Powered by Deep Web Technologies
Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Turbulent round jet under gravity waves  

E-Print Network [OSTI]

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

Ryu, Yong Uk

2002-01-01T23:59:59.000Z

2

CONTROL OF COHERENT STRUCTURE IN COAXIAL SWIRLING TURBULENT JETS  

E-Print Network [OSTI]

stronger effect than the pilot jet itself, leading to an almost entire removal of coherent structures. 2.2. Flow Instability Swirl is naturally presented in the exhaust from a turbine or an axial flow pump, and may be deliberately generated... ............................................................................................. 1 2. REVIEW OF LITERATURE............................................................................. 6 2.1. Turbulent Jets with Swirl................................................................................ 7 2.2. Flow Instability...

Lee, Wonjoong

2008-01-01T23:59:59.000Z

3

Dynamics of quasi-two-dimensional turbulent jets  

E-Print Network [OSTI]

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

Landel, Julien Rémy Dominique Gérard

2012-11-13T23:59:59.000Z

4

Numerical simulation of turbulent jet primary breakup in Diesel engines  

E-Print Network [OSTI]

Numerical simulation of turbulent jet primary breakup in Diesel engines Peng Zeng1 Marcus Herrmann and Aerospace Engineering Arizona State University "Micro-Macro Modelling and Simulation of Liquid-Vapour Flows" IRMA Strasbourg, 23.Jan.2008 #12;Introduction DNS of Primary Breakup in Diesel Injection Phase

Helluy, Philippe

5

An experimental study of jet impingement on a circular cylinder  

E-Print Network [OSTI]

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

Potts, Dennis Wayne

2012-06-07T23:59:59.000Z

6

Stability Regimes of Turbulent Nitrogen-Diluted Hydrogen Jet Flames  

SciTech Connect (OSTI)

One option for combustion in zero-emission Integrated Gasification Combined Cycle (IGCC) power plants is non-premixed combustion of nitrogen-diluted hydrogen in air. An important aspect to non-premixed combustion is flame stability or anchoring, though only a few fundamental stability studies of these flames have taken place to date. The following paper presents the results of experiments investigating the effects of nitrogen diluent fraction, jet diameter, and exit velocity on the static stability limits of a turbulent hydrogen jet flame issuing from a thin-lipped tube into a quiescent atmosphere. Four different stability limits are observed: detachment from the burner lip, reattachment to the burner lip, transition from a laminar lifted flame base to blowout or to a turbulent lifted flame, and transition from a turbulent lifted flame to blowout. The applicability of existing theories and correlations to the stability results is discussed. These results are an important step in assessing the viability of a non-premixed combustion approach using hydrogen diluted with nitrogen as a fuel.

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

2007-03-01T23:59:59.000Z

7

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

E-Print Network [OSTI]

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

Ortiz, Alejandra C

2012-01-01T23:59:59.000Z

8

Properties of vortices in the self-similar turbulent jet A. Agrawal, A.K. Prasad  

E-Print Network [OSTI]

to the fundamental importance of their flow physics. Consequently, their time-averaged velocity profiles, spread rate turbulent axisymmetric jet. The velocity fields were high-pass filtered to expose the vortical structures, the strongest eddies in the high-pass fil- tered field occur near the jet axis. The average circulation

Prasad, Ajay K.

9

Large Eddy Simulation of spark ignition in a turbulent methane jet  

E-Print Network [OSTI]

and propagation and (4) stabilization. In the context of laser and electrical spark ignition (which is the scope applications of laser ignition and comparison with standard spark plug devices. Phuoc et al. [5] presentLarge Eddy Simulation of spark ignition in a turbulent methane jet G. Lacaze a , E. Richardson b

Paris-Sud XI, Université de

10

Magnetohydrodynamic lattice Boltzmann simulations of turbulence and rectangular jet flow  

E-Print Network [OSTI]

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...

Riley, Benjamin Matthew

2009-05-15T23:59:59.000Z

11

Radiation from relativistic jets in turbulent magnetic fields  

SciTech Connect (OSTI)

Using our new 3-D relativistic electromagnetic particle (REMP) code parallelized with MPI, we have investigated long-term particle acceleration associated with an relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations have been performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. The acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value. Behind the bow shock in the jet shock strong electromagnetic fields are generated. These fields may lead to the afterglow emission. We have calculated the time evolution of the spectrum from two electrons propagating in a uniform parallel magnetic field to verify the technique.

Nishikawa, K.-I.; Mizuno, Y. [National Space Science and Technology Center, Huntsville, AL 35805 (United States); Medvedev, M. [Department of Physics and Astronomy, University of Kansas, KS 66045 (United States); Zhang, B. [Department of Physics, University of Nevada, Las Vegas, NV 89154 (United States); Hardee, P. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Niemiec, J. [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Nordlund, A.; Frederiksen, J. [Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Oe (Denmark); Sol, H. [LUTH, Observatore de Paris-Meudon, 5 place Jules Jansen, 92195 Meudon Cedex (France); Fishman, G. J. [NASA/MSFC, Huntsville, AL 35805 (United States)

2009-05-25T23:59:59.000Z

12

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

SciTech Connect (OSTI)

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

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

1995-05-01T23:59:59.000Z

13

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

SciTech Connect (OSTI)

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.

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

2010-10-01T23:59:59.000Z

14

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

SciTech Connect (OSTI)

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

NguyenLe, Q.

1998-06-26T23:59:59.000Z

15

Validity of several approximations for the turbulent buoyant jet in a stagnant neutrally-stratified ambient  

SciTech Connect (OSTI)

A series of approximations are usually made in deriving integral model equations for the dispersion of a round turbulent buoyant jet into a stagnant neutrally-stratified ambient fluid. The magnitudes of differences in model predictions caused by making four of these approximations are calculated as a function of the initial densimetric Froude number and the initial relative density difference. The four approximations studied are (1) the Boussinesq approximation, (2) the use of a common Gaussian width for both mean axial velocity and mean temperature (or concentration) excess, (3) the neglect of fluctuation-correlation terms, and (4) the assumption of a linear relationship between excess density and excess temperature (or concentration). The four approximations are studied singly and then cumulatively as the predictions of the two models, one with and one without all approximations, are compared to seven low Froude number data cases. Results show that the Boussinesq approximation produces percentage differences in predictions which are about half of the initial relative density difference expressed in percentage. Use of a common Gaussian width for velocity and temperature produces differences from 6% to 30% depending on the entrainment assumption used. Fluctuation correlation effects rarely exceed 8%. Lastly, at Froude numbers below about 10 the correct nonlinear equation of state must often be used for heated waste jets to acheive accurate results, and the correct air equation of state may also be needed for low Froude number heated air jets, depending on the initial diameter and velocity.

Ponce, T.C.

1982-01-01T23:59:59.000Z

16

Numerical study of fluid flow and heat transfer characteristics in an intermittent turbulent impinging round jet  

Science Journals Connector (OSTI)

Abstract The flow structure and heat transfer of the air pulsed turbulent impinging jet are studied numerically. The gas turbulence is modelled with the Reynolds stress model. The effects of pulse frequency, ratio of on time to total cycle time, distance between pipe outlet and impinging flat plate and Reynolds number on heat transfer are numerically studied. The impingement heat transfer increases with distance from the pipe edge and target surface. The heat transfer decreases at high distance from the pipe edge and target surface. An increase in the Reynolds number causes reduction of heat transfer enhancement. Reduced heat transfer in comparison with the steady-state impinging jet is typical in the range of low frequencies of the pulse impinging jet.

M.A. Pakhomov; V.I. Terekhov

2015-01-01T23:59:59.000Z

17

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)

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.

Mansour, A.; Chigier, N.

1993-12-01T23:59:59.000Z

18

Stability characteristics of non-premixed turbulent jet flames of hydrogen and syngas blends with coaxial air  

Science Journals Connector (OSTI)

The stability characteristics of attached hydrogen (H2) and syngas (H2/CO) turbulent jet flames with coaxial air were studied experimentally. The flame stability was investigated by varying the fuel and air stream velocities. Effects of the coaxial nozzle diameter, fuel nozzle lip thickness and syngas fuel composition are addressed in detail. The detachment stability limit of the syngas single jet flame was found to decrease with increasing amount of carbon monoxide in the fuel. For jet flames with coaxial air, the critical coaxial air velocity leading to flame detachment first increases with increasing fuel jet velocity and subsequently decreases. This non-monotonic trend appears for all syngas composition herein investigated (50/50 ? 100/0% H2/CO). OH? chemiluminescence imaging was performed to qualitatively identify the mechanisms responsible for the flame detachment. For all fuel compositions, local extinction close to the burner rim is observed at lower fuel velocities (ascending stability limit), while local flame extinction downstream of the burner rim is observed at higher fuel velocities (descending stability limit). Extrema of the non-monotonic trends appear to be identical when the nozzle fuel velocity is normalized by the critical fuel velocity obtained for the single jet cases.

Jeongjae Hwang; Nicolas Bouvet; Kitae Sohn; Youngbin Yoon

2013-01-01T23:59:59.000Z

19

A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow  

SciTech Connect (OSTI)

Direct numerical simulation (DNS) of the near-field of a three-dimensional spatially-developing turbulent ethylene jet flame in highly-heated coflow is performed with a reduced mechanism to determine the stabilization mechanism. The DNS was performed at a jet Reynolds number of 10,000 with over 1.29 billion grid points. The results show that auto-ignition in a fuel-lean mixture at the flame base is the main source of stabilization of the lifted jet flame. The Damkoehler number and chemical explosive mode (CEM) analysis also verify that auto-ignition occurs at the flame base. In addition to auto-ignition, Lagrangian tracking of the flame base reveals the passage of large-scale flow structures and their correlation with the fluctuations of the flame base similar to a previous study (Yoo et al., J. Fluid Mech. 640 (2009) 453-481) with hydrogen/air jet flames. It is also observed that the present lifted flame base exhibits a cyclic 'saw-tooth' shaped movement marked by rapid movement upstream and slower movement downstream. This is a consequence of the lifted flame being stabilized by a balance between consecutive auto-ignition events in hot fuel-lean mixtures and convection induced by the high-speed jet and coflow velocities. This is confirmed by Lagrangian tracking of key variables including the flame-normal velocity, displacement speed, scalar dissipation rate, and mixture fraction at the stabilization point.

Yoo, Chun S [Sandia National Laboratories (SNL)

2011-01-01T23:59:59.000Z

20

Jet Jet Jet Jet  

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

protons protons top quark bottom quark muon top quark antiprotons bottom quark low energy muon quark quark - W boson + Jet Jet Jet Jet neutrino W boson particles antiparticles A Top Antitop Quark Event from the D-Zero Detector at Fermilab muon low energy muon Jet Jet Jet Jet particles antiparticles Particles Seen by the D-Zero Detector at Fermilab in a Top Antitop Quark Event. DST LEGO 16-JUL-1996 15:32 Run 92704 Event 14022 9-JUL-1995 13:17 MUON MUON Miss ET ET DST ETA-PHI 4 MUON 1 MISS ET 4 JET (HAD) (EM) D-Zero Detector at Fermi National Accelerator Laboratory Lego Plot CAL+TKS END VIEW 16-JUL-1996 15:33 Run 92704 Event 14022 9-JUL-1995 13:17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

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

SciTech Connect (OSTI)

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

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

2012-01-01T23:59:59.000Z

22

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

E-Print Network [OSTI]

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

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

2014-10-03T23:59:59.000Z

23

Turbulence  

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

Turbulence Turbulence in Alcator C-Mod and Wendelstein 7-AS plasmas during controlled confinement transitions N.P.Basse, E.M.Edlund, C.L.Fiore, M.J.Greenwald, A.E.Hubbard, J.W.Hughes, J.H.Irby, G.J.Kramer 1 , L.Lin, Y.Lin, A.G.Lynn 2 , E.S.Marmar, D.R.Mikkelsen 1 , D.Mossessian, P.E.Phillips 2 , M.Porkolab, J.E.Rice, W.L.Rowan 2 , J.A.Snipes, J.L.Terry, S.M.Wolfe, S.J.Wukitch, K.Zhurovich, S.Zoletnik 3 and the C-Mod and W7-AS 4 Teams MIT Plasma Science and Fusion Center, Cambridge, USA 1 Princeton Plasma Physics Laboratory, Princeton, USA 2 University of Texas at Austin, Austin, USA 3 KFKI-RMKI, EURATOM Association, Budapest, Hungary 4 Max-Planck-Institut f¨ ur Plasmaphysik, EURATOM Association, Greifswald, Germany At certain values of the edge rotational transform, ι a = 1/q a , the confinement time of plasmas in the Wendelstein 7-AS (W7-AS) stellarator was found to

24

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

E-Print Network [OSTI]

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

Shepherd, Theodore Gordon

1984-01-01T23:59:59.000Z

25

A theory for radial jet reattachment flow  

E-Print Network [OSTI]

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

Hadden, Lynne Loise

2012-06-07T23:59:59.000Z

26

Turbulent heat transfer characteristics in a circular tube and thermal properties of n-decane-in-water nanoemulsion fluids and micelles-in-water fluids  

Science Journals Connector (OSTI)

Abstract We carry out experimental studies of turbulent convective heat transfer of several n-decane-in-water nanoemulsions and micelles-in-water fluids. We characterize the viscosity and thermal properties of the nanofluids, and the nanoparticle distributions and shapes with various techniques, including transmission electron microscopy. We find that the thermal conductivity of the nanofluids is lower than that of the base fluid, and the conductivity shows no anomalous behavior. Despite this we find that the average Nusselt numbers and convective heat transfer coefficients are enhanced for low volume fractions when the Reynolds number Re > 7000, in agreement with solid particle nanofluids. However, when the pressure losses are taken into account, we find that the nanofluids studied have a practical efficiency equal to or less than that of the base fluid. The highest heat transfer enhancements were obtained with volume fractions considerably smaller than those for the solid particle nanofluids. Our results indicate that the improved heat transfer is due to enhancement of turbulence in the large Re regime.

Sampo Saarinen; Salla Puupponen; Arttu Meriläinen; Aliakbar Joneidi; Ari Seppälä; Kari Saari; Tapio Ala-Nissila

2015-01-01T23:59:59.000Z

27

J_{E_T}: A Global Jet Finding Algorithm  

E-Print Network [OSTI]

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

Yang Bai; Zhenyu Han; Ran Lu

2014-11-13T23:59:59.000Z

28

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

E-Print Network [OSTI]

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

29

Protostellar Outflow Evolution in Turbulent Environments  

SciTech Connect (OSTI)

The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.

Cunningham, A; Frank, A; Carroll, J; Blackman, E; Quillen, A

2008-04-11T23:59:59.000Z

30

Modified shielding jet model for twin-jet shielding analysis  

E-Print Network [OSTI]

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

Gilbride, Jennifer Frances

2012-06-07T23:59:59.000Z

31

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

E-Print Network [OSTI]

jet. They reported the penetration length and spreading rate of a non-harmonic unsteady jet that the en- trainment rate varied linearly with axial penetration, and the total mass entrainment had a cubic to investigate the transient jet [1­3]. Kouros et al. [4] measured the spreading rate of an unsteady turbulent

Budair, Mohammed Omar

32

Wave Packets and Turbulent Peter Jordan1  

E-Print Network [OSTI]

Wave Packets and Turbulent Jet Noise Peter Jordan1 and Tim Colonius2 1 D´epartement Fluides, California 91125; email: peter.jordan@univ-poitiers.fr, colonius@caltech.edu Annu. Rev. Fluid Mech. 2013. 45

Dabiri, John O.

33

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]

sections . . . . . . . . . . . . . . 59 vi 4.11 Suu(k) at Section 4 centerline (not behind plant stem) . . . . . . . . . 61 4.12 Suu(k) at Section 3 centerline (behind plant stem) . . . . . . . . . . . 63 4.13 Suu(k) at Section 4 radial halfwidth (not... behind plant stem) . . . . . 64 4.14 Suu(k) at Section 4 radial halfwidth (behind plant stem) . . . . . . . 65 B.1 ui Section 1 of free jet and Con guration 1 . . . . . . . . . . . . . . . 82 B.2 ui Section 1 of Con gurations 2 and 3...

Allen, Jon Scott

2013-05-29T23:59:59.000Z

34

Large Eddy Simulations of Jet Flow Interactions Within Rod Bundles  

E-Print Network [OSTI]

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...

Salpeter, Nathaniel O.

2010-07-14T23:59:59.000Z

35

Multiple jet interactions  

E-Print Network [OSTI]

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

Hehr, Roger James

2012-06-07T23:59:59.000Z

36

Jet Observables Without Jet Algorithms  

E-Print Network [OSTI]

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 like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables---jet multiplicity, summed scalar transverse momentum, and missing transverse momentum---have event shape counterparts that are closely correlated with their jet-based cousins. Due to their "local" computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

Daniele Bertolini; Tucker Chan; Jesse Thaler

2013-10-28T23:59:59.000Z

37

Circular polarization in the optical afterglow of GRB 121024A  

E-Print Network [OSTI]

Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet, when measured minutes after the burst, and the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after burst in GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and negligable circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blastwave. Here we report the detection of circularly polarized optical light in the afterglow of GRB 121024A, measured 0.1...

Wiersema, K; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Gotz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; Alighieri, S di Serego; Tagliaferri, G; Vergani, S D; Elliott, J; Farina, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovski, V; Willingale, R

2014-01-01T23:59:59.000Z

38

Circular free-electron laser  

DOE Patents [OSTI]

A high efficiency, free electron laser utilizing a circular relativistic electron beam accelerator and a circular whispering mode optical waveguide for guiding optical energy in a circular path in the circular relativistic electron beam accelerator such that the circular relativistic electron beam and the optical energy are spatially contiguous in a resonant condition for free electron laser operation. Both a betatron and synchrotron are disclosed for use in the present invention. A free electron laser wiggler is disposed around the circular relativistic electron beam accelerator for generating a periodic magnetic field to transform energy from the circular relativistic electron beam to optical energy.

Brau, Charles A. (Los Alamos, NM); Kurnit, Norman A. (Santa Fe, NM); Cooper, Richard K. (Los Alamos, NM)

1984-01-01T23:59:59.000Z

39

Increasing jet entrainment, mixing and spreading  

DOE Patents [OSTI]

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.

Farrington, R.B.

1994-08-16T23:59:59.000Z

40

Plasma turbulence  

SciTech Connect (OSTI)

The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.

Horton, W. [Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies; Hu, G. [Globalstar LP, San Jose, CA (United States)

1998-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

How turbulence enhances coalescence of settling particles with applications to rain in clouds  

Science Journals Connector (OSTI)

...Department of Earth Sciences, University...Mechanical and Aerospace Engineering...The other recent review paper...summarizes recent advances in this area...Ministry of Science and Technology...turbulence. In Advances in turbulence...air jet. In Advances in turbulence...pollution. Science. 287, 1793-1796...

2005-01-01T23:59:59.000Z

42

Astrophysical Jets  

SciTech Connect (OSTI)

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

Madejski, Grzegorz (SLAC) [SLAC

2006-05-01T23:59:59.000Z

43

Stellar jets  

E-Print Network [OSTI]

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.

Thomas J. Maccarone

2008-05-23T23:59:59.000Z

44

Gravitomagnetic jets  

SciTech Connect (OSTI)

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.

Chicone, C.; Mashhoon, B. [Department of Mathematics and Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States); Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States)

2011-03-15T23:59:59.000Z

45

Annual Report 2002 5.2. A fast mercury jet entering a 20 T  

E-Print Network [OSTI]

of the camera system (~ 0.33 mm/pixel). The damping of disrupted jets, simulated with highly turbulent jets disruptions. With increasing field, the tip gets thinner. On injecting a mercury jet into a magnetic field://www.cap.bnl.gov/mumu/studyii/ [2] GHMFL, Annual Report 2001 [3] A. Fabich, High Power Proton Beam Shocks and Magnetohydrodynamics

McDonald, Kirk

46

Zonal Flow as Pattern Formation: Merging Jets and the Ultimate Jet Length Scale  

SciTech Connect (OSTI)

Zonal flows are well known to arise spontaneously out of turbulence. It is shown that for statisti- cally averaged equations of quasigeostrophic turbulence on a beta plane, zonal flows and inhomoge- neous turbulence fit into the framework of pattern formation. There are many implications. First, the zonal flow wavelength is not unique. Indeed, in an idealized, infinite system, any wavelength within a certain continuous band corresponds to a solution. Second, of these wavelengths, only those within a smaller subband are linearly stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets.

Jeffrey B. Parker and John A. Krommes

2013-01-30T23:59:59.000Z

47

Turbulent combustion  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

48

Effects of atmospheric-pressure non-thermal plasma jets on enzyme solutions  

Science Journals Connector (OSTI)

In order to study the wide scope of structural information of biomolecules in the presence of biocompatible cold atmospheric pressure plasma jets (CAPJ), we used circular dichroism (CD) and fluorescence experi...

Pankaj Attri; Pannuru Venkatesu; Nagendra Kaushik…

2012-03-01T23:59:59.000Z

49

OMB Circular A-76 (Revised)  

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

EXECUTIVE OFFICE OF THE PRESIDENT EXECUTIVE OFFICE OF THE PRESIDENT OFFICE OF MANAGEMENT AND BUDGET WASHINGTON, DC 20503 May 29, 2003 CIRCULAR NO. A-76 (REVISED) TO THE HEADS OF EXECUTIVE DEPARTMENTS AND ESTABLISHMENTS SUBJECT: Performance of Commercial Activities 1. Purpose. This circular establishes federal policy for the competition of commercial activities. 2. Supersession. This circular supersedes Office of Management and Budget (OMB) Circular No. A-76 (Revised 1999), August 4, 1983; Circular No. A-76 Revised Supplemental Handbook (Revised 2000), March 1996; Office of Federal Procurement Policy Letter 92-1, "Inherently Governmental Functions," September 23, 1992; and OMB Transmittal Memoranda 1 through 25, Performance of Commercial Activities. 3. Authority. Reorganization Plan No. 2 of 1970 (31 U.S.C. § 1111); Executive Order 11541; the Office

50

Circular chemiresistors for microchemical sensors  

DOE Patents [OSTI]

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.

Ho, Clifford K. (Albuquerque, NM)

2007-03-13T23:59:59.000Z

51

Turbulence-chemistry interactions in reacting flows  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

52

Investigating Jet Mixing Using Electrical Resistance Tomography  

Science Journals Connector (OSTI)

Coaxial jet and side entry mixers are used in a wide range of industries for a variety of processes including precipitation polymerization and neutralization duties. Jet mixers are characterized by short contact times between the fluids and can be operated continuously or semi?batch. Coaxial and side entry jets can be designed in order to deliver rapid turbulent mixing using short sections of pipeline. As the energy required for mixing is provided by the addition stream the process?side pressure drop required for homogeneity is very low. A key design parameter for jet mixers is the mixing length the length of pipe downstream of the injection point required to achieve a given degree of homogeneity. The mixing length can be affected by the addition geometry (for example coaxial or side entry) orifice size and shape operating conditions and material properties. This paper presents the use of Electrical Resistance Tomography (ERT) to monitor jet mixing via the addition of a conductivity tracer through coaxial and side entry jets. Multiple ERT sensors are fitted along the pipe downstream of the jet addition point. The ERT sensors enable real time non?invasive measurement of conductivity within the pipe furnishing approximately 2500 conductivity measurements per ERT sensor when modeled independently in 3D. The effect of secondary (main pipe) flow rate and jet configuration on the nature of the tracer plume evolution and axial mixing is determined using this technique.

D. R. Stephenson; M. Cooke; A. Kowalski; T. A. York

2007-01-01T23:59:59.000Z

53

Nuclear spin circular dichroism  

SciTech Connect (OSTI)

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.

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

2014-04-07T23:59:59.000Z

54

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

E-Print Network [OSTI]

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

Kuzmanovic, Aleksandar

55

Rhines scale and spectra of the -plane turbulence with bottom drag Sergey Danilov1,2  

E-Print Network [OSTI]

,7­10 . The Rhines definition involves, however, the undeter- mined energy content of the flow, which depends and dissipation. Clearly, turbulent flows stabilized by the friction have their energy content, hence rms velocity the jet number and the energy peak of the -plane turbulence for strong . The intermediate cases show

Gurarie, David

56

Direct numerical simulation of turbulent reacting flows  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

57

Jet plume injection and combustion system for internal combustion engines  

DOE Patents [OSTI]

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.

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

1993-01-01T23:59:59.000Z

58

Irregular Magnetic Fields in Interstellar Clouds and Variations in the Observed Circular Polarization of Spectral Lines  

E-Print Network [OSTI]

The strengths of magnetic fields in interstellar gas clouds are obtained through observations of the circular polarization of spectral line radiation. Irregularities in this magnetic field may be present due to turbulence, waves or perhaps other causes, and may play an essential role in the structure and evolution of the gas clouds. To infer information about these irregularities from the observational data, we develop statistical relationships between the rms values of the irregular component of the magnetic field and spatial variations in the circular polarization of the spectral line radiation. The irregularities are characterized in analogy with descriptions of turbulence---by a sum of Fourier waves having a power spectrum with a slope similar to that of Kolmogorov turbulence. For comparison, we also perform computations in which turbulent magnetic and velocity fields from representative MHD simulations by others are utilized. Although the effects of the variations about the mean value of the magnetic field along the path of a ray tend to cancel, a significant residual effect in the polarization of the emergent radiation remains for typical values of the relevant parameters. A map of observed spectra of the 21 cm line toward Orion A is analyzed and the results are compared with our calculations in order to infer the strength of the irregular component of the magnetic field. The rms of the irregular component is found to be comparable in magnitude to the mean magnetic field within the cloud. Hence, the turbulent and Alfven velocities should also be comparable.

W. D. Watson; D. S. Wiebe; R. M. Crutcher

2000-10-13T23:59:59.000Z

59

Center for Turbulence Research Annual Research Briefs 2012  

E-Print Network [OSTI]

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

Wang, Wei

60

NO concentration imaging in turbulent nonpremixed flames  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

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.

62

Inclusive Jets in PHP  

E-Print Network [OSTI]

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

Roloff, Philipp

2013-01-01T23:59:59.000Z

63

Inclusive Jets in PHP  

E-Print Network [OSTI]

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

Philipp Roloff

2013-10-23T23:59:59.000Z

64

Turbulent flow in graphene  

E-Print Network [OSTI]

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.

Kumar S. Gupta; Siddhartha Sen

2009-11-03T23:59:59.000Z

65

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

SciTech Connect (OSTI)

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.

Rutland, Christopher J.

2009-04-26T23:59:59.000Z

66

Circular permutant GFP insertion folding reporters  

SciTech Connect (OSTI)

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.

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

2011-06-14T23:59:59.000Z

67

Circular permutant GFP insertion folding reporters  

SciTech Connect (OSTI)

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.

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

2008-06-24T23:59:59.000Z

68

Circular permutant GFP insertion folding reporters  

DOE Patents [OSTI]

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.

Waldo, Geoffrey S.; Cabantous, Stephanie

2013-04-16T23:59:59.000Z

69

Circular permutant GFP insertion folding reporters  

SciTech Connect (OSTI)

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.

Waldo, Geoffrey S; Cabantous, Stephanie

2013-02-12T23:59:59.000Z

70

Tidal Flow Turbulence Measurements  

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

max quire specification of a turbulence intensity, and it is a metric in the wind energy industry. For acoustic Dop surements, a noise-corrected expression of...

71

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

SciTech Connect (OSTI)

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

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

1990-01-01T23:59:59.000Z

72

Gene synthesis by circular assembly amplification  

E-Print Network [OSTI]

Gene synthesis by circular assembly amplification Duhee Bang & George M Church Here we report the development of a gene-synthesis technology, circular assembly amplification. In this approach, we first error-rich products, thereby substantially improving gene-synthesis quality. We used this method

Church, George M.

73

Decay of swirl in turbulent two phase flow  

E-Print Network [OSTI]

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

Neeley, Patrick Foster

2012-06-07T23:59:59.000Z

74

Date: January 16, 2014 Subject: OMB Omni-Circular  

E-Print Network [OSTI]

) on December 26, 2013. The Omni-Circular consolidates, streamlines and supersedes eight existing Circulars, including Circulars A-21, A-110 and A-133. The new regulations will not take effect until December 26, 2014

Grishok, Alla

75

Policy Flash 2013-37 Federal Acquisition Circular (FAC) 2005...  

Energy Savers [EERE]

37 Federal Acquisition Circular (FAC) 2005-66 Policy Flash 2013-37 Federal Acquisition Circular (FAC) 2005-66 Attached is Policy Flash 2013-37 Federal Acquisition Circular (FAC)...

76

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

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

27 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)...

77

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

DOE Patents [OSTI]

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.

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

2008-03-04T23:59:59.000Z

78

Observations of Edge Turbulence  

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

Edge Turbulence 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 Center *Princeton Plasma Physics Laboratory + MPI for Plasma Physics, EURATOM Assoc., Greifswald, Germany American Physical Society - Div. of Plasma Physics Orlando, FL Nov. 12 - Nov. 16, 2007 APS-2007 (2) Background and Motivation for "Xpt-region" View Strong edge turbulence has been observed in nearly all magnetic confinement devices. Desire predictive capability Most previous measurements made near outboard midplane where the turbulence has the following main features: - generation is ballooning-like (absent at inboard midplane, etc.) - filaments/blobs moves radially outward with some poloidal motion

79

ARM - Measurement - Atmospheric turbulence  

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

turbulence turbulence ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Atmospheric turbulence High frequency velocity fluctuations that lead to turbulent transport of momentum, heat, mositure, and passive scalars, and often expressed in terms of variances and covariances. Categories Atmospheric State, Surface Properties Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments CO2FLX : Carbon Dioxide Flux Measurement Systems ECOR : Eddy Correlation Flux Measurement System

80

Information Content of Turbulence  

E-Print Network [OSTI]

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

Rory Cerbus; Walter Goldburg

2013-07-03T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

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

SciTech Connect (OSTI)

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

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

2009-04-01T23:59:59.000Z

82

The turbulent structure of the jet in cross-flow  

E-Print Network [OSTI]

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

Lanitis, Nicolas

2014-04-08T23:59:59.000Z

83

Spectroscopy 16 (2002) 121125 121 Synchrotron radiation circular dichroism  

E-Print Network [OSTI]

undamaged even after long periods of exposure in the Synchroton Radiation Circular Dichroism (SRCD) beam [2

Wallace, Bonnie Ann

84

A spray-suppression model for turbulent combustion  

SciTech Connect (OSTI)

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.

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

2000-02-14T23:59:59.000Z

85

Jets from accretion discs  

Science Journals Connector (OSTI)

...been implicated in jet collimation. A particularly instruc...prototypical disc/jet system HH 30 (Burrows et al...some form of intrinsic collimation, since external density...of intrinsic magnetic collimation. There now exist measurements...from the most embedded systems, the class zero objects...

2000-01-01T23:59:59.000Z

86

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

E-Print Network [OSTI]

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...

Sposato, Christina F

2012-06-07T23:59:59.000Z

87

Turbulence Structure and Wall Signature in Hypersonic Turbulent Boundary Layer  

E-Print Network [OSTI]

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

Martín, Pino

88

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

E-Print Network [OSTI]

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

R. S. Sutherland; G. V. Bicknell

2007-07-25T23:59:59.000Z

89

Federal Acquisition Circular 2005-60  

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

Circular 2005-60 Circular 2005-60 SUMMARY: This document summarizes the Federal Acquisition Regulation (FAR) rules agreed to by the Civilian Agency Acquisition Council and the Defense Acquisition Regulations Council (Councils) in this Federal Acquisition Circular (FAC) 2005-60. Item Subject FAR Case I Reporting Executive Compensation and First-Tier Subcontract Awards 2008-039 II Payments Under Time-and- Materials and Labor-Hour Contracts 2011-003 III Extension of Sunset Date for Protests of Task and Delivery Orders 2012-007 IV DARPA-New Mexico Tax Agreement 2012-019 V Clarification of Standards for Computer Generation of Forms 2011-022 VI Technical Amendments Item I Reporting Executive Compensation and First-Tier Subcontract Awards (FAR Case

90

OMB Circular A-123, Appendix B  

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

T H E D I R E C T O R January 15, 2009 CIRCULAR NO. A-123, Appendix B Revised TO THE HEADS OF EXECUTIVE DEPARTMENTS AND ESTABLISHMENTS SUBJECT: Improving the Management of Government Charge Card Programs Appendix B of OMB Circular A-123 prescribes policies and procedures to agencies regarding how to maintain internal controls that reduce the risk of fraud, waste, and error in government charge card programs. This revision responds to recommendations made by the Government Accountability Office (GAO) regarding the Federal purchase card program as well as agency comments and suggestions made by Agency/Organization Program Coordinators. These revisions replace and rescind all previously issued OMB Circular A-123 Appendix B policy dated February 2006 and August 2005. Significant updates to Appendix B are as follows:

91

ON THE ORIGIN OF INTERGRANULAR JETS  

SciTech Connect (OSTI)

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

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

2011-08-01T23:59:59.000Z

92

EPISODIC JETS AS THE CENTRAL ENGINE OF GAMMA-RAY BURSTS  

SciTech Connect (OSTI)

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.

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

2012-09-20T23:59:59.000Z

93

turbulence | OpenEI  

Open Energy Info (EERE)

turbulence turbulence Dataset Summary Description This raw data reflects readings from instruments mounted on or near a 82 meter meteorological tower located at the National Wind Technology Center (NWTC), approximately 5 miles south of Boulder, CO (specifically: 39.9107 N, 105.2348 W, datum WGS84). Source NREL Date Released Unknown Date Updated Unknown Keywords DOE irradiance NREL NWTC temperature turbulence wind wind direction wind speed Data text/plain icon Raw data (txt, 82 KiB) application/vnd.openxmlformats-officedocument.spreadsheetml.sheet icon Raw data field descriptions (xlsx, 52.5 KiB) Quality Metrics Level of Review Some Review Comment Data have not been reviewed for accuracy or completeness; disclaimer available (http://www.nrel.gov/disclaimer.html). Temporal and Spatial Coverage

94

Angular Scaling In Jets  

SciTech Connect (OSTI)

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.

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

2012-02-17T23:59:59.000Z

95

Federal Acquisition Circular 2005-36  

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

Federal Acquisition Circular 2005-36 Federal Acquisition Circular 2005-36 Item Subject FAR case I.............. Federal Technical Data Solution (FedTeDS) 2008-038 II............. Fair Labor Standards Act and Service Contract 2007-021 Act Price Adjustment Clauses. III............ New Designated Country-Taiwan 2009-014 IV............. Prohibition on Restricted Business Operations 2008-004 in Sudan and Imports from Burma. V.............. List of Approved Attorneys, Abstractors, and 2006-013 Title Companies. VI............. Cost Accounting Standards (CAS) 2007-002 Administration and Associated Federal Acquisition Regulation Clauses. VII............ Technical Amendments

96

Jet and Photon Physics  

E-Print Network [OSTI]

Jet production in proton-proton collisions is one of the main phenomenological predictions of QCD. The ATLAS and CMS Collaborations have performed measurements of several jet observables at the LHC and compared their results to theoretical predictions and event generators. Useful physics input for the determination of the parton distribution functions and the strong coupling constant is provided. Photon production measurements represent another important test of QCD and show strong sensitivity to higher-order corrections.

Peruzzi, Marco

2014-01-01T23:59:59.000Z

97

Jet and photon physics  

E-Print Network [OSTI]

Jet production in proton-proton collisions is one of the main phenomenological predictions of QCD. The ATLAS and CMS Collaborations have performed measurements of several jet observables at the LHC and compared their results to theoretical predictions and event generators. Useful physics input for the determination of the parton distribution functions and the strong coupling constant is provided. Photon production measurements represent another important test of QCD and show strong sensitivity to higher-order corrections.

Marco Peruzzi; for the ATLAS; CMS Collaborations

2014-09-30T23:59:59.000Z

98

Characterization of Relativistic MHD Turbulence  

E-Print Network [OSTI]

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.

Garrison, David

2015-01-01T23:59:59.000Z

99

On the properties of Circular-Beams  

E-Print Network [OSTI]

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

Giuseppe Vallone

2015-01-28T23:59:59.000Z

100

A commotion over turbulence  

Science Journals Connector (OSTI)

... calculations) of dimensionless parameters of the reactor setup9. This has led to the IFS/PPPL model, named after the main institutions involved in its development. The basis for this ... other components besides the turbulence-induced diffusivity. Dorland and Kotschen-reuther have combined the IFS/PPPL diffusivity model with an assumed prescription for the density evolution and the boundary temperatures, ...

Benjamin A. Carreras

1997-01-23T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Cleaning of soft-solid soil layers on vertical and horizontal surfaces by stationary coherent impinging liquid jets  

E-Print Network [OSTI]

), Tank cleaning technology: Innovative application to improve clean-in-place (CIP), EHEDG Yearbook 2011/2012, 26-30. Kate, R. P., Das, P. K. and Chakraborty, S. (2007) Hydraulic jumps due to oblique impingement of circular liquid jets on a flat...

Wilson, D. I.; Atkinson, P.; Köhler, H.; Mauermann, M.; Stoye, H.; Suddaby, K.; Wang, T.; Davidson, J. F.; Majschak, J. -P.

2014-02-03T23:59:59.000Z

102

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

Energy Savers [EERE]

4-38 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...

103

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...

104

Policy Flash 2014-11 Federal Acquisition Circular (FAC) 2005...  

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

1 Federal Acquisition Circular (FAC) 2005-71 Policy Flash 2014-11 Federal Acquisition Circular (FAC) 2005-71 Questions concerning this policy flash should be directed to Barbara...

105

NOAA Technical Report NMFS Circular 450 The Utility of Developmental  

E-Print Network [OSTI]

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

106

Lines of Circular Polarization in Electromagnetic Wave Fields  

Science Journals Connector (OSTI)

8 October 1983 research-article Lines of Circular Polarization in Electromagnetic Wave Fields J...free space possesses, in general, two families of singular lines ( lines) on which the transverse field is circularly polarized. The...

1983-01-01T23:59:59.000Z

107

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

E-Print Network [OSTI]

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

Sutherland, R S

2007-01-01T23:59:59.000Z

108

GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM  

SciTech Connect (OSTI)

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.

Cho, Jungyeon; Yoo, Hyunju, E-mail: jcho@cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2012-11-10T23:59:59.000Z

109

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

E-Print Network [OSTI]

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

California at San Diego, University of

110

Modeling Turbulent Flow  

National Nuclear Security Administration (NNSA)

Turbulent Turbulent Flow with Implicit LES L.G. Margolin 1 Proceedings of the Joint Russian-American Five Laboratory Conference on Computational Mathematics/Physics 19-23 June, 2005 Vienna, Austria 1 Applied Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, len@lanl.gov 1 Abstract Implicit large eddy simulation (ILES) is a methodology for modeling high Reynolds' num- ber flows that combines computational efficiency and ease of implementation with predictive calculations and flexible application. Although ILES has been used for more than fifteen years, it is only recently that significant effort has gone into providing a physical rationale that speaks to its capabilities and its limitations. In this talk, we will present new theoret- ical results aimed toward building a justification and discuss some remaining gaps in our understanding and our practical

111

Circular zig-zag scan video format  

DOE Patents [OSTI]

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.

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

1992-01-01T23:59:59.000Z

112

Top Jets at the LHC  

E-Print Network [OSTI]

Physics Signatures at the LHC,” talk presented at the 2007Top Jets at the LHC Leandro G. Almeida, Seung J. Lee, GiladSEPT-DPP Top Jets at the LHC Leandro G. Almeida a , Seung J.

Almeida, L.G.

2009-01-01T23:59:59.000Z

113

Transition to turbulence in ferrofluids  

E-Print Network [OSTI]

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

Altmeyer, Sebastian; Lai, Ying-Cheng

2015-01-01T23:59:59.000Z

114

Organic vapor jet printing system  

SciTech Connect (OSTI)

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

Forrest, Stephen R

2012-10-23T23:59:59.000Z

115

Quantum ghost imaging through turbulence  

SciTech Connect (OSTI)

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 the entangled photon source from the ghost-imaging central image plane, we are able to dramatically increase the ghost-image quality. When imaging a test pattern through turbulence, this method increases the imaged pattern visibility from V=0.15{+-}0.04 to 0.42{+-}0.04.

Dixon, P. Ben; Howland, Gregory A.; Howell, John C. [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Chan, Kam Wai Clifford [Rochester Optical Manufacturing Company, Rochester, New York 14606 (United States); O'Sullivan-Hale, Colin; Rodenburg, Brandon [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Hardy, Nicholas D.; Shapiro, Jeffrey H. [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Simon, D. S.; Sergienko, A. V. [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Boyd, R. W. [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

2011-05-15T23:59:59.000Z

116

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

E-Print Network [OSTI]

) 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... The dimensionless temperature gradient at the interface of the tube Qf is defined by the following equation; Q=qr/kt ? ? ? ? ? H f f o f fe Q=qr/k(t -t) ? ? -T f f o f fe w (15) from Eq. (14) 2- j. L. 'P. ( & ) j+ Pmi =I 2=1 &zH e j Anal sis of Ener E uation...

Lin, Yie-Kuang

2012-06-07T23:59:59.000Z

117

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

E-Print Network [OSTI]

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...

Lakshmipathy, Sunil

2006-04-12T23:59:59.000Z

118

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

E-Print Network [OSTI]

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

Reyes, Dasia Ann

2009-05-15T23:59:59.000Z

119

Filtering Turbulent Sparsely Observed Geophysical Flows  

Science Journals Connector (OSTI)

Filtering sparsely turbulent signals from nature is a central problem of contemporary data assimilation. Here, sparsely observed turbulent signals from nature are generated by solutions of two-layer quasigeostrophic models with turbulent cascades ...

John Harlim; Andrew J. Majda

2010-04-01T23:59:59.000Z

120

Revised OMB Circular A-76 (Revised November 14, 2002)  

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

OMB Circular A-76 Revision Comments OMB Circular A-76 Revision Comments DRAFT OMB CIRCULAR A-76 (NOVEMBER 14, 2002) REVIEW COMMENTS AND RECOMMENDATIONS GENERAL COMMENTS: The Department of Energy (DOE) supports the overarching goal of OMB Circular A-76 that agencies should obtain "the best deal to the Taxpayer." We also support revisions to the Circular that "Keep the Process Moving" with the end result being: Faster/Cheaper Competitions; Improved Performance and Measures; Enhanced/Expanded Competition; Fairness; Realizing Significant Savings; and the Redirection of Resources to Mission Critical Requirements. Upon review of the draft Circular, the Department believes the proposed changes to Circular reflect a general improvement over the current version. The Department does, however, have

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Global simulations of magnetorotational turbulence – II. Turbulent energetics  

Science Journals Connector (OSTI)

......Importantly, as we are using an ideal MHD simulation, this shows that...construct a simplified energy flow diagram, which is shown in Fig...the heart of self-sustaining MHD turbulence in accretion discs. Figure 14. Energy flow diagram for turbulence in a global disc......

E. R. Parkin

2014-01-01T23:59:59.000Z

122

Gasoline Jet Fuels  

E-Print Network [OSTI]

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

Kemner, Ken

123

Jets from accretion discs  

Science Journals Connector (OSTI)

...associ- ation with relativistic processes and accretion discs in the...laboratory in which to study these processes on shorter time-scales in...astrophysics. Proc. 12th Kingston Mtg (ed. D. A. Clarke & M...astrophysical jets. II. Dynamical processes in the accretion of magnetized...

2000-01-01T23:59:59.000Z

124

Downhole jet pump  

SciTech Connect (OSTI)

This patient describes a well equipped to produce oil at the surface from a subterranean formation including: a casing string cemented in a well bore penetrating the earth to a depth below the formation, the casing string comprising perforations extending through the casing string into communication with the formation; a packer sealed against the interior of the casing string above the formation; a tubing string inside the casing string and providing therewith an annulus, the tubing string being connected to the packer and extending upwardly to the surface, the tubing string and annulus providing a first upward path to the surface and a second downward fluid path from the surface; and a jet pump assembly including a jet pump below the packer comprising a body having an upper end, an outlet in communicating with the first fluid path, a nozzle section having a suction inlet below the packer and a power fluid inlet, means providing communication between the second fluid path and the nozzle section for delivering power fluid to the power fluid inlet and means connecting the upper jet pump body end to the tubing string comprising as J-slot receptacle secured to the upper jet pump body end having a J-slot therein, a tubular member connected with and communicating with the tubing string and having a J-slot pin on the lower end thereof removably received in the J-slot and means sealing between the J-slot receptacle and J-slot pin.

Weeks, B.R.

1988-12-13T23:59:59.000Z

125

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...

126

Experimental Study of Circular Laminar Confined Jets at Low Reynolds Numbers  

E-Print Network [OSTI]

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

Diggavi, Suhas

127

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

E-Print Network [OSTI]

. . Heat transfer and Flutd flow results ? Counter flow . 32 64 CONCLUSIONS . 101 REFERENCES . 104 APPENDIX A. APPENDIX B APPENDIX C LIST OF FIGURES FIGURE 1 Detailed Schematic of the Test Section with the Flow Loop for 81. 27cm Inner pipe... with Parallel Flow. . 2 Schematic Diagram showing the arrangement of the mner pipes with different diameters with the copper segments. 3 Schematic of the test section showmg the two different flow arrangements (Parallel Flow and Counter Flow) . Page 12 14...

Mhetras, Shantanu Prakash

2012-06-07T23:59:59.000Z

128

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

SciTech Connect (OSTI)

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

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

2007-10-15T23:59:59.000Z

129

Turbulent Magnetic Reconnection Near a  

E-Print Network [OSTI]

Turbulent Magnetic Reconnection Near a 3D Magnetic Null C. S. Ng Space Science Center Institute for the Study of Earth, Oceans, and Space University of New Hampshire, Durham, NH 03824 #12;Turbulent Magnetic Reconnection Near a 3D Magnetic Null C. S. Ng, chung-sang.ng@unh.edu, Space Science Center, Institute

Ng, Chung-Sang

130

Advances in compressible turbulent mixing  

SciTech Connect (OSTI)

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.

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

1992-01-01T23:59:59.000Z

131

Circular zig-zag scan video format  

DOE Patents [OSTI]

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.

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

1992-06-09T23:59:59.000Z

132

A Family of Circular Bargmann Transforms  

E-Print Network [OSTI]

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.

Zouhair Mouayn

2011-05-24T23:59:59.000Z

133

Residual turbulence from velocity shear stabilized interchange instabilities  

SciTech Connect (OSTI)

The stabilizing effect of velocity shear on the macroscopic, broad bandwidth, ideal interchange instability is studied in linear and nonlinear regimes. A 2D dissipative magnetohydrodynamic (MHD) code is employed to simulate the system. For a given flow shear, V Prime , linear growth rates are shown to be suppressed to below the shear-free level at both the small and large wavelengths. With increasing V Prime , the unstable band in wavenumber-space shrinks so that the peak growth results for modes that correspond to relatively high wavenumbers, on the scale of the density gradient. In the nonlinear turbulent steady state, a similar turbulent spectrum obtains, and the convection cells are roughly circular. In addition, the density fluctuation level and the degree of flattening of the initial inverted density profile are found to decrease as V Prime increases; in fact, unstable modes are almost completely stabilized and the density profile reverts to laminar when V Prime is a few times the classic interchange growth rate. Moreover, the turbulent particle flux diminishes with increasing velocity shear such that all the flux is carried by the classical diffusive flux in the asymptotic limit. The simulations are compared with measurements of magnetic fluctuations from the Maryland Centrifugal Experiment, MCX, which investigated interchange modes in the presence of velocity shear. The experimental spectral data, taken in the plasma edge, are in general agreement with the numerical data obtained in higher viscosity simulations for which the level of viscosity is chosen consistent with MCX Reynolds numbers at the edge. In particular, the residual turbulence in both cases is dominated by elongated convection cells. Finally, concomitant Kelvin-Helmholtz instabilities in the system are also examined. Complete stability to interchanges is obtained only in the parameter space wherein the generalized Rayleigh inflexion theorem is satisfied.

Hung, C. P.; Hassam, A. B. [University of Maryland at College Park, College Park, Maryland 20742 (United States)

2013-01-15T23:59:59.000Z

134

V+jets production at the CMS  

E-Print Network [OSTI]

Measurements of Vector Boson production in association with jets are presented, using p-p collision data at sqrt{s} = 7 TeV. The measurements presented include Z + jets azimuthal correlations, event shapes, vector boson + jets differential cross section measurements, hard double-parton scattering using W + jets events and electroweak Z + forward - backward jet production.

B. Bilin; for the CMS Collaboration

2014-10-22T23:59:59.000Z

135

The Effect of Circularly Polarized Light on the Photosynthesis and ...  

Science Journals Connector (OSTI)

The net photosynthesis and chlorophyll a synthesis of certain marine algae show a gra- dation in response to various types of polarized light. Right circularly.

1999-12-14T23:59:59.000Z

136

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

E-Print Network [OSTI]

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.

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

2002-07-02T23:59:59.000Z

137

Memory effects in turbulent transport  

E-Print Network [OSTI]

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.

Alexander Hubbard; Axel Brandenburg

2008-11-17T23:59:59.000Z

138

Compound cooling flow turbulator for turbine component  

DOE Patents [OSTI]

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.

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

2014-11-25T23:59:59.000Z

139

Information theoretical characterization of turbulence  

Science Journals Connector (OSTI)

A method of describing turbulence in terms of dynamical connectivity in the wave-number space is proposed. The connectivity is quantified by the information theoretical quantities, i.e., mutual information and cross information flow rate. This method is applied to the analysis of two simple examples of turbulence in one spatial dimension. Although the examples have quite different physical origins, the information structures of the wave-number space turn out to be quite similar: The wave-number space consists of several regions generating information in different ways, and how information flows between these regions reflects the dynamical structure of turbulence.

K. Ikeda and K. Matsumoto

1989-05-08T23:59:59.000Z

140

BNL experiment with gas jet  

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

project: Study of Hot Electron Transport and Subsequent Ion Acceleration using Overdense Gas Jet Target and Ultrafast TW CO2 Laser System Vitaly Yakimenko, Igor Pogorelsky ATF,...

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Jet Charge at the LHC  

Science Journals Connector (OSTI)

Knowing the charge of the parton initiating a light-quark jet could be extremely useful both for testing aspects of the standard model and for characterizing potential beyond-the-standard-model signals. We show that despite the complications of hadronization and out-of-jet radiation such as pileup, a weighted sum of the charges of a jet’s constituents can be used at the LHC to distinguish among jets with different charges. Potential applications include measuring electroweak quantum numbers of hadronically decaying resonances or supersymmetric particles, as well as standard model tests, such as jet charge in dijet events or in hadronically decaying W bosons in tt¯ events. We develop a systematically improvable method to calculate moments of these charge distributions by combining multihadron fragmentation functions with perturbative jet functions and pertubative evolution equations. We show that the dependence on energy and jet size for the average and width of the jet charge can be calculated despite the large experimental uncertainty on fragmentation functions. These calculations can provide a validation tool for data independent of Monte Carlo fragmentation models.

David Krohn; Matthew D. Schwartz; Tongyan Lin; Wouter J. Waalewijn

2013-05-21T23:59:59.000Z

142

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

E-Print Network [OSTI]

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

Gerbi, Gregory Peter

2008-01-01T23:59:59.000Z

143

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 Noncompetitive Contracts in "Unusual and Compelling Urgency" Circumstances III. GAO Access to Contractor Employees IV. Use of Commercial Services Item Authority V. Limitations on Pass-Through Charges VI. Award Fee Language Revision VII. National Response Framework VIII. Technical Amendments SUPPLEMENTARY INFORMATION: Summaries for each FAR rule follow. Item I-Registry of Disaster Response Contractors (FAR Case 2008-035) This interim rule amends the FAR at parts 2, 4, 7, 10, 13, 18, 26, and 52 to implement the Registry of Disaster Response Contractors provision, section 697 of the Department of

144

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 Date: June 18, 2004 What is the purpose of this FAR Case? This interim rule amends the FAR providing authority to treat perfonnance-based contract or task orders for services as commercial items if specific conditions are met. It also requires agencies to report on perfonnance-based contracts or task orders awarded using this authority. This rulemaking affects FAR Parts 2, Definitions, 12, Acquisition of Commercial Items, 37, Service Contracting, and 52, Solicitation Provisions and Contract Clauses. ~ Provides that performance-based contracts and task orders for services with an estimated value not to exceed $25,000,000, be treated as

145

Federal Acquisition Regulation; Federal Acquisition Circular  

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

0 0 Federal Acquisition Circular (FAC) 2005-40 Federal Register /Vol. 75, No. 55 /Tuesday, March 23, 2010 /page 14059 A summary for the FAR rule follows. Federal Awardee Performance and Integrity Information System (FAPIIS) (FAR case 2008-027) Effective Date: April 22, 2010. This final rule amends the FAR to implement section 872 of the Duncan Hunter National Defense Authorization Act for Fiscal Year 2009. Section 872 requires the establishment of a data system, Federal Awardee Performance and Integrity Information System (FAPIIS), containing specific information on the integrity and performance of covered Federal agency contractors and grantees. FAPIIS is available for use in award decisions at www.ppirs.gov. Government input to FAPIIS is accomplished at www.cpars.csd.disa.mil.

146

Plasma jets key to enduring solar mystery  

Science Journals Connector (OSTI)

... a few million degrees? The answer, researchers say, might lie in hot jets of plasma erupting from the Sun's surface. ... erupting from the Sun's surface. Plasma jets have also been considered as a possible heating mechanism. These jets are known ...

Jon Cartwright

2011-01-06T23:59:59.000Z

147

The Dynamics of Baroclinic Zonal Jets  

Science Journals Connector (OSTI)

Multiple alternating zonal jets are a ubiquitous feature of planetary atmospheres and oceans. However, most studies to date have focused on the special case of barotropic jets. Here we investigate the dynamics of freely evolving baroclinic jets, ...

Paul D. Williams; Christopher W. Kelsall

148

Simplified expansions for radiation from a baffled circular piston  

E-Print Network [OSTI]

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

Mast, T. Douglas

149

Direct Numerical Simulation of Autoiginition of a Hydrogen Jet in a  

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

Direct Numerical Simulation of Autoiginition of a Hydrogen Jet in a Direct Numerical Simulation of Autoiginition of a Hydrogen Jet in a Preheated Cross Flow Submitted by mkaczmar on June 4, 2013 - 13:52 Authors: Abdilghanie, A., Frouzakis, C.E., Fischer, P Autoignition of a nitrogen-diluted hydrogen mixture issuing from a round nozzle into a cross-flowing turbulent stream of preheated air flowing in a channel at a friction Reynolds number Re = 180 is inves- tigated via 3-D direct numerical simulations (DNS) at two crossflow stream temperatures (930 and 950 K). Three-dimensional visualizations of the JICF reveal a complicated flow structure characterized by a variety of coherent vortical structures resulting from the boundary layers near the walls and evolving from the jet instabilities. The mean pressure field set up by the flow

150

Sustainable Alternative Jet Fuels | Department of Energy  

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

Sustainable Alternative Jet Fuels Sustainable Alternative Jet Fuels Nate Brown, Federal Aviation Administration, presentation at the Industry Roundtable on Update on ASTM Approval....

151

Circularization of Tidally Disrupted Stars around Spinning Supermassive Black Holes  

E-Print Network [OSTI]

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...

Hayasaki, Kimitake; Loeb, Abraham

2015-01-01T23:59:59.000Z

152

Mercury Jet Studies Tristan Davenne  

E-Print Network [OSTI]

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

McDonald, Kirk

153

OPENING ANGLES OF COLLAPSAR JETS  

SciTech Connect (OSTI)

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.

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

2013-11-10T23:59:59.000Z

154

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

SciTech Connect (OSTI)

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

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

2006-07-15T23:59:59.000Z

155

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]

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 regionÃ?cient, nonpolluting diesel engine. Many parameters such as the nuzzle shape, the velocity and the turbulence

New York at Stoney Brook, State University of

156

Accepted, Nuclear Fusion, 1999 Turbulent Transport and Turbulence in Radiative I-Mode Plasmas in  

E-Print Network [OSTI]

Accepted, Nuclear Fusion, 1999 Turbulent Transport and Turbulence in Radiative I-Mode Plasmas of Physics University of Alberta Edmonton, Alberta Canada, T6G 2J1 1/4/00 17:25 PM #12;Accepted, Nuclear Fusion, 1999 1 Abstract First measurements of turbulence levels and turbulence-induced transport

California at San Diego, University of

157

Assessment of TurbulenceChemistry Interaction in Hypersonic Turbulent Boundary Layers  

E-Print Network [OSTI]

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

Martín, Pino

158

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

E-Print Network [OSTI]

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

Martín, Pino

159

Micromachined chemical jet dispenser  

DOE Patents [OSTI]

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.

Swierkowski, Steve P. (Livermore, CA)

1999-03-02T23:59:59.000Z

160

Selected problems in turbulence theory and modeling  

E-Print Network [OSTI]

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

Jeong, Eun-Hwan

2004-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Usage of turbulence for superresolved imaging  

Science Journals Connector (OSTI)

We have used the turbulent flow of hot air to improve the diffraction limits of resolution in an imaging system. A time-multiplexing approach was applied and used the turbulent flow...

Zalevsky, Zeev; Rozental, Shay; Meller, Moshe

2007-01-01T23:59:59.000Z

162

Flight–crash events in turbulence  

Science Journals Connector (OSTI)

...Institute of Science, Rehovot 76100...Mechanical and Aerospace Engineering, Cornell...14). The recent advances in our ability...turbulent flow . Science 311 ( 5762 ): 835...turbulence: recent results...Cooperation in Science and Technology...

Haitao Xu; Alain Pumir; Gregory Falkovich; Eberhard Bodenschatz; Michael Shats; Hua Xia; Nicolas Francois; Guido Boffetta

2014-01-01T23:59:59.000Z

163

Effects of Atmospheric Turbulence on Ballistic Testing  

Science Journals Connector (OSTI)

The effects of atmospheric turbulence on munition target scatter are determined from numerical simulations of ballistic trajectories through many realizations of realistic simulated turbulent wind fields. A technique is evaluated for correcting ...

Rod Frehlich; Robert Sharman; Charles Clough; Michael Padovani; Kelly Fling; Ward Boughers; W. Scott Walton

2008-05-01T23:59:59.000Z

164

Holographic Vortex Liquids and Superfluid Turbulence  

Science Journals Connector (OSTI)

...of Kelvin waves flowing along vortex strings in 3D quantum turbulence...theory correlators from non-critical string theory . Phys. Lett. B...S. , Emergence of turbulence in an oscillating Bose-Einstein condensate . Phys. Rev...

Paul M. Chesler; Hong Liu; Allan Adams

2013-07-26T23:59:59.000Z

165

Jets in heavy ion collisions with ATLAS  

E-Print Network [OSTI]

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

Martin Spousta; for the ATLAS Collaboration

2012-11-14T23:59:59.000Z

166

Stimulated Neutrino Transformation Through Turbulence  

E-Print Network [OSTI]

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

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

2014-04-15T23:59:59.000Z

167

Latest jet results from the Tevatron  

SciTech Connect (OSTI)

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

Price, Darren D.

2010-05-01T23:59:59.000Z

168

IAEA Information Circular 225 Revision 5: Fact Sheet | National Nuclear  

National Nuclear Security Administration (NNSA)

IAEA Information Circular 225 Revision 5: Fact Sheet | National Nuclear IAEA Information Circular 225 Revision 5: Fact Sheet | National Nuclear Security Administration Our Mission Managing the Stockpile Preventing Proliferation Powering the Nuclear Navy Emergency Response Recapitalizing Our Infrastructure Continuing Management Reform Countering Nuclear Terrorism About Us Our Programs Our History Who We Are Our Leadership Our Locations Budget Our Operations Media Room Congressional Testimony Fact Sheets Newsletters Press Releases Speeches Events Social Media Video Gallery Photo Gallery NNSA Archive Federal Employment Apply for Our Jobs Our Jobs Working at NNSA Blog Home > Media Room > Fact Sheets > IAEA Information Circular 225 Revision 5: Fact Sheet Fact Sheet IAEA Information Circular 225 Revision 5: Fact Sheet Mar 23, 2012 The Department of Energy's National Nuclear Security Administration

169

Technical Standards, OMB Circular A-119 - May 14, 1998 | Department...  

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

in order to make the terminology of the Circular consistent with the National Technology Transfer and Advancement Act of 1995, to issue guidance to the agencies on making their...

170

turbulent heat International Journal of Numerical  

E-Print Network [OSTI]

Enhanced turbulent heat transfer 47 International Journal of Numerical Methods for Heat & Fluid, Hsinchu,Taiwan Keywords Heat transfer, Fluids, Flow, Turbulence, Numerical methods Abstract This study evaluates low Reynolds number models of turbulence for numerical computations on the heat transfer and fluid

Lin, Wen-Wei

171

TURBULENCE IN SUPERSONIC AND HYPERSONIC BOUNDARY LAYERS  

E-Print Network [OSTI]

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

Martín, Pino

172

Scour around a circular pile due to oscillatory wave motion  

E-Print Network [OSTI]

SCOUR AROUND A CIRCULAR PILE DUE TO OSCILLATORY WAVE MOTION A Thesis by DONALD RAYMOND WELLS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE January... 1970 Major Subject: Civil Engineering SCOUR AROUND A CIRCULAR PILE DUE TO OSCILLATORY WAVE MOTION A Thesis by DONALD RAYMOND WELLS Approved as to style and content by: hairman of Committee) (Head of Department) ember) . (Member) (Member...

Wells, Donald Raymond

2012-06-07T23:59:59.000Z

173

Electronic Circular Dichroism of Proteins from First-Principles Calculations  

Science Journals Connector (OSTI)

Electronic Circular Dichroism of Proteins from First-Principles Calculations ... The circular dichroism (CD) spectra of 47 proteins in the far-ultraviolet have been calculated from first principles, using a parameter set derived from ab initio calculations on N-methylacetamide. ... An important aspect of calculating protein CD spectra is the accurate parametrization of the ground and excited electronic states of the amide chromophore. ...

Jonathan D. Hirst; Karl Colella; Andrew T. B. Gilbert

2003-09-30T23:59:59.000Z

174

Magnetohydrodynamic Production of Relativistic Jets  

Science Journals Connector (OSTI)

...of the properties of the MHD model. The diagram shows flow velocity...jet. Figure 3 Schematic diagram depicting the MHD acceleration and...of the properties of the MHD model. The diagram shows flow velocity...

David L. Meier; Shinji Koide; Yutaka Uchida

2001-01-05T23:59:59.000Z

175

Strategic Technology JET PROPULSION LABORATORY  

E-Print Network [OSTI]

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

Waliser, Duane E.

176

Numerical Simulations of Bouncing Jets  

E-Print Network [OSTI]

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.

Bonito, Andrea; Lee, Sanghyun

2015-01-01T23:59:59.000Z

177

Perpendicular ion acceleration in whistler turbulence  

SciTech Connect (OSTI)

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

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

2014-04-15T23:59:59.000Z

178

Analysis of a Low-level Coastal Jet off the Western Coast of Norway  

Science Journals Connector (OSTI)

Abstract Offshore wind installations depend strongly on an improved knowledge of the atmospheric and ocean conditions affecting the marine atmospheric boundary layer (MABL). In particular the better understanding of atmospheric phenomena that are related to extreme atmospheric and sea state conditions e.g. high levels of wind speed, wind shear, waves and turbulence, is crucially important for offshore applications. This study investigates a low level coastal jet off the Western coast of Norway on 20 March 2011, using both in situ data and model results. The analysis is focused on parameters that are relevant to wind energy such as wind speed, turbulence intensity and wind shear. The jet is characterized by high wind speeds, moderate turbulence intensity and significant high wind shear. Furthermore, the structure and the dynamical characteristics of the low level coastal flow are investigated from the model results. The results show a maximum wind speed, greater than 30 m/s, between 500 to 800 m height above the sea level and at 15-20 km distance from the coast.

Konstantinos Christakos; George Varlas; Joachim Reuder; Petros Katsafados; Anastasios Papadopoulos

2014-01-01T23:59:59.000Z

179

Wave turbulence in quantum fluids  

Science Journals Connector (OSTI)

...range, as shown by the inset bifurcation diagram. Fig. 2. Second sound turbulence...metastable state. (Inset) Bifurcation diagram showing regions of stability (unshaded) and...159 . 9 Ryutova M Tarbell T ( 2003 ) MHD shocks and the origin of the solar transition...

German V. Kolmakov; Peter Vaughan Elsmere McClintock; Sergey V. Nazarenko

2014-01-01T23:59:59.000Z

180

Turbulent phenomena in protein folding  

Science Journals Connector (OSTI)

Protein folding and hydrodynamic turbulence are two long-standing challenges, in molecular biophysics and fluid dynamics, respectively. The theories of these phenomena have been developed independently and used different formalisms. Here we show that the protein folding flows can be surprisingly similar to turbulent fluid flows. Studying a benchmark model protein (an SH3 domain), we have found that the flows for the slow folding trajectories of the protein, in which a partly formed N- and C-terminal ? sheet hinders the RT loop from attaching to the protein core, have many properties of turbulent flows of a fluid. The flows are analyzed in a three-dimensional (3D) space of collective variables, which are the numbers of native contacts between the terminal ? strands, between the RT loop and the protein core, and the rest of the native contacts. We have found that the flows have fractal nature and are filled with 3D eddies; the latter contain strange attractors, at which the tracer flow paths behave as saddle trajectories. Two regions of the space increment have been observed, in which the flux variations are self-similar with the scaling exponent h=1/3, in surprising agreement with the Kolmogorov inertial range theory of turbulence. In one region, the cascade of protein rearrangements is directed from larger to smaller scales (net folding), and in the other, it is oppositely directed (net unfolding). Folding flows for the fast trajectories are essentially “laminar” and do not have the property of self-similarity. Based on the results of our study, we infer, and support this inference by simulations, that the origin of the similarity between the protein folding and turbulent motion of a fluid is in a cascade mechanism of structural transformations in the systems that underlies these phenomena.

Igor V. Kalgin and Sergei F. Chekmarev

2011-01-31T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

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

E-Print Network [OSTI]

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

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

2015-01-01T23:59:59.000Z

182

Three-dimensional simulations of cellular non-premixed jet flames  

SciTech Connect (OSTI)

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)

Valaer, A.L.; Frouzakis, C.E.; Boulouchos, K. [Aerothermochemistry and Combustion System Laboratory, Swiss Federal Institute of Technology, CH-8092 Zurich (Switzerland); Papas, P. [Division of Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Tomboulides, A.G. [Department of Engineering and Management of Energy Resources, University of Western Macedonia, 50100 Kozani (Greece)

2010-04-15T23:59:59.000Z

183

Phase-transient hierarchical turbulence as an energy correlation generator of blazar light curves  

E-Print Network [OSTI]

Hierarchical turbulent structure constituting a jet is considered to reproduce energy-dependent variability in blazars, particularly, the correlation between X- and gamma-ray light curves measured in the TeV blazar Markarian 421. The scale-invariant filaments are featured by the ordered magnetic fields that involve hydromagnetic fluctuations serving as electron scatterers for diffusive shock acceleration, and the spatial size scales are identified with the local maximum electron energies, which are reflected in the synchrotron spectral energy distribution (SED) above the near-infrared/optical break. The structural transition of filaments is found to be responsible for the observed change of spectral hysteresis.

Mitsuru Honda

2008-02-06T23:59:59.000Z

184

Turbulent equipartitions in two dimensional drift convection  

SciTech Connect (OSTI)

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.

Isichenko, M.B.; Yankov, V.V. [Univ. of California, Santa Barbara, CA (United States). Inst. for Theoretical Physics

1995-07-25T23:59:59.000Z

185

The Georgi Algorithms of Jet Clustering  

E-Print Network [OSTI]

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

Shao-Feng Ge

2014-08-30T23:59:59.000Z

186

NASA Subsonic Jet Transport Noise Reduction Research  

Science Journals Connector (OSTI)

Although new jet transport airplanes in today''s fleet are considerably quieter than the first jet transports introduced about 40 years ago, airport community noise continues to be an important environmental issue. NASA''s Advanced Subsonic Transport ...

Powell Clemans A.; Preisser John S.

2000-08-01T23:59:59.000Z

187

Coupling of twin rectangular supersonic jets  

E-Print Network [OSTI]

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

Raman, G.; Taghavi, Ray

1998-01-01T23:59:59.000Z

188

Gravity waves from vortex dipoles and jets  

E-Print Network [OSTI]

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...

Wang, Shuguang

2009-05-15T23:59:59.000Z

189

Numerical investigation of the effect of chevrons in subsonic jets using URANS  

Science Journals Connector (OSTI)

Numerical simulations of compressible, turbulent jets at M = 0.75 using the Shear Stress Transport (SST) k-? model have been carried out for baseline nozzle and chevron nozzles with 4, 6 and 8 lobes and three different penetration angles (0°, 5° and 10°). The predicted far field noise level at several observer locations are compared with experimental data. Overall sound pressure levels at far field observer locations have been calculated using Ffowcs Williams-Hawkings equation. Numerical prediction of aerodynamic quantities like centreline velocity, stagnation pressure, turbulent kinetic energy and axial vorticity are compared among the nozzles. The Unsteady Reynolds Averaged Navier Stokes (URANS) calculations are able to predict the trends in overall SPL, even though the absolute values are slightly under-predicted.

P.S. Tide; V. Babu

2010-01-01T23:59:59.000Z

190

Reflective ghost imaging through turbulence  

SciTech Connect (OSTI)

Recent work has indicated that ghost imaging may have applications in standoff sensing. However, most theoretical work has addressed transmission-based ghost imaging. To be a viable remote-sensing system, the ghost imager needs to image rough-surfaced targets in reflection through long, turbulent optical paths. We develop, within a Gaussian-state framework, expressions for the spatial resolution, image contrast, and signal-to-noise ratio of such a system. We consider rough-surfaced targets that create fully developed speckle in their returns and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths. We address both classical and nonclassical optical sources, as well as a computational ghost imager.

Hardy, Nicholas D.; Shapiro, Jeffrey H. [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-12-15T23:59:59.000Z

191

Jet physics at HERA, Tevatron and LHC  

E-Print Network [OSTI]

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

C. Royon

2008-11-10T23:59:59.000Z

192

Jets in relativistic heavy ion collisions  

SciTech Connect (OSTI)

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.

Wang, Xin-Nian; Gyulassy, M.

1990-09-01T23:59:59.000Z

193

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

SciTech Connect (OSTI)

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

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

2013-12-15T23:59:59.000Z

194

Quantifying Turbulence for Tidal Power Applications  

SciTech Connect (OSTI)

Using newly collected data from a tidal power site in Puget Sound, WA, metrics for turbulence quantification are assessed and discussed. The quality of raw ping Acoustic Doppler Current Profiler (ADCP) data for turbulence studies is evaluated against Acoustic Doppler Velocimeter (ADV) data at a point. Removal of Doppler noise from the raw ping data is shown to be a crucial step in turbulence quantification. Excluding periods of slack tide, the turbulent intensity estimates at a height of 4.6 m above the seabed are 8% and 11% from the ADCP and ADV, respectively. Estimates of the turbulent dissipation rate are more variable, from 10e-3 to 10e-1 W/m^3. An example analysis of coherent Turbulent Kinetic Energy (TKE) is presented.

Thomson, Jim; Richmond, Marshall C.; Polagye, Brian; Durgesh, Vibhav

2010-08-01T23:59:59.000Z

195

Equal distribution of satellite constellations on circular target orbits  

Science Journals Connector (OSTI)

Abstract This paper addresses the problem of equal distribution of satellite constellations on circular target orbits. The control goal is to make the constellation converge to a circular target orbit, while spatially distributing the satellites at equal inter-satellite distances. The solution is defined in the port-Hamiltonian framework, which gives a clear physical interpretation of the obtained control laws, insight into the energy consumption and complete stability proofs. The controller consists of two parts: the internal control system steers each individual satellite to the target orbit, the external control system equally distributes the satellite constellation. Numerical simulation results are given to illustrate the effectiveness of the approach.

Ewoud Vos; Jacquelien M.A. Scherpen; Arjan J. van der Schaft

2014-01-01T23:59:59.000Z

196

Odor Landscapes in Turbulent Environments  

Science Journals Connector (OSTI)

The olfactory system of male moths is exquisitely sensitive to pheromones emitted by females and transported in the environment by atmospheric turbulence. Moths respond to minute amounts of pheromones, and their behavior is sensitive to the fine-scale structure of turbulent plumes where pheromone concentration is detectible. The signal of pheromone whiffs is qualitatively known to be intermittent, yet quantitative characterization of its statistical properties is lacking. This challenging fluid dynamics problem is also relevant for entomology, neurobiology, and the technological design of olfactory stimulators aimed at reproducing physiological odor signals in well-controlled laboratory conditions. Here, we develop a Lagrangian approach to the transport of pheromones by turbulent flows and exploit it to predict the statistics of odor detection during olfactory searches. The theory yields explicit probability distributions for the intensity and the duration of pheromone detections, as well as their spacing in time. Predictions are favorably tested by using numerical simulations, laboratory experiments, and field data for the atmospheric surface layer. The resulting signal of odor detections lends itself to implementation with state-of-the-art technologies and quantifies the amount and the type of information that male moths can exploit during olfactory searches.

Antonio Celani; Emmanuel Villermaux; Massimo Vergassola

2014-10-28T23:59:59.000Z

197

Production of biocomponent containing jet fuels  

Science Journals Connector (OSTI)

Recent demands for low aromatic content jet fuels have shown significant increase in the last 20 years. This was generated by the growing of aviation. Further than quality requirements were more aggravated in front of jet fuels. This was generated by ... Keywords: aromatic content, biocomponent, crystallization point, jet fuel, kerosene, vegetable oil

Z. Eller; P. Solymosi; T. Kasza; Z. Varga; J. Hancsók

2011-12-01T23:59:59.000Z

198

The dispersion of dense effluent from an inclined jet discharging into still fluid  

E-Print Network [OSTI]

. Reid This thesis considers the dispersion of a dense effLuent, such as discharged by a desalination plant, in s. still, initially homogeneous fluid. The solution - s applica'ble near the effluent source where the momen- tum of the source... on the jet axis as a function of s E 0 F J 0 centerline value of s at the orifice nozzle densimetric Froude numbe: local densimetric Froude number acceleration due to gravity momentum transport from the source turbulent exchange co ff'cient defined...

Mitchell, Thomas Mark

2012-06-07T23:59:59.000Z

199

Two techniques for forecasting clear air turbulence  

E-Print Network [OSTI]

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

Arbeiter, Randolph George

2012-06-07T23:59:59.000Z

200

Effect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent  

E-Print Network [OSTI]

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

Martín, Pino

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Study of turbulence-chemistry interaction in hypersonic turbulent boundary layers  

E-Print Network [OSTI]

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

Martín, Pino

202

Heat release effects on decaying homogeneous compressible turbulence  

E-Print Network [OSTI]

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

Lee, Kurn Chul

2009-05-15T23:59:59.000Z

203

COHERENT STRUCTURES IN PLASMA TURBULENCE: PERSISTENCE, INTERMITTENCY...  

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

TURBULENCE: PERSISTENCE, INTERMITTENCY, AND CONNECTIONS WITH OBSERVATIONS by Kurt W. Smith A dissertation submitted in partial fulfillment of the requirements for the degree of...

204

Photoproduction of jets at NLO  

E-Print Network [OSTI]

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

B. W. Harris; J. F. Owens

1996-08-20T23:59:59.000Z

205

The Particle Content of Extragalactic Jets  

E-Print Network [OSTI]

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.

David S. De Young

2006-05-31T23:59:59.000Z

206

How to project `circular' manifolds using geodesic distances?  

E-Print Network [OSTI]

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

Verleysen, Michel

207

The First International Workshop on Synchrotron Radiation Circular Dichroism  

E-Print Network [OSTI]

The First International Workshop on Synchrotron Radiation Circular Dichroism (SRCD) Spectroscopy and biochemists and has been operational for about a year. Drs. Kunihiko Gekko (HiSOR, Japan) and Ye Tao (BSRF REPORTS SYNCHROTRON RADIATION NEWS, Vol. 15, No. 1, 2002 33 1st International Workshop on SRCD

Wallace, Bonnie Ann

208

Development of a circularly polarizing microscope with a polarizing undulator  

Science Journals Connector (OSTI)

A circularly polarizing microscope by which we intend to obtain images with CD (circular dichroism) or CIDS (circular intensity differential scattering) in order to observe the structure and distribution of biomolecules has been constructed by using a polarizing undulator as the polarizing light source. The polarizing undulator with crossed and retarded magnetic field having fifteen periods was installed in the electron storage ring NIJI?II in the Electrotechnical Laboratory. A Schwarzschild?type mirror system combined with a convex mirror was developed in order to focus the undulator radiation to a microbeam keeping the quality of polarization of the radiation from the undulator. The beam size was from 0.66 ?m (at wavelength 200 nm) to 0.96 ?m (at 400 nm). Using a scanning sample stage and a photomultiplier which was positioned in the back of the sample some images with transmitted and scattered light from fibrous DNA have been obtained. Attempts have also been made at obtaining images with CD and CIDS from the alternation between right? and left?handed circularly polarized radiation from the undulator.

Toru Yamada; Masatada Yuri; Hideo Onuki; Shozo Ishizaka

1995-01-01T23:59:59.000Z

209

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...

210

Buoyancy-generated variable-density turbulence  

SciTech Connect (OSTI)

Because of the importance of turbulence mixing in many applications, a number of turbulence mixing models have been proposed for variable- density flows. These engineering models (one- point statistical models) typically include the transport of the turbulent kinetic energy and the turbulent energy dissipation rate (i.e., k - {epsilon} models). The model presented by Besnard, Harlow, Rauenzahn and Zemach (1992) (herein referred to as BHRZ) is a one-point model intended to describe variable-density turbulent flows. Transport equations for the Reynolds stress tensor, R{sub ij}, and the turbulent energy dissipation rate, the density-velocity correlation, a{sub i}, and the density-specific volume correlation, b are derived. This model employs- techniques and concepts from incompressible, constant- density turbulence modeling and incorporates ideas from two-phase flow models. Clark and Spitz (1994) present a two-point model for variable-density turbulence. Their derivation is based on transport equations that, are based 0481 on two-point- generalizations of R{sub ij}, a{sub ij}, and b. These equations are Fourier transformed with respect to the separation distance between the two points. Transport equations are derived for R{sub ij}, a{sub i}, b. As in the one-point model, this model contains many ad-hoc assumptions and unknown model coefficients that must be determined by comparison with experimental and numerical data. However, the two-point formalism requires fewer equilibrium assumptions then does a single-point model. Our primary concern in this paper lies in the nonlinear processes of turbulence and the influence of large density variations (not within the Boussinesq limit) on these processes. To. isolate the effects of variable-density on the turbulence we restrict our flow to be incompressible, statistically homogeneous buoyancy-generated. turbulence. To our knowledge there have not been any simulations reported for this problem.

Sandoval, D.L.; Clark, T.T.; Riley, J.J.

1996-07-01T23:59:59.000Z

211

Synthetic jets at large Reynolds number and comparison to continuous jets  

SciTech Connect (OSTI)

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

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

2001-01-01T23:59:59.000Z

212

Jet Dipolarity: Top Tagging with Color Flow  

SciTech Connect (OSTI)

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.

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

2011-08-12T23:59:59.000Z

213

Turbulent transport of energetic ions  

SciTech Connect (OSTI)

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

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

2006-11-30T23:59:59.000Z

214

CHARACTERIZING MAGNETIZED TURBULENCE IN M51  

SciTech Connect (OSTI)

We use previously published high-resolution synchrotron polarization data to perform an angular dispersion analysis with the aim of characterizing magnetized turbulence in M51. We first analyze three distinct regions (the center of the galaxy, and the northwest and southwest spiral arms) and can clearly discern the turbulent correlation length scale from the width of the magnetized turbulent correlation function for two regions and detect the imprint of anisotropy in the turbulence for all three. Furthermore, analyzing the galaxy as a whole allows us to determine a two-dimensional Gaussian model for the magnetized turbulence in M51. We measure the turbulent correlation scales parallel and perpendicular to the local mean magnetic field to be, respectively, {delta}{sub ||} = 98 {+-} 5 pc and {delta} = 54 {+-} 3 pc, while the turbulent-to-ordered magnetic field strength ratio is found to be B{sub t}/B{sub 0} = 1.01 {+-} 0.04. These results are consistent with those of Fletcher et al., who performed a Faraday rotation dispersion analysis of the same data, and our detection of anisotropy is consistent with current magnetized turbulence theories.

Houde, Martin [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada)] [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Fletcher, Andrew [School of Mathematics and Statistics, Newcastle University, Newcastle-upon-Tyne NE1 7RU (United Kingdom)] [School of Mathematics and Statistics, Newcastle University, Newcastle-upon-Tyne NE1 7RU (United Kingdom); Beck, Rainer [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)] [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Hildebrand, Roger H. [Department of Astronomy and Astrophysics and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States)] [Department of Astronomy and Astrophysics and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States); Vaillancourt, John E. [Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, NASA Ames Research Center, Moffet Field, CA 94035 (United States)] [Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, NASA Ames Research Center, Moffet Field, CA 94035 (United States); Stil, Jeroen M. [Department of Physics and Astronomy, The University of Calgary, Calgary, AB T2N 1N4 (Canada)] [Department of Physics and Astronomy, The University of Calgary, Calgary, AB T2N 1N4 (Canada)

2013-03-20T23:59:59.000Z

215

Electric field statistics in MHD turbulence  

E-Print Network [OSTI]

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

Low, Robert

216

Stochastic models for turbulent reacting flows  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

217

On the dynamics of magnetorotational turbulent stresses  

Science Journals Connector (OSTI)

......C 5= 1 are adopted.The diagram is self-similar and therefore...corresponding to a state of steady MHD turbulence. A typical result...state of statistically steady MHD turbulence.The solution approached...stable. Figure 4 Stability diagram for rotating plane Couette flow......

G.I. Ogilvie

2003-04-11T23:59:59.000Z

218

AIAA-92-5101 Hypersonic Turbulent  

E-Print Network [OSTI]

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

Texas at Arlington, University of

219

Shape of isoshear contours in turbulent friction  

Science Journals Connector (OSTI)

We analyze line measurements of turbulent shear stress in a turbulent boundary layer in terms of isoshear contours. The statistics of the relative location of contour center lines points to a relation with coherent structures. The shape of these contours exhibits a remarkable scaling behavior that is reminiscent of that found in spatiotemporal chaos.

Willem van de Water and Eric van de Wetering

1992-06-15T23:59:59.000Z

220

Parametric Instabilities in Turbulent, Inhomogeneous Plasma  

Science Journals Connector (OSTI)

It is known that parametric instabilities involving two coupled modes, with oppositely directed group velocities, saturate convectively if the medium is inhomogeneous. This work considers the modification of that result when weak long-wave turbulence is present, in addition to the background inhomogeneity. We find that the convective saturation disappears when the turbulence exceeds a certain level, absolute growth occurring instead.

Dwight R. Nicholson and Allan N. Kaufman

1974-11-11T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Policy Flash 2014-03 Federal Acquisition Circular 2005-70 | Department...  

Energy Savers [EERE]

3 Federal Acquisition Circular 2005-70 Policy Flash 2014-03 Federal Acquisition Circular 2005-70 Questions concerning this policy flash should be directed to Barbara Binney, of the...

222

Electromagnetic weak turbulence theory revisited  

SciTech Connect (OSTI)

The statistical mechanical reformulation of weak turbulence theory for unmagnetized plasmas including fully electromagnetic effects was carried out by Yoon [Phys. Plasmas 13, 022302 (2006)]. However, the wave kinetic equation for the transverse wave ignores the nonlinear three-wave interaction that involves two transverse waves and a Langmuir wave, the incoherent analogue of the so-called Raman scattering process, which may account for the third and higher-harmonic plasma emissions. The present paper extends the previous formalism by including such a term.

Yoon, P. H. [IPST, University of Maryland, College Park, Maryland 20742 (United States); Ziebell, L. F. [Instituto de Fisica, UFRGS, Porto Alegre, RS (Brazil); Gaelzer, R.; Pavan, J. [Instituto de Fisica e Matematica, UFPel, Pelotas, RS (Brazil)

2012-10-15T23:59:59.000Z

223

On observing acoustic backscattering from salinity turbulence  

Science Journals Connector (OSTI)

It has been hypothesized that at sufficiently high levels of oceanic salinity turbulence it should be possible to observe acoustic backscattering. However there have been limited in situmeasurements to confirm this hypothesis. Using an autonomous underwater vehicle equipped with upward and downward looking 1.2 MHz acoustic Doppler current profilers and with turbulence and fine scale sensors measurements were performed in a region of intense turbulence and a strong salinity gradient. The approach taken was to correlate variations in the backscattered acoustic intensity I with a theoretical acoustic backscattering cross section per volume for salinity turbulence ? s to obtain an estimated scattering cross section per volume ? e . Results indicated that of order 50% of the observed region was characterized by salinity turbulence induced backscattering.

Louis Goodman; Marcos M. Sastre-Córdova

2011-01-01T23:59:59.000Z

224

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

SciTech Connect (OSTI)

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

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

2006-03-02T23:59:59.000Z

225

CASING EFFECTS ON THE RADIATION PERFORMANCE OF A CIRCULARLY POLARIZED PATCH ANTENNA  

E-Print Network [OSTI]

CASING EFFECTS ON THE RADIATION PERFORMANCE OF A CIRCULARLY POLARIZED PATCH ANTENNA K. Rambabu, H on the radiation characteristics of a miniaturized patch antenna for circular polarization. Different scenarios DESIGN Using a multiple resonance technique [4] for broadband performance, a circularly polarized patch

Bornemann, Jens

226

Simple thermodynamics of jet engines  

Science Journals Connector (OSTI)

We use the first and second laws of thermodynamics to analyze the behavior of an ideal jet engine. Simple analytical expressions for the thermal efficiency the overall efficiency and the reduced thrust are derived. We show that the thermal efficiency depends only on the compression ratio r and on the velocity of the aircraft. The other two performance measures depend also on the ratio of the temperature at the turbine to the inlet temperature in the engine T 3 / T i . An analysis of these expressions shows that it is not possible to choose an optimal set of values of r and T 3 / T i that maximize both the overall efficiency and thrust. We study how irreversibilities in the compressor and the turbine decrease the overall efficiency of jet engines and show that this effect is more pronounced for smaller T 3 / T i .

Pedro Patrício; José M. Tavares

2010-01-01T23:59:59.000Z

227

Numerical Simulations of Bouncing Jets  

E-Print Network [OSTI]

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

Lee, Sanghyun

2014-07-18T23:59:59.000Z

228

Film cooling performance and heat transfer over an inclined film-cooled surface at different divergent angles with respect to highly turbulent mainstream  

SciTech Connect (OSTI)

Experiments have been performed to study and obtain the adiabatic wall film cooling effectiveness and the heat transfer over a film-cooled surface that is made inclined at various angles with respect to a highly turbulent flow. The vertical temperature distribution was measured to infer the flow structure and the rate of mixing of film jet with the freestream. The freestream turbulence intensity is controlled to range from 1.0% to 26.4%, the inclination or the divergent angle of the film-cooled surface ranges from 0 to 20 , the blowing parameter from 0.5 to 2.0. It is found that the mixing of the film jet with the freestream is significantly enhanced by both the freestream turbulence intensity and the divergent angle of the film-cooled surface, which leads to the decrease in the film cooling effectiveness and the increase in the heat transfer. However, the inclination angle has more effect on the film cooling performance while the turbulence intensity has more effect on the heat transfer under the film. More detailed discussion is presented. Correlations for both the film cooling effectiveness and the heat transfer under the film-cooled surface have been very successful and are provided. (author)

Yang, Chih-Sheng [Department of Computer Science and Information Engineering Far East University (China); Lin, C.L.; Gau, C. [Institute of Aeronautics and Astronautics, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101 (China)

2008-05-15T23:59:59.000Z

229

Federal Acquisition Circular 2005-52 Item Subject FAR case  

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

Circular 2005-52 Circular 2005-52 Item Subject FAR case I Sustainable Acquisition 2010-001 II Contract Closeout 2008-020 III Prohibition on Contracting with Inverted Domestic Corporations 2008-009 IV Buy American Exemption for Commercial Information Technology - Construction Material 2009-039 V Oversight of Contractor Ethics Programs 2010-017 VI Technical Amendments N/A Item I--Sustainable Acquisition (FAR Case 2010-001) (Interim) This interim rule amends the FAR to implement Executive Order 13514, Federal Leadership in Environmental, Energy, and Economic Performance, and Executive Order 13423, Strengthening Federal Environmental, Energy, and Transportation Management. It requires Federal agencies to leverage agency acquisitions to foster markets for

230

Heat Transport by Turbulent Rayleigh-Benard Convection  

SciTech Connect (OSTI)

We have developed a research program dedicated to the quantitative laboratory study of turbulent convection.

None

2008-10-03T23:59:59.000Z

231

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

SciTech Connect (OSTI)

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

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

2006-12-01T23:59:59.000Z

232

Combining Resummed Higgs Predictions Across Jet Bins  

E-Print Network [OSTI]

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

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

2013-12-16T23:59:59.000Z

233

Federal Acquisition Regulation; Federal Acquisition Circular 2005-47; Summary  

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

7; Summary 7; Summary This document summarizes the Federal Acquisition Regulation (FAR) rules agreed to by the Civilian Agency Acquisition Council and the Defense Acquisition Regulations Council (Councils) in this Federal Acquisition Circular (FAC) 2005-47. All were effective December 13, 2010 except Items II, HUB Zone, and VI, Pass Through, which will be effective January 12, 2011. List of Rules in FAC 2005-47 Item Subject FAR case Analyst ------------------------------------------------------------------------------------------------------------ ---- I..................................... Notification of Employee 2010-006 McFadden.

234

Circular polarization of obliquely propagating whistler wave magnetic field  

SciTech Connect (OSTI)

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.

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

2013-08-15T23:59:59.000Z

235

Circular hydraulic jump in generalized-Newtonian fluids  

E-Print Network [OSTI]

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

Rai, Ashutosh; Poria, Swarup

2008-01-01T23:59:59.000Z

236

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

E-Print Network [OSTI]

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

237

Circular modes for flat beams in the LHC  

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

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

Burov, A.

2013-06-01T23:59:59.000Z

238

Circular modes for flat beams in the LHC  

Science Journals Connector (OSTI)

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

A. Burov

2013-06-24T23:59:59.000Z

239

LDV Measurement of Confined Parallel Jet Mixing  

SciTech Connect (OSTI)

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

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

2001-01-31T23:59:59.000Z

240

Jet-calculus approach including coherence effects  

Science Journals Connector (OSTI)

We show how integrodifferential equations typical of jet calculus can be combined with an averaging procedure to obtain jet-calculus-based results including the Mueller interference graphs. Results in longitudinal-momentum fraction x for physical quantities are higher at intermediate x and lower at large x than with the conventional ‘‘incoherent’’ jet calculus. These results resemble those of Marchesini and Webber, who used a Monte Carlo approach based on the same dynamics.

L. M. Jones; R. Migneron; K. S. S. Narayanan

1987-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

File:DEQ MFSA Circular 1.pdf | Open Energy Information  

Open Energy Info (EERE)

DEQ MFSA Circular 1.pdf DEQ MFSA Circular 1.pdf Jump to: navigation, search File File history File usage File:DEQ MFSA Circular 1.pdf Size of this preview: 463 × 599 pixels. Other resolution: 464 × 600 pixels. Go to page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Go! next page → next page → Full resolution ‎(1,275 × 1,650 pixels, file size: 313 KB, MIME type: application/pdf, 33 pages) File history Click on a date/time to view the file as it appeared at that time. Date/Time Thumbnail Dimensions User Comment current 16:00, 9 October 2012 Thumbnail for version as of 16:00, 9 October 2012 1,275 × 1,650, 33 pages (313 KB) Dklein2012 (Talk | contribs) You cannot overwrite this file. Edit this file using an external application (See the setup

242

NON-ZEEMAN CIRCULAR POLARIZATION OF MOLECULAR ROTATIONAL SPECTRAL LINES  

SciTech Connect (OSTI)

We present measurements of circular polarization from rotational spectral lines of molecular species in Orion KL, most notably {sup 12}CO (J = 2 {yields} 1), obtained at the Caltech Submillimeter Observatory with the Four-Stokes-Parameter Spectral Line Polarimeter. We find levels of polarization of up to 1%-2% in general; for {sup 12}CO (J = 2 {yields} 1) this level is comparable to that of linear polarization also measured for that line. We present a physical model based on resonant scattering in an attempt to explain our observations. We discuss how slight differences in scattering amplitudes for radiation polarized parallel and perpendicular to the ambient magnetic field, responsible for the alignment of the scattering molecules, can lead to the observed circular polarization. We also show that the effect is proportional to the square of the magnitude of the plane of the sky component of the magnetic field and therefore opens up the possibility of measuring this parameter from circular polarization measurements of Zeeman insensitive molecules.

Houde, Martin; Jones, Scott; Rajabi, Fereshte [Department of Physics and Astronomy, The University of Western Ontario, London, ON, N6A 3K7 (Canada)] [Department of Physics and Astronomy, The University of Western Ontario, London, ON, N6A 3K7 (Canada); Hezareh, Talayeh [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)] [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

2013-02-10T23:59:59.000Z

243

Dynamical evolution of quasi-circular binary black hole data  

E-Print Network [OSTI]

We study the fully nonlinear dynamical evolution of binary black hole data, whose orbital parameters are specified via the effective potential method for determining quasi-circular orbits. The cases studied range from the Cook-Baumgarte innermost stable circular orbit (ISCO) to significantly beyond that separation. In all cases we find the black holes to coalesce (as determined by the appearance of a common apparent horizon) in less than half an orbital period. The results of the numerical simulations indicate that the initial holes are not actually in quasi-circular orbits, but that they are in fact nearly plunging together. The dynamics of the final horizon are studied to determine physical parameters of the final black hole, such as its spin, mass, and oscillation frequency, revealing information about the inspiral process. We show that considerable resolution is required to extract accurate physical information from the final black hole formed in the merger process, and that the quasi-normal modes of the final hole are strongly excited in the merger process. For the ISCO case, by comparing physical measurements of the final black hole formed to the initial data, we estimate that less than 3% of the total energy is radiated in the merger process.

Miguel Alcubierre; Bernd Bruegmann; Peter Diener; F. Siddhartha Guzman; Ian Hawke; Scott Hawley; Frank Herrmann; Michael Koppitz; Denis Pollney; Edward Seidel; Jonathan Thornburg

2004-11-30T23:59:59.000Z

244

Entropy Production in Relativistic Jet Boundary Layers  

E-Print Network [OSTI]

Hot relativistic jets, passing through a background medium with a pressure gradient p \\propto r^{-\\eta} where 2 gamma-ray bursts from ...

Kohler, Susanna

2014-01-01T23:59:59.000Z

245

Atmospheric Plasma Jet Machining of Optical Surfaces  

Science Journals Connector (OSTI)

Deterministic surface machining with high spatial resolution and nanometric depth accuracy is urgently required in the fabrication of high-end optics. Thus, plasma jet tools with...

Böhm, Georg; Eichentopf, Inga-Maria; Arnold, Thomas

246

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

E-Print Network [OSTI]

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

Alam, Syed Aftab

2012-06-07T23:59:59.000Z

247

Free Energy Cascade in Gyrokinetic Turbulence  

SciTech Connect (OSTI)

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

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

2011-02-04T23:59:59.000Z

248

Coshcous turbulence and its thermalization  

SciTech Connect (OSTI)

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

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

2008-01-01T23:59:59.000Z

249

E-Print Network 3.0 - advanced turbulence models Sample Search...  

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

modelling, super-fluid turbulence, MHD and 2... -dimensional turbulence. Thanks to recent spectacular advances in the numerical simulation of turbulence... of ... Source:...

250

Plasma jets and plasma bullets  

Science Journals Connector (OSTI)

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]–[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 35–50% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 1948–1990130031 1991–19952279456 1996–20003447689 2001–20054571914 2006–201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ?0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective technological solution in the early to late 1990s of confining atmospheric plasmas in a small v

M G Kong; B N Ganguly; R F Hicks

2012-01-01T23:59:59.000Z

251

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

E-Print Network [OSTI]

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

Roman, Jennifer Claire

1996-01-01T23:59:59.000Z

252

Resuspension and Sedimentation of Particles from a Sediment Bed by Turbulent Jets  

Science Journals Connector (OSTI)

An experimental study was carried out to investigate the resuspension of heavy particles of a sediment bed ... . The results were extrapolated to study sediment resuspension in karstic lakes, especially lake Bany...

Jordi Colomer; Xavier Casamitjana; Harindra J.S. Fernando

1997-01-01T23:59:59.000Z

253

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

E-Print Network [OSTI]

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

Ray, Jaideep

254

Space variations in axis height of the jet stream core  

E-Print Network [OSTI]

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

Leutwyler, Cooke Hearon

1965-01-01T23:59:59.000Z

255

Supercomputers Capture Turbulence in the Solar Wind  

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

Supercomputers Supercomputers Capture Turbulence in the Solar Wind Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space weather December 16, 2013 Linda Vu, +1 510 495 2402, lvu@lbl.gov eddies1.jpg This visualization zooms in on current sheets revealing the "cascade of turbulence" in the solar wind occurring down to electron scales. This is a phenomenon common in fluid dynamics-turbulent energy injected at large eddies is transported to successively smaller scales until it is dissipated as heat. (Image by Burlen Loring, Berkeley Lab) As inhabitants of Earth, our lives are dominated by weather. Not just in the form of rain and snow from atmospheric clouds, but also a sea of charged particles and magnetic fields generated by a star sitting 93

256

Active skin for turbulent drag reduction  

E-Print Network [OSTI]

evidence that spanwise traveling waves of the right amplitude, wavelength and frequency can result in significant turbulent drag reduction. Such traveling waves can be induced in the smart skin via active-material actuation. The flow control technique...

Mani, Raghavendran

2002-01-01T23:59:59.000Z

257

Turbulence in Astrophysical and Laboratory Plasmas  

E-Print Network [OSTI]

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

Shyy, Wei

258

Turbulent Dynamics in the Solar Convection Zone  

Science Journals Connector (OSTI)

...nonisotropic, ra-diative, inhomogeneous MHD turbulence. Considering the effort that...helioseismic methods based on such ring diagram and phase analyses (24) may provide...Ser. 76, 208 (1995). 24. Ring diagram methods applied to local wave fields are...

Nicholas Brummell; Juri Toomre; Fausto Cattaneo

1995-09-08T23:59:59.000Z

259

TIDAL TURBULENCE SPECTRA FROM A COMPLIANT MOORING  

SciTech Connect (OSTI)

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.

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

2013-06-13T23:59:59.000Z

260

Turbulent diffusion with rotation or magnetic fields  

E-Print Network [OSTI]

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

Brandenburg, Axel; Vasil, Geoffrey M

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Estimating Oceanic Turbulence Dissipation from Seismic Images  

Science Journals Connector (OSTI)

Seismic images of oceanic thermohaline finestructure record vertical displacements from internal waves and turbulence over large sections at unprecedented horizontal resolution. Where reflections follow isopycnals, their displacements can be used ...

W. Steven Holbrook; Ilker Fer; Raymond W. Schmitt; Daniel Lizarralde; Jody M. Klymak; L. Cody Helfrich; Robert Kubichek

2013-08-01T23:59:59.000Z

262

Inhomogeneous distribution of droplets in cloud turbulence  

E-Print Network [OSTI]

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.

Itzhak Fouxon; Yongnam Park; Roei Harduf; Changhoon Lee

2014-10-30T23:59:59.000Z

263

Fractional and fractal derivatives modeling of turbulence  

E-Print Network [OSTI]

This study makes the first attempt to use the 2/3-order fractional Laplacian modeling of enhanced diffusing movements of random turbulent particle resulting from nonlinear inertial interactions. A combined effect of the inertial interactions and the molecule Brownian diffusivities is found to be the bi-fractal mechanism behind multifractal scaling in the inertial range of scales of moderate Reynolds number turbulence. Accordingly, a stochastic equation is proposed to describe turbulence intermittency. The 2/3-order fractional Laplacian representation is also used to construct a fractional Reynolds equation for nonlinear interactions of fluctuating velocity components, underlying turbulence spacetime fractal structures of Levy 2/3 stable distribution. The new perspective of this study is that the fractional calculus is an effective approach modeling of chaotic fractal phenomena induced by nonlinear interactions.

Wen Chen

2005-11-30T23:59:59.000Z

264

Simulation of jets at colliders  

Science Journals Connector (OSTI)

Abstract We review the development of the physics behind event generators during the last decade. After a more general description of parton showers, we focus mostly on the perturbative side of the simulations. Two newer developments of parton showers, as implemented in herwig++, are described in greater detail. Matching and merging of parton showers with fixed order computations are discussed. We describe some developments of multiple partonic interactions which are relevant for the simulation of jets from the underlying event, where the implementation in herwig++  is again taken as a generic example. Finally, we compare some event generator results to collider data from LEP and the LHC.

Stefan Gieseke

2013-01-01T23:59:59.000Z

265

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

Science Journals Connector (OSTI)

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.

2013-01-01T23:59:59.000Z

266

Turbulent structures and budgets behind permeable ribs  

SciTech Connect (OSTI)

Different rib geometries are traditionally used to improve heat transfer and enhance mixing in different industrial applications, i.e. heat exchangers, cooling passages of gas turbine blades and fuel elements of nuclear reactors, etc. Permeable ribs have been proposed in literature for passive control of the reattaching flow past surface mounted ribs leading to superior performance. The flow past different surface mounted permeable rib geometries, i.e. solid, slit, split-slit and inclined split-slit ribs have been investigated in this study. Both two components and stereo particle image velocimetry (PIV) have been used in streamwise and cross stream planes to study the underlying flow structures. The detailed turbulent statistics, i.e. mean and rms velocity, higher order moments, quadrant decomposition of turbulent shear stress producing motions, skewness and components of the turbulent kinetic energy budgets have been compared for different rib geometries. Coherent structures are identified based on the invariant of velocity gradient tensor invariant and wavelet transform. The skewness results demonstrate the intermittency of quadrant motions. The reattachment length of the inclined split-slit rib is lowest among all rib geometries. The average Reynolds stresses and the production of turbulent kinetic energy are highest for the inclined split-slit rib. The pressure transport calculated as residual of the turbulent kinetic energy budget equation is highest for the inclined split-slit rib. This is attributed to the smaller reattachment length leading to greater adverse pressure gradient for the inclined split-slit rib. The quadrant motions, turbulent fluxes, skewness and kinetic energy budgets at post reattachment region compares well with that of flat plate turbulent boundary layer from hot wire measurements in literature. Overall, this study demonstrates the effectiveness of PIV technique for the detailed turbulent structures characterization of complex flows. (author)

Panigrahi, P.K. [Department of Mechanical Engineering, IIT Kanpur, UP 208016 (India); Schroeder, A.; Kompenhans, J. [Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Goettingen (Germany)

2008-02-15T23:59:59.000Z

267

Buoyancy-generated variable-density turbulence  

SciTech Connect (OSTI)

Both a one-point (engineering) and a two-point (spectral) model are tested against numerical data. Deficiencies in these variable-density models are disucssed and modifications are suggested. Attention is restricted to turbulent interactions of two miscible, incompressible Newtonian fluids of different densities. Departures from the limits of validity of the Boussinesq approximation are examined. Results of the buoyancy-generated turbulence are compared with variable-density model predictions. 3 figs, 6 refs.

Sandoval, D.L. [Los Alamos National Lab., NM (United States)]|[Washington Univ. (United States); Clark, T.T. [Los Alamos National Lab., NM (United States); Riley, J.J. [Washington Univ. (United States)

1996-06-01T23:59:59.000Z

268

Phenomenology of turbulent dynamo growth and saturation  

E-Print Network [OSTI]

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

Rodion Stepanov; Franck Plunian

2007-11-08T23:59:59.000Z

269

Principles of Jet Propulsion and Gas Turbines  

Science Journals Connector (OSTI)

... the presentation of the basic theory of jet propulsion and the thermodynamics of the gas-turbine and rocket types of engine. The layout follows a logical sequence, on the whole ... reader is treated to the now well-known thermodynamic analysis of the power-producing gas turbine cycle, which seems rather misplaced in a book dealing with jet propulsion. In his ...

S. J. MOYES

1949-08-06T23:59:59.000Z

270

Cover: Mariner 9 spacecraft. JET PROPULSION  

E-Print Network [OSTI]

#12;Cover: Mariner 9 spacecraft. #12;JET PROPULSION LABORATORY 1971 ANNUAL REPORT A descrtptlon Jet Propulsion Laboratory CALIFORNIA INSTITUTE OF TECHNOLOGY 4800 OAK GROVE DRIVE PASADENA, CALIFORNIA 91103 #12;#12;DIRECTOR'S MESSAGE The successful orbiting of Mariner 9 around the planet Mars

Waliser, Duane E.

271

Miniconference on astrophysical jets P. M. Bellan  

E-Print Network [OSTI]

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

Bellan, Paul M.

272

Jet multiplicities as the QGP thermometer  

E-Print Network [OSTI]

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

I. M. Dremin; O. S. Shadrin

2006-02-10T23:59:59.000Z

273

Reaction and diffusion in turbulent combustion  

SciTech Connect (OSTI)

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.

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

1993-12-01T23:59:59.000Z

274

Scaling, Intermittency and Decay of MHD Turbulence  

E-Print Network [OSTI]

We discuss a few recent developments that are important for understanding of MHD turbulence. First, MHD turbulence is not so messy as it is usually believed. In fact, the notion of strong non-linear coupling of compressible and incompressible motions along MHD cascade is not tenable. Alfven, slow and fast modes of MHD turbulence follow their own cascades and exhibit degrees of anisotropy consistent with theoretical expectations. Second, the fast decay of turbulence is not related to the compressibility of fluid. Rates of decay of compressible and incompressible motions are very similar. Third, viscosity by neutrals does not suppress MHD turbulence in a partially ionized gas. Instead, MHD turbulence develops magnetic cascade at scales below the scale at which neutrals damp ordinary hydrodynamic motions. Forth, density statistics does not exhibit the universality that the velocity and magnetic field do. For instance, at small Mach numbers the density is anisotropic, but it gets isotropic at high Mach numbers. Fifth, the intermittency of magnetic field and velocity are different. Both depend on whether the measurements are done in local system of reference oriented along the local magnetic field or in the global system of reference related to the mean magnetic field.

A. Lazarian; J. Cho

2004-08-10T23:59:59.000Z

275

Strong circular photogalvanic effect in ZnO epitaxial films  

SciTech Connect (OSTI)

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

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

2011-12-23T23:59:59.000Z

276

Analysis of transverse apertures in a circular waveguide  

E-Print Network [OSTI]

, (r, g, z) + H, (r, g, z) = h(r, g)en&' + h, (r, P)ei"*' where E, and H, are the transverse field components and E, and H, are the axial field components of the waveguide fields. By substitution of the previous decompositions into Maxwell's equauons... equation Vzhz + gihz =0 h, is equal to the scalar function V given in equation (10. b). Therefore, the axial magnetic field can be written as hx = ttr = J?(k, r) ( sin(nP) or cos(ntIt) ) e-i? (17) 15 For the circular waveguide cross section shown...

Eastham, Gary Bryan

2012-06-07T23:59:59.000Z

277

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

E-Print Network [OSTI]

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

Ballentine, John Richard

2012-06-07T23:59:59.000Z

278

Wave induced forces on a partially exposed circular cylinder  

E-Print Network [OSTI]

to determine the wave forces on a pipeline rest. ing on the bottom partia'lly embeded in surrounding sediments was conducted. The forces were measured by strain gauge load cells and recorded on an electronic strip chart recorder. The resulting forces were... Associated with the Potential Function of Stokes' 3rd Order Wave Theory Fluid Density Circular Have Frequency (ML a) O'-. 'APTER I IN RJCUCTION Since the Tate nineteenth century, men have been constructing various types of pipelines in t"e ocean...

Parker, Michael Edward

2012-06-07T23:59:59.000Z

279

Nature of Subproton Scale Turbulence in the Solar Wind  

Science Journals Connector (OSTI)

The nature of subproton scale fluctuations in the solar wind is an open question, partly because two similar types of electromagnetic turbulence can occur: kinetic Alfvén turbulence and whistler turbulence. These two possibilities, however, have one key qualitative difference: whistler turbulence, unlike kinetic Alfvén turbulence, has negligible power in density fluctuations. In this Letter, we present new observational data, as well as analytical and numerical results, to investigate this difference. These results show, for the first time, that the fluctuations well below the proton scale are predominantly kinetic Alfvén turbulence, and, if present at all, the whistler fluctuations make up only a small fraction of the total energy.

C. H. K. Chen; S. Boldyrev; Q. Xia; J. C. Perez

2013-05-31T23:59:59.000Z

280

Recent results on analytical plasma turbulence theory: Realizability, intermittency, submarginal turbulence, and self-organized criticality  

SciTech Connect (OSTI)

Recent results and future challenges in the systematic analytical description of plasma turbulence are described. First, the importance of statistical realizability is stressed, and the development and successes of the Realizable Markovian Closure are briefly reviewed. Next, submarginal turbulence (linearly stable but nonlinearly self-sustained fluctuations) is considered and the relevance of nonlinear instability in neutral-fluid shear flows to submarginal turbulence in magnetized plasmas is discussed. For the Hasegawa-Wakatani equations, a self-consistency loop that leads to steady-state vortex regeneration in the presence of dissipation is demonstrated and a partial unification of recent work of Drake (for plasmas) and of Waleffe (for neutral fluids) is given. Brief remarks are made on the difficulties facing a quantitatively accurate statistical description of submarginal turbulence. Finally, possible connections between intermittency, submarginal turbulence, and self-organized criticality (SOC) are considered and outstanding questions are identified.

Krommes, J.A.

2000-01-18T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Heat transfer and friction factor analysis in a circular tube with Al2O3 nanofluid by using computational fluid dynamics  

Science Journals Connector (OSTI)

Turbulent fully developed flow heat transfer coefficient and friction factor of Al2O3 nanoparticles are dispersed in water and ethylene glycol in circular tube is discussed in this paper. In order to validate the heat transfer coefficient and friction factor of nanofluid in circular tube commercially available CFD software FLUENT 6.0 is used. To achieve the fully developed flow condition, the aspect ratio (L/D) of the test section is equal to 94. The thermo-physical properties of the Al2O3 nanofluid are estimated by using the equations available in literature. Thermo-physical properties of the nanofluid are considered for heat transfer coefficient and friction factor by assuming nanofluid is a single-phase fluid. Constant Wall Heat Flux (CWHF) boundary condition is incorporated for heat transfer analysis and adiabatic boundary condition is incorporated for friction factor analysis. The analysis is conducted in the volume concentration range from 0.1% to 4%. A maximum of 2.25 times heat transfer enhancement and 1.42 times of friction is obtained by using nanofluid as working medium.

L. Syam Sundar; K.V. Sharma; Shabana Parveen

2009-01-01T23:59:59.000Z

282

Cylindrical Circular and Elliptical, Toroidal Circular and Elliptical Multipoles Fields, Potentials and their Measurement for Accelerator Magnets  

E-Print Network [OSTI]

Recent progress in particle accelerator tracking has shown that the field representation is one of the major limits of the prediction accuracy especially for machines, whose aperture is fully filled by the beam and thus higher the artefacts created by higher order modes have to be thoroughly understood. The standard tool for field presentation today are cylindrical circular multipoles due to their straight forward correspondence to the Cartesian coordinates. In this paper we extend the standard approach to other coordinate systems, show how these can be measured next to their realisation in measuring the SIS100 Magnets for the FAIR project.

Schnizer, Pierre; Schnizer, Bernhard

2014-01-01T23:59:59.000Z

283

NEAR-INFRARED CIRCULAR POLARIZATION IMAGES OF NGC 6334-V  

SciTech Connect (OSTI)

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.

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

2013-03-01T23:59:59.000Z

284

Composite Octet Searches with Jet Substructure  

SciTech Connect (OSTI)

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

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

2012-02-14T23:59:59.000Z

285

Dark jets in solar coronal holes  

E-Print Network [OSTI]

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

Young, Peter R

2015-01-01T23:59:59.000Z

286

Jet Reconstruction in Heavy Ion Collisions  

E-Print Network [OSTI]

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

Sevil Salur

2009-05-12T23:59:59.000Z

287

Jet production in ep collisions Pierre Van Mechelen  

E-Print Network [OSTI]

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

288

Numerical simulation of wind resonance of a circular profile by means of the vortex element method  

Science Journals Connector (OSTI)

The problem regarding the numerical simulation of a circular profile motion in a ... element method is used. The phenomenon of wind resonance has been examined. The investigation has...

I. K. Marchevskii; O. I. Ivanov

2009-10-01T23:59:59.000Z

289

An experimental study on heat transfer from a horizontal heated circular cylinder enhanced by water spray.  

E-Print Network [OSTI]

??A series of experiments were conducted to investigate the heat transfer which occurs with a heated, constant heat flux, horizontal, single circular cylinder is exposed… (more)

Chau, Man Hei

2009-01-01T23:59:59.000Z

290

Circular diffuse scattering of akermanite studied by the optical diffraction method  

Science Journals Connector (OSTI)

Circular diffuse scattering appears when the incommensurate phase of akermanite transforms partly to either the normal phase ... constant phase difference within each layer of the akermanite structure.

K. Iishi; K. Hagiya; M. Ohmasa

1994-05-01T23:59:59.000Z

291

Anisotropic turbulent model for solar coronal heating  

E-Print Network [OSTI]

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

B. Bigot; S. Galtier; H. Politano

2007-12-12T23:59:59.000Z

292

Squark and gluino production with jets  

SciTech Connect (OSTI)

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

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

2005-10-01T23:59:59.000Z

293

Jet spoiler arrangement for wind turbine  

DOE Patents [OSTI]

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

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

1983-09-15T23:59:59.000Z

294

Top quark jets at the LHC  

Science Journals Connector (OSTI)

We investigate the reconstruction of high pT hadronically decaying top quarks at the Large Hadron Collider. One of the main challenges in identifying energetic top quarks is that the decay products become increasingly collimated. This reduces the efficacy of conventional reconstruction methods that exploit the topology of the top quark decay chain. We focus on the cases where the decay products of the top quark are reconstructed as a single jet, a “top jet.” The most basic “top-tagging” method based on jet mass measurement is considered in detail. To analyze the feasibility of the top-tagging method, both theoretical and experimental aspects of the large QCD jet background contribution are examined. Based on a factorization approach, we derive a simple analytic approximation for the shape of the QCD jet mass spectrum. We observe very good agreement with the Monte Carlo simulation. We consider high-pT tt¯ production in the standard model as an example, and show that our theoretical QCD jet mass distributions can efficiently characterize the background via sideband analyses. We show that with 25??fb-1 of data, our approach allows us to resolve top jets with pT?1??TeV, from the QCD background, and about 1.5 TeV top jets with 100??fb-1, without relying on b-tagging. To further improve the significance we consider jet shapes (recently analyzed in 10), which resolve the substructure of energy flow inside cone jets. A method of measuring the top quark polarization by using the transverse momentum of the bottom quark is also presented. The main advantages of our approach are (i) the mass distributions are driven by first principle calculations, instead of relying solely on Monte Carlo simulation; (ii) for high pT jets (pT?1??TeV), IR-safe jet shape variables are robust against detector resolution effects. Our analysis can be applied to other boosted massive particles such as the electroweak gauge bosons and the Higgs.

Leandro G. Almeida; Seung J. Lee; Gilad Perez; Ilmo Sung; Joseph Virzi

2009-04-16T23:59:59.000Z

295

Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids  

E-Print Network [OSTI]

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

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

2008-01-01T23:59:59.000Z

296

Drag, turbulence, and diffusion in flow through emergent vegetation  

E-Print Network [OSTI]

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. ...

Nepf, Heidi

297

Examining A Hypersonic Turbulent Boundary Layer at Low Reynolds Number  

E-Print Network [OSTI]

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 unique research facility...

Semper, Michael Thomas

2013-05-15T23:59:59.000Z

298

Biophysical coupling between turbulence, veliger behavior, and larval supply  

E-Print Network [OSTI]

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 ...

Fuchs, Heidi L

2005-01-01T23:59:59.000Z

299

Velcro Measurement of Turbulence Kinetic Energy Dissipation Rate ?  

Science Journals Connector (OSTI)

Turbulence in the ocean results from many different processes operating over a wide range of space scales and timescales, with spatial and temporal variability particularly extreme in coastal oceans. If the origins and effects of turbulent ...

Ann E. Gargett

1999-12-01T23:59:59.000Z

300

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

E-Print Network [OSTI]

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

McDonald, Kirk

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Large eddy simulation of turbulence within heat exchangers  

E-Print Network [OSTI]

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

Pruitt, John Myron

2012-06-07T23:59:59.000Z

302

Supercomputers Capture Turbulence in the Solar Wind  

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

Supercomputers Capture Supercomputers Capture Turbulence in the Solar Wind News & Publications ESnet in the News ESnet News Media & Press Publications and Presentations Galleries ESnet Awards and Honors Contact Us Technical Assistance: 1 800-33-ESnet (Inside the US) 1 800-333-7638 (Inside the US) 1 510-486-7600 (Globally) 1 510-486-7607 (Globally) Report Network Problems: trouble@es.net Provide Web Site Feedback: info@es.net Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space weather December 16, 2013 | Tags: ESnet News, National Energy Research Scientific Computing Linda Vu, +1 510 495 2402, lvu@lbl.gov eddies1.jpg This visualization zooms in on current sheets revealing the "cascade of turbulence" in the solar wind occurring down to electron scales. This is

303

Spatial and Spectral evolution of Turbulence Spectra  

SciTech Connect (OSTI)

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

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

2006-11-30T23:59:59.000Z

304

A signature for turbulence driven magnetic islands  

SciTech Connect (OSTI)

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.

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

2014-09-15T23:59:59.000Z

305

Turbulence attenuation by large neutrally buoyant particles  

E-Print Network [OSTI]

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

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

2015-01-01T23:59:59.000Z

306

Modelling suspended sediment in environmental turbulent fluids  

E-Print Network [OSTI]

Modelling sediment transport in environmental turbulent fluids is a challenge. This article develops a sound model of the lateral transport of suspended sediment in environmental fluid flows such as floods and tsunamis. The model is systematically derived from a 3D turbulence model based on the Smagorinski large eddy closure. Embedding the physical dynamics into a family of problems and analysing linear dynamics of the system, centre manifold theory indicates the existence of slow manifold parametrised by macroscale variables. Computer algebra then constructs the slow manifold in terms of fluid depth, depth-averaged lateral velocities, and suspended sediment concentration. The model includes the effects of sediment erosion, advection, dispersion, and also the interactions between the sediment and turbulent fluid flow. Vertical distributions of the velocity and concentration in steady flow agree with the established experimental data. Numerical simulations of the suspended sediment under large waves show that ...

Cao, Meng

2014-01-01T23:59:59.000Z

307

Universal equations and constants of turbulent motion  

E-Print Network [OSTI]

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

Baumert, Helmut Z

2012-01-01T23:59:59.000Z

308

Experimental Investigations of Mixing?Processes in The Wake of A Circular Cylinder in Stratified Flows  

Science Journals Connector (OSTI)

The existence of oxygen?rich saltwater in the deeper basins of the Baltic Sea is mainly caused by sporadic inflow?events of salty and oxygen?rich saltwater from the North Sea into the Baltic Sea. These inflows take place over the narrow and shallow Drogden Sill into the first basin the Arkona Sea. Actually different offshore wind farms are planned in this region which opens a whole string of questions about the ecological influence of offshore wind farms on the mixing of both layers. To answer these questions numerical simulations of the mixing processes in the wake of wind turbine bases have been carried out. For the evaluation and quantification of these mixing processes a laboratory?experiment with a simplified model of the natural configuration has been realized. For this purpose a new water?channel has been build. This channel allows to simulate the inflow of saltwater in a size?scale of 1:100 to reality by keeping the densimetric Froude?Number. The experimental configuration consists of a long circular cylinder with a diameter of 8 cm in a 10 cm thick saltwater?layer flowing under a stationary fresh?water layer of 30 cm thickness. Focus point of this investigation is the wake of the cylinder in the stratified flow and the mixing?processes in the shear?layer due to the influence of the cylinder. The stratified flow around the cylinder induces the typical Karman?vortex wake horseshoe?vortices at the bottom and in the shear layer and Kelvin?Helmholtz?instabilities in the shear?layer. Nonintrusive optical measurements were taken with planar laser?induced fluorescence (PLIF) combined with two dimensional particle imaging velocimetry (PIV). The combination of both techniques allows the determination of instantaneous velocity components u and w from PIV?measurements the salinity s from PLIF?experiments their variations u? w? s? and the correlations of those like Reynolds?stress terms (u?u? u?w? w?w?) and turbulent? or Reynolds?flux terms (w?s? u?s?). Especially the vertical Reynolds?flux w?s? is the characteristic parameter to evaluate entrainment?velocity and entrainment?coefficient.

Peter Menzel; Frank Hüttmann; Martin Brede; Alfred Leder

2007-01-01T23:59:59.000Z

309

The dynamics of variable-density turbulence  

SciTech Connect (OSTI)

The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field, is in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations. In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For the case of buoyancy-generated turbulence, variable-density departures from the Boussinesq approximation are studied. The results of the buoyancy-generated turbulence are compared with variable-density model predictions. Both a one-point (engineering) model and a two-point (spectral) model are tested against the numerical data. Some deficiencies in these variable-density models are discussed and modifications are suggested.

Sandoval, D.L.

1995-11-01T23:59:59.000Z

310

The JET Project: Introduction and Background  

Science Journals Connector (OSTI)

...magnetic confinement of high-temperature plasma in conditions close to those needed for energy-producing controlled thermonuclear fusion reactors. Physically, JET is a very powerful toroidalpinch electric discharge in a strong stabilizing magnetic...

1987-01-01T23:59:59.000Z

311

Viscosity and jet quenching from holographic model  

E-Print Network [OSTI]

We consider the backreaction of the fundamental flavor degrees of freedom on the AdS$_5$-Schwarz background, and calculate their contributions to the shear viscosity and jet-quenching parameter of the thermal quark-gluon plasma.

Yi-hong Gao; Wei-shui Xu; Ding-fang Zeng

2007-07-05T23:59:59.000Z

312

Feasibility Study for a New Business Jet  

E-Print Network [OSTI]

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

Mousa, Yasser Abdullah

2009-05-15T23:59:59.000Z

313

Inclusive jet cross section at CDF  

SciTech Connect (OSTI)

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

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

2005-01-01T23:59:59.000Z

314

MULTIWAVELENGTH OBSERVATIONS OF THE SS 433 JETS  

E-Print Network [OSTI]

We present observations of the SS 433 jets using the Chandra High Energy Transmission Grating Spectrometer with contemporaneous optical and Very Long Baseline Array observations. The X-ray and optical emission line regions ...

Canizares, Claude R.

315

The JET Project: Introduction and Background  

Science Journals Connector (OSTI)

...confinement of high-temperature plasma in conditions close to those needed for energy-producing controlled thermonuclear fusion reactors. Physically, JET is a very powerful toroidalpinch electric discharge in a strong stabilizing magnetic...

1987-01-01T23:59:59.000Z

316

Electron Thermal Transport in Tokamak: ETG or TEM Turbulences?  

E-Print Network [OSTI]

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

Zonca, Fulvio

317

Numerical Tokamak Turbulence calculations on the CRAY T3E  

Science Journals Connector (OSTI)

Full cross section calculations of ion-temperature-gradient-driven turbulence with Landau closure are being carried out as part of the Numerical Tokamak Turbulence Project, one of the U. S. Department of Energy's Phase II Grand Challenges. To include ... Keywords: PVM, fusion energy, parallel computing, t3e, turbulence

V. E. Lynch; J-N. Leboeuf; B. A. Carreras; J. D. Alvarez; L. Garcia

1997-11-01T23:59:59.000Z

318

Gyro-water-bag approach in nonlinear gyrokinetic turbulence  

Science Journals Connector (OSTI)

Turbulent transport is a key issue for controlled thermonuclear fusion based on magnetic confinement. The thermal confinement of a magnetized fusion plasma is essentially determined by the turbulent heat conduction across the equilibrium magnetic field. ... Keywords: 65M15, 65P40, 83C05, Discontinuous Galerkin methods, Gyrokinetic equations, Plasma turbulence, Quasilinear theory, Semi-Lagrangian methods, Water-bag model

Nicolas Besse; Pierre Bertrand

2009-06-01T23:59:59.000Z

319

Detailed structure of spinning detonation in a circular tube  

SciTech Connect (OSTI)

A single spinning detonation wave propagating in a circular tube, discovered experimentally in 1926, is simulated three-dimensionally with a detailed chemical reaction mechanism. The detonation front obtained numerically rotates periodically with a Mach leg, whiskers, and a transverse detonation. A long pressure trail, which is distributed from the transverse detonation to downstream, was reproduced, clearly showing that the pressure trail also spins synchronously with the transverse detonation. The formation of an unburned gas pocket behind the detonation front was not observed in the present simulations because the rotating transverse detonation completely consumed the unburned gas. The calculated profiles of instantaneous OH mass fraction have a keystone shape behind the detonation front. The numerical results for pitch, track angle, Mach stem angle, and incident shock angle on the tube wall agree well with the experimental results. (author)

Tsuboi, N. [Space Transportation Engineering Department, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510 (Japan); Eto, K.; Hayashi, A.K. [Department of Mechanical Engineering, Aoyama Gakuin University, Fuchinobe 5-10-1, Sagamihara, Kanagawa 229-8558 (Japan)

2007-04-15T23:59:59.000Z

320

Large-amplitude circularly polarized electromagnetic waves in magnetized plasma  

SciTech Connect (OSTI)

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

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

2014-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Federal Acquisition Regulations Federal Acquisition Circular 2005-51 Summary  

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

Regulations Regulations Federal Acquisition Circular 2005-51 Summary Federal Register April 1, 2011 76FR 18304 I Women-Owned Small Business (WOSB) Program (Interim Rule). II Clarification of Standard Form 26--Award/Contract. Item I--Women-Owned Small Business (WOSB) Program (FAR Case 2010-015) (Interim) This interim rule amends the FAR to add subpart 19.15, Women-Owned Small Business Program, which will assist Federal agencies in achieving the 5 percent statutory goal for contracting with women-owned small business (WOSB) concerns. Agencies may restrict competition to economically disadvantaged women-owned small business (EDWOSB) concerns for contracts assigned a North American Industry Classification Systems (NAICS) code in an industry in which the Small Business Administration has

322

On the Radiation of Sound from an Unflanged Circular Pipe  

Science Journals Connector (OSTI)

A rigorous and explicit solution is obtained for the problem of sound radiation from an unflanged circular pipe, assuming axially symmetric excitation. The solution is valid throughout the wave-length range of dominant mode (plane wave) propagation in the pipe. The reflection coefficient for the velocity potential within the pipe and the power-gain function, embodying the characteristics of the radiation pattern, are evaluated numerically. The absorption cross section of the pipe for a plane wave incident from external space, and the gain function for this direction, are found to satisfy a reciprocity relation. In particular, the absorption cross section for normal incidence is just the area of the mouth. At low frequencies of vibration, the velocity potential within the pipe is the same as if the pipe were lengthened by a certain fraction of the radius and the open end behaved as a loop. The exact value of the end correction turns out to be 0.6133.

Harold Levine and Julian Schwinger

1948-02-15T23:59:59.000Z

323

New results on jet fragmentation at CDF  

SciTech Connect (OSTI)

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

Jindariani, Sergo; /Florida U.

2006-12-01T23:59:59.000Z

324

Measuring collinear W emissions inside jets  

E-Print Network [OSTI]

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

Frank Krauss; Petar Petrov; Marek Schoenherr; Michael Spannowsky

2014-03-19T23:59:59.000Z

325

Gap between jets at the LHC  

SciTech Connect (OSTI)

We describe a NLL BFKL calculation implemented in the HERWIG MC of the gap between jets cross section, that represent a test of BFKL dynamics. We compare the predictions with recent measurements at the Tevatron and present predictions for the LHC. We also discuss the interesting process of looking for gap between jets in diffractive events when protons are detected in the ATLAS Forward Physics (AFP) detectors.

Royon, Christophe [CEA/IRFU/Service de physique des particules, CEA/Saclay, 91191 Gif-sur-Yvette cedex (France)

2013-04-15T23:59:59.000Z

326

Protein Characterisation by Synchrotron Radiation Circular Dichroism (SRCD) Spectroscopy  

SciTech Connect (OSTI)

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

Wallace, B.

2009-01-01T23:59:59.000Z

327

Probing nuclear matter with jet conversions  

SciTech Connect (OSTI)

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 p{sub T}. In particular, quantum chromodynamics (QCD) jets coupling to a chemically equilibrated quark gluon plasma in nuclear collisions will lead to hadron ratios at high transverse momentum p{sub T} that can differ significantly from their counterparts in p+p collisions. Flavor measurements could complement energy loss as a way to study interactions of hard QCD jets with nuclear matter. Roughly speaking they probe the inverse mean free path 1/{lambda} while energy loss probes the average squared momentum transfer {mu}{sup 2}/{lambda}. We present some estimates for the rate of jet conversions in a consistent Fokker-Planck framework and their impact on future high-p{sub T} identified hadron measurements at RHIC and LHC. We also suggest some novel observables to test flavor effects.

Liu, W. [Cyclotron Institute and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Fries, R. J. [Cyclotron Institute and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2008-05-15T23:59:59.000Z

328

The Infrared Jet in 3C31  

E-Print Network [OSTI]

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

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

2015-01-01T23:59:59.000Z

329

The writhing of circular cross–section rods: undersea cables to DNA supercoils  

Science Journals Connector (OSTI)

...circular cross-section rods: undersea cables to DNA supercoils D. M. Stump 1 W...tension and torque, such as undersea cables, and to closed loops with inserted twist...circular cross-section rods: undersea cables to DNA supercoils By D. M. Stump1...

1998-01-01T23:59:59.000Z

330

ATLAS jet and missing-ET reconstruction, calibration, and performance  

E-Print Network [OSTI]

The ATLAS experiment has achieved a very high precision on jet and missing transverse energy performance by the use of advanced calorimeter-based topological clustering and local cluster calibration, event-by-event pile-up subtraction methods, and in situ techniques to correct for the residual jet energy response difference between data and simulation. Tracking information is being combined with calorimeter to further improve the jet and missing transverse energy performance. ATLAS has also commissioned several new powerful tools for the analysis and interpretation of hadronic final states at the LHC such as jet substructure, jet mass, quark-gluon discrimination, and jet tagging tools for the identification of boosted heavy particles. An overview of the reconstruction, calibration, and performance of jets, missing transverse energy, jet substructure, and jet tagging at ATLAS is presented.

Berta, P; The ATLAS collaboration

2014-01-01T23:59:59.000Z

331

A turbulence model for buoyant flows based on vorticity generation.  

SciTech Connect (OSTI)

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

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

2005-10-01T23:59:59.000Z

332

Atmospheric-pressure plasma jet  

SciTech Connect (OSTI)

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 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 there between. 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.

Selwyn, G.S.

1999-10-05T23:59:59.000Z

333

PHOTOSPHERIC EMISSION FROM STRATIFIED JETS  

SciTech Connect (OSTI)

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

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

2013-11-01T23:59:59.000Z

334

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

E-Print Network [OSTI]

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

Boughezal, Radja; Liu, Xiaohui

2015-01-01T23:59:59.000Z

335

Colloidal particle deposition in turbulent flow  

SciTech Connect (OSTI)

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

Morton, D.S.

1994-05-01T23:59:59.000Z

336

6 Scalar Turbulence within the Canopy Sublayer  

E-Print Network [OSTI]

Engineering, University of Brasilia, Brazil 4 Department of Hydraulics, Transport and Civil Infrastructure changes in turbulent kinetic energy dissipation rate inside canopies, the relative importance of ejections the canopy are presented. Finally, the origin of organized eddy structure connected with surface renewal

Katul, Gabriel

337

Simulation Strategies for Shock-Turbulence Interactions  

SciTech Connect (OSTI)

The computational challenge of predicting shock-turbulence interactions stems from the fundamentally different physics at play. Shock waves are microscopically thin regions wherein flow properties change rapidly over a distance roughly equal to the molecular mean free path; hence, they are essentially strong discontinuities in the flow field. Turbulence, on the other hand, is a chaotic phenomenon with broadband spatial and temporal scales of motion. Most shock-capturing methods rely on strong numerical dissipation to artificially smooth the discontinuity, such that it can be resolved on the computational grid. Unfortunately, the artificial dissipation necessary for capturing shocks has a deleterious effect on turbulence. An additional problem is the fact that shock-capturing schemes are typically based on one-dimensional Riemann solutions that are not strictly valid in multiple dimensions. This can lead to anisotropy errors and grid-seeded perturbations. Other complications arising from upwinding, flux limiting, operator splitting etc., can seriously degrade performance and generate significant errors, especially in multiple dimensions. The purpose of this work is to design improved algorithms, capable of capturing both shocks and turbulence, which also scale to tens of thousands of processors. We have evaluated two new hydrodynamic algorithms, in relation to the widely used WENO method, on a suite of test cases. The new methods, referred to as the 'Compact' and 'Hybrid' schemes, show very promising results.

Cook, A; Larsson, J; Cabot, W; Lele, S K

2008-02-20T23:59:59.000Z

338

Turbulent drag reduction through oscillating discs  

E-Print Network [OSTI]

The changes of a turbulent channel flow subjected to oscillations of wall flush-mounted rigid discs are studied by means of direct numerical simulations. The Reynolds number is $R_\\tau$=$180$, based on the friction velocity of the stationary-wall case and the half channel height. The primary effect of the wall forcing is the sustained reduction of wall-shear stress, which reaches a maximum of 20%. A parametric study on the disc diameter, maximum tip velocity, and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag reduction and maximum net energy saving, computed by taking into account the power spent to actuate the discs. This may be positive and reaches 6%. The Rosenblat viscous pump flow is used to predict the power spent for disc motion in the turbulent channel flow and to estimate localized and transient regions over the disc surface subjected to the turbulent regenerative braking effect, for which the wall turbulence exerts work on the discs. The...

Wise, Daniel J

2014-01-01T23:59:59.000Z

339

CHAPTER ____ THE AIR-WATER INTERFACE: TURBULENCE  

E-Print Network [OSTI]

.g. from paper mills. The desorption of dissolved substances, like PCBs, from inland and coastal water at an unsheared air-water interface, i.e., a situation in which the winds are light and the fluid motions category, we consider situations with significant wind shear at the surface. In this case, the turbulence

California at Santa Barbara, University of

340

Direct numerical simulation of turbulent mixing  

Science Journals Connector (OSTI)

...in-[5]. The low-cost approach to turbulence...growing with n. The graphs corresponding to these...rates-both chemical and nuclear. The same is true for...Figure-17 shows the graph of the TMZ boundary dependence...of providing safety in nuclear power production facilities...

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Global invariants in ideal magnetohydrodynamic turbulence  

SciTech Connect (OSTI)

Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.

Shebalin, John V. [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)] [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)

2013-10-15T23:59:59.000Z

342

Comparison of anemometers for turbulence characterization  

SciTech Connect (OSTI)

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

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

1992-10-01T23:59:59.000Z

343

AMBIPOLAR DIFFUSION HEATING IN TURBULENT SYSTEMS  

SciTech Connect (OSTI)

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

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

2012-11-20T23:59:59.000Z

344

On Challenges for Hypersonic Turbulent Simulations  

SciTech Connect (OSTI)

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

Yee, H C; Sjogreen, B

2009-01-14T23:59:59.000Z

345

Asymptotic scaling in turbulent pipe flow  

Science Journals Connector (OSTI)

...obtained in industrial piping such as a transcontinental natural gas pipelines. D is the pipe diameter and is the volume-averaged...Marati, N , C.M Casciola, and R Piva2004Energy cascade and spatial fluxes in wall turbulence. J. Fluid Mech...

2007-01-01T23:59:59.000Z

346

Supersonic Hydrodynamic Turbulence 1 Alexei Kritsuk  

E-Print Network [OSTI]

gas turbulence is known not to have an isotropic or homogeneous nature. Therefore, we can draw cascade Summary References: Kritsuk, Norman, & Padoan, ApJL 638, L25, 2006 Kritsuk, Wagner, Norman) 1895 Reynolds ("Reynolds decomposition", "Reynolds equation") 1922 Richardson ("Richardson cascade

Kritsuk, Alexei

347

6, 52515268, 2006 Turbulent fluxes over  

E-Print Network [OSTI]

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

Boyer, Edmond

348

Coherence in Chaos and Caviton Turbulence  

Science Journals Connector (OSTI)

The chaotic nature of "caviton turbulence" is studied in one-dimensional, many-Fourier-mode numerical simulations of the driven dissipative Zakharov equations. Above the modulational instability threshold the system evolves into a variety of stable patterns of cavitons which become chaotic for stronger driving. The cavitons remain coherent for times long compared to the shortest Lyapunov time.

G. D. Doolen; D. F. DuBois; H. A. Rose; B. Hafizi

1983-08-01T23:59:59.000Z

349

Cup Anemometer Behavior in Turbulent Environments  

Science Journals Connector (OSTI)

The behavior of the cup anemometer rotor in turbulent atmospheric flow is discussed in terms of a general equation of motion. This equates the rate of change s?? of the rotation rate s? of the rotor to a forcing F(s?, h?, w?), which is proportional ...

Leif Kristensen

1998-02-01T23:59:59.000Z

350

Turbulence and cooling in galaxy cluster cores  

Science Journals Connector (OSTI)

......2012). Thus, in our models energy is deposited via homogeneous...turbulence, with mechanical energy input. To prevent catastrophic...Vazquez-Semadeni, Gazol Scalo 2000; Audit Hennebelle 2005). Our paper...et-al. (2010), the feedback energy was directly added to internal......

Nilanjan Banerjee; Prateek Sharma

2014-01-01T23:59:59.000Z

351

SEGMENTATION INDEPENDENT ESTIMATES OF TURBULENCE PARAMETERS  

E-Print Network [OSTI]

SEGMENTATION INDEPENDENT ESTIMATES OF TURBULENCE PARAMETERS G. C. Papanicolaoua, K. Solnab and D, University of Utah, Salt Lake City, UT 84112 cPhillips Laboratory, Kirtland AFB, NM 87117 ABSTRACT We present of the detail coe cients at scale j. The spectrum can therefore be interpreted as representing the energy

Papanicolaou, George C.

352

OF HEALTH CARE IN TURBULENT TIMES  

E-Print Network [OSTI]

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

Feschotte, Cedric

353

Universal constants and equations of turbulent motion  

E-Print Network [OSTI]

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

Baumert, Helmut Z

2011-01-01T23:59:59.000Z

354

Helicity within the Kolmogorov phenomenology of turbulence  

E-Print Network [OSTI]

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

Kurien, Susan

355

Compressible Turbulence and Interactions with Shock Waves and Material  

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

Compressible Turbulence Compressible Turbulence and Interactions with Shock Waves and Material Interfaces Compressible Turbulence and Interactions with Shock Waves and Material Interfaces Lele.jpg Alternate Title: High-fidelity simulations of supersonic turbulent mixing and combustion Key Challenges: Direct numerical simulation (DNS) of isotropic turbulence interacting with a normal shock wave and turbulent multi-material mixing in the Richtmyer-Meshkov instability (RMI) Why it Matters: Shock/turbulence interaction is a fundamental phenomenon in fluid mechanics that occurs in a wide range of interesting problems in various disciplines, including supernova explosions, inertial confinement fusion, hypersonic flight and propulsion, and shock wave lithotripsy. Accomplishments: A novel solution-adaptive algorithm that applies different

356

Petascale Direct Numerical Simulations of Turbulent Channel Flow  

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

Petascale Petascale Direct Numerical Simulations of Turbulent Channel Flow MyoungKyu Lee mk@ices.utexas.edu Department of Mechanical Engineering University of Texas at Austin ESP Meeting May, 2013 M.K. Lee (Univ of Texas, Austin) Petascale DNS of Turbulent Channel Flow ESP Meeting May, 2013 1 / 30 Contents Project Overview Performance Optimization Early Result Conclusion M.K. Lee (Univ of Texas, Austin) Petascale DNS of Turbulent Channel Flow ESP Meeting May, 2013 2 / 30 Project Overview Project Title ◮ Petascale Direct Numerical Simulations of Turbulent Channel Flow Goal ◮ Expanding our understand of wall-bounded turbulence Personnel ◮ P.I. : Robert Moser ◮ Primary Developer : M.K.Lee ◮ Software Engineering Support : Nicholas Malaya ◮ Catalyst : Ramesh Balakrishnan M.K. Lee (Univ of Texas, Austin) Petascale DNS of Turbulent Channel Flow ESP Meeting May, 2013 3 / 30 Turbulent

357

A Dynamical Model of Plasma Turbulence in the Solar Wind  

E-Print Network [OSTI]

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

Howes, G G

2015-01-01T23:59:59.000Z

358

Assessment of reduced mechanisms using One Dimensional Stochastic Turbulence model  

E-Print Network [OSTI]

syngas jet flame. Proceeding of Fall 2009 Technical Meeting of the Western States Section of the Combustion

Chien, Li-Chun

2010-01-01T23:59:59.000Z

359

MULTIWAVELENGTH OBSERVATIONS OF THE SS 433 JETS  

SciTech Connect (OSTI)

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

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

2013-09-20T23:59:59.000Z

360

A Search for Jet Handedness in Hadronic $Z^0$ Decays  

E-Print Network [OSTI]

We have searched for signatures of polarization in hadronic jets from $Z^0 \\to q \\bar{q}$ decays using the ``jet handedness'' method. The polar angle asymmetry induced by the high SLC electron-beam polarization was used to separate quark jets from antiquark jets, expected to be left- and right-polarized, respectively. We find no evidence for jet handedness in our global sample or in a sample of light quark jets and we set upper limits at the 95% C.L. of 0.063 and 0.099 respectively on the magnitude of the analyzing power of the method proposed by Efremov {\\it et al.}

K. Abe

1995-01-13T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

PERPENDICULAR ION HEATING BY REDUCED MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect (OSTI)

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

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

2013-10-20T23:59:59.000Z

362

Journal of Turbulence Volume 7, No. 73, 2006  

E-Print Network [OSTI]

streams is desired. In small-scale combustors such as micro gas turbines, mixing enhancement between fuel of the inner jet. Unlike in the natural jet, streamwise vortices appear in the inner shear layer that the azimuthal wavelength under the present control scheme is almost the same as that of the natural jet

Tokyo, University of

363

Concentration Distributions during Pulse Jet Mixing  

SciTech Connect (OSTI)

Obtaining real-time, in situ slurry concentration measurements during unsteady mixing can provide increased understanding into mixer performance. During recent tests an ultrasonic attenuation sensor was inserted into a mixing vessel to measure the slurry concentration during unsteady mixing in real time during pulse jet mixer operation. These pulse jet mixing tests to suspend noncohesive solids in Newtonian liquid were conducted at three geometric scales. To understand the solids suspension process and resulting solids distribution, the concentration of solids in the cloud was measured at various elevations and radial positions during the pulse jet mixer cycle. In the largest scale vessel, concentration profiles were measured at three radial locations: r = 0, 0.5 and 0.9 R where R is the vessel radius. These radial concentration data are being analyzed to provide a model for predicting concentration as a function of elevation. This paper describes pulse jet mixer operation, provides a description of the concentration probe, and presents transient concentration data obtained at three radial positions: in the vessel center (O R), midway between the center and the wall (0.5 R) and near the vessel wall (0.9 R) through out the pulse to provide insight into pulse jet mixer performance.

Bamberger, Judith A.; Meyer, Perry A.

2010-08-05T23:59:59.000Z

364

The minimum jet power and equipartition  

E-Print Network [OSTI]

We derive the minimum power of jets and their magnetic field strength based on their observed non-thermal synchrotron emission. The correct form of this method takes into account both the internal energy in the jet and the ion rest-mass energy associated with the bulk motion. The latter was neglected in a number of papers, which instead adopted the well-known energy-content minimization method. That method was developed for static sources, for which there is no bulk-motion component of the energy. In the case of electron power-law spectra with index >2 in ion-electron jets, the rest-mass component dominates. The minimization method for the jet power taking it into account was considered in some other work, but only based on either an assumption of a constant total synchrotron flux or a fixed range of the Lorentz factors. Instead, we base our method on an observed optically-thin synchrotron spectrum. We find the minimum jet power is independent of its radius when the rest-mass power dominates, which becomes th...

Zdziarski, Andrzej A

2014-01-01T23:59:59.000Z

365

A Study of Vertical Gas Jets in a Bubbling Fluidized Bed  

SciTech Connect (OSTI)

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

Steven Ceccio; Jennifer Curtis

2011-01-18T23:59:59.000Z

366

Large-eddy simulations of impinging over-expanded supersonic jet noise for launcher applications  

Science Journals Connector (OSTI)

During the lift-off phase of a space launcher powerful rocket motors generate harsh acoustic environment on the launch pad. Following the blast waves created at ignition jet noise is a major contributor to the acoustic loads received by the launcher and its payload. Recent simulations performed at ONERA to compute the noise emitted by solid rocket motors at lift-off conditions are described. Far-field noise prediction is achieved by associating a LES solution of the jet flow with an acoustics surface integral method. The computations are carried out with in-house codes CEDRE for the LES solution and KIM for Ffowcs Williams & Hawkings porous surface integration method. The test case is that of a gas generator fired vertically onto a 45 degrees inclined flat plate which impingement point is located 10 diameters from nozzle exit. Computations are run for varied numerical conditions such as turbulence modeling along the plate and different porous surfaces location and type. Results are discussed and compared with experimental acoustic measurements obtained by CNES at MARTEL facility.

2014-01-01T23:59:59.000Z

367

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

E-Print Network [OSTI]

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

368

Circular Higgs Factories & Possible Long-Term Strategy  

E-Print Network [OSTI]

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

Zimmermann, F

2013-01-01T23:59:59.000Z

369

Simulation on Buildup of Electron Cloud in Proton Circular Accelerator  

E-Print Network [OSTI]

Electron cloud interaction with high energy positive beam are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerator. An important uncertainty in predicting electron cloud instability lies in the detail processes on the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron cloud. China Spallation Neutron Source (CSNS) is the largest scientific project in building, whose accelerator complex includes two main parts: an H- linac and a rapid cycling synchrotron (RCS). The RCS accumulates the 80Mev proton beam and accelerates it to 1.6GeV with a repetition rate 25Hz. During the beam injection with lower energy, the emerging electron cloud may cause a serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up, distribution and dens...

Liu, Yu-Dong

2014-01-01T23:59:59.000Z

370

HEFA and Fischer-Tropsch Jet Fuel Cost Analyses | Department...  

Energy Savers [EERE]

HEFA and Fischer-Tropsch Jet Fuel Cost Analyses HEFA and Fischer-Tropsch Jet Fuel Cost Analyses This is a presentation from the November 27, 2012, Sustainable Alternative Fuels...

371

Images in Emergency Medicine: Irritant Contact Dermatitis from Jet Fuel  

E-Print Network [OSTI]

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

Trigger, Christopher C; Eilbert, Wesley

2009-01-01T23:59:59.000Z

372

A study of the self-oscillating jet impingement nozzle  

E-Print Network [OSTI]

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

Chinnock, Paul Scott

1993-01-01T23:59:59.000Z

373

Applications of Underexpanded Jets in Hypersonic Aerothermodynamics Research  

E-Print Network [OSTI]

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

Riabov, Vladimir V.

374

ATLAS jet and missing ET reconstruction, calibration, and performance  

E-Print Network [OSTI]

ATLAS has achieved a very high precision on jet and missing transverse energy performance by the use of advanced calorimeter-based topological clustering and local cluster calibration, event-by-event pile-up subtraction methods, and in situ techniques to correct for the residual jet energy response difference between data and simulation. Tracking information is being combined with calorimeter to further improve the jet and missing ET performance. ATLAS has also commissioned several new powerful tools for for the analysis and interpretation of hadronic final states at the LHC such as jet substructure, jet mass, quark-gluon discrimination, and jet tagging tools for the identification of boosted heavy particles. An overview of the reconstruction, calibration and performance of jets, missing ET, and jet substructure and tagging at ATLAS is presented.

Crispin Ortuzar, M; The ATLAS collaboration

2014-01-01T23:59:59.000Z

375

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

E-Print Network [OSTI]

to the injection wall are considered. These studies develop a strategy for control based on separate experimental engines, dilution jet injection in gas turbine combustors, thrust vectoring jets, and turbine blade film

M'Closkey, Robert T.

376

Active noise control of supersonic impinging jet using pulsed microjets  

E-Print Network [OSTI]

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

Hong, Seung Hyuck

2009-01-01T23:59:59.000Z

377

Feedback control of flow separation using synthetic jets  

E-Print Network [OSTI]

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

Kim, Kihwan

2006-04-12T23:59:59.000Z

378

Mixing enhancement by use of swirling jets  

SciTech Connect (OSTI)

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

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

1993-01-01T23:59:59.000Z

379

Constraints from jet calculus on quark recombination  

Science Journals Connector (OSTI)

Within the quantum-chromodynamic jet-calculus formalism, we deduce an equation describing recombination of quarks and antiquarks into mesons within a quark or gluon jet. This equation relates the recombination function R(x1,x2,x) used in current literature to the fragmentation function for producing that same meson out of the parton initiating the jet. We submit currently used recombination functions to our consistency test, taking as input mainly the u-quark fragmentation "data" into ?+ mesons. The qq¯?? recombination functions popular in the literature are consistent with measured fragmentation functions, but they must be supplemented by other contributions to provide the full Du?+. We also discuss the Q2 dependence of the resulting fragmentation functions.

L. M. Jones; K. E. Lassila; U. Sukhatme; D. Willen

1981-02-01T23:59:59.000Z

380

3-D GRMHD Simulations of Generating Jets  

E-Print Network [OSTI]

We have performed a first fully 3-D GRMHD simulation with Schwarzschild black hole with a free falling corona. The initial simulation results show that a jet is created as in the previous simulations using the axisymmetric geometry with the mirror symmetry at the equator. However, the time to generate the jet is longer than in the 2-D axisymmetric simulations. We expect that due to the additional freedom in the azimuthal dimension without axisymmetry with respect to the z axis and reflection symmetry with respect to the equatorial plane, the dynamics of jet formation can be modified. Further simulations are required for the study of instabilities along the azimuthal direction such as accretion-eject instability

Nishikawa, K I; Shibata, K; Kudoh, T; Sol, H

2002-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

3-D GRMHD Simulations of Generating Jets  

E-Print Network [OSTI]

We have performed a first fully 3-D GRMHD simulation with Schwarzschild black hole with a free falling corona. The initial simulation results show that a jet is created as in the previous simulations using the axisymmetric geometry with the mirror symmetry at the equator. However, the time to generate the jet is longer than in the 2-D axisymmetric simulations. We expect that due to the additional freedom in the azimuthal dimension without axisymmetry with respect to the z axis and reflection symmetry with respect to the equatorial plane, the dynamics of jet formation can be modified. Further simulations are required for the study of instabilities along the azimuthal direction such as accretion-eject instability

K. -I. Nishikawa; S. Koide; K. Shibata; T. Kudoh; H. Sol

2002-08-05T23:59:59.000Z

382

On the Misalignment of Jets in Microquasars  

E-Print Network [OSTI]

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

Thomas J. Maccarone

2002-09-05T23:59:59.000Z

383

On the Counter-jet Emission in GRB Afterglows  

SciTech Connect (OSTI)

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

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

2010-10-15T23:59:59.000Z

384

IR diagnostics of embedded jets: velocity resolved observations of the HH34 and HH1 jets  

E-Print Network [OSTI]

We present VLT-ISAAC medium resolution spectroscopy of the HH34 and HH1 jets. Our aim is to derive the kinematics and the physical parameters and to study how they vary with jet velocity. We use several important diagnostic lines such as [FeII] 1.644um, 1.600um and H2 2.122um. In the inner jet region of HH34 we find that both the atomic and molecular gas present two components at high and low velocity. The [FeII] LVC in HH34 is detected up to large distances from the source (>1000 AU), at variance with TTauri jets. In H2 2.122um, the LVC and HVC are spatially separated. We detect, for the first time, the fainter red-shifted counterpart down to the central source. In HH1, we trace the jet down to ~1" from the VLA1 driving source: the kinematics of this inner region is again characterised by the presence of two velocity components, one blue-shifted and one red-shifted with respect to the source LSR velocity. In the inner HH34 jet region, ne increases with decreasing velocity. Up to ~10" from the driving source, and along the whole HH1 jet an opposite behaviour is observed instead, with ne increasing with velocity. In both jets the mass flux is carried mainly by the high-velocity gas. A comparison between the position velocity diagrams and derived electron densities with models for MHD jet launching mechanisms has been performed for HH34. While the kinematical characteristics of the line emission at the jet base can be, at least qualitatively, reproduced by both X-winds and disc-wind models, none of these models can explain the extent of the LVC and the dependence of electron density with velocity that we observe. It is possible that the LVC in HH34 represents gas not directly ejected in the jet but instead denser ambient gas entrained by the high velocity collimated jet.

R. Garcia Lopez; B. Nisini; T. Giannini; J. Eisloeffel; F. Bacciotti; L. Podio

2008-05-19T23:59:59.000Z

385

Heavy quarks in the jet calculus  

Science Journals Connector (OSTI)

In this paper we explore a method for treating heavy quarks such as c and b quarks within the jet calculus. These quarks are differentiated from the more common u, d, and s quarks by the requirement that the gluons never branch into heavy-quark pairs during the jet development. We compute and discuss the charmed-quark "propagators"; the x distribution of colorless clusters containing a charmed quark, a noncharmed antiquark, and gluons; and the mass distribution of the parent partons giving rise to these colorless clusters.

L. M. Jones

1983-07-01T23:59:59.000Z

386

Jet energy flow at the LHC  

Science Journals Connector (OSTI)

We present a quantitative study of energy flow away from jets by numerically solving the evolution equation derived by Banfi, Marchesini, and Smye, and apply the result to two processes at the LHC: discriminating high-pt jets originating from decays of heavy electroweak bosons from the QCD background, and the survival probability of the BFKL-initiated dijet rapidity gaps. As a by-product, we find a hidden symmetry of the Banfi, Marchesini, and Smye equation which is a remnant of conformal symmetry.

Yoshitaka Hatta and Takahiro Ueda

2009-10-19T23:59:59.000Z

387

Generalized Batchelor functions of isotropic turbulence  

E-Print Network [OSTI]

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

Gravanis, Elias

2015-01-01T23:59:59.000Z

388

Generalized entropies in a turbulent dynamo simulation  

Science Journals Connector (OSTI)

A simulation of hydromagnetic turbulence exhibiting dynamo action is employed to estimate the generalized entropies, Hq, from the distribution of moments of local expansion factors of material line elements. These generalized entropies can be used to characterize the dynamics of turbulence and of nonlinear dynamo action. The value of the metric entropy, H1, is comparable to the largest Lyapunov exponent describing the divergence of trajectories in phase space, which in turn is somewhat larger than the growth rate of the magnetic energy. The value of the topological entropy, H0, is similar to the conversion rate of kinetic to magnetic energy, but larger than the growth rate of the dynamo. This is in agreement with results stating that the growth rate of the kinematic dynamo is limited by the topological entropy. The dependence of Hq on q leads to a criterion from which we infer that the degree of intermittency in our particular system is weak.

Axel Brandenburg; Isaac Klapper; Jürgen Kurths

1995-11-01T23:59:59.000Z

389

Causality detection and turbulence in fusion plasmas  

E-Print Network [OSTI]

This work explores the potential of an information-theoretical causality detection method for unraveling the relation between fluctuating variables in complex nonlinear systems. The method is tested on some simple though nonlinear models, and guidelines for the choice of analysis parameters are established. Then, measurements from magnetically confined fusion plasmas are analyzed. The selected data bear relevance to the all-important spontaneous confinement transitions often observed in fusion plasmas, fundamental for the design of an economically attractive fusion reactor. It is shown how the present method is capable of clarifying the interaction between fluctuating quantities such as the turbulence amplitude, turbulent flux, and Zonal Flow amplitude, and uncovers several interactions that were missed by traditional methods.

van Milligen, B Ph; Ramisch, M; Estrada, T; Hidalgo, C; Alonso, A

2013-01-01T23:59:59.000Z

390

Gaseous Jets in Comet Hale-Bopp (1995 O1)  

Science Journals Connector (OSTI)

We report the identification of gas jets in comet Hale-Bopp in OH, NH, CN, C2 and C3. This is the first time OH and NH jets without an obvious optical dust jet counterpart have been identified in narrowband comet...

Susan M. Lederer; Humberto Campins; David J. Osip…

391

The dynamics of variable-density turbulence  

SciTech Connect (OSTI)

The dynamics of variable-density turbulent fluids are studied by direct numerical simulation. The flow is incompressible so that acoustic waves are decoupled from the problem, and implying that density is not a thermodynamic variable. Changes in density occur due to molecular mixing. The velocity field is, in general, divergent. A pseudo-spectral numerical technique is used to solve the equations of motion. Three-dimensional simulations are performed using a grid size of 128{sup 3} grid points. Two types of problems are studied: (1) the decay of isotropic, variable-density turbulence, and (2) buoyancy-generated turbulence in a fluid with large density fluctuations (such that the Boussinesq approximation is not valid). In the case of isotropic, variable-density turbulence, the overall statistical decay behavior, for the cases studied, is relatively unaffected by the presence of density variations when the initial density and velocity fields are statistically independent. The results for this case are in quantitative agreement with previous numerical and laboratory results. In this case, the initial density field has a bimodal probability density function (pdf) which evolves in time towards a Gaussian distribution. The pdf of the density field is symmetric about its mean value throughout its evolution. If the initial velocity and density fields are statistically dependent, however, the decay process is significantly affected by the density fluctuations. For this case, the pdf of the density becomes asymmetric about its mean value during the early stages of its evolution. It is argued that these asymmetries in the pdf of the density field are due to different entrainment rates, into the mixing region, that favor the high speed fluid.

Sandoval, D.L.

1995-11-01T23:59:59.000Z

392

Transport during Turbulent Heating in a Tokamak  

Science Journals Connector (OSTI)

A model for the University of Texas turbulent torus is described. The prediction of the model shows a strong skin effect, and is in agreement with the experimental data if one saturates the Buneman instability by using the electron-trapping condition and the ionsound instability by using the anomalous collision frequency ?A?10-5(TeTi)(uve)?pe, which correlates with ion tail formation. An interpretation of the laser-scattering temperature measurements is proposed.

P. L. Mascheroni

1977-07-25T23:59:59.000Z

393

Acceleration and vortex filaments in turbulence  

E-Print Network [OSTI]

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

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

2005-01-23T23:59:59.000Z

394

NONIDEAL MAGNETOHYDRODYNAMIC TURBULENT DECAY IN MOLECULAR CLOUDS  

SciTech Connect (OSTI)

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

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

2009-08-20T23:59:59.000Z

395

Universal constants and equations of turbulent motion  

E-Print Network [OSTI]

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

Helmut Z. Baumert

2011-07-25T23:59:59.000Z

396

Free energy balance in gyrokinetic turbulence  

SciTech Connect (OSTI)

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

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

2011-09-15T23:59:59.000Z

397

SPECTRAL AND INTERMITTENCY PROPERTIES OF RELATIVISTIC TURBULENCE  

SciTech Connect (OSTI)

High-resolution numerical simulations are utilized to examine isotropic turbulence in a compressible fluid when long-wavelength velocity fluctuations approach light speed. Spectral analysis reveals an inertial sub-range of relativistic motions with a broadly 5/3 index. The use of generalized Lorentz covariant structure functions based on the four-velocity is proposed. These structure functions extend the She-Leveque model for intermittency into the relativistic regime.

Zrake, Jonathan; MacFadyen, Andrew I. [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

2013-01-20T23:59:59.000Z

398

On specification of initial conditions in turbulence models  

SciTech Connect (OSTI)

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

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

2010-12-01T23:59:59.000Z

399

Phenomenology of Wall Bounded Newtonian Turbulence  

E-Print Network [OSTI]

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

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

2005-06-28T23:59:59.000Z

400

Universal equations and constants of turbulent motion  

E-Print Network [OSTI]

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

Helmut Z. Baumert

2012-03-22T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

NUMERICAL SIMULATIONS OF DRIVEN RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect (OSTI)

A wide variety of astrophysical phenomena involve the flow of turbulent magnetized gas with relativistic velocity or energy density. Examples include gamma-ray bursts, active galactic nuclei, pulsars, magnetars, micro-quasars, merging neutron stars, X-ray binaries, some supernovae, and the early universe. In order to elucidate the basic properties of the relativistic magnetohydrodynamical (RMHD) turbulence present in these systems, we present results from numerical simulations of fully developed driven turbulence in a relativistically warm, weakly magnetized and mildly compressible ideal fluid. We have evolved the RMHD equations for many dynamical times on a uniform grid with 1024{sup 3} zones using a high-order Godunov code. We observe the growth of magnetic energy from a seed field through saturation at {approx}1% of the total fluid energy. We compute the power spectrum of velocity and density-weighted velocity U = {rho}{sup 1/3} v and conclude that the inertial scaling is consistent with a slope of -5/3. We compute the longitudinal and transverse velocity structure functions of order p up to 11 and discuss their possible deviation from the expected scaling for non-relativistic media. We also compute the scale-dependent distortion of coherent velocity structures with respect to the local magnetic field, finding a weaker scale dependence than is expected for incompressible non-relativistic flows with a strong mean field.

Zrake, Jonathan; MacFadyen, Andrew I. [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

2012-01-01T23:59:59.000Z

402

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

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

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

403

Induced chirality in fisetin upon binding to serum albumin: experimental circular dichroism and TDDFT calculations  

Science Journals Connector (OSTI)

Theoretical absorption and electronic circular dichroism (ECD) spectra predicted via time-dependent density functional theory (TDDFT) calculations on the neutral and four anionic species of fisetin, an achiral fl...

Iulia Matei; Sorana Ionescu; Mihaela Hillebrand

2012-09-01T23:59:59.000Z

404

Circular Dichroism Techniques for the Analysis of Intrinsically Disordered Proteins and Domains  

Science Journals Connector (OSTI)

Circular dichroism (CD) spectroscopy is a simple and powerful technique, which allows for the assessment of the conformational properties of a protein or protein domain. Intrinsically disordered proteins (IDPs), ...

Lucía B. Chemes; Leonardo G. Alonso…

2012-01-01T23:59:59.000Z

405

An Analysis of Depolarization of Circular Polarization in S-Band Radar Sensing of Alberta Storms  

Science Journals Connector (OSTI)

An analysis is given of storm events in 1982–85 in which the Alberta Research Council circularly polarized polarization diversity S-band radar recorded data indicating significant depolarization. The accompanying two-way differential propagation ...

Anthony R. Holt

2001-09-01T23:59:59.000Z

406

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

E-Print Network [OSTI]

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

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

407

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

E-Print Network [OSTI]

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

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

408

Travels of a floating space tool. A spacecraft is in a circular orbit ...  

E-Print Network [OSTI]

Travels of a floating space tool. A spacecraft is in a circular orbit 6750 km from the Earth's center of mass (i.e, it is about 250 miles above the surface).

2008-01-22T23:59:59.000Z

409

Measuring plasma turbulence using low coherence microwave radiation  

SciTech Connect (OSTI)

Low coherence backscattering (LCBS) is a proposed diagnostic technique for measuring plasma turbulence and fluctuations. LCBS is an adaptation of optical coherence tomography, a biomedical imaging technique. Calculations and simulations show LCBS measurements can achieve centimeter-scale spatial resolution using low coherence microwave radiation. LCBS measurements exhibit several advantages over standard plasma turbulence measurement techniques including immunity to spurious reflections and measurement access in hollow density profiles. Also, LCBS is scalable for 1-D profile measurements and 2-D turbulence imaging.

Smith, D. R. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-02-20T23:59:59.000Z

410

Turbulent Temperature Fluctuations in the Princeton Large Tokamak Plasma  

Science Journals Connector (OSTI)

We present the first experimental evidence for the existence of turbulent temperature fluctuations in plasmas. These measurements were accomplished by a spectral analysis of blackbody electron cyclotron emission. The fractional fluctuation in the mean electron energy is up to 10% for typical Princeton Large Tokamak discharges. The spectrum of temperature turbulence extends well beyond the electron diamagnetic-drift frequency f* and shows no resemblance to the simultaneously existing turbulent density fluctuations.

V. Arunasalam; R. Cano; J. C. Hosea; E. Mazzucato

1977-10-03T23:59:59.000Z

411

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

E-Print Network [OSTI]

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

Valasek, John

412

A Novel Jet Model: Magnetically Collimated, Radiation-Pressure Driven Jet  

Science Journals Connector (OSTI)

......reminiscent of nonradiative MHD jets (Lynden-Bell 1996...luminosity-hardness ratio diagram, and reported evolutionary paths in the diagram. More importantly, they found...Recent general-relativistic MHD simulations can indeed achieve......

Shun Takeuchi; Ken Ohsuga; Shin Mineshige

2010-10-25T23:59:59.000Z

413

Mechanism of current redistribution between jets in a double-jet electric arc  

Science Journals Connector (OSTI)

Characteristics of a double-jet electric arc have been determined by numerical simulation of ... plasma electrodes, along which the character of arc discharge changes from self-sustained to non-self-...

E. B. Kulumbaev; T. B. Nikulicheva

2013-01-01T23:59:59.000Z

414

HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS  

SciTech Connect (OSTI)

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

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

2009-04-20T23:59:59.000Z

415

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

E-Print Network [OSTI]

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

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

2000-02-15T23:59:59.000Z

416

Microsoft PowerPoint - Tokamak_turbulence3.pptx  

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

Plasma Physics Laboratory, Princeton U. d) U. California, Irvine Introduction * Tokamak confinement in the low confinement mode (L- mode) is dominated by turbulent...

417

Lattice Boltzmann simulations of decaying homogeneous isotropic turbulence  

Science Journals Connector (OSTI)

Decaying homogeneous isotropic turbulence in inertial and rotating reference frames is investigated to evaluate the capability of the lattice Boltzmann method in turbulence. In the inertial frame case, the decay exponents of kinetic energy and dissipation and the low wave-number scaling of the spectrum are studied. The results are in agreement with classical ones. In the frame-rotation case, simulations show that the energy decay rate decreases with decreasing Rossby number as the energy cascade is inhibited by rotation, again in agreement with turbulence physics. These results clearly indicate that the lattice Boltzmann method captures important features of decaying turbulence.

Huidan Yu; Sharath S. Girimaji; Li-Shi Luo

2005-01-25T23:59:59.000Z

418

Notes 09. Fluid inertia and turbulence in fluid film bearings  

E-Print Network [OSTI]

When fluid inertia effects are important. Bulk-flow model for inertial flows. Turbulence and inertia in short length journal bearings and open end dampers....

San Andres, Luis

2009-01-01T23:59:59.000Z

419

Modulation of homogeneous turbulence seeded with finite size ...  

E-Print Network [OSTI]

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

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

2010-01-30T23:59:59.000Z

420

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

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

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

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

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

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

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

422

JET PROPULSION LABORATORY 1979 Annual Report  

E-Print Network [OSTI]

, is the most active and complex volcanic body in our solar system and has a surface composed primarily of Technology and the National Aeronautics and Space Administration for the period January 1 to December 31 JPL Technology Institutional Activities JET PROPULSION LABORATORY California Institute of Technology

Waliser, Duane E.

423

Radio jets from stellar tidal disruptions  

Science Journals Connector (OSTI)

......nl A star that passes too close to a massive...time-dependent accretion rate. We apply this model...predict the snapshot rate of these events...accretion|black hole physics|galaxies: jets...predicted snapshot rate, we conclude that...lofar.org 3 www.physics.usyd.edu.au......

Sjoert van Velzen; Elmar Körding; Heino Falcke

2011-10-01T23:59:59.000Z

424

NLO Vector Boson Production With Light Jets  

SciTech Connect (OSTI)

In this contribution we present recent progress in the computation of next-to-leading order (NLO) QCD corrections for the production of an electroweak vector boson in association with jets at hadron colliders. We focus on results obtained using the virtual matrix element library BlackHat in conjunction with SHERPA, focusing on results relevant to understanding the background to top production. The production of a vector boson in association with several jets at the Large Hadron Collider (LHC) is an important background for other Standard Model processes as well as new physics signals. In particular, the production of a W boson in association with many jets is an important background for processes involving one or more top quarks. Precise predictions for the backgrounds are crucial to measurement of top-quark processes. Vector boson production in association with multiple jets is also a very important background for many SUSY searches, as it mimics the signatures of many typical decay chains. Here we will discuss how polarization information can be used as an additional handle to differentiate top pair production from 'prompt' W-boson production. More generally, ratios of observables, for example for events containing a W boson versus those containing a Z boson, are expected to be better-behaved as many uncertainties cancel in such ratios. Precise calculation of ratios, along with measurement of one of the two processes in the ratio, can be used in data-driven techniques for estimating backgrounds.

Bern, Z.; Diana, G.; Dixon, L.J.; Febres Cordero, F.; Forde, D.; Gleisberg, T.; Hoeche, S.; Ita, H.; Kosower, D.A.; Maitre, D.; Ozeren, K.

2012-02-15T23:59:59.000Z

425

Models comparison for JET polarimeter data  

SciTech Connect (OSTI)

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

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

2008-03-12T23:59:59.000Z

426

HOT ELECTROMAGNETIC OUTFLOWS. II. JET BREAKOUT  

SciTech Connect (OSTI)

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

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

2013-08-20T23:59:59.000Z

427

Exploring jet-launching conditions for SFXTs  

E-Print Network [OSTI]

In the magneto-centrifugal mechanism for jet formation, accreting neutron stars are assumed to produce relativistic jets only if their surface magnetic field is weak enough ($B \\sim 10^8$ G). However, the most common manifestation of neutron stars are pulsars, whose magnetic field distribution peaks at $B \\sim 10^{12}$ G. If the neutron star magnetic field has at least this strength at birth, it must decay considerably before jets can be launched in binary systems. We study the magnetic field evolution of a neutron star that accretes matter from the wind of a high-mass stellar companion so that we can constrain the accretion rate and the impurities in the crust, which are necessary conditions for jet formation. We solved the induction equation for the diffusion and convection of the neutron star magnetic field confined to the crust, assuming spherical accretion in a simpliflied one-dimensional treatment. We incorporated state-of-the-art microphysics, including consistent thermal evolution profiles, and assume...

García, Federico; Romero, Gustavo E

2014-01-01T23:59:59.000Z

428

The Rapidity Dependence of Jet Quenching  

E-Print Network [OSTI]

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

Thorsten Renk

2014-06-26T23:59:59.000Z

429

The interaction between two radial jets  

E-Print Network [OSTI]

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

Gruber, Thomas Clifton

2012-06-07T23:59:59.000Z

430

JET and the Prospect for Nuclear Fusion  

Science Journals Connector (OSTI)

This paper describes the Joint European Torus (JET) device which was built as a European collaboration effort, with the aim of testing the scientific feasibility of producing controlled thermonuclear reactions between light nuclei with a net yield of energy. JET is the largest magnetic confinement machine in the world both in physical size and in the magnitude of the plasma current (5 ? 106 Amperes). The machine came into operation in mid-1983 and has followed the first stages of a planned evolution, in which the performance is progressively increased mainly by adding more heating power and which will culminate in eventual operation in a deuterium-tritium mixture. This will permit study of the plasma performance when there is a substantial power input from the ?-particle fusion products. So far operating in deuterium gas with 8 MW of additional heating by neutral beams, a peak ion temperature of 12 keV has been obtained with a corresponding fusion product (density ? confinement time) of 8 ? 1018 m-3 s. If the same conditions were to be achieved in a deuterium-tritium mixture, then the ratio of thermonuclear power output to the heating power input, Q, would be ~ 0.1. It is expected that following further technical improvements to JET, "scientific breakthrough" (namely Q = 1) will be achieved. The next step after JET will be to study a burning or ignited plasma in which no power input is required because energy losses are balanced by ?-particle heating. The requirements for such an experiment will become increasingly clear as more data is obtained from JET. At present it seems likely that a larger apparatus will be needed with a plasma current capability of 12-15 MA. These requirements for the thermonuclear furnace remain broadly consistent with the known technological constraints on an eventual power reactor.

R J Bickerton

1988-01-01T23:59:59.000Z

431

Localized DLC etching by a non-thermal atmospheric-pressure helium plasma jet in ambient air  

Science Journals Connector (OSTI)

Abstract Using a versatile atmospheric-pressure helium plasma jet, diamond-like carbon (DLC) films were etched in ambient air. We observed that the DLC films are etched at a nominal rate of around 60 nm/min in the treated area (230 ?m in diameter) during a 20-min exposure. The etching rate increased after the initial 10-min exposure. During this period, the flat DLC surface was structurally modified to produce carbon nanostructures with a density of ~ 2.4 × 1011 cm? 2. With this increase in surface area, the etching rate increased. After 20 min, the DLC film had a circular pattern etched into it down to the substrate where silicon nanostructures were observed with sizes varying from 10 nm to 1 ?m. The initial carbon nanostructure formation is believed to involve selective removal of the sp2-bonded carbon domains. The carbon etching results from the formation of reactive oxygen species in the plasma.

Jun-Seok Oh; Yoshiaki Kakuta; Yuki Yasuoka; Hiroshi Furuta; Akimitsu Hatta

2014-01-01T23:59:59.000Z

432

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

E-Print Network [OSTI]

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

Janhunen, Salomon

2013-01-01T23:59:59.000Z

433

Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators  

SciTech Connect (OSTI)

The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC. Simulations studies and measurements were conducted that clearly show the correlation between RF noise and longitudinal bunch emittance, identify the major LLRF noise contributions, and determine the RF component dominating this effect. With these results, LHC upgrades and alternative algorithms are evaluated to reduce longitudinal emittance growth during operations. The applications of this work are described with regard to future machines and analysis of new technical implementations, as well as to possible future work which would continue the directions of this dissertation.

Mastoridis, Themistoklis; /Stanford U., Elect. Eng. Dept. /SLAC

2011-03-01T23:59:59.000Z

434

Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids  

E-Print Network [OSTI]

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

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

2008-05-30T23:59:59.000Z

435

The Temperature of Interstellar Clouds from Turbulent Heating  

E-Print Network [OSTI]

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

Liubin Pan; Paolo Padoan

2008-06-30T23:59:59.000Z

436

Thermal shallow water models of geostrophic turbulence in Jovian atmospheres  

SciTech Connect (OSTI)

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

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

2014-01-15T23:59:59.000Z

437

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

SciTech Connect (OSTI)

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

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

2005-06-01T23:59:59.000Z

438

THE ACCELERATING JET OF 3C 279  

SciTech Connect (OSTI)

Analysis of the proper motions of the subparsec scale jet of the quasar 3C 279 at 15 GHz with the Very Long Baseline Array shows significant accelerations in four of nine superluminal features. Analysis of these motions is combined with the analysis of flux density light curves to constrain values of Lorentz factor and viewing angle (and their derivatives) for each component. The data for each of these components are consistent with significant changes to the Lorentz factor, viewing angle, and azimuthal angle, suggesting jet bending with changes in speed. We see that for these observed components Lorentz factors are in the range {Gamma} = 10-41, viewing angles are in the range thetav = 0. Degree-Sign 1-5. Degree-Sign 0, and intrinsic (source frame) flux density is in the range, F{sub {nu},int} 1.5 Multiplication-Sign 10{sup -9}-1.5 Multiplication-Sign 10{sup -5} Jy. Considering individual components, the Lorentz factors vary from {Gamma} = 11-16 for C1, {Gamma} = 31-41 for C5, {Gamma} = 29-41 for C6, and {Gamma} = 9-12 for C8, indicating that there is no single underlying flow speed to the jet and likely we are seeing pattern speeds from shocks in the jet. The viewing angles vary in time from 0. Degree-Sign 6 to 1. Degree-Sign 5 in the case of C1 (the least extreme example), from 0. Degree-Sign 5 to 5. Degree-Sign 0 in the case of C8, and from 0. Degree-Sign 1 to 0. Degree-Sign 9 for C5 (the last two being the most extreme examples). The intrinsic flux density varies by factors from 1.4 for C8 and 430 for C5. Theoretical analysis of the accelerations also indicates potential jet bending. In addition, for one component, C5, polarization measurements also set limits to the trajectory of the jet.

Bloom, S. D. [Department of Physics and Astronomy, Hampden-Sydney College, Box 821, Hampden-Sydney, VA 23943 (United States); Fromm, C. M.; Ros, E., E-mail: sbloom@hsc.edu [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

2013-01-01T23:59:59.000Z

439

Feedback control of edge turbulence in a tokamak  

Science Journals Connector (OSTI)

An experiment on feedback control of edge turbulence has been undertaken on the KT-5C tokamak. The results indicate that the edge turbulence could be suppressed or enhanced depending on the phase shift of the feedback network. In a typical case of 90° phase shift feedback, the turbulence amplitudes of both T-tildee and ñe were reduced by about 25% when the gain of the feedback network was 15. Correspondingly the radial particle flux decreased to about 75% level of the background. Through bispectral analysis it is found that there exists a substantial nonlinear coupling between various modes comprised in edge turbulence, especially in the frequency range from about 10 kHz to 100 kHz, which contains the large part of the edge turbulence energy in KT-5C tokamak. In particular, by actively controlling the turbulence amplitude using feedback, a direct experimental evidence of the link between the nonlinear wave-wave coupling over the whole spectrum in turbulence, the saturated turbulence amplitude, and the radial particle flux was provided.

Zhai Kan; Wen Yi-zhi; Yu Chang-xuan; Liu Wan-dong; Wang Chao; Zhuang Ge; Xu Zhi-zhan

1997-03-01T23:59:59.000Z

440

DNS of Detonation Wave and Isotropic Turbulence Interaction  

E-Print Network [OSTI]

DNS of Detonation Wave and Isotropic Turbulence Interaction Hari Narayanan Nagarajan , Luca Massa A direct numerical simulation of detonation wave with compressible homogeneous isotropic turbulence is carried out with three different detonation Mach numbers to study the effect of detonation wave

Texas at Arlington, University of

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Detonation Turbulence Interaction L. Massa, M. Chauhan and F. Lu  

E-Print Network [OSTI]

Detonation Turbulence Interaction L. Massa, M. Chauhan and F. Lu This paper reports a numerical study on the effect of turbulence on the detonation wave properties. The analysis is based-mechanics equations in three dimensions to determine the fine-scale evolution. I. Introduction The detonation

Texas at Arlington, University of

442

Center for Turbulence Research Annual Research Briefs 2012  

E-Print Network [OSTI]

and coal fueled combustors. The advantage offered by biomass fuel is that its carbon content has been extracted from the Earth's atmosphere and surface envi- ronment. The combustion of these materials/particle interaction, and turbulence/chemistry interaction. Although turbulence and chemistry interactions are expected

Wang, Wei

443

Turbulence intensity pulse propagation with self-consistent nonlinear noise  

SciTech Connect (OSTI)

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

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

2011-03-15T23:59:59.000Z

444

Turbulence in global simulations of magnetized thin accretion discs  

Science Journals Connector (OSTI)

......profile are also evident in the space-time diagram of the Maxwell stress presented in Davis...question about the nature of MRI-driven MHD turbulence within accretion discs, namely...address the question of whether MRI-driven MHD turbulence within accretion discs is local......

Kris Beckwith; Philip J. Armitage; Jacob B. Simon

2011-09-01T23:59:59.000Z

445

Fluctuations of energy flux in wave turbulence Eric Falcon,1  

E-Print Network [OSTI]

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

Falcon, Eric

446

Basic Properties of Compressible MHD Turbulence: Implications for Molecular Clouds  

E-Print Network [OSTI]

Recent advances in understanding of the basic properties of compressible Magnetohydrodynamic (MHD) turbulence call for revisions of some of the generally accepted concepts. First, MHD turbulence is not so messy as it is usually believed. In fact, the notion of strong non-linear coupling of compressible and incompressible motions is not tenable. Alfven, slow and fast modes of MHD turbulence follow their own cascades and exhibit degrees of anisotropy consistent with theoretical expectations. Second, the fast decay of turbulence is not related to the compressibility of fluid. Rates of decay of compressible and incompressible motions are very similar. Third, viscosity by neutrals does not suppress MHD turbulence in a partially ionized gas. Instead, MHD turbulence develops magnetic cascade at scales below the scale at which neutrals damp ordinary hydrodynamic motions. The implications of those changes of MHD turbulence paradigm for molecular clouds require further studies. Those studies can benefit from testing of theoretical predictions using new statistical techniques that utilize spectroscopic data. We briefly discuss advances in development of tools using which the statistics of turbulent velocity can be recovered from observations.

A. Lazarian; J. Cho

2003-11-17T23:59:59.000Z

447

Tidally Generated Turbulence over the Knight Inlet Sill  

Science Journals Connector (OSTI)

Very high turbulent dissipation rates (above ? = 10?4 W kg?1) were observed in the nonlinear internal lee waves that form each tide over a sill in Knight Inlet, British Columbia. This turbulence was due to both shear instabilities and the ...

Jody M. Klymak; Michael C. Gregg

2004-05-01T23:59:59.000Z

448

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

E-Print Network [OSTI]

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

Fox-Kemper, Baylor

449

Turbulence-Chemistry Interaction in Lean Premixed Hydrogen Combustion  

E-Print Network [OSTI]

Turbulence-Chemistry Interaction in Lean Premixed Hydrogen Combustion A. J. Aspden1,2 , M. S. Day2 between fuel consumption and heat release. Keywords: turbulent premixed combustion, low Mach number flow or hydrogen-rich mixtures obtained from gasi- fication of coal or biomass. These types of fuels provide clean

Bell, John B.

450

Supersonic turbulent boundary layers with periodic mechanical non-equilibrium  

E-Print Network [OSTI]

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

Ekoto, Isaac Wesley

2007-04-25T23:59:59.000Z

451

Lagrangian tetrad dynamics and the phenomenology of turbulence Michael Chertkov  

E-Print Network [OSTI]

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

Chertkov, Mikhael

452

Neutrino oscillations in a turbulent plasma  

SciTech Connect (OSTI)

A new model for the joint neutrino flavor and plasma oscillations is introduced, in terms of the dynamics of the neutrino flavor polarization vector in a plasma background. Fundamental solutions are found for both time-invariant and time-dependent media, considering slow and fast variations of the electron plasma density. The model is shown to be described by a generalized Hamiltonian formalism. In the case of a broad spectrum of electron plasma waves, a statistical approach indicates the shift of both equilibrium value and frequency oscillation of flavor coherence, due to the existence of a turbulent plasma background.

Mendonça, J. T. [Instituto de Física, Universidade de São Paulo, São Paulo, SP, CEP 05508-090 Brazil and IPFN, Instituto Superior Técnico, 1049-001 Lisboa (Portugal)] [Instituto de Física, Universidade de São Paulo, São Paulo, SP, CEP 05508-090 Brazil and IPFN, Instituto Superior Técnico, 1049-001 Lisboa (Portugal); Haas, F. [Departamento de Física, Universidade Federal do Paraná, Curitiba PR, CEP 81531-990 (Brazil)] [Departamento de Física, Universidade Federal do Paraná, Curitiba PR, CEP 81531-990 (Brazil)

2013-07-15T23:59:59.000Z

453

Turbulent flow of gas in fractures  

E-Print Network [OSTI]

. Permeability for Shale core, 20 - 40 mesh sandals . . ~ . . . ~ . ~ . ~ 39 Concentration of proppants vs. Turbulence factor for Shale core, 10 - 20 mesh sands. ~ ~ . , 40 Concentration of proppants vs. Permeability for Shale cox e, 10 - 20 mesh sands... in Figures g and 4. 10 H J K L M A ~e Steel tubings PlaBtlt! tubitlgi mnnumm Alloy A. Core Sample B. Pressure cell C ~ Flowmeter D. High pressure water reservoir E. Heise guage, 10, 000 psi F. Husks pump G. Hydraulic pump, 40, 000 psi H...

Koh, Wong In

2012-06-07T23:59:59.000Z

454

Effects of Magnetic Field on the Turbulent Wake of a Cylinder in MHD Channel Flow  

SciTech Connect (OSTI)

Results from a free-surface MHD flow experiment are presented detailing the modi cation of vortices in the wake of a circular cylinder with its axis parallel to the applied magnetic fi eld. Experiments were performed with a Reynolds number near Re ~ 104 as the interaction parameter, N = |j x#2; B| / |? (? ? ?), was increased through unity. By concurrently sampling the downstream fluid velocity at sixteen cross-stream locations in the wake, it was possible to extract an ensemble of azimuthal velocity profi les as a function of radius for vortices shed by the cylinder at varying strengths of magnetic field. Results indicate a signi cant change in vortex radius and rotation as N is increased. The lack of deviations from the vortex velocity pro file at high magnetic fi elds suggests the absence of small-scale turbulent features. By sampling the wake at three locations downstream in subsequent experiments, the decay of the vortices was examined and the effective viscosity was found to decrease as N-049±0.4. This reduction in effective viscosity is due to the modi cation of the small-scale eddies by the magnetic fi eld. The slope of the energy spectrum was observed to change from a k-1.8 power-law at low N to a k-3.5 power-law for N > 1. Together, these results suggest the flow smoothly transitioned to a quasi-two-dimensional state in the range 0 < N < 1.

John Rhoads, Eric Edlund and Hantao Ji

2013-04-17T23:59:59.000Z

455

Experimental study of elliptical jet from sub to supercritical conditions  

SciTech Connect (OSTI)

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

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

2014-04-15T23:59:59.000Z

456

Visualizing Magneto-Rotational Instability and Turbulent Angular Momentum  

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

Turbulent Angular Momentum Transport Turbulent Angular Momentum Transport Magneto-Rotational Instability and Turbulent Angular Momentum Transport hydroentropyvisit0400.s.x2005.png In space, gases and other matter often form swirling disks around attracting central objects such as newly formed stars. The presence of magnetic fields can cause the disks to become unstable and develop turbulence, causing the disk material to fall onto the central object. This project will carry out large-scale simulations to test theories on how turbulence can develop in such a scenario. These simulations may provide insights into magnetically caused instabilities being studied on a smaller scale in laboratory experiments. In this image volume rendering has been used to visualize the time evolution of hydrodynamic entropy. The color

457

Mass dependency of turbulent parameters in stationary glow discharge plasmas  

SciTech Connect (OSTI)

A direct current glow discharge tube is used to determine how mass changes the effects of certain turbulence characteristics in a weakly ionized gas. Helium, neon, argon, and krypton plasmas were created, and an axial magnetic field, varied from 0.0 to 550.0 Gauss, was used to enhance mass dependent properties of turbulence. From the power spectra of light emission variations associated with velocity fluctuations, determination of mass dependency on turbulent characteristic unstable modes, energy associated with turbulence, and the rate at which energy is transferred from scale to scale are measured. The magnetic field strength is found to be too weak to overcome particle diffusion to the walls to affect the turbulence in all four types of plasmas, though mass dependency is still detected. Though the total energy and the rate at which the energy moves between scales are mass invariant, the amplitude of the instability modes that characterize each plasma are dependent on mass.

Titus, J. B.; Alexander, A. B. [Florida A and M University, Tallahassee, Florida 32310 (United States)] [Florida A and M University, Tallahassee, Florida 32310 (United States); Wiggins, D. L. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53703 (United States)] [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53703 (United States); Johnson, J. A. III [Pyramid Plasmas LLC, Lawrenceville, Georgia 30043 (United States)] [Pyramid Plasmas LLC, Lawrenceville, Georgia 30043 (United States)

2013-05-15T23:59:59.000Z

458

Generalized universal instability: Transient linear amplification and subcritical turbulence  

E-Print Network [OSTI]

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

Landreman, Matt; Dorland, William

2015-01-01T23:59:59.000Z

459

The energetic coupling of scales in gyrokinetic plasma turbulence  

SciTech Connect (OSTI)

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

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

2014-07-15T23:59:59.000Z

460

Enhancement and suppression of heat transfer by MHD turbulence  

E-Print Network [OSTI]

We study of the effect of turbulence on heat transfer within magnetized plasmas for energy injection velocities both larger and smaller that the Alfven speed. We find that in the latter regime the heat transfer is partially suppressed, while in the former regime the effects of turbulence depend on the intensity of driving. In fact, the scale l at which the turbulent velocity is equal the Alfven velocity is a new important parameter. When the electron mean free path is larger than l, the stronger the the turbulence, the lower thermal conductivity by electrons is. The turbulent motions, however, induces their own advective heat transport, which, for the parameters of intracluster medium (ICM) provides effective heat diffusivity that exceeds the classical Spitzer value.

A. Lazarian

2006-08-02T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Reconnection events in two-dimensional Hall magnetohydrodynamic turbulence  

SciTech Connect (OSTI)

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

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

2012-09-15T23:59:59.000Z

462

Statistical models for spatial patterns of inertial particles in turbulence  

E-Print Network [OSTI]

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

Gustavsson, K

2014-01-01T23:59:59.000Z

463

Jet momentum balance independent of shear viscosity  

E-Print Network [OSTI]

Jet momentum balance measurements, such as those recently performed by the CMS collaboration, provide an opportunity to quantify the energy transferred from a parton shower to the underlying medium in heavy-ion collisions. Specifically, I argue that the Cooper-Frye freezeout distribution associated with the energy and momentum deposited by the parton shower is controlled to a significant extent by the distribution of the underlying bulk matter and independent of the details of how deposited energy is redistributed in the medium, which is largely determined by transport coefficients such as shear viscosity. Thus by matching the distribution of momentum associated with the secondary jet in such measurements to the thermal distribution of the underlying medium, one can obtain a model independent estimate on the amount of parton shower energy deposited.

R. B. Neufeld

2011-08-31T23:59:59.000Z

464

Cryogenic target formation using cold gas jets  

DOE Patents [OSTI]

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

Hendricks, Charles D. (Livermore, CA)

1981-01-01T23:59:59.000Z

465

Phenomenology of Gamma-Ray Jets  

E-Print Network [OSTI]

We discuss some phenomenological aspects of $\\gamma$-ray emitting jets. In particular, we present calculations of the $\\gamma$-sphere and $\\pi$-sphere for various target photon fields, and employ them to demonstrate how $\\gamma$-ray observations at very high energies can be used to constraint the Doppler factor of the emitting plasma and the production of VHE neutrinos. We also consider the implications of the rapid TeV variability observed in M87 and the TeV blazars, and propose a model for the very rapid TeV flares observed with HESS and MAGIC in some blazars,that accommodates the relatively small Doppler factors inferred from radio observations. Finally, we briefly discuss the prospects for detecting VHE neutrinos from relativistic jets.

Amir Levinson

2007-09-10T23:59:59.000Z

466

Cross hedging jet-fuel price exposure  

Science Journals Connector (OSTI)

This paper investigates the cross hedging performance of several oil forwards contracts using WTI, Brent, gasoil and heating oil to manage jet-fuel spot price exposure. We apply three econometric techniques that have been widely tested and applied in the cross hedging literature on foreign exchange and stock index futures markets. Using quotes from the financial industry on forward contracts, we can show that the optimal cross hedging instrument depends on the maturity of the instrument's forwards contract. The results highlight that the standard approach in the literature to use crude oil as a cross hedge is not optimal for time horizons of three months or less. By contrast, for short hedging horizons our results indicate that gasoil forwards contracts represent the highest cross hedging efficiency for jet-fuel spot price exposure, while for maturities of more than three months, the predominance of gasoil diminishes in comparison to WTI and Brent.

Zeno Adams; Mathias Gerner

2012-01-01T23:59:59.000Z

467

Dense, vertical jet in stagnant homogeneous fluid  

E-Print Network [OSTI]

30. 4 53. 2 76. 0 21. 5 37. 6 53. 7 17. 5 30. 7 41. 6 3. 1 5. 4 7. 7 G. l 10. 0 15. 4 9. 2 16. 1 21. 9 0. 16 0. 28 0. 40 0. 65 1. 13 l. 62 1. 46 2. 55 3 45 H/D 50. 0 50. 0 50. 0 25. 0 25. 0 25. 0 16. 7 16, 7 16. 7...) m D 120 80 1 m D d Jet Height(from the nozzle) Abraham Jet or nozzle diameter (slope = 1. 94) Riser height H/d 0 5 r liater depth(Tank depth) (slope 1 89) L4 ft. (1. 22 m. )] s 0 pe' H/d = 0. 333 I +Turner (slope = 1. 82) ~~ ~ (slope...

Vergara, Ignacio

2012-06-07T23:59:59.000Z

468

Azimuthal Jet Tomography at RHIC and LHC  

E-Print Network [OSTI]

A generic jet-energy loss model that is coupled to state-of-the-art hydrodynamic fields and interpolates between a wide class of running coupling pQCD-based and AdS/CFT-inspired models is compared to recent data on the azimuthal and transverse momentum dependence of high-pT pion nuclear modification factors and high-pT elliptic flow measured at RHIC and LHC. We find that RHIC data are surprisingly consistent with various scenarios considered. However, extrapolations to LHC energies favor running coupling pQCD-based models of jet-energy loss. While conformal holographic models are shown to be inconsistent with data, recent non-conformal generalizations of AdS holography may provide an alternative description.

Barbara Betz; Miklos Gyulassy

2014-02-14T23:59:59.000Z

469

Cryogenic target formation using cold gas jets  

DOE Patents [OSTI]

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets are disclosed. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member. 4 figs.

Hendricks, C.D.

1980-02-26T23:59:59.000Z

470

Cryogenic target formation using cold gas jets  

DOE Patents [OSTI]

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

Hendricks, Charles D. [Livermore, CA

1980-02-26T23:59:59.000Z

471

Thomson scattering measurements in atmospheric plasma jets  

Science Journals Connector (OSTI)

Electron temperature and electron density in a dc plasma jet at atmospheric pressure have been obtained using Thomson laser scattering. Measurements performed at various scattering angles have revealed effects that are not accounted for by the standard scattering theory. Differences between the predicted and experimental results suggest that higher order corrections to the theory may be required, and that corrections to the form of the spectral density function may play an important role.

G. Gregori; J. Schein; P. Schwendinger; U. Kortshagen; J. Heberlein; E. Pfender

1999-02-01T23:59:59.000Z

472

NLO QCD Predictions for W+3 jets  

SciTech Connect (OSTI)

In this contribution we present results from the NLO computation of the production of a W boson in association with three jets in hadronic collisions. The results are obtained by combining two programs: BlackHat for the virtual one-loop matrix elements and Sherpa for the real-emission contributions. We present results for the Tevatron and the LHC, and address the issue of the choice of a common factorization and renormalization scale for this process.

Maitre, Daniel; /Durham U.; Berger, Carola F.; /MIT; Bern, Zvi; Febres Cordero, Fernando; Ita, Harald; Dixon, Lance J.; Forde, Darren; Gleisberg, Tanju; /UCLA /SLAC; Kosower, David; /Saclay, SPhT

2009-12-09T23:59:59.000Z

473

Particle transport in turbulent curved pipe flow  

E-Print Network [OSTI]

Direct numerical simulations (DNS) of particle-laden turbulent flow in straight, mildly curved and strongly bent pipes are performed in which the solid phase is modelled as small heavy spherical particles. The objective is to examine the effect of the curvature on particle transport and accumulation, in particular how the turbophoretic drift of the particles is affected by weak and strong secondary motions of the carrier phase and geometry-induced centrifugal forces. A total of seven populations of dilute particles with different Stokes numbers, one-way coupled with their carrier phase, are simulated. Even a slight non-zero curvature in the flow configuration shows a strong impact on the particle dynamics. Near-wall helicoidal particle streaks are observed in the curved configurations with their inclination varying with the strength of the secondary motion of the carrier phase. A reflection layer, as previously observed in particle laden turbulent S-shaped channels, is also apparent in the strongly curved pip...

Noorani, Azad; Brandt, Luca; Schlatter, Philipp

2015-01-01T23:59:59.000Z

474

Flame front geometry in premixed turbulent flames  

SciTech Connect (OSTI)

Experimental and numerical determinations of flame front curvature and orientation in premixed turbulent flames are presented. The experimental data is obtained from planar, cross sectional images of stagnation point flames at high Damkoehler number. A direct numerical simulation of a constant energy flow is combined with a zero-thickness, constant density flame model to provide the numerical results. The computational domain is a 32{sup 3} cube with periodic boundary conditions. The two-dimensional curvature distributions of the experiments and numerical simulations compare well at similar q{prime}/S{sub L} values with means close to zero and marked negative skewness. At higher turbulence levels the simulations show that the distributions become symmetric about zero. These features are also found in the three dimensional distributions of curvature. The simulations support assumptions which make it possible to determine the mean direction cosines from the experimental data. This leads to a reduction of 12% in the estimated flame surface area density in the middle of the flame brush. 18 refs.

Shepherd, I.G. (Lawrence Berkeley Lab., CA (United States)); Ashurst, W.T. (Sandia National Labs., Livermore, CA (United States))

1991-12-01T23:59:59.000Z

475

On detecting oscillations of gamma rays into axion-like particles in turbulent and coherent magnetic fields  

E-Print Network [OSTI]

Background radiation fields pervade the Universe, and above a certain energy any $\\gamma$-ray flux emitted by an extragalactic source should be attenuated due to $e^+e^-$ pair production. The opacity could be alleviated if photons oscillated into hypothetical axion-like particles (ALPs) in ambient magnetic fields, leading to a $\\gamma$-ray excess especially at high optical depths that could be detected with imaging air Cherenkov telescopes (IACTs). Here, we introduce a method to search for such a signal in $\\gamma$-ray data and to estimate sensitivities for future observations. Different magnetic fields close to the $\\gamma$-ray source are taken into account in which photons can convert into ALPs that then propagate unimpeded over cosmological distances until they re-convert in the magnetic field of the Milky Way. Specifically, we consider the coherent field at parsec scales in a blazar jet as well as the turbulent field inside a galaxy cluster. For the latter, we explicitly derive the transversal components of a magnetic field with gaussian turbulence which are responsible for the photon-ALP mixing. To illustrate the method, we apply it to a mock IACT array with characteristics similar to the Cherenkov Telescope Array and investigate the dependence of the sensitivity to detect a $\\gamma$-ray excess on the magnetic-field parameters.

Manuel Meyer; Daniele Montanino; Jan Conrad

2014-09-04T23:59:59.000Z

476

Sting jets in intense winter North-Atlantic windstorms  

Science Journals Connector (OSTI)

Extratropical cyclones dominate autumn and winter weather over western Europe. The strongest cyclones, often termed windstorms, have a large socio-economic impact due to the strong surface winds and associated storm surges in coastal areas. Here we show that sting jets are a common feature of windstorms; up to a third of the 100 most intense North-Atlantic winter windstorms over the last two decades satisfy conditions for sting jets. The sting jet is a mesoscale descending airstream that can cause strong near-surface winds in the dry slot of the cyclone, a region not usually associated with strong winds. Despite their localized transient nature, these sting jets can cause significant damage, a prominent example being the storm that devastated southeast England on 16 October 1987. We present the first regional climatology of windstorms with sting jets. Previously analysed sting-jet cases appear to have been exceptional in their track over northwest Europe rather than in their strength.

Oscar Martínez-Alvarado; Suzanne L Gray; Jennifer L Catto; Peter A Clark

2012-01-01T23:59:59.000Z

477

Polarization and energy content of parsec scale AGN jets  

E-Print Network [OSTI]

Most of energy carried by relativistic AGN jets remains undetected until hundreds of kiloparsecs where interaction with intergalactic medium produces hot spots. The jet's hidden energy is only partially dissipated at smaller scales, from parsecs to kiloparsecs. Several media may play the role of the ``prime mover'': ions, pairs or large scale magnetic fields. Analyzing VLBI polarization structures of relativistic parsec scale jets we conclude that large-scale magnetic fields can explain the salient polarization properties of parsec-scale AGN jets. This implies that large-scale magnetic fields carry a non-negligible fraction of jet luminosity. We also discuss the possibility that relativistic AGN jets may be electromagnetically (Poynting flux) dominated. In this case, dissipation of the toroidal magnetic field (and not fluid shocks) may be responsible for particle acceleration.

Maxim Lyutikov; Vladimir I. Pariev; Denise C. Gabuzda

2004-11-15T23:59:59.000Z

478

Jet conversions in a quark-gluon plasma  

Science Journals Connector (OSTI)

Quark and gluon jets traversing through a quark-gluon plasma not only lose their energies but also can undergo flavor conversions. The conversion rates via the elastic q(q¯)g?gq(q¯) and the inelastic qq¯?gg scatterings are evaluated in the lowest order in QCD. Including both jet energy loss and conversions in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we have found a net of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/?+ and p¯/?- ratios at high transverse momentum. However, a much larger net quark-to-gluon jet conversion rate than the one given by the lowest order QCD is needed to account for the observed similar ratios in central Au+Au and p+p collisions at the same energy. Implications of our results are discussed.

W. Liu; C. M. Ko; B. W. Zhang

2007-05-04T23:59:59.000Z

479

Studies of Relativistic Jets in Active Galactic Nuclei with SKA  

E-Print Network [OSTI]

Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. These questions will be addressed specially through analysis of the massive data sets arising from the deep, all-sky surveys (both total and polarimetric flux) from SKA1. Wide-field very-long-baseline-interferometric survey observations involving SKA1 will serve as a unique tool for distinguishing between extragalactic relativistic jets and star forming galaxies via brightness temperature measurements. Subsequent SKA1 studies of relativistic jets at different resolutions will allow for unprecedented cosmological studies of AGN jets up...

Agudo, Ivan; Falcke, Heino; Georganopoulos, Markos; Ghisellini, Gabriele; Giovannini, Gabriele; Giroletti, Marcello; Gomez, Jose L; Gurvits, Leonid; Laing, Robert; Lister, Matthew; Marti, Jose-Maria; Meyer, Eileen T; Mizuno, Yosuke; O'Sullivan, Shane; Padovani, Paolo; Paragi, Zsolt; Perucho, Manel; Schleicher, Dominik; Stawarz, Lukasz; Vlahakis, Nektarios; Wardle, John

2015-01-01T23:59:59.000Z

480

Laser photons acquire circular polarization by interacting with a Dirac or Majorana neutrino beam  

E-Print Network [OSTI]

It is shown that for the reason of neutrinos being left-handed and their gauge-couplings being parity-violated, linearly polarized photons acquire their circular polarization by interacting with neutrinos. Calculating the ratio of linear and circular polarizations of laser photons interacting with either Dirac or Majorana neutrino beam, we obtain this ratio for the Dirac neutrino case, which is about twice less than the ratio for the Majorana neutrino case. Based on this ratio, we discuss the possibility of using advanced laser facilities and the T2K neutrino experiment to measure the circular polarization of laser beams interacting with neutrino beams in ground laboratories. This could be an additional and useful way to gain some insight into the physics of neutrinos, for instance their Dirac or Majorana nature.

Rohoollah Mohammadi; She-Sheng Xue

2014-03-14T23:59:59.000Z

Note: This page contains sample records for the topic "turbulent circular jet" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

MEASURING THE JET POWER OF FLAT-SPECTRUM RADIO QUASARS  

SciTech Connect (OSTI)

We use frequency-dependent position shifts of flat-spectrum radio cores to estimate the kinetic power of active galactic nucleus (AGN) jets. We find a correlation between the derived jet powers and AGN narrow-line luminosity, consistent with the well-known relation for radio galaxies and steep spectrum quasars. This technique can be applied to intrinsically weak jets even at high redshift.

Shabala, S. S.; Santoso, J. S. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, TAS 7001 (Australia); Godfrey, L. E. H. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

2012-09-10T23:59:59.000Z

482

A PRECESSING JET IN THE CH Cyg SYMBIOTIC SYSTEM  

SciTech Connect (OSTI)

Jets have been detected in only a few symbiotic binaries to date, and CH Cyg is one of them. In 2001, a non-relativistic jet was detected in CH Cyg for the first time in X-rays. We carried out coordinated Chandra, Hubble Space Telescope (HST), and VLA observations in 2008 to study the propagation of this jet and its interaction with the circumbinary medium. We detected the jet with Chandra and HST and determined that the apex has expanded to the south from {approx}300 AU to {approx}1400 AU, with the shock front propagating with velocity <100 km s{sup -1}. The shock front has significantly slowed down since 2001. Unexpectedly, we also discovered a powerful jet in the NE-SW direction, in the X-ray, optical and radio. This jet has a multi-component structure, including an inner jet and a counterjet at {approx}170 AU, and a SW component ending in several clumps extending out to {approx}750 AU. The structure of the jet and the curvature of the outer portion of the SW jet suggest an episodically powered precessing jet or a continuous precessing jet with occasional mass ejections or pulses. We carried out detailed spatial mapping of the X-ray emission and correlation with the optical and radio emission. X-ray spectra were extracted from the central source, inner NE counterjet, and the brightest clump at a distance of {approx}500 AU from the central source. We discuss the initial results of our analyses, including the multi-component spectral fitting of the jet components and of the central source.

Karovska, Margarita; Gaetz, Terrance J.; Raymond, John C.; Lee, Nicholas P. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Carilli, Christopher L. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Hack, Warren [Space Telescope Science Institute, Baltimore, MD 21218-2463 (United States)], E-mail: mkarovska@cfa.harvard.edu

2010-02-20T23:59:59.000Z

483

Study of Emission TurbulenceRadiation Interaction in Hypersonic Boundary Layers  

E-Print Network [OSTI]

Study of Emission Turbulence­Radiation Interaction in Hypersonic Boundary Layers L. Duan and M. P of emission turbulence­radiation interaction in hypersonic turbulent boundary layers, representative interaction between turbulence and emission at the hypersonic environment under investigation. An explanation

Martín, Pino

484

On Measuring the Terms of the Turbulent Kinetic Energy Budget from an AUV LOUIS GOODMAN  

E-Print Network [OSTI]

of production of turbulent kinetic energy (TKE). Heat flux is obtained by correlating the vertical velocityOn Measuring the Terms of the Turbulent Kinetic Energy Budget from an AUV LOUIS GOODMAN School of the steady-state, homogeneous turbulent kinetic energy budgets are obtained from mea- surements of turbulence

Goodman, Louis

485

Interaction of Nocturnal Low-Level Jets with Urban Geometries as seen in Joint URBAN 2003 Data  

SciTech Connect (OSTI)

As accurate modeling of atmospheric flows in urban environments requires sophisticated representation of complex urban geometries, much work has been devoted to treatment of the urban surface. However, the importance of the larger-scale flow impinging upon the urban complex to the flow, transport and dispersion within it and downwind has received less attention. Building-resolving computational fluid dynamics (CFD) models are commonly employed to investigate interactions between the flow and three-dimensional structures comprising the urban environment, however such models are typically forced with simplified boundary conditions that fail to include important regional-scale phenomena that can strongly influence the flow within the urban complex and downwind. This paper investigates the interaction of an important and frequently occurring regional-scale phenomenon, the nocturnal low-level jet (LLJ), with urban-scale turbulence and dispersion in Oklahoma City using data from the Joint URBAN 2003 (JU2003) field experiment. Two simulations of nocturnal tracer release experiments from JU2003 using Lawrence Livermore National laboratory's FEM3MP CFD model yield differing levels of agreement with the observations in wind speed, turbulence kinetic energy (TKE) and concentration profiles in the urban wake, approximately 750m downwind of the central business district. Profiles of several observed turbulence parameters at this location indicate characteristics of both bottom-up and top-down boundary layers during each of the experiments. These data are consistent with turbulence production due to at least two sources, the complex flow structures of the urban area and the region of strong vertical wind shear occurring beneath the LLJs present each night. While strong LLJs occurred each night, their structures varied considerably, resulting in significant differences in the magnitudes of the turbulence parameters observed during the two experiments. As FEM3MP was forced only with an upwind velocity profile that did not adequately represent the LLJ, the downward propagation of TKE observed during the experiments was absent from the simulations. As such, the differing levels of agreement between the simulations and observations during the two experiments can, in part, be explained by their exclusion of this important larger-scale influence. We demonstrate the ability of the Weather Research and Forecast Model (WRF) to simulate accurate velocity fields during each night, and identify the use of regional-scale s