in the heavy ion environment comes from the correct characterization of the background fluctuations. The jet mome ntum irresolution due to background fluctuations has to be understood in order to recover the correct jet spectrum. Recent progress in jet reconstruction methodology is discu ssed, as well as recent measurements from p+p, d+Au and Au+Au collisions at $\\sqrt{s_\\mathrm{NN}}=200 \\gev$.

  12. Reconstructed Jets at RHIC

    E-Print Network [OSTI]

    Sevil Salur

    2010-04-30

    To precisely measure jets over a large background such as pile up in high luminosity p+p collisions at LHC, a new generation of jet reconstruction algorithms is developed. These algorithms are also applicable to reconstruct jets in the heavy ion environment where large event multiplicities are produced. Energy loss in the medium created in heavy ion collisions are already observed indirectly via inclusive hadron distributions and di-hadron correlations. Jets can be used to study this energy loss in detail with reduced biases. We review the latest results on jet-medium interactions as seen in A+A collisions at RHIC, focusing on the recent progress on jet reconstruction in heavy ion collisions.

  13. Circular dichroism of planar chiral magnetic metamaterials

    E-Print Network [OSTI]

    Circular dichroism of planar chiral magnetic metamaterials M. Decker, M. W. Klein, and M. Wegener 78002); published March 5, 2007 We propose, fabricate, and study a double-layer chiral planar

  14. Federal Acquisition Regulation; Federal Acquisition Circular...

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

    2005-37; Introduction Federal Acquisition Circular (FAC) 2005-37 List of Rules in FAC 2005-37 Item Subject I. Registry of Disaster Response Contractors II. Limiting Length of...

  15. Federal Acquisition Circular WAC) 2001-24

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

    FLASH 2004-20 July 12, 2004 Federal Acquisition Circular WAC) 2001-24 1. Incentives for Use of Performance-Based Contracting for Services (Interim) (FAR Case 2004-004) Effective...

  16. A spray-suppression model for turbulent combustion

    SciTech Connect (OSTI)

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

    2000-02-14

    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.

  17. QCD and Jet Physics

    E-Print Network [OSTI]

    B R Webber

    1994-10-12

    The current status of the QCD coupling constant $\\alpha_S$ and experimental and theoretical studies of hadronic jets are reviewed.

  18. Jets in QCD

    SciTech Connect (OSTI)

    Seymour, M.H.

    1996-02-01

    Many analyses at the collider utilize the hadronic jets that are the footprints of QCD partons. These are used both to study the QCD processes themselves and increasingly as tools to study other physics, for example top mass reconstruction. However, jets are not fundamental degrees of freedom in the theory, so we need an {ital operational} {ital jet} {ital definition} and {ital reliable} {ital methods} {ital to} {ital calculate} {ital their} {ital properties}. This talk covers both of these important areas of jet physics. {copyright} {ital 1996 American Institute of Physics.}

  19. Interpretation of extragalactic jets

    SciTech Connect (OSTI)

    Norman, M.L.

    1985-01-01

    The nature of extragalatic radio jets is modeled. The basic hypothesis of these models is that extragalatic jets are outflows of matter which can be described within the framework of fluid dynamics and that the outflows are essentially continuous. The discussion is limited to the interpretation of large-scale (i.e., kiloparsec-scale) jets. The central problem is to infer the physical parameters of the jets from observed distributions of total and polarized intensity and angle of polarization as a function of frequency. 60 refs., 6 figs.

  20. Taming jets in magnetised fluids

    E-Print Network [OSTI]

    Kosuga, Yusuke; Brummell, Nicholas

    2010-01-01

    Down right: Cancellation of stresses and quenching of Jets.to Reynolds stress driven jets, since both ?ux expulsion andTaming Jets in magnetized ?uids Y. Kosuga 1 and N. H.

  1. Multidimensional turbulence spectra -identifying properties of turbulent structures

    E-Print Network [OSTI]

    Kevlahan, Nicholas

    Sweden 2 Department of Mathematics and Statistics, McMaster University, Hamilton L8S 4K1, Canada * E turbulent structures are presented. Results from analysis of the turbulent kinetic energy in turbulent energy associated with a coherent vortex defined using different vortex identification methods

  2. Studies of the effects of curvature on dilution jet mixing

    SciTech Connect (OSTI)

    Holdeman, J.D.; Srinivasan, Ram: Reynolds, R.S.; White, C.D. Allied-Signal Aerospace Co., Phoenix, AZ )

    1992-02-01

    An analytical program was conducted using both three-dimensional numerical and empirical models to investigate the effects of transition liner curvature on the mixing of jets injected into a confined crossflow. The numerical code is of the TEACH type with hybrid numerics; it uses the power-law and SIMPLER algorithms, an orthogonal curvilinear coordinate system, and an algebraic Reynolds stress turbulence model. From the results of the numerical calculations, an existing empirical model for the temperature field downstream of single and multiple rows of jets injected into a straight rectangular duct was extended to model the effects of curvature. Temperature distributions, calculated with both the numerical and empirical models, are presented to show the effects of radius of curvature and inner and outer wall injection for single and opposed rows of cool dilution jets injected into a hot mainstream flow. 27 refs.

  3. Quantum ghost imaging through turbulence

    E-Print Network [OSTI]

    Dixon, P. Ben

    We investigate the effect of turbulence on quantum ghost imaging. We use entangled photons and demonstrate that for a specific experimental configuration the effect of turbulence can be greatly diminished. By decoupling ...

  4. QCD Jets and Parton Showers

    E-Print Network [OSTI]

    Bryan R. Webber

    2010-09-29

    I discuss the calculation of QCD jet rates in e+e- annihilation as a testing ground for parton shower simulations and jet finding algorithms.

  5. The effects of obstacle geometry on jet mixing in releases of silane 

    E-Print Network [OSTI]

    Sposato, Christina F

    2000-01-01

    Releases of silane into air and the effects of obstacles were modeled with the Computational Fluid Dynamics (CFD) code, FLUENT. First the CFD code simulated the release of a free turbulent jet of silane into air to assure that the code agreed...

  6. Structure and Mixing Characterization of Variable Density Transverse Jet Flows

    E-Print Network [OSTI]

    Gevorkyan, Levon

    2015-01-01

    4 Transverse Jet Mixing . . . . . . . . . . . . . . . . . .Jet TrajectoryTransverse Jet Structure and

  7. Nonaxisymmetric Poynting Jets

    E-Print Network [OSTI]

    Samuel E. Gralla; Ted Jacobson

    2015-07-29

    The relativistic plasma jets from a misaligned black hole-accretion disk system will not be axially symmetric. Here we analyze nonaxisymmetric, stationary, translation invariant jets in the force-free approximation where the field energy dominates the particle energy. We derive a stream equation for these configurations involving the flux function $\\psi$ for the transverse magnetic field, the linear velocity $v(\\psi)$ of field lines along the jet, and the longitudinal magnetic field $B_z(\\psi)$. The equations can be completely solved when $|v|=1$, and when $|v|jet that has vanishing electromagnetic pressure $\\tfrac{1}{2}(B^2-E^2)$ and requires no external pressure for confinement. We prove that such self-confinement is impossible when $B^2>E^2$. Finally, we write down specific solutions approximating numerical results for the nonaxisymmetric jet produced by a spinning black hole in an external, misaligned magnetic field.

  8. Wave turbulent statistics in non-weak wave turbulence

    E-Print Network [OSTI]

    Naoto Yokoyama

    2011-05-08

    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.

  9. Particle Physics Phenomenology 8. QCD jets and jet algorithms

    E-Print Network [OSTI]

    Sjöstrand, Torbjörn

    Particle Physics Phenomenology 8. QCD jets and jet algorithms Torbj¨orn Sj¨ostrand Department k. All rotationally symmetric. SppS (CERN): need to separate beam jets from highp ones. First solution: cone jets in (, ) space, e.g. UA1. (Second solution: clustering like Durham

  10. Modeling jet and outflow feedback during star cluster formation

    SciTech Connect (OSTI)

    Federrath, Christoph; Schrön, Martin; Banerjee, Robi; Klessen, Ralf S.

    2014-08-01

    Powerful jets and outflows are launched from the protostellar disks around newborn stars. These outflows carry enough mass and momentum to transform the structure of their parent molecular cloud and to potentially control star formation itself. Despite their importance, we have not been able to fully quantify the impact of jets and outflows during the formation of a star cluster. The main problem lies in limited computing power. We would have to resolve the magnetic jet-launching mechanism close to the protostar and at the same time follow the evolution of a parsec-size cloud for a million years. Current computer power and codes fall orders of magnitude short of achieving this. In order to overcome this problem, we implement a subgrid-scale (SGS) model for launching jets and outflows, which demonstrably converges and reproduces the mass, linear and angular momentum transfer, and the speed of real jets, with ?1000 times lower resolution than would be required without the SGS model. We apply the new SGS model to turbulent, magnetized star cluster formation and show that jets and outflows (1) eject about one-fourth of their parent molecular clump in high-speed jets, quickly reaching distances of more than a parsec, (2) reduce the star formation rate by about a factor of two, and (3) lead to the formation of ?1.5 times as many stars compared to the no-outflow case. Most importantly, we find that jets and outflows reduce the average star mass by a factor of ? three and may thus be essential for understanding the characteristic mass of the stellar initial mass function.

  11. Thermographic analysis of turbulent non-isothermal water boundary layer

    E-Print Network [OSTI]

    Znamenskaya, Irina A

    2015-01-01

    The paper is devoted to the investigation of the turbulent water boundary layer in the jet mixing flows using high-speed infrared (IR) thermography. Two turbulent mixing processes were studied: a submerged water jet impinging on a flat surface and two intersecting jets in a round disc-shaped vessel. An infrared camera (FLIR Systems SC7700) was focused on the window transparent for IR radiation; it provided high-speed recordings of heat fluxes from a thin water layer close to the window. Temperature versus time curves at different points of water boundary layer near the wall surface were acquired using the IR camera with the recording frequency of 100 Hz. The time of recording varied from 3 till 20 min. The power spectra for the temperature fluctuations at different points on the hot-cold water mixing zone were calculated using the Fast Fourier Transform algorithm. The obtained spectral behavior was compared to the Kolmogorov "-5/3 spectrum" (a direct energy cascade) and the dual-cascade scenario predicted for...

  12. Characterization of Relativistic MHD Turbulence

    E-Print Network [OSTI]

    Garrison, David

    2015-01-01

    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.

  13. 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)

    2012-09-20

    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.

  14. Static magnetic fields enhance turbulence

    E-Print Network [OSTI]

    Pothérat, Alban

    2015-01-01

    More often than not, turbulence occurs under the influence of external fields, mostly rotation and magnetic fields generated either by planets, stellar objects or by an industrial environment. Their effect on the anisotropy and the dissipative behaviour of turbulence is recognised but complex, and it is still difficult to even tell whether they enhance or dampen turbulence. For example, externally imposed magnetic fields suppress free turbulence in electrically conducting fluids (Moffatt 1967), and make it two-dimensional (2D) (Sommeria & Moreau 1982); but their effect on the intensity of forced turbulence, as in pipes, convective flows or otherwise, is not clear. We shall prove that since two-dimensionalisation preferentially affects larger scales, these undergo much less dissipation and sustain intense turbulent fluctuations. When higher magnetic fields are imposed, quasi-2D structures retain more kinetic energy, so that rather than suppressing forced turbulence, external magnetic fields indirectly enha...

  15. SHOCK CORRUGATION BY RAYLEIGH-TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS

    SciTech Connect (OSTI)

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2014-08-10

    Afterglow jets are Rayleigh-Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh-Taylor calculations using more physical cooling models.

  16. Angular Scaling In Jets

    SciTech Connect (OSTI)

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

    2012-02-17

    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.

  17. Nonaxisymmetric Poynting Jets

    E-Print Network [OSTI]

    Gralla, Samuel E

    2015-01-01

    The relativistic plasma jets from a misaligned black hole-accretion disk system will not be axially symmetric. Here we analyze nonaxisymmetric, stationary, translation invariant jets in the force-free approximation where the field energy dominates the particle energy. We derive a stream equation for these configurations involving the flux function $\\psi$ for the transverse magnetic field, the linear velocity $v(\\psi)$ of field lines along the jet, and the longitudinal magnetic field $B_z(\\psi)$. The equations can be completely solved when $|v|=1$, and when $|v|E^2$. Finally, we write down specific solutions approximating numerical results for the nonaxisymmetric jet produced by a spinning black hole in an external, misaligned magnetic field.

  18. GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM

    SciTech Connect (OSTI)

    Cho, Jungyeon; Yoo, Hyunju

    2012-11-10

    Turbulence dynamo deals with the amplification of a seed magnetic field in a turbulent medium and has been studied mostly for uniform or spatially homogeneous seed magnetic fields. However, some astrophysical processes (e.g., jets from active galaxies, galactic winds, or ram-pressure stripping in galaxy clusters) can provide localized seed magnetic fields. In this paper, we numerically study amplification of localized seed magnetic fields in a turbulent medium. Throughout the paper, we assume that the driving scale of turbulence is comparable to the size of the system. Our findings are as follows. First, turbulence can amplify a localized seed magnetic field very efficiently. The growth rate of magnetic energy density is as high as that for a uniform seed magnetic field. This result implies that magnetic field ejected from an astrophysical object can be a viable source of a magnetic field in a cluster. Second, the localized seed magnetic field disperses and fills the whole system very fast. If turbulence in a system (e.g., a galaxy cluster or a filament) is driven at large scales, we expect that it takes a few large-eddy turnover times for the magnetic field to fill the whole system. Third, growth and turbulence diffusion of a localized seed magnetic field are also fast in high magnetic Prandtl number turbulence. Fourth, even in decaying turbulence, a localized seed magnetic field can ultimately fill the whole system. Although the dispersal rate of the magnetic field is not fast in purely decaying turbulence, it can be enhanced by an additional forcing.

  19. Polymer Stretching by Turbulence

    SciTech Connect (OSTI)

    Chertkov, Michael

    2000-05-15

    The stretching of a polymer chain by a large-scale chaotic flow is considered. The steady state which emerges as a balance of the turbulent stretching and anharmonic resistance of the chain is quantitatively described, i.e., the dependency on the flow parameters (Lyapunov exponent statistics) and the chain characteristics (the number of beads and the interbead elastic potential) is made explicit. (c) 2000 The American Physical Society.

  20. Few-Freedom Turbulence

    E-Print Network [OSTI]

    B. V. Chirikov; V. G. Davidovsky

    2000-06-15

    The results of numerical experiments on the structure of chaotic attractors in the Khalatnikov - Kroyter model of two freedoms are presented. This model was developed for a qualitative description of the wave turbulence of the second sound in helium. The attractor dimension, size, and the maximal Lyapunov exponent in dependence on the single dimensionless parameter $F$ of the model are found and discussed. The principal parameter $F$ is similar to the Reynolds number in hydrodynamic turbulence. We were able to discern four different attractors characterized by a specific critical value of the parameter ($F=F_{cr}$), such that the attractor exists for $F>F_{cr}$ only. A simple empirical relation for this dependence on the argument ($F-F_{cr}$) is presented which turns out to be universal for different attractors with respect to the dimension and dimensionless Lyapunov exponents. Yet, it differs as to the size of attractor. In the main region of our studies the dependence of all dimensionless characteristics of the chaotic attractor on parameter $F$ is very slow (logarithmic) which is qualitatively different as compared to that of a multi-freedom attractor, e.g., in hydrodynamic turbulence (a power law). However, at very large $F\\sim 10^7$ the transition to a power-law dependence has been finally found, similar to the multi-freedom attractor. Some unsolved problems and open questions are also discussed.

  1. Numerical and experimental modeling of mixing of impinging jets radially injected into crossflow

    E-Print Network [OSTI]

    Kartaev, Evgeniy; Ktalkherman, Marat

    2014-01-01

    In some chemical processes, the formation of the counter flow in the colliding-jets regime is the most promising phenomenon if there is a need of fast quenching of an obtained product [1]. Particularly this method can be used to control disperse and phase composition of the final product. The complex calculation and experimental research of the counter collision and mixing of the circular argon jet and aluminum steams at 2000 K, and a relative cold argon jet (1000 K) is presented in [2]. It is shown there that the counter quenching regime enables to control particles grow owing to the flow dilution with the quenching jet and variation of the temperature drop rate.

  2. POLICY FLASH 2015-21 - Federal Acquisition Circulars (FACs) 2005...

    Office of Environmental Management (EM)

    1 - Federal Acquisition Circulars (FACs) 2005-79, 2005-80 & 2005-81 POLICY FLASH 2015-21 - Federal Acquisition Circulars (FACs) 2005-79, 2005-80 & 2005-81 DATE: April 14, 2015 TO:...

  3. POLICY FLASH 2015-24 - Federal Acquisition Circular (FAC) 2005...

    Office of Environmental Management (EM)

    4 - Federal Acquisition Circular (FAC) 2005-82 POLICY FLASH 2015-24 - Federal Acquisition Circular (FAC) 2005-82 DATE: May 11, 2015 TO: Procurement DirectorsContracting Officers...

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

    Energy Savers [EERE]

    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...

    Energy Savers [EERE]

    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. STREAMWISE AND CROSSFLOW INSTABILITIES ON INCLINED CIRCULAR CYLINDERS

    E-Print Network [OSTI]

    STREAMWISE AND CROSSFLOW INSTABILITIES ON INCLINED CIRCULAR CYLINDERS S. J. Garrett , J. P: Turbine blades, swept cylinder, streamwise & crossflow instabilities Abstract Observations of streamwise and crossflow insta- bilities on swept circular cylinders over a range of inclinations are presented

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

    E-Print Network [OSTI]

    Pontaza, Juan Pablo

    2013-02-22

    -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...

  8. Chaotic self-sustaining structure embeded in turbulent-laminar interface

    E-Print Network [OSTI]

    Teramura, Toshiki

    2015-01-01

    An iterface structure between turbulence and laminar flow is investigated in two-dimensional channel flow. This spatially localized structure not only sustains itself, but also converts laminar state into turbulence actively. In other words, this coherent structure has a functionality to generate inhomogeneity by its inner dynamics. The dynamics of this functional coherent structure is isolated using the filtered simulation, and a physical perspective of its dynamics is summarized in a phenomenological model called an "ejection-jet" cycle, which includes multiscale interaction process.

  9. Chaotic self-sustaining structure embeded in turbulent-laminar interface

    E-Print Network [OSTI]

    Toshiki Teramura; Sadayoshi Toh

    2015-03-16

    An iterface structure between turbulence and laminar flow is investigated in two-dimensional channel flow. This spatially localized structure not only sustains itself, but also converts laminar state into turbulence actively. In other words, this coherent structure has a functionality to generate inhomogeneity by its inner dynamics. The dynamics of this functional coherent structure is isolated using the filtered simulation, and a physical perspective of its dynamics is summarized in a phenomenological model called an "ejection-jet" cycle, which includes multiscale interaction process.

  10. Eddy fluxes in baroclinic turbulence

    E-Print Network [OSTI]

    Thompson, Andrew F.

    2006-01-01

    cant dissipation of tidal energy in the deep ocean inferred2006: An estimate of tidal energy lost to turbulence at the

  11. Sandia Energy - Applied Turbulent Combustion

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

    and they form the basis for the creation of validated submodels that bridge fundamental energy sciences with applied device engineering and optimization. Turbulent-combustion-lab...

  12. Disjoint BoundaryBoundary Paths in Critical Circular Planar Networks

    E-Print Network [OSTI]

    Morrow, James A.

    Disjoint Boundary­Boundary Paths in Critical Circular Planar Networks Ryan Sturgell December 8 that in a critical circular planar network every interior vertex has three disjoint paths to the boundary. 1, 1998 Abstract This paper explores some properties of critical circular planar net­ works. The main

  13. The first calculation of fractional jets

    E-Print Network [OSTI]

    Bertolini, Daniele

    In collider physics, jet algorithms are a ubiquitous tool for clustering particles into discrete jet objects. Event shapes offer an alternative way to characterize jets, and one can define a jet multiplicity event shape, ...

  14. Jet propulsion without inertia

    E-Print Network [OSTI]

    Saverio E. Spagnolie; Eric Lauga

    2010-05-04

    A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies, and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented, and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e. jetting) surfaces are considered, and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate, and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria.

  15. Evidence for internal structures of spiral turbulence

    E-Print Network [OSTI]

    2009-12-21

    Dec 22, 2009 ... ary laminar-turbulent pattern in plane Couette flow. ... flow internal to the turbulent and laminar spirals, and unique ... 2 ( is the fluid density).

  16. 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...

  17. Simulation of lean premixed turbulent combustion

    E-Print Network [OSTI]

    2008-01-01

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

  18. Effect of wall conduction on heat transfer for turbulent flow in a circular tube 

    E-Print Network [OSTI]

    Lin, Yie-Kuang

    1980-01-01

    ) then ~ y+) 1+ g-7 x? ~? CmR. ~&r I'g g x I, & " pig. p()c)} f so as tm Lr=b rnn ? y Z. C R?(v)e~P( ? P X ) ~ M o (14) 2 where P =1, b. = (i+1) w. m m, ' i i+1 + + F (x )= (1 ? exp(-P x ) }/P 0 Ill Itl + . +i + F, (x )= (x -iF, (x )}/P...") &)(. ? Gz & ( 0 0 (K, ( L ) Zi( ~ )+ Z, (" L ) K, ( L')j/ J (i+2-, 7. X )C. S Z X dX (23) Heat Exchan e Between the Fluid and the Solid Wall (i) Constant Heat Flux The following relations are applicable at the fluid-solid interface (24) Using Eq...

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

    E-Print Network [OSTI]

    Lakshmipathy, Sunil

    2006-04-12

    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...

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

    E-Print Network [OSTI]

    Reyes, Dasia Ann

    2009-05-15

    -Stokes (RANS) method. Preliminary investigations of PANS show promising re-sults but there still exist computational and physical issues that must be addressed.This study investigates the performance of the PANS method for ow past acylinder at a Reynolds number...

  1. Circular, confined distribution for charged particle beams

    DOE Patents [OSTI]

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

    1995-01-01

    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.

  2. Circular, confined distribution for charged particle beams

    DOE Patents [OSTI]

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

    1995-11-21

    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.

  3. Gudrun's (NLO) list pp->WW jet

    E-Print Network [OSTI]

    Huston, Joey

    Gudrun's (NLO) list 2->3 pp->WW jet pp->VVV pp->H + 2 jets 2->4 pp->4 jets pp->tT + 2jets p->tT bB pp->V+ 3 jets pp->VV + 2 jets pp->VVV + jet pp->WW bB From technology point-of-view start with massless cases such as + 2 jets then add progressively more difficult calculations (additional scales

  4. Circular zig-zag scan video format

    DOE Patents [OSTI]

    Peterson, C. Glen (Los Alamos, NM); Simmons, Charles M. (Los Alamos, NM)

    1992-01-01

    A circular, ziz-zag scan for use with vidicon tubes. 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.

  5. Jets in Particle Colliders Andrew Wong!

    E-Print Network [OSTI]

    Budker, Dmitry

    Jets in Particle Colliders Andrew Wong! #12;Topics · What are jets? · How are they produced? · What do we use to study jets? #12;What are jets? · Bunch of different jets #12;Pretty picture! #12;What's in a jet? · Hadrons ­ Kaons, Pions, Protons, Neutrons · Leptons ­ Mainly electrons and muons · These have

  6. Organic vapor jet printing system

    DOE Patents [OSTI]

    Forrest, Stephen R

    2012-10-23

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

  7. Jet Fuel from Microalgal Lipids

    SciTech Connect (OSTI)

    Not Available

    2006-07-01

    A fact sheet on production of jet fuel or multi-purpose military fuel from lipids produced by microalgae.

  8. Advances in compressible turbulent mixing

    SciTech Connect (OSTI)

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

    1992-01-01

    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.

  9. Energy spectra in bubbly turbulence

    E-Print Network [OSTI]

    Prakash, Vivek N; Ramos, Fabio Ernesto Mancilla; Tagawa, Yoshiyuki; Lohse, Detlef; Sun, Chao

    2013-01-01

    We conduct experiments in a turbulent bubbly flow to study the unknown nature of the transition between the classical -5/3 energy spectrum scaling for a single-phase turbulent flow and the -3 scaling for a swarm of bubbles rising in a quiescent liquid and of bubble-dominated turbulence. The bubblance parameter, b, which measures the ratio of the bubble-induced kinetic energy to the kinetic energy induced by the turbulent liquid fluctuations before bubble injection, is used to characterise the bubbly flow. We vary b from $b = \\infty$ (pseudo-turbulence) to b = 0 (single-phase flow) over 2-3 orders of magnitude: ~O(0.01, 0.1, 5) to study its effect on the turbulent energy spectrum and liquid velocity fluctuations. The experiments are conducted in a multi-phase turbulent water tunnel with air bubbles of diameters 2-4 mm and 3-5 mm. An active-grid is used to generate nearly homogeneous and isotropic turbulence in the liquid flow. The liquid speeds and gas void fractions are varied to achieve the above mentioned b...

  10. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-01-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  11. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-08-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  12. Particle Multiplicity in Jets and Sub-jets with Jet Axis from Color Current

    E-Print Network [OSTI]

    Wlofgang Ochs; Redamy Perez Ramos

    2008-07-07

    We study the particle multiplicity in a jet or sub-jet as derived from an energy-multiplicity 2-particle correlation. This definition avoids the notion of a globally fixed jet axis and allows for the study of smaller jet cone openings in a more stable way. The results are sensitive to the mean color current $_{A_0} $ in the jet from primary parton $A_0$ which takes into account intermediate partonic processes in the sub-jet production where $C_F_{A_0} jet axis definition are computed for multiplicities in sub-jets with different opening angles and energies by including contributions from the Modified LLA (MLLA) and Next-to-MLLA to the leading order QCD results.

  13. BARYON LOADING OF ACTIVE GALACTIC NUCLEUS JETS MEDIATED BY NEUTRONS

    SciTech Connect (OSTI)

    Toma, K.; Takahara, F.

    2012-08-01

    Plasmas of geometrically thick, black hole (BH) accretion flows in active galactic nuclei (AGNs) are generally collisionless for protons, and involve magnetic field turbulence. Under such conditions a fraction of protons can be accelerated stochastically and create relativistic neutrons via nuclear collisions. These neutrons can freely escape from the accretion flow and decay into protons in the dilute polar region above the rotating BH to form relativistic jets. We calculate geometric efficiencies of the neutron energy and mass injections into the polar region, and show that this process can deposit luminosity as high as L{sub j}{approx}2 Multiplication-Sign 10{sup -3} M-dot c{sup 2} and mass loading M-dot{sub j}{approx}6 Multiplication-Sign 10{sup -4} M-dot for the case of the BH mass M {approx} 10{sup 8} M{sub Sun }, where M-dot is the mass accretion rate. The terminal Lorentz factors of the jets are {Gamma} {approx} 3, and they may explain the AGN jets having low luminosities. For higher luminosity jets, which can be produced by additional energy inputs such as Poynting flux, the neutron decay still can be a dominant mass loading process, leading to, e.g., {Gamma} {approx} 50 for L{sub j,tot}{approx}3 Multiplication-Sign 10{sup -2} M-dot c{sup 2}.

  14. Instabilities of rotating jets

    E-Print Network [OSTI]

    Zahniser, Russell, 1982-

    2004-01-01

    When a jet of water is in free fall, it rapidly breaks up into drops, since a cylinder of water is unstable. This and other problems involving the form of a volume of water bound by surface tension have yielded a wealth ...

  15. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01

    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.

  16. Hadron Correlation in Jets

    E-Print Network [OSTI]

    Rudolph C. Hwa

    2007-01-18

    We review some recent experimental and theoretical work on the correlation among hadrons produced at intermediate $p_T$ at RHIC. The topics include: forward and backward asymmetry with and without trigger at mid-rapidity, associated-particle distribution on the near side, the $\\Omega$ puzzle and its solution, associated particles on the away side, and two-jet recombination at LHC.

  17. The Effect of Magnetic Turbulence Energy Spectral

    E-Print Network [OSTI]

    Ng, Chung-Sang

    The Effect of Magnetic Turbulence Energy Spectral Scaling on the Heating of the Solar Wind C. S. Ng), Kraichnan (1965) #12;Solar wind turbulence model The steady state solar wind turbulence model developed wind with uniform speed Vsw 1D (radial position r) Turbulence characterized by two fields

  18. Interacting Jets from Binary Protostars

    E-Print Network [OSTI]

    G. C. Murphy; T. Lery; S. O'Sullivan; D. Spicer; F. Bacciotti; A. Rosen

    2007-11-20

    We investigate potential models that could explain why multiple proto-stellar systems predominantly show single jets. During their formation, stars most frequently produce energetic outflows and jets. However, binary jets have only been observed in a very small number of systems. We model numerically 3D binary jets for various outflow parameters. We also model the propagation of jets from a specific source, namely L1551 IRS 5, known to have two jets, using recent observations as constraints for simulations with a new MHD code. We examine their morphology and dynamics, and produce synthetic emission maps. We find that the two jets interfere up to the stage where one of them is almost destroyed or engulfed into the second one. We are able to reproduce some of the observational features of L1551 such as the bending of the secondary jet. While the effects of orbital motion are negligible over the jets dynamical timeline, their interaction has significant impact on their morphology. If the jets are not strictly parallel, as in most observed cases, we show that the magnetic field can help the collimation and refocusing of both of the two jets.

  19. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    SciTech Connect (OSTI)

    Federrath, Christoph; Schober, Jennifer; Bovino, Stefano; Schleicher, Dominik R. G.

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ?/? = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ? 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub ?31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  20. Flow cytometer jet monitor system

    DOE Patents [OSTI]

    Van den Engh, Ger (Seattle, WA)

    1997-01-01

    A direct jet monitor illuminates the jet of a flow cytometer in a monitor wavelength band which is substantially separate from the substance wavelength band. When a laser is used to cause fluorescence of the substance, it may be appropriate to use an infrared source to illuminate the jet and thus optically monitor the conditions within the jet through a CCD camera or the like. This optical monitoring may be provided to some type of controller or feedback system which automatically changes either the horizontal location of the jet, the point at which droplet separation occurs, or some other condition within the jet in order to maintain optimum conditions. The direct jet monitor may be operated simultaneously with the substance property sensing and analysis system so that continuous monitoring may be achieved without interfering with the substance data gathering and may be configured so as to allow the front of the analysis or free fall area to be unobstructed during processing.

  1. Memory effects in turbulent transport

    E-Print Network [OSTI]

    Alexander Hubbard; Axel Brandenburg

    2009-11-13

    In the mean-field theory of magnetic fields, turbulent transport, i.e. the turbulent electromotive force, is described by a combination of the alpha effect and turbulent magnetic diffusion, which are usually assumed to be proportional respectively to the mean field and its spatial derivatives. For a passive scalar there is just turbulent diffusion, where the mean flux of concentration depends on the gradient of the mean concentration. However, these proportionalities are approximations that are valid only if the mean field or the mean concentration vary slowly in time. Examples are presented where turbulent transport possesses memory, i.e. where it depends crucially on the past history of the mean field. Such effects are captured by replacing turbulent transport coefficients with time integral kernels, resulting in transport coefficients that depend effectively on the frequency or the growth rate of the mean field itself. In this paper we perform numerical experiments to find the characteristic timescale (or memory length) of this effect as well as simple analytical models of the integral kernels in the case of passive scalar concentrations and kinematic dynamos. The integral kernels can then be used to find self-consistent growth or decay rates of the mean fields. In mean-field dynamos the growth rates and cycle periods based on steady state values of alpha effect and turbulent diffusivity can be quite different from the actual values.

  2. Compound cooling flow turbulator for turbine component

    DOE Patents [OSTI]

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

    2014-11-25

    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.

  3. The power spectrum of the circular noise

    E-Print Network [OSTI]

    Daniel Müller

    2005-09-30

    The circular noise is important in connection to Mach's principle, and also as a possible probe of the Unruh effect. In this letter the power spectrum of the detector following the Trocheries-Takeno motion in the Minkowski vacuum is analytically obtained in the form of an infinite series. A mean distribution function and corresponding energy density are obtained for this particular detected noise. The analogous of a non constant temperature distribution is obtained. And in the end, a brief discussion about the equilibrium configuration is given.

  4. Circular zig-zag scan video format

    DOE Patents [OSTI]

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

    1992-06-09

    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.

  5. A Family of Circular Bargmann Transforms

    E-Print Network [OSTI]

    Zouhair Mouayn

    2011-05-24

    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.

  6. Wave Decay in MHD Turbulence

    E-Print Network [OSTI]

    Andrey Beresnyak; Alex Lazarian

    2008-05-06

    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.

  7. BIPOLAR JETS LAUNCHED FROM ACCRETION DISKS. II. THE FORMATION OF ASYMMETRIC JETS AND COUNTER JETS

    SciTech Connect (OSTI)

    Fendt, Christian; Sheikhnezami, Somayeh E-mail: nezami@mpia.de

    2013-09-01

    We investigate the jet launching from accretion disks, in particular the formation of intrinsically asymmetric jet/counter jet systems. We perform axisymmetric MHD simulations of the disk-jet structure on a bipolar computational domain covering both hemispheres. We apply various models such as asymmetric disks with (initially) different scale heights in each hemisphere, symmetric disks into which a local disturbance is injected, and jets launched into an asymmetric disk corona. We consider both a standard global magnetic diffusivity distribution and a novel local diffusivity model. Typical disk evolution first shows substantial disk warping and then results in asymmetric outflows with a 10%-30% mass flux difference. We find that the magnetic diffusivity profile is essential for establishing a long-term outflow asymmetry. We conclude that bipolar asymmetry in protostellar and extragalactic jets can indeed be generated intrinsically and maintained over a long time by disk asymmetries and the standard jet launching mechanism.

  8. Unwinding of circular helicoidal molecules versus size

    E-Print Network [OSTI]

    Marco Zoli

    2015-04-12

    The thermodynamical stability of a set of circular double helical molecules is analyzed by path integral techniques. The minicircles differ only in \\textit{i)} the radius and \\textit{ii)} the number of base pairs ($N$) arranged along the molecule axis. Instead, the rise distance is kept constant. For any molecule size, the computational method simulates a broad ensemble of possible helicoidal configurations while the partition function is a sum over the path trajectories describing the base pair fluctuational states. The stablest helical repeat of every minicircle is determined by free energy minimization. We find that, for molecules with $N$ larger than $100$, the helical repeat grows linearly with the size and the twist number is constant. On the other hand, by reducing the size below $100$ base pairs, the double helices sharply unwind and the twist number drops to one for $N=\\,20$. This is predicted as the minimum size for the existence of helicoidal molecules in the closed form. The helix unwinding appears as a strategy to release the bending stress associated to the circularization of the molecules.

  9. Conversion of relativistic pair energy into radiation in the jets of active galactic nuclei

    E-Print Network [OSTI]

    R. Schlickeiser; R. Vainio; M. Boettcher; I. Lerche; M. Pohl; C. Schuster

    2002-07-02

    It is generally accepted that relativistic jet outflows power the nonthermal emission from active galactic nuclei (AGN). The composition of these jets -- leptonic versus hadronic -- is still under debate. We investigate the microphysical details of the conversion process of the kinetic energy in collimated relativistic pair outflows into radiation through interactions with the ambient interstellar medium. Viewed from the coordinate system comoving with the pair outflow, the interstellar protons and electrons represent a proton-electron beam propagating with relativistic speed in the pair plasma. We demonstrate that the beam excites both electrostatic and low-frequency magnetohydrodynamic Alfven-type waves via a two-stream instability in the pair background plasma, and we calculate the time evolution of the distribution functions of the beam particles and the generated plasma wave turbulence power spectra. For standard AGN jet outflow and environment parameters we show that the initial beam distributions of interstellar protons and electrons quickly relax to plateau-distributions in parallel momentum, transferring thereby one-half of the initial energy density of the beam particles to electric field fluctuations of the generated electrostatic turbulence. On considerably longer time scales, the plateaued interstellar electrons and protons will isotropise by their self-generated transverse turbulence and thus be picked-up in the outflow pair plasma. These longer time scales are also characteristic for the development of transverse hydromagnetic turbulence from the plateaued electrons and protons. This hydromagnetic turbulence upstream and downstream is crucial for diffusive shock acceleration to operate at external or internal shocks associated with pair outflows.

  10. Ram jet engine

    SciTech Connect (OSTI)

    Crispin, B.; Pohl, W.D.; Thomaier, D.; Voss, N.

    1983-11-29

    In a ram jet engine, a tubular combustion chamber is divided into a flame chamber followed by a mixing chamber. The ram air is supplied through intake diffusers located on the exterior of the combustion chamber. The intake diffusers supply combustion air directly into the flame chamber and secondary air is conveyed along the exterior of the combustion chambers and then supplied directly into the mixing chamber.

  11. Beam/Jet Trajectories April 1, 2009

    E-Print Network [OSTI]

    McDonald, Kirk

    Beam/Jet Trajectories April 1, 2009 #12;Hg Jet Target Geometry Solenoid Axis Hg Jet Proton Beam BEAM CROSS rJET Previous results: Radius 5mm, beam =67mrad crossing = 33mrad #12;Optimized Target Energy, GeV Optimized Target Radius #12;Beam Angle and Jet/Beam Crossing Angle 0 20 40 60 80 100 120 140

  12. JET Forward Programme & Opportunities for Collaboration

    E-Print Network [OSTI]

    JET Forward Programme & Opportunities for Collaboration Lorne Horton JET Exploitation Manager Contract for the Opera.on of the JET Facili.es Co-Funded by Euratom #12;L.D. Horton 2 FESAC Strategic Planning Panel 8 July 2014 - What makes JET unique! - Plans for JET exploitation

  13. Selected Items in Jet Algorithms

    E-Print Network [OSTI]

    Giuseppe Bozzi

    2008-08-06

    I provide a very brief overview of recent developments in jet algorithms, mostly focusing on the issue of infrared-safety.

  14. Photon + jets at D0

    E-Print Network [OSTI]

    Lars Sonnenschein

    2009-06-15

    Photon plus jet production has been studied by the D0 experiment in Run II of the Fermilab Tevatron Collider at a centre of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavour jet cross sections and double parton interactions in photon plus three jet events are presented. They are based on integrated luminosities between 0.4 fb$^-1 and 1.0 fb^-1. The results are compared to perturbative QCD calculations in various approximations.

  15. Turbulent AGN tori

    E-Print Network [OSTI]

    M. Schartmann; K. Meisenheimer; H. Klahr; M. Camenzind; S. Wolf; Th. Henning

    2008-08-05

    Recently, the MID-infrared Interferometric instrument (MIDI) at the VLTI has shown that dust tori in the two nearby Seyfert galaxies NGC 1068 and the Circinus galaxy are geometrically thick and can be well described by a thin, warm central disk, surrounded by a colder and fluffy torus component. By carrying out hydrodynamical simulations with the help of the TRAMP code (Klahr et al. 1999), we follow the evolution of a young nuclear star cluster in terms of discrete mass-loss and energy injection from stellar processes. This naturally leads to a filamentary large scale torus component, where cold gas is able to flow radially inwards. The filaments open out into a dense and very turbulent disk structure. In a post-processing step, we calculate observable quantities like spectral energy distributions or images with the help of the 3D radiative transfer code MC3D (Wolf 2003). Good agreement is found in comparisons with data due to the existence of almost dust-free lines of sight through the large scale component and the large column densities caused by the dense disk.

  16. Buoyant jet behavior in confined regions

    E-Print Network [OSTI]

    Fry, David J.

    1981-01-01

    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 ...

  17. Jet shapes with the broadening axis

    E-Print Network [OSTI]

    Larkoski, Andrew James

    Broadening is a classic jet observable that probes the transverse momentum structure of jets. Traditionally, broadening has been measured with respect to the thrust axis, which is aligned along the (hemisphere) jet momentum ...

  18. Miniconference on astrophysical jets P. M. Bellan

    E-Print Network [OSTI]

    Bellan, Paul M.

    Miniconference on astrophysical jets P. M. Bellan Applied Physics, California Institute 9 May 2005 This miniconference brought together observers of astrophysical jets, analytic and numerical modelers of both astrophysical jets and spheromaks, and laboratory experimentalists. The purpose

  19. JETS IN e+e- ANNIHILATION

    E-Print Network [OSTI]

    Cooper, Susan Catherine.

    2010-01-01

    io U s, Data Monte Carlo, ~zz Jet Model Monte Carlo, - Phaseener-jy for data (points), jet model (solid curve) and pnaotAXIS The quarKs and hence the jet axis should have the same

  20. On impinging near-field granular jets

    E-Print Network [OSTI]

    Arbelaez, D.; Zohdi, T. I.; Dornfeld, D. A.

    2009-01-01

    evolution models in abrasive jet micromachining. Wear 2008;SIMULATION OF GRANULAR JETS 26. Cheng X, Varas G, Citron D,behavior in a granular jet: emergence of a liquid with zero

  1. Searching for Jets in Heavy Ion Collisions

    E-Print Network [OSTI]

    Salur, Sevil

    2008-01-01

    measurements with full jet reconstruction in heavy ionDirect measurement of jets in s N N = 200 GeV Heavy Ion5–12, 2008 Searching for Jets in Heavy Ion Collisions Sevil

  2. Control of a high Reynolds number Mach 0.9 heated jet using plasma actuators

    SciTech Connect (OSTI)

    Kearney-Fischer, M.; Kim, J.-H.; Samimy, M.

    2009-09-15

    The results of particle image velocimetry (PIV) measurements in a high subsonic, heated, jet forced using localized arc filament plasma actuators (LAFPAs) show that LAFPAs can consistently produce significant mixing enhancement over a wide range of temperatures. These actuators have been used successfully in high Reynolds number, high-speed unheated jets. The facility consists of an axisymmetric jet with different nozzle blocks of exit diameter of 2.54 cm and variable jet temperature in an anechoic chamber. The focus of this paper is on a high subsonic (M{sub j}=0.9) jet. Twelve experiments with various forcing azimuthal modes (m=0, 1, and {+-}1) and temperatures (T{sub o}/T{sub a}=1.0, 1.4, and 2.0) at a fixed forcing Strouhal number (St{sub DF}=0.3) have been conducted and PIV results compared with the baseline results to characterize the effectiveness of LAFPAs for mixing enhancement. Centerline velocity and turbulent kinetic energy as well as jet width are used for determining the LAFPAs' effectiveness. The characteristics of large-scale structures are analyzed through the use of Galilean streamlines and swirling strength. Across the range of temperatures collected, the effectiveness of LAFPAs improves as temperature increases. Possible reasons for the increase in effectiveness are discussed.

  3. A Simple Algorithm for Detecting Circular Permutations in Proteins

    E-Print Network [OSTI]

    Amir, Amihood

    A Simple Algorithm for Detecting Circular Permutations in Proteins S. Uliel 1 , A. Fliess 1 , A CCR­96­10170 and BSF grant 96­000509. #12; Abstract Motivation: Circular permutation of a protein is a genetic operation in which part of the C­terminal of the protein is moved to its N­terminal. Recently

  4. Circular Planar Electrical Networks: Posets and Positivity Joshua Alman

    E-Print Network [OSTI]

    Ciocan-Fontanine, Ionut

    Circular Planar Electrical Networks: Posets and Positivity Joshua Alman , Carl Lian , and Brandon prove a host of new results on circular planar electrical networks. We first construct a poset EPn of electrical net- works with n boundary vertices, and prove that it is graded by number of edges of critical

  5. Expansion of a radial jet from a guillotine tube breach in a shell-and-tube heat exchanger

    SciTech Connect (OSTI)

    Velasco, F.J.S.; del Pra, C. Lopez; Herranz, Luis E. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Nuclear fission division, Nuclear Safety Research Unit, Avda. Complutense, 22, P.O. Box 28040 Madrid (Spain)

    2008-02-15

    Aerodynamics of a particle-laden gas jet entering the secondary side of a shell-and-tube heat exchanger from a tube guillotine breach, determines to a large extent radioactive retention in the break stage of the steam generator (SG) during hypothetical SGTR accident sequences in pressurized nuclear water reactors (PWRs). These scenarios were shown to be risk-dominant in PWRs. The major insights gained from a set of experiments into such aerodynamics are summarized in this paper. A scaled-down mock-up with representative dimensions of a real SG was built. Two-dimensional (2D) PIV technique was used to characterize the flow field in the space between the breach and the neighbor tubes in the gas flow range investigated (Re{sub D} = 0.8-2.7 x 10{sup 5}). Pitot tube measurements and CFD simulations were used to discuss and complement PIV data. The results, reported mainly in terms of velocity and turbulent intensity profiles, show that jet penetration and gas entrainment are considerably enhanced when increasing Re{sub D}. The presence of tubes was observed to distort the jet shape and to foster gas entrainment with respect to a jet expansion free of tubes. Turbulence intensity level close to the breach increases linearly with Re{sub D}. Account of this information into aerosol modeling will enhance predictive capability of inertial impaction and turbulent deposition equations. (author)

  6. Conversion of relativistic pair energy into radiation in the jets of active galactic nuclei

    E-Print Network [OSTI]

    Schlickeiser, R; Böttcher, M; Lerche, I; Pohl, M; Schuster, C

    2002-01-01

    It is generally accepted that relativistic jet outflows power the nonthermal emission from active galactic nuclei (AGN). The composition of these jets -- leptonic versus hadronic -- is still under debate. We investigate the microphysical details of the conversion process of the kinetic energy in collimated relativistic pair outflows into radiation through interactions with the ambient interstellar medium. Viewed from the coordinate system comoving with the pair outflow, the interstellar protons and electrons represent a proton-electron beam propagating with relativistic speed in the pair plasma. We demonstrate that the beam excites both electrostatic and low-frequency magnetohydrodynamic Alfven-type waves via a two-stream instability in the pair background plasma, and we calculate the time evolution of the distribution functions of the beam particles and the generated plasma wave turbulence power spectra. For standard AGN jet outflow and environment parameters we show that the initial beam distributions of in...

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

    E-Print Network [OSTI]

    Hayasaki, Kimitake; Loeb, Abraham

    2015-01-01

    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...

  8. Detection of circular polarization in light scattered from photosynthetic microbes

    E-Print Network [OSTI]

    Sparks, William B; Germer, Thomas A; Chen, Feng; DasSarma, Shiladitya; DasSarma, Priya; Robb, Frank T; Manset, Nadine; Kolokolova, Ludmilla; Reid, Neill; Macchetto, F Duccio; Martin, William; 10.1073/pnas.0810215106

    2009-01-01

    The identification of a universal biosignature that could be sensed remotely is critical to the prospects for success in the search for life elsewhere in the universe. A candidate universal biosignature is homochirality, which is likely to be a generic property of all biochemical life. Due to the optical activity of chiral molecules, it has been hypothesized that this unique characteristic may provide a suitable remote sensing probe using circular polarization spectroscopy. Here, we report the detection of circular polarization in light scattered by photosynthetic microbes. We show that the circular polarization appears to arise from circular dichroism of the strong electronic transitions of photosynthetic absorption bands. We conclude that circular polarization spectroscopy could provide a powerful remote sensing technique for generic life searches.

  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 the effect of turbulence fluctuations on surface heating rate by conducting direct numerical simulations (DNS subtle influence on the mean heating rate. We also find that the effect of turbulence

  10. 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 reaction. The influence of chemical reactions on temperature fluctuation variance, Reynolds stresses that the recombination reaction enhances turbulence, while the dissociation reaction damps turbulence. Chemical reactions

  11. Top Jets at the LHC

    E-Print Network [OSTI]

    Almeida, L.G.

    2009-01-01

    Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladSB-08-37; WIS/17/08-SEPT-DPP Top Jets at the LHC Leandro G.p T hadronically-decaying top quarks at the Large Hadron

  12. OPENING ANGLES OF COLLAPSAR JETS

    SciTech Connect (OSTI)

    Mizuta, Akira; Ioka, Kunihito

    2013-11-10

    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.

  13. 3 - 4 Turbulent combustion Princeton.key

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

    speed (s T ) Turbulent RMS velocity in the fresh gas (u') Low turbulence zone s T a u' Bending zone Quenching l i m i t s L 0 Problem: these functions are configuration...

  14. Active skin for turbulent drag reduction 

    E-Print Network [OSTI]

    Mani, Raghavendran

    2002-01-01

    capitalizes on recent advances in active turbulent drag reduction and active material based actuation to develop an active or "smart" skin for turbulent drag reduction in realistic flight conditions. The skin operation principle is based on computational...

  15. Diffusive Radiation in One-dimensional Langmuir Turbulence

    E-Print Network [OSTI]

    Fleishman, Gregory D

    2007-01-01

    We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. %at $\\omega=2\\omega\\pe \\gamma^2$. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets.

  16. Diffusive Radiation in One-dimensional Langmuir Turbulence

    E-Print Network [OSTI]

    Gregory D. Fleishman; Igor N. Toptygin

    2007-05-21

    We calculate spectra of radiation produced by a relativistic particle in the presence of one-dimensional Langmuir turbulence which might be generated by a streaming instability in the plasma, in particular, in the shock front or at the shock-shock interactions. The shape of the radiation spectra is shown to depend sensitively on the angle between the particle velocity and electric field direction. The radiation spectrum in the case of exactly transverse particle motion is degenerate and similar to that of spatially uniform Langmuir oscillations. In case of oblique propagation, the spectrum is more complex, it consists of a number of power-law regions and may contain a distinct high-frequency spectral peak. %at $\\omega=2\\omega\\pe \\gamma^2$. The emission process considered is relevant to various laboratory plasma settings and for astrophysical objects as gamma-ray bursts and collimated jets.

  17. 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

  18. Turbulence Induced Transport in Tokamaks

    SciTech Connect (OSTI)

    Caldas, I. L.; Marcus, F. A.; Heller, M. V. A. P.; Guimaraes-Filho, Z. O. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Batista, A. M. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, Ponta Grossa, PR (Brazil); Viana, R. L.; Lopes, S. R. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, PR (Brazil); Morrison, P. J.; Horton, W. [Department of Physics, University of Texas at Austin, Austin, Texas, 78712 (United States); Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas, 78712 (United States)

    2006-12-04

    This report is concerned with plasma edge turbulence and its relation to anomalous particle transport in tokamaks. First, experimental evidence of turbulence driven particle transport and measurements of the gradients of the equilibrium profiles in the Brazilian tokamaks TBR and TCABR are presented. Next, diffusion in a two drift-wave system is discussed. In this nonintegrable system, particle transport is associated with the onset of chaotic orbits. Finally, numerical evidence suggesting that a nonlinear three-mode interaction could contribute to the intermittent plasma fluctuations observed in tokamaks is presented.

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

    SciTech Connect (OSTI)

    McKinney, Jonathan C.; Uzdensky, Dmitri A.

    2012-03-14

    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.

  20. Gravitational Collapse in Turbulent Molecular Clouds. II. Magnetohydrodynamical Turbulence

    E-Print Network [OSTI]

    F. Heitsch; M. -M. Mac Low; R. S. Klessen

    2000-09-14

    Hydrodynamic supersonic turbulence can only prevent local gravitational collapse if the turbulence is driven on scales smaller than the local Jeans lengths in the densest regions, a very severe requirement (Paper I). Magnetic fields have been suggested to support molecular clouds either magnetostatically or via magnetohydrodynamic (MHD) waves. Whereas the first mechanism would form sheet-like clouds, the second mechanism not only could exert a pressure onto the gas counteracting the gravitational forces, but could lead to a transfer of turbulent kinetic energy down to smaller spatial scales via MHD wave interactions. This turbulent magnetic cascade might provide sufficient energy at small scales to halt local collapse. We test this hypothesis with MHD simulations at resolutions up to 256^3 zones, done with ZEUS-3D. We first derive a resolution criterion for self-gravitating, magnetized gas: in order to prevent collapse of magnetostatically supported regions due to numerical diffusion, the minimum Jeans length must be resolved by four zones. Resolution of MHD waves increases this requirement to roughly six zones. We then find that magnetic fields cannot prevent local collapse unless they provide magnetostatic support. Weaker magnetic fields do somewhat delay collapse and cause it to occur more uniformly across the supported region in comparison to the hydrodynamical case. However, they still cannot prevent local collapse for much longer than a global free-fall time.

  1. Turbulent mixing layers in supersonic protostellar outflows, with application to DG Tauri

    E-Print Network [OSTI]

    White, Marc C; Sutherland, Ralph S; Salmeron, Raquel; McGregor, Peter J

    2015-01-01

    Turbulent entrainment processes may play an important role in the outflows from young stellar objects at all stages of their evolution. In particular, lateral entrainment of ambient material by high-velocity, well-collimated protostellar jets may be the cause of the multiple emission-line velocity components observed in the microjet-scale outflows driven by classical T Tauri stars. Intermediate-velocity outflow components may be emitted by a turbulent, shock- excited mixing layer along the boundaries of the jet. We present a formalism for describing such a mixing layer based on Reynolds decomposition of quantities measuring fundamental properties of the gas. In this model, the molecular wind from large disc radii provides a continual supply of material for entrainment. We calculate the total stress profile in the mixing layer, which allows us to estimate the dissipation of turbulent energy, and hence the luminosity of the layer. We utilize MAPPINGS IV shock models to determine the fraction of total emission t...

  2. A spintronic source of circularly polarized single photons

    E-Print Network [OSTI]

    Pablo Asshoff; Andreas Merz; Heinz Kalt; Michael Hetterich

    2011-03-06

    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.

  3. A spintronic source of circularly polarized single photons

    E-Print Network [OSTI]

    Asshoff, Pablo; Kalt, Heinz; Hetterich, Michael

    2011-01-01

    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.

  4. A comparison between synthetic jets and continuous jets B.L. Smith, G.W. Swift

    E-Print Network [OSTI]

    Smith, Barton L.

    A comparison between synthetic jets and continuous jets B.L. Smith, G.W. Swift Abstract Experimental measurements and flow visualiza- tion of synthetic jets and continuous jets with matched Reynolds numbers are described. Although they have the same profile shape, synthetic jets are wider and slower than

  5. The interaction between two radial jets 

    E-Print Network [OSTI]

    Gruber, Thomas Clifton

    1993-01-01

    Arrays of impinging jets are used in industry for heat and mass transfer processes. A new type of jet was recently developed which could be utilized in such arrays. This jet is the radial jet and it offers the advantages of variable net force...

  6. Latest Jets Results from the Tevatron

    E-Print Network [OSTI]

    Christina Mesropian

    2011-06-15

    A comprehensive overview of the latest aspects of jet physics in proton-antiproton collisions at $\\sqrt{s}=$1.96 TeV is presented. In particular, measurements of the inclusive jet production, dijet and multi-jet production, and jet substructure studies are discussed.

  7. Jet energy calibration at the LHC

    E-Print Network [OSTI]

    Ariel Schwartzman

    2015-09-17

    Jets are one of the most prominent physics signatures of high energy proton proton (p-p) collisions at the Large Hadron Collider (LHC). They are key physics objects for precision measurements and searches for new phenomena. This review provides an overview of the reconstruction and calibration of jets at the LHC during its first Run. ATLAS and CMS developed different approaches for the reconstruction of jets, but use similar methods for the energy calibration. ATLAS reconstructs jets utilizing input signals from their calorimeters and use charged particle tracks to refine their energy measurement and suppress the effects of multiple p-p interactions (pileup). CMS, instead, combines calorimeter and tracking information to build jets from particle flow objects. Jets are calibrated using Monte Carlo (MC) simulations and a residual in situ calibration derived from collision data is applied to correct for the differences in jet response between data and Monte Carlo. Large samples of dijet, Z+jets, and photon+jet events at the LHC allowed the calibration of jets with high precision, leading to very small systematic uncertainties. Both ATLAS and CMS achieved a jet energy calibration uncertainty of about 1% in the central detector region and for jets with transverse momentum pT>100 GeV. At low jet pT, the jet energy calibration uncertainty is less than 4%, with dominant contributions from pileup, differences in energy scale between quark and gluon jets, and jet flavor composition.

  8. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, E.P. Jr.

    1999-01-12

    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 there between. 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. 2 figs.

  9. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, S.P.

    1999-03-02

    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.

  10. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, Steve P. (Livermore, CA)

    1999-03-02

    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.

  11. Water cooled steam jet

    DOE Patents [OSTI]

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

    1999-01-01

    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.

  12. Clustering instability in a freely falling granular jet

    E-Print Network [OSTI]

    Matthias E. Möbius

    2006-04-03

    This paper investigates a clustering instability of a freely falling granular jet composed of 100 micron glass spheres. The granular flow out of a circular nozzle starts out spatially uniform and then, further downstream, breaks up into well defined clusters. The role of air is investigated in this phenomenon by changing the ambient air pressure down to 1/5000th atm. An optical method is used that measures inhomogeneities in the flow in order to quantify the growth of the clusters. Clustering is observed down to the lowest pressure and the presence of air leads to larger drops but does not initiate the drop formation. The analysis shows that the drop size is set by fluctuations on the order of the size of the particles at the nozzle.

  13. Jets and Jet-like correlations in STAR

    E-Print Network [OSTI]

    Alice Ohlson; for the STAR Collaboration

    2012-10-08

    The propagation and modification of hard-scattered partons in the QGP can be studied using various types of jet and jet-like correlation measurements. The STAR detector with its full azimuthal and large pseudorapidity acceptance, as well as its wide transverse momentum (pT) coverage, is well-suited for these measurements. At mid-rapidity, azimuthal correlations of charged hadrons with the axis of a reconstructed trigger jet are used to study the modification of jet shapes and associated hadron yields from p+p to Au+Au. Dihadron correlations with back-to-back high-pT hadron pairs are used to investigate dijets and fragmentation biases. STAR's increased particle identification capabilities due to the Time-Of-Flight detector are utilized to investigate the differences between jet-related and bulk-related particle production. Dihadron correlations with identified trigger particles provide experimental tests of simple recombination theories. The comprehensive set of STAR jet-quenching measurements can be used to further constrain theories of parton energy loss at RHIC.

  14. CDF/PHYS/JET/CDFR/6419 Version 1.0

    E-Print Network [OSTI]

    Galtieri, Lina

    CDF/PHYS/JET/CDFR/6419 Version 1.0 June 19, 2003 Systematic Uncertainties Associated with Jet. Schmitt Jet Corrections Group Abstract We present an estimate of the systematic uncertainties on the jet jets, as well as for raw jets are given. 1 Introduction In order to convert the jet E T measured

  15. Fragmentation inside an identified jet

    E-Print Network [OSTI]

    Procura, Massimiliano

    Using Soft?Collinear Effective Theory (SCET) we derive factorization formulae for semi?inclusive processes where a light hadron h fragments from a jet whose invariant mass is measured. Our analysis yields a novel “fragmenting ...

  16. Radial flow pulse jet mixer

    DOE Patents [OSTI]

    VanOsdol, John G.

    2013-06-25

    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.

  17. Jet production at hadron colliders

    E-Print Network [OSTI]

    Jouttenus, Teppo T. (Teppo Tapani)

    2012-01-01

    Hadronic jets feature in many final states of interest in modern collider experiments. They form a significant Standard Model background for many proposed new physics processes and also probe QCD interactions at several ...

  18. Fragmentation inside an identified jet

    SciTech Connect (OSTI)

    Procura, Massimiliano; Stewart, Iain W.

    2011-05-23

    Using Soft-Collinear Effective Theory (SCET) we derive factorization formulae for semi-inclusive processes where a light hadron h fragments from a jet whose invariant mass is measured. Our analysis yields a novel 'fragmenting jet function' G{sub i}{sup h}(s,z) that depends on the jet invariant mass {radical}(s), and on the fraction z of the large light-cone momentum components of the hadron and the parent parton i. We show that G{sub i}{sup h}(s,z) can be computed in terms of perturbatively calculable coefficients, J{sub ij}(s,z/x), integrated against standard non-perturbative fragmentation functions, D{sub j}{sup h}(x). Our analysis yields a simple replacement rule that allows any factorization theorem depending on a jet function J{sub i} to be converted to a semi-inclusive process with a fragmenting hadron h.

  19. Aeroacoustics of volcanic jets: Acoustic power estimation and jet velocity dependence

    E-Print Network [OSTI]

    Matoza, Robin S; Fee, D; Neilsen, Tracianne B; Gee, Kent L; Ogden, Darcy E

    2013-01-01

    of noise from a military jet aircraft during ground run-up,Radiated by Subsonic Air Jets, David W. Taylor Model Basin,analysis of model-scale jet noise, J. Acoust. Soc. Am. ,

  20. Aeroacoustics of volcanic jets: Acoustic power estimation and jet velocity dependence

    E-Print Network [OSTI]

    Matoza, Robin S; Fee, D; Neilsen, Tracianne B; Gee, Kent L; Ogden, Darcy E

    2013-01-01

    e.g. , the exhaust from jet engines and rockets) [Kundu andow) issuing out of the jet engine or rocket. Other sourcesSupersonic jet noise characteristics and propagation: Engine

  1. Jet Quenching with Parton evolution

    E-Print Network [OSTI]

    Luan Cheng; Enke Wang

    2009-10-08

    We report the evolution effects on jet energy loss with detailed balance. The initial conditions and parton evolution based on perturbative QCD in the chemical non-equilibrated medium and Bjorken expanding medium at RHIC are determined. The parton evolution affect the jet energy loss evidently. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high P_{T} hadron spectra.

  2. Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence

    E-Print Network [OSTI]

    Kuznetsov, E A

    2015-01-01

    Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separa...

  3. Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence

    E-Print Network [OSTI]

    E. A. Kuznetsov; E. V. Sereshchenko

    2015-10-30

    Statistical characteristics of the Kraichnan direct cascade for two-dimensional hydrodynamic turbulence are numerically studied (with spatial resolution $8192\\times 8192$) in the presence of pumping and viscous-like damping. It is shown that quasi-shocks of vorticity and their Fourier partnerships in the form of jets introduce an essential influence in turbulence leading to strong angular dependencies for correlation functions. The energy distribution as a function of modulus $k$ for each angle in the inertial interval has the Kraichnan behavior, $\\sim k^{-4}$, and simultaneously a strong dependence on angles. However, angle average provides with a high accuracy the Kraichnan turbulence spectrum $E_k=C_K\\eta^{2/3} k^{-3}$ where $\\eta$ is enstrophy flux and the Kraichnan constant $C_K\\simeq 1.3$, in correspondence with the previous simulations. Familiar situation takes place for third-order velocity structure function $S_3^L$ which, as for the isotropic turbulence, gives the same scaling with respect to separation length $R$ and $\\eta$, $S_3^L=C_3\\eta R^3$, but the mean over angles and time $\\bar {C_3}$ differs from its isotropic value.

  4. Highly turbulent counterflow flames: A laboratory scale benchmark for practical systems

    SciTech Connect (OSTI)

    Coppola, Gianfilippo; Coriton, Bruno; Gomez, Alessandro

    2009-09-15

    We propose a highly turbulent counterflow flame as a very useful benchmark of complexity intermediate between laminar flames and practical systems. By operating in a turbulent Reynolds number regime of relevance to practical systems such as gas turbines and internal combustion engines, it retains the interaction of turbulence and chemistry of such environments, but offers several advantages including: (a) the achievement of high Reynolds numbers without pilot flames, which is particularly advantageous from a modeling standpoint; (b) control of the transition from stable flames to local extinction/reignition conditions; (c) compactness of the domain by comparison with jet flames, with obvious advantages from both a diagnostic and, especially, a computational viewpoint; and (d) the reduction or, altogether, elimination of soot formation, thanks to the high strain rates and low residence times of such a system, and the establishment of conditions of large stoichiometric mixture fraction, as required for robust flame stabilization. We demonstrate the phenomenology of such highly strained turbulent flames under conditions spanning unpremixed, partially premixed and premixed regimes. The system lends itself to the validation of DNS and other computational models. It is also well-suited for the examination of practical fuel blends - a need that is becoming more and more pressing in view of the anticipated diversification of the future fossil fuel supply. (author)

  5. Convectively generated zonal jets by thunderstorms on Jupiter

    E-Print Network [OSTI]

    Zhang, Xi Arthur; Showman, Adam

    2011-01-01

    formation of equatorial jets in freely decaying shallowof moist convection with zonal jets on Jupiter and Saturn,Generation of equatorial jets by large-scale latent heating

  6. Numerical simulations of volcanic jets: Importance of vent overpressure

    E-Print Network [OSTI]

    Ogden, Darcy E.; Wohletz, Kenneth H.; Glatzmaier, Gary A.; Brodsky, Emily E.

    2008-01-01

    Laboratory studies of volcanic jets, J. Geophys. Res. , 89(Analysis of supersonic air jets, Phys. Rev. , 76(5), 662 –and dynamics of supersonic jets, Astron. Astrophys. , 113(

  7. JETS OF NUCLEAR MATTER FROM HIGH ENERGY HEAVY ION COLLISIONS

    E-Print Network [OSTI]

    Stocker, H.

    2013-01-01

    of California. LBL-11774 Jets of Nuclear Matter from Highclusters. Strongly correlated jets of nuclear matter areExperimental analysis of the jet phenomena is in progress.

  8. PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS (Journal...

    Office of Scientific and Technical Information (OSTI)

    PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS Citation Details In-Document Search Title: PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS A protostellar jet and outflow...

  9. Coupled Mesoscale-Large-Eddy Modeling of Realistic Stable Boundary Layer Turbulence

    E-Print Network [OSTI]

    Wang, Yao; Manuel, Lance

    2013-01-01

    Site-specific flow and turbulence information are needed for various practical applications, ranging from aerodynamic/aeroelastic modeling for wind turbine design to optical diffraction calculations. Even though highly desirable, collecting on-site meteorological measurements can be an expensive, time-consuming, and sometimes a challenging task. In this work, we propose a coupled mesoscale-large-eddy modeling framework to synthetically generate site-specific flow and turbulence data. The workhorses behind our framework are a state-of-the-art, open-source atmospheric model called the Weather Research and Forecasting (WRF) model and a tuning-free large-eddy simulation (LES) model. Using this coupled framework, we simulate a nighttime stable boundary layer (SBL) case from the well-known CASES-99 field campaign. One of the unique aspects of this work is the usage of a diverse range of observations for characterization and validation. The coupled models reproduce certain characteristics of observed low-level jets....

  10. Stopping Cooling Flows with Jets

    E-Print Network [OSTI]

    Fabrizio Brighenti; William G. Mathews

    2006-01-24

    We describe 2D gasdynamical models of jets that carry mass as well as energy to the hot gas in galaxy clusters. These flows have many attractive attributes for solving the galaxy cluster cooling flow problem: Why the hot gas temperature and density profiles resemble cooling flows but show no spectral evidence of cooling to low temperatures. Using an approximate model for the cluster A1795, we show that mass-carrying jets can reduce the overall cooling rate to or below the low values implied by X-ray spectra. Biconical subrelativistic jets, described with several ad hoc parameters, are assumed to be activated when gas flows toward or cools near a central supermassive black hole. As the jets proceed out from the center they entrain more and more ambient gas. The jets lose internal pressure by expansion and are compressed by the ambient cluster gas, becoming rather difficult to observe. For a wide variety of initial jet parameters and several feedback scenarios the global cooling can be suppressed for many Gyrs while maintaining cluster temperature profiles similar to those observed. The intermittancy of the feedback generates multiple generations of X-ray cavities similar to those observed in the Perseus Cluster and elsewhere.

  11. Numerical Simulations of Bouncing Jets

    E-Print Network [OSTI]

    Bonito, Andrea; Lee, Sanghyun

    2015-01-01

    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. AN X-RAY VIEW OF THE JET CYCLE IN THE RADIO-LOUD AGN 3C120

    SciTech Connect (OSTI)

    Lohfink, Anne M.; Reynolds, Christopher S.; Mushotzky, Richard F.; Tombesi, Francesco; Jorstad, Svetlana G.; Marscher, Alan P.; Miller, Eric D.; Nowak, Michael A.; Aller, Hugh; Aller, Margo F.; Miller, Jon M.; Brenneman, Laura W.; Fabian, Andrew C.

    2013-08-01

    We present a study of the central engine in the broad-line radio galaxy 3C120 using a multi-epoch analysis of a deep XMM-Newton observation and two deep Suzaku pointings (in 2012). In order to place our spectral data into the context of the disk-disruption/jet-ejection cycles displayed by this object, we monitor the source in the UV/X-ray bands, and in the radio band. We find three statistically acceptable spectral models: a disk-reflection model, a jet model, and a jet+disk model. Despite being good descriptions of the data, the disk-reflection model violates the radio constraints on the inclination, and the jet model has a fine-tuning problem, requiring a jet contribution exceeding that expected. Thus, we argue for a composite jet+disk model. Within the context of this model, we verify the basic predictions of the jet-cycle paradigm, finding a truncated/refilling disk during the Suzaku observations and a complete disk extending down to the innermost stable circular orbit during the XMM-Newton observation. The idea of a refilling disk is further supported by the detection of the ejection of a new jet knot approximately one month after the Suzaku pointings. We also discover a step-like event in one of the Suzaku pointings in which the soft band lags the hard band. We suggest that we are witnessing the propagation of a disturbance from the disk into the jet on a timescale set by the magnetic field.

  13. Piloted methane/air jet flames : transport effects and aspects of scalar structure.

    SciTech Connect (OSTI)

    Karpetis, Adionos N. (Texas A& M University, College Station, TX); Chen, J. Y. (University of California, Berkeley, CA); Barlow, Robert S.; Frank, Jonathan H.

    2005-02-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  14. Piloted methane/air jet flames: Transport effects and aspects of scalar structure

    SciTech Connect (OSTI)

    Barlow, R.S.; Frank, J.H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States); Karpetis, A.N. [Department of Aerospace Engineering, Texas A and M University, College Station, TX 778453-3141 (United States); Chen, J.-Y. [Mechanical Engineering Department, University of California, Berkeley, CA 94720 (United States)

    2005-12-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  15. Turbulent equipartitions in two dimensional drift convection

    SciTech Connect (OSTI)

    Isichenko, M.B.; Yankov, V.V.

    1995-07-25

    Unlike the thermodynamic equipartition of energy in conservative systems, turbulent equipartitions (TEP) describe strongly non-equilibrium systems such as turbulent plasmas. In turbulent systems, energy is no longer a good invariant, but one can utilize the conservation of other quantities, such as adiabatic invariants, frozen-in magnetic flux, entropy, or combination thereof, in order to derive new, turbulent quasi-equilibria. These TEP equilibria assume various forms, but in general they sustain spatially inhomogeneous distributions of the usual thermodynamic quantities such as density or temperature. This mechanism explains the effects of particle and energy pinch in tokamaks. The analysis of the relaxed states caused by turbulent mixing is based on the existence of Lagrangian invariants (quantities constant along fluid-particle or other orbits). A turbulent equipartition corresponds to the spatially uniform distribution of relevant Lagrangian invariants. The existence of such turbulent equilibria is demonstrated in the simple model of two dimensional electrostatically turbulent plasma in an inhomogeneous magnetic field. The turbulence is prescribed, and the turbulent transport is assumed to be much stronger than the classical collisional transport. The simplicity of the model makes it possible to derive the equations describing the relaxation to the TEP state in several limits.

  16. Active control for turbulent premixed flame simulations

    SciTech Connect (OSTI)

    Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Lijewski, Michael J.

    2004-03-26

    Many turbulent premixed flames of practical interest are statistically stationary. They occur in combustors that have anchoring mechanisms to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. As a result, typical detailed simulations are performed in simplified model configurations such as decaying isotropic turbulence or inflowing turbulence. In these configurations, the turbulence seen by the flame either decays or, in the latter case, increases as the flame accelerates toward the turbulent inflow. This limits the duration of the eddy evolutions experienced by the flame at a given level of turbulent intensity, so that statistically valid observations cannot be made. In this paper, we apply a feedback control to computationally stabilize an otherwise unstable turbulent premixed flame in two dimensions. For the simulations, we specify turbulent in flow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm. We use the simulations to study the propagation and the local chemical variability of turbulent flame chemistry.

  17. POLICY FLASH 2015-32- Federal Acquisition Circular (FAC) 2005-83

    Broader source: Energy.gov [DOE]

    Federal Acquisition Circular (FAC) 2005-83 - brief summary of Federal Acquisition Regulation (FAR) amendments.

  18. 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)

    1985-01-15

    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.

  19. Resolving the jet in Cygnus A

    E-Print Network [OSTI]

    U. Bach; T. P. Krichbaum; E. Middelberg; W. Alef; J. A. Zensus

    2008-12-09

    Our previous studies revealed a good kinematic model for the jet of Cygnus A, but the counter-jet speed is still not well constrained. The central engine and part of the counter-jet of Cyg A are likely to be obscured by free-free absorbing material, presumably a thick torus. At mm-wavelengths, the absorber becomes optically thin, which provides a more detailed view into the inner nuclear region. Knowing the speed of jet and counter-jet and their flux density ratio allows to determine the jet Lorentz factors and orientation. Therefore we started to monitor Cyg A with global VLBI at 43GHz in Oct. 2007. Our first epoch reveals a previously unseen gap between both jets. This could be either a sign for a new counter-jet component that is slowly separating or we start to see the very inner acceleration region of the jet which is not efficiently radiating at radio wavelengths. Further more the image shows transversely resolved jet structures at distances beyond ~0.5pc which facilitate more detailed investigations addressing jet stratification. Analysis of the resolved jet structure shows that the initially wide jet (opening angle ~10deg) collimates within the first parsec into a edge-brightened jet with an opening angle of ~3deg.

  20. The First Calculation of Fractional Jets

    E-Print Network [OSTI]

    Daniele Bertolini; Jesse Thaler; Jonathan R. Walsh

    2015-05-14

    In collider physics, jet algorithms are a ubiquitous tool for clustering particles into discrete jet objects. Event shapes offer an alternative way to characterize jets, and one can define a jet multiplicity event shape, which can take on fractional values, using the framework of "jets without jets". In this paper, we perform the first analytic studies of fractional jet multiplicity $\\tilde{N}_{\\rm jet}$ in the context of $e^+e^-$ collisions. We use fixed-order QCD to understand the $\\tilde{N}_{\\rm jet}$ cross section at order $\\alpha_s^2$, and we introduce a candidate factorization theorem to capture certain higher-order effects. The resulting distributions have a hybrid jet algorithm/event shape behavior which agrees with parton shower Monte Carlo generators. The $\\tilde{N}_{\\rm jet}$ observable does not satisfy ordinary soft-collinear factorization, and the $\\tilde{N}_{\\rm jet}$ cross section exhibits a number of unique features, including the absence of collinear logarithms and the presence of soft logarithms that are purely non-global. Additionally, we find novel divergences connected to the energy sharing between emissions, which are reminiscent of rapidity divergences encountered in other applications. Given these interesting properties of fractional jet multiplicity, we advocate for future measurements and calculations of $\\tilde{N}_{\\rm jet}$ at hadron colliders like the LHC.

  1. An experimental study of the buckling behavior and frictional effects of a circular rod laterally constrained within a horizontal circular cylinder 

    E-Print Network [OSTI]

    Williams, Thomas H.

    1995-01-01

    This thesis is the result of an experimental study of the post buckling frictional effects of a circular rod laterally constrained within a horizontal circular cylinder. Previous theoretical works by Chen, Wu, and Cheatam ...

  2. Improved detection of atmospheric turbulence with SLODAR

    E-Print Network [OSTI]

    Michael Goodwin; Charles Jenkins; Andrew Lambert

    2007-06-19

    We discuss several improvements in the detection of atmospheric turbulence using SLOpe Detection And Ranging (SLODAR). Frequently, SLODAR observations have shown strong ground-layer turbulence, which is beneficial to adaptive optics. We show that current methods which neglect atmospheric propagation effects can underestimate the strength of high altitude turbulence by up to ~ 30%. We show that mirror and dome seeing turbulence can be a significant fraction of measured ground-layer turbulence, some cases up to ~ 50%. We also demonstrate a novel technique to improve the nominal height resolution, by a factor of 3, called Generalized SLODAR. This can be applied when sampling high-altitude turbulence, where the nominal height resolution is the poorest, or for resolving details in the important ground-layer.

  3. Jets in heavy ion collisions at RHIC

    E-Print Network [OSTI]

    Jan Kapitan

    2009-11-25

    Full jet reconstruction in heavy-ion collisions enables a complete study of the modification of jet structure due to energy loss in hot and dense QCD matter, but is challenging due to the high multiplicity environment. The STAR and PHENIX collaborations at RHIC have recently presented measurements of fully reconstructed jets from p+p, Cu+Cu and Au+Au collisions at $\\sqrt{s_\\mathrm{NN}} = 200 \\mathrm{GeV}$. We review the first results on inclusive jet spectra, di-jets and fragmentation functions and discuss their implications on understanding of jet quenching.

  4. Wave turbulence buildup in a vibrating plate

    E-Print Network [OSTI]

    Auliel, Maria Ines; Mordant, Nicolas

    2015-01-01

    We report experimental and numerical results on the buildup of the energy spectrum in wave turbulence of a vibrating thin elastic plate. Three steps are observed: first a short linear stage, then the turbulent spectrum is constructed by the propagation of a front in wave number space and finally a long time saturation due to the action of dissipation. The propagation of a front at the second step is compatible with scaling predictions from the Weak Turbulence Theory.

  5. Three-dimensional simulations of cellular non-premixed jet flames

    SciTech Connect (OSTI)

    Valaer, A.L.; Frouzakis, C.E.; Boulouchos, K.; Papas, P.; Tomboulides, A.G.

    2010-04-15

    The formation, dynamics and structure of cellular flames in circular non-premixed jets are examined with three-dimensional numerical simulations incorporating detailed descriptions of chemistry and transport. Similar to past experiments reported in the literature, CO{sub 2}-diluted hydrogen in diluted or pure oxygen co-flowing streams in the proximity of the extinction limit are considered. As in the experiments, several preferred cellular states are found to co-exist with the particular state realized depending on initial conditions as well as on the jet characteristics. The simulations provide additionally the temporal transitions to different stationary or rotating cellular flames, their detailed structure, and the dependence of the scaling of the realized number of cells with the vorticity thickness. (author)

  6. N Jettiness: An Inclusive Event Shape to Veto Jets

    E-Print Network [OSTI]

    Stewart, Iain

    Jet vetoes are essential in many analyses at the LHC and Tevatron. Typical signals have a specific number of hard jets or leptons, while backgrounds have additional jets. Vetoing undesired jets efficiently discriminates ...

  7. Flame Surface Fractal Characteristics in Premixed Turbulent Combustion at High Turbulence Intensities

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Flame Surface Fractal Characteristics in Premixed Turbulent Combustion at High Turbulence of the flame surfaces in premixed turbulent combustion, the fractal approach is considered to be one with diameters of 11.2 and 22.4 mm, with flames of propane­air with equivalence ratios of 0.8 and 1

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

    E-Print Network [OSTI]

    Tsvi Piran; Gilad Svirski; Julian Krolik; Roseanne M. Cheng; Hotaka Shiokawa

    2015-04-07

    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 ($\\sim 10^{51} (R/1000R_g)^{-1}$~erg). Recent numerical simulations \\citep{Shiokawa+2015} have revealed that the circularization scale is close to the scale of the most-bound initial orbits, $\\sim 10^3 M_{BH,6.5}^{-2/3} R_g \\sim 10^{15} M_{BH,6.5}^{1/3}$~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. The observed rise times, luminosities, temperatures, emission radii, and line widths seen in these TDEs \\citep[e.g.][]{Arcavi+2014} are all more readily explained in terms of heating associated with circularization than in terms of accretion.

  9. The Origin of Molecular Cloud Turbulence

    E-Print Network [OSTI]

    Padoan, Paolo; Haugboelle, Troels; Nordlund, Ake

    2015-01-01

    Turbulence is ubiquitous in molecular clouds (MCs), but its origin is still unclear because MCs are usually assumed to live longer than the turbulence dissipation time. It has been shown that interstellar medium (ISM) turbulence is likely driven by SN explosions, but it has never been demonstrated that SN explosions can establish and maintain a turbulent cascade inside MCs consistent with the observations. In this work, we carry out a simulation of SN-driven turbulence in a volume of (250 pc)^3, specifically designed to test if SN driving alone can be responsible for the observed turbulence inside MCs. We find that SN driving establishes velocity scaling consistent with the usual scaling laws of supersonic turbulence. This also means that previous idealized simulations of MC turbulence, driven with a random, large-scale volume force, were correctly adopted as appropriate models for MC turbulence, despite the artificial driving. We also find the same scaling laws extend to the interior of MCs, and their normal...

  10. Turbulent Supersonic Channel Flow: Direct Numerical Simulation and Modeling

    E-Print Network [OSTI]

    Heinz, Stefan

    modeling: the turbulence frequency production mechanism, wall damping effects on turbulence model frequency production mechanisms and wall damping effects may be explained very well on the basis, Chik w = wall viscosity = kinematic viscosity, = T = turbulent kinematic viscosity, Ck d = pressure

  11. Variation of bulk Lorentz factor in AGN jets due to Compton rocket in a complex photon field

    E-Print Network [OSTI]

    Vuillaume, Thomas; Petrucci, Pierre-Olivier

    2015-01-01

    Radio-loud active galactic nuclei are among the most powerful objects in the universe. In these objects, most of the emission comes from relativistic jets getting their power from the accretion of matter onto supermassive black holes. However, despite the number of studies, a jet's acceleration to relativistic speeds is still poorly understood. It is widely known that jets contain relativistic particles that emit radiation through several physical processes, one of them being the inverse Compton scattering of photons coming from external sources. In the case of a plasma composed of electrons and positrons continuously heated by the turbulence, inverse Compton scattering can lead to relativistic bulk motions through the Compton rocket effect. We investigate this process and compute the resulting bulk Lorentz factor in the complex photon field of an AGN composed of several external photon sources. We consider various sources here: the accretion disk, the dusty torus, and the broad line region. We take their geo...

  12. Search for Heavy Majorana Neutrinos in Same-Sign mumu+jets and ee+jets Events in pp Collisions at sqrt(s) = 7 GeV

    E-Print Network [OSTI]

    Giordano, Ferdinando

    2013-01-01

    4.4 Jet Reconstruction . . . . . . . . . . . . . . . . .5.2.5 Jet selection . . . . . .4.4.2 Anti-k T cone jet clustering algorithm . . . 4.4.3 Jet

  13. Jet energy scale setting with "photon+Jet" events at LHC energies. Event rates, Pt structure of jet

    E-Print Network [OSTI]

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

    2000-12-15

    In this paper the study of "photon+Jet" events is continued, aimed at jet energy scale setting and hadron calorimeter calibration at LHC energies. The event number distribution over Pt and pseudorapidity eta in the barrel region of the photon is presented. The features of "photon+Jet" events in CMS detector |eta|<1.4 are exposed. Pt structure of the region in the eta-phi space inside and beyond jet is also shown.

  14. Jets from Jets: Re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

    E-Print Network [OSTI]

    Benjamin Nachman; Pascal Nef; Ariel Schwartzman; Maximilian Swiatlowski; Chaowaroj Wanotayaroj

    2014-12-11

    Jets with a large radius $R\\gtrsim 1$ and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-$R$ jet configurations used by the LHC experiments is {\\it jet re-clustering}. Jet re-clustering introduces an intermediate scale $rjets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.

  15. Gravity waves from vortex dipoles and jets 

    E-Print Network [OSTI]

    Wang, Shuguang

    2009-05-15

    The dissertation first investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Several initially balanced and localized jets induced by vortex dipoles are examined here...

  16. Jet energy scale setting with "photon+Jet" events at LHC energies. Generalities, selection rules

    E-Print Network [OSTI]

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

    2000-12-14

    "photon+Jet" events, based on the q~q-> g+photon and qg-> q+photon subprocesses, are proposed for jet energy scale setting and hadron calorimeter calibration at LHC energies. General features and selection criteria of "photon+Jet" events that would provide a good photon Pt - jet Pt balance are described. CMS detector geometry is taken as the basement.

  17. ALMOST JET STRUCTURES AND FIRST JET-EXTENSIONS OF FIBRED MANIFOLDS

    E-Print Network [OSTI]

    Pasquero, Stefano

    ALMOST JET STRUCTURES AND FIRST JET-EXTENSIONS OF FIBRED MANIFOLDS Paola Morando Dipartimento di conditions for a manifold M to be diffeomorphic to the first jet­extension j1(N) of a fibred manifold N O are given in terms of almost jet structures, i.e. pairs (S, A), where S is a suitable type (2, 1) tensor

  18. Jets and Orography: Idealized Experiments with Tip-Jets and Lighthill Blocking

    E-Print Network [OSTI]

    Jets and Orography: Idealized Experiments with Tip-Jets and Lighthill Blocking P.B. Rhines issue on Jets 15 June 2006 #12;2 ABSTRACT In this note we describe some qualitative features of the generation of jet-like concentrated circulations, wakes and blocks by simple mountain-like orography, both

  19. Improved e-Jet Printing -TFOT Improved e-Jet Printing

    E-Print Network [OSTI]

    Rogers, John A.

    Improved e-Jet Printing - TFOT Home Sections News Articles Forums About Us Improved e-Jet Printing at the University of Illinois have developed a technology that provides higher resolution and more versatility in e-jet printing. As opposed to conventional ink-jet printers, where heat or mechanical vibrations are used

  20. M. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle

    E-Print Network [OSTI]

    Bahrami, Majid

    M. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle Gas-turbine engines. Aircraft gas turbines operate on an open cycle called jet-propulsion cycle. Some of the major differences between the gas-turbine and jet-propulsion cycles are: gases are expanded in the turbine to a pressure

  1. Experimental studies of unbiased gluon jets from e^+e^? annihilations using the jet boost algorithm

    E-Print Network [OSTI]

    Wilson, Graham Wallace; Abbiendi, G.; Ainsley, C.; Å kesson, P. F.; Alexander, G.; Allison, J.; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.

    2004-02-25

    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...

  2. Strategic Control of Transverse Jet Shear Layer Instabilities J. Davitian,

    E-Print Network [OSTI]

    M'Closkey, Robert T.

    engines, dilution jet injection in gas turbine combustors, thrust vectoring jets, and turbine blade filmStrategic Control of Transverse Jet Shear Layer Instabilities J. Davitian, C. Hendrickson, D jet in crossflow or transverse jet. Jet nozzles that are flush as well as elevated with respect

  3. ASCR Workshop on Turbulent Flow Simulations at the Exascale:...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ASCR Workshop on Turbulent Flow Simulations at the Exascale: Opportunities and Challenges ASCR Workshop on Turbulent Flow Simulations at the Exascale: Opportunities and Challenges...

  4. Turbulence-Flame Interactions in Type Ia Supernovae

    E-Print Network [OSTI]

    Aspden, Andrew J; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2 & 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5)

    2008-01-01

    dynamics of turbulent thermonuclear ?ames are essential tostudy of turbulent thermonuclear ? ames that explores aadapted to the study of thermonuclear ?ames, as described in

  5. Assessment of Combustion and Turbulence Models for the Simulation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Combustion and Turbulence Models for the Simulation of Combustion Processes in a DI Diesel Engine Assessment of Combustion and Turbulence Models for the Simulation of Combustion...

  6. Advanced thermally stable jet fuels

    SciTech Connect (OSTI)

    Schobert, H.H.

    1999-01-31

    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).

  7. Can we characterize turbulence in premixed flames?

    SciTech Connect (OSTI)

    Lipatnikov, A.N. [Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, 412 96 (Sweden)

    2009-06-15

    Modeling of premixed turbulent combustion involves averaging reaction rates in turbulent flows. The focus of most approaches to resolving this problem has been placed on determining the dependence of the mean rate w of product creation on the laminar flame speed S{sub L}, the rms turbulence velocity u', etc. The goal of the present work is to draw attention to another issue: May the input quantity u{sup '} for a model of w= w(u'/S{sub L},..) be considered to be known? The point is that heat release substantially affects turbulence and, hence, turbulence characteristics in premixed flames should be modeled. However, standard moment methods for numerically simulating turbulent flows do not allow us to evaluate the true turbulence characteristics in a flame. For instance, the Reynolds stresses in premixed flames are affected not only by turbulence itself, but also by velocity jump across flamelets. A common way to resolving this problem consists of considering the Reynolds stresses conditioned on unburned (or burned) mixture to be the true turbulence characteristics. In the present paper, this widely accepted but never proved hypothesis is put into question, first, by considering simple model constant-density problems (flame motion in an oscillating one-dimensional laminar flow; flame stabilized in a periodic shear, one-dimensional, laminar flow; turbulent mixing). In all the cases, the magnitude of velocity fluctuations, calculated using the conditioned Reynolds stresses, is affected by the intermittency of reactants and products and, hence, is not the true rms velocity. Second, the above claim is further supported by comparing balance equations for the mean and conditioned Reynolds stresses. The conditioned Reynolds stresses do not characterize the true turbulence in flames, because conditional averaging cuts off flow regions characterized by either high or low velocities. (author)

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

    SciTech Connect (OSTI)

    Singh, R.; Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 ; Jhang, Hogun; Diamond, P. H.; CMTFO and CASS, University of California, San Diego 92093-0424, California

    2013-11-15

    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.

  9. The Remote Photogrammetric Survey and Engineering Analysis of the Divertor Structure during JET’s Remote Tile Exchange

    E-Print Network [OSTI]

    The Remote Photogrammetric Survey and Engineering Analysis of the Divertor Structure during JET’s Remote Tile Exchange

  10. 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

  11. Jet physics at HERA, Tevatron and LHC

    E-Print Network [OSTI]

    C. Royon

    2008-11-10

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

  12. Jets in relativistic heavy ion collisions

    SciTech Connect (OSTI)

    Wang, Xin-Nian; Gyulassy, M.

    1990-09-01

    Several aspects of hard and semihard QCD jets in relativistic heavy ion collisions are discussed, including multiproduction of minijets and the interaction of a jet with dense nuclear matter. The reduction of jet quenching effect in deconfined phase of nuclear matter is speculated to provide a signature of the formation of quark gluon plasma. HIJING Monte Carlo program which can simulate events of jets production and quenching in heavy ion collisions is briefly described. 35 refs., 13 figs.

  13. Monte Carlo Tools for Jet Quenching

    E-Print Network [OSTI]

    Korinna Zapp

    2011-09-07

    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. Probing nuclear matter with jet conversions 

    E-Print Network [OSTI]

    Liu, W.; Fries, Rainer J.

    2008-01-01

    We discuss the flavor of leading jet partons as a valuable probe of nuclear matter. We point out that the coupling of jets to nuclear matter naturally leads to an alteration of jet chemistry even at high transverse momentum PT. In particular...

  15. JET PROPULSION WITHOUT INERTIA Saverio E. Spagnolie

    E-Print Network [OSTI]

    in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia://www.ima.umn.edu #12;Jet propulsion without inertia Saverio E. Spagnolie and Eric Lauga Department of MechanicalJET PROPULSION WITHOUT INERTIA By Saverio E. Spagnolie and Eric Lauga IMA Preprint Series # 2322

  16. Jet operators on fields Piotr Kowalski*

    E-Print Network [OSTI]

    Kowalski, Piotr

    Jet operators on fields Piotr Kowalski-Champaign Abstract We classify jet operators in the sense of Buium [Bu ] on a field of an arbitrary of the Frobenius map. 1 Introduction In [Bu ], Buium introduced jet operators on rings; they are natural

  17. Searching for Jets in Heavy Ion Collisions

    E-Print Network [OSTI]

    Sevil Salur

    2008-09-09

    Jet quenching measurements using leading particles and their correlations suffer from known biases, which can be removed via direct reconstruction of jets in central heavy ion collisions. In this talk, we discuss several modern jet reconstruction algorithms and background subtraction techniques that are appropriate to heavy ion collisions.

  18. Sandia Energy - Applied Turbulent Combustion

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II) byMultidayAlumni >ScientificApplied Turbulent Combustion Home

  19. Stochastic models for turbulent reacting flows

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

  20. Turbulence of a Unidirectional Flow Bjorn Birnir

    E-Print Network [OSTI]

    Birnir, Björn

    -flying aircraft. Turbulent drag also prevents the design of more fuel-efficient cars and aircrafts. Turbulence plays a role in the heat trans- fer in nuclear reactors, causes drag in oil pipelines and influence and intrigued people for centuries. Five centuries ago a fluid engineer by the name of Leonardo da Vinci tackled

  1. 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

  2. Star Formation Suppression Due to Jet Feedback in Radio Galaxies with Shocked Warm Molecular Gas

    E-Print Network [OSTI]

    Lanz, Lauranne; Alatalo, Katherine; Appleton, Philip N

    2015-01-01

    We present Herschel observations of 22 radio galaxies, selected for the presence of shocked, warm molecular hydrogen emission. We measured and modeled spectral energy distributions (SEDs) in 33 bands from the ultraviolet to the far-infrared to investigate the impact of jet feedback on star formation activity. These galaxies are massive, early-type galaxies with normal gas-to-dust ratios, covering a range of optical and IR colors. We find that the star formation rate (SFR) is suppressed by a factor of ~3-6, depending on how molecular gas mass is estimated. We suggest this suppression is due to the shocks driven by the radio jets injecting turbulence into the interstellar medium (ISM), which also powers the luminous warm H2 line emission. Approximately 25% of the sample shows suppression by more than a factor of 10. However, the degree of SFR suppression does not correlate with indicators of jet feedback including jet power, diffuse X-ray emission, or intensity of warm molecular H2 emission, suggesting that whi...

  3. Meso-scale turbulence in living fluids

    E-Print Network [OSTI]

    Wensink, Henricus H; Heidenreich, Sebastian; Drescher, Knut; Goldstein, Raymond E; Löwen, Hartmut; Yeomans, Julia M

    2012-01-01

    Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior amongst the simplest forms of life, and is important for fluid mixing and molecular transport on the microscale. The mathematical characterization of turbulence phenomena in active non-equilibrium fluids proves even more difficult than for conventional liquids or gases. It is not known which features of turbulent phases in living matter are universal or system-specific, or which generalizations of the Navier-Stokes equations are able to describe them adequately. Here, we combine experiments, particle simulations, and continuum theory to identify the statistical properties of self-sustained meso-scale turbulence in active systems. To study how dimensionality and boundary conditions affect collective bacterial dynamics, we measured energy spectra and structure functions in dense Bacillus subtilis su...

  4. Numerical simulations of strong incompressible magnetohydrodynamic turbulence

    SciTech Connect (OSTI)

    Mason, J.; Cattaneo, F.; Perez, J. C.; Boldyrev, S.

    2012-05-15

    Magnetised plasma turbulence pervades the universe and is likely to play an important role in a variety of astrophysical settings. Magnetohydrodynamics (MHD) provides the simplest theoretical framework in which phenomenological models for the turbulent dynamics can be built. Numerical simulations of MHD turbulence are widely used to guide and test the theoretical predictions; however, simulating MHD turbulence and accurately measuring its scaling properties is far from straightforward. Computational power limits the calculations to moderate Reynolds numbers and often simplifying assumptions are made in order that a wider range of scales can be accessed. After describing the theoretical predictions and the numerical approaches that are often employed in studying strong incompressible MHD turbulence, we present the findings of a series of high-resolution direct numerical simulations. We discuss the effects that insufficiencies in the computational approach can have on the solution and its physical interpretation.

  5. 3-D Interpretation of Sewer Circular Structures Marina Kolesnik,

    E-Print Network [OSTI]

    Kolesnik, Marina

    3-D Interpretation of Sewer Circular Structures Marina Kolesnik, Institute for Autonomous interpretation of images taken in a sewer by a robot-inspector is presented. Modern sewers made of concrete sections. These pipe ends and joints provide regular marks on the sewer images and can be used for their 3

  6. SEVENTEENTH ANNUAL CATALOG CIRCULAR FOR 1899-1900

    E-Print Network [OSTI]

    ........................................ Governor. Ex-Officio. THOMAS J. KIRK ............ Superintendent of Public Instruction. Ex-Officio. N. P. SMITH, Drawing and Sloyd. AGNES ELLIOTT, History. KINDERGARTEN TRAINING DEPARTMENT. FLORENCE LAWSON, Janitor of Gymnasium. THOMAS FARNHAM , Gardener. #12;6 STATE NORMAL SCHOOL CIRCULAR. The State Normal

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

    E-Print Network [OSTI]

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

    2015-01-01

    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...

  8. Radio Linear and Circular Polarization from M81*

    E-Print Network [OSTI]

    Andreas Brunthaler; Geoffrey C. Bower; Heino Falcke

    2006-05-05

    We present results from archival Very Large Array (VLA) data and new VLA observations to investigate the long term behavior of the circular polarization of M81*, the nuclear radio source in the nearby galaxy M81. We also used the Berkeley-Illinois-Maryland Association (BIMA) array to observe M81* at 86 and 230 GHz. M81* is unpolarized in the linear sense at a frequency as high as 86 GHz and shows variable circular polarization at a frequency as high as 15 GHz. The spectrum of the fractional circular polarization is inverted in most of our observations. The sign of circular polarization is constant over frequency and time. The absence of linear polarization sets a lower limit to the accretion rate of $10^{-7} M_\\odot y^{-1}$. The polarization properties are strikingly similar to the properties of Sgr A*, the central radio source in the Milky Way. This supports the hypothesis that M81* is a scaled up version of Sgr A*. On the other hand, the broad band total intensity spectrum declines towards milimeter wavelengths which differs from previous observations of M81* and also from Sgr A*.

  9. FORCE AND DISPLACEMENT INFLUENCE FUNCTIONS FOR THE CIRCULAR RING

    E-Print Network [OSTI]

    Barber, James R.

    of Mechanical Engineering, Universityof Newcastie upon Tyne.Member of the Institution A set of influence to the ring. In the design field, it is usual to build up the solution to such a problem by superposition. Lists of elementary solutions appropriate to the complete circular ring are given by Roark (l

  10. Cellular pattern formation in circular domains Antonio Palacios,a)

    E-Print Network [OSTI]

    Cellular pattern formation in circular domains Antonio Palacios,a) Gemunu H. Gunaratne 1997; accepted for publication 24 June 1997 An analysis of stationary and nonstationary cellular. Motivated by the observa- tion of novel stationary and nonstationary cellular states on a flame front, we

  11. The Particle Content of Extragalactic Jets

    E-Print Network [OSTI]

    David S. De Young

    2006-05-31

    Recent x-ray and radio data from radio sources in galaxy clusters are used to show that the pdV work required to inflate the radio lobes exceeds all other energy estimates deduced from the radio emission. If the required jet energy density has an isotropic pressure, then in almost all cases the jet cannot be confined by an external medium. This problem can be resolved with jets dominated by cold protons, but even here the accompanying energy density in relativistic electons can cause decollimation. Electron-positron jets cannot solve this problem unless they are highly beamed with unusual energy distributions. Poynting flux jets may be a viable alternative.

  12. 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

    2001-04-27

    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.

  13. The Structure and Dynamics of GRB Jets

    E-Print Network [OSTI]

    Jonathan Granot

    2006-10-12

    There are several lines of evidence which suggest that the relativistic outflows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true energy release and the event rate of GRBs, and can constrain the mechanism responsible for the acceleration and collimation of the jet. Nevertheless, the jet structure and its dynamics as it sweeps up the external medium and decelerates, are not well understood. In this review I discuss our current understanding of GRB jets, stressing their structure and dynamics.

  14. A comparison of experimental and numerical results on convective thermal mixing of three vertical, quasi-planar jets

    SciTech Connect (OSTI)

    Tokuhiro, A.T.; Kimura, N.; Nishimura, M.; Kobayashi, J.; Miyakoshi, H.

    1999-07-01

    The thermal-hydraulic mixing of three quasi-planar vertical water jets was experimentally and numerically investigated. The central jet was initially 5 C lower in temperature than the other two. The hydraulic diameter and average exit velocity-based Reynolds and Richardson numbers were, Re{sub D} = 2 x 10{sup 4}, Ri{sub D} = 0.002. Besides temperature measurements from a traversing array of 37 thermocouples, velocity measurements were made using laser and ultrasound Doppler velocimetries (LDV and UDV). In parallel the in-house code, CASCADE, featuring a {kappa}-{epsilon} turbulence model was used to simulate the experimental flow configuration. A comparison of the experimental and numerical results showed that code validation by LDV/UDV was possible and in particular that time-averaged field and frequency characteristics of transversely swaying jets, even under Reynolds averaging of the conservation equations, could be simulated. A representative comparison of the amplitude of oscillation is shown in Figure A-1 with an inset of the visualized flow and sample time-series of the temperature fluctuations at the position indicated. The difference in the predominant frequency, the numerically predicted {approximately}1.6 Hz versus the experimental {approximately}2.25 Hz, is attributed to the turbulence model that overestimate thus effective fluid viscosity. Development of an accurate numerical simulation is of relevance to the design of the liquid metal fast breeder reactor (LMFBR), where the lack of mixing of the cold sodium may initiate thermal striping; that is, poorly mixed hot and cold streams may thermally stress the components onto which they impinge. Turbulent mixing of jets is equally of general interest to environmental and material processing flows.

  15. Shear Layer Instabilities and Mixing in Variable Density Transverse Jet Flows

    E-Print Network [OSTI]

    Getsinger, Daniel

    2012-01-01

    of the Jet in Crossflow . . . . . . . . . . . . . . .The Variable Density Jet in Crossflow . . . . . . . . .The Single-Phase Jet in Crossflow . . . . . . .

  16. Jets and Underlying Events at LHC Energies

    E-Print Network [OSTI]

    A. G. Agócs; G. G. Barnaföldi; P. Lévai

    2010-11-24

    Jet-matter interaction remains a central question and a theoretical challenge in heavy-ion physics and might become important in high-multiplicity events in proton-proton collisions at LHC energies. Full jet measurement at LHC offer the proper tool to investigate energy loss process and fragmentation of hard parton in the medium. Since jet reconstruction will be constrained to small cone sizes, then study of the connection between jets and surrounding environment provides a further possibility to extend our exploration. We study jets at s = (14 TeV)^2 and pp collisions at s = (7 TeV)^2. We analyze the flavor components in jet-like environments. We introduce a definition for surrounding cones/belts and investigate flavor dependence and correlation of different hadron species produced in jets. Here, we focus on proton-triggered correlations. Our analysis can be extended for heavy ion collisions.

  17. The jets of the Vela pulsar

    E-Print Network [OSTI]

    O. Kargaltsev; G. G. Pavlov; M. A. Teter; D. Sanwal

    2003-06-09

    Chandra observations of the Vela pulsar-wind nebula (PWN) have revealed a jet in the direction of the pulsar's proper motion, and a counter-jet in the opposite direction, embedded in diffuse nebular emission. The jet consists of a bright, 8''-long inner jet, between the pulsar and the outer arc, and a dim, curved outer jet that extends up to 100'' in approximately the same direction. From the analysis of thirteen Chandra observations spread over about 2.5 years we found that this outer jet shows particularly strong variability, changing its shape and brightness. We observed bright blobs in the outer jet moving away from the pulsar with apparent speeds (0.3-0.6)c and fading on time-scales of days to weeks. The spectrum of the outer jet fits a power-law model with a photon index of 1.3\\pm0.1. The X-ray emission of the outer jet can be interpreted as synchrotron radiation of ultrarelativistic electrons/positrons. This interpretation allows one to estimate the magnetic field, ~100 microGauss, maximum energy of X-ray emitting electrons, ~2\\times 10^{14} eV, and energy injection rate, ~8\\times 10^{33} erg/s, for the outer jet. In the summed PWN image we see a dim, 2'-long outer counter-jet, which also shows a power-law spectrum with photon ined of 1.2-1.5. Southwest of the jet/counter-jet an extended region of diffuse emission is seen. Relativistic particles responsible for this radiation are apparently supplied by the outer jet.

  18. Jet Dipolarity: Top Tagging with Color Flow

    SciTech Connect (OSTI)

    Hook, Anson; Jankowiak, Martin; /SLAC /Stanford U., Phys. Dept.; Wacker, Jay G.; /SLAC

    2011-08-12

    A new jet observable, dipolarity, is introduced that can distinguish whether a pair of subjets arises from a color singlet source. This observable is incorporated into the HEPTopTagger and is shown to improve discrimination between top jets and QCD jets for moderate to high p{sub T}. The impressive resolution of the ATLAS and CMS detectors means that a typical QCD jet at the LHC deposits energy in {Omicron}(10-100) calorimeter cells. Such fine-grained calorimetry allows for jets to be studied in much greater detail than previously, with sophisticated versions of current techniques making it possible to measure more than just the bulk properties of jets (e.g. event jet multiplicities or jet masses). One goal of the LHC is to employ these techniques to extend the amount of information available from each jet, allowing for a broader probe of the properties of QCD. The past several years have seen significant progress in developing such jet substructure techniques. A number of general purpose tools have been developed, including: (i) top-tagging algorithms designed for use at both lower and higher p{sub T} as well as (ii) jet grooming techniques such as filtering, pruning, and trimming, which are designed to improve jet mass resolution. Jet substructure techniques have also been studied in the context of specific particle searches, where they have been shown to substantially extend the reach of traditional search techniques in a wide variety of scenarios, including for example boosted Higgses, neutral spin-one resonances, searches for supersymmetry, and many others. Despite these many successes, however, there is every reason to expect that there remains room for refinement of jet substructure techniques.

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

    SciTech Connect (OSTI)

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

    2006-12-01

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

  20. Turbulence

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

    to the major radius were measured using the recently upgraded phase-contrast imaging (PCI) diagnostic 4. The 32 vertical chords of the PCI system (see Fig. 1 (a)) enables the...

  1. Terascale direct numerical simulations of turbulent combustion using S3D

    SciTech Connect (OSTI)

    Chen, Jackie; Klasky, Scott A; Hawkes, Evatt R; Sankaran, Ramanan; Choudhary, Alok; Yoo, Chun S; Liao, Wei-keng; Podhorszki, Norbert

    2009-01-01

    Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization 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 computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory intensive loops in the code. Through the careful application of loop transformations, data reuse in cache is exploited thereby reducing memory bandwidth needs, and hence, improving S3D's nodal performance. To enhance collective parallel I/O in S3D, an MPI-I/O caching design is used to construct a two-stage write-behind method for improving the performance of write-only operations. The simulations generate tens of terabytes of data requiring analysis. Interactive exploration of the simulation data is enabled by multivariate time-varying volume visualization. The visualization highlights spatial and temporal correlations between multiple reactive scalar fields using an intuitive user interface based on parallel coordinates and time histogram. Finally, an automated combustion workflow is designed using Kepler to manage large-scale data movement, data morphing, and archival and to provide a graphical display of run-time diagnostics.

  2. Outflow Driven Turbulence in Molecular Clouds

    E-Print Network [OSTI]

    Jonathan J. Carroll; Adam Frank; Eric G. Blackman; Andrew J. Cunningham; Alice C. Quillen

    2008-05-30

    In this paper we explore the relationship between protostellar outflows and turbulence in molecular clouds. Using 3-D numerical simulations we focus on the hydrodynamics of multiple outflows interacting within a parsec scale volume. We explore the extent to which transient outflows injecting directed energy and momentum into a sub-volume of a molecular cloud can be converted into random turbulent motions. We show that turbulence can readily be sustained by these interactions and show that it is possible to broadly characterize an effective driving scale of the outflows. We compare the velocity spectrum obtained in our studies to that of isotropically forced hydrodynamic turbulence finding that in outflow driven turbulence a power law is indeed achieved. However we find a steeper spectrum (beta ~ 3) is obtained in outflow driven turbulence models than in isotropically forced simulations (beta ~ 2). We discuss possible physical mechanisms responsible for these results as well and their implications for turbulence in molecular clouds where outflows will act in concert with other processes such as gravitational collapse.

  3. The spatio-temporal spectrum of turbulent flows

    E-Print Network [OSTI]

    di Leoni, P Clark; Mininni, P D

    2015-01-01

    Identification and extraction of vortical structures and of waves in a disorganized flow is a mayor challegen in the study of turbulence. We present a study of the spatio-temporal behavior of turbulent flows in the presence of different restitutive forces. We show how to compute and analyze the spatio-temporal spectrum from data stemming from numerical simulations and from laboratory experiments. Four cases are considered: homogeneous and isotropic turbulence, rotating turbulence, stratified turbulence, and water wave turbulence. For homogeneous and isotropic turbulence, the spectrum allows identification of random sweeping. For rotating and for stratified turbulence, the spectrum allows identification of the waves, quantification of the energy in the waves and in the turbulent eddies, and identification of physical mechanisms such as Doppler shift and wave absorption in critical layers. Finally, in water wave turbulence the spectrum shows a transition from gravity-capillary waves to bound waves as the amplit...

  4. On the hierarchy of trinucleotide n-circular codes and their corresponding amino acids

    E-Print Network [OSTI]

    Michel, Christian

    properties. However, it is possible to encode all 20 amino acids using codes from the largest classOn the hierarchy of trinucleotide n-circular codes and their corresponding amino acids Elena Fimmel is developed. The maximal number of amino acids encoded by circular codes is investigated. The circularity

  5. Nonlinear Dynamics of Coiling in Viscoelastic Jets

    E-Print Network [OSTI]

    Trushant Majmudar; Matthieu Varagnat; William Hartt; Gareth McKinley

    2010-12-09

    Instabilities in free surface continuous jets of non-Newtonian fluids, although relevant for many industrial processes, remain less well understood in terms of fundamental fluid dynamics. Inviscid, and viscous Newtonian jets have been studied in great detail; buckling instability in viscous jets leads to regular periodic coiling of the jet that exhibits a non-trivial frequency dependence with the height of the fall. Very few experimental or theoretical studies exist for continuous viscoelastic jets beyond the onset of the first instability. Here, we present a systematic study of the effects of viscoelasticity on the dynamics of free surface continuous jets of surfactant solutions that form worm-like micelles. We observe complex nonlinear spatio-temporal dynamics of the jet and uncover a transition from periodic to doubly-periodic or quasi-periodic to a multi-frequency, possibly chaotic dynamics. Beyond this regime, the jet dynamics smoothly crosses over to exhibit the "leaping shampoo effect" or the Kaye effect. This enables us to view seemingly disparate jetting dynamics as one coherent picture of successive instabilities and transitions between them. We identify the relevant scaling variables as the dimensionless height, flow rate, and the elasto-gravity number and present a regime map of the dynamics of the jet in terms of these parameters.

  6. QCD resummation for light-particle jets

    E-Print Network [OSTI]

    Hsiang-nan Li; Zhao Li; C. -P. Yuan

    2013-04-08

    We construct an evolution equation for the invariant-mass distribution of light-quark and gluon jets in the framework of QCD resummation. The solution of the evolution equation exhibits a behavior consistent with Tevatron CDF data: the jet distribution vanishes in the small invariant-mass limit, and its peak moves toward the high invariant-mass region with the jet energy. We also construct an evolution equation for the energy profile of the light-quark and gluon jets in the similar framework. The solution shows that the energy accumulates faster within a light-quark jet cone than within a gluon jet cone. The jet energy profile convoluted with hard scattering and parton distribution functions matches well with the Tevatron CDF and the large-hadron-collider (LHC) CMS data. Moreover, comparison with the CDF and CMS data implies that jets with large (small) transverse momentum are mainly composed of the light-quark (gluon) jets. At last, we discuss the application of the above solutions for the light-particle jets to the identification of highly-boosted heavy particles produced at LHC.

  7. Advanced Thermally Stable Jet Fuels

    SciTech Connect (OSTI)

    A. Boehman; C. Song; H. H. Schobert; M. M. Coleman; P. G. Hatcher; S. Eser

    1998-01-01

    The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles 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; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  8. Fluid jet electric discharge source

    DOE Patents [OSTI]

    Bender, Howard A. (Ripon, CA)

    2006-04-25

    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.

  9. CDF/PHYS/JET/PUBLIC/7898 Page 1 of 12

    E-Print Network [OSTI]

    Field, Richard

    CDF/PHYS/JET/PUBLIC/7898 Page 1 of 12 Jet Physics and the Underlying Event at the Tevatron Rick, Florida, 32611, USA Abstract: Tevatron Run 2 results on the inclusive jet cross section (MidPoint and KT algorithm) and the b-jet and bb ­jet cross section (MidPoint algorithm) are presented and compared

  10. CDF/PUB/JET/PUBLIC/7728 Page 1 of 6

    E-Print Network [OSTI]

    Field, Richard

    CDF/PUB/JET/PUBLIC/7728 Page 1 of 6 JET PHYSICS IN RUN 2 AT CDF Rick Field1 (for the CDF Run 2 results on the inclusive jet cross section (KT algorithm) and the b-jet cross section (Mid the direction of the leading jet to isolate regions of - space that are very sensitive to the "beam

  11. In Situ Jet Energy Calibration In Atlas Based On

    E-Print Network [OSTI]

    Hupkes, Hermen Jan

    In Situ Jet Energy Calibration In Atlas Based On Z+Jet Events By Hermen Jan Hupkes 252 Ge; IN SITU JET ENERGY CALIBRATION IN ATLAS BASED ON Z+JET EVENTS Hermen Jan Hupkes Mathematisch Instituut #12; #12; Contents 1 Introduction 1 2 The Atlas Detector 7 3 Jet Measurements in Atlas 11 3

  12. In Situ Jet Energy Calibration In Atlas Based On

    E-Print Network [OSTI]

    Hupkes, Hermen Jan

    In Situ Jet Energy Calibration In Atlas Based On Z+Jet Events By Hermen Jan Hupkes 252 Ge SITU JET ENERGY CALIBRATION IN ATLAS BASED ON Z+JET EVENTS Hermen Jan Hupkes Mathematisch Instituut #12;#12;Contents 1 Introduction 1 2 The Atlas Detector 7 3 Jet Measurements in Atlas 11 3

  13. Inhomogeneous distribution of droplets in cloud turbulence

    E-Print Network [OSTI]

    Itzhak Fouxon; Yongnam Park; Roei Harduf; Changhoon Lee

    2014-10-30

    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.

  14. Equilibration of an atmosphere by geostrophic turbulence

    E-Print Network [OSTI]

    Jansen, Malte F. (Malte Friedrich)

    2013-01-01

    A major question for climate studies is to quantify the role of turbulent eddy fluxes in maintaining the observed atmospheric mean state. It has been argued that eddy fluxes keep the mid-latitude atmosphere in a state that ...

  15. Selected problems in turbulence theory and modeling 

    E-Print Network [OSTI]

    Jeong, Eun-Hwan

    2004-09-30

    pressure-strain correlation is investigated and constraining criteria for the rapid pressure-strain correlation models are developed. In the last topic, "unsteady computation of turbulent flow past a square cylinder using partially-averaged Navier...

  16. Aspects of wave turbulence in preheating

    SciTech Connect (OSTI)

    Crespo, José A.; De Oliveira, H.P., E-mail: jaacrespo@gmail.com, E-mail: oliveira@dft.if.uerj.br [Universidade do Estado do Rio de Janeiro, Instituto de Física - Departamento de Física Teórica, Rio de Janeiro, RJ, CEP 20550-013 Brazil. (Brazil)

    2014-06-01

    In this work we have studied the nonlinear preheating dynamics of several inflationary models. 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 the matter contents are fields instead of usual fluids. Turbulence develops due to the nonlinear interations of waves, here represented by the small inhomogeneities of the scalar fields. We present relevant aspects of wave turbulence such as the Kolmogorov-Zakharov spectrum in frequency and wave number that indicates the energy transfer through scales. From the power spectrum of the matter energy density we were able to estimate the temperature of the thermalized system.

  17. Laminated Wave Turbulence: Generic Algorithms I

    E-Print Network [OSTI]

    E. Kartashova; A. Kartashov

    2006-09-07

    The model of laminated wave turbulence presented recently unites both types of turbulent wave systems - statistical wave turbulence (introduced by Kolmogorov and brought to the present form by numerous works of Zakharov and his scientific school since nineteen sixties) and discrete wave turbulence (developed in the works of Kartashova in nineteen nineties). The main new feature described by this model is the following: discrete effects do appear not only in the long-wave part of the spectral domain (corresponding to small wave numbers) but all through the spectra thus putting forth a novel problem - construction of fast algorithms for computations in integers of order $10^{12}$ and more. In this paper we present a generic algorithm for polynomial dispersion functions and illustrate it by application to gravity and planetary waves.

  18. 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

    2013-06-13

    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.

  19. Energy dissipation processes in solar wind turbulence

    E-Print Network [OSTI]

    Wang, Y; Feng, X S; Xu, X J; Zhang, J; Sun, T R; Zuo, P B

    2015-01-01

    Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation cannot be ultimately achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind magnetic reconnection region. We find that the magnetic reconnection region shows a unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for the intermittent multifractal dissipation region scaling around a magnetic reconnection site, and they also have significant implications for the fundamental energy...

  20. Stellar explosions, instabilities, and turbulence

    SciTech Connect (OSTI)

    Drake, R. P.; Kuranz, C. C.; Miles, A. R.; Muthsam, H. J.; Plewa, T.

    2009-04-15

    It has become very clear that the evolution of structure during supernovae is centrally dependent on the pre-existing structure in the star. Modeling of the pre-existing structure has advanced significantly, leading to improved understanding and to a physically based assessment of the structure that will be present when a star explodes. It remains an open question whether low-mode asymmetries in the explosion process can produce the observed effects or whether the explosion mechanism somehow produces jets of material. In any event, the workhorse processes that produce structure in an exploding star are blast-wave driven instabilities. Laboratory experiments have explored these blast-wave-driven instabilities and specifically their dependence on initial conditions. Theoretical work has shown that the relative importance of Richtmyer-Meshkov and Rayleigh-Taylor instabilities varies with the initial conditions and does so in ways that can make sense of a range of astrophysical observations.

  1. Circular polarization of obliquely propagating whistler wave magnetic field

    SciTech Connect (OSTI)

    Bellan, P. M.

    2013-08-15

    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.

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

    E-Print Network [OSTI]

    Moshe Elitzur

    1998-04-03

    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.

  3. FEDERAL ACQUISITION CIRCULAR 2005-56 SUMMARY OF FINAL RULES

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    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: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:FinancingPetroleum12, 2015Executive Order14, 2011 CX-006821: CategoricalJulyCapturingCIRCULAR

  4. Studies of jet mass in dijet and W/Z + jet events

    E-Print Network [OSTI]

    Baringer, Philip S.; Bean, Alice; Benelli, Gabriele; Kenny, R. P. III; Murray, Michael J.; Noonan, Danny; Sanders, Stephen J.; Stringer, Robert W.; Tinti, Gemma; Wood, Jeffrey Scott; Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Aguilo, E.; Bergauer, T.

    2013-05-17

    Invariant mass spectra for jets reconstructed using the anti-k T and CambridgeAachen algorithms are studied for different jet “grooming” techniques in data corresponding to an integrated luminosity of 5 fb(?1), recorded with the CMS detector...

  5. Radio polarization study in protostellar jet

    E-Print Network [OSTI]

    Cécere, Mariana; Araudo, Anabella T; De Colle, Fabio; Esquivel, Alejandro; Carrasco-González, Carlos; Rodríguez, Luis F

    2015-01-01

    Synchrotron radiation is commonly observed associated with shocks of different velocities, ranging from relativistic shocks associated with, e.g., active galactic nuclei, gamma-ray bursts or microquasars to weakly- or non-relativistic flows as those observed e.g. in supernovae and supernova remnants. Recent observations of polarization in protostellar jets are important not only because they extend the range over which the acceleration process works, but also because they allow to measure directly the jet and interstellar magnetic field structure and intensity, thus giving insights on the jet ejection mechanism itself. In this paper, we compute for the first time polarized (synchrotron) and non polarized (thermal-X-ray) synthetic emission maps from axisymmetrical simulations of magnetized protostellar jets. We consider models with different jet velocities and variability, as well as models with toroidal or helical magnetic field. Our simulations show that variable, low-density jets with velocities ~ 1000km/s ...

  6. Jet impact on a soap film

    E-Print Network [OSTI]

    Geoffroy Kirstetter; Christophe Raufaste; Franck Celestini

    2012-08-17

    We experimentally investigate the impact of a liquid jet on a soap film. We observe that the jet never breaks the film and that two qualitatively different steady regimes may occur. The first one is a refraction-like behavior obtained at small incidence angles when the jet crosses the film and is deflected by the film-jet interaction. For larger incidence angles, the jet is absorbed by the film, giving rise to a new class of flow in which the jet undulates along the film with a characteristic wavelength. Besides its fundamental interest, this study presents a new way to guide a micro-metric flow of liquid in the inertial regime and to probe foam stability submitted to violent perturbations at the soap film scale.

  7. Experimental treatment of Quark and Gluon Jets

    E-Print Network [OSTI]

    Sona Pochybova

    2011-07-01

    The separate study of quark and gluon jets is vital for the interpretation of multiple variables behaviour observed in both high-energy hadron and heavy-ion collisions in the present and future experiments. We propose a set of jet-energy dependent cuts to be used to distinguish between quark and gluon jets experimentally based on a Monte-Carlo study of their properties. Further, we introduce the possibility to calibrate these cuts via gamma-jet and multi-jet events, which represent clean production channels for quark and gluon jets, respectively. The calibration can happen on real data and thus, reduces the dependence of the method performance on Monte-Carlo model predictions.

  8. Plasma confinement by circularly polarized electromagnetic field in toroidal geometry

    SciTech Connect (OSTI)

    Svidzinski, Vladimir A. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); and Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2007-10-15

    A novel plasma confinement concept based on plasma confinement by electromagnetic pressure of circularly polarized electromagnetic fields is proposed. Practical implementation of this concept in a toroidal device is suggested. In this concept the confining field frequency is in the lower range such that the size of the device is much smaller than the vacuum wavelength. Most of the previous radio-frequency (rf) confinement concepts of unmagnetized plasma were related to confinement in rf cavities which operated at high frequency for which the size of the cavity is comparable to the wavelength. Operation at lower frequencies simplifies rf design, reduces Ohmic losses in the conducting walls and probably makes application of superconductors for wall materials more feasible. It is demonstrated that circular (or nearly circular) polarization of the electromagnetic field is required for confinement from both the equilibrium and stability considerations. Numerical analysis of plasma confinement for magnetohydrodynamic plasma model in two-dimensional toroidal geometry is performed. Within this model plasma is confined by the applied rf fields and its equilibrium is stable. Technically feasible compact and medium size toroidal plasma confinement devices based on this concept are proposed. Application of this approach to the fusion reactor requires use of superconducting materials for the toroidal shell to reduce the Ohmic losses. Further theoretical and experimental studies are required for a more reliable conclusion about the attractiveness of this plasma confinement concept.

  9. Coupling of twin rectangular supersonic jets

    E-Print Network [OSTI]

    Raman, G.; Taghavi, Ray

    1998-01-01

    J. Fluid Mech. (1998), vol. 354, pp. 123{146. Printed in the United Kingdom c? 1998 Cambridge University Press 123 Coupling of twin rectangular supersonic jets By GANESH RAMAN 1 AND RAY TAGHAVI 2 1 NYMA, Inc., Experimental Fluid Dynamics Section... on twin supersonic jets that screech at a discrete frequency. The present fundamental research program on twin-jet coupling was undertaken to resolve numerous issues underlined by Tam & Seiner (1987), and Morris (1990). Tam & Seiner (1987) pointed...

  10. Nonlinear compressions in merging plasma jets

    SciTech Connect (OSTI)

    Messer, S.; Case, A.; Wu, L.; Brockington, S.; Witherspoon, F. D.

    2013-03-15

    We investigate the dynamics of merging supersonic plasma jets using an analytic model. The merging structures exhibit supersonic, nonlinear compressions which may steepen into full shocks. We estimate the distance necessary to form such shocks and the resulting jump conditions. These theoretical models are compared to experimental observations and simulated dynamics. We also use those models to extrapolate behavior of the jet-merging compressions in a Plasma Jet Magneto-Inertial Fusion reactor.

  11. Jets, frames, and their Cartan geometry

    E-Print Network [OSTI]

    Michael Grasseau

    2006-03-24

    Jets frames, that is a generalisation of ordinary frames on a manifold, are described in a language similar to that of gauge theory. This is achieved by constructing the Cartan geometry of a manifold with respect to the diffeomorphism symmetry. This point of vue allows to give new insights and interpretations in the theory of jet frames, in particular by making an interpolation between ordinary gauge theory concepts and pure jet ones.

  12. In-Medium Properties of Jets

    E-Print Network [OSTI]

    Fuqiang Wang

    2007-07-05

    Modifications of jet-like azimuthal correlations have revealed novel properties of the medium created in relativistic heavy-ion collisions. Experimental results on jet-like 2- and 3-particle correlations, specificly "punch-through" at high transverse momentum, broadening at low and modest transverse momentum, and particularly the possible experimental evidence for conical flow, are reviewed. Future prospects of jet-like correlations and their physics potential are discussed.

  13. Simple scaling laws for astrophysical jets

    E-Print Network [OSTI]

    M. Huarte-Espinosa; S. Mendoza

    2006-07-15

    The idea of a unified model for all astrophysical jets has been considered for quite some time. We present here a few scaling laws relevant to all type of astrophysical jets, analogous to those of \\citet{sams96} which are widely used for astrophysical black holes. We use Buckingham's $ \\Pi $ theorem of dimensional analysis to obtain a family of dimensional relations among the physical quantities associated to astrophysical jets.

  14. Influence of eddydriven jet latitude on North Atlantic jet persistence and blocking frequency in CMIP3 integrations

    E-Print Network [OSTI]

    Hartmann, Dennis

    Influence of eddydriven jet latitude on North Atlantic jet persistence and blocking frequency Atlantic jet latitude is analyzed in 45 CMIP3 integrations. It is demonstrated that models that place the jet equatorward of its observed position have more positively skewed jet latitude distributions, while

  15. Reaction and diffusion in turbulent combustion

    SciTech Connect (OSTI)

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

    1993-12-01

    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.

  16. Meso-scale turbulence in living fluids

    E-Print Network [OSTI]

    Henricus H. Wensink; Jörn Dunkel; Sebastian Heidenreich; Knut Drescher; Raymond E. Goldstein; Hartmut Löwen; Julia M. Yeomans

    2012-08-21

    Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior amongst the simplest forms of life, and is important for fluid mixing and molecular transport on the microscale. The mathematical characterization of turbulence phenomena in active non-equilibrium fluids proves even more difficult than for conventional liquids or gases. It is not known which features of turbulent phases in living matter are universal or system-specific, or which generalizations of the Navier-Stokes equations are able to describe them adequately. Here, we combine experiments, particle simulations, and continuum theory to identify the statistical properties of self-sustained meso-scale turbulence in active systems. To study how dimensionality and boundary conditions affect collective bacterial dynamics, we measured energy spectra and structure functions in dense Bacillus subtilis suspensions in quasi-2D and 3D geometries. Our experimental results for the bacterial flow statistics agree well with predictions from a minimal model for self-propelled rods, suggesting that at high concentrations the collective motion of the bacteria is dominated by short-range interactions. To provide a basis for future theoretical studies, we propose a minimal continuum model for incompressible bacterial flow. A detailed numerical analysis of the 2D case shows that this theory can reproduce many of the experimentally observed features of self-sustained active turbulence.

  17. Diffusion Processes in Turbulent Magnetic Fields

    E-Print Network [OSTI]

    Alex Lazarian

    2007-07-05

    We study of the effect of turbulence on diffusion processes within magnetized medium. While we exemplify our treatment with heat transfer processes, our results are quite general and are applicable to different processes, e.g. diffusion of heavy elements. Our treatment is also applicable to describing the diffusion of cosmic rays arising from magnetic field wandering. In particular, we find that when the energy injection velocity is smaller than the Alfven speed the heat transfer is partially suppressed, while in the opposite regime the effects of turbulence depend on the intensity of driving. In fact, the scale $l_A$ at which the turbulent velocity is equal the Alfven velocity is a new important parameter. When the electron mean free path $\\lambda$ is larger than $l_A$, the stronger the the turbulence, the lower thermal conductivity by electrons is. The turbulent motions, however, induces their own advective transport, that can provide effective diffusivity. For clusters of galaxies, we find that the turbulence is the most important agent for heat transfer. We also show that the domain of applicability of the subdiffusion concept is rather limited.

  18. Effect of Strong External Turbulence on a Wall Jet Boundary Layer

    E-Print Network [OSTI]

    Hunt, Julian

    the design of many types of fluid flow machinery and processes. These effects cause changes in heat transfer

  19. Jet energy calibration at the LHC

    E-Print Network [OSTI]

    Schwartzman, Ariel

    2015-01-01

    Jets are one of the most prominent physics signatures of high energy proton proton (p-p) collisions at the Large Hadron Collider (LHC). They are key physics objects for precision measurements and searches for new phenomena. This review provides an overview of the reconstruction and calibration of jets at the LHC during its first Run. ATLAS and CMS developed different approaches for the reconstruction of jets, but use similar methods for the energy calibration. ATLAS reconstructs jets utilizing input signals from their calorimeters and use charged particle tracks to refine their energy measurement and suppress the effects of multiple p-p interactions (pileup). CMS, instead, combines calorimeter and tracking information to build jets from particle flow objects. Jets are calibrated using Monte Carlo (MC) simulations and a residual in situ calibration derived from collision data is applied to correct for the differences in jet response between data and Monte Carlo. Large samples of dijet, Z+jets, and photon+jet e...

  20. LO, NLO, LO* and jet algorithms

    E-Print Network [OSTI]

    J. Huston

    2010-01-14

    The impact of NLO corrections, and in particular, the role of jet algorithms, is examined for a variety of processes at the Tevatron and LHC.

  1. Jet substructures of boosted polarized top quarks

    E-Print Network [OSTI]

    Yoshio Kitadono; Hsiang-nan Li

    2014-09-05

    We study jet substructures of a boosted polarized top quark, which undergoes the semileptonic decay $t\\to b\\ell\

  2. Observable jets from the BFKL chain

    E-Print Network [OSTI]

    J. Kwiecinski; C. A. M. Lewis; A. D. Martin

    1996-06-19

    We derive a modified form of the BFKL equation which enables the structure of the gluon emissions to be studied in small $x$ deep inelastic scattering. The equation incorporates the resummation of the virtual and unresolved real gluon emissions. We solve the equation to calculate the number of small $x$ deep-inelastic events containing 0,1,2 ...resolved gluon jets, that is jets with transverse momenta $q_{T} > \\mu$. We study the jet decomposition for different choices of the jet resolution parameter $\\mu$.

  3. PHYSICAL PARAMETERS OF STANDARD AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Pucci, Stefano; Romoli, Marco; Poletto, Giannina; Sterling, Alphonse C.

    2013-10-10

    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. Experimental Investigation of Jet Mixing of a Co-Flow Jet Airfoil

    E-Print Network [OSTI]

    Zha, Gecheng

    role in mixing the CFJ with mainflow to transport high kinetic energy from the jet to mainflow so-barrier discharge plasma actuators [9, 10]. However, at present, both ZNMF synthetic jets and plasma actuators net mass flux m Jet mass flow rate u,v,w Velocity components in x-, y-, and z-direction V Velocity

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

    E-Print Network [OSTI]

    Alam, Syed Aftab

    1998-01-01

    Slot Jet Reattachment (SJR) nozzle is an extension of hics.the Radial Jet Reattachment (RJR) concept used to provide high heat and mass transfer while allowing for the control of flow exerted force on the reattachment surface. The SJR is a slot jet...

  6. Detailed characterization of jets in heavy ion collisions using jet fragmentation functions

    E-Print Network [OSTI]

    Ma, Frank Teng

    2013-01-01

    In this thesis the jet fragmentation function of inclusive jets with transverse momentum PT > 100 GeV/c in PbPb collisions is measured for reconstructed charged particles with PT > 1 GeV/c within the jet cone. A data sample ...

  7. Numerical investigation of a transient free jet resembling a laser-produced vapor jet

    E-Print Network [OSTI]

    Budair, Mohammed Omar

    Numerical investigation of a transient free jet resembling a laser-produced vapor jet G.M. Arshed, S.Z. Shuja, B.S. Yilbas *, M.O. Budair Department of Mechanical Engineering, King Fahd University in revised form 29 July 2003 Abstract In the present study, the transiently developing free jet emanating

  8. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect (OSTI)

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.

    2014-09-15

    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.

  9. Autoignition in turbulent two-phase flows

    E-Print Network [OSTI]

    Borghesi, Giulio

    2013-01-08

    . Similar concerns about the limited availability and rising price of conventional fuels have encouraged and motivated research on fuel-efficient engines. Meeting these requirements has proven to be an extraor- dinary challenge, and requires a profound... within the bulk gas, leading to air entrainment. As the cold liquid jet is heated by mixing with the hot oxidizer, a thin sheet of air / fuel vapor mixture is formed around the jet’s periphery. Further entrainment of hot air is responsible for start- ing...

  10. Convectively generated zonal jets by thunderstorms on Jupiter

    E-Print Network [OSTI]

    Zhang, Xi Arthur; Showman, Adam

    2011-01-01

    which assumes the jet streams are the weather pattern con?is adopted to simulate the jet streams, espe- cially theThe wind direction of jet stream is alternating with

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

    E-Print Network [OSTI]

    Trigger, Christopher C; Eilbert, Wesley

    2009-01-01

    and penetration of JP-8 jet fuel and its components. ToxicolContact Dermatitis from Jet Fuel Christopher C. Trigger, MDday. He reported spilling jet fuel on his right lower leg at

  12. MHD jet propagation in the case of DG Tau

    E-Print Network [OSTI]

    Vaidya, Bhargav; Rubini, Francesco; de Colle, Fabio

    2010-01-01

    of art telescopes. Usually jets are observed in forbiddenlike SII, OII etc. One of the jet studied in great detailsis the DG Tau jet. (Lavalley-Fouquet et al. (2000), Dougados

  13. Jet Schemes and Truncated Wedge Schemes Cornelia O. Yuen

    E-Print Network [OSTI]

    Smith, Karen E.

    Jet Schemes and Truncated Wedge Schemes by Cornelia O. Yuen A dissertation submitted in partial of jets and arcs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 A higher dimension analog of arcs and jets . . . . . . . . . . . . . . . . . . . 3 1.3 History

  14. Jet maximization, axis minimization, and stable cone finding

    E-Print Network [OSTI]

    Thaler, Jesse

    Jet finding is a type of optimization problem, where hadrons from a high-energy collision event are grouped into jets based on a clustering criterion. As three interesting examples, one can form a jet cluster that (i) optimizes ...

  15. Effective Field Theory Techniques for Resummation in Jet Physics

    E-Print Network [OSTI]

    Dunn, Nicholas Daniel

    2012-01-01

    QCD corrections to WW+jet production at hadron colliders.al. Substructure of high-p T Jets at the LHC. Phys. Rev. ,decorrelations between QCD jets at all orders. Phys.Lett. ,

  16. Quark Matter 2006: High-pt and jets

    E-Print Network [OSTI]

    van Leeuwen, Marco

    2007-01-01

    Quark Matter 2006: High-p T and jets M van Leeuwen LawrenceT particle production and jets in heavy ion collisions fromp T particle production and jet-like correlations from Quark

  17. JETS OF NUCLEAR MATTER FROM HIGH ENERGY HEAVY ION COLLISIONS

    E-Print Network [OSTI]

    Stocker, H.

    2013-01-01

    be published. Table 1: The jet angle, ejet' relative to theof California. LBL~ll774 Jets of Nuclear Matter from Highreactions. Strongly correlated jets of nuclear matter are

  18. Systemsize dependence of associated yields in hadron-triggered jets

    E-Print Network [OSTI]

    Abelev, Betty

    2010-01-01

    in hadron-triggered jets B.I.Abelev (STARCollaboration)yields in hadron-triggered jets B. I. Abelev 8 , M. M.+Au collisions reveal similar jet-like correlation yields at

  19. Conditional analysis of lifted hydrogen jet diffusion flame experimental data and comparison to laminar flame solutions

    SciTech Connect (OSTI)

    Cheng, T.S. [Department of Mechanical Engineering, Chung Hua University, Hsinchu 300 (China); Wehrmeyer, J.A. [Aerospace Testing Alliance, Arnold Air Force Base, TN 37389 (United States); Pitz, R.W. [Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235 (United States)

    2007-09-15

    Simultaneous point measurements of temperature, mixture fraction, major species, and OH concentrations in a lifted turbulent hydrogen jet flame are reprocessed to obtain the Favre average and conditional mean profiles. Large discrepancies between the Favre average and the ensemble average temperature, H{sub 2}O, and OH mole fractions are found at the lifted flame base, due to density weighting of fairly large samples of unreacted mixtures. Conditional statistics are used to reveal the reaction zone structure in mixture fraction coordinates. The cross-stream dependence of conditional reactive scalars, which is most notable at the lifted flame base and decreases to negligible levels with increasing streamwise positions, could be attributed to radial differences in both the Damkoehler number and the level of partial premixing. Conditional results indicate that the lifted flame is stabilized at the outer region of the jet characterized by low strain rates and lean mixtures. Comparison of the measured conditional mean OH vs H{sub 2}O with a series of stretched laminar partially premixed flame and diffusion flame calculations reveals that strong partial premixing takes place at the lifted flame base and the strain rates vary from a=14,000 to 100 s{sup -1}. The level of partial premixing and the strain rate decrease with increasing downstream locations. The range of estimated scalar dissipation rates ({chi}{approx}1-0.13 s{sup -1}) at a further downstream location (x/D=33.3) is in agreement with reported values and the flame composition reaches an equilibrium condition at x/D=194.4. These results combined with previously reported data provide a benchmark data set for evaluation and refinement of turbulent combustion models for lifted hydrogen jet flame predictions. (author)

  20. Turbulence Spreading and Nonlocal Transport in Magnetized Plasmas

    E-Print Network [OSTI]

    Fominov, Yakov

    transport experiment in tokamak plasmas: heat modulation and fast heat pulse propagation in JET. -- Non

  1. SUR LES CASCADES D'ENERGIE EN ECOULEMENTS TURBULENTS CASCADE OF ENERGY IN TURBULENT FLOWS

    E-Print Network [OSTI]

    Rosa, Ricardo M. S.

    SUR LES CASCADES D'´ENERGIE EN ´ECOULEMENTS TURBULENTS CASCADE OF ENERGY IN TURBULENT FLOWS CIPRIAN energy is transferred from low wave number modes to high wave number modes (L. Onsager (1945)). Such a transfer of energy occurs in a spectral range beyond that of injection of energy, and it underlies the so

  2. Asymmetric Supernovae from Magneto-Centrifugal Jets

    E-Print Network [OSTI]

    J. Craig Wheeler; David L. Meier; James R. Wilson

    2001-12-02

    Strong toroidal magnetic fields generated in stellar collapse can generate magneto-centrifugal jets in analogy to those found in simulations of black hole accretion and explain why all core collapse supernovae are found to be substantially asymmetric and predominantly bi-polar. We describe two phases: the initial LeBlanc-Wilson jet and a subsequent protopulsar or toroidal jet that propagates at about the core escape velocity. The jets will produce bow shocks that tend to expel matter, including iron and silicon, into equatorial tori, accounting for observations of the element distribution in Cas A. A magnetic ``switch'' mechanism may apply in instances of low density and large magnetic field with subsequent increase in the speed and collimation of the toroidal jet, depositing relatively little momentum. The result could be enough infall to form a black hole with a third, highly relativistic jet that could catch up to the protopulsar jet after it has emerged from the star. The interaction of these two jets could generate internal shocks and explain the presence of iron lines in the afterglow. Recent estimates that typical gamma-ray burst energy is about 3x10^50 erg imply either a very low efficiency for conversion of rotation into jets, or a rather rapid turnoff of the jet process even though the black hole still rotates rapidly. Magnetars and ``hypernovae'' might arise in an intermediate parameter regime of energetic jets that yield larger magnetic fields and provide more energy than the routine case, but that are not so tightly collimated that they yield failed supernova. (slightly abridged)

  3. 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.

    2013-06-15

    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.

  4. Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

    SciTech Connect (OSTI)

    Weiland, N.T.; Chen, R.-H.; Strakey, P.A.

    2007-10-01

    Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program’s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

  5. Electrocodeposition of nanoparticle composite films using an impinging jet electrode

    E-Print Network [OSTI]

    Osborne, Steven J.

    2006-01-01

    Particles by Jet Electroplating,” Materials Transactions,of the Impinging Jet Electroplating System……………………….. 3.1Design………………………………………….. 3.5 Electroplating Cell

  6. Interpretation of ageostrophic winds and implications for jet stream maintenance

    E-Print Network [OSTI]

    Wirosoetisno, Djoko

    Interpretation of ageostrophic winds and implications for jet stream maintenance Article Published Version Blackburn, M. (1985) Interpretation of ageostrophic winds and implications for jet stream

  7. Fragmentation, underlying event and jet shapes at the Tevatron...

    Office of Scientific and Technical Information (OSTI)

    Conference: Fragmentation, underlying event and jet shapes at the Tevatron Citation Details In-Document Search Title: Fragmentation, underlying event and jet shapes at the Tevatron...

  8. Boron nitride ablation studies in arc jet facilities (Conference...

    Office of Scientific and Technical Information (OSTI)

    Boron nitride ablation studies in arc jet facilities Citation Details In-Document Search Title: Boron nitride ablation studies in arc jet facilities You are accessing a document...

  9. MEASUREMENTS OF JET VELOCITY IN UNSTRATIFIED AND STRATIFIED FLUIDS

    E-Print Network [OSTI]

    in Civil Engineering Georgia Institute of Technology February 2000 #12;MEASUREMENTS OF JET VELOCITYMEASUREMENTS OF JET VELOCITY IN UNSTRATIFIED AND STRATIFIED FLUIDS A Thesis Presented

  10. Viscous boundary layers of radiation-dominated, relativistic jets. II. The free-streaming jet model

    E-Print Network [OSTI]

    Coughlin, Eric R

    2015-01-01

    We analyze the interaction of a radiation-dominated jet and its surroundings using the equations of radiation hydrodynamics in the viscous limit. In a previous paper we considered the two-stream scenario, which treats the jet and its surroundings as distinct media interacting through radiation viscous forces. Here we present an alternative boundary layer model, known as the free-streaming jet model -- where a narrow stream of fluid is injected into a static medium -- and present solutions where the flow is ultrarelativistic and the boundary layer is dominated by radiation. It is shown that these jets entrain material from their surroundings and that their cores have a lower density of scatterers and a harder spectrum of photons, leading to observational consequences for lines of sight that look "down the barrel of the jet." These jetted outflow models may be applicable to the jets produced during long gamma-ray bursts and super-Eddington phases of tidal disruption events.

  11. Jet propulsion without inertia Saverio E. Spagnoliea

    E-Print Network [OSTI]

    Lauga, Eric

    fluid through pores at its surface. We consider this mechanism of jet propulsion without inertiaJet propulsion without inertia Saverio E. Spagnoliea and Eric Laugab Department of Mechanical corrected 23 August 2010 A body immersed in a highly viscous fluid can locomote by drawing in and expelling

  12. Prediction of Jet Noise Shielding Dimitri Papamoschou*

    E-Print Network [OSTI]

    Papamoschou, Dimitri

    Prediction of Jet Noise Shielding Dimitri Papamoschou* University of California, Irvine, CA 92697, USA This study is motivated by the development of aircraft that use jet noise shielding by the airframe. Current methods to predict shielding from aircraft surfaces rely on formulae developed

  13. Recollimation Shocks in Magnetized Relativistic Jets

    E-Print Network [OSTI]

    Yosuke Mizuno; Jose L. Gomez; Ken-Ichi Nishikawa; Athina Meli; Philip E. Hardee; Luciano Rezzolla

    2015-06-19

    We have performed two-dimensional special-relativistic magnetohydrodynamic simulations of non-equilibrium over-pressured relativistic jets in cylindrical geometry. Multiple stationary recollimation shock and rarefaction structures are produced along the jet by the nonlinear interaction of shocks and rarefaction waves excited at the interface between the jet and the surrounding ambient medium. Although initially the jet is kinematically dominated, we have considered axial, toroidal and helical magnetic fields to investigate the effects of different magnetic-field topologies and strengths on the recollimation structures. We find that an axial field introduces a larger effective gas-pressure and leads to stronger recollimation shocks and rarefactions, resulting in larger flow variations. The jet boost grows quadratically with the initial magnetic field. On the other hand, a toroidal field leads to weaker recollimation shocks and rarefactions, modifying significantly the jet structure after the first recollimation rarefaction and shock. The jet boost decreases systematically. For a helical field, instead, the behaviour depends on the magnetic pitch, with a phenomenology that ranges between the one seen for axial and toroidal magnetic fields, respectively. In general, however, a helical magnetic field yields a more complex shock and rarefaction substructure close to the inlet that significantly modifies the jet structure. The differences in shock structure resulting from different field configurations and strengths may have observable consequences for disturbances propagating through a stationary recollimation shock.

  14. VLBA AND CHANDRA OBSERVATIONS OF JETS IN FRI RADIO GALAXIES: CONSTRAINTS ON JET EVOLUTION

    SciTech Connect (OSTI)

    Kharb, P.; O'Dea, C. P.; Tilak, A.; Baum, S. A.; Haynes, E.; Noel-Storr, J.; Fallon, C.; Christiansen, K.

    2012-07-20

    We present here the results from new Very Long Baseline Array (VLBA) observations at 1.6 and 5 GHz of 19 galaxies of a complete sample of 21 Uppasala General Catalog (UGC) Fanaroff-Riley type I (FRI) radio galaxies. New Chandra data of two sources, viz., UGC 00408 and UGC 08433, are combined with the Chandra archival data of 13 sources. The 5 GHz observations of 10 'core-jet' sources are polarization-sensitive, while the 1.6 GHz observations constitute second-epoch total intensity observations of nine 'core-only' sources. Polarized emission is detected in the jets of seven sources at 5 GHz, but the cores are essentially unpolarized, except in M87. Polarization is detected at the jet edges in several sources, and the inferred magnetic field is primarily aligned with the jet direction. This could be indicative of magnetic field 'shearing' due to jet-medium interaction, or the presence of helical magnetic fields. The jet peak intensity I{sub {nu}} falls with distance d from the core, following the relation, I{sub {nu}}{proportional_to}d{sup a} , where a is typically {approx} - 1.5. Assuming that adiabatic expansion losses are primarily responsible for the jet intensity 'dimming,' two limiting cases are considered: (1) the jet has a constant speed on parsec scales and is expanding gradually such that the jet radius r{proportional_to}d 0{sup .4}; this expansion is, however, unobservable in the laterally unresolved jets at 5 GHz, and (2) the jet is cylindrical and is accelerating on parsec scales. Accelerating parsec-scale jets are consistent with the phenomenon of 'magnetic driving' in Poynting-flux-dominated jets. While slow jet expansion as predicted by case (1) is indeed observed in a few sources from the literature that are resolved laterally, on scales of tens or hundreds of parsecs, case (2) cannot be ruled out in the present data, provided the jets become conical on scales larger than those probed by VLBA. Chandra observations of 15 UGC FRIs detect X-ray jets in 9 of them. The high frequency of occurrence of X-ray jets in this complete sample suggests that they are a signature of a ubiquitous process in FRI jets. It appears that the FRI jets start out relativistically on parsec scales but decelerate on kiloparsec scales, with the X-ray emission revealing the sites of bulk deceleration and particle reacceleration.

  15. Interstellar Turbulence, Cloud Formation and Pressure Balance

    E-Print Network [OSTI]

    Enrique Vazquez-Semadeni

    1998-10-23

    We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the typical values of the densities and magnetic field strengths in the intercloud medium, as well as Larson's velocity dispersion-size scaling relation in clouds may be understood as consequences of the interstellar turbulence. However, the density-size relation appears to only hold for the densest simulated clouds, there existing a large population of small, low-density clouds, which, on the other hand, are hardest to observe. We then discuss several tests and implications of a fully dynamical picture of interstellar clouds. The results imply that clouds are transient, constantly being formed, distorted and disrupted by the turbulent velocity field, with a fraction of these fluctuations undergoing gravitational collapse. Simulated line profiles and estimated cloud lifetimes are consistent with observational data. In this scenario, we suggest it is quite unlikely that quasi-hydrostatic structures on any scale can form, and that the near pressure balance between clouds and the intercloud medium is an incidental consequence of the density field driven by the turbulence and in the presence of appropriate cooling, rather than a driving or confining mechanism.

  16. JET FORMATION IN COUNTERSTREAMING COLLISIONLESS PLASMAS

    SciTech Connect (OSTI)

    Kuramitsu, Y.; Sakawa, Y.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Waugh, J. N.; Woolsey, N. [Department of Physics, University of York, York, YO10 5DD (United Kingdom); Gregory, C. D.; Koenig, M. [Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605, CNRS, CEA, Universite Paris VI, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Morita, T.; Aoki, H. [Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan); Dono, S.; Tanji, H. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Loupias, B., E-mail: kuramitsu-y@ile.osaka-u.ac.j [CEA, DAM, DIF, F-91297 Arpajon (France)

    2009-12-20

    Plasma jet formation was observed in counterstreaming plasmas in a laboratory experiment. In order to model an ambient plasma of astrophysical jets, the counterstreaming plasmas were created by irradiating a double CH-plane target with a high-power laser system. Since the mean free paths of the ions in terms of the counterstreaming motion were larger than the scale length of the experiment, the two-stream interaction of the plasmas was essentially collisionless. The time evolution of the jet collimation was obtained over several shots with different timing by shadowgraphy. When a single CH-plane target was irradiated, no jet collimation was observed. The counterstreaming plasma as an ambient plasma is essential for the jet plasma to collimate.

  17. Atmospheric-pressure plasma jet

    DOE Patents [OSTI]

    Selwyn, Gary S. (Los Alamos, NM)

    1999-01-01

    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.

  18. Particle creation in (2+1) circular dust collapse

    SciTech Connect (OSTI)

    Gutti, Sashideep; Singh, T. P.

    2007-09-15

    We investigate the quantum particle creation during the circularly symmetric collapse of a 2+1 dust cloud, for the cases when the cosmological constant is either zero or negative. We derive the Ford-Parker formula for the 2+1 case, which can be used to compute the radiated quantum flux in the geometric optics approximation. It is shown that no particles are created when the collapse ends in a naked singularity, unlike in the 3+1 case. When the collapse ends in a Banados-Teitelboim-Zanelli black hole, we recover the expected Hawking radiation.

  19. Scour around a circular pile due to oscillatory wave motion 

    E-Print Network [OSTI]

    Wells, Donald Raymond

    1970-01-01

    in a large circular cylinder. Under steady state conditions the fall velocity is called the terminal velocity and the drag on the particle is equal to the submerged weight. Therefore for a sphere ~4/3 d ~s? (22) 20 where V = fall velocity... ANAT. YSIS OF SAND NO. 1 STEVF A&VA& YSIS OF SAND NO. 2 ELEVE ANALYSIS OF SAND NO. 3 C AS A FUViCTION OF REYNOLDS N!Jii(BER. D II', CJP ENT HO'!TON OCCURR1NG DN THF. '' Fi! E BG(JNI!ARY F()R VARIOUS VAL!!!'!S OF PUP LAT IVE l!AVE "!E IGHT I...

  20. Circular dichroism in the electron microscope: Progress and applications (invited)

    SciTech Connect (OSTI)

    Schattschneider, P.; Loeffler, S.; Ennen, I.; Stoeger-Pollach, M.; Verbeeck, J.

    2010-05-15

    According to theory, x-ray magnetic circular dichroism in a synchrotron is equivalent to energy loss magnetic chiral dichroism (EMCD) in a transmission electron microscope (TEM). After a synopsis of the development of EMCD, the theoretical background is reviewed and recent results are presented, focusing on the study of magnetic nanoparticles for ferrofluids and Heusler alloys for spintronic devices. Simulated maps of the dichroic strength as a function of atom position in the crystal allow evaluating the influence of specimen thickness and sample tilt on the experimental EMCD signal. Finally, the possibility of direct observation of chiral electronic transitions with atomic resolution in a TEM is discussed.

  1. Public information circular for shipments of irradiated reactor fuel

    SciTech Connect (OSTI)

    1996-07-01

    This circular provides information on shipment of spent fuel subject to regulation by US NRC. It provides a brief description of spent fuel shipment safety and safeguards requirement of general interest, a summary of data for 1979-1995 highway and railway shipments, and a listing, by State, of recent highway and railway shipment routes. The enclosed route information reflects specific NRC approvals that have been granted in response to requests for shipments of spent fuel. This publication does not constitute authority for carriers or other persons to use the routes described to ship spent fuel, other categories of nuclear waste, or other materials.

  2. Examining A Hypersonic Turbulent Boundary Layer at Low Reynolds Number 

    E-Print Network [OSTI]

    Semper, Michael Thomas

    2013-05-15

    The purpose of the current study was to answer several questions related to hypersonic, low Reynolds number, turbulent boundary layers, of which available data related to turbulence quantities is scarce. To that end, a ...

  3. MICROWAVE IMAGING REFLECTOMETRY FOR THE VISUALIZATION OF TURBULENCE IN TOKAMAKS

    E-Print Network [OSTI]

    1 MICROWAVE IMAGING REFLECTOMETRY FOR THE VISUALIZATION OF TURBULENCE IN TOKAMAKS E. Mazzucato of density fluctuations in tokamaks. The proposed method is based on microwave reflectometry and consists are discussed. Key words: Tokamak, anomalous transport, turbulent fluctuations, microwave imaging reflectometry

  4. Microwave imaging reflectometry for the visualization of turbulence in tokamaks

    E-Print Network [OSTI]

    Mazzucato, Ernesto

    Microwave imaging reflectometry for the visualization of turbulence in tokamaks E. Mazzucato describes the results of an extensive numerical study of microwave reflectometry in tokamaks showing scheme for the global visualization of turbulent fluctuations in tokamaks is described. 1. Introduction

  5. Turbulent burning rates of methane and methane-hydrogen mixtures

    SciTech Connect (OSTI)

    Fairweather, M. [School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Ormsby, M.P.; Sheppard, C.G.W. [School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Woolley, R. [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2009-04-15

    Methane and methane-hydrogen (10%, 20% and 50% hydrogen by volume) mixtures have been ignited in a fan stirred bomb in turbulence and filmed using high speed cine schlieren imaging. Measurements were performed at 0.1 MPa (absolute) and 360 K. A turbulent burning velocity was determined for a range of turbulence velocities and equivalence ratios. Experimental laminar burning velocities and Markstein numbers were also derived. For all fuels the turbulent burning velocity increased with turbulence velocity. The addition of hydrogen generally resulted in increased turbulent and laminar burning velocity and decreased Markstein number. Those flames that were less sensitive to stretch (lower Markstein number) burned faster under turbulent conditions, especially as the turbulence levels were increased, compared to stretch-sensitive (high Markstein number) flames. (author)

  6. Turbulence and internal waves in tidal flow over topography

    E-Print Network [OSTI]

    Gayen, Bishakhdatta

    2012-01-01

    M. C. 2006 An estimate of tidal energy lost to turbulence atcant loss of low-mode tidal energy at 28.9 ? . Geophys. Res.of turbulent kinetic energy over a tidal cycle. Maximum T KE

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

    E-Print Network [OSTI]

    Fuchs, Heidi L

    2005-01-01

    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 ...

  8. Evolution of an initially turbulent stratified shear layer

    E-Print Network [OSTI]

    Brucker, Kyle A.; Sarkar, Sutanu

    2007-01-01

    the turbulent kinetic energy and potential energy are givenbe- tween potential and kinetic energy, is not positive de?kinetic energy that may be trans- ferred to turbulent potential energy.

  9. 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. ...

  10. Small-Scale Forcing of a Turbulent Boundary Layer

    E-Print Network [OSTI]

    Lorkowski, Thomas

    In order to understand the effect of small scale forcing on turbulent flows and its implications on control, an experimental investigation is made into the forcing of the inertial scales in the wall region of a turbulent ...

  11. THE FATE OF PLANETESIMALS IN TURBULENT DISKS WITH DEAD ZONES. I. THE TURBULENT STIRRING RECIPE

    SciTech Connect (OSTI)

    Okuzumi, Satoshi [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Ormel, Chris W., E-mail: okuzumi@geo.titech.ac.jp [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2013-07-01

    Turbulence in protoplanetary disks affects planet formation in many ways. While small dust particles are mainly affected by the aerodynamical coupling with turbulent gas velocity fields, planetesimals and larger bodies are more affected by gravitational interaction with gas density fluctuations. For the latter process, a number of numerical simulations have been performed in recent years, but a fully parameter-independent understanding has not been yet established. In this study, we present simple scaling relations for the planetesimal stirring rate in turbulence driven by magnetorotational instability (MRI), taking into account the stabilization of MRI due to ohmic resistivity. We begin with order-of-magnitude estimates of the turbulence-induced gravitational force acting on solid bodies and associated diffusion coefficients for their orbital elements. We then test the predicted scaling relations using the results of recent ohmic-resistive MHD simulations by Gressel et al. We find that these relations successfully explain the simulation results if we properly fix order-of-unity uncertainties within the estimates. We also update the saturation predictor for the density fluctuation amplitude in MRI-driven turbulence originally proposed by Okuzumi and Hirose. Combination of the scaling relations and saturation predictor allows us to know how the turbulent stirring rate of planetesimals depends on disk parameters such as the gas column density, distance from the central star, vertical resistivity distribution, and net vertical magnetic flux. In Paper II, we apply our recipe to planetesimal accretion to discuss its viability in turbulent disks.

  12. Closure models for turbulent reacting flows

    SciTech Connect (OSTI)

    Dutta, A.; Tarbell, J.M. (Pennsylvania State Univ., University Park, PA (USA). Dept. of Chemical Engineering)

    1989-12-01

    In this paper, a simple procedure based on fast and slow reaction asymptotics has been employed to drive first-order closure models for the nonlinear reaction terms in turbulent mass balances from mechanistic models of turbulent mixing and reaction. The coalescence-redispersion (CRD) model, the interaction by exchange with the mean (IEM) model, the three-environment (3E) model, and the four-environment (4E) model have been used to develop closure equations. The closure models have been tested extensively against experimental data for both single and multiple reactions. The closures based on slow asymptotics for the CRD, 3E and 4E models provide very good predictions of all of the experimental data, while other models available either in the literature or derived here are not adequate. The simple new closure equations developed in this paper may be useful in modeling systems involving turbulent mixing and complex chemical reactions.

  13. RELAXATION PROCESSES IN SOLAR WIND TURBULENCE

    SciTech Connect (OSTI)

    Servidio, S.; Carbone, V.; Gurgiolo, C.; Goldstein, M. L.

    2014-07-10

    Based on global conservation principles, magnetohydrodynamic (MHD) relaxation theory predicts the existence of several equilibria, such as the Taylor state or global dynamic alignment. These states are generally viewed as very long-time and large-scale equilibria, which emerge only after the termination of the turbulent cascade. As suggested by hydrodynamics and by recent MHD numerical simulations, relaxation processes can occur during the turbulent cascade that will manifest themselves as local patches of equilibrium-like configurations. Using multi-spacecraft analysis techniques in conjunction with Cluster data, we compute the current density and flow vorticity and for the first time demonstrate that these localized relaxation events are observed in the solar wind. Such events have important consequences for the statistics of plasma turbulence.

  14. Turbulent density fluctuations in the solar wind

    E-Print Network [OSTI]

    Ingale, Madhusudan

    2015-01-01

    Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and quantify the relative error introduced by the approximations. We show that the regimes where GSF predictions are accurate than those of its asymptotic approximations is not only of practical relevance, but are where inner scale effects influence the estimate of the scatter-broadening. Thus we propose that GSF should henceforth be used for scatter broadening calculations and estimates of quantities characterizing density turbulence in the solar corona and solar wind. In the next part of this thesis we use measurements of density turbulence in the solar wind from previously publish observations of radio wave scattering and interplanetary scintillations. Density fluctuations are inferred using the GSF for radio scattering data and existing analysis methods for IPS. Assuming that...

  15. Interpreting Power Anisotropy Measurements in Plasma Turbulence

    E-Print Network [OSTI]

    Chen, C H K; Horbury, T S; Schekochihin, A A

    2009-01-01

    A relationship between power anisotropy and wavevector anisotropy in turbulent fluctuations is derived. This can be used to interpret plasma turbulence measurements, for example in the solar wind. If fluctuations are anisotropic in shape then the ion gyroscale break point in spectra in the directions parallel and perpendicular to the magnetic field would not occur at the same frequency, and similarly for the electron gyroscale break point. This is an important consideration when interpreting solar wind observations in terms of anisotropic turbulence theories. Model magnetic field power spectra are presented assuming a cascade of critically balanced Alfven waves in the inertial range and kinetic Alfven waves in the dissipation range. The variation of power anisotropy with scale is compared to existing solar wind measurements and the similarities and differences are discussed.

  16. Boundary Plasma Turbulence Simulations for Tokamaks

    SciTech Connect (OSTI)

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

    2008-05-15

    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.

  17. 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)

    2014-09-15

    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.

  18. Wave turbulence served up on a plate

    E-Print Network [OSTI]

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

    2009-10-28

    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.

  19. Turbulent mixing of a slightly supercritical Van der Waals fluid at Low-Mach number

    E-Print Network [OSTI]

    Battista, Francesco; Casciola, Carlo Massimo

    2014-01-01

    Supercritical fluids near the critical point are characterized by liquid-like densities and gas-like transport properties. These features are purposely exploited in different contexts ranging from natural products extraction/fractionation to aerospace propulsion. Large part of studies concerns this last context, focusing on the dynamics of supercritical fluids at high Mach number where compressibility and thermodynamics strictly interact. Despite the widespread use also at low Mach number, the turbulent mixing properties of slightly supercritical fluids have still not investigated in detail in this regime. This topic is addressed here by dealing with Direct Numerical Simulations (DNS) of a coaxial jet of a slightly supercritical Van der Waals fluid. Since acoustic effects are irrelevant in the Low Mach number conditions found in many industrial applications, the numerical model is based on a suitable low-Mach number expansion of the governing equation. According to experimental observations, the weakly superc...

  20. Statistical theory of turbulent incompressible multimaterial flow

    SciTech Connect (OSTI)

    Kashiwa, B.

    1987-10-01

    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.

  1. Submerged jet mixing in nuclear waste tanks: a correlation for jet velocity

    SciTech Connect (OSTI)

    Daas, M.; Srivastava, R.; Roelant, D. [Applied Research Center, Florida International Univ., Miami, FL (United States)

    2007-07-01

    Experimental studies were carried out in jet-stirred slurry tanks to correlate the influence of nozzle diameter, initial jet flow velocity, submerged depth of jet, tank diameter and slurry properties on the jet axial velocity. The tanks used in the experimental work had diameters of 0.3 m (1-ft) and 2.13 m (7-ft). The fluids emerged from nozzles of 0.003 m and 0.01 m in diameter, 1/8-inch and 3/8-inch respectively. The examined slurries were non-Newtonian and contained 5 weight percent total insoluble solids. The axial velocities along the centerline of a submerged jet stream were measured at different jet flow rates and at various distances from the nozzle orifice (16 to 200 nozzle diameters) utilizing electromagnetic velocity meter. A new simplified correlation was developed to describe the jet axial velocity in submerged jet stirred tanks utilizing more than 350 data points. The Buckingham Pi theorem and non-linear regression method of multivariate approximation, in conjunction with the Gauss-Jordan elimination method, were used to develop the new correlation. The new correlation agreed well with the experimental data obtained from the current study. Good agreement was also possible with literature data except at large distances from the nozzle as the model slightly overestimated the jet axial velocity. The proposed correlation incorporates the contributions of system geometry, fluid properties, and external forces. Furthermore, it provides reasonable estimates of jet axial velocity. (authors)

  2. Intra-jet shocks in two counter-streaming, weakly collisional plasma jets

    SciTech Connect (OSTI)

    Ryutov, D. D.; Kugland, N. L.; Park, H.-S.; Plechaty, C.; Remington, B. A.; Ross, J. S.

    2012-07-15

    Counterstreaming laser-generated plasma jets can serve as a test-bed for the studies of a variety of astrophysical phenomena, including collisionless shock waves. In the latter problem, the jet's parameters have to be chosen in such a way as to make the collisions between the particles of one jet with the particles of the other jet very rare. This can be achieved by making the jet velocities high and the Coulomb cross-sections correspondingly low. On the other hand, the intra-jet collisions for high-Mach-number jets can still be very frequent, as they are determined by the much lower thermal velocities of the particles of each jet. This paper describes some peculiar properties of intra-jet hydrodynamics in such a setting: the steepening of smooth perturbations and shock formation affected by the presence of the 'stiff' opposite flow; the role of a rapid electron heating in shock formation; ion heating by the intrajet shock. The latter effect can cause rapid ion heating which is consistent with recent counterstreaming jet experiments by Ross et al.[Phys. Plasmas 19, 056501 (2012)].

  3. The Motion Of A Spring Released From Uniform Circular Motion

    E-Print Network [OSTI]

    Dooling, Thomas; Carnaghi, Matthew; Titus, Aaron

    2015-01-01

    A weak spring is connected at one end to a rotor turning at constant angular velocity. The spring extends to a stretched length as determined by the spring mass, rest length, spring constant, rotor radius and rotor angular velocity. When released from the rotor, the inner end of the spring pulls away as expected, causing a wave to travel down the spring as it collapses. During this time interval, the outer end of the spring continues to move along its original circular path in uniform circular motion, as if the spring were still connected to the rotor. This is analogous to the effect of a hanging Slinky released from rest whose bottom end remains at a fixed position above the ground until a wave from the top of the Slinky reaches the bottom of the Slinky. Values from a numerical model and measurements from video analysis show that upon release the inner end travels along a circle of similar radius as the outer end. The effect appears as a series of alternating semi-circles. In addition, the simulation and dat...

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

    SciTech Connect (OSTI)

    Kwon, Jungmi; Tamura, Motohide; Hashimoto, Jun; Kusakabe, Nobuhiko; Kandori, Ryo; Lucas, Phil W.; Hough, James H.; Nakajima, Yasushi; Nagayama, Takahiro; Nagata, Tetsuya

    2013-03-01

    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.

  5. Turbulence Intensity Comparisons for Pipes with/without Welds

    E-Print Network [OSTI]

    McDonald, Kirk

    Turbulence Intensity Comparisons for Pipes with/without Welds Oct. 24, 2012 Yan Zhan 1 #12;Outline · Line Plot of TI at the Pipe Exit · Contour of Turbulence Intensity (Page 4 - 9) ­ with a weld - 3.2M ­ with a weld ­ 2.5M · Contour of Turbulence Intensity (Page 10 - 15) ­ with a weld - 3.2M ­ without a weld ­ 3

  6. Turbulent Wind Fields for Gaseous Phenomena Eugene Fiume 0

    E-Print Network [OSTI]

    Toronto, University of

    Turbulent Wind Fields for Gaseous Phenomena Jos Stam Eugene Fiume 0 Department of Computer Science of smoke, steam, mist and water re­ acting to a turbulent field such as wind is an attractive, and realistic illumina­ tion. We present a model for turbulent wind flow having a deterministic component

  7. The Effect of Magnetic Turbulence Energy Spectra and

    E-Print Network [OSTI]

    Ng, Chung-Sang

    The Effect of Magnetic Turbulence Energy Spectra and Pickup Ions on the Heating of the Solar Wind ADimensionless parameter: [Iroshnikov 1963, Kraichnan 1965] #12;Solar wind turbulence model The steady state solar wind turbulence model developed by [Matthaeus et al. 1994, 1996] and later developments: Steady

  8. Intermittency in Turbulent Diffusion Models with a Mean Gradient

    E-Print Network [OSTI]

    Majda, Andrew J.

    Intermittency in Turbulent Diffusion Models with a Mean Gradient Andrew J Majda and Xin T TongE30, 62G32 Submitted to: Nonlinearity 1. Introduction Turbulent diffusion is the transportation and diffusion. Its application ranges from the spread of hazardous plumes and mixing properties of turbulent

  9. Structure and Dynamics of Fuel Jets Injected into a High-Temperature Subsonic Crossflow: High-Data-Rate Laser Diagnostic Investigation under Steady and Oscillatory Conditions

    SciTech Connect (OSTI)

    Lucht, Robert; Anderson, William

    2015-01-23

    An investigation of subsonic transverse jet injection into a subsonic vitiated crossflow is discussed. The reacting jet in crossflow (RJIC) system investigated as a means of secondary injection of fuel in a staged combustion system. The measurements were performed in test rigs featuring (a) a steady, swirling crossflow and (b) a crossflow with low swirl but significant oscillation in the pressure field and in the axial velocity. The rigs are referred to as the steady state rig and the instability rig. Rapid mixing and chemical reaction in the near field of the jet injection is desirable in this application. Temporally resolved velocity measurements within the wake of the reactive jets using 2D-PIV and OH-PLIF at a repetition rate of 5 kHz were performed on the RJIC flow field in a steady state water-cooled test rig. The reactive jets were injected through an extended nozzle into the crossflow which is located in the downstream of a low swirl burner (LSB) that produced the swirled, vitiated crossflow. Both H2/N2 and natural gas (NG)/air jets were investigated. OH-PLIF measurements along the jet trajectory show that the auto-ignition starts on the leeward side within the wake region of the jet flame. The measurements show that jet flame is stabilized in the wake of the jet and wake vortices play a significant role in this process. PIV and OH–PLIF measurements were performed at five measurement planes along the cross- section of the jet. The time resolved measurements provided significant information on the evolution of complex flow structures and highly transient features like, local extinction, re-ignition, vortex-flame interaction prevalent in a turbulent reacting flow. Nanosecond-laser-based, single-laser-shot coherent anti-Stokes Raman scattering (CARS) measurements of temperature and H2 concentraiton were also performed. The structure and dynamics of a reacting transverse jet injected into a vitiated oscillatory crossflow presents a unique opportunity for applying advanced experimental diagnostic techniques with increasing fidelity for the purposes of computational validation and model development. Numerical simulation of the reacting jet in crossflow is challenging because of the complex vortical structures in the flowfield and compounded by an unsteady crossflow. The resulting benchmark quality data set will include comprehensive, accurate measurements of mean and fluctuating components of velocity, pressure, and flame front location at high pressure and with crossflow conditions more representative of modern gas turbine engines. A proven means for producing combustion dynamics is used for the performing combustion instability experimental study on a reacting jet in crossflow configuration. The method used to provide an unsteady flowfield into which the transverse jet is injected is a unique and novel approach that permits elevated temperature and pressure conditions. A model dump combustor is used to generate and sustain an acoustically oscillating vitiated flow that serves as the crossflow for transverse jet injection studies. A fully optically accessible combustor test section affords full access surrounding the point of jet injection. High speed 10 kHz planar measurements OH PLIF and high frequency 180 kHz wall pressure measurements are performed on the injected reacting transverse jet and surrounding flowfield, respectively, under simulated unstable conditions. The overlay of the jet velocity flowfield and the flame front will be investigated using simultaneous 10 kHz OH PLIF and PIV in experiments to be performed in the near future.

  10. Computational aspects of astrophysical MHD and turbulence

    E-Print Network [OSTI]

    Axel Brandenburg

    2001-09-27

    The advantages of high-order finite difference scheme for astrophysical MHD and turbulence simulations are highlighted. A number of one-dimensional test cases are presented ranging from various shock tests to Parker-type wind solutions. Applications to magnetized accretion discs and their associated outflows are discussed. Particular emphasis is placed on the possibility of dynamo action in three-dimensional turbulent convection and shear flows, which is relevant to stars and astrophysical discs. The generation of large scale fields is discussed in terms of an inverse magnetic cascade and the consequences imposed by magnetic helicity conservation are reviewed with particular emphasis on the issue of alpha-quenching.

  11. Scattering Analysis of Open-Ended Circular Waveguide Cavity with Corrugations

    E-Print Network [OSTI]

    Myung, Noh-Hoon

    (RAM) [3]. We suggest a method for the scattering effect reduction by the jet engine in the new method with scattering matrix method. This analysis structure has applicability to a jet engine for reduction of a scattering effect by the jet engine inlet. To analyze the structure, mode-matching method

  12. ATLAS - LHC Run 2 jet performance

    E-Print Network [OSTI]

    Varouchas, Dimitris; The ATLAS collaboration

    2015-01-01

    Jet energy scale systematic uncertainties and jet cleaning for early 2015 data analyses Many searches and measurements using early 2015 data rely on the accurate determination of the jet energy measurement and the rejection of jets arising from non collision backgrounds and detector faults. In this talk, the procedure used to establish the systematic uncertainties on the jet energy scale and resolutions for 2015 data analysis will be described. The uncertainties will be compared to the uncertainties achieved for 2012 data analyses. In addition, variables related to the presence of beam backgrounds and detector imperfections will be shown, comparing them in early data and MC simulations. Based on these studies, selection cuts to reject these backgrounds will be defined and their efficiency to select signal and background jets studied in data. Inputs to jet reconstruction and boosted object tagging with the ATLAS detector at sqrt(s)=13 TeV The LHC has recently concluded a 2-year-long shutdown delivering once mo...

  13. Modulational instability of Rossby and drift waves and generation of zonal jets

    E-Print Network [OSTI]

    Colm Connaughton; Balu Nadiga; Sergey Nazarenko; Brenda Quinn

    2009-05-14

    We study the modulational instability of geophysical Rossby and plasma drift waves within the Charney-Hasegawa-Mima (CHM) model both theoretically, using truncated (four-mode and three-mode) models, and numerically, using direct simulations of CHM equation in the Fourier space. The linear theory predicts instability for any amplitude of the primary wave. For strong primary waves the most unstable modes are perpendicular to the primary wave, which correspond to generation of a zonal flow if the primary wave is purely meridional. For weaker waves, the maximum growth occurs for off-zonal inclined modulations. For very weak primary waves the unstable waves are close to being in three-wave resonance with the primary wave. The nonlinear theory predicts that the zonal flows generated by the linear instability experience pinching into narrow zonal jets. Our numerical simulations confirm the theoretical predictions of the linear theory as well as of the nonlinear pinching. We find that, for strong primary waves, these narrow zonal jets further roll up into Karman-like vortex streets. On the other hand, for weak primary waves, the growth of the unstable mode reverses and the system oscillates between a dominant jet and a dominate primary wave. The 2D vortex streets appear to be more stable than purely 1D zonal jets, and their zonal-averaged speed can reach amplitudes much stronger than is allowed by the Rayleigh-Kuo instability criterion for the 1D case. We find that the truncation models work well for both the linear stage and and often even for the medium-term nonlinear behavior. In the long term, the system transitions to turbulence helped by the vortex-pairing instability (for strong waves) and by the resonant wave-wave interactions (for weak waves).

  14. MUSKHELISHVILI'S METHOD APPLIED TO ELLIPTICAL AND LUBRICATED CIRCULAR INCLUSIONS IN GENERAL SHEAR

    E-Print Network [OSTI]

    Podladchikov, Yuri

    MUSKHELISHVILI'S METHOD APPLIED TO ELLIPTICAL AND LUBRICATED CIRCULAR INCLUSIONS IN GENERAL SHEAR and Elliptical Inclusions, Lubricated Inclusions, Mantled Inclusions, Pure and Simple Shear, Viscous Rheology

  15. On the injectivity of the circular Radon transform arising in thermoacoustic

    E-Print Network [OSTI]

    On the injectivity of the circular Radon transform arising in thermoacoustic tomography Gaik, thermoacoustic tomogra­ phy (TAT or TCT) and its sibling photoacoustic tomography (PAT) have already made

  16. Circular grating interferometer for mapping transverse coherence area of X-ray beams

    SciTech Connect (OSTI)

    Shi, Xianbo, E-mail: xshi@aps.anl.gov; Marathe, Shashidhara; Wojcik, Michael J.; Kujala, Naresh G.; Macrander, Albert T.; Assoufid, Lahsen [Advanced Photon Source, Argonne National Laboratory, 9700 S Cass Ave, Lemont, Illinois 60439 (United States)

    2014-07-28

    A circular grating interferometer was used to map the transverse coherence area of an X-ray beam. Due to the radial symmetry of the circular grating, coherence lengths along all transverse directions were obtained simultaneously by measuring the visibility decay of interferograms recorded at different distances behind a single circular ?/2 phase grating. The technique is model-free and provides direct measurement of the complex coherence factor of the beam. The use of a circular grating also enables the unique capability of measuring the source shape profile. Sensitivity of this technique was demonstrated by detecting the small source tilt of a few degrees.

  17. HYDROGEN PEROXIDE DETECTED ON MARS IAU Circular 8254 9 December 2003

    E-Print Network [OSTI]

    Atreya, Sushil

    HYDROGEN PEROXIDE DETECTED ON MARS IAU Circular 8254 9 December 2003 Central Bureau. Wong, University of Michigan, report: "On June 20, we made an unambiguous detection of hydrogen

  18. Evaluation of Jet Algorithms in the Search for Sources of

    E-Print Network [OSTI]

    Erdmann, Martin

    Evaluation of Jet Algorithms in the Search for Sources of Ultra-High-Energy Cosmic Rays von-Energy-Correlations . . . . . . . . . . . . . . . . . . . 5 2 Jet Algorithms 7 2.1 Jet Algorithms in High-Energy Physics . . . . . . . . . . . . . . . . . 7 2.2 The SISCone-Jet-Algorithm . . . . . . . . . . . . . . . . . . . . . . . 8 2.2.1 The Search for Stable Cones

  19. http://smap.jpl.nasa.gov Jet Propulsion Laboratory

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    http://smap.jpl.nasa.gov Jet Propulsion Laboratory California Institute of Technology SMAP SAR* On-Orbit Misalignment Calibration Dynamics & Control, Jet Propulsion Laboratory, Pasadena, CA *Synthetic Aperture Radar #12;Jet Propulsion Laboratory California Institute of Technology Jet Propulsion Laboratory California

  20. Rossby waves and the jet Schematic from Vallis

    E-Print Network [OSTI]

    Frierson, Dargan

    everywhere. Generates a jet stream in stirred region. This model also has an annular mode! #12;Phase speedRossby waves and the jet Schematic from Vallis: #12;Rossby waves and the jet Schematic from in recent shift in observations and models of SH: Faster eddies in obs and in model #12;How will jet shift