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Note: This page contains sample records for the topic "turbulence velocity wave" 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

Spectral Wave–Turbulence Decomposition  

Science Conference Proceedings (OSTI)

A new method of wave–turbulence decomposition is introduced, for which the only instrument required is one high-frequency pointwise velocity sensor. This is a spectral method that assumes equilibrium turbulence and no wave–turbulence interaction. ...

Jeremy D. Bricker; Stephen G. Monismith

2007-08-01T23:59:59.000Z

2

Effects of Wave Breaking on the Near-Surface Profiles of Velocity and Turbulent Kinetic Energy  

Science Conference Proceedings (OSTI)

A theoretical model for the near-surface velocity profile in the presence of breaking waves is presented. Momentum is accumulated by growing waves and is released upon wave breaking. In effect, such a transition is a process involving a time-...

Arne Melsom; Řyvind SĆtra

2004-02-01T23:59:59.000Z

3

Strong Turbulence in the Wave Crest Region  

Science Conference Proceedings (OSTI)

High-resolution vertical velocity profiles in the surface layer of a lake reveal the turbulence structure beneath strongly forced waves. Dissipation rates of turbulence kinetic energy are estimated based on centered second-order structure ...

Johannes Gemmrich

2010-03-01T23:59:59.000Z

4

The Direct Estimation of Near-Bottom Turbulent Fluxes in the Presence of Energetic Wave Motions  

Science Conference Proceedings (OSTI)

Velocities produced by energetic waves can contaminate direct covariance estimates of near-bottom turbulent shear stress and turbulent heat flux. A new adaptive filtering technique is introduced to minimize the contribution of wave-induced ...

W. J. Shaw; J. H. Trowbridge

2001-09-01T23:59:59.000Z

5

On the theory of turbulent flame velocity  

E-Print Network (OSTI)

The renormalization ideas of self-similar dynamics of a strongly turbulent flame front are applied to the case of a flame with realistically large thermal expansion of the burning matter. In that case a flame front is corrugated both by external turbulence and the intrinsic flame instability. The analytical formulas for the velocity of flame propagation are obtained. It is demonstrated that the flame instability is of principal importance when the integral turbulent length scale is much larger than the cut off wavelength of the instability. The developed theory is used to analyse recent experiments on turbulent flames propagating in tubes. It is demonstrated that most of the flame velocity increase measured experimentally is provided by the large scale effects like the flame instability, and not by the small-scale external turbulence.

Vitaly Bychkov; Vyacheslav Akkerman; Arkady Petchenko

2012-10-19T23:59:59.000Z

6

Fossil turbulence and fossil turbulence waves can be dangerous  

E-Print Network (OSTI)

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

Carl H Gibson

2012-11-25T23:59:59.000Z

7

Wave–Turbulence Interactions in a Breaking Mountain Wave  

Science Conference Proceedings (OSTI)

The mean and turbulent structures in a breaking mountain wave are considered through an ensemble of high-resolution (essentially large-eddy simulation) wave-breaking calculations. Of particular interest are the turbulent heat and momentum fluxes ...

Craig C. Epifanio; Tingting Qian

2008-10-01T23:59:59.000Z

8

Kinematics of Turbulence Convected by a Random Wave Field  

Science Conference Proceedings (OSTI)

Turbulent velocity spectra measured beneath wind waves show a large enhancement about the central wave frequency. A “5/3" frequency dependence can be seen both above and below the central peak, but with an apparent increase in spectral density at ...

J. L. Lumley; E. A. Terray

1983-11-01T23:59:59.000Z

9

Velocity-Space Proton Diffusion in the Solar Wind Turbulence  

E-Print Network (OSTI)

We study a velocity-space quasilinear diffusion of the solar wind protons driven by oblique Alfven turbulence at proton kinetic scales. Turbulent fluctuations at these scales possess properties of kinetic Alfven waves (KAWs) that are efficient in Cherenkov resonant interactions. The proton diffusion proceeds via Cherenkov kicks and forms a quasilinear plateau - nonthermal proton tail in the velocity distribution function (VDF). The tails extend in velocity space along the mean magnetic field from 1 to (1.5-3) VA, depending on the spectral break position, turbulence amplitude at the spectral break, and spectral slope after the break. The most favorable conditions for the tail generation occur in the regions where the proton thermal and Alfven velocities are about the same, VTp/VA = 1. The estimated formation times are within 1-2 h for typical tails at 1 AU, which is much shorter than the solar wind expansion time. Our results suggest that the nonthermal proton tails, observed in-situ at all heliocentric distan...

Voitenko, Yuriy

2013-01-01T23:59:59.000Z

10

Kinetic Energy Transfer between Internal Gravity Waves and Turbulence  

Science Conference Proceedings (OSTI)

We describe a reliable method for distinguishing the mean, wave and turbulence fields when internal waves with changing amplitude perturb the turbulent boundary layer. By integrating the component wave and turbulence kinetic energy budgets ...

J. J. Finnigan

1988-02-01T23:59:59.000Z

11

An Analysis of Wave-Turbulence Interaction  

Science Conference Proceedings (OSTI)

We present the results of an analytical and numerical calculation of the interaction between an internal gravity wave and a wave-induced turbulence. The initial atmospheric state, assumed horizontally homogeneous, is statically and dynamically ...

D. Fua; G. Chimonas; F. Einaudi; O. Zeman

1982-11-01T23:59:59.000Z

12

Generation of Turbulence by Atmospheric Gravity Waves  

Science Conference Proceedings (OSTI)

The standard current criterion for the generation of turbulence by atmospheric gravity waves and for the associated limitation on wave growth is based upon the standard criterion for static instability of the unperturbed atmosphere, namely, that ...

Colin O. Hines

1988-04-01T23:59:59.000Z

13

Near-Surface Turbulence in the Presence of Breaking Waves  

Science Conference Proceedings (OSTI)

Observations with a three-axis pulse-to-pulse coherent acoustic Doppler profiler and acoustic resonators reveal the turbulence and bubble field beneath breaking waves in the open ocean at wind speeds up to 14 m s?1. About 55%–80% of velocity ...

Johannes R. Gemmrich; David M. Farmer

2004-05-01T23:59:59.000Z

14

Simulation of Three-Dimensional Turbulent Velocity Fields  

Science Conference Proceedings (OSTI)

New algorithms for the simulation of three-dimensional homogeneous turbulent velocity fields are compared with standard spectral domain algorithms. Results are presented for a von Kármán model of the covariance tensor. For typical atmospheric ...

Rod Frehlich; Larry Cornman; Robert Sharman

2001-02-01T23:59:59.000Z

15

Multiple mapping conditioning of velocity in turbulent jet flames  

Science Conference Proceedings (OSTI)

Multiple mapping conditioning (MMC) has emerged as a new approach to model turbulent reacting flows. This study revises the standard MMC closure for velocity in turbulent jet flows from linearity in the reference space to linearity in the composition space. This modeling amendment ensures that the standard velocity model in conditional moment closure studies can now be used for MMC computation as well. A simplified model for the velocity-dependence of MMC drift coefficients is derived without loss of generality and is implemented for the revised velocity closure. Modeling results have been corroborated against the Direct Numerical Simulation database of a spatially evolving, planar turbulent jet flame. The revised model shows marked improvement over standard MMC closure in predicting velocity statistics close to the nozzle. (author)

Vaishnavi, P. [Mechanical Engineering Department, Imperial College, London SW7 2AZ (United Kingdom); Kronenburg, A. [Institut fuer Technische Verbrennung, Universitaet Stuttgart, 70174 Stuttgart (Germany)

2010-10-15T23:59:59.000Z

16

Atmospheric Gravity Waves and Aircraft Turbulence Encounters  

Science Conference Proceedings (OSTI)

We describe aircraft turbulence-atmospheric gravity wave events which occurred during a 2-day period over the Continental Divide. The waves are observed by two microbarograph networks an each side of the divide and last for several hours at a ...

A. J. Bedard Jr.; F. Canavero; F. Einaudi

1986-12-01T23:59:59.000Z

17

Edge Turbulence Velocity Changes with Lithium Coating on NSTX  

SciTech Connect

Lithium coating improves energy confinement and eliminates edge localized modes in NSTX, but the mechanism of this improvement is not yet well understood. We used the gas-puff-imaging (GPI) diagnostic on NSTX to measure the changes in edge turbulence which occurred during a scan with variable lithium wall coating, in order to help understand the reason for the confinement improvement with lithium. There was a small increase in the edge turbulence poloidal velocity and a decrease in the poloidal velocity fluctuation level with increased lithium. The possible effect of varying edge neutral density on turbulence damping was evaluated for these cases in NSTX. __________________________________________________

A. Cao, S.J. Zweben, D.P. Stotler, M. Bell, A. Diallo, S.M. Kaye and B. LeBlanc

2012-08-10T23:59:59.000Z

18

Plasma transport induced by kinetic Alfven wave turbulence  

SciTech Connect

At the Earth's magnetopause that separates the hot-tenuous magnetospheric plasma from the cold dense solar wind plasma, often seen is a boundary layer where plasmas of both origins coexist. Plasma diffusions of various forms have been considered as the cause of this plasma mixing. Here, we investigate the plasma transport induced by wave-particle interaction in kinetic Alfven wave (KAW) turbulence, which is one of the candidate processes. We clarify that the physical origin of the KAW-induced cross-field diffusion is the drift motions of those particles that are in Cerenkov resonance with the wave: E Multiplication-Sign B-like drift that emerges in the presence of non-zero parallel electric field component and grad-B drift due to compressional magnetic fluctuations. We find that KAW turbulence, which has a spectral breakpoint at which an MHD inertial range transits to a dissipation range, causes selective transport for particles whose parallel velocities are specified by the local Alfven velocity and the parallel phase velocity at the spectral breakpoint. This finding leads us to propose a new data analysis method for identifying whether or not a mixed plasma in the boundary layer is a consequence of KAW-induced transport across the magnetopause. The method refers to the velocity space distribution function data obtained by a spacecraft that performs in situ observations and, in principle, is applicable to currently available dataset such as that provided by the NASA's THEMIS mission.

Izutsu, T. [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Hasegawa, H.; Fujimoto, M. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Nakamura, T. K. M. [X-Computational Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2012-10-15T23:59:59.000Z

19

Measurement of turbulent wind velocities using a rotating boom apparatus  

DOE Green Energy (OSTI)

The present report covers both the development of a rotating-boom facility and the evaluation of the spectral energy of the turbulence measured relative to the rotating boom. The rotating boom is composed of a helicopter blade driven through a pulley speed reducer by a variable speed motor. The boom is mounted on a semiportable tower that can be raised to provide various ratios of hub height to rotor diameter. The boom can be mounted to rotate in either the vertical or horizontal plane. Probes that measure the three components of turbulence can be mounted at any location along the radius of the boom. Special hot-film sensors measured two components of the turbulence at a point directly in front of the rotating blade. By using the probe rotated 90/sup 0/ about its axis, the third turbulent velocity component was measured. Evaluation of the spectral energy distributions for the three components of velocity indicates a large concentration of energy at the rotational frequency. At frequencies slightly below the rotational frequency, the spectral energy is greatly reduced over that measured for the nonrotating case measurements. Peaks in the energy at frequencies that are multiples of the rotation frequency were also observed. We conclude that the rotating boom apparatus is suitable and ready to be used in experiments for developing and testing sensors for rotational measurement of wind velocity from wind turbine rotors. It also can be used to accurately measure turbulent wind for testing theories of rotationally sampled wind velocity.

Sandborn, V.A.; Connell, J.R.

1984-04-01T23:59:59.000Z

20

Modification of Proton Velocity Distributions by Alfvenic Turbulence in the Solar Wind  

E-Print Network (OSTI)

In the present paper, the proton velocity distribution function (VDF)in the solar wind is determined by solving numerically the kinetic evolution equation. We compare the results obtained when considering the effects of ex- ternal forces and Coulomb collisions with those obtained by adding effects of Alfven wave turbulence. We use Fokker-Planck diffusion terms due to Alfvenic turbulence, which take into account observed turbulence spectra and kinetic effects of finite proton gyroradius. Assuming a displaced Maxwellian for the proton VDF at the simulation boundary at 14 solar radii, we show that the turbulence leads to a fast (within several solar radii) development of the anti-sunward tail in the proton VDF. Our results provide a natural explanation for the nonthermal tails in the proton VDFs, which are often observed in-situ in the solar wind beyond 0.3 AU.

Pierrard, Viviane

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Renormalized Resonance Quartets in Dispersive Wave Turbulence  

Science Conference Proceedings (OSTI)

Using the (1+1)D Majda-McLaughlin-Tabak model as an example, we present an extension of the wave turbulence (WT) theory to systems with strong nonlinearities. We demonstrate that nonlinear wave interactions renormalize the dynamics, leading to (i) a possible destruction of scaling structures in the bare wave systems and a drastic deformation of the resonant manifold even at weak nonlinearities, and (ii) creation of nonlinear resonance quartets in wave systems for which there would be no resonances as predicted by the linear dispersion relation. Finally, we derive an effective WT kinetic equation and show that our prediction of the renormalized Rayleigh-Jeans distribution is in excellent agreement with the simulation of the full wave system in equilibrium.

Lee, Wonjung [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Kovacic, Gregor [Mathematical Sciences Department, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Cai, David [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Mathematics Department, Shanghai Jiao Tong University, Shanghai 200240 (China)

2009-07-10T23:59:59.000Z

22

Statistical Parameters of the Air Turbulent Boundary Layer over Steep Water Waves Measured by the PIV Technique  

Science Conference Proceedings (OSTI)

A turbulent airflow with a centerline velocity of 4 m s?1 above 2.5-Hz mechanically generated gravity waves of different amplitudes has been studied in experiments using the particle image velocimetry (PIV) technique. Direct measurements of the ...

Yu. Troitskaya; D. Sergeev; O. Ermakova; G. Balandina

2011-08-01T23:59:59.000Z

23

Turbulence Closure, Steady State, and Collapse into Waves  

Science Conference Proceedings (OSTI)

A new simple two-equation turbulence closure is constructed by hypothesizing that there is an extra energy sink in the turbulent kinetic energy (k) equation representing the transfer of energy from k to internal waves and other nonturbulent ...

Helmut Baumert; Hartmut Peters

2004-02-01T23:59:59.000Z

24

Comments on “Turbulence Closure, Steady State, and Collapse into Waves  

Science Conference Proceedings (OSTI)

Two-equation models are being increasingly used to model turbulence in geophysical flows. A salient aspect of these flows is the stable gravitational stratification, which implies that turbulent fluctuations can generate internal waves that drain ...

Lakshmi H. Kantha

2005-01-01T23:59:59.000Z

25

Co-existence of whistler waves with kinetic Alfven wave turbulence for the high-beta solar wind plasma  

SciTech Connect

It is shown that the dispersion relation for whistler waves is identical for a high or low beta plasma. Furthermore, in the high-beta solar wind plasma, whistler waves meet the Landau resonance with electrons for velocities less than the thermal speed, and consequently, the electric force is small compared to the mirror force. As whistlers propagate through the inhomogeneous solar wind, the perpendicular wave number increases through refraction, increasing the Landau damping rate. However, the whistlers can survive because the background kinetic Alfven wave (KAW) turbulence creates a plateau by quasilinear (QL) diffusion in the solar wind electron distribution at small velocities. It is found that for whistler energy density of only {approx}10{sup -3} that of the kinetic Alfven waves, the quasilinear diffusion rate due to whistlers is comparable to KAW. Thus, very small amplitude whistler turbulence can have a significant consequence on the evolution of the solar wind electron distribution function.

Mithaiwala, Manish; Crabtree, Chris; Ganguli, Gurudas [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5346 (United States); Rudakov, Leonid [Icarus Research Inc., P.O. Box 30780, Bethesda, Maryland 20824-0780 (United States)

2012-10-15T23:59:59.000Z

26

Compressible Turbulence and Interactions with Shock Waves and Material  

NLE Websites -- All DOE Office Websites (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

27

High Frequency Acoustic Wave Scattering From Turbulent Premixed Flames .  

E-Print Network (OSTI)

??This thesis describes an experimental investigation of high frequency acoustic wave scattering from turbulent premixed flames. The objective of this work was to characterize the… (more)

Narra, Venkateswarlu

2008-01-01T23:59:59.000Z

28

Analysis of the Wave Scattering From Turbulent Premixed Flame .  

E-Print Network (OSTI)

??A theoretical investigation of acoustic wave interactions with turbulent premixed flames was performed. Such interactions affect the characteristic unsteadiness of combustion processes, e.g., combustion instabilities.… (more)

Cho, Ju Hyeong

2006-01-01T23:59:59.000Z

29

Internal Wave–Wave Interactions. Part II: Spectral Energy Transfer and Turbulence Production  

Science Conference Proceedings (OSTI)

The spectral transfer of internal wave energy toward high vertical wavenumber kz and turbulence production ? is examined by ray tracing small-scale test waves in a canonical Garrett and Munk background wave field. Unlike previous ray-tracing ...

Haili Sun; Eric Kunze

1999-11-01T23:59:59.000Z

30

Longshore sediment transport rate calculated incorporating wave orbital velocity fluctuations  

E-Print Network (OSTI)

Laboratory experiments were performed to study and improve longshore sediment transport rate predictions. Measured total longshore transport in the laboratory was approximately three times greater for plunging breakers than spilling breakers. Three distinct zones of longshore transport were observed across the surf zone: the incipient breaker zone, inner surf zone, and swash zone. Transport at incipient breaking was influenced by breaker type; inner surf zone transport was dominated by wave height, independent of wave period; and swash zone transport was dependent on wave period. Selected predictive formulas to compute total load and distributed load transport were compared to laboratory and field data. Equations by Kamphuis (1991) and Madsen et al. (2003) gave consistent total sediment transport estimates for both laboratory and field data. Additionally, the CERC formula predicted measurements well if calibrated and applied to similar breaker types. Each of the distributed load models had shortcomings. The energetics model of Bodge and Dean (1987) was sensitive to fluctuations in energy dissipation and often predicted transport peaks that were not present in the data. The Watanabe (1992) equation, based on time-averaged bottom stress, predicted no transport at most laboratory locations. The Van Rijn (1993) model was comprehensive and required hydrodynamic, bedform, and sediment data. The model estimated the laboratory cross-shore distribution well, but greatly overestimated field transport. Seven models were developed in this study based on the principle that transported sediment is mobilized by the total shear stress acting on the bottom and transported by the current at that location. Shear stress, including the turbulent component, was calculated from the wave orbital velocity. Models 1 through 3 gave good estimates of the transport distribution, but underpredicted the transport peak near the plunging wave breakpoint. A suspension term was included in Models 4 through 7, which improved estimates near breaking for plunging breakers. Models 4, 5 and 7 also compared well to the field measurements. It was concluded that breaker type is an important variable in determining the amount of transport that occurs at a location. Lastly, inclusion of the turbulent component of the orbital velocity is vital in predictive sediment transport equations.

Smith, Ernest Ray

2006-08-01T23:59:59.000Z

31

An Intercomparison Study Using Electromagnetic Three-Component Turbulent Velocity Probes  

Science Conference Proceedings (OSTI)

An intercomparison study was performed with four Russian-made, electromagnetic probes capable of measuring three components of oceanic turbulent velocities and two single-axis velocity sensors familiar to western scientists, namely, a hot-film ...

David Y. Lai; Vadim T. Paka; Donald P. Delisi; Anatoli V. Arjannikov; Sergei A. Khanaev

2000-07-01T23:59:59.000Z

32

Gravity Surface Wave Bifurcation in a Highly Turbulent Swirling Flow  

E-Print Network (OSTI)

Gravity Surface Wave Bifurcation in a Highly Turbulent Swirling Flow Michael Baumer University Gravity Wave 2 3 Measurements 3 4 Mechanical Hardware: Problems and Solutions 5 5 Results 7 6 Conclusions investigated a free-surface gravity wave bifurcation in the large-separation regime, that is, where

Witten, Thomas A.

33

Internal Waves and Turbulence in the Antarctic Circumpolar Current  

Science Conference Proceedings (OSTI)

This study reports on observations of turbulent dissipation and internal wave-scale flow properties in a standing meander of the Antarctic Circumpolar Current (ACC) north of the Kerguelen Plateau. The authors characterize the intensity and spatial ...

Stephanie Waterman; Alberto C. Naveira Garabato; Kurt L. Polzin

2013-02-01T23:59:59.000Z

34

Turbulent Velocity-Variance Profiles in the Stable Boundary Layer Generated by a Nocturnal Low-Level Jet  

Science Conference Proceedings (OSTI)

Profiles of mean winds and turbulence were measured by the High Resolution Doppler lidar in the strong-wind stable boundary layer (SBL) with continuous turbulence. The turbulence quantity measured was the variance of the streamwise wind velocity ...

Robert M. Banta; Yelena L. Pichugina; W. Alan Brewer

2006-11-01T23:59:59.000Z

35

P wave velocity variations in the Coso region, California, derived...  

Open Energy Info (EERE)

P wave velocity variations in the Coso region, California, derived from local earthquake travel times Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal...

36

Mass Transport Velocity in Free Barotropic Poincaré Waves  

Science Conference Proceedings (OSTI)

The mass transport velocity induced by long surface waves in a shallow, rotating viscous ocean is studied theoretically by using a Lagrangian description of motion. The depth is constant, and the water is homogeneous. Such waves are referred to ...

Frode Hřydalsvik; Jan Erik Weber

2003-09-01T23:59:59.000Z

37

Perpendicular Ion Heating by Low-Frequency Alfven-Wave Turbulence in the Solar Wind  

E-Print Network (OSTI)

We consider ion heating by turbulent Alfven waves (AWs) and kinetic Alfven waves (KAWs) with perpendicular wavelengths comparable to the ion gyroradius and frequencies smaller than the ion cyclotron frequency. When the turbulence amplitude exceeds a certain threshold, an ion's orbit becomes chaotic. The ion then interacts stochastically with the time-varying electrostatic potential, and the ion's energy undergoes a random walk. Using phenomenological arguments, we derive an analytic expression for the rates at which different ion species are heated, which we test by simulating test particles interacting with a spectrum of randomly phased AWs and KAWs. We find that the stochastic heating rate depends sensitively on the quantity epsilon = dv/vperp, where vperp is the component of the ion velocity perpendicular to the background magnetic field B0, and dv (dB) is the rms amplitude of the velocity (magnetic-field) fluctuations at the gyroradius scale. In the case of thermal protons, when epsilon eps1, the proton ...

Chandran, Benjamin D G; Rogers, Barrett N; Quataert, Eliot; Germaschewski, Kai

2010-01-01T23:59:59.000Z

38

Effect of the Darrieus-Landau instability on turbulent flame velocity  

E-Print Network (OSTI)

Propagation of turbulent premixed flames influenced by the intrinsic hydrodynamic flame instability (the Darrieus-Landau instability) is considered in a two-dimensional case using the model nonlinear equation proposed recently. The nonlinear equation takes into account both influence of external turbulence and intrinsic properties of a flame front, such as small but finite flame thickness and realistically large density variations across the flame front. Dependence of the flame velocity on the turbulent length scale, on the turbulent intensity and on the density variations is investigated in the case of weak non-linearity and weak external turbulence. It is shown that the Darrieus-Landau instability influences the flamelet velocity considerably. The obtained results are in agreement with experimental data on turbulent burning of moderate values of the Reynolds number.

Maxim Zaytsev; Vitaliy Bychkov

2012-11-26T23:59:59.000Z

39

ARM - PI Product - Cloud-Scale Vertical Velocity and Turbulent Dissipation  

NLE Websites -- All DOE Office Websites (Extended Search)

ProductsCloud-Scale Vertical Velocity and Turbulent ProductsCloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send PI Product : Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals Site(s) NSA General Description Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May

40

Determining Turbulent Vertical Velocity, and Fluxes of Heat and Salt with an Autonomous Underwater Vehicle  

Science Conference Proceedings (OSTI)

The authors show that vertical turbulent fluxes in the upper ocean can be measured directly with an autonomous underwater vehicle (AUV). A horizontal profile of vertical water velocity is obtained by applying a Kalman smoother to AUV motion data. ...

Daniel R. Hayes; James H. Morison

2002-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

A Correction Method for Turbulence Measurements with a 3D Acoustic Doppler Velocity Profiler  

Science Conference Proceedings (OSTI)

A method is proposed to reduce the noise contribution to mean turbulence parameters obtained by 3D acoustic Doppler velocity profiler measurements. It is based on a noise spectrum reconstruction from cross-spectra evaluations of two independent ...

D. Hurther; U. Lemmin

2001-03-01T23:59:59.000Z

42

THE EFFECTS OF WAVE ESCAPE ON FAST MAGNETOSONIC WAVE TURBULENCE IN SOLAR FLARES  

Science Conference Proceedings (OSTI)

One of the leading models for electron acceleration in solar flares is stochastic acceleration by weakly turbulent fast magnetosonic waves ({sup f}ast waves{sup )}. In this model, large-scale flows triggered by magnetic reconnection excite large-wavelength fast waves, and fast-wave energy then cascades from large wavelengths to small wavelengths. Electron acceleration by large-wavelength fast waves is weak, and so the model relies on the small-wavelength waves produced by the turbulent cascade. In order for the model to work, the energy cascade time for large-wavelength fast waves must be shorter than the time required for the waves to propagate out of the solar-flare acceleration region. To investigate the effects of wave escape, we solve the wave kinetic equation for fast waves in weak turbulence theory, supplemented with a homogeneous wave-loss term. We find that the amplitude of large-wavelength fast waves must exceed a minimum threshold in order for a significant fraction of the wave energy to cascade to small wavelengths before the waves leave the acceleration region. We evaluate this threshold as a function of the dominant wavelength of the fast waves that are initially excited by reconnection outflows.

Pongkitiwanichakul, Peera; Chandran, Benjamin D. G. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Karpen, Judith T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); DeVore, C. Richard, E-mail: pbu3@unh.edu, E-mail: benjamin.chandran@unh.edu, E-mail: judy.karpen@nasa.gov, E-mail: devore@nrl.navy.mil [Naval Research Laboratory, Washington, DC 20375 (United States)

2012-09-20T23:59:59.000Z

43

Statistics of Shear and Turbulent Dissipation Profiles in Random Internal Wave Fields  

Science Conference Proceedings (OSTI)

Because breaking internal waves produces most of the turbulence in the thermocline, the statistics of ?, the rate of turbulent dissipation, cannot be understood apart from the statistics of internal wave shear. The statistics of ? and shear are ...

M. C. Gregg; H. E. Seim; D. B. Percival

1993-08-01T23:59:59.000Z

44

Gravity Wave Instability Dynamics at High Reynolds Numbers. Part II: Turbulence Evolution, Structure, and Anisotropy  

Science Conference Proceedings (OSTI)

This paper examines the character, intermittency, and anisotropy of turbulence accompanying wave instability, breaking, and turbulence evolution and decay for gravity waves (GW) having a high intrinsic frequency, amplitudes above and below ...

David C. Fritts; Ling Wang; Joe Werne; Tom Lund; Kam Wan

2009-05-01T23:59:59.000Z

45

The presence of interstellar turbulence could explain the velocity flattening in galaxies  

E-Print Network (OSTI)

Expanding our previous work on turbulent whirls [1] we have uncovered a similarity within the similarity shared by intense vortices. Using the new information we compress the tangential velocity profiles of a diverse set of vortices into one and thus identify those that belong to the same genus. Examining the Laser Doppler Anemometer (LDA) results of mechanically produced vortices and radar data of several tropical cyclones, we find that the uplift and flattening effect of tangential velocity is a consequence of turbulence. Reasoning by analogy we conclude that turbulence in the interstellar medium could indeed introduce a flattening effect in the galactic rotation curves.

Vatistas, Georgios H

2010-01-01T23:59:59.000Z

46

Excitation of Langmuir wave turbulence in high-frequency (HF) pump waves over Gakona, Alaska  

E-Print Network (OSTI)

(cont.) Investigated in this thesis are the excitation and observation of Langmuir wave turbulence caused by the parametric decay instability (PDI) in high-frequency space plasma heating experiments conducted at the NSF/DoD ...

Rokusek, Daniel L

2007-01-01T23:59:59.000Z

47

Shock wave / turbulent boundary layer interactions  

Science Conference Proceedings (OSTI)

This visualization shows the results of the simulation of a Mach 4 flow into two cone nosed cylindrical bodies adjacent to a flat plate. The analysis was computed with a Reynolds Averaged Navier Stokes (RANS) code utilizing a Spalart-Allmaras Turbulent ... Keywords: CFD, blender, raytracing, scientific visualization, visit, volume rendering

Michael A. Matheson; Allan D. Grosvenor; Alexander A. Zheltovodov

2011-11-01T23:59:59.000Z

48

Collisionless inter-species energy transfer and turbulent heating in drift wave turbulence  

Science Conference Proceedings (OSTI)

We reconsider the classic problems of calculating 'turbulent heating' and collisionless inter-species transfer of energy in drift wave turbulence. These issues are of interest for low collisionality, electron heated plasmas, such as ITER, where collisionless energy transfer from electrons to ions is likely to be significant. From the wave Poynting theorem at steady state, a volume integral over an annulus r{sub 1}heating as {integral}{sub r{sub 1}} {sup r{sub 2}} dr=-S{sub r}|{sub r{sub 1}{sup r{sub 2}}}{ne}0. Here S{sub r} is the wave energy density flux in the radial direction. Thus, a wave energy flux differential across an annular region indeed gives rise to a net heating, in contrast to previous predictions. This heating is related to the Reynolds work by the zonal flow, since S{sub r} is directly linked to the zonal flow drive. In addition to net heating, there is inter-species heat transfer. For collisionless electron drift waves, the total turbulent energy source for collisionless heat transfer is due to quasilinear electron cooling. Subsequent quasilinear ion heating occurs through linear ion Landau damping. In addition, perpendicular heating via ion polarization currents contributes to ion heating. Since at steady state, Reynolds work of the turbulence on the zonal flow must balance zonal flow frictional damping ({approx}{nu}{sub ii}{sup 2}{approx}|(e{phi}(tilde sign)/T)|{sup 4}), it is no surprise that zonal flow friction appears as an important channel for ion heating. This process of energy transfer via zonal flow has not previously been accounted for in analyses of energy transfer. As an application, we compare the rate of turbulent energy transfer in a low collisionality plasma with the rate of the energy transfer by collisions. The result shows that the collisionless turbulent energy transfer is a significant energy coupling process for ITER plasma.

Zhao, L. [Center for Astrophysics and Space Sciences and Department of Physics, University of California at San Diego, La Jolla, California 92093-0424 (United States); Diamond, P. H. [Center for Astrophysics and Space Sciences and Department of Physics, University of California at San Diego, La Jolla, California 92093-0424 (United States); WCI Center for Fusion Theory, National Fusion Research Institute, Gwahangno113, Yuseong-gu, Daejeon 305-333 (Korea, Republic of)

2012-08-15T23:59:59.000Z

49

Gravity surface wave turbulence in a laboratory flume  

E-Print Network (OSTI)

We present experimental results for water wave turbulence excited by piston-like programmed wavemakers in a water flume with horisontal dimensions 6x12x1.5 meters. Our main finding is that for a wide range of excitation amplitudes the energy spectrum has a power-law scaling, $E_\\omega \\sim \\omega^{-\

Petr Denissenko; Sergei Lukaschuk; Sergey Nazarenko

2006-10-08T23:59:59.000Z

50

Structure of the mean velocity and turbulence in premixed axisymmetric acetylene flames  

Science Conference Proceedings (OSTI)

Laser-Doppler measurements of axial mean velocities and the corresponding rms values of turbulent velocity fluctuations are reported for premixed, axisymmetric, acetylene flames together with the probability density distributions of the turbulent velocity fluctuations. All this information provides an insight into the structure of the flow field. Characteristic zones of the flow field are defined that show common features for all acetylene flames studied by the authors. These features are discussed in the paper and are suggested to characterize, in general, interesting parts of the flames.

Matovic, M.; Oka, S. (Inst. for Thermal Engineering and Energy Research, Beograd (Yugoslavia)); Durst, F. (Univ. Erlangen-Nuernberg, Erlangen (Germany). Lehrstuhl fuer Stroemungsmechanik)

1994-09-01T23:59:59.000Z

51

Experimental Study of Energy Transfer by Inertial Waves During the Build up of Turbulence in a Rotating System  

E-Print Network (OSTI)

We study the transition from fluid at rest to turbulence in a rotating water cylinder. We show that the energy, injected at a given height, is transported by inertial wave packets through the fluid volume. These waves propagate at velocities consistent with those calculated from linearized theory, even when they possess large amplitudes. A clear "front" in the temporal evolution of the energy power spectrum is detected, defining a time scale for energy transport at the linear wave speed in the system. Nonlinear energy transfer between modes is governed by a different time scale that can be much longer than the linear one. These observations suggest that the energy distribution and statistics in rotating turbulent fields that are driven by intermittent energy sources may be different from those described by the inverse energy cascade in two-dimensional turbulence.

Kolvin, Itamar; Vardi, Yuval; Sharon, Eran

2008-01-01T23:59:59.000Z

52

On the Structure of the Velocity Field over Progressive Mechanically-Generated Water Waves  

Science Conference Proceedings (OSTI)

The structure of the velocity field over a propagating wave of fixed frequency is examined. The vertical and horizontal velocities were measured in a transformed Eulerian wave-following frame of reference in a wind-wave research facility at ...

Yiannis Alex Papadimitrakis; En Yun Hsu; Robert L. Street

1984-12-01T23:59:59.000Z

53

Detonation wave velocity and curvature of brass encased PBXN-111  

Science Conference Proceedings (OSTI)

Detonation velocities and wave front curvatures were measured for PBXN-111 charges encased in 5 mm thick brass tubes. In all the experiments (charge diameters from 19 to 47 mm) the brass case affected the detonation properties of PBXN-111. Steady detonation waves propagated in brass encased charges with diameters as small as 19 mm, which is about half of the unconfined failure diameter. The radii of curvature of the detonation waves at the center of the wave fronts ranged from 52 to 141 mm for charge diameters of 25 to 47 mm. The angles between the detonation wave fronts and the brass/charge interfaces were between 72 and 74 degrees. {copyright} {ital 1996 American Institute of Physics.}

Forbes, J.W.; Lemar, E.R. [Naval Surface Warfare Center, Indian Head Division, Silver Spring, Maryland 20903-5640 (United States)

1996-05-01T23:59:59.000Z

54

WaveTurbulence Interactions in a Breaking Mountain Wave CRAIG C. EPIFANIO AND TINGTING QIAN  

E-Print Network (OSTI)

-breaking calculations. Of particular interest are the turbulent heat and momentum fluxes in the breaking wave fluxes on grid spacing is considered by computing a series of ensembles with grid spacings ranging from L are mostly resolved, but with increasing grid spacing, the resolved-scale fluxes decline

55

Covariance statistics of turbulence velocity components for wind-energy-conversion system design-homogeneous, isotropic case  

DOE Green Energy (OSTI)

When designing a wind energy converison system (WECS), it may be necessary to take into account the distribution of wind across the disc of rotation. The specific engineering applications include structural strength, fatigue, and control. This wind distribution consists of two parts, namely that associated with the mean wind profile and that associated with the turbulence velocity fluctuation field. The work reported herein is aimed at the latter, namely the distribution of turbulence velocity fluctuations across the WECS disk of rotation. A theory is developed for the two-time covariance matrix for turbulence velocity vector components for wind energy conversion system (WECS) design. The theory is developed for homogeneous and iotropic turbulance with the assumption that Taylor's hypothesis is valid. The Eulerian turbulence velocity vector field is expanded about the hub of the WECS. Formulae are developed for the turbulence velocity vector component covariance matrix following the WECS blade elements. It is shown that upon specification of the turbulence energy spectrum function and the WECS rotation rate, the two-point, two-time covariance matrix of the turbulent flow relative to the WECS bladed elements is determined. This covariance matrix is represented as the sum of nonstationary and stationary contributions. Generalized power spectral methods are used to obtain two-point, double frequency power spectral density functions for the turbulent flow following the blade elements. The Dryden turbulence model is used to demonstrate the theory. A discussion of linear system response analysis is provided to show how the double frequency turbulence spectra might be used to calculate response spectra of a WECS to turbulent flow. Finally the spectrum of the component of turbulence normal to the WECS disc of rotation, following the blade elements, is compared with experimental results.

Fichtl, G.H.

1983-09-01T23:59:59.000Z

56

MHD Turbulence Revisited  

E-Print Network (OSTI)

Kraichnan (1965) proposed that MHD turbulence occurs as a result of collisions between oppositely directed Alfvén wave packets. Recent work has generated some controversy over the nature of non linear couplings between colliding Alfvén waves. We find that the resolution to much of the confusion lies in the existence of a new type of turbulence, intermediate turbulence, in which the cascade of energy in the inertial range exhibits properties intermediate between those of weak and strong turbulent cascades. Some properties of intermediate MHD turbulence are: (i) in common with weak turbulent cascades, wave packets belonging to the inertial range are long lived; (ii) however, components of the strain tensor are so large that, similar to the situation in strong turbulence, perturbation theory is not applicable; (iii) the breakdown of perturbation theory results from the divergence of neighboring field lines due to wave packets whose perturbations in velocity and magnetic fields are localized, but whose perturba...

Goldreich, P

1996-01-01T23:59:59.000Z

57

Shock-unsteadiness model applied to oblique shock wave/turbulent boundary-layer interaction  

Science Conference Proceedings (OSTI)

Reynolds-averaged Navier-Stokes prediction of shock wave/turbulent boundary layer interactions can yield significant error in terms of the size of the separation bubble. In many applications, this can alter the shock structure and the resulting surface ... Keywords: high-speed flows, separation bubble, shock-unsteadiness, turbulence modelling, turbulent boundary layer

Amjad Ali Pasha; Krishnendu Sinha

2008-09-01T23:59:59.000Z

58

An Algorithm for Forecasting Mountain Wave–Related Turbulence in the Stratosphere  

Science Conference Proceedings (OSTI)

A global mountain wave parameterization for prediction of wave-related displacements and turbulence is described. The parameterization is used with input from National Meteorological Center analyses of wind and temperature to examine small-scale ...

Julio T. Bacmeister; Paul A. Newman; Bruce L. Gary; K. Roland Chan

1994-06-01T23:59:59.000Z

59

Parallel electric field generation by Alfven wave turbulence  

E-Print Network (OSTI)

{This work aims to investigate the spectral structure of the parallel electric field generated by strong anisotropic and balanced Alfvenic turbulence in relation with the problem of electron acceleration from the thermal population in solar flare plasma conditions.} {We consider anisotropic Alfvenic fluctuations in the presence of a strong background magnetic field. Exploiting this anisotropy, a set of reduced equations governing non-linear, two-fluid plasma dynamics is derived. The low-$\\beta$ limit of this model is used to follow the turbulent cascade of the energy resulting from the non-linear interaction between kinetic Alfven waves, from the large magnetohydrodynamics (MHD) scales with $k_{\\perp}\\rho_{s}\\ll 1$ down to the small "kinetic" scales with $k_{\\perp}\\rho_{s} \\gg 1$, $\\rho_{s}$ being the ion sound gyroradius.} {Scaling relations are obtained for the magnitude of the turbulent electromagnetic fluctuations, as a function of $k_{\\perp}$ and $k_{\\parallel}$, showing that the electric field develops ...

Bian, N H; Brown, J C

2010-01-01T23:59:59.000Z

60

Turbulent Mixing due to Surface Waves Indicated by Remote Sensing of Suspended Particulate Matter and Its Implementation into Coupled Modeling of Waves, Turbulence, and Circulation  

Science Conference Proceedings (OSTI)

This paper studies the impact of the surface waves on the turbulent mixing. The satellite observations of suspended particulate matter (SPM) at the ocean surface as an indicator of turbulent quantities of the flow are used. In a water column, SPM ...

Andrey Pleskachevsky; Mikhail Dobrynin; Alexander V. Babanin; Heinz Günther; Emil Stanev

2011-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Convective cell generation by kinetic Alfven wave turbulence in the auroral ionosphere  

Science Conference Proceedings (OSTI)

Modulation of convective cells by kinetic Alfven wave (KAW) turbulence is investigated. The interaction is governed by a nonlinear dispersion relation for the convective cells. It is shown that KAW turbulence is disrupted by excitation of the large-scale convective motion through a resonant instability. Application of the results to the auroral ionosphere shows that cross-scale coupling of the KAW turbulence and convective cells plays an important role in the evolution of ionospheric plasma turbulence.

Zhao, J. S.; Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences 210008, Nanjing (China); Yu, M. Y. [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany); Lu, J. Y. [National Center for Space Weather, China Meteorology Administration 100081, Beijing (China)

2012-06-15T23:59:59.000Z

62

Observations of the Surf-Zone Turbulent Dissipation Rate  

Science Conference Proceedings (OSTI)

The contributions of surface (breaking wave) boundary layer (SBL) and bottom (velocity shear) boundary layer (BBL) processes to surf-zone turbulence is studied here. The turbulent dissipation rate ?, estimated on a 160-m-long cross-shore ...

Falk Feddersen

2012-03-01T23:59:59.000Z

63

Wave Breaking Dissipation Observed with “SWIFT” Drifters  

Science Conference Proceedings (OSTI)

Energy dissipation rates during ocean wave breaking are estimated from high-resolution profiles of turbulent velocities collected within 1 m of the surface. The velocity profiles are obtained from a pulse-coherent acoustic Doppler sonar on a wave-...

Jim Thomson

2012-12-01T23:59:59.000Z

64

Pulse-to-Pulse Coherent Doppler Measurements of Waves and Turbulence  

Science Conference Proceedings (OSTI)

This paper presents laboratory and field testing of a pulse-to-pulse coherent acoustic Doppler profiler for the measurement of turbulence in the ocean. In the laboratory, velocities and wavenumber spectra collected from Doppler and digital ...

Fabrice Veron; W. Kendall Melville

1999-11-01T23:59:59.000Z

65

Evidence of critical balance in kinetic Alfven wave turbulence simulations  

Science Conference Proceedings (OSTI)

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

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

2012-05-15T23:59:59.000Z

66

Quasilinear Evolution of Kinetic Alfven Wave Turbulence and Perpendicular Ion Heating in the Solar Wind  

E-Print Network (OSTI)

It is shown that the quasi-linear evolution of ion and electron distribution functions as result of wave-particle interaction of Kinetic Alfven Waves in the turbulent solar wind plasma leads to instability of long wavelength electromagnetic cyclotron waves and to an increase of the ion temperature perpendicular to the magnetic field.

Rudakov, L; Ganguli, G; Mithaiwala, M

2010-01-01T23:59:59.000Z

67

Alfven Wave Collisions, The Fundamental Building Block of Plasma Turbulence IV: Laboratory Experiment  

E-Print Network (OSTI)

Turbulence is a phenomenon found throughout space and astrophysical plasmas. It plays an important role in solar coronal heating, acceleration of the solar wind, and heating of the interstellar medium. Turbulence in these regimes is dominated by Alfven waves. Most turbulence theories have been established using ideal plasma models, such as incompressible MHD. However, there has been no experimental evidence to support the use of such models for weakly to moderately collisional plasmas which are relevant to various space and astrophysical plasma environments. We present the first experiment to measure the nonlinear interaction between two counterpropagating Alfven waves, which is the building block for astrophysical turbulence theories. We present here four distinct tests that demonstrate conclusively that we have indeed measured the daughter Alfven wave generated nonlinearly by a collision between counterpropagating Alfven waves.

Drake, D J; Howes, G G; Kletzing, C A; Skiff, F; Carter, T A; Auerbach, D W

2013-01-01T23:59:59.000Z

68

Transient Evolution of Langmuir Turbulence in Ocean Boundary Layers Driven by Hurricane Winds and Waves  

Science Conference Proceedings (OSTI)

A large-eddy simulation (LES) model, which adopts wave-averaged equations with vortex force, is used to investigate Langmuir turbulence and ocean boundary layer (OBL) dynamics in high-wind hurricane conditions. The temporally evolving spatially ...

Peter P. Sullivan; Leonel Romero; James C. McWilliams; W. Kendall Melville

2012-11-01T23:59:59.000Z

69

Near-Surface Characteristics of the Turbulence Structure during a Mountain-Wave Event  

Science Conference Proceedings (OSTI)

A case study of mountain-wave-induced turbulence observed during the Terrain-Induced Rotor Experiment (T-REX) in Owens Valley, California, is presented. During this case study, large spatial and temporal variability in aerosol backscatter ...

Željko Ve?enaj; Stephan F. J. De Wekker; Vanda Grubiši?

2011-05-01T23:59:59.000Z

70

Energy Deposition and Turbulent Dissipation Owing to Gravity Waves in the Mesosphere  

Science Conference Proceedings (OSTI)

An attempt is made to define the thermodynamics of internal gravity waves breaking in the middle atmosphere on the basis of the energy conservation law for finite fluid volumes. Consistent with established turbulence theory, this method ...

Erich Becker; Gerhard Schmitz

2002-01-01T23:59:59.000Z

71

Investigations of the cascade of Langmuir wave turbulence over HAARP Observatory in Gakona, Alaska  

E-Print Network (OSTI)

This thesis investigates the cascade lines from Langmuir wave turbulence as a result of Parametric Decay Instability (PDI) in the ionosphere. This effect is studied using a high-frequency (HF) heater located at the NSF/DoD ...

Burton, Laura M

2007-01-01T23:59:59.000Z

72

Mountain Wave Signatures in MODIS 6.7-?m Imagery and Their Relation to Pilot Reports of Turbulence  

Science Conference Proceedings (OSTI)

A technique for nowcasting turbulent mountain waves over the Front Range of the state of Colorado is investigated using Moderate Resolution Imaging Spectroradiometer (MODIS) water vapor (6.7 ?m) channel imagery. Pilot reports of turbulence were ...

N. L. Uhlenbrock; K. M. Bedka; W. F. Feltz; S. A. Ackerman

2007-06-01T23:59:59.000Z

73

HIERARCHICAL STRUCTURE OF MAGNETOHYDRODYNAMIC TURBULENCE IN POSITION-POSITION-VELOCITY SPACE  

SciTech Connect

Magnetohydrodynamic turbulence is able to create hierarchical structures in the interstellar medium (ISM) that are correlated on a wide range of scales via the energy cascade. We use hierarchical tree diagrams known as dendrograms to characterize structures in synthetic position-position-velocity (PPV) emission cubes of isothermal magnetohydrodynamic turbulence. We show that the structures and degree of hierarchy observed in PPV space are related to the presence of self-gravity and the global sonic and Alfvenic Mach numbers. Simulations with higher Alfvenic Mach number, self-gravity and supersonic flows display enhanced hierarchical structure. We observe a strong dependency on the sonic and Alfvenic Mach numbers and self-gravity when we apply the statistical moments (i.e., mean, variance, skewness, kurtosis) to the leaf and node distribution of the dendrogram. Simulations with self-gravity, larger magnetic field and higher sonic Mach number have dendrogram distributions with higher statistical moments. Application of the dendrogram to three-dimensional density cubes, also known as position-position-position (PPP) cubes, reveals that the dominant emission contours in PPP and PPV are related for supersonic gas but not for subsonic. We also explore the effects of smoothing, thermal broadening, and velocity resolution on the dendrograms in order to make our study more applicable to observational data. These results all point to hierarchical tree diagrams as being a promising additional tool for studying ISM turbulence and star forming regions for obtaining information on the degree of self-gravity, the Mach numbers and the complicated relationship between PPV and PPP data.

Burkhart, Blakesley; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, 475 N. Charter St., WI 53711 (United States); Goodman, Alyssa [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Rosolowsky, Erik [University of British Columbia, Okanagan Campus, 3333 University Way, Kelowna BC V1V 1V7 (Canada)

2013-06-20T23:59:59.000Z

74

Observations of Turbulence Mixing and Vorticity in a Littoral Surface Boundary Layer  

Science Conference Proceedings (OSTI)

Measurements of small-scale vorticity, turbulence velocity, and dissipation rates of turbulence kinetic energy ? were taken in a littoral fetch-limited surface wave boundary layer. Drifters deployed on the surface formed convergence streaks with ...

R-C. Lien; B. Sanford; W-T. Tsai

2008-03-01T23:59:59.000Z

75

Determination of the Rate of Dissipation of Turbulent Energy from Simultaneous Temperature and Velocity Shear Microstructure Measurements  

Science Conference Proceedings (OSTI)

Spectra of turbulence have been examined for both temperature gradient and velocity shear. The data for this comparison are 10–15 m segments of vertical microstructure profiles (at depths of 5–100 m) obtained during the 1978 Joint Air Sea ...

N. S. Oakey

1982-03-01T23:59:59.000Z

76

Turbulence and Gravity Waves within an Upper-Level Front  

Science Conference Proceedings (OSTI)

High-resolution dropwindsonde and in-flight measurements collected by a research aircraft during the Severe Clear-Air Turbulence Colliding with Aircraft Traffic (SCATCAT) experiment and simulations from numerical models are analyzed for a clear-...

Steven E. Koch; Brian D. Jamison; Chungu Lu; Tracy L. Smith; Edward I. Tollerud; Cecilia Girz; Ning Wang; Todd P. Lane; Melvyn A. Shapiro; David D. Parrish; Owen R. Cooper

2005-11-01T23:59:59.000Z

77

Simulations of observed lee-waves and rotor turbulence  

Science Conference Proceedings (OSTI)

On 18 November 2008 a commercial aircraft encountered severe turbulence while flying in westerly flow along the southeastern coast of Iceland and descending from 2.500 m down to the ground for a safe landing. Numerical simulations at horizontal ...

Hálfdán Ágústsson; Haraldur Ólafsson

78

Ion-acoustic turbulence in a nonmonochromatic pump wave  

SciTech Connect

A theoretical study is made of the development of a steady-state turbulent condition in an unbounded homogeneous plasma due to a high-frequency electric field. (AIP)

Aliev, Y.M.; Gradov, O.M.; Izmailov, G.N.

1977-05-01T23:59:59.000Z

79

Ionized gas velocity dispersion in nearby dwarf galaxies: looking at supersonic turbulent motions  

E-Print Network (OSTI)

We present the results of ionized gas turbulent motions study in several nearby dwarf galaxies using a scanning Fabry-Perot interferometer with the 6-m telescope of the SAO RAS. Combining the `intensity-velocity dispersion' diagrams (I-sigma) with two-dimensional maps of radial velocity dispersion we found a number of common patterns pointing to the relation between the value of chaotic ionized gas motions and processes of current star formation. In five out of the seven analysed galaxies we identified expanding shells of ionized gas with diameters of 80-350 pc and kinematic ages of 1-4 Myr. We also demonstrate that the I-sigma diagrams may be useful for the search of supernova remnants, other small expanding shells or unique stars in nearby galaxies. As an example, a candidate luminous blue variable (LBV) was found in UGC 8508. We propose some additions to the interpretation, previously used by Munoz-Tunon et al. to explain the I-sigma diagrams for giant star formation regions. In the case of dwarf galaxies,...

Moiseev, Alexei

2012-01-01T23:59:59.000Z

80

Impact of Breaking Wave Form Drag on Near-Surface Turbulence and Drag Coefficient over Young Seas at High Winds  

Science Conference Proceedings (OSTI)

The effects of breaking waves on near-surface wind turbulence and drag coefficient are investigated using large-eddy simulation. The impact of intermittent and transient wave breaking events (over a range of scales) is modeled as localized form ...

Nobuhiro Suzuki; Tetsu Hara; Peter P. Sullivan

2013-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Correlation of turbulent burning velocities of ethanol-air, measured in a fan-stirred bomb up to 1.2 MPa  

SciTech Connect

The turbulent burning velocity is defined by the mass rate of burning and this also requires that the associated flame surface area should be defined. Previous measurements of the radial distribution of the mean reaction progress variable in turbulent explosion flames provide a basis for definitions of such surface areas for turbulent burning velocities. These inter-relationships. in general, are different from those for burner flames. Burning velocities are presented for a spherical flame surface, at which the mass of unburned gas inside it is equal to the mass of burned gas outside it. These can readily be transformed to burning velocities based on other surfaces. The measurements of the turbulent burning velocities presented are the mean from five different explosions, all under the same conditions. These cover a wide range of equivalence ratios, pressures and rms turbulent velocities for ethanol-air mixtures. Two techniques are employed, one based on measurements of high speed schlieren images, the other on pressure transducer measurements. There is good agreement between turbulent burning velocities measured by the two techniques. All the measurement are generalised in plots of burning velocity normalised by the effective unburned gas rms velocity as a function of the Karlovitz stretch factor for different strain rate Markstein numbers. For a given value of this stretch factor a decrease in Markstein number increases the normalised burning velocity. Comparisons are made with the findings of other workers. (author)

Bradley, D.; Lawes, M.; Mansour, M.S. [School of Mechanical Engineering, University of Leeds (United Kingdom)

2011-01-15T23:59:59.000Z

82

Alfven Wave Collisions, The Fundamental Building Block of Plasma Turbulence II: Numerical Solution  

E-Print Network (OSTI)

This paper presents the numerical verification of an asymptotic analytical solution for the nonlinear interaction between counterpropagating Alfven waves, the fundamental building block of astrophysical plasma turbulence. The analytical solution, derived in the weak turbulence limit using the equations of incompressible MHD, is compared to a nonlinear gyrokinetic simulation of an Alfven wave collision. The agreement between these methods signifies that the incompressible solution satisfactorily describes the essential dynamics of the nonlinear energy transfer, even under the weakly collisional plasma conditions relevant to many astrophysical environments.

Nielson, Kevin D; Dorland, William

2013-01-01T23:59:59.000Z

83

P wave velocity variations in the Coso region, California, derived from  

Open Energy Info (EERE)

P wave velocity variations in the Coso region, California, derived from P wave velocity variations in the Coso region, California, derived from local earthquake travel times Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: P wave velocity variations in the Coso region, California, derived from local earthquake travel times Details Activities (1) Areas (1) Regions (0) Abstract: Inversion of 4036 P wave travel time residuals from 429 local earthquakes using a tomographic scheme provides information about three-dimensional upper crustal velocity variations in the Indian Wells Valley-Coso region of southeastern California. The residuals are calculated relative to a Coso-specific velocity model, corrected for station elevation, weighted, and back-projected along their ray paths through models defined with layers of blocks. Slowness variations in the surface

84

Effects of CO/sub 2/ flooding on wave velocities in rocks with hydrocarbons  

SciTech Connect

Compressional and shear-wave velocities were measured in the laboratory in seven sandstones (porosities ranging from 6 to 29%) and one unconsolidated sand (37% porosity) saturated with n-hexadecane (C/sub 16/H/sub 34/) both before and after CO/sub 2/ flooding. CO/sub 2/ flooding decreased compressional-wave velocities significantly, while shear-wave velocities were less affected. The magnitude of these effects was found to depend on confining and pore pressures, temperature, and porosities of the rocks. The experimental results and theoretical analysis show that the decreases in compressional-wave velocities caused by CO/sub 2/ flooding may be seismically resolvable in situ. Therefore, seismic--especially high-frequency, high-resolution seismic--methods may be useful in mapping and locating CO/sub 2/ zones, tracking movements of CO/sub 2/ fronts, and monitoring flooding processes in reservoirs undergoing CO/sub 2/ flooding.

Wang, Z. (Core Labs., Calgary (CA)); Nur, A.M. (Stanford Univ., Geophysics Dept., CA (US))

1989-11-01T23:59:59.000Z

85

Three-dimensional P and S waves velocity structures of the Coso geothermal  

Open Energy Info (EERE)

P and S waves velocity structures of the Coso geothermal P and S waves velocity structures of the Coso geothermal area, California, from microseismic travel time data Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Three-dimensional P and S waves velocity structures of the Coso geothermal area, California, from microseismic travel time data Details Activities (1) Areas (1) Regions (0) Abstract: High precision P and S wave travel times for 2104 microearthquakes with focus <6 km are used in a non-linear inversion to derive high-resolution three-dimensional compressional and shear velocity structures at the Coso Geothermal Area in eastern California. Block size for the inversion is 0.2 km horizontally and 0.5 km vertically and inversions are investigated in the upper 5 km of the geothermal area.

86

The upper crustal P-wave velocity structure of Newberry volcano, Central Oregon.  

E-Print Network (OSTI)

?? The upper-crustal seismic-velocity structure of Newberry volcano, central Oregon, is imaged using P-wave travel time tomography. The inversion combines a densely-spaced seismic line collected… (more)

Beachly, Matthew William

2011-01-01T23:59:59.000Z

87

The Upper Crustal P-wave Velocity Structure of Newberry Volcano, Central Oregon.  

E-Print Network (OSTI)

??The upper-crustal seismic-velocity structure of Newberry volcano, central Oregon, is imaged using P-wave travel time tomography. The inversion combines a densely-spaced seismic line collected in… (more)

Beachly, Matthew William, 1986-

2011-01-01T23:59:59.000Z

88

Sources of Gravity Wave Activity Seen in the Vertical Velocities Observed by the Flatland VHF Radar  

Science Conference Proceedings (OSTI)

Observations of vertical velocity made with the Flatland VHF radar located in the extremely flat terrain near Champaign, Illinois, are used to study sources of enhanced variance. The variance is used as an indicator of gravity wave activity. In ...

G. D. Nastrom; M. R. Peterson; J. L. Green; K. S. Gage; T. E. VanZandt

1990-08-01T23:59:59.000Z

89

Effect of an Insoluble Surface Film on the Drift Velocity of Capillary–Gravity Waves  

Science Conference Proceedings (OSTI)

The drift velocity due to capillary-gravity waves in a deep ocean is investigated theoretically. The surface is covered by an insoluble, inextensible film, and the analysis is based an a Lagrangian description of motion. Attenuated as well as ...

Jan Erik Weber; Even Fřrland

1989-07-01T23:59:59.000Z

90

Turbulent spectra from three drift-wave interactions  

SciTech Connect

Hydrodynamic equations for the drift-wave instability containing the {rvec E} {times} {rvec B} convective nonlinearity are used to show that the three wave interactions lead to temporal chaos with broad-band frequency spectra in the saturated state. 7 refs., 2 figs.

Terry, P.W.; Horton, W.

1982-02-01T23:59:59.000Z

91

MODEL FOR ALFVEN WAVE TURBULENCE IN SOLAR CORONAL LOOPS: HEATING RATE PROFILES AND TEMPERATURE FLUCTUATIONS  

Science Conference Proceedings (OSTI)

It has been suggested that the solar corona may be heated by dissipation of Alfven waves that propagate up from the solar photosphere. According to this theory, counterpropagating Alfven waves are subject to nonlinear interactions that lead to turbulent decay of the waves and heating of the chromospheric and coronal plasma. To test this theory, better models for the dynamics of Alfven waves in coronal loops are required. In this paper, we consider wave heating in an active region observed with the Solar Dynamics Observatory in 2010 May. First a three-dimensional (3D) magnetic model of the region is constructed, and ten magnetic field lines that match observed coronal loops are selected. For each loop we construct a 3D magnetohydrodynamic model of the Alfven waves near the selected field line. The waves are assumed to be generated by footpoint motions inside the kilogauss magnetic flux elements at the two ends of the loop. Based on such models, we predict the spatial and temporal profiles of the heating along the selected loops. We also estimate the temperature fluctuations resulting from such heating. We find that the Alfven wave turbulence model can reproduce the observed characteristics of the hotter loops in the active region core, but the loops at the periphery of the region have large expansion factors and are predicted to be thermally unstable.

Asgari-Targhi, M.; Van Ballegooijen, A. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS-15, Cambridge, MA 02138 (United States)

2012-02-10T23:59:59.000Z

92

Effect of temperature on wave velocities in sands and sandstones with heavy hydrocarbons  

SciTech Connect

A laboratory investigation was made of the effects of temperature on wave velocities in sandstones and unconsolidated sand saturated with heavy hydrocarbons. The large decreases of the compressional and shear velocities in such sandstones and sand with increasing temperature suggest that seismic methods may be very useful in detecting heat fronts in heavy hydrocarbon reservoirs undergoing steamflooding or in-situ combustion.

Wang, Z.; Nur, A.

1988-02-01T23:59:59.000Z

93

Electromagnetic plane waves with negative phase velocity in charged black strings  

SciTech Connect

We investigate the propagation regions of electromagnetic plane waves with negative phase velocity in the ergosphere of static charged black strings. For such a propagation, some conditions for negative phase velocity are established that depend on the metric components and the choice of the octant. We conclude that these conditions remain unaffected by the negative values of the cosmological constant.

Sharif, M., E-mail: msharif.math@pu.edu.pk; Manzoor, R., E-mail: rubabmanzoor9@yahoo.com [University of the Punjab, Department of Mathematics (Pakistan)

2013-02-15T23:59:59.000Z

94

Effect of wave boundary layer on sea-to-air dimethylsulfide transfer velocity during typhoon passage  

E-Print Network (OSTI)

: Dimethylsulfide; Sea-to-air gas transfer velocity; Wave boundary layer; Tropical cyclone; Drag coefficient in order to accurately calculate aerosol radiative forcing. The sea-to-air DMS flux depends on airside coefficient CD and roughness length z0 has been investigated over small areas of the sea or in wave tanks

Chu, Peter C.

95

On the Group-Velocity Property for Wave-Activity Conservation Laws  

Science Conference Proceedings (OSTI)

The density and the flux of wave-activity conservation laws are generally required to satisfy the group-velocity property: under the WKB approximation (i.e., for nearly monochromatic small-amplitude waves in a slowly varying medium), the flux ...

J. Vanneste; T. G. Shepherd

1998-03-01T23:59:59.000Z

96

MHD Turbulence Revisited  

E-Print Network (OSTI)

Kraichnan (1965) proposed that MHD turbulence occurs as a result of collisions between oppositely directed Alfv\\'en wave packets. Recent work has generated some controversy over the nature of non linear couplings between colliding Alfv\\'en waves. We find that the resolution to much of the confusion lies in the existence of a new type of turbulence, intermediate turbulence, in which the cascade of energy in the inertial range exhibits properties intermediate between those of weak and strong turbulent cascades. Some properties of intermediate MHD turbulence are: (i) in common with weak turbulent cascades, wave packets belonging to the inertial range are long lived; (ii) however, components of the strain tensor are so large that, similar to the situation in strong turbulence, perturbation theory is not applicable; (iii) the breakdown of perturbation theory results from the divergence of neighboring field lines due to wave packets whose perturbations in velocity and magnetic fields are localized, but whose perturbations in displacement are not; (iv) 3--wave interactions dominate individual collisions between wave packets, but interactions of all orders $n\\geq 3$ make comparable contributions to the intermediate turbulent energy cascade; (v) successive collisions are correlated since wave packets are distorted as they follow diverging field lines; (vi) in common with the weak MHD cascade, there is no parallel cascade of energy, and the cascade to small perpendicular scales strengthens as it reaches higher wave numbers; (vii) For an appropriate weak excitation, there is a natural progression from a weak, through an intermediate, to a strong cascade.

P. Goldreich; S. Sridhar

1996-12-31T23:59:59.000Z

97

Spectra of Baroclinic Inertia-Gravity Wave Turbulence  

Science Conference Proceedings (OSTI)

Baroclinic inertia–gravity (IG) waves form a persistent background of thermocline depth and sea surface height oscillations. They also contribute to the kinetic energy of horizontal motions in the subsurface layer. Measured by the ratio of water ...

Roman E. Glazman

1996-07-01T23:59:59.000Z

98

Wave Breaking and Transition to Turbulence in Stratified Shear Flows  

Science Conference Proceedings (OSTI)

In a previous study the authors used a nonlinear, compressible, spectral collocation numerical model to examine the evolution of a breaking gravity wave in two and three dimensions. The present paper extends that effort to examine the ...

David C. Fritts; James F. Garten; Řyvind Andreassen

1996-04-01T23:59:59.000Z

99

Wave-Turbulence Dynamics in the Stably Stratified Boundary Layer  

Science Conference Proceedings (OSTI)

New data obtained at the Boulder Atmospheric Observatory (BAO) has been compared with a linear stability analysis of the background atmospheric state as measured by rawinsonde ascents. Good agreement was obtained between measured wave parameters ...

F. Einaudi; J. J. Finnigan

1993-07-01T23:59:59.000Z

100

Group velocity of extraordinary waves in superdense magnetized quantum plasma with spin-1/2 effects  

Science Conference Proceedings (OSTI)

Based on the one component plasma model, a new dispersion relation and group velocity of elliptically polarized extraordinary electromagnetic waves in a superdense quantum magnetoplasma are derived. The group velocity of the extraordinary wave is modified due to the quantum forces and magnetization effects within a certain range of wave numbers. It means that the quantum spin-1/2 effects can reduce the transport of energy in such quantum plasma systems. Our work should be of relevance for the dense astrophysical environments and the condensed matter physics.

Li Chunhua; Ren Haijun; Yang Weihong [Department of Modern Physics, University of Science and Technology of China, 230026 Hefei (China); Wu Zhengwei [Department of Modern Physics, University of Science and Technology of China, 230026 Hefei (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2012-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Shear wave velocities from noise correlation at local scale  

Science Conference Proceedings (OSTI)

Cross correlations of ambient seismic noise recordings have been studied to infer shear seismic velocities with depth. Experiments have been done in the crowded and noisy historical centre of Napoli over inter-station distances from 50 m to about 400 m, whereas active seismic spreadings are prohibitive, even for just one receiver. Group velocity dispersion curves have been extracted with FTAN method from the noise cross correlations and then the non linear inversion of them has resulted in Vs profiles with depth. The information of near by stratigraphies and the range of Vs variability for samples of Neapolitan soils and rocks confirms the validity of results obtained with our expeditious procedure. Moreover, the good comparison of noise H/V frequency of the first main peak with 1D and 2D spectral amplifications encourages to continue experiments of noise cross-correlation. If confirmed in other geological settings, the proposed approach could reveal a low cost methodology to obtain reliable and detailed Vs velocity profiles.

De Nisco, G.; Nunziata, C. [Dipartimento di Scienze della Terra, Univ. Napoli Federico II (Italy); Vaccari, F. [Dipartimento di Scienze della Terra, Univ. Trieste (Italy); Panza, G. F. [Dipartimento di Scienze della Terra, Univ. Trieste (Italy); The Abdus Salam International Center for Theoretical Physics, ESP-SAND Group, Trieste (Italy)

2008-07-08T23:59:59.000Z

102

Transition to Turbulence and Effect of Initial Conditions on 3D Compressible Mixing in Planar Blast-wave-driven Systems  

Science Conference Proceedings (OSTI)

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams, 9(2), 209 (1991)] are presented. Using the multi-physics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J.A. Greenough, J. Comp. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pre-transition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernova are discussed.

Miles, A R; Edwards, M J; Greenough, J A

2004-11-08T23:59:59.000Z

103

The Interaction between an Internal Gravity Wave and Turbulence in the Stably-Stratified Nocturnal Boundary Layer  

Science Conference Proceedings (OSTI)

Observations have been made of a stably-stratified nighttime boundary layer perturbed by Kelvin-Helmholtz internal waves with critical levels around 600 m. Significant turbulence intensities were measured although the time-mean gradient ...

J. J. Finnigan; F. Einaudi; D. Fua

1984-08-01T23:59:59.000Z

104

Structure and Generation of Turbulence at Interfaces Strained by Internal Solitary Waves Propagating Shoreward over the Continental Shelf  

Science Conference Proceedings (OSTI)

Detailed observations of the structure within internal solitary waves propagating shoreward over Oregon's continental shelf reveal the evolving nature of interfaces as they become unstable and break, creating turbulent flow. A persistent feature ...

J. N. Moum; D. M. Farmer; W. D. Smyth; L. Armi; S. Vagle

2003-10-01T23:59:59.000Z

105

A Free-Floating PIV System: Measurements of Small-Scale Turbulence under the Wind Wave Surface  

Science Conference Proceedings (OSTI)

An in situ free-floating underwater miniature particle image velocimetry (UWMPIV) system is developed and applied to measure the structure of turbulence in the aqueous side of the wind wave surface boundary layer. The UWMPIV system provides a ...

Binbin Wang; Qian Liao; Jianen Xiao; Harvey A. Bootsma

2013-07-01T23:59:59.000Z

106

THE SLOW-MODE NATURE OF COMPRESSIBLE WAVE POWER IN SOLAR WIND TURBULENCE  

Science Conference Proceedings (OSTI)

We use a large, statistical set of measurements from the Wind spacecraft at 1 AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to show that the compressible component of inertial range solar wind turbulence is primarily in the kinetic slow mode. The zero-lag cross-correlation C({delta}n, {delta}B{sub ||}) between proton density fluctuations {delta}n and the field-aligned (compressible) component of the magnetic field {delta}B{sub ||} is negative and close to -1. The typical dependence of C({delta}n, {delta}B{sub ||}) on the ion plasma beta {beta}{sub i} is consistent with a spectrum of compressible wave energy that is almost entirely in the kinetic slow mode. This has important implications for both the nature of the density fluctuation spectrum and for the cascade of kinetic turbulence to short wavelengths, favoring evolution to the kinetic Alfven wave mode rather than the (fast) whistler mode.

Howes, G. G.; Klein, K. G.; TenBarge, J. M. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Bale, S. D.; Chen, C. H. K.; Salem, C. S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

2012-07-01T23:59:59.000Z

107

The Bolus Velocity in the Stochastic Theory of Ocean Turbulent Tracer Transport  

Science Conference Proceedings (OSTI)

A stochastic theory of tracer transport in compressible turbulence has recently been developed and then applied to the ocean case because stratified flow in isopycnal coordinates is analogous to compressible flow with the isopycnal layer ...

John K. Dukowicz; Richard J. Greatbatch

1999-09-01T23:59:59.000Z

108

High Resolution Measurements of Turbulence, Velocity and Stress Using a Pulse-to-Pulse Coherent Sonar  

Science Conference Proceedings (OSTI)

Considered are the capabilities of a recently developed pulse-to-pulse coherent sonar called the High Resolution Current Profiler (HRCP). Special emphasis is placed on methods whereby reliable and accurate vertical profiles of turbulence ...

Atle Lohrmann; Bruce Hackett; Lars Petter Rřed

1990-02-01T23:59:59.000Z

109

Lidar measurement of wind velocity turbulence spectra encountered by a rotating turbine blade  

DOE Green Energy (OSTI)

A homodyne CO/sub 2/ lidar system beam was conically scanned around a horizontal axis to measure the wind speed and turbulence characteristics encountered by a rotating turbine blade. Turbulence spectra obtained from the scanning lidar differed considerably from those calculated from fixed-point anemometer measurements, showing a redistribution of energy from lower to higher frequencies. The differences appeared more pronounced during periods when the atmosphere was stable.

Hardesty, R.M.; Korrell, J.A.; Hall, F.F. Jr.

1982-01-01T23:59:59.000Z

110

Dependence of Turbulent and Mesoscale Velocity Variances on Scale and Stability  

Science Conference Proceedings (OSTI)

The scale dependence of velocity variances is studied using data collected from a grassland site, a heather site, and four forested sites. The dependence of velocity variances on averaging time, used to define the fluctuation quantities, is ...

L. Mahrt; Erin Moore; Dean Vickers; N. O. Jensen

2001-03-01T23:59:59.000Z

111

Electromagnetic wave propagation with negative phase velocity in regular black holes  

SciTech Connect

We discuss the propagation of electromagnetic plane waves with negative phase velocity in regular black holes. For this purpose, we consider the Bardeen model as a nonlinear magnetic monopole and the Bardeen model coupled to nonlinear electrodynamics with a cosmological constant. It turns out that the region outside the event horizon of each regular black hole does not support negative phase velocity propagation, while its possibility in the region inside the event horizon is discussed.

Sharif, M., E-mail: msharif.math@pu.edu.pk; Manzoor, R., E-mail: rubabmanzoor9@yahoo.com [University of the Punjab, Department of Mathematics (Pakistan)

2012-12-15T23:59:59.000Z

112

Effect of temperature on wave velocities in sands and sandstones with heavy hydrocarbons  

SciTech Connect

A laboratory investigation was made of the effects of temperature on wave velocities in well cemented Massillon and Boise sandstones and unconsolidated Ottawa sand saturated with heavy hydrocarbons, as well as the dependence of compressional velocities in the hydrocarbons themselves as a function of temperature. The hydrocarbons selected as pore saturants were a commercial paraffin wax, 1-Eicosene, natural heavy crude, and natural tar. The experimental results show that the compressional wave velocities in the hydrocarbons decrease markedly with increasing temperature. In contrast wave velocities in the Massillon and Boise sandstones and unconsolidated Ottawa sand saturated with air or water decrease only little with increasing temperatures. The main reason for the large decreases in rocks with hydrocarbons is the melting of solid hydrocarbons, and high pore pressure. Thermal expansion of the saturants, and possibly thermal cracking of the heavy fractions and vaporization of the light fractions of the hydrocarbons may also contribute. The large decreases of the compressional and shear wave velocities in the hydrocarbon-saturated rocks and sands with temperature, suggest that seismic measurements such as used in seismology or borehole tomography may be very useful in detecting steam fronts in heavy hydrocarbon reservoirs undergoing steam flooding.

Wang, Z.; Nur, A.M.

1986-01-01T23:59:59.000Z

113

Nonlinear pulse propagation and phase velocity of laser-driven plasma waves  

Science Conference Proceedings (OSTI)

Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.

Schroeder, Carl B.; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

2011-03-25T23:59:59.000Z

114

Velocity  

Science Conference Proceedings (OSTI)

... Delta t ffl \\Delta t = 1ns. Pulse-Dri ven Wall Motion ( ff = ... varies, can increase (!), eventually decays tozero. Pulse-Dri ven Domain Wall Velocity ( ff = ...

2004-01-16T23:59:59.000Z

115

On Energy Flux and Group Velocity of Waves in Baroclinic Flows  

Science Conference Proceedings (OSTI)

A modified energy flux is defined by adding a nondivergent term that involves ? to the traditional energy flux. The resultant flux, when normalized by the total eddy energy, is exactly equal to the group velocity of Rossby waves on a ? plane with ...

Edmund K. M. Chang; Isidoro Orlanski

1994-12-01T23:59:59.000Z

116

Increase of shear wave velocity before the 1998 eruption of Merapi volcano (Indonesia)  

E-Print Network (OSTI)

Increase of shear wave velocity before the 1998 eruption of Merapi volcano (Indonesia) U. Wegler,1 of the edifice of Merapi volcano (Java, Indonesia) before its eruption in 1998 by analyzing multiply scattered eruption of Merapi volcano (Indonesia), Geophys. Res. Lett., 33, L09303, doi:10.1029/2006GL025928. 1

Snieder, Roel

117

Climatology of Velocity and Temperature Turbulence Statistics Determined from Rawinsonde and ACARS/AMDAR Data  

Science Conference Proceedings (OSTI)

The climatology of the spatial structure functions of velocity and temperature for various altitudes (pressure levels) and latitude bands is constructed from the global rawinsonde network and from Aircraft Communications, Addressing, and ...

Rod Frehlich; Robert Sharman

2010-06-01T23:59:59.000Z

118

Energy- and flux-budget turbulence closure model for stably stratified flows. Part II: the role of internal gravity waves  

E-Print Network (OSTI)

We advance our prior energy- and flux-budget turbulence closure model (Zilitinkevich et al., 2007, 2008) for the stably stratified atmospheric flows and extend it accounting for additional vertical flux of momentum and additional productions of turbulent kinetic energy, turbulent potential energy (TPE) and turbulent flux of potential temperature due to large-scale internal gravity waves (IGW). Main effects of IGW are following: the maximal value of the flux Richardson number (universal constant 0.2-0.25 in the no-IGW regime) becomes strongly variable. In the vertically homogeneous stratification, it increases with increasing wave energy and can even exceed 1. In the heterogeneous stratification, when IGW propagate towards stronger stratification, the maximal flux Richardson number decreases with increasing wave energy, reaches zero and then becomes negative. In other words, the vertical flux of potential temperature becomes counter-gradient. IGW also reduce anisotropy of turbulence and increase the share of TPE in the turbulent total energy. Depending on the direction (downward or upward), IGW either strengthen or weaken the total vertical flux of momentum. Predictions from the proposed model are consistent with available data from atmospheric and laboratory experiments, direct numerical simulations and large-eddy simulations.

S. S. Zilitinkevich; T. Elperin; N. Kleeorin; V. L'vov; I. Rogachevskii

2009-05-11T23:59:59.000Z

119

Velocity and Timing of Multiple Spherically Converging Shock Waves in Liquid Deuterium  

Science Conference Proceedings (OSTI)

The fuel entropy and required drive energy for an inertial confinement fusion implosion are set by a sequence of shocks that must be precisely timed to achieve ignition. This Letter reports measurements of multiple spherical shock waves in liquid deuterium that facilitate timing inertial confinement fusion shocks to the required precision. These experiments produced the highest shock velocity observed in liquid deuterium (U{sub s}=135 km/s at {approx}2500 GPa) and also the first observation of convergence effects on the shock velocity. Simulations model the shock-timing results well when a nonlocal transport model is used in the coronal plasma.

Boehly, T. R.; Goncharov, V. N.; Seka, W.; Hu, S. X.; Marozas, J. A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Barrios, M. A.; Celliers, P. M.; Hicks, D. G.; Collins, G. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Departments of Mechanical Engineering and Physics, University of Rochester, Rochester, New York 14623 (United States)

2011-05-13T23:59:59.000Z

120

ON THE AMPLIFICATION OF MAGNETIC FIELD BY A SUPERNOVA BLAST SHOCK WAVE IN A TURBULENT MEDIUM  

SciTech Connect

We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the 'rippled' shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

Guo Fan; Li Shengtai; Li Hui; Li, David [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Giacalone, Joe; Jokipii, J. R. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States)

2012-03-10T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Turbulence  

NLE Websites -- All DOE Office Websites (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

122

An empirical model for the mean-velocity profiles of a turbulent boundary layer under the effects of surface curvature  

E-Print Network (OSTI)

An empirical model has been developed to predict the mean-velocity profile of a turbulent boundary layer under the influence of surface curvature. The model proposed is able to determine the profiles for both a convex and concave curvature. This was possible by employing the inviscid term, C,, which not only distinguishes the convex profiles from the concave profiles but its usage allows for a better prediction of these profiles. The model has been applied to experimental data from Schobeiri and Pardivala (1991) available from Texas A&M test facility. Along with these sets of data, experimental data from published literature such as So and Mellor (1973) and Kestoras and Simon (1993) have been employed in verifying the model. For all the cases, the model demonstrated a relatively high degree of accuracy in predicting the measured mean-velocity of the boundary layer and the estimated skin-friction coefficients. A skinfriction coefficient correlation has also been determined. C, is shown to affect the skinfriction coefficients in these cases.

Huynh, Long Quang

1994-01-01T23:59:59.000Z

123

Wave-Turbulence interactions in the Upper Ocean. Part I: The Energy Balance of the Interacting Fields of Surface Wind Waves and Wind-Induced Three-Dimensional Turbulence  

Science Conference Proceedings (OSTI)

We analyze in detail the budget of total and fluctuating energy in the surface layer of the ocean. We suggest a rational scheme for separating the budget of turbulence from that of random wind-generated surface waves, and suggest in particular a ...

S. A. Kitaigorodskii; J. L. Lumley

1983-11-01T23:59:59.000Z

124

Turbulence in the sub-Alfv\\'enic solar wind driven by reflection of low-frequency Alfv\\'en waves  

E-Print Network (OSTI)

We study the formation and evolution of a turbulent spectrum of Alfv\\'en waves driven by reflection off the solar wind density gradients, starting from the coronal base up to 17 solar radii, well beyond the Alfv\\'enic critical point. The background solar wind is assigned and 2D shell models are used to describe nonlinear interactions. We find that the turbulent spectra are influenced by the nature of reflected waves. Close to the base, these give rise to a flatter and steeper spectrum for the outgoing and reflected waves respectively. At higher heliocentric distance both spectra evolve toward an asymptotic Kolmogorov spectrum. The turbulent dissipation is found to account for at least half of the heating required to sustain the background imposed solar wind and its shape is found to be determined by the reflection-determined turbulent heating below 1.5 solar radii. Therefore reflection and reflection-driven turbulence are shown to play a key role in the accelerationof the fast solar wind and origin of the tur...

Verdini, A; Buchlin, E

2009-01-01T23:59:59.000Z

125

EPRI (2004, 2006) Ground-Motion Model (GMM) Review Project: Shear Wave Velocity Measurements at Seismic Recording Stations  

Science Conference Proceedings (OSTI)

This report presents the results of site characterization studies for the EPRI (2004, 2006) Ground-Motion Model Review Project. The primary purpose of this investigation was to develop S-wave velocity (VS) profiles to a depth of 30 m, or more, and to estimate the average shear wave velocity of the upper 30 m (VS30) at thirty three (33) seismic instrument sites located in the Central and Eastern United States. Results are presented in individual seismic recording station site ...

2013-04-15T23:59:59.000Z

126

Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles  

DOE Patents (OSTI)

An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

Benjamin, Robert F. (315 Rover Blvd., Los Alamos, NM 87544)

1987-01-01T23:59:59.000Z

127

Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles  

DOE Patents (OSTI)

An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

Benjamin, R.F.

1983-10-18T23:59:59.000Z

128

Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles  

DOE Patents (OSTI)

An apparatus is disclosed for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously. 3 figs.

Benjamin, R.F.

1987-03-10T23:59:59.000Z

129

Section 1: Interfacial Turbulence and AirWater Scalar Transfer Turbulence and wave dynamics across gasliquid interfaces 1  

E-Print Network (OSTI)

The calculation of the gas transfer between the ocean and atmosphere13 S.A. Kitaigorodskii The influence of wind relationship to airwater gas transfer rates51 D. Turney, S. Banerjee Turbulent gas flux measurements near the airwater interface in an oscillating-grid tank 65 J.G. Janzen, H.E. Schulz, G.H. Jirka Sensible and latent

Takada, Shoji

130

High-resolution seismic tomography of compressional wave velocity structure at Newberry Volcano, Oregon Cascade Range  

SciTech Connect

Compressional wave velocity structure is determined for the upper crust beneath Newberry Volcano, central Oregon, using a high-resolution active-source seismic-tomography method. Newberry Volcano is a bimodal shield volcano east of the axis of the Cascade Range. It is associated both with the Cascade Range and with northwest migrating silicic volcanism in southeast Oregon. High-frequency (approx.7 Hz) crustal phases, nominally Pg and a midcrustal reflected phase, travel upward through a target volume beneath Newberry Volcano to a dense array of 120 seismographs. This arrangement is limited by station spacing to 1- to 2-km resolution in the upper 5 to 6 km of the crust beneath the volcano's summit caldera. The experiment tests the hypothesis that Cascade Range volcanoes are underlain only by small magma chambers. A small low-velocity anomaly delineated abosut 3 km below the summit caldera supports this hypothesis for Newberry Volcano and is interpreted as a possible magma chamber of a few to a few tens of km/sup 3/ in volume. A ring-shaped high-velocity anomaly nearer the surface coincides with the inner mapped ring fractures of the caldera. It also coincides with a circular gravity high, and we interpret it as largely subsolidus silicic cone sheets. The presence of this anomaly and of silicic vents along the ring fractures suggests that the fractures are a likely eruption path between the small magma chamber and the surface.

Achauer, U.; Evans, J.R.; Stauber, D.A.

1988-09-10T23:59:59.000Z

131

On the Fluid Dynamical Theory of Turbulent Gas Transfer Across an Air-Sea Interface in the Presence of Breaking Wind-Waves  

Science Conference Proceedings (OSTI)

It is shown that in order to describe the transfer of gases in the liquid near the air-sea interface, the vertical structure of three-dimensional small-scale turbulence in turbulent patches generated by breaking waves must be considered. The ...

S. A. Kitaigorodskii

1984-05-01T23:59:59.000Z

132

Transition to turbulence and effect of initial conditions on three-dimensional compressible mixing in planar blast-wave-driven systems  

Science Conference Proceedings (OSTI)

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional (3D) numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pretransition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernovae are discussed.

Miles, A.R.; Blue, B.; Edwards, M.J.; Greenough, J.A.; Hansen, J.F.; Robey, H.F.; Drake, R.P.; Kuranz, C.; Leibrandt, D.R. [Lawrence Livermore National Laboratory, L-021, 7000 East Avenue, P.O. Box 808, Livermore, California 94551 (United States); University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109 (United States)

2005-05-15T23:59:59.000Z

133

Fiber optic sensor for detecting damage location and shock wave velocity  

DOE Patents (OSTI)

This invention is comprised of a shock velocity and damage location sensor providing a means of measuring shock speed and damage location. The sensor consists of a long series of time-of-arrival `points` constructed with fiber optics. The fiber optic sensor apparatus measures shock velocity as the fiber sensor is progressively crushed as a shock wave proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the shock. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the `points` of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of reflection planes distributed along the fibers length. In this configuration, as the shock front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the shock wave destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor.

Weiss, J.D.

1993-12-31T23:59:59.000Z

134

MEASUREMENT OF COMPRESSIONAL-WAVE SEISMIC VELOCITIES IN 29 WELLS AT THE HANFORD SITE  

Science Conference Proceedings (OSTI)

Check shot seismic velocity surveys were collected in 100 B/C, 200 East, 200-PO-1 Operational Unit (OU), and the Gable Gap areas in order to provide time-depth correlation information to aid the interpretation of existing seismic reflection data acquired at the Hanford Site (Figure 1). This report details results from 5 wells surveyed in fiscal year (FY) 2008, 7 wells in FY 2009, and 17 wells in FY 2010 and provides summary compressional-wave seismic velocity information to help guide future seismic survey design as well as improve current interpretations of the seismic data (SSC 1979/1980; SGW-39675; SGW-43746). Augmenting the check shot database are four surveys acquired in 2007 in support of the Bechtel National, Inc. Waste Treatment Plant construction design (PNNL-16559, PNNL-16652), and check shot surveys in three wells to support seismic testing in the 200 West Area (Waddell et al., 1999). Additional sonic logging was conducted during the late 1970s and early 1980s as part of the Basalt Waste Isolation Program (BWIP) (SSC 1979/1980) and check shot/sonic surveys as part of the safety report for the Skagit/Hanford Nuclear project (RDH/10-AMCP-0164). Check shot surveys are used to obtain an in situ measure of compressional-wave seismic velocity for sediment and rock in the vicinity of the well point, and provide the seismic-wave travel time to geologic horizons of interest. The check shot method deploys a downhole seismic receiver (geophone) to record the arrival of seismic waves generated by a source at the ground surface. The travel time of the first arriving seismic-wave is determined and used to create a time-depth function to correlate encountered geologic intervals with the seismic data. This critical tie with the underlying geology improves the interpretation of seismic reflection profile information. Fieldwork for this investigation was conducted by in house staff during the weeks of September 22, 2008 for 5 wells in the 200 East Area (Figure 2); June 1, 2009 for 7 wells in the 200-PO-1 OU and Gable Gap regions (see Figure 3 and Figure 4); and March 22, 2010 and April 19, 2010 for 17 wells in the 200 East, The initial scope of survey work was planned for Wells 299-EI8-1, 699-2-E14, 699-12-18, 699-16-51, 699-42-30, 699-53-55B, 699-54-18D, and 699-84-34B. Well 299-E18-1 could not be entered due to bent casing (prevented removal of the pump), wells 699-12-18 and 699-42-30 could not be safely reached by the logging truck, Well 699-16-51 was decommissioned prior to survey start, Well 699-53-55B did not have its pump pulled, and Wells 699-2-EI4, 699-54-18D, and 699-84-34B are artesian and capped with an igloo structure. Table 1 provides a list of wells that were surveyed and Figure 1 through Figure 5 show the well locations relative to the Hanford Site.

PETERSON SW

2010-10-08T23:59:59.000Z

135

Correlations of whitecap coverage and gas transfer velocity with microwave brightness temperature for plunging and spilling breaking waves  

DOE Green Energy (OSTI)

Bubbles and bubble plumes generated by wind-induced breaking waves significantly enhance the gas exchange across the interface between the ocean and atmosphere under high-wind conditions. Whitcaps, or active spilling wave crests, are the sea-surface manifestation of the bubbles and bubble plumes in the subsurface mixed layer, and the fractional area of the sea surface covered by which has been proposed to correlate linearly with the air-sea gas transfer velocity. The presence of whitecaps substantially increases the microwave brightness temperature of the sea surface. It could be possible to estimate the whitecap coverage from the sea-surface microwave brightness temperature would also be very helpful in developing a remote-sensing model for predicting air-sea gas transfer velocities from microwave brightness temperatures. As a part of an air-water gas exchange experiment conducted in an outdoor surf pool, measurements were made that were designed to investigate the correlation between whitecap coverage and microwave brightness temperature. A mechanical wave maker was located at the deep end of the pool and the generated waves propagate and break towards the shallow end of the pool. Two wave patterns characteristic of plunging and spilling breaking waves at four wave heights from 0.3 m to 1.2 m were produced.

Wang, Qin; Monahan, E.C. [Connecticut Univ., Groton, CT (United States). Marine Sciences Inst.; Asher, W.E. [Battelle/Marine Sciences Lab., Sequim, WA (United States); Smith, P.M. [Naval Research Lab. Detachment, Stennis Space Center, MS (United States)

1995-07-01T23:59:59.000Z

136

Derivation of site-specific relationships between hydraulic parameters and p-wave velocities based on hydraulic and seismic tomography  

SciTech Connect

In this study, hydraulic and seismic tomographic measurements were used to derive a site-specific relationship between the geophysical parameter p-wave velocity and the hydraulic parameters, diffusivity and specific storage. Our field study includes diffusivity tomograms derived from hydraulic travel time tomography, specific storage tomograms, derived from hydraulic attenuation tomography, and p-wave velocity tomograms, derived from seismic tomography. The tomographic inversion was performed in all three cases with the SIRT (Simultaneous Iterative Reconstruction Technique) algorithm, using a ray tracing technique with curved trajectories. The experimental set-up was designed such that the p-wave velocity tomogram overlaps the hydraulic tomograms by half. The experiments were performed at a wellcharacterized sand and gravel aquifer, located in the Leine River valley near Göttingen, Germany. Access to the shallow subsurface was provided by direct-push technology. The high spatial resolution of hydraulic and seismic tomography was exploited to derive representative site-specific relationships between the hydraulic and geophysical parameters, based on the area where geophysical and hydraulic tests were performed. The transformation of the p-wave velocities into hydraulic properties was undertaken using a k-means cluster analysis. Results demonstrate that the combination of hydraulic and geophysical tomographic data is a promising approach to improve hydrogeophysical site characterization.

Brauchler, R.; Doetsch, J.; Dietrich, P.; Sauter, M.

2012-01-10T23:59:59.000Z

137

Estimating Wind Velocities in Mountain Lee Waves Using Sailplane Flight Data  

Science Conference Proceedings (OSTI)

Mountain lee waves are a form of atmospheric gravity wave that is generated by flow over mountain topography. Mountain lee waves are of considerable interest, because they can produce drag that affects the general circulation, windstorms, and ...

R. P. Millane; G. D. Stirling; R. G. Brown; N. Zhang; V. L. Lo; E. Enevoldson; J. E. Murray

2010-01-01T23:59:59.000Z

138

Nonlinear Evolution of an Upward Propagating Gravity Wave: Overturning, Convection, Transience and Turbulence  

Science Conference Proceedings (OSTI)

A numerical simulation of the nonlinear evolution of an upward propagating gravity wave shows that over-turning (the turning over of isopotential temperature surfaces) is the mechanism responsible for limiting the growth of the wave. Wave ...

R. L. Walterscheid; G. Schubert

1990-01-01T23:59:59.000Z

139

A Numerical Study of Gravity Wave Breaking and Impacts on Turbulence and Mean State  

Science Conference Proceedings (OSTI)

A model system is established that includes three interactive components: a dynamics model, a turbulence model, and a chemistry model. The dynamics model solves the two-dimensional, nonlinear, nonhydrostatic, compressible, and viscous flow ...

H-L. Liu; P. B. Hays; R. G. Roble

1999-07-01T23:59:59.000Z

140

The Influence of Whitecapping Waves on the Vertical Structure of Turbulence in a Shallow Estuarine Embayment  

Science Conference Proceedings (OSTI)

The vertical distribution of the turbulent kinetic energy dissipation rate was measured using an array of four acoustic Doppler velocimeters in the shallow embayment of Grizzly Bay, San Francisco Bay, California. Owing to the combination of wind ...

Nicole L. Jones; Stephen G. Monismith

2008-07-01T23:59:59.000Z

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141

Surface Wave–Turbulence Interactions. Scaling ?(z) near the Sea Surface  

Science Conference Proceedings (OSTI)

A freely rising profiler was used to collect vertical microstructure profiles in the upper oceanic boundary layer under various atmospheric and sea conditions. Near the sea surface, the rate of viscous dissipation of turbulence kinetic energy, ?, ...

A. Anis; J. N. Moum

1995-09-01T23:59:59.000Z

142

Measurements of plasma temperature in indirect drive targets from the shock wave velocity in aluminum in the Iskra-5 facility  

Science Conference Proceedings (OSTI)

Results are presented from the development of a method for measuring plasma temperature in indirect (X-ray) drive targets by recording the shock wave velocity in the Iskra-5 facility. The samples under investigation were irradiated by X-rays in a converter box, and the shock wave velocity was determined from the time at which the wave reached the back surface of the sample and the surface began to emit visible radiation. This emission, in turn, was detected by a streak camera. The results of experiments on the interaction of X radiation with a hot dense plasma, as well as the accompanying gas-dynamic processes in aluminum samples, are analyzed both theoretically and numerically. In experiments with Al and Pb samples, the shock wave velocity was measured to vary in the range U = 8-35 km/s, and the range of variation of the temperature of the box walls was measured to be T{sub e} = 140-170 eV.

Vatulin, V. V.; Zhidkov, N. V.; Kravchenko, A. G.; Kuznetsov, P. G.; Litvin, D. N.; Mis'ko, V. V.; Pinegin, A. V.; Pleteneva, N. P.; Senik, A. V.; Starodubtsev, K. V.; Tachaev, G. V. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (Russian Federation)

2010-05-15T23:59:59.000Z

143

Shear Wave Velocity Structure of Southern African Crust: Evidence for Compositional Heterogeneity within Archaean and Proterozoic Terrains  

Science Conference Proceedings (OSTI)

Crustal structure in southern Africa has been investigated by jointly inverting receiver functions and Rayleigh wave group velocities for 89 broadband seismic stations spanning much of the Precambrian shield of southern Africa. 1-D shear wave velocity profiles obtained from the inversion yield Moho depths that are similar to those reported in previous studies and show considerable variability in the shear wave velocity structure of the lower part of the crust between some terrains. For many of the Archaean and Proterozoic terrains in the shield, S velocities reach 4.0 km/s or higher over a substantial part of the lower crust. However, for most of the Kimberley terrain and adjacent parts of the Kheis Province and Witwatersrand terrain, as well as for the western part of the Tokwe terrain, mean shear wave velocities of {le} 3.9 km/s characterize the lower part of the crust along with slightly ({approx}5 km) thinner crust. These findings indicate that the lower crust across much of the shield has a predominantly mafic composition, except for the southwest portion of the Kaapvaal Craton and western portion of the Zimbabwe Craton, where the lower crust is intermediate-to-felsic in composition. The parts of the Kaapvaal Craton underlain by intermediate-to-felsic lower crust coincide with regions where Ventersdorp rocks have been preserved, and thus we suggest that the intermediate-to-felsic composition of the lower crust and the shallower Moho may have resulted from crustal melting during the Ventersdorp tectonomagmatic event at c. 2.7 Ga and concomitant crustal thinning caused by rifting.

Kgaswane, E M; Nyblade, A A; Julia, J; Dirks, P H H M; Durrheim, R J; Pasyanos, M E

2008-11-11T23:59:59.000Z

144

Advances in Fluid Modeling of the Solar Wind. Part 1: Electron and Anisotropic Proton Temperatures from the Collisionless Dissipation of Alfven Wave Turbulence  

E-Print Network (OSTI)

We develop a 1D solar-wind model that includes separate energy equations for the electrons and protons, proton temperature anisotropy, collisional and collisionless heat flux, and an analytical treatment of low-frequency, reflection-driven, Alfven-wave turbulence. To partition the turbulent heating between electron heating, parallel proton heating, and perpendicular proton heating, we employ results from the theories of linear wave damping and nonlinear stochastic heating. We account for mirror and oblique firehose instabilities by increasing the proton pitch-angle scattering rate when the proton temperature anisotropy exceeds the threshold for either instability. We numerically integrate the equations of the model forward in time until a steady state is reached, focusing on two fast-solar-wind-like solutions. These solutions are consistent with a number of observations, supporting the idea that Alfven-wave turbulence plays an important role in the origin of the solar wind.

Chandran, Benjamin D G; Quataert, Eliot; Bale, Stuart D

2011-01-01T23:59:59.000Z

145

Turbulence Structure of the Convective Boundary Layer. Part III: The Vertical Velocity Budgets of Thermals and Their Environment  

Science Conference Proceedings (OSTI)

The dynamics of thermal updrafts and compensating environmental downdrafts in the convective boundary layer are examined using observations from the Phoenix 78 field experiment. Separate vertical velocity budgets are presented for thermal ...

George S. Young

1988-07-01T23:59:59.000Z

146

Crust and upper mantle P wave velocity structure beneath Valles caldera, New Mexico: Results from the Jemez teleseismic tomography experiment  

Science Conference Proceedings (OSTI)

New results are presented from the teleseismic component of the Jemez Tomography Experiment conducted across Valles caldera in northern New Mexico. We invert 4872 relative {ital P} wave arrival times recorded on 50 portable stations to determine velocity structure to depths of 40 km. The three principle features of our model for Valles caldera are: (1) near-surface low velocities of {minus}17{percent} beneath the Toledo embayment and the Valle Grande, (2) midcrustal low velocities of {minus}23{percent} in an ellipsoidal volume underneath the northwest quadrant of the caldera, and (3) a broad zone of low velocities ({minus}15{percent}) in the lower crust or upper mantle. Crust shallower than 20 km is generally fast to the northwest of the caldera and slow to the southeast. Near-surface low velocities are interpreted as thick deposits of Bandelier tuff and postcaldera volcaniclastic rocks. Lateral variation in the thickness of these deposits supports increased caldera collapse to the southeast, beneath the Valle Grande. We interpret the midcrustal low-velocity zone to contain a minimum melt fraction of 10{percent}. While we cannot rule out the possibility that this zone is the remnant 1.2 Ma Bandelier magma chamber, the eruption history and geochemistry of the volcanic rocks erupted in Valles caldera following the Bandelier tuff make it more likely that magma results from a new pulse of intrusion, indicating that melt flux into the upper crust beneath Valles caldera continues. The low-velocity zone near the crust-mantle boundary is consistent with either partial melt in the lower crust or mafic rocks without partial melt in the upper mantle. In either case, this low-velocity anomaly indicates that underplating by mantle-derived melts has occurred. {copyright} 1998 American Geophysical Union

Steck, Lee K.; Fehler, Michael C.; Roberts, Peter M.; Baldridge, W. Scott; Stafford, Darrik G. [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Lutter, William J.; Sessions, Robert [Department of Geology and Geophysics, University of Wisconsin-Madison (United States)

1998-10-01T23:59:59.000Z

147

Calculating Reynolds Stresses from ADCP Measurements in the Presence of Surface Gravity Waves Using the Cospectra-Fit Method  

Science Conference Proceedings (OSTI)

Recently, the velocity observations of acoustic Doppler current profilers (ADCPs) have been successfully used to estimate turbulent Reynolds stresses in estuaries and tidal channels. However, the presence of surface gravity waves can ...

Anthony R. Kirincich; Steven J. Lentz; Gregory P. Gerbi

2010-05-01T23:59:59.000Z

148

The Coupling of Gravity Waves and Turbulence at White Sands, New Mexico, from VHF Radar Observations  

Science Conference Proceedings (OSTI)

Doppler spectra taken with the VHF Doppler radar at White Sands Missile Range are used to describe the winds and turbulence for 10 days in March?April 1991. The large power aperture product of this radar provides excellent data coverage in 150-m ...

G. D. Nastrom; F. D. Eaton

1993-01-01T23:59:59.000Z

149

INCORPORATING KINETIC PHYSICS INTO A TWO-FLUID SOLAR-WIND MODEL WITH TEMPERATURE ANISOTROPY AND LOW-FREQUENCY ALFVEN-WAVE TURBULENCE  

Science Conference Proceedings (OSTI)

We develop a one-dimensional solar-wind model that includes separate energy equations for the electrons and protons, proton temperature anisotropy, collisional and collisionless heat flux, and an analytical treatment of low-frequency, reflection-driven, Alfven-wave (AW) turbulence. To partition the turbulent heating between electron heating, parallel proton heating, and perpendicular proton heating, we employ results from the theories of linear wave damping and nonlinear stochastic heating. We account for mirror and oblique firehose instabilities by increasing the proton pitch-angle scattering rate when the proton temperature anisotropy exceeds the threshold for either instability. We numerically integrate the equations of the model forward in time until a steady state is reached, focusing on two fast-solar-wind-like solutions. These solutions are consistent with a number of observations, supporting the idea that AW turbulence plays an important role in the origin of the solar wind.

Chandran, Benjamin D. G.; Dennis, Timothy J. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Quataert, Eliot [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States); Bale, Stuart D., E-mail: benjamin.chandran@unh.edu, E-mail: tim.dennis@unh.edu, E-mail: eliot@astro.berkeley.edu, E-mail: bale@ssl.berkeley.edu [Physics Department and Space Sciences Laboratory, 311 Old LeConte Hall, University of California, Berkeley, CA 94720 (United States)

2011-12-20T23:59:59.000Z

150

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

151

Rossby Wave Frequencies and Group Velocities for Finite Element and Finite Difference Approximations to the Vorticity-Divergence and the Primitive Forms of the Shallow Water Equations  

Science Conference Proceedings (OSTI)

In this paper Rossby wave frequencies and group velocities are analyzed for various finite element and finite difference approximations to the vorticity-divergence form of the shallow water equations. Also included are finite difference solutions ...

Beny Neta; R. T. Williams

1989-07-01T23:59:59.000Z

152

Four Lectures on Turbulent Combustion  

E-Print Network (OSTI)

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

Peters, Norbert

153

One dimensional P wave velocity structure of the crust beneath west Java and accurate hypocentre locations from local earthquake inversion  

SciTech Connect

A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299 Degree-Sign were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquake locations and represents a further step toward more detailed seismotectonic studies in this area of West Java.

Supardiyono; Santosa, Bagus Jaya [Physics Department, Faculty of Mathematics and Natural Sciences, State University of Surabaya, Surabaya (Indonesia) and Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia); Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia)

2012-06-20T23:59:59.000Z

154

A Systematic Search for Trapped Equatorial Waves in the GATE Velocity Data  

Science Conference Proceedings (OSTI)

Moored current meter data taken over a 60-day period during GATE (GARP Atlantic Tropical Experiment) near the equator at 28°W, have been systematically searched for vertically propagating equatorially trapped waves. Three independent tests ...

A. M. Horigan; R. H. Weisberg

1981-04-01T23:59:59.000Z

155

Turbulent Mixing Processes in Atmospheric Bores and Solitary Waves Deduced from Profiling Systems and Numerical Simulation  

Science Conference Proceedings (OSTI)

Families of solitary waves (“solitons”) associated with two atmospheric bores on the same day were observed by an unprecedented number of ground-based and airborne profiling systems during the International H2O Project (IHOP). In addition, a very ...

Steven E. Koch; Wayne Feltz; Frédéric Fabry; Mariusz Pagowski; Bart Geerts; Kristopher M. Bedka; David O. Miller; James W. Wilson

2008-04-01T23:59:59.000Z

156

Estimating fracture parameters from p-wave velocity profiles about a geothermal well  

DOE Green Energy (OSTI)

The feasibility of locating fracture zones and estimating their crack parameters was examined using an areal well shoot method centered on Utah State Geothermal Well 9-1, Beaver County, Utah. High-resolution travel time measurements were made between a borehole sensor and an array of shot stations distributed radially and azimuthally about the well. Directional velocity behavior in the vicinity of the well was investigated by comparing velocity logs derived from the travel time data. Three fracture zones were identified form the velocity data, corroborating fracture indicators seen in other geophysical logs conducted in Well 9-1. Crack densities and average crack aspect ratios for these fracture zones were estimated using a self-consistent velocity theory (O'Connell and Budiansy 1974). Probable trends of these fracture zones were established from a combination of the data from the more distant shot stations and the results of a gravity survey. The results of this study indicate that the areal well shoot is a potentially powerful tool for the reconnaisance of fracture-controlled fluid and gas reservoirs. Improvements in methodology and hardware could transform it into an operationally viable survey method.

Jenkinson, J.T.; Henyey, T.L.; Sammis, C.G.; Leary, P.C.; McRaney, J.K.

1981-12-01T23:59:59.000Z

157

Electrostatic drift-wave instability in a nonuniform quantum magnetoplasma with parallel velocity shear flows  

SciTech Connect

The propagation of high and low frequency (in comparison with the cyclotron frequency) electrostatic drift-waves is investigated in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel shear flow, by employing the quantum magnetohydrodynamic (QMHD) model. Using QMHD model, a new set of equations is presented in order to investigate linear properties of electrostatic drift-waves with sheared plasma flows for dense plasmas. In this regard, dispersion relations for coupled electron-thermal and drift-ion acoustic modes are derived and several interesting limiting cases are discussed. For instance, it is found that sheared ion flow parallel to the external magnetic field can drive the quantum drift-ion acoustic wave unstable, etc. The present investigation may have relevance in dense astrophysical environments where quantum effects are significant.

Tariq, Sabeen; Mirza, Arshad M. [Department of Physics, Theoretical Plasma Physics Group, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Masood, W. [Theoretical Plasma Physics Division, PINSTECH, P.O. Box. Nilore, Islamabad 44000, Pakistan and National Center for Physics (NCP), Islamabad 45320 (Pakistan)

2010-10-15T23:59:59.000Z

158

Some Influences of Background Flow Conditions on the Generation of Turbulence due to Gravity Wave Breaking above Deep Convection  

Science Conference Proceedings (OSTI)

Deep moist convection generates turbulence in the clear air above and around developing clouds, penetrating convective updrafts and mature thunderstorms. This turbulence can be due to shearing instabilities caused by strong flow deformations near ...

Todd P. Lane; Robert D. Sharman

2008-11-01T23:59:59.000Z

159

Imaging earth's interior: Tomographic inversions for mantle P-wave velocity structure  

SciTech Connect

A formalism is developed for the tomographic inversion of seismic travel time residuals. The travel time equations are solved both simultaneously, for velocity model terms and corrections to the source locations, and progressively, for each set of terms in succession. The methods differ primarily in their treatment of source mislocation terms. Additionally, the system of equations is solved directly, neglecting source terms. The efficacy of the algorithms is explored with synthetic data as we perform simulations of the general procedure used to produce tomographic images of Earth's mantle from global earthquake data. The patterns of seismic heterogeneity in the mantle that would be returned reliably by a tomographic inversion are investigated. We construct synthetic data sets based on real ray sampling of the mantle by introducing spherical harmonic patterns of velocity heterogeneity and perform inversions of the synthetic data.

Pulliam, R.J.

1991-07-01T23:59:59.000Z

160

Observing Groups of Solitary Internal Waves and Turbulence with BATFISH and Echo-Sounder  

Science Conference Proceedings (OSTI)

Acoustic backscatter from a 200 kHz echo-sounder and temperature fine-structure from a towed CTD (BAT-FISH) am compared prior to and during the passage of a group of large-amplitude internal waves on the continental shelf off Nova Scotia. The ...

H. Sandstrom; J. A. Elliot; N. A. Cchrane

1989-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Dissipation and Heating in Supersonic Hydrodynamic and MHD Turbulence  

E-Print Network (OSTI)

We study energy dissipation and heating by supersonic MHD turbulence in molecular clouds using Athena, a new higher-order Godunov code. We analyze the dependence of the saturation amplitude, energy dissipation characteristics, power spectra, sonic scaling, and indicators of intermittency in the turbulence on factors such as the magnetic field strength, driving scale, energy injection rate, and numerical resolution. While convergence in the energies is reached at moderate resolutions, we find that the power spectra require much higher resolutions that are difficult to obtain. In a 1024^3 hydro run, we find a power law relationship between the velocity dispersion and the spatial scale on which it is measured, while for an MHD run at the same resolution we find no such power law. The time-variability and temperature intermittency in the turbulence both show a dependence on the driving scale, indicating that numerically driving turbulence by an arbitrary mechanism may not allow a realistic representation of these properties. We also note similar features in the power spectrum of the compressive component of velocity for supersonic MHD turbulence as in the velocity spectrum of an initially-spherical MHD blast wave, implying that the power law form does not rule out shocks, rather than a turbulent cascade, playing a significant role in the regulation of energy transfer between spatial scales.

M. Nicole Lemaster; James M. Stone

2008-09-23T23:59:59.000Z

162

Lidar Measurement of Turbulence Encountered by Horizontal-Axis Wind Turbines  

Science Conference Proceedings (OSTI)

We used a continuous-wave (CW) Doppler lidar to measure wind velocity turbulence from a moving frame of reference. By directing the lidar beam to trace the perimeters of vertical-plane disks about horizontal axes parallel to the mean wind ...

R. M. Hardesty; B. F. Weber

1987-03-01T23:59:59.000Z

163

Residual energy in magnetohydrodynamic turbulence and in the solar wind  

E-Print Network (OSTI)

Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity fluctuations. This leads to the presence of the so-called residual energy E_r=E_v-E_b in the inertial interval of turbulence. This puzzling effect is addressed in the present paper in the framework of weak turbulence theory. Using a simple model of weakly colliding Alfv\\'en waves, we demonstrate that the kinetic-magnetic equipartition indeed gets broken as a result of nonlinear interaction of Alfv\\'en waves. We establish that magnetic energy is indeed generated more efficiently as a result of these interactions, which proposes an explanation for the solar wind observations.

Stanislav Boldyrev; Jean Carlos Perez; Vladimir Zhdankin

2011-08-30T23:59:59.000Z

164

Characteristics of Langmuir Turbulence in the Ocean Mixed Layer  

Science Conference Proceedings (OSTI)

This study uses large-eddy simulation (LES) to investigate the characteristics of Langmuir turbulence through the turbulent kinetic energy (TKE) budget. Based on an analysis of the TKE budget a velocity scale for Langmuir turbulence is proposed. ...

Alan L. M. Grant; Stephen E. Belcher

2009-08-01T23:59:59.000Z

165

Finescale Parameterizations of Turbulent Dissipation  

Science Conference Proceedings (OSTI)

Fine- and microstructure data from a free fall profiler are analysed to test models that relate the turbulent dissipation rate (?) to characteristics of the internal wave field. The data were obtained from several distinct internal wave ...

Kurt L. Polzin; John M. Toole; Raymond W. Schmitt

1995-03-01T23:59:59.000Z

166

Effect of Turbulence Models and Spatial Resolution on Resolved Velocity Structure and Momentum Fluxes in Large-Eddy Simulations of Neutral Boundary Layer Flow  

Science Conference Proceedings (OSTI)

This paper demonstrates the importance of high-quality subfilter-scale turbulence models in large-eddy simulations by evaluating the resolved-scale flow features that result from various closure models. The Advanced Regional Prediction System (...

Francis L. Ludwig; Fotini Katopodes Chow; Robert L. Street

2009-06-01T23:59:59.000Z

167

The Modification of Bottom Boundary Layer Turbulence and Mixing by Internal Waves Shoaling on a Barrier Reef  

Science Conference Proceedings (OSTI)

Results are presented from an observational study of stratified, turbulent flow in the bottom boundary layer on the outer southeast Florida shelf. Measurements of momentum and heat fluxes were made using an array of acoustic Doppler velocimeters ...

Kristen A. Davis; Stephen G. Monismith

2011-11-01T23:59:59.000Z

168

Turbulence driven particle transport in Texas Helimak  

E-Print Network (OSTI)

We analyze the turbulence driven particle transport in Texas Helimak (K. W. Gentle and Huang He, Plasma Sci. and Technology, 10, 284 (2008)), a toroidal plasma device with one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. For negative biased plasma discharges, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias the plasma has a reversed shear flow and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.

Toufen, Dennis L; Caldas, Iberę L; Marcus, Francisco A; Gentle, Kenneth W

2011-01-01T23:59:59.000Z

169

Turbulence driven particle transport in Texas Helimak  

SciTech Connect

We analyze the turbulence driven particle transport in Texas Helimak [K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)], a toroidal plasma device with a one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change the spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. When applying a negative bias, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias values, the plasma has a reversed shear flow, and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.

Toufen, D. L. [Institute of Physics, University of Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, Sao Paulo (Brazil); Federal Institute of Education, Science and Technology of Sao Paulo--IFSP, 07115-000 Guarulhos, Sao Paulo (Brazil); Guimaraes-Filho, Z. O.; Marcus, F. A. [Aix-Marseille Univ., International Institute for Fusion Science, CNRS-PIIM UMR 7345, Marseille (France); Caldas, I. L. [Institute of Physics, University of Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, Sao Paulo (Brazil); Gentle, K. W. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2012-01-15T23:59:59.000Z

170

5-ft Wave Flume Facility | Open Energy Information  

Open Energy Info (EERE)

5-ft Wave Flume Facility 5-ft Wave Flume Facility Overseeing Organization United States Army Corp of Engineers (ERDC) Hydrodynamic Testing Facility Type Flume Length(m) 63.4 Beam(m) 1.5 Depth(m) 1.5 Water Type Freshwater Cost(per day) Contact POC Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.5 Maximum Wave Height(m) at Wave Period(s) 10.0 Wave Period Range(s) 10.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Simulated Beach No Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Recirculating No Wind Capabilities Wind Capabilities None Control and Data Acquisition Description Automated data acquisition and control system Cameras None Available Sensors Flow, Pressure Range(psi), Turbulence, Velocity, Wave Probe

171

3-ft Wave Flume Facility | Open Energy Information  

Open Energy Info (EERE)

3-ft Wave Flume Facility 3-ft Wave Flume Facility Overseeing Organization United States Army Corp of Engineers (ERDC) Hydrodynamic Testing Facility Type Flume Length(m) 45.1 Beam(m) 0.9 Depth(m) 0.9 Water Type Freshwater Cost(per day) Contact POC Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.2 Maximum Wave Height(m) at Wave Period(s) 10.0 Wave Period Range(s) 10.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Simulated Beach No Channel/Tunnel/Flume Channel/Tunnel/Flume None Wind Capabilities Wind Capabilities None Control and Data Acquisition Description Automated data acquisition and control system Cameras None Available Sensors Flow, Pressure Range(psi), Turbulence, Velocity, Wave Probe

172

Helical Turbulence Prevails over Inertial Waves in Forced Rotating Flows at High Reynolds and Low Rossby Numbers  

Science Conference Proceedings (OSTI)

A study of spectral laws for helical turbulence in the presence of solid body rotation up to Reynolds numbers Re ~ 1 × 105 and down to Rossby numbers Ro ~ 3 × 10?3 is presented. The forcing function is a fully helical flow that can also be viewed ...

Julien Baerenzung; D. Rosenberg; P. D. Mininni; A. Pouquet

2011-11-01T23:59:59.000Z

173

Dust Motions Driven by MHD Turbulence  

E-Print Network (OSTI)

We discuss the relative grain motions due to MHD turbulence in interstellar medium. It has been known for decades that turbulent drag is an efficient way to induce grain relative motions. However, earlier treatments disregarded magnetic field and used Kolmogorov turbulence. Unlike hydro turbulence, MHD turbulence is anisotropic on small scales. Moreover, compressible modes are important for MHD and magnetic perturbations can directly interact with grains. We provide calculations of grain relative motion for realistic interstellar turbulence driving that is consistent with the velocity dispersions observed in diffuse gas and for realistic grain charging. We account for the turbulence cutoff arising from abmipolar drag. Our results on grain shattering are consistent with the customary accepted cutoff size. We obtain grain velocities for turbulence with parameters consistent with those in HI and dark clouds. These velocities are smaller than those in earlier papers, where MHD effects were disregarded. Finally, w...

Lazarian, A; Yan, Huirong

2002-01-01T23:59:59.000Z

174

Physical Processes of Interstellar Turbulence  

E-Print Network (OSTI)

I discuss the role of self-gravity and radiative heating and cooling in shaping the nature of the turbulence in the interstellar medium (ISM) of our galaxy. The heating and cooling cause it to be highly compressible, and, in some regimes of density and temperature, to become thermally unstable, tending to spontaneously segregate into warm/diffuse and cold/dense phases. On the other hand, turbulence is an inherently mixing process, tending to replenish the density and temperature ranges that would be forbidden under thermal processes alone. The turbulence in the ionized ISM appears to be transonic (i.e, with Mach numbers $\\Ms \\sim 1$), and thus to behave essentially incompressibly. However, in the neutral medium, thermal instability causes the sound speed of the gas to fluctuate by up to factors of $\\sim 30$, and thus the flow can be highly supersonic with respect to the dense/cold gas, although numerical simulations suggest that this behavior corresponds more to the ensemble of cold clumps than to the clumps' internal velocity dispersion. Finally, coherent large-scale compressions in the warm neutral medium (induced by, say, the passage of spiral arms or by supernova shock waves) can produce large, dense molecular clouds that are subject to their own self-gravity, and begin to contract gravitationally. Because they are populated by nonlinear density fluctuations, whose local free-fall times are significantly smaller than that of the whole cloud, the fluctuations terminate their collapse earlier, giving rise to a regime of hierarchical gravitational fragmentation, with small-scale collapses occurring within larger-scale ones. Thus, the "turbulence" in molecular clouds may be dominated by a gravitationally contracting component at all scales.

Enrique Vazquez-Semadeni

2012-02-20T23:59:59.000Z

175

Turbulent burning rates of methane and methane-hydrogen mixtures  

Science Conference Proceedings (OSTI)

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

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

2009-04-15T23:59:59.000Z

176

Lee Wave Vertical Structure Monitoring Using Height–Time Analysis of VHF?ST Radar Vertical Velocity Data  

Science Conference Proceedings (OSTI)

The strong lee wave event of intensive observation period 3 (14–15 October 1990) of the Pyrenean experiment was studied using a single VHF stratospheric–tropospheric radar installed 35 km downstream from the Pyrenean chain axis. This instrument ...

Jean-Luc Caccia

1998-05-01T23:59:59.000Z

177

Near-Inertial Waves on the New England Shelf: The Role of Evolving Stratification, Turbulent Dissipation, and Bottom Drag  

Science Conference Proceedings (OSTI)

Energetic variable near-inertial internal waves were observed on the springtime New England shelf as part of the Coastal Mixing and Optics (CMO) project. Surface warming and freshwater advection tripled the average stratification during a 3-week ...

J. A. MacKinnon; M. C. Gregg

2005-12-01T23:59:59.000Z

178

Estimating Spatial Velocity Statistics with Coherent Doppler Lidar  

Science Conference Proceedings (OSTI)

The spatial statistics of a simulated turbulent velocity field are estimated using radial velocity estimates from simulated coherent Doppler lidar data. The structure functions from the radial velocity estimates are processed to estimate the ...

Rod Frehlich; Larry Cornman

2002-03-01T23:59:59.000Z

179

ARM - Measurement - Atmospheric turbulence  

NLE Websites -- All DOE Office Websites (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

180

Plasma wave propagation with a plasma density gradient  

Science Conference Proceedings (OSTI)

Plasma waves with the plasma diffusion velocity u{sub n} due to a plasma density gradient are described in a positive column plasma. The ion wave is generated by the perturbation of the operating frequency 10{sup 6} s{sup -1} and it propagates with the group velocity u{sub g{approx}}c{sub s}{sup 2}/u{sub n{approx}}(10{sup 5}-10{sup 6}) m/s, where c{sub s} is the acoustic velocity in a fine tube fluorescent lamp, while the electron wave cannot be generated with a turbulence of low frequency less than the electron oscillation frequency {omega}{sub pe}. The propagation of the lighting signal observed in long tube fluorescent lamps is well understood with the propagation of ion waves occurring along the plasma density gradient.

Cho, Guangsup; Choi, Eun-Ha; Uhm, Han Sup [Department of Electrophysics, Kwangwoon University, 447-1 Nowon Wallgye, Seoul 139-701 (Korea, Republic of)

2011-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Dust Motions Driven by MHD Turbulence  

E-Print Network (OSTI)

We discuss the relative grain motions due to MHD turbulence in interstellar medium. It has been known for decades that turbulent drag is an efficient way to induce grain relative motions. However, earlier treatments disregarded magnetic field and used Kolmogorov turbulence. Unlike hydro turbulence, MHD turbulence is anisotropic on small scales. Moreover, compressible modes are important for MHD and magnetic perturbations can directly interact with grains. We provide calculations of grain relative motion for realistic interstellar turbulence driving that is consistent with the velocity dispersions observed in diffuse gas and for realistic grain charging. We account for the turbulence cutoff arising from abmipolar drag. Our results on grain shattering are consistent with the customary accepted cutoff size. We obtain grain velocities for turbulence with parameters consistent with those in HI and dark clouds. These velocities are smaller than those in earlier papers, where MHD effects were disregarded. Finally, we consider grain velocities arising from photoelectric emission, radiation pressure and the thrust due to molecular hydrogen formation. These are lower than relative velocities induced by turbulence. We conclude that turbulence should prevent these mechanisms from segregating grains by size.

A. Lazarian; Huirong Yan

2002-05-17T23:59:59.000Z

182

High-Frequency Internal Waves at 0°, 140°W and Their Possible Relationship to Deep-Cycle Turbulence  

Science Conference Proceedings (OSTI)

An analysis of a moored time series at 0°, 140°W from November to December 1991 found a nighttime enhancement of isotherm displacement variance and of zonal velocity variance below the surface mixed layer at frequencies higher than 1 cph. The ...

Ren-Chieh Lien; Michael J. McPhaden; Michael C. Gregg

1996-04-01T23:59:59.000Z

183

The Atmospheric Boundary Layer during Swell: A Field Study and Interpretation of the Turbulent Kinetic Energy Budget for High Wave Ages  

Science Conference Proceedings (OSTI)

Analysis of the turbulent kinetic energy (TKE) budget for five slightly unstable cases with swell has been performed based on measurements of mechanical production, buoyancy production, turbulent transport, and dissipation at five levels over the ...

U. Högström; A. Smedman; E. Sahleé; W. M. Drennan; K. K. Kahma; H. Pettersson; F. Zhang

2009-09-01T23:59:59.000Z

184

In-plane ultrasonic velocity measurement of longitudinal and shear waves in the machine direction with transducers in rotating wheels  

DOE Patents (OSTI)

An improved system for measuring the velocity of ultrasonic signals within the plane of moving web-like materials, such as paper, paperboard and the like. In addition to velocity measurements of ultrasonic signals in the plane of the web in the MD and CD, one embodiment of the system in accordance with the present invention is also adapted to provide on-line indication of the polar specific stiffness of the moving web. In another embodiment of the invention, the velocity of ultrasonic signals in the plane of the web are measured by way of a plurality of ultrasonic transducers carried by synchronously driven wheels or cylinders, thus eliminating undue transducer wear due to any speed differences between the transducers and the web. In order to provide relatively constant contact force between the transducers and the webs, the transducers are mounted in a sensor housings which include a spring for biasing the transducer radially outwardly. The sensor housings are adapted to be easily and conveniently mounted to the carrier to provide a relatively constant contact force between the transducers and the moving web.

Hall, Maclin S. (Marietta, GA); Jackson, Theodore G. (Atlanta, GA); Knerr, Christopher (Lawrenceville, GA)

1998-02-17T23:59:59.000Z

185

In-plane ultrasonic velocity measurement of longitudinal and shear waves in the machine direction with transducers in rotating wheels  

DOE Patents (OSTI)

An improved system for measuring the velocity of ultrasonic signals within the plane of moving web-like materials, such as paper, paperboard and the like. In addition to velocity measurements of ultrasonic signals in the plane of the web in the MD and CD, one embodiment of the system in accordance with the present invention is also adapted to provide on-line indication of the polar specific stiffness of the moving web. In another embodiment of the invention, the velocity of ultrasonic signals in the plane of the web are measured by way of a plurality of ultrasonic transducers carried by synchronously driven wheels or cylinders, thus eliminating undue transducer wear due to any speed differences between the transducers and the web. In order to provide relatively constant contact force between the transducers and the webs, the transducers are mounted in a sensor housings which include a spring for biasing the transducer radially outwardly. The sensor housings are adapted to be easily and conveniently mounted to the carrier to provide a relatively constant contact force between the transducers and the moving web. 37 figs.

Hall, M.S.; Jackson, T.G.; Knerr, C.

1998-02-17T23:59:59.000Z

186

Lattice Boltzmann equation simulations of turbulence, mixing, and combustion  

E-Print Network (OSTI)

We explore the capability of lattice Boltzmann equation (LBE) method for complex fluid flows involving turbulence, mixing, and reaction. In the first study, LBE schemes for binary scalar mixing and multi-component reacting flow with reactions are developed. Simulations of initially non-premixed mixtures yield scalar probability distribution functions that are in good agreement with numerical data obtained from Navier-Stokes (NS) equation based computation. One-dimensional chemically-reacting flow simulation of a premixed mixture yields a flame speed that is consistent with experimentally determined value. The second study involves direct numerical simulation (DNS) and large-eddy simulation (LES) of decaying homogenous isotropic turbulence (HIT) with and without frame rotation. Three categories of simulations are performed: (i) LBE-DNS in both inertial and rotating frames; (ii) LBE-LES in inertial frame; (iii) Comparison of the LBE-LES vs. NS-LES. The LBE-DNS results of the decay exponents for kinetic energy k and dissipation rate ?, and the low wave-number scaling of the energy spectrum agree well with established classical results. The LBE-DNS also captures rotating turbulence physics. The LBE-LES accurately captures low-wave number scaling, energy decay and large scale structures. The comparisons indicate that the LBE-LES simulations preserve flow structures somewhat more accurately than the NS-LES counterpart. In the third study, we numerically investigate the near-field mixing features in low aspect-ratio (AR) rectangular turbulent jets (RTJ) using the LBE method. We use D3Q19 multiple-relaxation-time (MRT) LBE incorporating a subgrid Smagorinsky model for LES. Simulations of four jets which characterized by AR, exit velocity, and Reynolds number are performed. The investigated near-field behaviors include: (1) Decay of mean streamwise velocity (MSV) and inverse MSV; (2) Spanwise and lateral profiles of MSV; (3) Half-velocity width development and MSV contours; and (4) Streamwise turbulence intensity distribution and spanwise profiles of streamwise turbulence intensity. The computations are compared against experimental data and the agreement is good. We capture both unique features of RTJ: the saddle-back spanwise profile of MSV and axis-switching of long axis from spanwise to lateral direction. Overall, this work serves to establish the feasibility of the LBE method as a viable tool for computing mixing, combustion, and turbulence.

Yu, Huidan

2004-12-01T23:59:59.000Z

187

Dust ion-acoustic shock waves in charge varying dusty plasmas with electrons having vortexlike velocity distribution  

Science Conference Proceedings (OSTI)

A weakly nonlinear analysis is carried out to investigate the properties of dust ion-acoustic shock waves in a charge varying dusty plasma with vortexlike electron distribution. We use the ionization model, hot ions with equilibrium streaming speed and a trapped electron charging current derived from the well-known orbit limited motion theory. A new modified Burger equation is derived. Besides nonlinear trapping, this equation involves two kinds of dissipation (the anomalous one inherent to nonadiabatic dust charge fluctuation and the one due to the particle loss and ionization). These two kinds of dissipation can act concurrently. The traveling wave solution has been acquired by employing the modified extended tanh-function method. The shocklike solution is numerically analyzed based on the typical numerical data from laboratory dusty plasma devices. It is found that ion temperature, trapped particles, and weak dissipations significantly modify the shock structures.

Alinejad, H. [Department of Physics, Faculty of Basic Science, Babol University of Technology, Babol 47148-71167 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, P.O. Box 55134-441, Maragha 55177-36698 (Iran, Islamic Republic of); Tribeche, M. [Plasma Physics Group (PPG), Theoretical Physics Laboratory (TPL), Faculty of Science-Physics, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers (Algeria)

2010-12-15T23:59:59.000Z

188

Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence Spectrum  

E-Print Network (OSTI)

With the diffusion approximation, we study the cascade and damping of Alfv\\'{e}n-cyclotron fluctuations in solar plasmas numerically. Motivated by wave-wave couplings and nonlinear effects, we test several forms of the diffusion tensor. For a general locally anisotropic and inhomogeneous diffusion tensor in the wave vector space, the turbulence spectrum in the inertial range can be fitted with power-laws with the power-law index varying with the wave propagation direction. For several locally isotropic but inhomogeneous diffusion coefficients, the steady-state turbulence spectra are nearly isotropic in the absence of damping and can be fitted by a single power-law function. However, the energy flux is strongly polarized due to the inhomogeneity that leads to an anisotropic cascade. Including the anisotropic thermal damping, the turbulence spectrum cuts off at the wave numbers, where the damping rates become comparable to the cascade rates. The combined anisotropic effects of cascade and damping make this cutoff wave number dependent on the wave propagation direction, and the propagation direction integrated turbulence spectrum resembles a broken power-law, which cuts off at the maximum of the cutoff wave numbers or the $^4$He cyclotron frequency. Taking into account the Doppler effects, the model can naturally reproduce the broken power-law wave spectra observed in the solar wind and predicts that a higher break frequency is aways accompanied with a greater spectral index change that may be caused by the increase of the Alfv\\'{e}n Mach number, the reciprocal of the plasma beta, and/or the angle between the solar wind velocity and the mean magnetic field. These predictions can be tested by future observations.

Yan Wei Jiang; Siming Liu; Vahé Petrosian; Christopher L. Fryer

2008-02-07T23:59:59.000Z

189

Observations of Turbulence within a Natural Surf Zone  

Science Conference Proceedings (OSTI)

Here, the Reynolds stresses u?w? and ??w?, where u?, ??, and w? are the cross-shore, alongshore, and vertical turbulence velocities, respectively, and the angle brackets represent time averaging, are used to diagnose turbulence dynamics ...

B. G. Ruessink

2010-12-01T23:59:59.000Z

190

Modeling Optical Turbulence and Seeing over Mauna Kea  

Science Conference Proceedings (OSTI)

Atmospheric turbulence is a primary concern for astronomers. Turbulence causes amplitude and phase fluctuations in electromagnetic waves propagating through the atmosphere, constraining the maximum telescope resolution and resulting in telescope ...

T. Cherubini; S. Businger; R. Lyman; M. Chun

2008-04-01T23:59:59.000Z

191

Measurement and theory of turbulence in RR Lyrae  

SciTech Connect

CORAVEL observations of time-dependent turbulence in RR Lyrae are presented. Variation in the width of the mean velocity correlation function implies turbulent velocities that peak at 10 to 15 km/sec for a brief interval of phase near minimum radius. Comparison with a nonlinear pulsation model shows that these amplitudes of the turbulent velocity are expected near the hydrogen ionization zone, again only near minimum radius.

Benz, W.; Stellingwerf, R.F.

1985-01-01T23:59:59.000Z

192

Shear-current effect in a turbulent convection with a large-scale shear  

E-Print Network (OSTI)

The shear-current effect in a nonrotating homogeneous turbulent convection with a large-scale constant shear is studied. The large-scale velocity shear causes anisotropy of turbulent convection, which produces the mean electromotive force $\\bec{\\cal E}^{(W)} \\propto {\\bf W} {\\bf \\times} {\\bf J}$ and the mean electric current along the original mean magnetic field, where ${\\bf W}$ is the background mean vorticity due to the shear and ${\\bf J}$ is the mean electric current. This results in a large-scale dynamo even in a nonrotating and nonhelical homogeneous sheared turbulent convection, whereby the $\\alpha$ effect vanishes. It is found that turbulent convection promotes the shear-current dynamo instability, i.e., the heat flux causes positive contribution to the shear-current effect. However, there is no dynamo action due to the shear-current effect for small hydrodynamic and magnetic Reynolds numbers even in a turbulent convection, if the spatial scaling for the turbulent correlation time is $\\tau(k) \\propto k^{-2}$, where $k$ is the small-scale wave number.

I. Rogachevskii; N. Kleeorin

2007-02-24T23:59:59.000Z

193

Radar Wind Profiler Radial Velocity: A Comparison with Doppler Lidar  

Science Conference Proceedings (OSTI)

The accuracy of the radial wind velocity measured with a radar wind profiler will depend on turbulent variability and instrumental noise. Radial velocity estimates of a boundary layer wind profiler are compared with those estimated by a Doppler ...

Stephen A. Cohn; R. Kent Goodrich

2002-12-01T23:59:59.000Z

194

Electromagnetic weak turbulence theory revisited  

SciTech Connect

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

195

Nonlinear shear-current dynamo and magnetic helicity transport in sheared turbulence  

E-Print Network (OSTI)

The nonlinear mean-field dynamo due to a shear-current effect in a nonhelical homogeneous turbulence with a mean velocity shear is discussed. The transport of magnetic helicity as a dynamical nonlinearity is taken into account. The shear-current effect is associated with the ${\\bf W} {\\bf \\times} {\\bf J}$ term in the mean electromotive force, where ${\\bf W}$ is the mean vorticity due to the large-scale shear motions and ${\\bf J}$ is the mean electric current. This effect causes the generation of large-scale magnetic field in a turbulence with large hydrodynamic and magnetic Reynolds numbers. The dynamo action due to the shear-current effect depends on the spatial scaling of the correlation time $\\tau(k)$ of the background turbulence, where $k$ is the wave number. For Kolmogorov scaling, $\\tau(k) \\propto k^{-2/3}$, the dynamo instability occurs, while when $\\tau(k) \\propto k^{-2}$ (small hydrodynamic and magnetic Reynolds numbers) there is no the dynamo action in a sheared nonhelical turbulence. The magnetic helicity flux strongly affects the magnetic field dynamics in the nonlinear stage of the dynamo action. Numerical solutions of the nonlinear mean-field dynamo equations which take into account the shear-current effect, show that if the magnetic helicity flux is not small, the saturated level of the mean magnetic field is of the order of the equipartition field determined by the turbulent kinetic energy. Turbulence with a large-scale velocity shear is a universal feature in astrophysics, and the obtained results can be important for elucidation of origin of the large-scale magnetic fields in astrophysical sheared turbulence.

I. Rogachevskii; N. Kleeorin; E. Liverts

2006-09-10T23:59:59.000Z

196

Vertical stratified turbulent transport mechanism indicated by remote sensing  

E-Print Network (OSTI)

Satellite and shipboard data reveal the intermittent vertical information transport mechanism of turbulence and internal waves that mixes the ocean, atmosphere, planets and stars.

Gibson, Carl H; Bondur, Valery G

2007-01-01T23:59:59.000Z

197

Vertical stratified turbulent transport mechanism indicated by remote sensing  

E-Print Network (OSTI)

Satellite and shipboard data reveal the intermittent vertical information transport mechanism of turbulence and internal waves that mixes the ocean, atmosphere, planets and stars.

Carl H. Gibson; R. Norris Keeler; Valery G. Bondur

2007-12-02T23:59:59.000Z

198

Dispersion of Heavy Particles by Turbulent Motion  

Science Conference Proceedings (OSTI)

Accurate prediction of heavy particle dispersion in turbulent flows requires a simultaneous consideration of particle's inertia and particle's drift velocity. A mathematically simple and physically comprehensive analysis was developed to solve ...

Lian-Ping Wang; Davd E. Stock

1993-07-01T23:59:59.000Z

199

Advances in compressible turbulent mixing  

Science Conference Proceedings (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

200

Extreme wave impinging and overtopping  

E-Print Network (OSTI)

This investigates the velocity fields of a plunging breaking wave impinging on a structure through measurements in a two-dimensional wave tank. As the wave breaks and overtops the structure, so-called green water is generated. The flow becomes multi-phased and chaotic as a highly aerated region is formed in the flow in the vicinity of the structure while water runs up onto the structure. In this study, particle image velocimetry (PIV) was employed to measure the velocity field of the water dominant region. For measurements of an aerated region that cannot be measured by PIV, a new measurement method called bubble image velocimetry (BIV) was developed. The principle and setup of the BIV method were introduced and validated. Mean and turbulence properties were obtained through ensemble averaging repeated tests measured by both methods. The dominant and maximum velocity of the breaking wave and associated green water are discussed for the three distinct phases of the impingement-runup-overtopping sequence. The distribution of the green water velocity along the top of the structure has a nonlinear profile and the maximum velocity occurs near the front of the fast moving water. Using the measured data and applying dimensional analysis, a similarity profile for the green water flow on top of the structure was obtained, and a prediction equation was formulated. The dam breaking solution used for the green water prediction was examined with determining initial water depth based on the experiment conditions. Comparison between measurements, the prediction equation, and the dam breaking flow was made. The prediction equation and the dam break flow with appropriate initial water depth may be used to predict the green water velocity caused by extreme waves in a hurricane. To demonstrate the aeration of the breaking wave and overtopping water, void fraction was also investigated. There is strong aeration in the region of overtopping water front generated by a plunging breaker. Void fraction of overtopping water was measured using a fiber optic reflectometer (FOR). The measured velocity and void fraction were also used to estimate flow rate and water volume of overtopping water.

Ryu, Yong Uk

2006-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Estimating Oceanic Turbulence Dissipation from Seismic Images  

Science Conference Proceedings (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

202

Lagrangian formulation of turbulent premixed combustion  

E-Print Network (OSTI)

The Lagrangian point of view is adopted to study turbulent premixed combustion. The evolution of the volume fraction of combustion products is established by the Reynolds transport theorem. It emerges that the burned-mass fraction is led by the turbulent particle motion, by the flame front velocity, and by the mean curvature of the flame front. A physical requirement connecting particle turbulent dispersion and flame front velocity is obtained from equating the expansion rates of the flame front progression and of the unburned particles spread. The resulting description compares favorably with experimental data. In the case of a zero-curvature flame, with a non-Markovian parabolic model for turbulent dispersion, the formulation yields the Zimont equation extended to all elapsed times and fully determined by turbulence characteristics. The exact solution of the extended Zimont equation is calculated and analyzed to bring out different regimes.

Pagnini, Gianni

2011-01-01T23:59:59.000Z

203

Dynamics of Wave Breaking at a Coastal Sea Wall  

E-Print Network (OSTI)

Structural designs barely consider the dynamic scenario of a well-developed impinging wave hitting the structure. The usual area of focus is on static and stability factors (e.g. drag, inertia, resistive forces related to weight, buoyancy, sliding etc). Even the "Factor of Safety" which is regularly used in designs to account for unknown and/or unforeseen situations which might occur implies a degree of uncertainty about the dynamic scenario of breaking waves in the coastal environment. In the present study the hydrodynamics of a coastal structure-turbulent bore interaction was studied by examination (two-dimensional) of the singular case of a plunging breaking wave forming a well developed turbulent bore which impacted on a model sea wall structure. The turbulent bore impact event was found to display similar characteristics to the impact event of other wave shapes, in particular that of a plunging breaker. Examination of the impact event confirmed the conversion of nearly all horizontal velocity to vertical velocity during the "flip through" event. In accordance with theoretical expectations the location of maximum pressure was found to occur just below the still water level (SWL). Resulting pressure data in the present study consisted of two blunt spikes as opposed to the "church-roof" (high spike) shape seen in other results. The shape of the pressure data was attributed to the following: firstly, to the initial impact of the protruding jet of the breaking wave which causes the first maxima, secondly, to the sensor encountering the bulk of the entrapped air hence causing the drop in pressure between the blunt spikes and lastly, to the inherent hydrostatic pressure combined with the compression of the entrapped air bubbles, by the subsequent forward motion of the water within the wave, which causes the second maxima. The point of maximum pressure was found to always be within the second maxima. Observation of the turbulent bore-structure interaction showed that the consequential maximum pressure was a direct result of the compression of entrapped air by the weight of the water in the wave as it continued forward onto the structure combined with the inherent hydrostatic pressure of the wave. The project was conducted in an attempt to contribute to the vast knowledge of coastal structure-wave interactions and to add to the understanding of the physics and characteristics of breaking waves. Whilst numerous studies and experiments have been carried out on the phenomenon of breaking waves by previous researchers the current project highlights the advent of new equipment and technological advances in existing methods.

Antoine, Arthur L.

2009-12-01T23:59:59.000Z

204

Gravitational radiation from primordial helical inverse cascade magnetohydrodynamic turbulence  

SciTech Connect

We consider the generation of gravitational waves by primordial helical inverse-cascade magnetohydrodynamic (MHD) turbulence produced by bubble collisions at the electroweak phase transition. We extend the previous study 1 by considering both currently discussed models of MHD turbulence. For popular electroweak phase transition parameter values, the generated gravitational wave spectrum is only weakly dependent on the MHD turbulence model. Compared with the unmagnetized electroweak phase transition case, the spectrum of MHD-turbulence-generated gravitational waves peaks at lower frequency with larger amplitude and can be detected by the proposed Laser Interferometer Space Antenna.

Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Campanelli, Leonardo [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); INFN - Sezione di Bari, I-70126 Bari (Italy); Gogoberidze, Grigol [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); National Astrophysical Observatory, Ilia Chavchavadze State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Maravin, Yurii; Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2008-12-15T23:59:59.000Z

205

Spectrum of gravitational radiation from primordial turbulence  

Science Conference Proceedings (OSTI)

Energy injection into the early universe can induce turbulent motions of the primordial plasma, which in turn act as a source for gravitational radiation. Earlier work computed the amplitude and characteristic frequency of the relic gravitational wave background, as a function of the total energy injected and the stirring scale of the turbulence. This paper computes the frequency spectrum of relic gravitational radiation from a turbulent source of the stationary Kolmogoroff form which acts for a given duration, making no other approximations. We also show that the limit of long source wavelengths, commonly employed in aeroacoustic problems, is an excellent approximation. The gravitational waves from cosmological turbulence around the electroweak energy scale will be detectable by future space-based laser interferometers for a substantial range of turbulence parameters.

Gogoberidze, Grigol [Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, GE-0160 Tbilisi (Georgia); Kahniashvili, Tina [Center for Cosmology and Particle Physics, New York University, 4 Washington Plaza, New York, New York 10003 (United States); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, GE-0160 Tbilisi (Georgia); Kosowsky, Arthur [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, Pennsylvania 15260 (United States)

2007-10-15T23:59:59.000Z

206

A Surface Flux Parameterization Based on the Vertically Averaged Turbulence Kinetic Energy  

Science Conference Proceedings (OSTI)

A new bulk transfer formulation for the surface turbulent fluxes of momentum, heat, and moisture has been developed by using the square root of the vertically averaged turbulent kinetic energy (TKE) in the atmospheric boundary layer as a velocity ...

Changan Zhang; David A. Randall; Chin-Hoh Moeng; Mark Branson; Kerry A. Moyer; Qing Wang

1996-11-01T23:59:59.000Z

207

Turbulence Dynamics at the Shoal–Channel Interface in a Partially Stratified Estuary  

Science Conference Proceedings (OSTI)

Turbulence observations at the shoal–channel interface in South San Francisco Bay are described and analyzed in this work. Profiles of turbulent kinetic energy (TKE) shear production and dissipation rate are estimated from ADCP beam velocities ...

Audric G. Collignon; Mark T. Stacey

2013-05-01T23:59:59.000Z

208

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

Science Conference Proceedings (OSTI)

Coherent jets, such as the Jovian banded winds, are a prominent feature of rotating turbulence. Shallow-water turbulence models capture the essential mechanism of jet formation, which is systematic eddy momentum flux directed up the mean velocity ...

Brian F. Farrell; Petros J. Ioannou

2009-10-01T23:59:59.000Z

209

The Quest for K?—Preliminary Results from Direct Measurements of Turbulent Fluxes in the Ocean  

Science Conference Proceedings (OSTI)

Simultaneous measurements of vertical velocity fluctuations, w?, and temperature fluctuations, T?, on scales of three-dimensional turbulence yield a direct measure of the turbulent heat flux, Jq. The scales contributing most significantly to Jq ...

J. N. Moum

1990-12-01T23:59:59.000Z

210

Stress on the Mediterranean Outflow Plume: Part II. Turbulent Dissipation and Shear Measurements  

Science Conference Proceedings (OSTI)

Bottom and interfacial stresses on the Mediterranean outflow plume are estimated using vertical profiles of turbulent dissipation and velocity collected in the Gulf of Cadiz. Turbulent dissipation is high throughout the plume, with a local ...

Gregory C. Johnson; Rolf G. Lueck; Thomas B. Sanford

1994-10-01T23:59:59.000Z

211

Transilient Turbulence Theory. Part II: Turbulent Adjustment  

Science Conference Proceedings (OSTI)

Turbulent adjustment is a scheme where dynamic instabilities in the flow are eliminated by turbulence. It is a form of first-order turbulence closure that is applicable to numerical forecast models of the atmosphere. The responsive form of ...

Roland B. Stull; Takehiko Hasegawa

1984-12-01T23:59:59.000Z

212

Turbulent molecular clouds  

E-Print Network (OSTI)

Stars form within molecular clouds but our understanding of this fundamental process remains hampered by the complexity of the physics that drives their evolution. We review our observational and theoretical knowledge of molecular clouds trying to confront the two approaches wherever possible. After a broad presentation of the cold interstellar medium and molecular clouds, we emphasize the dynamical processes with special focus to turbulence and its impact on cloud evolution. We then review our knowledge of the velocity, density and magnetic fields. We end by openings towards new chemistry models and the links between molecular cloud structure and star--formation rates.

Hennebelle, Patrick

2012-01-01T23:59:59.000Z

213

On the Linear Approximation of Gravity Wave Saturation in the Mesosphere  

Science Conference Proceedings (OSTI)

Lincizen's model of gravity wave breaking is shown to be inconsistent with the process of convective adjustment and associated turbulent outbreak. The K-theory turbulent diffusion model used by Lindzen implies a spatially uniform turbulent field ...

Winston C. Chao; Mark R. Schoeberl

1984-06-01T23:59:59.000Z

214

A Near-Surface Microstructure Sensor System Used during TOGA COARE. Part II: Turbulence Measurements  

Science Conference Proceedings (OSTI)

New techniques developed for near-surface turbulence measurements during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE) employ a difference in spatial scales of turbulence and surface waves. ...

A. Soloviev; R. Lukas; P. Hacker; H. Schoeberlein; M. Baker; A. Arjannikov

1999-11-01T23:59:59.000Z

215

Probability Densities in Strong Turbulence  

E-Print Network (OSTI)

According to modern developments in turbulence theory, the "dissipation" scales (u.v. cut-offs) $\\eta$ form a random field related to velocity increments $\\delta_{\\eta}u$. In this work we, using Mellin's transform combined with the Gaussain large -scale boundary condition, calculate probability densities (PDFs) of velocity increments $P(\\delta_{r}u,r)$ and the PDF of the dissipation scales $Q(\\eta, Re)$, where $Re$ is the large-scale Reynolds number. The resulting expressions strongly deviate from the Log-normal PDF $P_{L}(\\delta_{r}u,r)$ often quoted in the literature. It is shown that the probability density of the small-scale velocity fluctuations includes information about the large (integral) scale dynamics which is responsible for deviation of $P(\\delta_{r}u,r)$ from $P_{L}(\\delta_{r}u,r)$. A framework for evaluation of the PDFs of various turbulence characteristics involving spatial derivatives is developed. The exact relation, free of spurious Logarithms recently discussed in Frisch et al (J. Fluid Mech. {\\bf 542}, 97 (2005)), for the multifractal probability density of velocity increments, not based on the steepest descent evaluation of the integrals is obtained and the calculated function $D(h)$ is close to experimental data. A novel derivation (Polyakov, 2005), of a well-known result of the multi-fractal theory [Frisch, "Turbulence. {\\it Legacy of A.N.Kolmogorov}", Cambridge University Press, 1995)), based on the concepts described in this paper, is also presented.

Victor Yakhot

2005-12-12T23:59:59.000Z

216

Simulations of 2D magnetic electron drift vortex mode turbulence in plasmas  

E-Print Network (OSTI)

Simulations are performed to investigate turbulent properties of nonlinearly interacting two-dimensional (2D) magnetic electron drift vortex (MEDV) modes in a nonuniform unmagnetized plasma. The relevant nonlinear equations governing the dynamics of the MEDV modes are the wave magnetic field and electron temperature perturbations in the presence of the equilibrium density and temperature gradients. The important nonlinearities come from the advection of the electron fluid velocity perturbation and the electron temperature, as well as from the nonlinear electron Lorentz force. Computer simulations of the governing equations for the nonlinear MEDV modes reveal the generation of streamer-like electron flows, such that the corresponding gradients in the direction of the inhomogeneities tend to flatten out. By contrast, the gradients in an orthogonal direction vary rapidly. Consequently, the inertial range energy spectrum in decaying MEDV mode turbulence exhibits a much steeper anisotropic spectral index. The magn...

Shaikh, Dastgeer

2008-01-01T23:59:59.000Z

217

The decay of multiscale signals deterministic model of the Burgers turbulence  

E-Print Network (OSTI)

This work is devoted to the study of the decay of multiscale deterministicsolutions of the unforced Burgers' equation in the limit of vanishingviscosity. A deterministic model of turbulence-like evolution is considered. We con-struct the initial perturbation as a piecewise linear analog of the Weierstrassfunction. The wavenumbers of this function form a "Weierstrass spectrum", whichaccumulates at the origin in geometric progression."Reverse" sawtooth functionswith negative initial slope are used in this series as basic functions, whiletheir amplitudes are chosen by the condition that the distribution of energyover exponential intervals of wavenumbers is the same as for the continuousspectrum in Burgers turbulence. Combining these two ideas allows us to obtainan exact analytical solution for the velocity field. We also notice that suchmultiscale waves may be constructed for multidimensional Burgers' equation. This solution has scaling exponent h=-(1+n)/2 and its evolution in time isself-similar with logarithmi...

Gurbatov, S N

2000-01-01T23:59:59.000Z

218

Diffusion Processes in Turbulent Magnetic Fields  

E-Print Network (OSTI)

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

Alex Lazarian

2007-07-04T23:59:59.000Z

219

Diffusion Processes in Turbulent Magnetic Fields  

E-Print Network (OSTI)

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

Lazarian, Alex

2007-01-01T23:59:59.000Z

220

Alfvenic Turbulence in the Extended Solar Corona: Kinetic Effects and Proton Heating  

E-Print Network (OSTI)

We present a model of magnetohydrodynamic (MHD) turbulence in the extended solar corona that contains the effects of collisionless dissipation and anisotropic particle heating. Measurements made by UVCS/SOHO have revived interest in the idea that ions are energized by the dissipation of ion cyclotron resonant waves, but such high-frequency (i.e., small wavelength) fluctuations have not been observed. A turbulent cascade is one possible way of generating small-scale fluctuations from a pre-existing population of low-frequency MHD waves. We model this cascade as a combination of advection and diffusion in wavenumber space. The dominant spectral transfer occurs in the direction perpendicular to the background magnetic field. As expected from earlier models, this leads to a highly anisotropic fluctuation spectrum with a rapidly decaying tail in parallel wavenumber. The wave power that decays to high enough frequencies to become ion cyclotron resonant depends on the relative strengths of advection and diffusion in the cascade. For the most realistic values of these parameters, though, there is insufficient power to heat protons and heavy ions. The dominant oblique fluctuations (with dispersion properties of kinetic Alfven waves) undergo Landau damping, which implies strong parallel electron heating. We discuss the probable nonlinear evolution of the electron velocity distributions into parallel beams and discrete phase-space holes (similar to those seen in the terrestrial magnetosphere) which can possibly heat protons via stochastic interactions.

S. R. Cranmer; A. A. van Ballegooijen

2003-05-08T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

The Efficiency of Second-Order Fermi Acceleration by Weakly Compressible MHD Turbulence  

E-Print Network (OSTI)

We investigate the effects of pitch-angle scattering on the efficiency of particle heating and acceleration by MHD turbulence using phenomenological estimates and simulations of non-relativistic test particles interacting with strong, subsonic MHD turbulence. We include an imposed pitch-angle scattering rate, which is meant to approximate the effects of high frequency plasma waves and/or velocity space instabilities. We focus on plasma parameters similar to those found in the near-Earth solar wind, though most of our results are more broadly applicable. An important control parameter is the size of the particle mean free path lambda_{mfp} relative to the scale of the turbulent fluctuations L. For small scattering rates, particles interact quasi-resonantly with turbulent fluctuations in magnetic field strength. Scattering increases the long-term efficiency of this resonant heating by factors of a few-10, but the distribution function does not develop a significant non-thermal power-law tail. For higher scatter...

Lynn, Jacob W; Chandran, Benjamin D G; Parrish, Ian J

2013-01-01T23:59:59.000Z

222

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

223

Profiler Measurements of Vertical Velocity Fluctuations in the Ocean  

Science Conference Proceedings (OSTI)

A method is described for measuring the vertical component of velocity fluctuations due to three-dimensional turbulence in the ocean from a freely falling microstructure profiler. The dynamic pressure measurement relies on a commercially ...

J. N. Moum

1990-04-01T23:59:59.000Z

224

Resonantly Forced Rossby Waves  

Science Conference Proceedings (OSTI)

A shallow, rotating layer of fluid that supports Rossby waves is subjected to turbulent friction through an Ekman layer at the bottom and is driven by a wave that exerts a shear stress on the upper boundary and for which the phase approximate ...

John Miles

1985-04-01T23:59:59.000Z

225

Effects of Wind Turbulence on Coherent Doppler Lidar Performance  

Science Conference Proceedings (OSTI)

The effects of wind turbulence on pulsed coherent Doppler lidar performance are investigated theoretically and with computer simulations. The performance of velocity estimators is determined for the case of a single realization of a wind field ...

Rod Frehlich

1997-02-01T23:59:59.000Z

226

Energy Dissipation Rates of Turbulence in the Stable Free Atmosphere  

Science Conference Proceedings (OSTI)

For stable stratification, it is pointed out that there exists a strong correlation between the intensity of atmospheric turbulence and the energy dissipation rate ?. It is given in terms of the variance of vertical velocity ?w2 and the Brunt-...

J. Weinstock

1981-04-01T23:59:59.000Z

227

Estimates of Turbulence from Numerical Weather Prediction Model Output with Applications to Turbulence Diagnosis and Data Assimilation  

Science Conference Proceedings (OSTI)

Estimates of small-scale turbulence from numerical model output are produced from local estimates of the spatial structure functions of model variables such as the velocity and temperature. The key assumptions used are the existence of a ...

Rod Frehlich; Robert Sharman

2004-10-01T23:59:59.000Z

228

Compressible Shear Flow Transition and Turbulence: Enhancement of GKM Numerical Scheme and Simulation/Analysis of Pressure Effects on Flow Stabilization  

E-Print Network (OSTI)

Despite significant advancements in the understanding of fluid flows, combustion and material technologies, hypersonic flight still presents numerous technological challenges. In hypersonic vehicles turbulence is critical in controlling heat generation in the boundary layer, mixing inside the combustor, generation of acoustic noise, and mass flow in the intake. The study of turbulence in highly compressible flows is challenging compared to incompressible due to a drastic change in the behavior of pressure and a relaxation of the incompressibility constraint. In addition fluid flow inside a flight vehicle is complicated by wall-effects, heat generation and complex boundary conditions. Homogeneous shear flow contains most of the relevant physics of boundary and mixing layers without the aforementioned complicating effects. In this work we aim to understand and characterize the role of pressure, velocity-pressure interaction, velocity-thermodynamics interaction in the late-stage transition-to-turbulence regime in a high speed shear dominated flow by studying the evolution of perturbations in in a high Mach number homogeneous shear flow. We use a modal-analysis based approach towards understanding the statistical behavior of turbulence. Individual Fourier waves constituting the initial flow field are studied in isolation and in combination to understand collective statistical behavior. We demonstrate proof of concept of novel acoustic based strategies for controlling the onset of turbulence. Towards this goal we perform direct numerical simulations (DNS) in three studies: (a) development and evaluation of gas kinetic based numerical tool for DNS of compressible turbulence, and perform detailed evaluation of the efficacy of different interpolation schemes in capturing solenoidal and dilatational quantities, (b) modal investigation in the behavior of pressure and isolation of linear, non-linear, inertial and pressure actions, and (c) modal investigation in the possible acoustic based control strategies in homogeneously sheared compressible flows. The findings help to understand the manifestation of the effects of compressibility on transition and turbulence via the velocity-pressure interactions and the action of individual waves. The present study helps towards the design of control mechanisms for compressible turbulence and the development of physically consistent pressure strain correlation models.

Kumar, Gaurav 1984-

2012-12-01T23:59:59.000Z

229

Weak and strong regimes of incompressible magnetohydrodynamic turbulence  

Science Conference Proceedings (OSTI)

It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade time scales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence that implies a large number of collisions among wave packets for an efficient energy cascade (such as the Iroshnikov-Kraichnan model) is not compatible with the weak turbulence theory.

Gogoberidze, G. [Centre for Plasma Astrophysics, K. U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Georgian National Astrophysical Observatory, 2a Kazbegi Ave., 0160 Tbilisi, Georgia (United States); Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Poedts, S. [Centre for Plasma Astrophysics, K. U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium)

2009-07-15T23:59:59.000Z

230

TURBULENT FRBRNNING MVK130 Turbulent Combustion  

E-Print Network (OSTI)

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

231

Petascale Simulations of Inhomogeneous Alfven Turbulence in the Solar Wind  

NLE Websites -- All DOE Office Websites (Extended Search)

A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii. Alfven waves (AW), launched by convective motions on the photosphere, propagate in the inhomogeneous Solar atmosphere producing primary reflected waves that interact non-linearly with the outward waves, driving a turbulent cascade. This cascade continues with secondary reflections in a very complex interplay between wave reflections and nonlinear interactions. Selected slices across the simulation domain show contours of plasma current, indicating the generation of small scale structures where the

232

Large-Eddy Simulation of Decaying Stably Stratified Turbulence  

Science Conference Proceedings (OSTI)

A large-eddy simulation (LES) model is developed and employed to study the interactions among turbulent and internal gravity wave motions in a uniformly stratified fluid at oceanic space and time scales. The decay of a random initial energy ...

David A. Siegel; J. Andrzej Domaradzki

1994-11-01T23:59:59.000Z

233

Planar Richtmyer-Meshkov instabilities and transition to turbulence  

Science Conference Proceedings (OSTI)

Extensive recent work has demonstrated that predictive under-resolved simulations of the velocity fields in turbulent flows are possible without resorting to explicit subgrid models. When using a class of physics-capturing high-resolution finite-volume numerical algorithms. This strategy is denoted implicit large eddy simulation (ILES, MILES). The performance of ILES in the substantially more difficult problem of under-resolved material mixing driven by under-resolved velocity fields and initial conditions (ICs) is a focus of the present work. Progress is presented in analyzing the effects of IC combined spectral content and thickness parametrizations. In the large eddy simulation (LES). the large energy containing structures are resolved, the smaller, presumably more isotropic, structures are filtered out, and effects of subgrid scales (SGS) are modeled. ILES effectively addresses the seemingly insurmountable issues posed to LES by under-resolution. by relying on the use of SGS modeling and filtering provided implicitly by a class of physics capturing numerics; extensive verification and validation in areas of engineering. geophysics. and astrophysics has been reported. In many areas of interest such as. inertial confinement fusion. understanding the collapse of the outer cores of supernovas. and supersonic combustion engines, vorticity is introduced at material interfaces by the impulsive loading of shock waves. and turbulence is generated via Richtmyer-Meshkov instabilities (RMI). Given that ILES is based on locally-adaptive, non-oscillatory. finite-volume methods it is naturally suited to emulate shock physics. The unique combination of shock and turbulence emulation capabilities supports direct use of ILES as an effective simulation anzatz for RMI. Here, we further test this approach using a particular strategy based on a nominally-inviscid, Schmidt number {approx} 1, simulation model that uses the LANL RAGE code to investigate planar RMI. Issues of initial material interface characterization and modeling difficulties, and effects of IC resolved spectral content on transitional and late-time turbulent mixing were examined in our previous work. The focus here is to carry out a systematic analysis of effects of combined IC spectral content and thickness.

Grinstein, Fernando F [Los Alamos National Laboratory; Gowardhan, Akshay [Los Alamos National Laboratory; Ristorcelli, Ray [Los Alamos National Laboratory

2011-01-21T23:59:59.000Z

234

Gyrokinetic turbulence: a nonlinear route to dissipation through phase space  

E-Print Network (OSTI)

This paper describes a conceptual framework for understanding kinetic plasma turbulence as a generalized form of energy cascade in phase space. It is emphasized that conversion of turbulent energy into thermodynamic heat is only achievable in the presence of some (however small) degree of collisionality. The smallness of the collision rate is compensated by the emergence of small-scale structure in the velocity space. For gyrokinetic turbulence, a nonlinear perpendicular phase mixing mechanism is identified and described as a turbulent cascade of entropy fluctuations simultaneously occurring at spatial scales smaller than the ion gyroscale and in velocity space. Scaling relations for the resulting fluctuation spectra are derived. An estimate for the collisional cutoff is provided. The importance of adequately modeling and resolving collisions in gyrokinetic simulations is biefly discussed, as well as the relevance of these results to understanding the dissipation-range turbulence in the solar wind and the electrostatic microturbulence in fusion plasmas.

A. A. Schekochihin; S. C. Cowley; W. Dorland; G. W. Hammett; G. G. Howes; G. G. Plunk; E. Quataert; T. Tatsuno

2008-06-05T23:59:59.000Z

235

Gravitational wave generation from bubble collisions in first-order phase transitions: an analytic approach  

E-Print Network (OSTI)

Gravitational wave production from bubble collisions was calculated in the early nineties using numerical simulations. In this paper, we present an alternative analytic estimate, relying on a different treatment of stochasticity. In our approach, we provide a model for the bubble velocity power spectrum, suitable for both detonations and deflagrations. From this, we derive the anisotropic stress and analytically solve the gravitational wave equation. We provide analytical formulae for the peak frequency and the shape of the spectrum which we compare with numerical estimates. In contrast to the previous analysis, we do not work in the envelope approximation. This paper focuses on a particular source of gravitational waves from phase transitions. In a companion article, we will add together the different sources of gravitational wave signals from phase transitions: bubble collisions, turbulence and magnetic fields and discuss the prospects for probing the electroweak phase transition at LISA.

Caprini, Chiara; Servant, Géraldine

2008-01-01T23:59:59.000Z

236

Gravitational wave generation from bubble collisions in first-order phase transitions: an analytic approach  

E-Print Network (OSTI)

Gravitational wave production from bubble collisions was calculated in the early nineties using numerical simulations. In this paper, we present an alternative analytic estimate, relying on a different treatment of stochasticity. In our approach, we provide a model for the bubble velocity power spectrum, suitable for both detonations and deflagrations. From this, we derive the anisotropic stress and analytically solve the gravitational wave equation. We provide analytical formulae for the peak frequency and the shape of the spectrum which we compare with numerical estimates. In contrast to the previous analysis, we do not work in the envelope approximation. This paper focuses on a particular source of gravitational waves from phase transitions. In a companion article, we will add together the different sources of gravitational wave signals from phase transitions: bubble collisions, turbulence and magnetic fields and discuss the prospects for probing the electroweak phase transition at LISA.

Chiara Caprini; Ruth Durrer; Geraldine Servant

2007-11-16T23:59:59.000Z

237

Influence of the inlet velocity profiles on the prediction of velocity distribution inside an electrostatic precipitator  

SciTech Connect

The influence of the velocity profile at the inlet boundary on the simulation of air velocity distribution inside an electrostatic precipitator is presented in this study. Measurements and simulations were performed in a duct and an electrostatic precipitator (ESP). A four-hole cobra probe was used for the measurement of velocity distribution. The flow simulation was performed by using the computational fluid dynamics (CFD) code FLUENT. Numerical calculations for the air flow were carried out by solving the Reynolds-averaged Navier-Stokes equations coupled with the realizable k-{epsilon} turbulence model equations. Simulations were performed with two different velocity profiles at the inlet boundary - one with a uniform (ideal) velocity profile and the other with a non-uniform (real) velocity profile to demonstrate the effect of velocity inlet boundary condition on the flow simulation results inside an ESP. The real velocity profile was obtained from the velocity measured at different points of the inlet boundary whereas the ideal velocity profile was obtained by calculating the mean value of the measured data. Simulation with the real velocity profile at the inlet boundary was found to predict better the velocity distribution inside the ESP suggesting that an experimentally measured velocity profile could be used as velocity inlet boundary condition for an accurate numerical simulation of the ESP. (author)

Haque, Shah M.E.; Deev, A.V.; Subaschandar, N. [Process Engineering and Light Metals (PELM) Centre, Faculty of Sciences, Engineering and Health, Central Queensland University, Gladstone, Queensland 4680 (Australia); Rasul, M.G.; Khan, M.M.K. [College of Engineering and Built Environment, Faculty of Sciences, Engineering and Health, Central Queensland University, Rockhampton, Queensland 4702 (Australia)

2009-01-15T23:59:59.000Z

238

ENERGETIC PARTICLE DIFFUSION IN STRUCTURED TURBULENCE  

Science Conference Proceedings (OSTI)

In the full-orbit particle simulations of energetic particle transport in plasmas, the plasma turbulence is typically described as a homogeneous superposition of linear Fourier modes. The turbulence evolution is, however, typically a nonlinear process, and, particularly in the heliospheric context, the solar wind plasma is inhomogeneous due to the transient structures, as observed by remote and in situ measurements. In this work, we study the effects of the inhomogeneities on energetic particle transport by using spatially distributed, superposed turbulence envelopes. We find that the cross-field transport is significantly reduced, when compared to the results obtained with homogeneous turbulence. The reduction can reach an order of magnitude when the enveloping breaks the wave phase coherence along the mean magnetic field direction.

Laitinen, T.; Dalla, S.; Kelly, J. [Jeremiah Horrocks Institute, University of Central Lancashire, PR1 2HE Preston (United Kingdom)

2012-04-20T23:59:59.000Z

239

Fluid dynamics of bacterial turbulence  

E-Print Network (OSTI)

Self-sustained turbulent structures have been observed in a wide range of living fluids, yet no quantitative theory exists to explain their properties. We report experiments on active turbulence in highly concentrated 3D suspensions of Bacillus subtilis and compare them with a minimal fourth-order vector-field theory for incompressible bacterial dynamics. Velocimetry of bacteria and surrounding fluid, determined by imaging cells and tracking colloidal tracers, yields consistent results for velocity statistics and correlations over two orders of magnitude in kinetic energy, revealing a decrease of fluid memory with increasing swimming activity and linear scaling between energy and enstrophy. The best-fit model parameters allow for quantitative agreement with experimental data.

Jörn Dunkel; Sebastian Heidenreich; Knut Drescher; Henricus H. Wensink; Markus Bär; Raymond E. Goldstein

2013-02-21T23:59:59.000Z

240

Can Wind Lidars Measure Turbulence?  

Science Conference Proceedings (OSTI)

Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model ...

A. Sathe; J. Mann; J. Gottschall; M. S. Courtney

2011-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Rotational intermittency and turbulence induced lift experienced by large particles in a turbulent flow  

E-Print Network (OSTI)

The motion of a large, neutrally buoyant, particle, freely advected by a turbulent flow is determined experimentally. We demonstrate that both the translational and angular accelerations exhibit very wide probability distributions, a manifestation of intermittency. The orientation of the angular velocity with respect to the trajectory, as well as the translational acceleration conditioned on the spinning velocity provide evidence of a lift force acting on the particle.

Zimmermann, Robert; Bourgoin, Mickael; Volk, Romain; Pumir, Alain; Pinton, Jean-Francois

2010-01-01T23:59:59.000Z

242

Three-dimensional Fast Flux Test Facility plenum model turbulent flow prediction and data comparison  

Science Conference Proceedings (OSTI)

Two- and three-dimensional numerical simulations of turbulent flow in a scaled Fast Flux Test Facility (FFTF) upper plenum model were performed using the TEMPEST hydrothermal code. A standard k-element of model was used to describe turbulence through an effective viscosity. Comparisons with previously reported mean velocity and turbulence field data measured in the plenum model and two-dimensional numerical simulations using the TEACH code were made. Predicted horizontal and vertical mean velocities and turbulent kinetic energy are shown to be in good agreement with available experimental data when inlet conditions of the dissipation of turbulent kinetic energy are appropriately prescribed. The three-dimensional quarter-symmetry simulation predicts the turbulent kinetic energy field significantly better than the two-dimensional centerplane simulations. These results lead to conclusions concerning deficiencies in the experimental data and the turbulence model.

Eyler, L.L.; Sawdye, R.W.

1981-01-01T23:59:59.000Z

243

Temporal Velocity Variations beneath the Coso Geothermal Field...  

Open Energy Info (EERE)

events and determine the compressional and shear wave velocity as well as their ratio. In a first step, we apply traveltime tomography based on the observed microearthquake...

244

Effect of Initial Conditions on 2D Rayleigh-Taylor Instability and Transition to Turbulence in Planar Blast-wave-driven Systems  

Science Conference Proceedings (OSTI)

Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, we present the first results from a computational study of such a system under drive conditions to be attainable on the National Ignition Facility. Using the multiphysics, AMR, higher order Godunov Eulerian hydrocode, Raptor, we consider the late nonlinear instability evolution for multiple amplitude and phase realizations of a variety of multimode spectral types. We show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions by allowing for memory of the initial conditions to be retained in the mix width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. Certain aspects of the initial conditions, including the rms amplitude, are shown to have a strong effect on the time to transition to the quasi-self-similar regime.

Miles, A R; Edwards, M J; Greenough, J A

2004-03-26T23:59:59.000Z

246

Topographic Waves Generated by a Transient Wind  

Science Conference Proceedings (OSTI)

The concept of linear mountain waves is generally equated with steady-state stationary waves. This essentially means that the absolute horizontal phase velocity of mountain waves is zero and that their momentum flux profile is independent of ...

François Lott; Hector Teitelbaum

1993-08-01T23:59:59.000Z

247

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

248

Measurements of Ocean Surface Turbulence and Wave–Turbulence Interactions  

Science Conference Proceedings (OSTI)

The uppermost layers of the ocean, along with the lower atmospheric boundary layer, play a crucial role in the air–sea fluxes of momentum, heat, and mass, thereby providing important boundary conditions for both the atmosphere and the ocean that ...

Fabrice Veron; W. Kendall Melville; Luc Lenain

2009-09-01T23:59:59.000Z

249

TURBULENT FRBRNNING MVK 130 Turbulent Combustion  

E-Print Network (OSTI)

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

250

Quantum Gravity and Turbulence  

E-Print Network (OSTI)

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

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

2010-05-18T23:59:59.000Z

251

On the motion of the center of mass of a spherical turbulent premixed flame  

DOE Green Energy (OSTI)

The movement of the center of mass of a premixed statistically spherical flame in the wrinkled-laminar flame regime has been examined. When the flame is small (or comparable) to the integral scale of the turbulence, the flame ball is convected as a whole by the turbulent eddy. When the flame grows to a size large compared to the integral scale, the flame center of motion is not affected by the turbulence. This phenomenon has been explained in terms of the phase coherence of the local turbulent convection velocity at the flame front. When the flame is small, the turbulent velocity is coherent over the entire flame surface; as a result, the flame is convected as a whole by the turbulent eddy. When the flame is large, the velocity at the different area elements of the flame front is independent of each other. The center of mass velocity, which is an aggregate of the velocities at the different elements, therefore, tends to the mean velocity and is independent of the turbulence. A theory for predicting the variance of the flame center velocity has been developed. The prediction is in good agreement with the experimental results. 12 refs., 5 figs.

Cheng, W. K.; Hainsworth, E.

1988-01-01T23:59:59.000Z

252

The Statistics of Supersonic Isothermal Turbulence  

E-Print Network (OSTI)

We present results of large-scale three-dimensional simulations of supersonic Euler turbulence with the piecewise parabolic method (PPM) and multiple grid resolutions up to 2048^3 points. Our numerical experiments describe non-magnetized driven turbulent flows with an isothermal equation of state and an rms Mach number of 6. We discuss numerical resolution issues and demonstrate convergence, in a statistical sense, of the inertial range dynamics in simulations on grids larger than 512^3 points. The simulations allowed us to measure the absolute velocity scaling exponents for the first time. The inertial range velocity scaling in this strongly compressible regime deviates substantially from the incompressible Kolmogorov laws. The slope of the velocity power spectrum, for instance, is -1.95 compared to -5/3 in the incompressible case. The exponent of the third-order velocity structure function is 1.28, while in incompressible turbulence it is known to be unity. We propose a natural extension of Kolmogorov's phe...

Kritsuk, Alexei G; Padoan, Paolo; Wagner, Rick

2007-01-01T23:59:59.000Z

253

Mixing in Symmetric Holmboe Waves  

Science Conference Proceedings (OSTI)

Direct simulations are used to study turbulence and mixing in Holmboe waves. Previous results showing that mixing in Holmboe waves is comparable to that found in the better-known Kelvin–Helmholtz (KH) billows are extended to cover a range of ...

W. D. Smyth; J. R. Carpenter; G. A. Lawrence

2007-06-01T23:59:59.000Z

254

Momentum Transport by Gravity Waves  

Science Conference Proceedings (OSTI)

The momentum flux by orographic gravity waves and the turbulent heat flux in wave-breaking regions are estimated from aircraft data from ALPEX. The fluxes on 6 March 1982 are controlled by low-level directional shear of the mean flow and ...

Jinwon Kim; L. Mahrt

1992-05-01T23:59:59.000Z

255

Wave Breaking and Ocean Surface Layer Thermal Response  

Science Conference Proceedings (OSTI)

The effect of breaking waves on ocean surface temperatures and surface boundary layer deepening is investigated. The modification of the Mellor–Yamada turbulence closure model by Craig and Banner and others to include surface wave breaking ...

George Mellor; Alan Blumberg

2004-03-01T23:59:59.000Z

256

Observations of Wave Breaking Kinematics in Fetch-Limited Seas  

Science Conference Proceedings (OSTI)

Breaking waves play an important role in air–sea interaction, enhancing momentum flux from the atmosphere to the ocean, dissipating wave energy that is then available for turbulent mixing, injecting aerosols and sea spray into the atmosphere, and ...

Jessica M. Kleiss; W. Kendall Melville

2010-12-01T23:59:59.000Z

257

On the Energy Input from Wind to Surface Waves  

Science Conference Proceedings (OSTI)

A basic model relating the energy dissipation in the ocean mixed layer to the energy input into the surface wave field is combined with recent measurements of turbulent kinetic energy dissipation to determine the average phase speed of the waves ...

J. R. Gemmrich; T. D. Mudge; V. D. Polonichko

1994-11-01T23:59:59.000Z

258

Wave Breaking Dissipation in a Young Wind Sea  

Science Conference Proceedings (OSTI)

Coupled in situ and remote sensing measurements of young, strongly-forced, wind waves are applied to assess the role of breaking in an evolving wavefield. In situ measurements of turbulent energy dissipation from wave-following “SWIFT” drifters ...

Michael Schwendeman; Jim Thomson; Johannes R. Gemmrich

259

Modeling Compressed Turbulence  

Science Conference Proceedings (OSTI)

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

Israel, Daniel M. [Los Alamos National Laboratory

2012-07-13T23:59:59.000Z

260

Experimental study of premixed flames in intense isotropic turbulence  

SciTech Connect

A methodology for investigating premixed turbulent flames propagating in intense isotropic turbulence has been developed. The burner uses a turbulence generator developed by Videto and Santavicca and the flame is stabilized by weak-swirl generated by air injectors. This set-up produces stable premixed turbulent flames under a wide range of mixture conditions and turbulence intensities. The experiments are designed to investigate systematically the changes in flame structures for conditions which can be classified as wrinkled laminar flames, corrugated flames and flames with distributed reaction zones. Laser Doppler anemometry and Rayleigh scattering techniques are used to determine the turbulence and scalar statistics. In the intense turbulence, the flames are found to produce very little changes in the mean and rams velocities. Their flame speed increase linearly with turbulence intensity as for wrinkled laminar flames. The Rayleigh scattering pdfs for flames within the distributed reaction zone regime are distinctly bimodal. The probabilities of the reacting states (i.e. contributions from within the reaction zone) is not higher than those of wrinkled laminar flame. These results show that there is no drastic changes in flame structures at Karlovitz number close to unity. This suggest that the Klimov-Williams criterion under-predicts the resilience of wrinkled flamelets to intense turbulence.

Bedat, B.; Cheng, R.K.

1994-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Evaluation and Performance Enhancement of a Pressure Transducer under Flows, Waves, and a Combination of Flows and Waves  

Science Conference Proceedings (OSTI)

The performance of a pressure transducer, with its inlet attached to differing hydromechanical front ends, has been evaluated in flow flume and wave flume experiments in which laminar and turbulent flows, and regular progressive gravity waves and ...

Antony Joseph; J. A. Erwin Desa; Peter Foden; Kevin Taylor; Jim McKeown; Ehrlich Desa

2000-03-01T23:59:59.000Z

262

Large-Scale Eddies in the Unstably Stratified Atmospheric Surface Layer. Part II: Turbulent Pressure Fluctuations and the Budgets of Heat Flux, Stress and Turbulent Kinetic Energy  

Science Conference Proceedings (OSTI)

A method is developed for retrieving turbulent pressure fluctuations from tower measurements of velocity and temperature, through use of the equations of motion. This method is applied to a series of large-scale eddies which are defined by their ...

J. M. Wilczak; Joost A. Businger

1984-12-01T23:59:59.000Z

263

Turbulence process domination under the combined forcings of wind stress, the Langmuir vortex force, and surface cooling  

Science Conference Proceedings (OSTI)

Turbulence in the ocean surface layer is generated by time-varying combinations of destabilizing surface buoyancy flux, wind stress forcing, and wave forcing through a vortex force associated with the surface wave field. Observations of time- and ...

A. E. Gargett; C. E. Grosch

264

Statistical theory of turbulent incompressible multimaterial flow  

Science Conference Proceedings (OSTI)

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

Kashiwa, B.

1987-10-01T23:59:59.000Z

265

Scaling Relations for Turbulence in Multiphase Interstellar Medium  

E-Print Network (OSTI)

We simulate the dynamics of phase transition in radiatively cooling interstellar gas in three dimensions with a high order hydrodynamic method. We have previously shown (Kritsuk & Norman 2002a) in simulations with non-equilibrium initial conditions that thermal instability induces supersonic turbulence as a by-product of the phase transition which leads to formation of multiphase medium. We rely on a generalization of the She & Leveque (1994) model to study velocity scaling relations in this decaying turbulence and compare those with analogous results for compressible isothermal turbulence. Since radiative cooling promotes nonlinear instabilities in highly supersonic flows, turbulence in our simulations tends to be more intermittent than in the isothermal case. Hausdorff dimension of the most singular dissipative structures, D, can be as high as 2.3, while in supersonic isothermal turbulence D is limited by a more primitive nature of dissipation (shocks): D<=2. We also show that single-phase veloci...

Kritsuk, A G; Kritsuk, Alexei G.; Norman, Michael L.

2004-01-01T23:59:59.000Z

266

FORMATION OF TURBULENT AND MAGNETIZED MOLECULAR CLOUDS VIA ACCRETION FLOWS OF H I CLOUDS  

Science Conference Proceedings (OSTI)

Using three-dimensional magnetohydrodynamic simulations, including the effects of radiative cooling/heating, chemical reactions, and thermal conduction, we investigate the formation of molecular clouds in the multi-phase interstellar medium. As suggested by recent observations, we consider the formation of molecular clouds due to accretion of H I clouds. Our simulations show that the initial H I medium is piled up behind the shock waves induced by accretion flows. Since the initial medium is highly inhomogeneous as a consequence of thermal instability, a newly formed molecular cloud becomes very turbulent owing to the development of the Richtmyer-Meshkov instability. The kinetic energy of the turbulence dominates the thermal, magnetic, and gravitational energies throughout the entire 10 Myr evolution. However, the kinetic energy measured using CO-fraction-weighted densities is comparable to the other energies, once the CO molecules are sufficiently formed as a result of UV shielding. This suggests that the true kinetic energy of turbulence in molecular clouds as a whole can be much larger than the kinetic energy of turbulence estimated using line widths of molecular emission. We find that clumps in a molecular cloud show the following statistically homogeneous evolution: the typical plasma {beta} of the clumps is roughly constant ({beta}) {approx_equal} 0.4; the size-velocity dispersion relation is {Delta}v {approx_equal} 1.5 km s{sup -1} (l/1 pc){sup 0.5}, irrespective of the density; the clumps evolve toward magnetically supercritical, gravitationally unstable cores; and the clumps seem to evolve into cores that satisfy the condition for fragmentation into binaries. These statistical properties may represent the initial conditions of star formation.

Inoue, Tsuyoshi [Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku, Sagamihara 252-5258 (Japan); Inutsuka, Shu-ichiro, E-mail: inouety@phys.aoyama.ac.jp [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

2012-11-01T23:59:59.000Z

267

Decay of a Near-Inertial Wave  

Science Conference Proceedings (OSTI)

The decay of a downward propagating near-inertial wave was observed over four days. During this short period, the energy of the near-inertial wave decreased by 70%. The shear layers produced by the wave were regions of enhanced turbulent ...

Dave Hebert; J. N. Moum

1994-11-01T23:59:59.000Z

268

Premixed turbulent combustion to opposed streams  

DOE Green Energy (OSTI)

Premixed turbulent combustion in opposed streams has been studied experimentally by the use of two component laser doppler aneomometry. This flow geometry is part of a class of stagnating flows used to study turbulent combustion in recent years. It does not involve any surface near the flames because of the flow symmetry thus circumventing many of the effects of flame surface interaction. The mean non-reacting flow is found to be self-similar for all the conditions studied in this and the stagnation plate configuration. A homogeneous region of plane straining is produced in the vicinity of the stagnation and there is a strong interaction between the turbulence in the flow and the mean straining which can increase the rms velocity as the flow stagnates. The reacting flow fields are found to be symmetric about the free stagnation point. The traverses of mean axial velocity in the stagnation streamlines for reaction flows are not dramatically different from the non-reaction flows. These results differ from turbulent combustion experiments where the flow is stagnated by a flat plate. The extinction limits was studied for propane:air mixtures. 11 refs.

Kostiuk, L.W.; Cheng, R.K.

1992-03-01T23:59:59.000Z

269

Turbulence in the Molecular Interstellar Medium  

E-Print Network (OSTI)

Abstract. The observational record of turbulence within the molecular gas phase of the interstellar medium is summarized. We briefly review the analysis methods used to recover the velocity structure function from spectroscopic imaging and the application of these tools on sets of cloud data. These studies identify a near-invariant velocity structure function that is independent of local the environment and star formation activity. Such universality accounts for the cloud-to-cloud scaling law between the global line-width and size of molecular clouds found by Larson (1981) and constrains the degree to which supersonic turbulence can regulate star formation. In addition, the evidence for large scale driving sources necessary to sustain supersonic flows is summarized.

Mark H. Heyer; Chris Brunt

2006-01-01T23:59:59.000Z

270

Turbulence structure in a Taylor-Couette apparatus  

SciTech Connect

Turbulence measurements were made in a Taylor-Couette apparatus as a basis for future flame propagation studies. Results of the present study extend that of earlier work by more complete characterization of the featureless turbulence regime generated by the Taylor-Couette apparatus. Laser Doppler Velocimetry was used to measure Reynolds stresses, integral and micro time scales and power spectra over a wide range of turbulence intensities typically encountered by turbulent pre-mixed hydrocarbon-air flames. Measurements of radial velocity intensities are consistent with earlier axial and circumferential velocity measurements that indicated a linear relationship between turbulence intensity and the Reynolds number based on the average cylinder rotation speed and wall separation distance. Measured integral and micro time scales and approximated integral length scales were all found to decrease with the Reynolds number, possibly associated with a confinement of the largest scales (of the order of the cylinder wall separation distance). Regions of transverse isotropy were discovered in axial-radial cross correlations for average cylinder Reynolds numbers less than 6000 and are predicted to exist also for circumferential cross correlations at higher average Reynolds numbers, greater than 6000. Power spectra for the independent directions of velocity fluctuation exhibited -5/3 slopes, suggesting that the flow also has some additional isotropic characteristics and demonstrating the role of the Taylor-Couette apparatus as a novel means for generating turbulence for flame propagation studies. (author)

Fehrenbacher, Noah; Aldredge, Ralph C.; Morgan, Joshua T. [Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616 (United States)

2007-10-15T23:59:59.000Z

271

The Statistics of Supersonic Isothermal Turbulence  

E-Print Network (OSTI)

We present results of large-scale three-dimensional simulations of supersonic Euler turbulence with the piecewise parabolic method and multiple grid resolutions up to 2048^3 points. Our numerical experiments describe non-magnetized driven turbulent flows with an isothermal equation of state and an rms Mach number of 6. We discuss numerical resolution issues and demonstrate convergence, in a statistical sense, of the inertial range dynamics in simulations on grids larger than 512^3 points. The simulations allowed us to measure the absolute velocity scaling exponents for the first time. The inertial range velocity scaling in this strongly compressible regime deviates substantially from the incompressible Kolmogorov laws. The slope of the velocity power spectrum, for instance, is -1.95 compared to -5/3 in the incompressible case. The exponent of the third-order velocity structure function is 1.28, while in incompressible turbulence it is known to be unity. We propose a natural extension of Kolmogorov's phenomenology that takes into account compressibility by mixing the velocity and density statistics and preserves the Kolmogorov scaling of the power spectrum and structure functions of the density-weighted velocity v=\\rho^{1/3}u. The low-order statistics of v appear to be invariant with respect to changes in the Mach number. For instance, at Mach 6 the slope of the power spectrum of v is -1.69, and the exponent of the third-order structure function of v is unity. We also directly measure the mass dimension of the "fractal" density distribution in the inertial subrange, D_m = 2.4, which is similar to the observed fractal dimension of molecular clouds and agrees well with the cascade phenomenology.

Alexei G. Kritsuk; Michael L. Norman; Paolo Padoan; Rick Wagner

2007-04-29T23:59:59.000Z

272

Heat release effects on decaying homogeneous compressible turbulence  

E-Print Network (OSTI)

High Mach-number compressible flows with heat release are inherently more complicated than incompressible flows due to, among other reasons, the activation of the thermal energy mode. Such flow fields can experience significant fluctuations in density, temperature, viscosity, conductivity and specific heat, which affect velocity and pressure fluctuations. Furthermore, the flow field cannot be assumed to be dilatation-free in high Mach numbers and even in low Mach-number flows involving combustion, or in boundary layers on heated walls. The main issue in these high-speed and highly-compressible flows is the effect of thermal gradients and fluctuations on turbulence. The thermal field has various routes through which it affects flow structures of compressible turbulence. First, it has direct influence through pressure, which affects turbulence via pressure-strain correlation. The indirect effects of thermal fields on compressible turbulence are through the changes in flow properties. The high temperature gradients alter the transport coefficient and compressibility of the flow. The objective of this work is to answer the following questions: How do temperature fluctuations change the compressible flow structure and energetics? How does compressibility in the flow affect the non-linear pressure redistribution process? What is the main effect of spatial transport-coefficient variation? We perform direct numerical simulations (DNS) to answer the above questions. The investigations are categorized into four parts: 1) Turbulent energy cascade and kinetic-internal energy interactions under the influence of temperature fluctuations; 2) Return-to-isotropy of anisotropic turbulence under the influence of large temperature fluctuations; 3) The effect of turbulent Mach number and dilatation level on small-scale (velocity-gradient) dynamics; 4) The effect of variable transport-coefficients (viscosity and diffusivity) on cascade and dissipation processes of turbulence. The findings lead to a better understanding of temperature fluctuation effects on non-linear processes in compressible turbulence. This improved understanding is expected to provide direction for improving second-order closure models of compressible turbulence.

Lee, Kurn Chul

2008-05-01T23:59:59.000Z

273

Prediction of turbulence control for arbitrary periodic spanwise wall movement  

E-Print Network (OSTI)

In order to generalize the well-known spanwise-oscillating-wall technique for drag reduction, non-sinusoidal oscillations of a solid wall are considered as a means to alter the skin-friction drag in a turbulent channel flow. A series of Direct Numerical Simulations is conducted to evaluate the control performance of nine different temporal waveforms, in addition to the usual sinusoid, systematically changing the wave amplitude and the period for each waveform. The turbulent average spanwise motion is found to coincide with the laminar Stokes solution that is constructed, for the generic waveform, through harmonic superposition. This allows us to define and compute, for each waveform, a new penetration depth of the Stokes layer which correlates with the amount of turbulent drag reduction, and eventually to predict both turbulent drag reduction and net energy saving rate for arbitrary waveforms. Among the waveforms considered, the maximum net energy saving rate is obtained by the sinusoidal wave at its optimal ...

Cimarelli, Andrea; Hasegawa, Yosuke; De Angelis, Elisabetta; Quadrio, Maurizio

2013-01-01T23:59:59.000Z

274

Displacement speeds in turbulent premixed flame simulations  

SciTech Connect

The theory of turbulent premixed flames is based on acharacterization of the flame as a discontinuous surface propagatingthrough the fluid. The displacement speed, defined as the local speed ofthe flame front normal to itself, relative to the unburned fluid,provides one characterization of the burning velocity. In this paper, weintroduce a geometric approach to computing displacement speed anddiscuss the efficacy of the displacement speed for characterizing aturbulent flame.

Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

2007-07-01T23:59:59.000Z

275

Clustering of Aerosols in Atmospheric Turbulent Flow  

E-Print Network (OSTI)

A mechanism of formation of small-scale inhomogeneities in spatial distributions of aerosols and droplets associated with clustering instability in the atmospheric turbulent flow is discussed. The particle clustering is a consequence of a spontaneous breakdown of their homogeneous space distribution due to the clustering instability, and is caused by a combined effect of the particle inertia and a finite correlation time of the turbulent velocity field. In this paper a theoretical approach proposed in Phys. Rev. E 66, 036302 (2002) is further developed and applied to investigate the mechanisms of formation of small-scale aerosol inhomogeneities in the atmospheric turbulent flow. The theory of the particle clustering instability is extended to the case when the particle Stokes time is larger than the Kolmogorov time scale, but is much smaller than the correlation time at the integral scale of turbulence. We determined the criterion of the clustering instability for the Stokes number larger than 1. We discussed applications of the analyzed effects to the dynamics of aerosols and droplets in the atmospheric turbulent flow.

T. Elperin; N. Kleeorin; M. A. Liberman; V. L'vov; I. Rogachevskii

2007-02-15T23:59:59.000Z

276

Understanding Galaxy Outflows as the Product of Unstable Turbulent Support  

E-Print Network (OSTI)

The interstellar medium is a multiphase gas in which turbulent support is as important as thermal pressure. Sustaining this configuration requires both continuous turbulent stirring and continuous radiative cooling to match the decay of turbulent energy. While this equilibrium can persist for small turbulent velocities, if the one-dimensional velocity dispersion is larger than approximately 35 km/s, the gas moves into an unstable regime that leads to rapid heating. I study the implications of this turbulent runaway, showing that it causes a hot gas outflow to form in all galaxies with a gas surface density above approximately 50 solar masses/pc^2 corresponding to a star formation rate per unit area of 0.1$ solar masses/yr/kpc^2. For galaxies with escape velocities above 200 km/s, the sonic point of this hot outflow should lie interior to the region containing cold gas and stars, while for galaxies with smaller escape velocities, the sonic point should lie outside this region. This leads to efficient cold clou...

Scannapieco, Evan

2013-01-01T23:59:59.000Z

277

DRIFT COEFFICIENTS OF CHARGED PARTICLES IN TURBULENT MAGNETIC FIELDS  

Science Conference Proceedings (OSTI)

Using test-particle simulations, the off-diagonal elements of the diffusion tensor are evaluated numerically. The comparison of the so-obtained time-dependent drift coefficients with analytical approximations shows that, for weak turbulence strengths or for slab turbulence geometry, the weak scattering result provides an excellent agreement with the numerical results. For two- or three-dimensional turbulence geometry, however, neither the classical scattering result nor alternative analytical approaches provide an accurate description of the numerically obtained values. Furthermore, the influence is discussed of a non-constant energy range in the turbulence spectrum and of non-static turbulence, for which the time dependence is modeled using magnetohydrodynamic plasma waves.

Tautz, R. C. [Zentrum fuer Astronomie und Astrophysik, Technische Universitaet Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany); Shalchi, A., E-mail: rct@tp4.rub.de, E-mail: andreasm4@yahoo.com [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2012-01-10T23:59:59.000Z

278

Closure in Turbulence from first principles  

E-Print Network (OSTI)

It has been recently demonstrated, [3], that according to the principle of release of constraints, absence of shear stresses in the Euler equations must be compensated by additional degrees of freedom, and that led to a Reynolds-type enlarged Euler equations (EE equations) with a doublevalued velocity field that do not require any closures. In the first part of the paper, the theory is applies to turbulent mixing and illustrated by propagation of mixing zone triggered by a tangential jump of velocity. A comparison of the proposed solution with the Prandtl's solutions is performed and discussed. In the second part of the paper, a semi-viscose version of the Navier-Stokes equations is introduced. The model does not require any closures since the number of equations is equal to the number of unknowns. Special attention is paid to transition from laminar to turbulent state. The analytical solution for this transition demonstrates the turbulent mean velocity profile that qualitatively similar to the celebrated logarithmic law.

Michail Zak

2012-12-26T23:59:59.000Z

279

Burgulence and Alfven waves heating mechanism of solar corona  

E-Print Network (OSTI)

Heating of magnetized turbulent plasma is calculated in the framework of Burgers turbulence [A.M. Polyakov, Phys. Rev. E. 52, 6183 (1995)]. Explicit formula for the energy flux of Alfven waves along the magnetic field is presented. The Alfven waves are considered as intermediary between the turbulent energy and the heat. The derived results are related to a wave channel of heating of the solar corona. If we incorporate amplification of Alfven waves by shear flow the suggested model of heating can be applied to analysis of the missing viscosity of accretion discs and to reveal why the quasars are the most powerful sources of light in the universe. We suppose that the Langevin-Burgers approach to turbulence we have applied in the current work can be also helpful for other systems where we have intensive interaction between a stochastic turbulent system and waves and can be used in many multidisciplinary researches in hydrodynamics and MHD.

T. M. Mishonov; Y. G. Maneva

2006-09-21T23:59:59.000Z

280

Overview of the TurbSim Stochastic Inflow Turbulence Simulator: Version 1.10  

DOE Green Energy (OSTI)

The Turbsim stochastic inflow turbulence code was developed to provide a numerical simulation of a full-field flow that contains coherent turbulence structures that reflect the proper spatiotemporal turbulent velocity field relationships seen in instabilities associated with nocturnal boundary layer flows. This report provides the user with an overview of how the TurbSim code has been developed and some of the theory behind that development.

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

2006-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Wave Mechanics and the Fifth Dimension  

E-Print Network (OSTI)

Replacing 4D Minkowski space by 5D canonical space leads to a clearer derivation of the main features of wave mechanics, including the wave function and the velocity of de Broglie waves. Recent tests of wave-particle duality could be adapted to investigate whether de Broglie waves are basically 4D or 5D in nature.

Paul S. Wesson; James M. Overduin

2013-01-28T23:59:59.000Z

282

Hard particle spectra from parallel shocks due to turbulence transmission  

E-Print Network (OSTI)

If taken into account, the transmission of the particle-scattering turbulence --in addition to just the particles-- through the shock front can change the effective compression ratio felt by the accelerating particles significantly from the compression of the underlying plasma. This can lead to significantly harder energy spectra than what are traditionally predicted assuming frozen-in turbulence. I consider the applicability and limitations of turbulence transmission scenario in parallel shock waves of different thickness, its consequences in AGN and microquasar environments, and discuss the possible effects to the spectrum of the accelerated particles.

Joni Tammi

2007-12-11T23:59:59.000Z

283

On apparent temperature in low-frequency Alfvenic turbulence  

SciTech Connect

Low-frequency, parallel propagating Alfvenic turbulence in collisionless plasmas is theoretically studied. Alfvenic turbulence is derived as an equilibrium state (Beltrami field) in the magnetohydrodynamic equations with the pressure anisotropy and multi-species of ions. It is shown that the conservation of the total 'apparent temperature' corresponds to the Bernoulli law. A simple model of the radially expanding solar wind including Alfvenic turbulence is also discussed. The conversion of the wave energy in the 'apparent temperature' into the 'real temperature' is facilitated with increasing radial distance.

Nariyuki, Yasuhiro [Faculty of Human Development, University of Toyama, 3190, Toyama City, Toyama 930-8555 (Japan)

2012-08-15T23:59:59.000Z

284

The Effect of Nonlinear Drag on the Motion and Settling Velocity of Heavy Particles  

Science Conference Proceedings (OSTI)

The effects of nonlinear drag on the motion and settling velocity of heavy particles in a turbulent atmosphere are investigated. The authors approach the problem rather systematically by first considering the response of particles to much simpler ...

J. E. Stout; S. P. Arya; E. L. Genikhovich

1995-11-01T23:59:59.000Z

285

Simultaneous Velocity Ambiguity Resolution and Noise Suppression for Multifrequency Coherent Doppler Sonar  

Science Conference Proceedings (OSTI)

Coherent Doppler sonar is a useful tool for noninvasive measurement of ocean currents, sediment transport, and turbulence in coastal environments. Various methods have been proposed to separately address two of its inherent limitations: velocity ...

Jeremy Dillon; Len Zedel; Alex E. Hay

2012-03-01T23:59:59.000Z

286

COLLISIONLESS DAMPING AT ELECTRON SCALES IN SOLAR WIND TURBULENCE  

SciTech Connect

The dissipation of turbulence in the weakly collisional solar wind plasma is governed by unknown kinetic mechanisms. Two candidates have been suggested to play an important role in the dissipation, collisionless damping via wave-particle interactions and dissipation in small-scale current sheets. High resolution spacecraft measurements of the turbulent magnetic energy spectrum provide important constraints on the dissipation mechanism. The limitations of popular fluid and hybrid numerical schemes for simulation of the dissipation of solar wind turbulence are discussed, and instead a three-dimensional kinetic approach is recommended. We present a three-dimensional nonlinear gyrokinetic simulation of solar wind turbulence at electron scales that quantitatively reproduces the exponential form of the turbulent magnetic energy spectrum measured in the solar wind. A weakened cascade model that accounts for nonlocal interactions and collisionless Landau damping also quantitatively agrees with the observed exponential form. These results establish that a turbulent cascade of kinetic Alfven waves that is terminated by collisionless Landau damping is sufficient to explain the observed magnetic energy spectrum in the dissipation range of solar wind turbulence.

TenBarge, J. M.; Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Dorland, W., E-mail: jason-tenbarge@uiowa.edu [Department of Physics, University of Maryland, College Park, MA 20742-3511 (United States)

2013-09-10T23:59:59.000Z

287

Radiosonde measurements of turbulence  

NLE Websites -- All DOE Office Websites (Extended Search)

at Cranwell, Lincolnshire, W. H. Pick and G. A. Bull, 1926. 3 Talk structure * Geomagnetic sensors to measure orientation * Orientation variability as a turbulence measure *...

288

Wind Mixing In a Turbulent Surface Layer in the Presence of a Horizontal Density Gradient  

Science Conference Proceedings (OSTI)

The effect of a horizontal density gradient of buoyancy on the turbulent kinetic energy budget of the surface mixed layer in the ocean is discussed. The combination of a horizontal buoyancy gradient and a vertical shear of the horizontal velocity ...

Johan Rodhe

1991-07-01T23:59:59.000Z

289

Aircraft Measurements of Turbulence Spectra in the Marine Stratocumulus-topped Boundary Layer  

Science Conference Proceedings (OSTI)

Mixed-layer scaling was successfully applied to the velocity, temperature, and moisture spectra of the marine stratocumulus-topped mixed layers observed during the First ISCCP Regional Experiment (FIRE). These turbulence spectra provide ...

Jeffrey J. Nucciarone; George S. Young

1991-11-01T23:59:59.000Z

290

Use of the Inertial Dissipation Method for Calculating Turbulent Fluxes from Low-Level Airborne Measurements  

Science Conference Proceedings (OSTI)

Airborne measurements are currently used for computing turbulence fluxes of heat and momentum. The method generally used is the eddy correlation technique, which requires sophisticated equipments to calculate the absolute velocities of the air. ...

Pierre Durand; Leonardo De Sa; Aimé Druilhet; Frédérique Said

1991-02-01T23:59:59.000Z

291

Open-Channel Flow and Turbulence Measurement by High-Resolution Doppler Sonar  

Science Conference Proceedings (OSTI)

Measurements of water velocity and turbulence in a water flume using a Doppler sonar operating at 1 MHz are presented. Analysis of the results shows that the instrument qualifies as a very useful tool for nonintrusive and accurate measurement of ...

R. Lhermitte; U. Lemmin

1994-10-01T23:59:59.000Z

292

Doppler Lidar Measurements of Turbulent Structure Function over an Urban Area  

Science Conference Proceedings (OSTI)

Analysis of radial wind velocity data from the Salford pulsed Doppler infrared lidar is used to calculate turbulent spectral statistics over the city of Salford in the United Kingdom. The results presented here, first, outline the error ...

F. Davies; C. G. Collier; G. N. Pearson; K. E. Bozier

2004-05-01T23:59:59.000Z

293

The Turbulence Structure in a Continental Stratocumulus Cloud from Millimeter-Wavelength Radar Observations  

Science Conference Proceedings (OSTI)

The turbulent-scale vertical velocity structure in a continental stratocumulus cloud is studied using a 3-mm wavelength Doppler radar operating in a vertically pointing mode. The radar observations provided 30-m sampling in the vertical with 2-s ...

Pavlos Kollias; Bruce Albrecht

2000-08-01T23:59:59.000Z

294

Transducer-Shadow Effects on Turbulence Spectra Measured by Sonic Anemometers  

Science Conference Proceedings (OSTI)

We show that the horizontal turbulent velocity components measured by the common sonic anemometer array can suffer attenuation and crosstalk as a result of the flow blockage caused by the acoustic transducer assemblies. Using an analytical model ...

John C. Wyngaard; Shi-Feng Zhang

1985-12-01T23:59:59.000Z

295

A Wind Tunnel Study of Turbulence Effects on the Scavenging of Aerosol Particles by Water Drops  

Science Conference Proceedings (OSTI)

Laboratory experiments are described where the effects of turbulence on the impaction scavenging of aerosol particles by water drops were investigated. During the experiments the drops were freely suspended at their terminal velocities in the ...

O. Vohl; S. K. Mitra; K. Diehl; G. Huber; S. C. Wurzler; K-L. Kratz; H. R. Pruppacher

2001-10-01T23:59:59.000Z

296

Measurements of Turbulence at Two Tidal Energy Sites in Puget Sound, WA  

SciTech Connect

Field measurements of turbulence are pre- sented from two sites in Puget Sound, WA (USA) that are proposed for electrical power generation using tidal current turbines. Rapidly sampled data from multiple acoustic Doppler instruments are analyzed to obtain statistical mea- sures of fluctuations in both the magnitude and direction of the tidal currents. The resulting turbulence intensities (i.e., the turbulent velocity fluctuations normalized by the harmonic tidal currents) are typically 10% at the hub- heights (i.e., the relevant depth bin) of the proposed turbines. Length and time scales of the turbulence are also analyzed. Large-scale, anisotropic eddies dominate the energy spectra, which may be the result of proximity to headlands at each site. At small scales, an isotropic turbulent cascade is observed and used to estimate the dissipation rate of turbulent kinetic energy. Data quality and sampling parameters are discussed, with an emphasis on the removal of Doppler noise from turbulence statistics.

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

2012-06-05T23:59:59.000Z

297

Chemical turbulence equivalent to Nikolavskii turbulence  

E-Print Network (OSTI)

We find evidence that a certain class of reaction-diffusion systems can exhibit chemical turbulence equivalent to Nikolaevskii turbulence. The distinctive characteristic of this type of turbulence is that it results from the interaction of weakly stable long-wavelength modes and unstable short-wavelength modes. We indirectly study this class of reaction-diffusion systems by considering an extended complex Ginzburg-Landau (CGL) equation that was previously derived from this class of reaction-diffusion systems. First, we show numerically that the power spectrum of this CGL equation in a particular regime is qualitatively quite similar to that of the Nikolaevskii equation. Then, we demonstrate that the Nikolaevskii equation can in fact be obtained from this CGL equation through a phase reduction procedure applied in the neighborhood of a codimension-two Turing--Benjamin-Feir point.

Dan Tanaka

2004-03-09T23:59:59.000Z

298

Experimental Study of Current-Driven Turbulence During Magnetic Reconnection  

SciTech Connect

CMPD Final Report Experimental Study of Current-Driven Turbulence During Magnetic Reconnection Miklos Porkolab, PI, Jan Egedal, co-PI, William Fox, graduate student. This is the final report for Grant DE-FC02-04ER54786, �¢����MIT Participation in the Center for Multiscale Plasma Dynamics,�¢��� which was active from 8/1/2004 to 7/31/2010. This Grant supported the thesis work of one MIT graduate student, William Fox, The thesis research consisted of an experimental study of the fluctuations arising during magnetic reconnection in plasmas on the Versatile Toroidal Facility (VTF) at MIT Plasma Science and Fusion Center (PSFC). The thesis was submitted and accepted by the MIT physics Department, �¢����W. Fox, Experimental Study of Current-Driven Turbulence During Magnetic Reconnection, Ph.D. Thesis, MIT (2009)�¢���. In the VTF experiment reconnection and current-sheet formation is driven by quickly changing currents in a specially arranged set of internal conductors. Previous work on this device [Egedal, et al, PRL 98, 015003, (2007)] identified a �¢����spontaneous�¢��� reconnection regime. In this work fluctuations were studied using impedance-matched, high-bandwidth Langmuir probes. Strong, broadband fluctuations, with frequencies extending from near the lower-hybrid frequency [fLH = (fcefci)1/2] to the electron cyclotron frequency fce were found to arise during the reconnection events. Based on frequency and wavelength measurements, lower-hybrid waves and Trivelpiece-Gould waves were identified. The lower-hybrid waves are easiest to drive with strong perpendicular drifts or gradients which arise due to the reconnection events; an appealing possibility is strong temperature gradients. The Trivelpiece-Gould modes can result from kinetic, bump-on-tail instability of a runaway electron population energized by the reconnection events. We also observed that the turbulence is often spiky, consisting of discrete positive-potential spikes, which were identified as �¢����electron phase-space holes,�¢��� a class of nonlinear solitary wave known to evolve from a strong beam-on-tail instability. We established that fast electrons were produced by magnetic reconnection. Overall, these instabilities were found to be a consequence of reconnection, specifically the strong energization of electrons, leading to steep gradients in both coordinate- and velocity-space. Estimates (using quasi-linear theory) of the anomalous resistivity due to these modes did not appear large enough to substantially impact the reconnection process. Relevant publications: �¢���¢ W. Fox, M. Porkolab, et al, Phys. Rev. Lett. 101, 255003 (2008). �¢���¢ W. Fox, M. Porkolab, et al, Phys. Plasmas 17, 072303, (2010).

Miklos Porkolab; Jan Egedal-Pedersen; William Fox

2010-08-31T23:59:59.000Z

299

Petascale Simulations of Inhomogeneous AlfvĂ©n Turbulence in the Solar Wind  

NLE Websites -- All DOE Office Websites (Extended Search)

A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii A snapshot of turbulent magnetic field lines (red) inside a coronal hole that expands from a small patch on the solar surface to 5 solar radii. Alfven waves (AW), launched by convective motions on the photosphere, propagate in the inhomogeneous Solar atmosphere producing primary reflected waves that interact non-linearly with the outward waves, driving a turbulent cascade. This cascade continues with secondary reflections in a very complex interplay between wave reflections and nonlinear interactions. Selected slices across the simulation domain show contours of plasma current, indicating the generation of small scale structures where the

300

MU Radar and Lidar Observations of Clear-Air Turbulence underneath Cirrus  

Science Conference Proceedings (OSTI)

Turbulence generation mechanisms prevalent in the atmosphere are mainly shear instabilities, breaking of internal buoyancy waves, and convective instabilities such as thermal convection due to heating of the ground. In the present work, clear-air ...

Hubert Luce; Takuji Nakamura; Masayuki K. Yamamoto; Mamoru Yamamoto; Shoichiro Fukao

2010-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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 Langmuir Turbulence in Pure Wind Seas  

Science Conference Proceedings (OSTI)

The scaling of turbulent kinetic energy (TKE) and its vertical component (VKE) in the upper ocean boundary layer, forced by realistic wind stress and surface waves including the effects of Langmuir circulations, is investigated using large-eddy ...

Ramsey R. Harcourt; Eric A. D’Asaro

2008-07-01T23:59:59.000Z

302

A KINETIC MODEL OF SOLAR WIND GENERATION BY OBLIQUE ION-CYCLOTRON WAVES  

Science Conference Proceedings (OSTI)

The fast solar wind is generated by extended perpendicular ion heating in coronal holes, but the kinetic mechanism responsible for this heating has not been determined. One long-standing possibility is the resonant-cyclotron dissipation of ion-cyclotron waves, replenished from a turbulent cascade of interacting counter-propagating Alfven waves. We present results of a kinetic model for proton heating by the quasilinear resonant-cyclotron wave-particle interaction in a coronal hole. The resonant wave spectrum is taken as a power law in wavenumber, uniformly distributed in propagation direction between 0 deg. and 60 deg. with respect to the large-scale radial magnetic field. We obtain the steady-state solution of the kinetic guiding-center equation for the proton distribution in an expanding coronal hole, including the effects of large-scale forces of gravity, charge-separation electric field, Alfven wave ponderomotive force, and mirror force, along with the small-scale scattering from the wave dissipation. We find that plausible wave intensities can yield reasonable flow speeds and temperatures in the heliocentric radial range between 2 and 6 solar radii. We address the claim in earlier work that dissipation of parallel-propagating ion-cyclotron waves cannot provide enough acceleration and show that claim to be incorrect. We find that the combined action of the large-scale forces and the resonant-cyclotron scattering produces proton distribution functions with a characteristic structure: compressed in the sunward half of velocity space with a high-density shell separate from the origin, and relatively expanded in the anti-sunward half of velocity space. We suggest that qualitatively similar proton distributions would result from the kinetic evolution of any sufficiently effective perpendicular heating mechanism operating in an expanding coronal hole.

Isenberg, Philip A.; Vasquez, Bernard J. [Institute for the Study of Earth, Oceans and Space and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)

2011-04-20T23:59:59.000Z

303

Dissipation and Heating in Supersonic Hydrodynamic and MHD Turbulence  

E-Print Network (OSTI)

We study energy dissipation and heating by supersonic MHD turbulence in molecular clouds using Athena, a new higher-order Godunov code. We analyze the dependence of the saturation amplitude, energy dissipation characteristics, power spectra, sonic scaling, and indicators of intermittency in the turbulence on factors such as the magnetic field strength, driving scale, energy injection rate, and numerical resolution. While convergence in the energies is reached at moderate resolutions, we find that the power spectra require much higher resolutions that are difficult to obtain. In a 1024^3 hydro run, we find a power law relationship between the velocity dispersion and the spatial scale on which it is measured, while for an MHD run at the same resolution we find no such power law. The time-variability and temperature intermittency in the turbulence both show a dependence on the driving scale, indicating that numerically driving turbulence by an arbitrary mechanism may not allow a realistic representation of these...

Lemaster, M Nicole

2008-01-01T23:59:59.000Z

304

Inertial range turbulence in kinetic plasmas  

E-Print Network (OSTI)

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

Howes, G G

2007-01-01T23:59:59.000Z

305

Inertial range turbulence in kinetic plasmas  

E-Print Network (OSTI)

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

G. G. Howes

2007-11-27T23:59:59.000Z

306

Charecterization of inertial and pressure effects in homogeneous turbulence  

E-Print Network (OSTI)

The objective of the thesis is to characterize the linear and nonlinear aspects of inertial and pressure effects in turbulent flows. In the first part of the study, computations of Navier-Stokes and 3D Burgers equations are performed in the rapid distortion (RD) limit to analyze the inviscid linear processes in homogeneous turbulence. By contrasting the results of Navier- Stokes RD equations and Burgers RD equations, the effect of pressure can be isolated. The evolution of turbulent kinetic energy and anisotropy components and invariants are examined. In the second part of the thesis, the velocity gradient dynamics in turbulent flows are studied with the help of inviscid 3D Burgers equations and restricted Euler equations. The analytical asymptotic solutions of velocity gradient tensor are obtained for both Burgers and restricted Euler equations. Numerical computations are also performed to identify the stable solutions. The results are compared and contrasted to identify the effect of pressure on nonlinear velocity gradient dynamics. Of particular interest are the sign of the intermediate principle strain-rate and tendency of vorticity to align with the intermediate principle strain-rate. These aspects of velocity gradients provide valuable insight into the role of pressure in the energy cascade process.

Bikkani, Ravi Kiran

2005-08-01T23:59:59.000Z

307

Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast uncertainty  

E-Print Network (OSTI)

Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast, the uncertainty of the forecast FTLE fields is analyzed using ensemble forecasting. Unavoidable errors of the forecast velocity data due to the chaotic dynamics of the atmosphere is the salient reason for errors

Ross, Shane

308

The first turbulent combustion  

E-Print Network (OSTI)

The first turbulent combustion arises in a hot big bang cosmological model Gibson (2004) where nonlinear exothermic turbulence permitted by quantum mechanics, general relativity, multidimensional superstring theory, and fluid mechanics cascades from Planck to strong force freeze out scales with gravity balancing turbulent inertial-vortex forces. Interactions between Planck scale spinning and non-spinning black holes produce high Reynolds number turbulence and temperature mixing with huge Reynolds stresses driving the rapid inflation of space. Kolmogorovian turbulent temperature patterns are fossilized as strong-force exponential inflation stretches them beyond the scale of causal connection ct where c is light speed and t is time. Fossil temperature turbulence patterns seed nucleosynthesis, and then hydro-gravitational structure formation in the plasma epoch, Gibson (1996, 2000). Evidence about formation mechanisms is preserved by cosmic microwave background temperature anisotropies. CMB spectra indicate hydro-gravitational fragmentation at supercluster to galaxy masses in the primordial plasma with space stretched by \\~10^50. Bershadskii and Sreenivasan (2002, 2003) CMB multi-scaling coefficients support a strong turbulence origin for the anisotropies prior to the plasma epoch.

Carl H. Gibson

2005-01-19T23:59:59.000Z

309

Interactions between Rain and Wind Waves  

Science Conference Proceedings (OSTI)

Effects of rain on surface waves have been investigated in a circulating wind-wave tank. Surface displacement and slope spectra under different wind velocities were measured near the upwind and downwind edges of a region with simulated rains. ...

Ying-Keung Poon; Shih Tang; Jin Wu

1992-09-01T23:59:59.000Z

310

Inertia–Gravity Waves in the Stratosphere  

Science Conference Proceedings (OSTI)

The propagation and refraction of stationary inertia–gravity waves in the winter stratosphere is examined with ray tracing. Due to their smaller vertical group velocity these waves experience more lateral ray movement and horizontal refraction ...

Timothy J. Dunkerton

1984-12-01T23:59:59.000Z

311

Random walk of magnetic field lines in dynamical turbulence: A field line tracing method. I. Slab turbulence  

SciTech Connect

To study the wandering of magnetic field lines is an important subject in theoretical physics. Results of field line random walk theories can be applied in plasma physics as well as astrophysics. Previous investigations are based on magnetostatic models. These models have been used in analytical work as well as in computer simulations to warrant mathematical and numerical tractability. To replace the magnetostatic model by a dynamical turbulence model is a difficult task. In the present article, a field line tracing method is used to describe field line wandering in dynamical magnetic turbulence. As examples different models are employed, namely, the plasma wave model, the damping model of dynamical turbulence, and the random sweeping model. It is demonstrated that the choice of the turbulence model has a very strong influence on the field line structure. It seems that if dynamical turbulence effects are included, Markovian diffusion can be found for other forms of the wave spectrum as in the magnetostatic model. Therefore, the results of the present paper are useful to specify turbulence models. As a further application we consider charged particle transport at early times.

Shalchi, A. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2010-08-15T23:59:59.000Z

312

Effects of wind shear and turbulence on wind turbine power curves  

DOE Green Energy (OSTI)

It is a common practice to use wind speeds at hub height in determining wind turbine power curves. Although the possible influence of other variables (sub as turbulence and wind shear) is generally neglected in power curve measurements, we discovered the importance of other variables in an analysis of power curves for three 2.5 MW wind turbines. When the power curves were stratified by turbulence intensity. Such a large sensitivity to turbulence was not expected, and further analyses were conducted to determine if other factors accompanying the change in turbulence level could cause or contribute to the observed sensitivity of the power curves to turbulence. In summary, the sensitivity of the observed power curves was largely due to two factors: (1) an actual sensitivity to turbulence in determining the power curve and (2) the deviation of the disk-averaged velocity from the hub-height velocity under low turbulence conditions that were most prevalent at the site. An examination of the wind shear profiles over the height of the rotor disk revealed that low turbulence conditions were characterized by strong shear in the lower half of the rotor disk and weak or negative shear in the upper half. Implications of this analysis are that significant errors in power curve measurements can result if the effects of wind shear and turbulence are ignored. 7 refs., 6 figs.

Elliott, D.L. (Pacific Northwest Lab., Richland, WA (USA)); Cadogan, J.B. (USDOE, Washington, DC (USA))

1990-09-01T23:59:59.000Z

313

Processing of turbulence-layer wind speed with Generalized SCIDAR through wavelet analysis  

E-Print Network (OSTI)

We describe a new method involving wavelet transforms for deriving the wind velocity associated with atmospheric turbulence layers from Generalized SCIDAR measurements. The algorithm analyses the cross-correlation of a series of scintillation patterns separated by lapses of Dt, 2Dt, 3Dt, 4Dt and 5Dt using wavelet transforms. Wavelet analysis provides the position, direction and altitude of the different turbulence layers detected in each cross-correlation. The comparison and consistency of the turbulent layer displacements in consecutive cross-correlations allow the determination of their velocities and avoid misidentifications associated with noise and/or overlapping layers. To validate the algorithm, we have compared the velocity of turbulence layers derived on four nights with the wind vertical profile provided by balloon measurements. The software is fully automated and is able to analyse huge amounts of Generalized SCIDAR measurements.

B. Garcia-Lorenzo; J. J. Fuensalida

2006-08-28T23:59:59.000Z

314

Generation of residual energy in the turbulent solar wind  

SciTech Connect

In situ observations of the fluctuating solar wind flow show that the energy of magnetic field fluctuations always exceeds that of the kinetic energy, and therefore the difference between the kinetic and magnetic energies, known as the residual energy, is always negative. The same behaviour is found in numerical simulations of magnetohydrodynamic turbulence. We study the dynamics of the residual energy for strong, anisotropic, critically balanced magnetohydrodynamic turbulence using the eddy damped quasi-normal Markovian approximation. Our analysis shows that for stationary critically balanced magnetohydrodynamic turbulence, negative residual energy will always be generated by nonlinear interacting Alfven waves. This offers a general explanation for the observation of negative residual energy in solar wind turbulence and in the numerical simulations.

Gogoberidze, G. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Institute of Theoretical Physics, Ilia State University, 3/5 Cholokashvili Ave., 0162 Tbilisi (Georgia); Chapman, S. C.; Hnat, B. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2012-10-15T23:59:59.000Z

315

Nonlinear Flow Generation By Electrostatic Turbulence In Tokamaks  

SciTech Connect

Global gyrokinetic simulations have revealed an important nonlinear flow generation process due to the residual stress produced by electrostatic turbulence of ion temperature gradient (ITG) modes and trapped electron modes (TEM). In collisionless TEM (CTEM) turbulence, nonlinear residual stress generation by both the fluctuation intensity and the intensity gradient in the presence of broken symmetry in the parallel wave number spectrum is identified for the first time. Concerning the origin of the symmetry breaking, turbulence self-generated low frequency zonal flow shear has been identified to be a key, universal mechanism in various turbulence regimes. Simulations reported here also indicate the existence of other mechanisms beyond E × B shear. The ITG turbulence driven “intrinsic” torque associated with residual stress is shown to increase close to linearly with the ion temperature gradient, in qualitative agreement with experimental observations in various devices. In CTEM dominated regimes, a net toroidal rotation is driven in the cocurrent direction by “intrinsic” torque, consistent with the experimental trend of observed intrinsic rotation. The finding of a “flow pinch” in CTEM turbulence may offer an interesting new insight into the underlying dynamics governing the radial penetration of modulated flows in perturbation experiments. Finally, simulations also reveal highly distinct phase space structures between CTEM and ITG turbulence driven momentum, energy and particle fluxes, elucidating the roles of resonant and non-resonant particles.

W.X. Wang, P.H. Diamond, T.S. Hahm, S. Ethier, G. Rewoldt, and W.M. Tang

2010-07-07T23:59:59.000Z

316

Observations of Edge Turbulence  

NLE Websites -- All DOE Office Websites (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

317

Model-based design of transverse wall oscillations for turbulent drag reduction  

E-Print Network (OSTI)

Over the last two decades, both experiments and simulations have demonstrated that transverse wall oscillations with properly selected amplitude and frequency can reduce turbulent drag by as much as 40%. In this paper, we develop a model-based approach for designing oscillations that suppress turbulence in a channel flow. We utilize eddy-viscosity-enhanced linearization of the turbulent flow with control in conjunction with turbulence modeling to determine skin-friction drag in a simulation-free manner. The Boussinesq eddy viscosity hypothesis is used to quantify the effect of fluctuations on the mean velocity in the flow subject to control. In contrast to the traditional approach that relies on numerical simulations, we determine the turbulent viscosity from the second order statistics of the linearized model driven by white-in-time stochastic forcing. The spatial power spectrum of the forcing is selected to ensure that the linearized model for the uncontrolled flow reproduces the turbulent energy spectrum. ...

Moarref, Rashad

2012-01-01T23:59:59.000Z

318

Numerical simulations to study solar wind turbulence  

Science Conference Proceedings (OSTI)

Numerical simulation of coupled equations of kinetic Alfven wave (KAW) and ion acoustic wave is presented in the solar wind. The nonlinear dynamical equations satisfy the modified Zakharov system of equations by taking the nonadiabatic response of the background density. The ponderomotive nonlinearity is incorporated in the wave dynamics. The effect of Landau damping of KAW is taken into account. Localization of magnetic field intensity and the wavenumber spectra (perpendicular and parallel) of magnetic fluctuations are studied in solar plasmas around 1 a.u. Our results reveal the formation of damped localized structures and the steeper spectra that are in good agreement with the observations. These damped structures and steeper turbulent spectra can be responsible for plasma heating and particle acceleration in solar wind.

Sharma, R. P.; Sharma, Nidhi; Kumar, Sanjay [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Kumar, Sachin [Department of Applied Sciences and Humanities, Ajay Kumar Garg Engineering College, Ghaziabad 201009 (India); Singh, H. D. [Department of Physical Sciences, School of Physical and Chemical Sciences, Sikkim University, Sikkim 737102 (India)

2011-02-15T23:59:59.000Z

319

The Influence of Stratification and Nonlocal Turbulent Production on Estuarine Turbulence: An Assessment of Turbulence Closure with Field Observations  

Science Conference Proceedings (OSTI)

Field observations of turbulent kinetic energy (TKE), dissipation rate ?, and turbulent length scale demonstrate the impact of both density stratification and nonlocal turbulent production on turbulent momentum flux. The data were collected in a ...

Malcolm E. Scully; W. Rocky Geyer; John H. Trowbridge

2011-01-01T23:59:59.000Z

320

Modeling wind forcing in phase resolving simulation of nonlinear wind waves  

E-Print Network (OSTI)

Wind waves in the ocean are a product of complex interaction of turbulent air flow with gravity driven water surface. The coupling is strong and the waves are non-stationary, irregular and highly nonlinear, which restricts ...

Kalmikov, Alexander G

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


321

Aircraft Observation of Convection Waves over Southern Germany—A Case Study  

Science Conference Proceedings (OSTI)

A vertical cross section of 100 km × 10 km through a daytime midlatitude troposphere is analyzed using aircraft turbulence data with 1.5-m spatial resolution. Convectively forced internal gravity waves, also referred to as “convection waves,” ...

Thomas Hauf

1993-12-01T23:59:59.000Z

322

Laser Doppler Velocimeter particle velocity measurement system  

DOE Green Energy (OSTI)

This report gives a detailed description of the operation of the Laser Doppler Velocimeter (LDV) system maintained by DIAL at MSU. LDV is used for the measurement of flow velocities and turbulence levels in various fluid flow settings. Ills report details the operation and maintenance of the LDV system and provides a first-time user with pertinent information regarding the system`s setup for a particular application. Particular attention has been given to the use of the Doppler signal analyzer (DSA) and the burst spectrum analyzer (BSA) signal processors and data analysis.

Wilson, W.W.; Srikantaiah, D.V.; Philip, T.; George, A.

1993-10-01T23:59:59.000Z

323

Noise Effects on Wave-Generated Transport Induced by Ideal Waves  

Science Conference Proceedings (OSTI)

The authors consider the transport velocity in boundary layer flows driven by either noisy monochromatic progressive or standing waves. The central issue addressed here is whether such flows are capable of sustaining a transport velocity when ...

Juan M. Restrepo; Gary K. Leaf

2002-08-01T23:59:59.000Z

324

Astrophysical gyrokinetics: kinetic and fluid turbulent cascades in magnetized weakly collisional plasmas  

E-Print Network (OSTI)

We present a theoretical framework for plasma turbulence in astrophysical plasmas (solar wind, interstellar medium, galaxy clusters, accretion disks). The key assumptions are that the turbulence is anisotropic with respect to the mean magnetic field and frequencies are low compared to the ion cyclotron frequency. The energy injected at the outer scale scale has to be converted into heat, which ultimately cannot be done without collisions. A KINETIC CASCADE develops that brings the energy to collisional scales both in space and velocity. Its nature depends on the physics of plasma fluctuations. In each of the physically distinct scale ranges, the kinetic problem is systematically reduced to a more tractable set of equations. In the "inertial range" above the ion gyroscale, the kinetic cascade splits into a cascade of Alfvenic fluctuations, which are governed by the RMHD equations at both the collisional and collisionless scales, and a passive cascade of compressive fluctuations, which obey a linear kinetic equation along the moving field lines associated with the Alfvenic component. In the "dissipation range" between the ion and electron gyroscales, there are again two cascades: the kinetic-Alfven-wave (KAW) cascade governed by two fluid-like Electron RMHD equations and a passive phase-space cascade of ion entropy fluctuations. The latter cascade brings the energy of the inertial-range fluctuations that was damped by collisionless wave-particle interaction at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAW energy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for these cascades. Astrophysical and space-physical applications are discussed in detail.

A. A. Schekochihin; S. C. Cowley; W. Dorland; G. W. Hammett; G. G. Howes; E. Quataert; T. Tatsuno

2007-03-31T23:59:59.000Z

325

Composite Vertical Structure of Vertical Velocity in Nonprecipitating Cumulus Clouds  

Science Conference Proceedings (OSTI)

Vertical transects of Doppler vertical velocity data, obtained from an airborne profiling millimeter-wave cloud radar, are composited for a large number of cumulus clouds (Cu) at various stages of their life cycle, to examine typical circulations ...

Yonggang Wang; Bart Geerts

2013-05-01T23:59:59.000Z

326

Sheets Wave Basin | Open Energy Information  

Open Energy Info (EERE)

Sheets Wave Basin Sheets Wave Basin Jump to: navigation, search Basic Specifications Facility Name Sheets Wave Basin Overseeing Organization University of Rhode Island Hydrodynamic Testing Facility Type Wave Basin Length(m) 30.0 Beam(m) 3.6 Depth(m) 1.8 Cost(per day) $750(+ Labor/Materials) Towing Capabilities Towing Capabilities Yes Maximum Velocity(m/s) 2.0 Length of Effective Tow(m) 25.0 Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.3 Maximum Wave Height(m) at Wave Period(s) 3.0 Maximum Wave Length(m) 10 Wave Period Range(s) 3.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Pre-programmed for regular and irregular waves, but wavemaker is capable of any input motion. Wave Direction Uni-Directional

327

An Airborne and Wind Tunnel Evaluation of a Wind Turbulence Measurement System for Aircraft-Based Flux Measurements  

Science Conference Proceedings (OSTI)

Although the ability to measure vertical eddy fluxes of gases from aircraft platforms represents an important capability to obtain spatially resolved data, accurate and reliable determination of the turbulent vertical velocity presents a great ...

K. E. Garman; K. A. Hill; P. Wyss; M. Carlsen; J. R. Zimmerman; B. H. Stirm; T. Q. Carney; R. Santini; P. B. Shepson

2006-12-01T23:59:59.000Z

328

Turbulence Structure of the Convective Boundary Layer. Part II. Phonenix 78 Aircraft Observations of Thermals and Their Environment  

Science Conference Proceedings (OSTI)

A conditional sampling technique based upon the mixed layer spectra of vertical velocity and temperature is developed. This technique is used to analyze the turbulence data obtained by aircraft during the Phoenix 78 convective boundary layer ...

George S. Young

1988-02-01T23:59:59.000Z

329

Analysis of Turbulence Structure in the Surface Layer with a Modified Similarity Formulation for Near Neutral Conditions  

Science Conference Proceedings (OSTI)

Data from a recent detailed surface layer experiment are critically examined in terms of the turbulent kinetic energy budget and the other second order moment budgets formed by the three velocity components and temperature. In moderately unstable ...

Ulf Högström

1990-08-01T23:59:59.000Z

330

Turbulent Vertical Kinetic Energy in the Ocean Mixed Layer  

Science Conference Proceedings (OSTI)

Vertical velocities in the ocean boundary layer were measured for two weeks at an open ocean, wintertime site using neutrally buoyant floats. Simultaneous measurements of the surface meteorology and surface waves showed a large variability in ...

Eric A. D'Asaro

2001-12-01T23:59:59.000Z

331

The Coupling of Vertical Velocity and Signal Power Observed with the SOUSY VHF Radar  

Science Conference Proceedings (OSTI)

The perturbations to the static stability (and hence to the radar reflectivity) and to the velocity in a vertically propagating gravity wave are correlated, and the sign of the correlation depends on whether the wave is propagating upward or ...

G. D. Nastrom; R. Rüster; G. Schmidt

1998-01-01T23:59:59.000Z

332

Traveling-wave photodetector  

DOE Patents (OSTI)

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size. 4 figures.

Hietala, V.M.; Vawter, G.A.

1993-12-14T23:59:59.000Z

333

Traveling-wave photodetector  

DOE Patents (OSTI)

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size.

Hietala, V.M.; Vawter, G.A.

1992-12-31T23:59:59.000Z

334

Traveling-wave photodetector  

DOE Patents (OSTI)

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size.

Hietala, Vincent M. (Placitas, NM); Vawter, Gregory A. (Albuquerque, NM)

1993-01-01T23:59:59.000Z

335

Baroclinic Waves with Parameterized Effects of Moisture Interpreted Using Rossby Wave Components  

Science Conference Proceedings (OSTI)

A theoretical framework is developed for the evolution of baroclinic waves with latent heat release parameterized in terms of vertical velocity. Both wave–conditional instability of the second kind (CISK) and large-scale rain approaches are ...

Hylke de Vries; John Methven; Thomas H. A. Frame; Brian J. Hoskins

2010-09-01T23:59:59.000Z

336

Turbulence transmission in parallel modified shocks using ray tracing  

E-Print Network (OSTI)

We apply a semi-classical approach of handling waves as quasiparticle gas in a slowly varying flow -- analogous to ray tracing -- to calculate the Alfven wave transmission parameters, the resulting cross-helicity of the waves and the scattering-centre compression ratio, for cases where the shock thickness is large enough for the turbulent waves in the plasma to see the transition of the background flow parameters as smooth and slowly varying. For nonrelativistic shocks the wave transmission produces similar effects on the downstream turbulence and the scattering-centre compression ratio as does the transmission through a step shock: the downstream Alfven waves propagate predominantly towards the shock in the local plasma frame and, thus, the scattering-centre compression ratio is larger than the gas compression ratio. For thick relativistic shocks, however, we find qualitative differences with respect to the step-shock case: for low-Alfvenic-Mach-number shocks the downstream waves propagate predominantly away from the shock, and the scattering-centre compression ratio is lower than that of the gas. Thus, when taken into account, the Alfven wave transmission can decrease the efficiency of the first-order Fermi acceleration in a thick relativistic shock.

Joni Tammi; Rami Vainio

2006-09-14T23:59:59.000Z

337

Turbulent thermal diffusion of aerosols in geophysics and laboratory experiments  

E-Print Network (OSTI)

We discuss a new phenomenon of turbulent thermal diffusion associated with turbulent transport of aerosols in the atmosphere and in laboratory experiments. The essence of this phenomenon is the appearance of a nondiffusive mean flux of particles in the direction of the mean heat flux, which results in the formation of large-scale inhomogeneities in the spatial distribution of aerosols that accumulate in regions of minimum mean temperature of the surrounding fluid. This effect of turbulent thermal diffusion was detected experimentally. In experiments turbulence was generated by two oscillating grids in two directions of the imposed vertical mean temperature gradient. We used Particle Image Velocimetry to determine the turbulent velocity field, and an Image Processing Technique based on an analysis of the intensity of Mie scattering to determine the spatial distribution of aerosols. Analysis of the intensity of laser light Mie scattering by aerosols showed that aerosols accumulate in the vicinity of the minimum mean temperature due to the effect of turbulent thermal diffusion. Geophysical applications of the obtained results are discussed.

A. Eidelman; T. Elperin; N. Kleeorin; A. Krein; I. Rogachevskii; J. Buchholz; G. Gruenefeld

2004-11-11T23:59:59.000Z

338

The evaluation of a turbulent loads characterization system  

DOE Green Energy (OSTI)

In this paper we discuss an on-line turbulent load characterization system that has been designed to acquire loading spectra from turbines of the same design operating in several different environments and from different turbine designs operating in the same environment. This System simultaneously measures the rainflow-counted alternating and mean loading spectra and the hub-height turbulent mean shearing stress and atmospheric stability associated with the turbulent inflow. We discuss the theory behind the measurement configuration and the results of proof-of-concept testing recently performed at the National Wind Technology Center (NWTC) using a Bergey EXCEL-S 10-kW wind turbine. The on-line approach to characterizing the load spectra and the inflow turbulent scaling parameter produces results that are consistent with other measurements. The on-line approximation of the turbulent shear stress or friction velocity u* also is considered adequate. The system can be used to characterize turbulence loads during turbine deployment in a wide variety of environments. Using the WISPER protocol, we found that a wide-range, variable-speed turbine will accumulate a larger number of stress cycles in the low-cycle, high-amplitude (LCHA) region when compared with a constant speed rotor under similar inflow conditions.

Kelley, N.D.; McKenna, H.E. [National Renewable Energy Lab., Golden, CO (United States)

1996-01-01T23:59:59.000Z

339

A Theory of Baroclinic Turbulence  

Science Conference Proceedings (OSTI)

Understanding the physical mechanism maintaining fluid turbulence remains a fundamental theoretical problem. The two-layer model is an analytically and computationally simple system in which the dynamics of turbulence can be conveniently studied; ...

Brian F. Farrell; Petros J. Ioannou

2009-08-01T23:59:59.000Z

340

Statistical Predictability of Decaying Turbulence  

Science Conference Proceedings (OSTI)

We use statistical models of turbulence with “eddy damping” (EDQNM) in order to study the problem of predictability of freely evolving two- and three-dimensional isotropic turbulent flows.

Olivier Métais; Marcel Lesieur

1986-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Supersaturation Intermittency in Turbulent Clouds  

Science Conference Proceedings (OSTI)

It is hypothesized that bursts of high supersaturation are produced in turbulent, convective clouds through interactions between cloud droplets and the small-scale structure of atmospheric turbulence. This hypothesis is based on the observation ...

Raymond A. Shaw

2000-10-01T23:59:59.000Z

342

The Decay of Convective Turbulence  

Science Conference Proceedings (OSTI)

Using simulations with a large-eddy model we have studied the decay of convective turbulence in the atmospheric boundary layer when the upward surface sensible heat flux is suddenly stopped. The decay of turbulent kinetic energy and temperature ...

F. T. M. Nieuwstadt; R. A. Brost

1986-03-01T23:59:59.000Z

343

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

344

A Model for Vortex-Trapped Internal Waves  

Science Conference Proceedings (OSTI)

Regions of negative vorticity are observed to trap and amplify near-inertial internal waves, which are sources of turbulent mixing 10–100 times higher than typically found in the stratified ocean interior. Because these regions are of finite ...

Eric Kunze; Emmanuel Boss

1998-10-01T23:59:59.000Z

345

Secondary Instabilities in Breaking Inertia–Gravity Waves  

Science Conference Proceedings (OSTI)

The three-dimensionalization of turbulence in the breaking of nearly vertically propagating inertia–gravity waves is investigated numerically using singular vector analysis applied to the Boussinesq equations linearized about three two-dimensional ...

Mark D. Fruman; Ulrich Achatz

2012-01-01T23:59:59.000Z

346

Oceanic Isopycnal Slope Spectra. Part I: Internal Waves  

Science Conference Proceedings (OSTI)

Horizontal tow measurements of internal waves are rare and have been largely supplanted in recent decades by vertical profile measurements. Here, estimates of isotherm displacements and turbulence dissipation rate from a towed vehicle deployed ...

Jody M. Klymak; James N. Moum

2007-05-01T23:59:59.000Z

347

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

E-Print Network (OSTI)

Turbulent flows and coherent structures emerging within turbulent flow fields have been extensively studied for the past few decades and a wide variety of experimental and numerical techniques have been developed for measurement and analysis of turbulent flows. The complex nature of turbulence requires methods that can accurately estimate its highly chaotic spatial and temporal behavior. Some of the classical cases of turbulent flows with simpler geometries have been well characterized by means of the existing experimental techniques and numerical models. Nevertheless, since most turbulent fields are of complex geometries; there is an increasing interest in the study of turbulent flows through models with more complicated geometries. In this dissertation, characteristics of turbulent flows through two different facilities with complex geometries are studied applying two different experimental methods. The first study involves the investigation of turbulent impinging jets through a staggered array of rods with or without crossflow. Such flows are crucial in various engineering disciplines. This experiment aimed at modeling the coolant flow behavior and mixing phenomena within the lower plenum of a Very High Temperature Reactor (VHTR). Dynamic Particle Image Velocimetry (PIV) and Matched Index of Refraction (MIR) techniques were applied to acquire the turbulent velocity fields within the model. Some key flow features that may significantly enhance the flow mixing within the test section or actively affect some of the structural components were identified in the velocity fields. The evolution of coherent structures within the flow field is further investigated using a Snapshot Proper Orthogonal Decomposition (POD) technique. Furthermore, a comparative POD method is proposed and successfully implemented for identification of the smaller but highly influential coherent structures which may not be captured in the full-field POD analysis. The second experimental study portrays the coolant flow through the core of an annular pebble bed VHTR. The complex geometry of the core and the highly turbulent nature of the coolant flow passing through the gaps of fuel pebbles make this case quite challenging. In this experiment, a high frequency Hot Wire Anemometry (HWA) system is applied for velocity measurements and investigation of the bypass flow phenomena within the near wall gaps of the core. The velocity profiles within the gaps verify the presence of an area of increased velocity close to the outer reflector wall; however, the characteristics of the coolant flow profile is highly dependent on the gap geometry and to a less extent on the Reynolds number of the flow. The time histories of the velocity are further analyzed using a Power Spectra Density (PSD) technique to acquire information about the energy content and energy transfer between eddies of different sizes at each point within the gaps.

Amini, Noushin

2011-12-01T23:59:59.000Z

348

Fiber Optic Velocity Interferometry  

SciTech Connect

This paper explores the use of a new velocity measurement technique that has several advantages over existing techniques. It uses an optical fiber to carry coherent light to and from a moving target. A Fabry-Perot interferometer, formed by a gradient index lens and the moving target, produces fringes with a frequency proportional to the target velocity. This technique can measure velocities up to 10 km/s, is accurate, portable, and completely noninvasive.

Neyer, Barry T.

1988-04-01T23:59:59.000Z

349

Investigation of Upstream Boundary Layer Influence on Mountain Wave Breaking and Lee Wave Rotors Using a Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

Interactions between a turbulent boundary layer and nonlinear mountain waves are explored using a large-eddy simulation model. Simulations of a self-induced critical layer, which develop a stagnation layer and a strong leeside surface jet, are ...

Craig M. Smith; Eric D. Skyllingstad

2009-10-01T23:59:59.000Z

350

Fetch Relations for Wind-Generated Waves as a Function of Wind-Stress Scaling  

Science Conference Proceedings (OSTI)

We present the variation that results when fetch relations for wind-generated wave spectra are sealed by the friction velocity component in the dominant wave direction rather than the magnitude of the friction velocity, using the data collected ...

Will Perrie; Bechara Toulany

1990-11-01T23:59:59.000Z

351

Generation of acoustic-gravity waves in ionospheric HF heating experiments : simulating large-scale natural heat sources  

E-Print Network (OSTI)

In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence ...

Pradipta, Rezy

2012-01-01T23:59:59.000Z

352

Wave Dragon  

NLE Websites -- All DOE Office Websites (Extended Search)

Overtopping Wave Devices Wave Dragon ApSLtd HWETTEI - Workshop October 26-28, 2005, Washington, DC Hydrokinetic Technologies Technical and Environmental Issues Workshop the Wave...

353

Theories of convection and the spectrum of turbulence in the solar photosphere  

E-Print Network (OSTI)

Classical theories of turbulence do not describe accurately inertial range scaling laws in turbulent convection and notably fail to model the shape of the turbulent spectrum of solar photospheric convection. To understand these discrepancies, a detailed study of scale-by-scale budgets in turbulent Rayleigh-B\\'enard convection is presented, with particular emphasis placed on anisotropy and inhomogeneity. A generalized Kolmogorov equation applying to convection is derived and its various terms are computed using numerical simulations of turbulent Boussinesq convection. The analysis of the isotropic part of the equation shows that the third-order velocity structure function is significantly affected by buoyancy forcing and large-scale inhomogeneities. Anisotropic contributions to this equation are also shown to be comparable to their isotropic counterpart at moderate to large scales. Implications of these results for convection in the solar photosphere, mesogranulation and supergranulation are discussed.

F. Rincon

2006-11-28T23:59:59.000Z

354

Numerical simulation of a laboratory-scale turbulent V-flame  

SciTech Connect

We present a three-dimensional, time-dependent simulation of a laboratory-scale rod-stabilized premixed turbulent V-flame. The simulations are performed using an adaptive time-dependent low Mach number model with detailed chemical kinetics and a mixture model for differential species diffusion. The algorithm is based on a second-order projection formulation and does not require an explicit subgrid model for turbulence or turbulence chemistry interaction. Adaptive mesh refinement is used to dynamically resolve the flame and turbulent structures. Here, we briefly discuss the numerical procedure and present detailed comparisons with experimental measurements showing that the computation is able to accurately capture the basic flame morphology and associated mean velocity field. Finally, we discuss key issues that arise in performing these types of simulations and the implications of these issues for using computation to form a bridge between turbulent flame experiments and basic combustion chemistry.

Bell, J.B.; Day, M.S.; Shepherd, I.G.; Johnson, M.; Cheng, R.K.; Grcar,J.F.; Beckner, V.E.; Lijewski, M.J.

2005-02-07T23:59:59.000Z

355

RESONANCE BROADENING AND HEATING OF CHARGED PARTICLES IN MAGNETOHYDRODYNAMIC TURBULENCE  

SciTech Connect

The heating, acceleration, and pitch-angle scattering of charged particles by magnetohydrodynamic (MHD) turbulence are important in a wide range of astrophysical environments, including the solar wind, accreting black holes, and galaxy clusters. We simulate the interaction of high-gyrofrequency test particles with fully dynamical simulations of subsonic MHD turbulence, focusing on the parameter regime with {beta} {approx} 1, where {beta} is the ratio of gas to magnetic pressure. We use the simulation results to calibrate analytical expressions for test particle velocity-space diffusion coefficients and provide simple fits that can be used in other work. The test particle velocity diffusion in our simulations is due to a combination of two processes: interactions between particles and magnetic compressions in the turbulence (as in linear transit-time damping; TTD) and what we refer to as Fermi Type-B (FTB) interactions, in which charged particles moving on field lines may be thought of as beads sliding along moving wires. We show that test particle heating rates are consistent with a TTD resonance that is broadened according to a decorrelation prescription that is Gaussian in time (but inconsistent with Lorentzian broadening due to an exponential decorrelation function, a prescription widely used in the literature). TTD dominates the heating for v{sub s} >> v{sub A} (e.g., electrons), where v{sub s} is the thermal speed of species s and v{sub A} is the Alfven speed, while FTB dominates for v{sub s} << v{sub A} (e.g., minor ions). Proton heating rates for {beta} {approx} 1 are comparable to the turbulent cascade rate. Finally, we show that velocity diffusion of collisionless, large gyrofrequency particles due to large-scale MHD turbulence does not produce a power-law distribution function.

Lynn, Jacob W. [Physics Department, University of California, Berkeley, CA 94720 (United States); Parrish, Ian J.; Quataert, Eliot [Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Chandran, Benjamin D. G., E-mail: jacob.lynn@berkeley.edu [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)

2012-10-20T23:59:59.000Z

356

CURRENT SHEETS AND COLLISIONLESS DAMPING IN KINETIC PLASMA TURBULENCE  

SciTech Connect

We present the first study of the formation and dissipation of current sheets at electron scales in a wave-driven, weakly collisional, three-dimensional kinetic turbulence simulation. We investigate the relative importance of dissipation associated with collisionless damping via resonant wave-particle interactions versus dissipation in small-scale current sheets in weakly collisional plasma turbulence. Current sheets form self-consistently from the wave-driven turbulence, and their filling fraction is well correlated to the electron heating rate. However, the weakly collisional nature of the simulation necessarily implies that the current sheets are not significantly dissipated via Ohmic dissipation. Rather, collisionless damping via the Landau resonance with the electrons is sufficient to account for the measured heating as a function of scale in the simulation, without the need for significant Ohmic dissipation. This finding suggests the possibility that the dissipation of the current sheets is governed by resonant wave-particle interactions and that the locations of current sheets correspond spatially to regions of enhanced heating.

TenBarge, J. M.; Howes, G. G., E-mail: jason-tenbarge@uiowa.edu [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)

2013-07-10T23:59:59.000Z

357

Hinsdale Wave Basin 1 | Open Energy Information  

Open Energy Info (EERE)

Hinsdale Wave Basin 1 Hinsdale Wave Basin 1 Jump to: navigation, search Basic Specifications Facility Name Hinsdale Wave Basin 1 Overseeing Organization Oregon State University Hydrodynamics Hydrodynamic Testing Facility Type Wave Basin Length(m) 104.0 Beam(m) 3.7 Depth(m) 4.6 Cost(per day) $3500 Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 1.8 Maximum Wave Height(m) at Wave Period(s) 10.0 Wave Period Range(s) 10.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Monochromatic waves (cnoidal, Stokes, Airy), solitary waves, user-defined free surface timeseries or board displacement timeseries for random waves Wave Direction Uni-Directional Simulated Beach Yes Description of Beach 12' by 12' concrete slabs anchored to flume walls

358

Vorticity scaling and intermittency in drift-interchange plasma turbulence  

Science Conference Proceedings (OSTI)

The effects of spatially varying magnetic field strength on the scaling properties of plasma turbulence, modelled by an extended form of Hasegawa-Wakatani model, are investigated. We study changes in the intermittency of the velocity, density, and vorticity fields, as functions of the magnetic field inhomogeneity C=-{partial_derivative} ln B/{partial_derivative}x. While the velocity fluctuations are always self-similar and their scaling is unaffected by the value of C, the intermittency levels in density and vorticity change with parameter C, reflecting morphological changes in the coherent structures due to the interchange mechanism. Given the centrality of vorticity in conditioning plasma transport, this result is of interest in scaling the results of transport measurements and simulations in tokamak edge plasmas, where drift-interchange turbulence in the presence of a magnetic field gradient is likely to occur.

Dura, P. D.; Hnat, B.; Robinson, J.; Dendy, R. O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2012-09-15T23:59:59.000Z

359

Use of Eulerian initial conditions in a Lagrangian model of turbulent diffusion  

SciTech Connect

Simple analytic solutions were obtained for relative diffusion and meandering of puffs and plumes based upon the random-force theory of turbulent diffusion. These solutions assume that the initial velocities of the tracer particles are identical to the turbulent field velocities at the source location. The spatial and temporal correlation of these velocities are, therefore, determined by the Eulerian space-time autocorrelation function, and the appropriate ensemble averages can be calculated if this correlation function is known. These solutions exhibit many of the known features of relative diffusion and are in general agreement with similarity theory for the inertial subrange. The solutions are presented in dimensionless form and are applicable to turbulent diffusion on any scale. To apply these results to actual experiments, the magnitude of the Eulerian integral length scale L and the Eulerian and Lagrangian integral time scale t/sub E/ and t/sub L/ must be known. These can be determined only from experimental data.

Lee, J.T.; Stone, G.L.

1983-01-01T23:59:59.000Z

360

High-Velocity Rocks Final Report  

DOE Green Energy (OSTI)

The objective of our research was to develop and demonstrate seismic data-acquisition and data-processing technologies that allow geothermal prospects below high-velocity rock outcrops to be evaluated. To do this, we acquired a 3-component seismic test line across an area of exposed high-velocity rocks in Brewster County, Texas, where there is high heat flow and surface conditions mimic those found at numerous geothermal prospects. Seismic contractors have not succeeded in creating good-quality seismic data in this area for companies who have acquired data for oil and gas exploitation purposes. Our test profile traversed an area where high-velocity rocks and low-velocity sediment were exposed on the surface in alternating patterns that repeated along the test line. We verified that these surface conditions cause non-ending reverberations of Love waves, Rayleigh waves, and shallow critical refractions to travel across the earth surface between the boundaries of the fast-velocity and slow-velocity material exposed on the surface. These reverberating surface waves form the high level of noise in this area that does not allow reflections from deep interfaces to be seen and utilized. Our data-acquisition method of deploying a box array of closely spaced geophones allowed us to recognize and evaluate these surface-wave noise modes regardless of the azimuth direction to the surface anomaly that backscattered the waves and caused them to return to the test-line profile. With this knowledge of the surface-wave noise, we were able to process these test-line data to create P-P and SH-SH images that were superior to those produced by a skilled seismic data-processing contractor. Compared to the P-P data acquired along the test line, the SH-SH data provided a better detection of faults and could be used to trace these faults upward to the boundaries of exposed surface rocks. We expanded our comparison of the relative value of S-wave and P-wave seismic data for geothermal applications by inserting into this report a small part of the interpretation we have done with 3C3D data across Wister geothermal field in the Imperial Valley of California. This interpretation shows that P-SV data reveal faults (and by inference, also fractures) that cannot be easily, or confidently, seen with P-P data, and that the combination of P-P and P-SV data allows VP/VS velocity ratios to be estimated across a targeted reservoir interval to show where an interval has more sandstone (the preferred reservoir facies). The conclusion reached from this investigation is that S-wave seismic technology can be invaluable to geothermal operators. Thus we developed a strong interest in understanding the direct-S modes produced by vertical-force sources, particularly vertical vibrators, because if it can be demonstrated that direct-S modes produced by vertical-force sources can be used as effectively as the direct-S modes produced by horizontal-force sources, geothermal operators can acquire direct-S data across many more prospect areas than can be done with horizontal-force sources, which presently are limited to horizontal vibrators. We include some of our preliminary work in evaluating direct-S modes produced by vertical-force sources.

Hardage, Bob A; DeAngelo, Michael V; Ermolaeva, Elena; Hardage, Bob A; Remington, Randy; Sava, Diana; Wagner, Donald; Wei, Shuijion

2013-02-28T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Numerical simulations of the decay of primordial magnetic turbulence  

SciTech Connect

We perform direct numerical simulations of forced and freely decaying 3D magnetohydrodynamic turbulence in order to model magnetic field evolution during cosmological phase transitions in the early Universe. Our approach assumes the existence of a magnetic field generated either by a process during inflation or shortly thereafter, or by bubble collisions during a phase transition. We show that the final configuration of the magnetic field depends on the initial conditions, while the velocity field is nearly independent of initial conditions.

Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C (Canada); Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Brandenburg, Axel [Nordita, AlbaNova University Center, Roslagstullsbacken 23, 10691 Stockholm (Sweden); Department of Astronomy, Stockholm University, SE 10691 Stockholm (Sweden); Tevzadze, Alexander G. [Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Faculty of Exact and Natural Sciences, Tbilisi State University, 1 Chavchavadze Avenue Tbilisi, GE-0128 (Georgia); Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2010-06-15T23:59:59.000Z

362

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

363

Nonlocal Phenomenology for anisotropic MHD turbulence  

E-Print Network (OSTI)

A non-local cascade model for anisotropic MHD turbulence in the presence of a guiding magnetic field is proposed. The model takes into account that (a) energy cascades in an anisotropic manner and as a result a different estimate for the cascade rate in the direction parallel and perpendicular to the guiding field is made. (b) the interactions that result in the cascade are between different scales. Eddies with wave numbers $k_\\|$ and $k_\\perp$ interact with eddies with wave numbers $q_\\|,q_\\perp$ such that a resonance condition between the wave numbers $q_\\|,q_\\perp$ and $k_\\|,k_\\perp$ holds. As a consequence energy from the eddy with wave numbers $k_\\|$ and $k_\\perp$ cascades due to interactions with eddies located in the resonant manifold whose wavenumbers are determined by: $q_\\|\\simeq \\epsilon^{{1}/{3}}k_\\perp^{2/3}/B$, $q_\\perp=k_\\perp$ and energy will cascade along the lines $k_\\|\\sim C+k_\\perp^{2/3} \\epsilon^{1/3}/B_0$. For a uniform energy injection rate in the parallel direction the resulting energy...

Alexakis, Alexandros

2007-01-01T23:59:59.000Z

364

Field Verification of ADCP Surface Gravity Wave Elevation Spectra  

Science Conference Proceedings (OSTI)

Acoustic Doppler current profilers (ADCPs) can measure orbital velocities induced by surface gravity waves, yet the ADCP estimates of these velocities are subject to a relatively high noise level. The present paper introduces a linear filtration ...

A. J. F. Hoitink; H. C. Peters; M. Schroevers

2007-05-01T23:59:59.000Z

365

Energy Flux and Wavelet Diagnostics of Secondary Mountain Waves  

Science Conference Proceedings (OSTI)

In recent years, aircraft data from mountain waves have been primarily analyzed using velocity and temperature power spectrum and momentum flux estimation. Herein it is argued that energy flux wavelets (i.e., pressure–velocity wavelet cross-...

Bryan K. Woods; Ronald B. Smith

2010-11-01T23:59:59.000Z

366

Fast Turbulent Reconnection  

E-Print Network (OSTI)

Reconnection is the process by which magnetic fields in a conducting fluid change their topology. This process is essential for understanding a wide variety of astrophysical processes, including stellar and galactic dynamos and astrophysical turbulence. To account for solar flares, solar cycles and the structure of the galactic magnetic field reconnection must be fast, propagating with a speed close to the Alfven speed. We show that the presence of a random magnetic field component substantially enhances the reconnection rate and enables fast reconnection, i.e. reconnection that does not depend on fluid resistivity. The enhancement of the reconnection rate is achieved via a combination of two effects. First of all, only small segments of magnetic field lines are subject to direct Ohmic annihilation. Thus the fraction of magnetic energy that goes directly into fluid heating goes to zero as fluid resistivity vanishes. However, the most important enhancement comes from the fact that unlike the laminar fluid case where reconnection is constrained to proceed line by line, the presence of turbulence enables many magnetic field lines to enter the reconnection zone simultaneously. A significant fraction of magnetic energy goes into MHD turbulence and this enhances reconnection rates through an increase in the field stochasticity. In this way magnetic reconnection becomes fast when field stochasticity is accounted for. As a consequence solar and galactic dynamos are also fast, i.e. do not depend on fluid resistivity.

A. Lazarian; E. Vishniac

2000-02-03T23:59:59.000Z

367

Vertical Velocity Focus Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Velocity Focus Group Velocity Focus Group ARM 2008 Science Team Meeting Norfolk, VA March 10-14 Background Vertical velocity measurements have been at the top of the priority list of the cloud modeling community for some time. Doppler measurements from ARM profiling radars operating at 915-MHz, 35-GHz and 94-GHz have been largely unexploited. The purpose of this new focus group is to develop vertical velocity ARM products suitable for modelers. ARM response to their request has been slow. Most ARM instruments are suitable for cloud observations and have limited capabilities in precipitation Using ARM datasets for evaluating and improving cloud parameterization in global climate models (GCMs) is not straightforward, due to gigantic scale mismatches. Consider this... Looking only vertically drastically limits opportunities

368

ARM - Measurement - Vertical velocity  

NLE Websites -- All DOE Office Websites (Extended Search)

govMeasurementsVertical velocity govMeasurementsVertical velocity 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 : Vertical velocity The component of the velocity vector, along the local vertical. Categories Atmospheric State 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 KAZR : Ka ARM Zenith Radar MMCR : Millimeter Wavelength Cloud Radar SODAR : Mini Sound Detection and Ranging

369

Cirrus Crystal Terminal Velocities  

Science Conference Proceedings (OSTI)

Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth’s radiation balance through their effect on the rate of ...

Andrew J. Heymsfield; Jean Iaquinta

2000-04-01T23:59:59.000Z

370

SURFACE ALFVEN WAVES IN SOLAR FLUX TUBES  

SciTech Connect

Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. Alfven waves and magneto-sonic waves are particular classes of MHD waves. These wave modes are clearly different and have pure properties in uniform plasmas of infinite extent only. Due to plasma non-uniformity, MHD waves have mixed properties and cannot be classified as pure Alfven or magneto-sonic waves. However, vorticity is a quantity unequivocally related to Alfven waves as compression is for magneto-sonic waves. Here, we investigate MHD waves superimposed on a one-dimensional non-uniform straight cylinder with constant magnetic field. For a piecewise constant density profile, we find that the fundamental radial modes of the non-axisymmetric waves have the same properties as surface Alfven waves at a true discontinuity in density. Contrary to the classic Alfven waves in a uniform plasma of infinite extent, vorticity is zero everywhere except at the cylinder boundary. If the discontinuity in density is replaced with a continuous variation of density, vorticity is spread out over the whole interval with non-uniform density. The fundamental radial modes of the non-axisymmetric waves do not need compression to exist unlike the radial overtones. In thin magnetic cylinders, the fundamental radial modes of the non-axisymmetric waves with phase velocities between the internal and the external Alfven velocities can be considered as surface Alfven waves. On the contrary, the radial overtones can be related to fast-like magneto-sonic modes.

Goossens, M.; Andries, J.; Soler, R.; Van Doorsselaere, T. [Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Arregui, I.; Terradas, J., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

2012-07-10T23:59:59.000Z

371

Renormalized weak plasma turbulence theory  

SciTech Connect

A renormalized Vlasov turbulence theory, derived by neglecting a mode coupling term in the Direct Interaction Approximation, is discussed. The theory reduces correctly to weak turbulence theory; it predicts both diffusion and polarization effects of the turbulent medium on test particles, as well as the inverse effects of the test particles on the medium. A heuristic, physical algorithm is presented for constructing the equations. The theory of the renormalized dielectric function is reviewed.

Krommes, J.A.; Kleva, R.G.

1979-02-01T23:59:59.000Z

372

An Experimental Study of the Velocity-Forced Flame Response of Lean-Fremixed Multi-Nozzle Can Combustor for Gas Turbines.  

E-Print Network (OSTI)

??The velocity forced flame response of a multi-nozzle, lean-premixed, swirl-stabilized, turbulent combustor was investigated at atmospheric pressure. The purpose of this study was to analyze… (more)

Szedlmayer, Michael

2013-01-01T23:59:59.000Z

373

Filtering Turbulent Sparsely Observed Geophysical Flows  

Science Conference Proceedings (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

374

Measurements of Enhanced Turbulent Mixing near Highways  

Science Conference Proceedings (OSTI)

In August and September of 2010, measurements of turbulent fluxes and turbulent kinetic energy were made on highways in the Toronto area (Ontario, Canada). In situ turbulence measurements were made with a mobile laboratory while driving on the ...

Mark Gordon; Ralf M. Staebler; John Liggio; Paul Makar; Shao-Meng Li; Jeremy Wentzell; Gang Lu; Patrick Lee; Jeffrey R. Brook

2012-09-01T23:59:59.000Z

375

Simulation of turbulence in fireballs  

SciTech Connect

The ALE technique is applied to the calculation of a small yield, low altitude nuclear explosion. When artificial diffusion effects caused by numerical errors are minimized, the fireball rises too rapidly, reaching an altitude in excess of that which is observed. This suggests that turbulent diffusion and entrainmert may be important. Hence, a turbulence model has been added to later calculations of the fireball dynamics. Some of the more important features of the calculational technique and the turbulence model are discussed. Preliminary results for a set of turbulence parameters and a particular low altitude fireball are presented. (auth)

Ruppel, H.M.; Gentry, R.A.; Daly, B.J.

1973-11-01T23:59:59.000Z

376

Haynes Wave Basin | Open Energy Information  

Open Energy Info (EERE)

Wave Basin Wave Basin Jump to: navigation, search Basic Specifications Facility Name Haynes Wave Basin Overseeing Organization Texas A&M (Haynes) Hydrodynamic Testing Facility Type Wave Basin Length(m) 38.1 Beam(m) 22.9 Depth(m) 1.5 Water Type Freshwater Cost(per day) $150/hour (excluding labor) Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.6 Maximum Wave Height(m) at Wave Period(s) 3.3 Maximum Wave Length(m) 10.7 Wave Period Range(s) 3.3 Current Velocity Range(m/s) 0.2 Programmable Wavemaking Yes Wavemaking Description Directional, irregular, any spectrum, cnoidal or solitary wave Wave Direction Both Simulated Beach Yes Description of Beach Stone Channel/Tunnel/Flume Channel/Tunnel/Flume None

377

Hinsdale Wave Basin 2 | Open Energy Information  

Open Energy Info (EERE)

Wave Basin 2 Wave Basin 2 Jump to: navigation, search Basic Specifications Facility Name Hinsdale Wave Basin 2 Overseeing Organization Oregon State University Hydrodynamics Length(m) 48.8 Beam(m) 26.5 Depth(m) 2.1 Water Type Freshwater Cost(per day) $3500 Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.8 Maximum Wave Height(m) at Wave Period(s) 10.0 Wave Period Range(s) 10.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Monochromatic waves (cnoidal, Stokes, Airy), solitary waves, user-defined free surface timeseries or board displacement timeseries for random waves Wave Direction Both Simulated Beach Yes Description of Beach Built to client specifications, currently rigid concrete over gravel fill

378

Rossby Waves in Zonal Barotropic Flows with Pseudocritical Levels  

Science Conference Proceedings (OSTI)

A pseudocritical level is defined as a region where the wave phase speed c equals the zonal basic flow velocity U and, additionally, the background potential vorticity gradient vanishes. In this study Rossby wave propagation is investigated in ...

Uwe Harlander

2002-09-01T23:59:59.000Z

379

Numerical simulation of three-dimensional breaking waves on a gravel slope using a two-phase flow Navier-Stokes model  

Science Conference Proceedings (OSTI)

Wave breaking is mainly a three-dimensional flow problem characterized by wave energy dissipation due to turbulence. The understanding of the wave breaking mechanism on a beach is essential in studying coastal processes. The complexity of the wave-induced ... Keywords: CFD, Porous medium, Two phase, VOF, Wave breaking

P. Higuera; M. Del Jesus; J. L. Lara; I. J. Losada; Y. Guanche; G. Barajas

2013-07-01T23:59:59.000Z

380

Turbulent Combustion Properties of Premixed Syngases  

NLE Websites -- All DOE Office Websites (Extended Search)

Turbulent Combustion Properties of Premixed Syngases Title Turbulent Combustion Properties of Premixed Syngases Publication Type Journal Article Year of Publication 2009 Authors...

Note: This page contains sample records for the topic "turbulence velocity wave" 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

Simulation of lean premixed turbulent combustion  

E-Print Network (OSTI)

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

2008-01-01T23:59:59.000Z

382

Advanced Computational Methods for Turbulence and Combustion...  

NLE Websites -- All DOE Office Websites (Extended Search)

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

383

Supercomputers Capture Turbulence in the Solar Wind  

NLE Websites -- All DOE Office Websites (Extended Search)

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

384

Detectability of gravitational waves from phase transitions  

Science Conference Proceedings (OSTI)

Gravitational waves potentially represent our only direct probe of the universe when it was less than one second old. In particular, first-order phase transitions in the early universe can generate a stochastic background of gravitational waves which may be detectable today. We briefly summarize the physical sources of gravitational radiation from phase transitions and present semianalytic expressions for the resulting gravitational wave spectra from three distinct realistic sources: bubble collisions, turbulent plasma motions, and inverse-cascade helical magnetohydrodynamic turbulence. Using phenomenological parameters to describe phase transition properties, we determine the region of parameter space for which gravitational waves can be detected by the proposed Laser Interferometer Space Antenna. The electroweak phase transition is detectable for a wide range of parameters.

Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); CCPP, New York University, 4 Washington Plaza, New York, New York 10003 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Kosowsky, Arthur [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, Pennsylvania 15260 (United States); Gogoberidze, Grigol [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Centre for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Maravin, Yurii [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2008-08-15T23:59:59.000Z

385

Magnetohydrodynamic lattice Boltzmann simulations of turbulence and rectangular jet flow  

E-Print Network (OSTI)

Magnetohydrodynamic (MHD) investigations of decaying isotropic turbulence and rectangular jets (RJ) are carried out. A novel MHD lattice Boltzmann scheme that combines multiple relaxation time (MRT) parameters for the velocity field with a single 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-rate tensor are evaluated to assess the key physical MHD turbulence mechanisms. The magnetic and kinetic energies interact and exchange through the influence of the Lorentz force work. An initial random fluctuating magnetic field increases the vortex stretching and forward cascade mechanisms. A strong uniform mean magnetic field increases the anisotropy of the turbulent flow field and causes inverse cascading. In the RJ studies, an investigation into the MHD effects on velocity, instability, and the axis-switching phenomena is performed at various magnetic field strengths and Magnetic Reynolds Numbers. The magnetic field is found to decelerate the jet core, inhibit instability, and prevent axis-switching. The key physical mechanisms are: (i) the exchange of energy between kinetic and magnetic modes and (ii) the magnetic field effect on the vorticity evolution. From these studies, it is found that magnetic field influences momentum, vorticity, and energy evolution and the degree of modification depends on the field strength. This interaction changes vortex evolution, and alters turbulence processes and rectangular jet flow characteristics. Overall, this study provides more insight into the physics of MHD flows, which suggests possible applications of MHD Flow Control.

Riley, Benjamin Matthew

2007-05-01T23:59:59.000Z

386

Lewis number effects on turbulent premixed flame structure  

DOE Green Energy (OSTI)

The influence of the Lewis number on turbulent flame front geometry is investigated in a premixed turbulent stagnation point flame. A laser tomography technique is used to obtain the flame shape, a fractal analysis of the multiscale flame edges is performed and the distribution of local flame front curvature is determined. Lean H[sub 2]/Air and C[sub 3]H[sub 8]/Air mixtures with similar burning rates were investigated with Lewis numbers of 0.33 and 1.85 respectively. At the conditions studied the laminar H[sub 2]/Air mixture is unstable and a cellular structure is observed. Turbulence in the reactant is generated by a perforated plate and the turbulent length scale (3mm) and intensity (7%) at the nozzle exit are fixed. The equivalence ratio is set so that the burning velocity is the same for all the cases. Results show clearly that the turbulent flame surface area is dependent on the Lewis number. For a Lewis number less than unity surface area production is observed. The shape of the flame front curvature distribution is not found to be very sensitive to the Lewis number. For the H[sub 2]/Air mixture the distribution is skewed toward the positive values indicating the presence of cusps while for the C[sub 3]H[sub 8]/Air mixture the distribution is more symmetrical. In both cases the average curvature is found to be zero, and if the local burning speed varies linearly with curvature, the local positive and negative burning velocity variations due to curvature will balance.

Goix, P.J. (Centre National de la Recherche Scientifique (CNRS), 230 - Mont-Saint-Aignan (France). URA CORIA); Shepherd, I.G. (Lawrence Berkeley Lab., CA (United States))

1992-09-01T23:59:59.000Z

387

Lewis number effects on turbulent premixed flame structure  

DOE Green Energy (OSTI)

The influence of the Lewis number on turbulent flame front geometry is investigated in a premixed turbulent stagnation point flame. A laser tomography technique is used to obtain the flame shape, a fractal analysis of the multiscale flame edges is performed and the distribution of local flame front curvature is determined. Lean H{sub 2}/Air and C{sub 3}H{sub 8}/Air mixtures with similar burning rates were investigated with Lewis numbers of 0.33 and 1.85 respectively. At the conditions studied the laminar H{sub 2}/Air mixture is unstable and a cellular structure is observed. Turbulence in the reactant is generated by a perforated plate and the turbulent length scale (3mm) and intensity (7%) at the nozzle exit are fixed. The equivalence ratio is set so that the burning velocity is the same for all the cases. Results show clearly that the turbulent flame surface area is dependent on the Lewis number. For a Lewis number less than unity surface area production is observed. The shape of the flame front curvature distribution is not found to be very sensitive to the Lewis number. For the H{sub 2}/Air mixture the distribution is skewed toward the positive values indicating the presence of cusps while for the C{sub 3}H{sub 8}/Air mixture the distribution is more symmetrical. In both cases the average curvature is found to be zero, and if the local burning speed varies linearly with curvature, the local positive and negative burning velocity variations due to curvature will balance.

Goix, P.J. [Centre National de la Recherche Scientifique (CNRS), 230 - Mont-Saint-Aignan (France). URA CORIA; Shepherd, I.G. [Lawrence Berkeley Lab., CA (United States)

1992-09-01T23:59:59.000Z

388

Proton, Electron, and Ion Heating in the Fast Solar Wind from Nonlinear Coupling Between Alfvenic and Fast-Mode Turbulence  

E-Print Network (OSTI)

In the parts of the solar corona and solar wind that experience the fewest Coulomb collisions, the component proton, electron, and heavy ion populations are not in thermal equilibrium with one another. Observed differences in temperatures, outflow speeds, and velocity distribution anisotropies are useful constraints on proposed explanations for how the plasma is heated and accelerated. This paper presents new predictions of the rates of collisionless heating for each particle species, in which the energy input is assumed to come from magnetohydrodynamic (MHD) turbulence. We first created an empirical description of the radial evolution of Alfven, fast-mode, and slow-mode MHD waves. This model provides the total wave power in each mode as a function of distance along an expanding flux tube in the high-speed solar wind. Next we solved a set of cascade advection-diffusion equations that give the time-steady wavenumber spectra at each distance. An approximate term for nonlinear coupling between the Alfven and fas...

Cranmer, Steven R

2012-01-01T23:59:59.000Z

389

Magnetized Turbulent Dynamo in Protogalaxies  

Science Conference Proceedings (OSTI)

The prevailing theory for the origin of cosmic magnetic fields is that they have been amplified to their present values by the turbulent dynamo inductive action in the protogalactic and galactic medium. Up to now, in calculation of the turbulent dynamo, it has been customary to assume that there is no back reaction of the magnetic field on the turbulence, as long as the magnetic energy is less than the turbulent kinetic energy. This assumption leads to the kinematic dynamo theory. However, the applicability of this theory to protogalaxies is rather limited. The reason is that in protogalaxies the temperature is very high, and the viscosity is dominated by magnetized ions. As the magnetic field strength grows in time, the ion cyclotron time becomes shorter than the ion collision time, and the plasma becomes strongly magnetized. As a result, the ion viscosity becomes the Braginskii viscosity. Thus, in protogalaxies the back reaction sets in much earlier, at field strengths much lower than those which correspond to field-turbulence energy equipartition, and the turbulent dynamo becomes what we call the magnetized turbulent dynamo. In this paper we lay the theoretical groundwork for the magnetized turbulent dynamo. In particular, we predict that the magnetic energy growth rate in the magnetized dynamo theory is up to ten times larger than that in the kinematic dynamo theory. We also briefly discuss how the Braginskii viscosity can aid the development of the inverse cascade of magnetic energy after the energy equipartition is reached.

Leonid Malyshkin; Russell M. Kulsrud

2002-01-28T23:59:59.000Z

390

Scrape-off layer tokamak plasma turbulence  

Science Conference Proceedings (OSTI)

Two-dimensional (2D) interchange turbulence in the scrape-off layer of tokamak plasmas and their subsequent contribution to anomalous plasma transport has been studied in recent years using electron continuity, current balance, and electron energy equations. In this paper, numerically it is demonstrated that the inclusion of ion energy equation in the simulation changes the nature of plasma turbulence. Finite ion temperature reduces floating potential by about 15% compared with the cold ion temperature approximation and also reduces the radial electric field. Rotation of plasma blobs at an angular velocity about 1.5 Multiplication-Sign 10{sup 5} rad/s has been observed. It is found that blob rotation keeps plasma blob charge separation at an angular position with respect to the vertical direction that gives a generation of radial electric field. Plasma blobs with high electron temperature gradients can align the charge separation almost in the radial direction. Influence of high ion temperature and its gradient has been presented.

Bisai, N.; Singh, R.; Kaw, P. K. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

2012-05-15T23:59:59.000Z

391

Dissipation of Nonlinear Alfven Waves with Current Sheets in Relativistic Plasmas  

E-Print Network (OSTI)

We present results from 2.5-dimensional Particle-in-Cell simulations of the interaction of nonlinear Alfven waves with thin current sheets in relativistic plasmas. We find that the Alfven waves cause the current sheet to bend and kink and increase its dissipation. The electrons are eventually heated to form a double Maxwellian, with the hotter Maxwellian caused by the current sheet dissipation and cooler Maxwellian caused by the Alfven turbulence cascade. These results may have important implications for the kinetic dissipation of MHD turbulence in which both nonlinear Alfven waves and current sheets are present, such as turbulence in accretion flows driven by the saturated magnetorotational instability (MRI).

Liang, Edison

2009-01-01T23:59:59.000Z

392

Perspectives on Deposition Velocity  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Deposition Deposition Velocity ... Going down the rabbit hole to explain that sinking feeling Brian DiNunno, Ph.D. Project Enhancement Corporation June 6 th , 2012 Discussion Framework ď‚— Development of the HSS Deposition Velocity Safety Bulletin ď‚— Broader discussion of appropriate conservatism within dispersion modeling and DOE-STD-3009 DOE-STD-3009 Dose Comparison "General discussion is provided for source term calculation and dose estimation, as well as prescriptive guidance for the latter. The intent is that calculations be based on reasonably conservative estimates of the various input parameters." - DOE-STD-3009, Appendix A.3 DOE-STD-3009 Dispersion

393

Velocity pump reaction turbine  

DOE Patents (OSTI)

An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

House, Palmer A. (Walnut Creek, CA)

1982-01-01T23:59:59.000Z

394

Velocity pump reaction turbine  

DOE Patents (OSTI)

An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

House, Palmer A. (Walnut Creek, CA)

1984-01-01T23:59:59.000Z

395

Measurements in film cooling flows: Hole L/D and turbulence intensity effects  

DOE Green Energy (OSTI)

Hot-wire anemometry of simulated film cooling was used to study the influence of freestream turbulence intensity and film cooling hole length-to-diameter ratio on mean velocity and turbulence intensity. Measurements were made in the zone where the coolant and freestream flows mix. Flow from one row of film cooling holes with a streamwise injection of 35{degree} and no lateral injection and with a coolant- to-freestream flow velocity ratio of 1.0 was investigated under freestream turbulence levels of 0.5 and 12%. Coolant-to-freestream density ratio was unity. Two length-to-diameter ratios for the film cooling holes, 2.3 and 7.0, are tested. Results show that under low freestream turbulence conditions, pronounced differences exist in the flowfield between L/D=7.0 and 2.3; the differences are less prominent at high freestream turbulence intensities. Generally, short-L/D injection results in ``jetting`` of the coolant further into the freestream flow and enhanced mixing. Other changes in the flowfield attributable to a rise in freestream turbulence intensity to engine- representative conditions are documented. 15 figs, 2 tabs, refs.

Burd, S.W.; Kaszeta, R.W.; Simon, T.W.

1996-12-31T23:59:59.000Z

396

A Model of Strongly Forced Wind Waves  

Science Conference Proceedings (OSTI)

A model of surface waves generated on deep water by strong winds is proposed. A two-layer approximation is adopted, in which a shallow turbulent layer overlies the lower, infinitely deep layer. The dynamics of the upper layer, which is directly ...

Alexey V. Fedorov; W. Kendall Melville

2009-10-01T23:59:59.000Z

397

Alden Wave Basin | Open Energy Information  

Open Energy Info (EERE)

Wave Basin Wave Basin Jump to: navigation, search Basic Specifications Facility Name Alden Wave Basin Overseeing Organization Alden Research Laboratory, Inc Hydrodynamic Testing Facility Type Wave Basin Length(m) 33.5 Beam(m) 21.3 Depth(m) 1.2 Water Type Freshwater Cost(per day) Depends on study Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.3 Maximum Wave Height(m) at Wave Period(s) 1.0 Maximum Wave Length(m) 1.8 Wave Period Range(s) 1.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Period adjustable electronically, height adjustable mechanically Wave Direction Both Simulated Beach Yes Description of Beach Designed as needed using commercially available sand/sediment

398

Uncertainty in a Path-averaged Measurement of the Friction Velocity u*  

Science Conference Proceedings (OSTI)

Several electro-optical methods exist for measuring a path-averaged value of the inner scale of turbulence l0. By virtue of Monin–Obukhov similarity, in the atmospheric surface layer such l0 measurements are related to the friction velocity u* or ...

Edgar L. Andreas

1992-11-01T23:59:59.000Z

399

On Collective Properties of Turbulent QED Plasma  

E-Print Network (OSTI)

Polarization properties of turbulent stochastically inhomogeneous ultrarelativistic QED plasma are studied. It is shown that the sign of nonlinear turbulent Landau damping corresponds to an instability of the spacelike modes and, for sufficiently large turbulent fields, to an actual instability of a system. Modification of plasmon dispersion relations due to turbulent effects are studied.

Martin Kirakosyan; Andrei Leonidov; Berndt Muller

2013-05-19T23:59:59.000Z

400

Star formation in molecular cores III. The effect of the turbulent power spectrum  

E-Print Network (OSTI)

We investigate the effect of the turbulent power spectrum (P(k) \\propto k^{-n}, with n=3, 4 or 5) on the fragmentation of low-mass cores, by means of SPH simulations. We adopt initial density profiles and low levels of turbulence based on observation, and for each n-value we conduct an ensemble of simulations with different initial seeds for the turbulent velocity field, so as to obtain reasonable statistics. We find that when power is concentrated at larger scales (i.e. for larger n), more protostellar objects form and there is a higher proportion of low-mass stars and brown dwarfs. This is in direct contrast with the recent results of Delgado Donate et al., presumably because they adopted much higher levels of turbulence.

S. P. Goodwin; A. P. Whitworth; D. Ward-Thompson

2006-02-28T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

The Stellar IMF as a Property of Turbulence  

E-Print Network (OSTI)

We propose to interpret the stellar IMF as a property of the turbulence in the star--forming gas. Gravitationally unstable density enhancements in the turbulent flow collapse and form stars. Their mass distribution can be derived analytically from the power spectrum of the turbulent flow and the isothermal shock jump conditions in the magnetized gas. For a power spectrum index \\beta=1.74, consistent with Larson's velocity dispersion--size relation as well as with new numerical and analytic results on supersonic turbulence, we obtain a power law mass distribution of dense cores with a slope equal to 3/(4-\\beta)=1.33, consistent with the slope of Salpeter's stellar IMF. Below one solar mass, the mass distribution flattens and turns around at a fraction of a solar mass, as observed for the stellar IMF in a number of stellar clusters, because only the densest cores are gravitationally unstable. The mass distribution at low masses is determined by the Log--Normal distribution of the gas density. The intermittent nature of this distribution is responsible for the generation of a significant number of collapsing cores of brown dwarf mass.

Paolo Padoan; Ake Nordlund

2004-11-16T23:59:59.000Z

402

Freely propagating open premixed turbulent flames stabilized by swirl  

DOE Green Energy (OSTI)

A novel means has been developed for using weak swirl to stabilize freely propagating open premixed turbulent flames (swirl numbers between 0.05 to 0.3). By injecting a small amount of air tangentially into the co-flow of a concentric burner, stationary flames can be maintained above the burner exit for a large range of mixture, turbulence and flow conditions. The absence of physical surfaces in the vicinity of the flame provides free access to laser diagnostics. Laser Doppler anemometry and laser Mie scattering measurements of four flames with and without incident turbulence show that their features are typical of wrinkled laminar flames. The most distinct characteristics is that flame stabilization does not rely on flow recirculation. Centrifugal force induced by swirl causes flow divergence, and the flame is maintained at where the local mass flux balances the burning rate. The flame speeds can be estimated based on the centerline velocity vector, which is locally normal to the flame brush. This flame geometry is the closest approximation to the 1-D planar flame for determining fundamental properties to advance turbulent combustion theories. 18 refs.

Chan, C.K.; Lau, K.S.; Chin, W.K. (Hong Kong Polytechnic, Kowloon (Hong Kong)); Cheng, R.K. (Lawrence Berkeley Lab., CA (United States))

1991-12-01T23:59:59.000Z

403

Internal Waves in Monterey Submarine Canyon  

Science Conference Proceedings (OSTI)

Velocity, temperature, and salinity profile surveying in Monterey Submarine Canyon during spring tide reveals an internal wave field almost an order of magnitude more energetic than that in the open ocean. Semidiurnal fluctuations and their ...

Eric Kunze; Leslie K. Rosenfeld; Glenn S. Carter; Michael C. Gregg

2002-06-01T23:59:59.000Z

404

Shear Excitation of Atmospheric Gravity Waves  

Science Conference Proceedings (OSTI)

Unstable Velocity shears are a Common source of vertically propagating gravity waves in the atmosphere. However, the growth rates of unstable modes predicted by linear theory cannot always amount for their observed importance.

David C. Fritts

1982-09-01T23:59:59.000Z

405

Internal Gravity Wave Generation and Hydrodynamic Instability  

Science Conference Proceedings (OSTI)

Two mechanisms are proposed whereby internal gravity waves (IGW) may radiate from a linearly unstable region of Boussinesq parallel flow that is characterized in the far field by constant horizontal velocity and Brunt-Väisälä frequency. Through ...

B. R. Sutherland; C. P. Caulfield; W. R. Peltier

1994-11-01T23:59:59.000Z

406

Energy Dispersion in African Easterly Waves  

Science Conference Proceedings (OSTI)

The existence of an upstream (eastward) group velocity for African easterly waves (AEWs) is shown based on single-point lag regressions using gridded reanalysis data from 1990 to 2010. The eastward energy dispersion is consistent with the ...

Michael Diaz; Anantha Aiyyer

2013-01-01T23:59:59.000Z

407

On the Nature of Turbulence in a Stratified Fluid. Part II: Application to Lakes  

Science Conference Proceedings (OSTI)

A strong debate has continued for a number of years over the magnitude of the ratio of the buoyancy flux b to the rate of production of turbulent kinetic energy from the mean velocity sheer. This ratio has traditionally been called the flux ...

J. Imberger; G. N. Ivey

1991-05-01T23:59:59.000Z

408

SPH Simulation of transition to turbulence for planar shear flow subjected to a streamwise magnetic field  

Science Conference Proceedings (OSTI)

Active flow control of electrically conducting fluids finds growing importance in the metallurgical industry. A magnetic field applied in the streamwise direction of electrically conducting fluid flow restrains the velocity fluctuations in the transverse ... Keywords: CFD, magnetohydrodynamics, simulation, smoothed particle hydrodynamics, turbulence control

Fangming Jiang; Mónica S. A. Oliveira; Antonio C. M. Sousa

2006-09-01T23:59:59.000Z

409

Internal Tides and Turbulence along the 3000-m Isobath of the Hawaiian Ridge  

Science Conference Proceedings (OSTI)

Full-depth velocity and density profiles taken along the 3000-m isobath characterize the semidiurnal internal tide and bottom-intensified turbulence along the Hawaiian Ridge. Observations reveal baroclinic energy fluxes of 21 ± 5 kW m?1 radiating ...

Craig M. Lee; Thomas B. Sanford; Eric Kunze; Jonathan D. Nash; Mark A. Merrifield; Peter E. Holloway

2006-06-01T23:59:59.000Z

410

Active Turbulence and Scalar Transport near the Forest–Atmosphere Interface  

Science Conference Proceedings (OSTI)

Turbulent velocity, temperature, water vapor concentration, and other scalars were measured at the canopy–atmosphere interface of a 13–14-m-tall uniform pine forest and a 33-m-tall nonuniform hardwood forest. These measurements were used to ...

Gabriel G. Katul; Chris D. Geron; Cheng-I. Hsieh; Brani Vidakovic; Alex B. Guenther

1998-12-01T23:59:59.000Z

411

Measurement of Turbulence in the Oceanic Bottom Boundary layer with an Acoustic Current Meter Array  

Science Conference Proceedings (OSTI)

A vertical array of acoustic current meters measures the vector flow field in the lowest 5 m of the oceanic boundary layer. By resolving the velocity to 0.03 cm s?1 over 15 cm paths, it samples the dominant turbulent eddies responsible for ...

Albert J. Williams 3rd; John S. Tochko; Richard L. Koehler; William D. Grant; Thomas F. Gross; Christopher V. R. Dunn

1987-06-01T23:59:59.000Z

412

On the Use of Hot-Wire Anemometers for Turbulence Measurements in Clouds  

Science Conference Proceedings (OSTI)

The use of a hot-wire anemometer for high-resolution turbulence measurements in a two-phase flow (e.g., atmospheric clouds) is discussed. Experiments in a small wind tunnel (diameter of 0.2 and 2 m in length) with a mean flow velocity in the ...

Holger Siebert; Katrin Lehmann; Raymond A. Shaw

2007-06-01T23:59:59.000Z

413

Plasma beat-wave accelerator  

Science Conference Proceedings (OSTI)

We perform an analytic study of some quantities relevant to the plasma beat-wave accelerator (PBWA) concept. We obtain analytic expressions for the plasma frequency, longitudinal electron velocity, plasma density and longitudinal plasma electric field of a nonlinear longitudinal electron plasma oscillation with amplitude less than the wave-breaking limit and phase velocity approaching the speed of light. We also estimate the luminosity of a single-pass e/sup +/e/sup -/ linear PBWA collider assuming the energy and collision beamstrahlung are fixed parameters.

Noble, R.J.

1983-06-01T23:59:59.000Z

414

Thermal Instability and Magnetic Pressure in the Turbulent Interstellar Medium  

E-Print Network (OSTI)

We review recent results on the nonlinear development of thermal instability (TI) in the context of the turbulent atomic interstellar medium (ISM). First, we discuss the growth of entropy perturbations in isolation, as a function of the ratio \\eta of the cooling time to the dynamical crossing time. For \\eta~ 0.3) and occurs at scales with \\eta>1. We then consider the behavior of magnetic pressure in turbulent regimes. We propose that the reported lack of correlation between the magnetic pressure and the density is a consequence of the different scaling of the magnetic pressure with density for the slow and fast modes of nonlinear MHD waves. This implies that magnetic ``pressure'' is not a suitable candidate for supplementing thermal pressure in the presence of TI, and that polytropic descriptions of it are probably not adequate in the fully turbulent regime. Finally, we consider TI in a turbulent ISM-like medium. We find that the flow does not exhibit sharp phase transitions, as would be expected in classical...

Vázquez-Semadeni, E; Passot, T; Sánchez-Salcedo, F J; Vazquez-Semadeni, Enrique; Gazol, Adriana; Passot, Thierry; Sanchez-Salcedo, Javier

2003-01-01T23:59:59.000Z

415

Turbulence Regimes and Turbulence Intermittency in the Stable Boundary Layer during CASES-99  

Science Conference Proceedings (OSTI)

An investigation of nocturnal intermittent turbulence during the Cooperative Atmosphere–Surface Exchange Study in 1999 (CASES-99) revealed three turbulence regimes at each observation height: 1) regime 1, a weak turbulence regime when the wind ...

Jielun Sun; Larry Mahrt; Robert M. Banta; Yelena L. Pichugina

2012-01-01T23:59:59.000Z

416

Analysis of the influence of external biasing on Texas Helimak turbulence  

Science Conference Proceedings (OSTI)

We analyze alterations on the electrostatic turbulence in experiments with imposed bias to control the plasma radial electric field in Texas Helimak (K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)), a toroidal plasma device with a one-dimensional equilibrium, magnetic curvature, and shear. Comparing discharges from different biased potentials, we identify, in a roughly uniform gradient region, a continuous variation from low turbulence level and narrower frequency spectra, for negative bias, to high turbulence level and broadband spectra for positive bias. Overall, we distinguish two kinds of perturbed turbulence, classified according to their intensity, spectral, statistical, and recurrence properties. When the bias is positive, the turbulence shows enhanced and broadband spectra with non Gaussian probability distribution functions having noticeable long tails (extreme events) similar to the turbulence in tokamak scrape-off layer. On the other hand, negative bias reduces the turbulence level and decreases the spectrum widths. Also for negative bias, we found large frequency widths whenever the coupling between drift waves and the sheared plasma flow is fast enough to allow the enhancement of sidebands modes.

Toufen, D. L. [Institute of Physics, University of Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, Sao Paulo (Brazil); Federal Institute of Education, Science and Technology of Sao Paulo-IFSP, 07115-000 Guarulhos, Sao Paulo (Brazil); Guimaraes-Filho, Z. O.; Caldas, I. L. [Institute of Physics, University of Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, Sao Paulo (Brazil); Szezech, J. D. [Department of Physics, State University of Ponta Grossa, 84030-900 Parana (Brazil); Lopes, S.; Viana, R. L. [Department of Physics, Federal University of Parana, 81531-990 Curitiba, Parana (Brazil); Gentle, K. W. [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States)

2013-02-15T23:59:59.000Z

417

Predictability of Rotating Stratified Turbulence  

Science Conference Proceedings (OSTI)

Although predictability represents one of the fundamental problems in atmospheric science, gaps in our knowledge remain. Theoretical understanding of the inverse error cascade is limited mostly to homogeneous, isotropic turbulence, whereas ...

K. Ngan; P. Bartello; D. N. Straub

2009-05-01T23:59:59.000Z

418

An Intercomparison of Model-Predicted Wave Breaking for the 11 January 1972 Boulder Windstorm  

Science Conference Proceedings (OSTI)

Two-dimensional simulations of the 11 January 1972 Boulder, Colorado, windstorm, obtained from 11 diverse nonhydrostatic models, are intercompared with special emphasis on the turbulent breakdown of topographically forced gravity waves, as part ...

J. D. Doyle; D. R. Durran; C. Chen; B. A. Colle; M. Georgelin; V. Grubisic; W. R. Hsu; C. Y. Huang; D. Landau; Y. L. Lin; G. S. Poulos; W. Y. Sun; D. B. Weber; M. G. Wurtele; M. Xue

2000-03-01T23:59:59.000Z

419

DeFrees Large Wave Basin | Open Energy Information  

Open Energy Info (EERE)

Large Wave Basin Large Wave Basin Jump to: navigation, search Basic Specifications Facility Name DeFrees Large Wave Basin Overseeing Organization Cornell University Hydrodynamics Hydrodynamic Testing Facility Type Wave Basin Length(m) 32.0 Beam(m) 0.6 Depth(m) 0.9 Water Type Freshwater Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.5 Maximum Wave Height(m) at Wave Period(s) 3.0 Maximum Wave Length(m) 64 Wave Period Range(s) 3.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Computer controlled 4m hydraulic wave paddle stroke allows a series of solitary waves to be generated; arbitrary wave shape possible Wave Direction Uni-Directional Simulated Beach Yes

420

Intermittency in Turbulence  

E-Print Network (OSTI)

We derive from the Navier-Stokes equation an exact equation satisfied by the dissipation rate correlation function. We exploit its mathematical similarity to the corresponding equation derived from the 1-dimensional stochastic Burgers equation to determine the intermittency exponents in terms of the exponents characterizing the behavior of the dynamical velocity structure functions. We discuss the role of sweeping and Galilean invariance in determining the intermittency exponents

F. Hayot; C. Jayaprakash

1999-01-22T23:59:59.000Z

Note: This page contains sample records for the topic "turbulence velocity wave" 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

PROTON, ELECTRON, AND ION HEATING IN THE FAST SOLAR WIND FROM NONLINEAR COUPLING BETWEEN ALFVENIC AND FAST-MODE TURBULENCE  

Science Conference Proceedings (OSTI)

In the parts of the solar corona and solar wind that experience the fewest Coulomb collisions, the component proton, electron, and heavy ion populations are not in thermal equilibrium with one another. Observed differences in temperatures, outflow speeds, and velocity distribution anisotropies are useful constraints on proposed explanations for how the plasma is heated and accelerated. This paper presents new predictions of the rates of collisionless heating for each particle species, in which the energy input is assumed to come from magnetohydrodynamic (MHD) turbulence. We first created an empirical description of the radial evolution of Alfven, fast-mode, and slow-mode MHD waves. This model provides the total wave power in each mode as a function of distance along an expanding flux tube in the high-speed solar wind. Next, we solved a set of cascade advection-diffusion equations that give the time-steady wavenumber spectra at each distance. An approximate term for nonlinear coupling between the Alfven and fast-mode fluctuations is included. For reasonable choices of the parameters, our model contains enough energy transfer from the fast mode to the Alfven mode to excite the high-frequency ion cyclotron resonance. This resonance is efficient at heating protons and other ions in the direction perpendicular to the background magnetic field, and our model predicts heating rates for these species that agree well with both spectroscopic and in situ measurements. Nonetheless, the high-frequency waves comprise only a small part of the total Alfvenic fluctuation spectrum, which remains highly two dimensional as is observed in interplanetary space.

Cranmer, Steven R.; Van Ballegooijen, Adriaan A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-08-01T23:59:59.000Z

422

Application of the Lighthill–Ford Theory of Spontaneous Imbalance to Clear-Air Turbulence Forecasting  

Science Conference Proceedings (OSTI)

A new method of clear-air turbulence (CAT) forecasting based on the Lighthill–Ford theory of spontaneous imbalance and emission of inertia–gravity waves has been derived and applied on episodic and seasonal time scales. A scale analysis of this ...

John A. Knox; Donald W. McCann; Paul D. Williams

2008-10-01T23:59:59.000Z

423

Experimental Study on Kinematics and Dynamics of Breaking Waves in Deep Water  

E-Print Network (OSTI)

A new measurement technique called fiber optic reflectometer (FOR) was developed to investigate multiphase flows. The principle and setup of the FOR technique were introduced and applied to various experiments. Based on the coherently mixed signal between the Fresnel reflection off the fiber-liquid interface and the scattered signal off the object, such as a gas bubble, and a solid particle, this single probe technique is capable of simultaneously measuring the velocity of the object with a high accuracy and the phase of the fluid. In addition, bubble diameter, velocity, and void fraction were measured directly. By means of a simple modification of the FOR technique, solute concentration and refractive index change were measured with a greatly improved accuracy. This modified technique was used for measuring of a NaCl concentration in deionized water to validate a new normalization technique. In the second part of this thesis, a plunging breaking wave in deep water has been studied. Using the wave focusing method, a strong plunging breaker was generated with accuracy in the deep water condition in a two-dimensional wave tank. It was possible to describe the breaking process in detail using a high speed camera with a frame rate of 500 or 1000 fps. Four kinds of experimental techniques were employed or developed to investigate the plunging breaker. Bubble image velocimetry (BIV) and particle image velocimetry (PIV) were used to measure the velocity fields. The velocity fields of the highly aerated region were obtained from the BIV measurements. In addition, the modified PIV technique is capable of measuring the velocities in the entire flow field including the aerated region. Mean and turbulent properties were obtained by the ensemble average. The mean velocity, mean vorticity, and mean kinetic energy were examined over the entire flow field. In addition, the Reynolds stresses and turbulent kinetic energy were calculated with high temporal and spatial resolutions. Free surface elevation was obtained from wave gauge measurements. BIV and PIV images were also used to obtain the free surface elevation and the boundary of the aerated region for more accurate results. The FOR technique was used to obtain the void ratio at each splash-up region. Compressibility of the plunging breaker was considered. Mass flux, momentum flux, kinetic energy, and Reynolds stresses at each FOR station were recalculated using the void ratio obtained from the FOR measurements. All terms at the first splash-up region were highly overestimated more than 100 percent unless the void ratio was applied to the calculation of fluxes and energies. Compared with the fully developed first splash-up region, the overestimation at the second and third splash-up was less significant. However, most terms were overestimated by 20~30 percent when the void ratio was not considered.

Lim, Ho Joon

2010-08-01T23:59:59.000Z

424

Temporal Velocity Variations beneath the Coso Geothermal Field Observed  

Open Energy Info (EERE)

Velocity Variations beneath the Coso Geothermal Field Observed Velocity Variations beneath the Coso Geothermal Field Observed using Seismic Double Difference Tomography of Compressional and Shear Wave Arrival Times Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Temporal Velocity Variations beneath the Coso Geothermal Field Observed using Seismic Double Difference Tomography of Compressional and Shear Wave Arrival Times Details Activities (1) Areas (1) Regions (0) Abstract: Microseismic imaging can be an important tool for characterizing geothermal reservoirs. Since microseismic sources occur more or less continuously both due to the operations of a geothermal field and the naturally occurring background seismicity, passive seismic monitoring is well suited to quantify the temporal variations in the vicinity of a

425

The quenching of star formation in accretion-driven clumpy turbulent tori of active galactic nuclei  

E-Print Network (OSTI)

Galactic gas-gas collisions involving a turbulent multiphase ISM share common ISM properties: dense extraplanar gas visible in CO, large linewidths (>= 50 km/s), strong mid-infrared H_2 line emission, low star formation activity, and strong radio continuum emission. Gas-gas collisions can occur in the form of ICM ram pressure stripping, galaxy head-on collisions, compression of the intragroup gas and/or galaxy ISM by an intruder galaxy which flies through the galaxy group at a high velocity, or external gas accretion on an existing gas torus in a galactic center. We suggest that the common theme of all these gas-gas interactions is adiabatic compression of the ISM leading to an increase of the turbulent velocity dispersion of the gas. The turbulent gas clouds are then overpressured and star formation is quenched. Within this scenario we developed a model for turbulent clumpy gas disks where the energy to drive turbulence is supplied by external infall or the gain of potential energy by radial gas accretion wi...

Vollmer, B

2013-01-01T23:59:59.000Z

426

White light velocity interferometer  

DOE Patents (OSTI)

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

Erskine, D.J.

1997-06-24T23:59:59.000Z

427

White light velocity interferometer  

DOE Patents (OSTI)

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

Erskine, David J. (Oakland, CA)

1997-01-01T23:59:59.000Z

428

White light velocity interferometer  

DOE Patents (OSTI)

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

Erskine, David J. (Oakland, CA)

1999-01-01T23:59:59.000Z

429

White light velocity interferometer  

DOE Patents (OSTI)

The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

Erskine, D.J.

1999-06-08T23:59:59.000Z

430

Loop Equation in Turbulence  

E-Print Network (OSTI)

The incompressible fluid dynamics is reformulated as dynamics of closed loops $C$ in coordinate space. This formulation allows to derive explicit functional equation for the generating functional $\\Psi[C]$ in inertial range of spatial scales, which allows the scaling solutions. The requirement of finite energy dissipation rate leads then to the Kolmogorov index. We find an exact steady solution of the loop equation in inertial range of the loop sizes. The generating functional decreases as $\\EXP{-A^{\\tt}}$ where $A=\\oint_C r \\wedge dr$ is the area inside the loop. The pdf for the velocity circulation $\\Gamma$ is Lorentzian, with the width $\\bar{\\Gamma} \\propto A^{\\tt} $.

Alexander A. Migdal

1993-03-23T23:59:59.000Z

431

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

Science Conference Proceedings (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

432

Dynamic Multiscale Averaging (DMA) of Turbulent Flow  

SciTech Connect

A new approach called dynamic multiscale averaging (DMA) for computing the effects of turbulent flow is described. The new method encompasses multiple applications of temporal and spatial averaging, that is, multiscale operations. Initially, a direct numerical simulation (DNS) is performed for a relatively short time; it is envisioned that this short time should be long enough to capture several fluctuating time periods of the smallest scales. The flow field variables are subject to running time averaging during the DNS. After the relatively short time, the time-averaged variables are volume averaged onto a coarser grid. Both time and volume averaging of the describing equations generate correlations in the averaged equations. These correlations are computed from the flow field and added as source terms to the computation on the next coarser mesh. They represent coupling between the two adjacent scales. Since they are computed directly from first principles, there is no modeling involved. However, there is approximation involved in the coupling correlations as the flow field has been computed for only a relatively short time. After the time and spatial averaging operations are applied at a given stage, new computations are performed on the next coarser mesh using a larger time step. The process continues until the coarsest scale needed is reached. New correlations are created for each averaging procedure. The number of averaging operations needed is expected to be problem dependent. The new DMA approach is applied to a relatively low Reynolds number flow in a square duct segment. Time-averaged stream-wise velocity and vorticity contours from the DMA approach appear to be very similar to a full DNS for a similar flow reported in the literature. Expected symmetry for the final results is produced for the DMA method. The results obtained indicate that DMA holds significant potential in being able to accurately compute turbulent flow without modeling for practical engineering applications.

Richard W. Johnson

2012-09-01T23:59:59.000Z

433

Rapidly Sheared Compressible Turbulence: Characterization of Different Pressure Regimes and Effect of Thermodynamic Fluctuations  

E-Print Network (OSTI)

Rapid distortion theory (RDT) is applied to compressible ideal-gas turbulence subjected to homogeneous shear flow. The study examines the linear or rapid processes present in turbulence evolution. Specific areas of investigation include:(i) characterization of the multi-stage flow behavior,(ii) changing role of pressure in the three-regime evolution and (iii) influence of thermodynamic fluctuations on the different regimes. Preliminary investigations utilizing the more accurate Favre-averaged RDT approach show promise however, this approach requires careful validation and testing. In this study the Favre-averaged RDT approach is validated against Direct Numerical Simulation (DNS) and Reynolds-averaged RDT results. The three-stage growth of the flow field statistics is first confirmed. The three regime evolution of turbulence is then examined in three different timescales and the physics associated with each regime is discussed in depth. The changing role of pressure in compressible turbulence evolution shows three distinct stages. The physics of each stage is clearly explained. Next, the influence of initial velocity and thermodynamic fluctuations on the flow field are investigated. The evolution of turbulence is shown to be strongly dependent on the initial gradient Mach number and initial temperature fluctuations which tend to delay the onset of the second regime of evolution. The initial turbulent Mach number, which quantifies velocity fluctuations in the flow, influences turbulence evolution only weakly. Comparison of Reynolds-averaged RDT against Favre-averaged RDT for simulations of nonzero initial flow field fluctuations shows the higher fidelity of the latter approach.

Bertsch, Rebecca Lynne

2010-08-01T23:59:59.000Z

434

Fundamental Statistical Descriptions of Plasma Turbulence in Magnetic Fields  

SciTech Connect

A pedagogical review of the historical development and current status (as of early 2000) of systematic statistical theories of plasma turbulence is undertaken. Emphasis is on conceptual foundations and methodology, not practical applications. Particular attention is paid to equations and formalism appropriate to strongly magnetized, fully ionized plasmas. Extensive reference to the literature on neutral-fluid turbulence is made, but the unique properties and problems of plasmas are emphasized throughout. Discussions are given of quasilinear theory, weak-turbulence theory, resonance-broadening theory, and the clump algorithm. Those are developed independently, then shown to be special cases of the direct-interaction approximation (DIA), which provides a central focus for the article. Various methods of renormalized perturbation theory are described, then unified with the aid of the generating-functional formalism of Martin, Siggia, and Rose. A general expression for the renormalized dielectric function is deduced and discussed in detail. Modern approaches such as decimation and PDF methods are described. Derivations of DIA-based Markovian closures are discussed. The eddy-damped quasinormal Markovian closure is shown to be nonrealizable in the presence of waves, and a new realizable Markovian closure is presented. The test-field model and a realizable modification thereof are also summarized. Numerical solutions of various closures for some plasma-physics paradigms are reviewed. The variational approach to bounds on transport is developed. Miscellaneous topics include Onsager symmetries for turbulence, the interpretation of entropy balances for both kinetic and fluid descriptions, self-organized criticality, statistical interactions between disparate scales, and the roles of both mean and random shear. Appendices are provided on Fourier transform conventions, dimensional and scaling analysis, the derivations of nonlinear gyrokinetic and gyrofluid equations, stochasticity criteria for quasilinear theory, formal aspects of resonance-broadening theory, Novikov's theorem, the treatment of weak inhomogeneity, the derivation of the Vlasov weak-turbulence wave kinetic equation from a fully renormalized description, some features of a code for solving the direct-interaction approximation and related Markovian closures, the details of the solution of the EDQNM closure for a solvable three-wave model, and the notation used in the article.

John A. Krommes

2001-02-16T23:59:59.000Z

435

Tracking the dynamics of translation and absolute orientation of a sphere in a turbulent flow  

E-Print Network (OSTI)

We study the 6-dimensional dynamics -- position and orientation -- of a large sphere advected by a turbulent flow. The movement of the sphere is recorded with 2 high-speed cameras. Its orientation is tracked using a novel, efficient algorithm; it is based on the identification of possible orientation `candidates' at each time step, with the dynamics later obtained from maximization of a likelihood function. Analysis of the resulting linear and angular velocities and accelerations reveal a surprising intermittency for an object whose size lies in the integral range, close to the integral scale of the underlying turbulent flow.

Zimmermann, Robert; Bourgoin, Mickael; Volk, Romain; Pumir, Alain; Pinton, Jean-François

2010-01-01T23:59:59.000Z

436

Formation and evolution of interstellar filaments; Hints from velocity dispersion measurements  

E-Print Network (OSTI)

We investigate the gas velocity dispersions of a sample of filaments recently detected as part of the Herschel Gould Belt Survey in the IC5146, Aquila, and Polaris interstellar clouds. To measure these velocity dispersions, we use 13CO, C18O, and N2H+ line observations obtained with the IRAM 30m telescope. Correlating our velocity dispersion measurements with the filament column densities derived from Herschel data, we show that interstellar filaments can be divided into two regimes: thermally subcritical filaments, which have transonic velocity dispersions (c_s ~dispersions scaling roughly as the square root of column density (\\sigma_tot ~ \\Sigma^0.5), and are self-gravitating. The higher velocity dispersions of supercritical filaments may not directly arise from supersonic interstellar turbulence but may be driven by gravitational contraction/accretion...

Arzoumanian, Doris; Peretto, Nicolas; Konyves, Vera

2013-01-01T23:59:59.000Z

437

Velocity Measurements at Three Fish Screening Facilities in the Yakima Basin, Washington : Summer 1989 Annual Report.  

DOE Green Energy (OSTI)

The Pacific Northwest Laboratory (PNL) measured the velocity conditions at three fish screening facilities in the Yakima River Basin: Wapato, Chandler, and Easton Screens. The measurement objectives were different at the three screens. At Wapato, approach and sweep velocities were measured to evaluate the effect of rearing pens in the screen forebay. A complete survey was performed at the Chandler Screens. At Easton, velocity was measured behind the screens to provide information for the installation of porosity boards to balance flow through the screens. Salmon-rearing pens used at the Wapato Canal had a minimal effect on the magnitude of approach and sweep velocities at the face of the drum screens, although the pens caused increased turbulence and variability in water velocities. The net pens did not appear to affect flows through the three fish bypasses. 8 refs., 17 figs., 5 tabs.

Abernethy, C. Scott; Neitzel, Duane A.; Lusty, E. William

1990-09-01T23:59:59.000Z

438

Unitaxial constant velocity microactuator  

SciTech Connect

A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-manometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment.

McIntyre, Timothy J. (Knoxville, TN)

1994-01-01T23:59:59.000Z

439

Velocity and density spectra of the Small Magellanic Cloud  

E-Print Network (OSTI)

This paper reports results on the statistical analysis of HI turbulence in the Small Magellanic Cloud (SMC). We use 21 cm channel maps, obtained with the Australia Telescope Compact Array and the Parkes telescope, and analyze the spectrum of observed intensity fluctuations as a function of the velocity slice thickness. We confirm predictions by Lazarian & Pogosyan (2000) on the change of the power law index and establish the spectra of 3-D density and velocity. The obtained spectral indices, -3.3 and -3.4, are slightly more shallow than the predictions for the Kolmogorov spectrum. This contrasts to the predictions for the shock-type spectra that are steeper than the Kolmogorov one. The nature of the energy injection in the SMC is unclear as no distinct energy injection scales are observed up to the entire scale of the SMC.

S. Stanimirovi?; A. Lazarian

2001-02-11T23:59:59.000Z

440

Wave Energy  

Energy.gov (U.S. Department of Energy (DOE))

Wave energy technologies extract energy directly from surface waves or from pressure fluctuations below the surface. Renewable energy analysts believe there is enough energy in ocean waves to provide up to 2 terawatts of electricity. (A terawatt is equal to a trillion watts.)

Note: This page contains sample records for the topic "turbulence velocity wave" 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

OTRC Wave Basin | Open Energy Information  

Open Energy Info (EERE)

OTRC Wave Basin OTRC Wave Basin Jump to: navigation, search Basic Specifications Facility Name OTRC Wave Basin Overseeing Organization Texas A&M (OTRC) Hydrodynamic Testing Facility Type Wave Basin Length(m) 45.7 Beam(m) 30.5 Depth(m) 5.8 Water Type Freshwater Cost(per day) $300/hour (excluding labor) Special Physical Features 4.6m wide x 9.1m long x 16.8m deep pit with adjustable depth floor in test area Towing Capabilities Towing Capabilities Yes Maximum Velocity(m/s) 0.6 Length of Effective Tow(m) 27.4 Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.9 Maximum Wave Height(m) at Wave Period(s) 4.0 Maximum Wave Length(m) 25 Wave Period Range(s) 4.0 Current Velocity Range(m/s) 0.6 Programmable Wavemaking Yes Wavemaking Description GEDAP 3D wave generation software, 48 hinged flap wave generator

442

Turbulent Kinetic Energy Budgets over Mountainous Terrain  

Science Conference Proceedings (OSTI)

The objective of this study is to describe the characteristics of the airflow and turbulence structure over mountainous terrain. Turbulent characteristics of the airflow were measured using well-instrumented aircraft. The shear, buoyancy, ...

Theodore S. Karacostas; John D. Marwitz

1980-02-01T23:59:59.000Z

443

Turbulent Mixing in Stably Stratified Shear Flows  

Science Conference Proceedings (OSTI)

Vertical mixing of momentum and heat is investigated in turbulent stratified shear flows. It is assumed that the flow has uniform shear and stratification with homogeneous turbulence and that an equilibrium is reached between kinetic and ...

U. Schumann; T. Gerz

1995-01-01T23:59:59.000Z

444

The Canopy Horizontal Array Turbulence Study  

Science Conference Proceedings (OSTI)

The Canopy Horizontal Array Turbulence Study (CHATS) took place in spring 2007 and is the third in the series of Horizontal Array Turbulence Study (HATS) experiments. The HATS experiments have been instrumental in testing and developing subfilterscale (...

Edward G. Patton; Thomas W. Horst; Peter P. Sullivan; Donald H. Lenschow; Steven P. Oncley; William O. J. Brown; Sean P. Burns; Alex B. Guenther; Andreas Held; Thomas Karl; Shane D. Mayor; Luciana V. Rizzo; Scott M. Spuler; Jielun Sun; Andrew A. Turnipseed; Eugene J. Allwine; Steven L. Edburg; Brian K. Lamb; Roni Avissar; Ronald J. Calhoun; Jan Kleissl; William J. Massman; Kyaw Tha Paw U; Jeffrey C. Weil

2011-05-01T23:59:59.000Z

445

Effects of Atmospheric Turbulence on Ballistic Testing  

Science Conference Proceedings (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

446

Technique for the experimental estimation of nonlinear energy transfer in fully developed turbulence  

Science Conference Proceedings (OSTI)

A new procedure for calculating the nonlinear energy transfer and linear growth/damping rate of fully developed turbulence is derived. It avoids the unphysically large damping rates typically obtained using the predecessor method of Ritz [Ch. P. Ritz, E. J. Powers, and R. D. Bengtson, Phys. Fluids B {bold 1}, 153 (1989)]. It enforces stationarity of the turbulence to reduce the effects of noise and fluctuations not described by the basic governing equation, and includes the fourth-order moment to avoid the closure approximation. The new procedure has been implemented and tested on simulated, fully developed two-dimensional (2-D) turbulence data from a 2-D trapped-particle fluid code, and has been shown to give excellent reconstructions of the input growth rate and nonlinear coupling coefficients with good noise rejection. However, in the experimentally important case where only a one-dimensional (1-D) averaged representation of the underlying 2-D turbulence is available, this technique does not, in general, give acceptable results. A new 1-D algorithm has thus been developed for analysis of 1-D measurements of intrinsically 2-D turbulence. This new 1-D algorithm includes the nonresonant wave numbers in calculating the bispectra, and generally gives useful results when the width of the radial wave number spectrum is comparable to or less than that of the poloidal spectrum. {copyright} {ital 1996 American Institute of Physics.}

Kim, J.S.; Durst, R.D.; Fonck, R.J. [Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Fernandez, E.; Ware, A.; Terry, P.W. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)

1996-11-01T23:59:59.000Z

447

Seismic Velocity And Attenuation Structure Of The Geysers Geothermal Field,  

Open Energy Info (EERE)

Velocity And Attenuation Structure Of The Geysers Geothermal Field, Velocity And Attenuation Structure Of The Geysers Geothermal Field, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Seismic Velocity And Attenuation Structure Of The Geysers Geothermal Field, California Details Activities (1) Areas (1) Regions (0) Abstract: The Geysers geothermal field is located in northern California and is one of the world's largest producers of electricity from geothermal energy. A key resource management issue at this field is the distribution of fluid in the matrix of the reservoir rock. In this paper, we interpret seismic compressional-wave velocity and quality quotient (Q) data at The Geysers in terms of the geologic structure and fluid saturation in the reservoir. Our data consist of waveforms from approximately 300

448

Ship Waves and Lee Waves  

Science Conference Proceedings (OSTI)

Three-dimensional internal trapped lee wave modes produced by an isolated obstacle in a stratified fluid are shown to have dynamics analogous to surface ship waves on water of finite depth. Two models which allow for vertical trapping of wave ...

R. D. Sharman; M. G. Wurtele

1983-02-01T23:59:59.000Z

449

Progress in sub-grid scale modeling of shock-turbulence interaction  

DOE Green Energy (OSTI)

The authors report on progress in the development of sub grid scale (SGS) closure relationships for the unresolved motion scales in compressible large eddy simulations (LES). At present they are refining the SGS model and overall LES procedure to include: a linearized viscoelastic model for finite thickness shock distortions and shocked turbulence field response; multiple scale asymptotic considerations to improve predictions of average near-wall surface behavior; and a spectral statistical model simulating the effects of high wave number stochastic feed-back from the unresolved SGS nonlinear motion influences on the explicitly resolved grid scale motions. Predicted amplification levels, modal energy partition, shock translational to turbulence kinetic energy transfer, and viscoelastic spatio-temporal response of turbulence to shock interaction are examined in comparison with available experimental evidence. Supplemental hypersonic compressible turbulence experimental information is developed from sub nanosecond interval pulsed shadowgraph evidence of laser impulse generated hypervelocity shocks interacting with intense, previously developed and carefully characterized initial turbulence. Accurate description of the influence of shock-turbulence interactions is vital for predicting their influence on: Supersonic/hypersonic flow field analysis, aerodynamic design, and aerostructural materials selection. Practical applications also include interior supersonic combustion analysis and combustion chamber design. It is also the essential foundation for accurately predicting the development and evolution of flow-field generated thermal and electromagnetic radiation important to hypersonic flight vehicle survivability, detection and communication.

Buckingham, A.C. [Lawrence Livermore National Lab., CA (United States). Center for Advanced Fluid Dynamics Applications; Grun, J. [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.

1994-12-01T23:59:59.000Z

450

Midplane sedimentation of large solid bodies in turbulent protoplanetary discs  

E-Print Network (OSTI)

We study the vertical settling of solid bodies in a turbulent protoplanetary disc. We consider the situation when the coupling to the gas is weak or equivalently when the particle stopping time tau_{st} due to friction with the gas is long compared to the orbital timescale Omega^{-1}. An analytical model, which takes into account the stochastic nature of the sedimentation process using a Fokker-Planck equation for the particle distribution function in phase space, is used to obtain the vertical scale height of the solid layer as a function of the vertical component of the turbulent gas velocity correlation function and the particle stopping time. This is found to be of the same form as the relation obtained for strongly coupled particles in previous work. We compare the predictions of this model with results obtained from local shearing box MHD simulations of solid particles embedded in a vertically stratified disc in which there is turbulence driven by the MRI. We find that the ratio of the dust disc thickne...

Carballido, A; Papaloizou, J

2006-01-01T23:59:59.000Z

451

Stability Regimes of Turbulent Nitrogen-Diluted Hydrogen Jet Flames  

SciTech Connect

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

452

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 and, unexpectedly, we also find a dependence upon 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

2013-10-21T23:59:59.000Z

453

MAGNETIC METHOD FOR PRODUCING HIGH VELOCITY SHOCK WAVES IN GASES  

DOE Patents (OSTI)

A device is described for producing high-energy plasmas comprising a tapered shock tube of dielectric material and having a closed small end, an exceedingly low-inductance coll supported about and axially aligned with the small end of the tapered tube. an elongated multiturn coil supported upon the remninder of the exterior wall of the shock tube. a potential source and switch connected in series with the low-inductance coil, a potential source and switch connected in series with the elongated coil, means for hermetically sealing the large end of the tube, means for purging the tube of gases, and means for admitting a selected gas into the shock tube.

Josephson, V.

1960-01-26T23:59:59.000Z

454

APPARATUS FOR PRODUCING HIGH VELOCITY SHOCK WAVES IN GASES  

DOE Patents (OSTI)

>A device for producing a high-energy ionized gas region comprises an evacuated tapered insulating vessel and a substantially hemispherical insulating cap hermetically affixed to the large end of the vessel, an annular electrode having a diameter equal to and supported in the interior wall of the vessel at the large end and having a conductive portion inside the vessel, a second electrode supported at the small end of the vessel, means connected to the vessel for introducing a selected gas therein, a source of high potential having two poles. means for connecting one pole of the high potential source to the annular electrode, and means for connecting the other pole of the potential source to the second electrode.

Scott, F.R.; Josephson, V.

1960-02-01T23:59:59.000Z

455

Compressible Turbulence and Interactions with Shock Waves and...  

NLE Websites -- All DOE Office Websites (Extended Search)

Why it Matters: Shockturbulence interaction is a fundamental phenomenon in fluid mechanics that occurs in a wide range of interesting problems in various disciplines,...

456

Acoustic Waves in the Turbulent Atmosphere: A Review  

Science Conference Proceedings (OSTI)

The subject of atmospheric acoustics and its role in atmospheric research and in development of modern methods of ground-based remote sensing of the atmosphere are outlined. A historical overview of investigations of the effect of atmospheric ...

M. A. Kallistratova

2002-08-01T23:59:59.000Z

457

DeFrees Small Wave Basin | Open Energy Information  

Open Energy Info (EERE)

Wave Basin Wave Basin Jump to: navigation, search Basic Specifications Facility Name DeFrees Small Wave Basin Overseeing Organization Cornell University Hydrodynamics Hydrodynamic Testing Facility Type Wave Basin Length(m) 15.0 Beam(m) 0.8 Depth(m) 0.9 Water Type Freshwater Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.3 Maximum Wave Height(m) at Wave Period(s) 3.0 Maximum Wave Length(m) 30 Wave Period Range(s) 3.0 Current Velocity Range(m/s) 0.0 Programmable Wavemaking Yes Wavemaking Description Computer controlled hydraulic paddle, arbitrary wave shape possible Wave Direction Uni-Directional Simulated Beach Yes Description of Beach 1:10 sloping glass with dissipative horsehair covering if needed

458

Derivation of transformation equations for the parameters that characterize a plane acoustic wave without using phase invariance and Lorentz-Einstein transformation  

E-Print Network (OSTI)

We show that the transformation equations for the parameters that characterize a plane acoustic wave: period, (frequency), wave vector, wave length and phase velocity can be derived without using phase invariance and Lorentz-Einstein transformation

Bernhard Rothenstein

2005-06-20T23:59:59.000Z

459

Is there Lower Limit to Velocity or Velocity Change?  

E-Print Network (OSTI)

Here we explore the possibility of a lower limit to velocity or velocity change which is 20 orders of magnitude smaller than the speed of light and explore the various observable signatures including those in cosmic rays and gamma ray bursts.

B. N. Sreenath; Kenath Arun; C. Sivaram

2012-09-17T23:59:59.000Z

460

Wind Forced Internal Waves in the North Pacific and Sargasso Sea  

Science Conference Proceedings (OSTI)

The three-dimensional structure of the near-inertial frequency internal wave field was measured at two open ocean sites using expendable velocity profilers. Both wave fields appear to be dominantly wind forced although their vertical structure ...

Eric A. D'Asaro

1984-04-01T23:59:59.000Z

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