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1

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...

2

Wind turbulence characterization for wind energy development  

DOE Green Energy (OSTI)

As part of its support of the US Department of Energy's (DOE's) Federal Wind Energy Program, the Pacific Northwest Laboratory (PNL) has initiated an effort to work jointly with the wind energy community to characterize wind turbulence in a variety of complex terrains at existing or potential sites of wind turbine installation. Five turbulence characterization systems were assembled and installed at four sites in the Tehachapi Pass in California, and one in the Green Mountains near Manchester, Vermont. Data processing and analyses techniques were developed to allow observational analyses of the turbulent structure; this analysis complements the more traditional statistical and spectral analyses. Preliminary results of the observational analyses, in the rotating framework or a wind turbine blade, show that the turbulence at a site can have two major components: (1) engulfing eddies larger than the rotor, and (2) fluctuating shear due to eddies smaller than the rotor disk. Comparison of the time series depicting these quantities at two sites showed that the turbulence intensity (the commonly used descriptor of turbulence) did not adequately characterize the turbulence at these sites. 9 refs., 10 figs.,

Wendell, L.L.; Gower, G.L.; Morris, V.R.; Tomich, S.D.

1991-09-01T23:59:59.000Z

3

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

4

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

5

Supercomputers Capture Turbulence in the Solar Wind  

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

Provide Web Site Feedback: info@es.net Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space...

6

Wind Tunnel Study of Turbulent Flow Structure in the Convective Boundary Layer Capped by a Temperature Inversion  

Science Conference Proceedings (OSTI)

Experiments on simulating the atmospheric convective boundary layer (CBL), capped by a temperature inversion and affected by surface shear, were carried out in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources,...

Evgeni Fedorovich; Rolf Kaiser; Matthias Rau; Erich Plate

1996-05-01T23:59:59.000Z

7

k-? turbulence modeling for a wind turbine.  

E-Print Network (OSTI)

?? In this report we discuss the use of k-? RANS (Reynolds-averaged Navier-Stokes equations) turbulence model for wind turbine applications. This model has been implemented… (more)

EREK, ERMAN

2011-01-01T23:59:59.000Z

8

Supercomputers Capture Turbulence in the Solar Wind  

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

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

9

Turbulent Spectra in the Solar Wind Plasma  

E-Print Network (OSTI)

Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of -5/3 over six decades in wavenumber space. A similar turbulent density spectrum in the solar wind plasma has been reported. The energy transfer process in the magnetized solar wind plasma over such extended length-scales remains an unresolved paradox of modern turbulence theories raising the especially intriguing question of how a compressible magnetized solar wind exhibits a turbulent spectrum that is a characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfv\\'enic, supersonic and strongly magnetized plasma. It is shown that the observed Kolmogorov-like (-5/3) spectrum can develop in the solar wind plasma by supersonic plasma motions that dissipate into highly subsonic motion that passively ...

Shaikh, Dastgeer

2009-01-01T23:59:59.000Z

10

Supercomputers Capture Turbulence in the Solar Wind  

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

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

11

Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind  

E-Print Network (OSTI)

Anisotropic MHD Turbulence in the Interstellar Medium and Solar Wind C. S. Ng Center for Magnetic (MHD) turbulence Observations in ISM and solar wind · Anisotropy due to magnetic field · Electron MHD turbulence #12;Interstellar turbulence From Cordes (1999) Observation: power law relation between electron

Ng, Chung-Sang

12

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

13

Turbulent Density Spectrum in Solar Wind Plasma  

E-Print Network (OSTI)

The density fluctuation spectrum in the solar wind reveals a Kolmogorov-like scaling with a spectral slope of -5/3 in wavenumber space. The energy transfer process in the magnetized solar wind, characterized typically by MHD turbulence, over extended length-scales remains an unresolved paradox of modern turbulence theories, raising the question of how a compressible magnetofluid exhibits a turbulent spectrum that is characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfv\\'enic, supersonic and strongly magnetized plasma fluid. It is shown that a Kolmogorov-like density spectrum can develop by plasma motions that are dominated by Alfv\\'enic cascades whereas compressive modes are dissipated.

Shaikh, Dastgeer

2009-01-01T23:59:59.000Z

14

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

15

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

16

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

17

Identification of Wind Turbine Response to Turbulent Inflow Structures: Preprint  

DOE Green Energy (OSTI)

The National Renewable Energy Laboratory conducted an experiment to obtain detailed wind measurements and corresponding wind turbine measurements in order to establish a causal relationship between coherent turbulent structures and wind turbine blade fatigue loads. Data were collected for one entire wind season from October 2000 to May 2001. During this period, the wind turbine operated under atmospheric conditions that support the formation of coherent turbulent structures 31% of the time. Using the equivalent fatigue load parameter as a measure of wind turbine blade fatigue and using statistical measures of the turbulent fluctuations of the wind, general correlation between the turbulence and the wind turbine response is shown. Direct correlation cannot be resolved with 10-minute statistics for several reasons. Multiple turbulent structures can exist within a 10-minute record, and the equivalent fatigue load parameter is essentially a 10-minute statistic that cannot estimate turbine response to individual turbulent structures. Large-magnitude turbulent fluctuations in the form of instantaneous Reynolds stresses do not necessarily correspond directly to large-magnitude blade root moment amplitudes. Thus, additional work must be done to quantify the negative turbine response and to correlate this response to turbulent inflow parameters over time scales less than 10 minutes.

Hand, M. M.; Kelley, N. D.; Balas, M. J.

2003-06-01T23:59:59.000Z

18

Wind Scanner: A full-scale Laser Facility for Wind and Turbulence Measurements around large Wind Turbines  

E-Print Network (OSTI)

Wind Scanner: A full-scale Laser Facility for Wind and Turbulence Measurements around large Wind Turbines Torben Mikkelsen, Jakob Mann and Michael Courtney Wind Energy Department, Risø National Laboratory:Torben.Mikkelsen@Risoe.dk Summary RIS� DTU has started to build a newly designed laser-based lidar scanning facility for remote wind

19

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

20

Impact of Coherent Turbulence on Wind Turbine Aeroelastic Response and Its Simulation: Preprint  

DOE Green Energy (OSTI)

In this paper, we present a brief overview of our recent research results regarding the impact of organized or coherent inflow turbulence on the dynamic response of operating wind turbines. Previous field experimentation has demonstrated that the greatest structural fatigue damage tends to occur during the nighttime hours from coherent turbulence that develops in the stable, nocturnal atmospheric boundary layer. We have found that under such conditions, intense vertical wind shear and temperature gradients create resonant flow fields that are capable of imparting short-period loading and vibrational energy as wind turbine rotor blades pass through regions of organized or coherent turbulence. This energy is subsequently propagated throughout the remainder of the structure, where it is often locally dissipated. We also briefly discuss our recent progress in developing a numerical simulation that includes such coherent inflow conditions that can be used to excite wind turbine design codes.

Kelley, N. D.; Jonkman, B. J.; Scott, G. N.; Bialasiewicz, J. T.; Redmond, L. S.

2005-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

22

Generalized similarity in finite range solar wind magnetohydrodynamic turbulence  

E-Print Network (OSTI)

Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. ULYSSES spacecraft solar polar passes at solar minimum provide \\textit{in situ} observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterises this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum -with turbulent fluctuations down by a factor of $\\sim 2$ in power- provides a test of this invariance.

Chapman, S C

2009-01-01T23:59:59.000Z

23

THE TURBULENT CASCADE AND PROTON HEATING IN THE SOLAR WIND DURING SOLAR MINIMUM  

Science Conference Proceedings (OSTI)

The recently protracted solar minimum provided years of interplanetary data that were largely absent in any association with observed large-scale transient behavior on the Sun. With large-scale shear at 1 AU generally isolated to corotating interaction regions, it is reasonable to ask whether the solar wind is significantly turbulent at this time. We perform a series of third-moment analyses using data from the Advanced Composition Explorer. We show that the solar wind at 1 AU is just as turbulent as at any other time in the solar cycle. Specifically, the turbulent cascade of energy scales in the same manner proportional to the product of wind speed and temperature. Energy cascade rates during solar minimum average a factor of 2-4 higher than during solar maximum, but we contend that this is likely the result of having a different admixture of high-latitude sources.

Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH (United States); Stawarz, Joshua E. [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, CA (United States); Forman, Miriam A., E-mail: jtu46@wildcats.unh.edu, E-mail: Charles.Smith@unh.edu, E-mail: Bernie.Vasquez@unh.edu, E-mail: Joshua.Stawarz@Colorado.edu, E-mail: Miriam.Forman@sunysb.edu [Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY (United States)

2012-08-01T23:59:59.000Z

24

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

25

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

26

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

27

A Tree Swaying in a Turbulent Wind: A Scaling Analysis  

E-Print Network (OSTI)

A tentative scaling theory is presented of a tree swaying in a turbulent wind. It is argued that the turbulence of the air within the crown is in the inertial regime, An eddy causes a dynamic bending response of the branches according to a time criterion. The resulting expression for the penetration depth of the wind yields an exponent which is in agreement with that pertaining to the morphology of the tree branches. An energy criterion shows that the dynamics of the branches is basically passive. The possibility of hydrodynamic screening by the leaves is discussed.

Theo Odijk

2013-05-29T23:59:59.000Z

28

Estimation of turbulence level and scale for wind turbine applications  

DOE Green Energy (OSTI)

A simplified method is presented for estimating onsite turbulence variance within the wind turbine layer for horizontal wind speed. The method is based principally on estimating the probability distribution of wind speed and assigning a variance to each mean wind speed based on surface roughness estimates. The model is not proposed as an alternative to onsite measurement and analysis, but rather as an adjunct to such a program. A revision of the Kaimal neutral u-component spectrum is suggested to apply to the mix of the stabilities occurring during operational winds. Values of integral length scale calculated from data analysis are shown to contradict the length scale model implicit in turbulence power spectra. Also, these calculated values are shown to be extremely sensitive to the length of the time series and the detrending method used. The analysis and modeling are extended to the rotational frame of reference for a horizontal-axis wind turbine by modeling the ratios of harmonic spike variances (1P, 2P, etc.) in the rotational spectrum to the Eulerian turbulence variance. 15 refs., 11 figs., 3 tabs.

Powell, D.C.

1988-11-01T23:59:59.000Z

29

Using a new characterization of turbulent wind for accurate correlation of wind turbine response with wind speed  

SciTech Connect

The turbulence encountered by a point on a rotating wind turbine blade has characteristics that in some important respects are different from those measured by a stationary anemometer. The conventional one-peaked continuous spectrum becomes, broadly, a two-peaked spectrum that in addition contains a set of narrow-band spikes of turbulence energy, one centered on the frequency of rotor rotation and the others centered on multiples of that frequency. The rotational sampling effect on wind spectra is quantified using measurements of wind velocity by anemometers on stationary crosswind circular arrays. Characteristics of fluctuating wind are compared to measured fluctuations of bending moments of the rotor blades and power output fluctuations of a horizontal-axis wind turbine at the same site. The wind characteristics and the correlations between wind fluctuations and wind turbine fluctuations provide a basis for improving turbine design, siting, and control. 6 refs., 11 figs., 1 tab.

Connell, J.R.; George, R.L.

1987-09-01T23:59:59.000Z

30

Turbulent heating of the corona and solar wind: the heliospheric  

E-Print Network (OSTI)

of telegraph services - Once per 500 years (ice cores) - Solar-terrestrial connection - Interplanetary space of radiators - Dust environment - Cp/Cg problems - Solar panels and power #12;Solar Probe Plus 2018 launch 35Turbulent heating of the corona and solar wind: the heliospheric dark energy problem Stuart D. Bale

31

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

32

Modelling the Vertical Wind Speed and Turbulence Intensity Profiles at Prospective Offshore Wind Farm Sites  

E-Print Network (OSTI)

Monin-Obukhov theory predicts the well-known log-linear form of the vertical wind speed profile. A turbulence intensity profile can be estimated from this by assuming that the standard deviation of the wind speed is proportional to the friction velocity. Two parameters, namely the aerodynamic surface roughness length and the MoninObukhov length, are than needed to predict the vertical wind speed and turbulence intensity profiles from a measurement at one height. Different models to estimate these parameters for conditions important for offshore wind energy utilisation are compared and tested: Four models for the surface roughness and three methods to derive the Monin-Obukov-length from measurements. They have been tested with data from the offshore field measurement Rdsand by extrapolating the measured 10 m wind speed to 50 m height and comparing it with the measured 50 m wind speed.

Bernhard Lange; Søren Larsen; Jørgen Højstrup; Rebecca Barthelmie; Ulrich Focken

2002-01-01T23:59:59.000Z

33

Measurements of Wind and Turbulence Profiles with Scanning Doppler Lidar for Wind Energy Applications  

SciTech Connect

High-quality profiles of mean and turbulent statistics of the wind field upstream of a wind farm can be produced using a scanning Doppler lidar. Careful corrections for the spatial filtering of the wind field by the lidar pulse produce turbulence estimates equivalent to point sensors but with the added advantage of a larger sampling volume to increase the statistical accuracy of the estimates. For a well-designed lidar system, this permits accurate estimates of the key turbulent statistics over various subdomains and with sufficiently short observation times to monitor rapid changes in conditions. These features may be ideally suited for optimal operation of wind farms and also for improved resource assessment of potential sites.

Frehlich, R.; Kelley, N.

2008-03-01T23:59:59.000Z

34

Remote Measurement of Turbulent Wind Spectra by Heterodyne DopplerLidar Technique  

Science Conference Proceedings (OSTI)

Heterodyne Doppler lidars (HDLs) are used to monitor atmospheric wind field and wind turbulence at remote distance. This last application calls for the derivation of wind spectra, which can be characterized by the dissipation rate and the ?-...

Philippe Drobinski; Alain M. Dabas; Pierre H. Flamant

2000-12-01T23:59:59.000Z

35

Parallel Electric Field Spectrum of Solar Wind Turbulence  

E-Print Network (OSTI)

By searching through more than 10 satellite-years of THEMIS and Cluster data, three reliable examples of parallel electric field turbulence in the undisturbed solar wind have been found. The perpendicular and parallel electric field spectra in these examples have similar shapes and amplitudes, even at large scales (frequencies below the ion gyroscale) where Alfvenic turbulence with no parallel electric field component is thought to dominate. The spectra of the parallel electric field fluctuations are power laws with exponents near -5/3 below the ion scales (~ 0.1 Hz), and with a flattening of the spectrum in the vicinity of this frequency. At small scales (above a few Hz), the spectra are steeper than -5/3 with values in the range of -2.1 to -2.8. These steeper slopes are consistent with expectations for kinetic Alfven turbulence, although their amplitude relative to the perpendicular fluctuations is larger than expected.

Mozer, F S

2013-01-01T23:59:59.000Z

36

Solar Wind Turbulence A Study of Corotating Interaction Regions at 1 AU  

E-Print Network (OSTI)

Solar Wind Turbulence A Study of Corotating Interaction Regions at 1 AU Je rey A. Tessein Department of Physics University of New Hampshire Durham, NH 03824 May 15, 2009 #12;Abstract The solar wind's rotation and the variability in the source of the solar wind, fast moving wind can crash into slow wind

New Hampshire, University of

37

Wind Shear and Turbulence Profiles at Elevated Heights: Great Lakes and Midwest Sites (Poster)  

DOE Green Energy (OSTI)

Analyzed wind resource characteristics at elevated heights (50 m-200+m) incuding shear and turbulence profiles for some areas of the Great Lakes and M idwest sites.

Elliott, D.; Schwartz, M.; Scott, G.

2009-05-01T23:59:59.000Z

38

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

39

Comparison of Mean Wind Speeds and Turbulence at a Coastal Site and Offshore Location  

Science Conference Proceedings (OSTI)

Observations of mean wind speed and longitudinal turbulence at a height of 8 m over the Atlantic ocean, 5 km off Long Island, New York, were compared with simultaneous observations at the beach. Results were grouped into wind direction classes ...

S. SethuRaman; G. S. Raynor

1980-01-01T23:59:59.000Z

40

Study of Radiative and Turbulent Processes in the Stable Boundary Layer under Weak Wind Conditions  

Science Conference Proceedings (OSTI)

The role of radiation and turbulence was studied in a weak wind nocturnal inversion layer using a one-dimensional model. In contrast to a strong wind stable boundary layer where cooling within the surface inversion layer is dominated by ...

S. G. Gopalakrishnan; Maithili Sharan; R. T. McNider; M. P. Singh

1998-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

User's guide for a personal computer model of turbulence at a wind turbine rotor  

DOE Green Energy (OSTI)

This document is primarily (1) a user's guide for the personal computer (PC) version of the code for the PNL computational model of the rotationally sampled wind speed (RODASIM11) and (2) a brief guide to the growing literature on the subject of rotationally sampled turbulence, from which the model is derived. The model generates values of turbulence experienced by single points fixed in the rotating frame of reference of an arbitrary wind turbine blade. The character of the turbulence depends on the specification of mean wind speed, the variance of turbulence, the crosswind and along-wind integral scales of turbulence, mean wind shear, and the hub height, radius, and angular speed of rotation of any point at which wind fluctuation is to be calculated. 13 refs., 4 figs., 4 tabs.

Connell, J.R.; Powell, D.C.; Gower, G.L.

1989-08-01T23:59:59.000Z

42

THREE-DIMENSIONAL STRUCTURE OF SOLAR WIND TURBULENCE  

SciTech Connect

We present a measurement of the scale-dependent, three-dimensional structure of the magnetic field fluctuations in inertial range solar wind turbulence with respect to a local, physically motivated coordinate system. The Alfvenic fluctuations are three-dimensionally anisotropic, with the sense of this anisotropy varying from large to small scales. At the outer scale, the magnetic field correlations are longest in the local fluctuation direction, consistent with Alfven waves. At the proton gyroscale, they are longest along the local mean field direction and shortest in the direction perpendicular to the local mean field and the local field fluctuation. The compressive fluctuations are highly elongated along the local mean field direction, although axially symmetric perpendicular to it. Their large anisotropy may explain why they are not heavily damped in the solar wind.

Chen, C. H. K.; Bale, S. D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Mallet, A.; Schekochihin, A. A. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP (United Kingdom); Horbury, T. S. [Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Wicks, R. T., E-mail: chen@ssl.berkeley.edu [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-10-20T23:59:59.000Z

43

Inflow Turbulence Energy and its Spatial Distribution on a Wind Turbine  

E-Print Network (OSTI)

Inflow Turbulence Energy and its Spatial Distribution on a Wind Turbine Christopher Wright Dr caused the most variability of turbulence energy while high wind shear exponents caused the least........................................................................................................................ 18 #12;Completion report on our project to empirically evaluate energy distribution in unique spatial

Manuel, Lance

44

THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF THE SOLAR WIND INCLUDING PICKUP PROTONS AND TURBULENCE TRANSPORT  

Science Conference Proceedings (OSTI)

To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons. We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 Degree-Sign -90 Degree-Sign and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.

Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 673, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-07-20T23:59:59.000Z

45

Turbulence Patch Identification in Potential Density or Temperature Profiles  

Science Conference Proceedings (OSTI)

The Thorpe analysis is a recognized method used to identify and characterize turbulent regions within stably stratified fluids. By comparing an observed profile of potential temperature or potential density to a reference profile obtained by ...

Richard Wilson; Hubert Luce; Francis Dalaudier; Jacques Lefrère

2010-06-01T23:59:59.000Z

46

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

47

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

48

Spaced-Antenna Interferometry to Measure Crossbeam Wind, Shear, and Turbulence: Theory and Formulation  

Science Conference Proceedings (OSTI)

The theory of measuring crossbeam wind, shear, and turbulence within the radar’s resolution volume V6 is described. Spaced-antenna weather radar interferometry is formulated for such measurements using phased-array weather radar. The formulation ...

Guifu Zhang; Richard J. Doviak

2007-05-01T23:59:59.000Z

49

A Volume-Imaging Radar Wind Profiler for Atmospheric Boundary Layer Turbulence Studies  

Science Conference Proceedings (OSTI)

This paper describes the turbulent eddy profiler (TEP), a volume-imaging, UHF radar wind profiler designed for clear-air measurements in the atmospheric boundary layer on scales comparable to grid cell sizes of large eddy simulation models. TEP ...

James B. Mead; Geoffrey Hopcraft; Stephen J. Frasier; Brian D. Pollard; Christopher D. Cherry; Daniel H. Schaubert; Robert E. McIntosh

1998-08-01T23:59:59.000Z

50

The Relationships among Wind, Horizontal Pressure Gradient, and Turbulent Momentum Transport during CASES-99  

Science Conference Proceedings (OSTI)

Relationships among the horizontal pressure gradient, the Coriolis force, and the vertical momentum transport by turbulent fluxes are investigated using data collected from the Cooperative Atmosphere-Surface Exchange Study in 1999 (CASES99). Wind ...

Jielun Sun; Donald H. Lenschow; Larry Mahrt; Carmen Nappo

51

TURBULENCE-DRIVEN POLAR WINDS FROM T TAURI STARS ENERGIZED BY MAGNETOSPHERIC ACCRETION  

E-Print Network (OSTI)

Pre-main-sequence stars are observed to be surrounded by both accretion flows and some kind of wind or jetlike outflow. Recent work by Matt and Pudritz has suggested that if classical T Tauri stars exhibit stellar winds with massloss rates about 0.1 times their accretion rates, the wind can carry away enough angular momentum to keep the stars from being spun up unrealistically by accretion. This paper presents a preliminary set of theoretical models of accretiondriven winds from the polar regions of T Tauri stars. These models are based on recently published self-consistent simulations of the Sun’s coronal heating and wind acceleration. In addition to the convection-driven MHD turbulence (which dominates in the solar case), we add another source of wave energy at the photosphere that is driven by the impact of plasma in neighboring flux tubes undergoing magnetospheric accretion. This added energy, determined quantitatively from the far-field theory of MHD wave generation, is sufficient to produce T TauriYlike mass-loss rates of at least 0.01 times the accretion rate. While still about an order of magnitude below the level required for efficient angular momentum removal, these are the first self-consistent models of T Tauri winds that agree reasonably well with a range of observational mass-loss constraints. The youngest modeled stellar winds are supported by Alfvén wave pressure, they have low temperatures (‘‘extended chromospheres’’), and they are likely to be unstable to the formation of counterpropagating shocks and clumps far from the star.

Steven R. Cranmer

2008-01-01T23:59:59.000Z

52

Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence  

E-Print Network (OSTI)

We present a series of models for the plasma properties along open magnetic flux tubes rooted in solar coronal holes, streamers, and active regions. These models represent the first self-consistent solutions that combine: (1) chromospheric heating driven by an empirically guided acoustic wave spectrum, (2) coronal heating from Alfven waves that have been partially reflected, then damped by anisotropic turbulent cascade, and (3) solar wind acceleration from gradients of gas pressure, acoustic wave pressure, and Alfven wave pressure. The only input parameters are the photospheric lower boundary conditions for the waves and the radial dependence of the background magnetic field along the flux tube. For a single choice for the photospheric wave properties, our models produce a realistic range of slow and fast solar wind conditions by varying only the coronal magnetic field. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above the Parker critical point. As predicted by earlier studies, a larger coronal ``expansion factor'' gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. These models offer supporting evidence for the idea that coronal heating and solar wind acceleration (in open magnetic flux tubes) can occur as a result of wave dissipation and turbulent cascade. (abridged abstract)

Steven R. Cranmer; Adriaan A. van Ballegooijen; Richard J. Edgar

2007-03-13T23:59:59.000Z

53

Prediction of the Proton-to-Total Turbulent Heating in the Solar Wind  

E-Print Network (OSTI)

This paper employs a recent turbulent heating prescription to predict the ratio of proton-to-total heating due to the kinetic dissipation of Alfvenic turbulence as a function of heliocentric distance. Comparing to a recent empirical estimate for this turbulent heating ratio in the high-speed solar wind, the prediction shows good agreement with the empirical estimate for R >~ 0.8 AU, but predicts less ion heating than the empirical estimate at smaller heliocentric radii. At these smaller radii, the turbulent heating prescription, calculated in the gyrokinetic limit, fails because the turbulent cascade is predicted to reach the proton cyclotron frequency before Landau damping terminates the cascade. These findings suggest that the turbulent cascade can reach the proton cyclotron frequency at R ~ 0.8 AU, this turbulent heating prescription contains all of the necessary physical mechanisms needed to reproduce the empirically estimated proton-to-total heating ratio.

Howes, G G

2011-01-01T23:59:59.000Z

54

On the Loss of Wind-Induced Near-Inertial Energy to Turbulent Mixing in the Upper Ocean  

E-Print Network (OSTI)

On the Loss of Wind-Induced Near-Inertial Energy to Turbulent Mixing in the Upper Ocean XIAOMING received 27 March 2009, in final form 23 June 2009) ABSTRACT Wind-induced near-inertial energy has been find that nearly 70% of the wind-induced near-inertial energy at the sea surface is lost to turbulent

Miami, University of

55

ENHANCED DISSIPATION RATE OF MAGNETIC FIELD IN STRIPED PULSAR WINDS BY THE EFFECT OF TURBULENCE  

SciTech Connect

In this paper, we report on turbulent acceleration of the dissipation of the magnetic field in the post-shock region of a Poynting flux-dominated flow, such as the Crab pulsar wind nebula. We have performed two-dimensional resistive relativistic magnetohydrodynamics simulations of subsonic turbulence driven by the Richtmyer-Meshkov instability at the shock fronts of the Poynting flux-dominated flows in pulsar winds. We find that turbulence stretches current sheets which substantially enhances the dissipation of the magnetic field, and that most of the initial magnetic field energy is dissipated within a few eddy-turnover times. We also develop a simple analytical model for turbulent dissipation of the magnetic field that agrees well with our simulations. The analytical model indicates that the dissipation rate does not depend on resistivity even in the small resistivity limit. Our findings can possibly alleviate the {sigma}-problem in the Crab pulsar wind nebulae.

Takamoto, Makoto [Department of Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Inoue, Tsuyoshi [Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku, Sagamihara 252-5258 (Japan); Inutsuka, Shu-ichiro, E-mail: takamoto@tap.scphys.kyoto-u.ac.jp, E-mail: inouety@phys.aoyama.ac.jp, E-mail: inutsuka@nagoya-u.jp [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

2012-08-10T23:59:59.000Z

56

Analysis of Wind and Turbulence Fields in a Region with Complex Orography  

Science Conference Proceedings (OSTI)

In a region of about 1000 km2 with complex orography, 1-h averages of wind and turbulence fields were analyzed over a period of 1 yr. It was shown that spatial homogeneity and temporal stationarity of the wind fields as well as the degree of ...

Waldemar Feller; Fritz Gassmann

1997-09-01T23:59:59.000Z

57

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

58

Propagation of Wind Energy into the Deep Ocean through a Fully Turbulent Mesoscale Eddy Field  

Science Conference Proceedings (OSTI)

The authors analyze the 3D propagation of wind-forced near-inertial motions in a fully turbulent mesoscale eddy field with a primitive equation numerical model. Although the wind stress is uniform, the near-inertial motion field quickly becomes ...

Eric Danioux; Patrice Klein; Pascal Rivière

2008-10-01T23:59:59.000Z

59

Theory of Equilibrium Temperatures in Radiative-Turbulent Atmospheres  

Science Conference Proceedings (OSTI)

We have developed a thermodynamic model for the determination of the temperature profile based on the balance of radiative and turbulent fluxes. In the context of a one-dimensional case, we show that the temperature field is governed by a first-...

Kuo-Nan Liou; Szu-Cheng S. Ou

1983-01-01T23:59:59.000Z

60

THE NEW WIND CHILL EQUIVALENT TEMPERATURE CHART  

Science Conference Proceedings (OSTI)

The formula used in the U.S. and Canada to express the combined effect of wind and low temperature on how cold it feels was changed in November 2001. Many had felt that the old formula for equivalent temperature, derived in the 1960s from Siple ...

Randall Osczevski; Maurice Bluestein

2005-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Remote Determination of Winds, Turbulence Spectra and Energy Dissipation Rates in the Boundary Layer from Lidar Measurements  

Science Conference Proceedings (OSTI)

Procedures are described for the analysis of lidar data to remotely measure 1) spectra of aerosol density fluctuations, 2) radial and transverse components of the mean wind and turbulent fluctuations of the transverse component of the wind ...

K. E. Kunkel; E. W. Eloranta; J. A. Weinman

1980-05-01T23:59:59.000Z

62

Scaling Laws of Turbulence and Heating of Fast SolarWind: The Role of Density Fluctuations  

E-Print Network (OSTI)

Incompressible and isotropic magnetohydrodynamic turbulence in plasms can be described by an exact relation for the energy flux through the scales. This Yaglom-like scaling law has been recently observed in the solar wind above the solar poles observed by the Ulysses spacecraft, where the turbulence is in an Alfv\\'enic state. An analogous phenomenological scaling law, suitably modified to take into account compressible fluctuations, is observed more frequently in the same dataset. Large scale density fluctuations, despite their low amplitude, play thus a crucial role in the basic scaling properties of turbulence. The turbulent cascade rate in the compressive case can moreover supply the energy dissipation needed to account for the local heating of the non-adiabatic solar wind.

Carbone, V; Sorriso-Valvo, L; Noullez, A; Bruno, R

2010-01-01T23:59:59.000Z

63

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

64

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

65

The turbulent cascade and proton heating in the solar wind during solar minimum  

Science Conference Proceedings (OSTI)

Solar wind measurements at 1 AU during the recent solar minimum and previous studies of solar maximum provide an opportunity to study the effects of the changing solar cycle on in situ heating. Our interest is to compare the levels of activity associated with turbulence and proton heating. Large-scale shears in the flow caused by transient activity are a source that drives turbulence that heats the solar wind, but as the solar cycle progresses the dynamics that drive the turbulence and heat the medium are likely to change. The application of third-moment theory to Advanced Composition Explorer (ACE) data gives the turbulent energy cascade rate which is not seen to vary with the solar cycle. Likewise, an empirical heating rate shows no significan changes in proton heating over the cycle.

Coburn, Jesse T.; Smith, Charles W.; Vasquez, Bernard J. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire (United States); Stawarz, Joshua E. [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, Colorado (United States); Forman, Miriam A. [Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York (United States)

2013-06-13T23:59:59.000Z

66

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

67

Electron and proton heating by solar wind turbulence  

E-Print Network (OSTI)

Previous formulations of heating and transport associated with strong magnetohydrodynamic (MHD) turbulence are generalized to incorporate separate internal energy equations for electrons and protons. Electron heat conduction is included. Energy is supplied by turbulent heating that affects both electrons and protons, and is exchanged between them via collisions. Comparison to available Ulysses data shows that a reasonable accounting for the data is provided when (i) the energy exchange timescale is very long and (ii) the deposition of heat due to turbulence is divided, with 60% going to proton heating and 40% into electron heating. Heat conduction, determined here by an empirical fit, plays a major role in describing the electron data.

Breech, B; Cranmer, S R; Kasper, J C; Oughton, S

2009-01-01T23:59:59.000Z

68

Electron geodesic acoustic modes in electron temperature gradient mode turbulence  

Science Conference Proceedings (OSTI)

In this work, the first demonstration of an electron branch of the geodesic acoustic mode (el-GAM) driven by electron temperature gradient (ETG) modes is presented. The work is based on a fluid description of the ETG mode retaining non-adiabatic ions and the dispersion relation for el-GAMs driven nonlinearly by ETG modes is derived. A new saturation mechanism for ETG turbulence through the interaction with el-GAMs is found, resulting in a significantly enhanced ETG turbulence saturation level compared to the mixing length estimate.

Anderson, Johan; Nordman, Hans [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Singh, Raghvendra; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

2012-08-15T23:59:59.000Z

69

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

70

Short wavelength ion temperature gradient turbulence  

Science Conference Proceedings (OSTI)

The ion temperature gradient (ITG) mode in the high wavenumber regime (k{sub y}{rho}{sub s}>1), referred to as short wavelength ion temperature gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k{sub y}{rho}{sub s}<1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression.

Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar (India); Brunner, S.; Lapillonne, X.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Jenko, F. [Max-Planck-Institut fuer Plasmaphysik Boltzmannstr. 2, D-85748 Garching (Germany)

2012-10-15T23:59:59.000Z

71

PREDICTION OF THE PROTON-TO-TOTAL TURBULENT HEATING IN THE SOLAR WIND  

SciTech Connect

This paper employs a recent turbulent heating prescription to predict the ratio of proton-to-total heating due to the kinetic dissipation of Alfvenic turbulence as a function of heliocentric distance. Comparing to a recent empirical estimate for this turbulent heating ratio in the high-speed solar wind, the prediction shows good agreement with the empirical estimate for R {approx}> 0.8 AU, but predicts less ion heating than the empirical estimate at smaller heliocentric radii. At these smaller radii, the turbulent heating prescription, calculated in the gyrokinetic limit, fails because the turbulent cascade is predicted to reach the proton cyclotron frequency before Landau damping terminates the cascade. These findings suggest that the turbulent cascade can reach the proton cyclotron frequency at R {approx}< 0.8 AU, leading to a higher level of proton heating than predicted by the turbulent heating prescription in the gyrokinetic limit. At larger heliocentric radii, R {approx}> 0.8 AU, this turbulent heating prescription contains all of the necessary physical mechanisms needed to reproduce the empirically estimated proton-to-total heating ratio.

Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)

2011-09-01T23:59:59.000Z

72

Effects of turbulence on power generation for variable-speed wind turbines  

DOE Green Energy (OSTI)

One of the primary advantages of variable-speed wind turbines over fixed-speed turbines should be improved aerodynamic efficiency. With variable-speed generation, in order to maintain a constant ratio of wind speed to tip speed, the wind turbine changes rotor speed as the wind speed changes. In this paper we compare a stall-controlled, variable-speed wind turbine to a fixed-speed turbine. The focus of this paper is to investigate the effects of variable speed on energy capture and its ability to control peak power. We also show the impact of turbulence on energy capture in moderate winds. In this report, we use a dynamic simulator to apply different winds to a wind turbine model. This model incorporates typical inertial and aerodynamic performance characteristics. From this study we found a control strategy that makes it possible to operate a stall-controlled turbine using variable speed to optimize energy capture and to control peak power. We also found that turbulence does not have a significant impact on energy capture.

Muljadi, E.; Butterfield, C.P.; Buhl, M.L. Jr.

1996-11-01T23:59:59.000Z

73

Turbulence Anisotropy Determined by Wind Profiler Radar and Its Correlation with Rain Events in Montreal, Canada  

Science Conference Proceedings (OSTI)

Turbulence inhomogeneities at 3-m scales can be either isotropic or anisotropic, and the degree of anisotropy can be measured with VHF wind profiler radars. Studies over a period of two years in Montreal, Quebec, Canada, have shown that for this ...

Anna Hocking; Wayne K. Hocking

2007-01-01T23:59:59.000Z

74

Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loading: Preprint  

DOE Green Energy (OSTI)

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5 MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.

Lee, S.; Churchfield, M.; Moriarty, P.; Jonkman, J.; Michalakes, J.

2011-12-01T23:59:59.000Z

75

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

76

Near-Surface Turbulence and Thermal Structure in a Wind-Driven Sea  

Science Conference Proceedings (OSTI)

Ocean surface turbulence at high sea states is evaluated using heat as a naturally occurring passive tracer. A freely drifting instrument with a mechanically driven temperature profiler, fixed depth thermistors, and conductivity cells was used to ...

Johannes R. Gemmrich; David M. Farmer

1999-03-01T23:59:59.000Z

77

Oceanic Quasi-geostrophic Turbulence Forced by Stochastic Wind Fluctuations  

Science Conference Proceedings (OSTI)

The quasi-geostrophic response to stochastic wind fluctuations is calculated using a doubly periodic nonlinear model, with a vertical resolution of three modes in most cases. The influence of various parameters on the response is investigated: ...

Anne Marie Treguier; Bach Lien Hua

1987-03-01T23:59:59.000Z

78

Turbulent Heating in the Solar Wind and in the Solar Corona  

E-Print Network (OSTI)

In this paper we calculate the turbulent heating rates in the solar wind using the Kolmogorov-like MHD turbulence phenomenology with Kolmogorov's constants calculated by {\\it Verma and Bhattacharjee }[1995b,c]. We find that the turbulent heating can not account for the total heating of the nonAlfv\\'enic streams in the solar wind. We show that dissipation due to thermal conduction is also a potential heating source. Regarding the Alfv\\'enic streams, the predicted turbulent heating rates using the constants of {\\it Verma and Bhattacharjee }[1995c] are higher than the observed heating rates; the predicted dissipation rates are probably overestimates because Alfv\\'enic streams have not reached steady-state. We also compare the predicted turbulent heating rates in the solar corona with the observations; the Kolmogorov-like phenomenology predicts dissipation rates comparable to the observed heating rates in the corona [{\\it Hollweg, }% 1984], but Dobrowoly et al.'s generalized Kraichnan model yields heating rates much less than that required.

Mahendra K. Verma

1995-09-05T23:59:59.000Z

79

Turbulent Heating in the Solar Wind and in the Solar Corona  

E-Print Network (OSTI)

In this paper we calculate the turbulent heating rates in the solar wind using the Kolmogorov-like MHD turbulence phenomenology with Kolmogorov’s constants calculated by Verma and Bhattacharjee [1995b,c]. We find that the turbulent heating can not account for the total heating of the nonAlfvénic streams in the solar wind. We show that dissipation due to thermal conduction is also a potential heating source. Regarding the Alfvénic streams, the predicted turbulent heating rates using the constants of Verma and Bhattacharjee [1995c] are higher than the observed heating rates; the predicted dissipation rates are probably overestimates because Alfvénic streams have not reached steady-state. We also compare the predicted turbulent heating rates in the solar corona with the observations; the Kolmogorov-like phenomenology predicts dissipation rates comparable to the observed heating rates in the corona [Hollweg, 1984], but Dobrowoly et al.’s generalized Kraichnan model yields heating rates much less than that required. 1 1

Mahendra K. Verma

2008-01-01T23:59:59.000Z

80

Wind and Turbulence in a Sparse but Regular Plant Canopy  

Science Conference Proceedings (OSTI)

Wind velocity statistics from several points within a regular but sparse array of clumped corn plants are analyzed, with each clump consisting of 12 plants, having a mean height of 1.6 m and a collective leaf area of about 2.75 m2 and occupying ...

Andree Tuzet; John D. Wilson

2002-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

82

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

83

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

84

Quality Controls for Profiler Measurements of Winds and RASS Temperatures  

Science Conference Proceedings (OSTI)

A new method for estimating winds and radio acoustic sounding system temperatures from radar Doppler measurements for the new NOAA wind profilers is described. This method emphasizes the quality of 6-min measurements prior to the computation of ...

B. L. Weber; D. B. Wuertz; D. C. Welsh; R. McPeek

1993-08-01T23:59:59.000Z

85

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

86

INVESTIGATION OF INTERMITTENCY IN MAGNETOHYDRODYNAMICS AND SOLAR WIND TURBULENCE: SCALE-DEPENDENT KURTOSIS  

SciTech Connect

The behavior of scale-dependent (or filtered) kurtosis is studied in the solar wind using magnetic field measurements from the ACE and Cluster spacecraft at 1 AU. It is also analyzed numerically with high-resolution magnetohydrodynamic spectral simulations. In each case the filtered kurtosis increases with wavenumber, implying the presence of coherent structures at the smallest scales. This phase coupling is related to intermittency in solar wind turbulence and the emergence of non-Gaussian statistics. However, it is inhibited by the presence of upstream waves and other phase-randomizing structures, which act to reduce the growth of kurtosis.

Wan Minping; Osman, Kareem T.; Matthaeus, William H. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Oughton, Sean, E-mail: mpwan@bartol.udel.edu [Department of Mathematics, University of Waikato, Hamilton 3240 (New Zealand)

2012-01-10T23:59:59.000Z

87

Wind reversals in turbulent Rayleigh-Benard convection  

E-Print Network (OSTI)

The phenomenon of irregular cessation and subsequent reversal of the large-scale circulation in turbulent Rayleigh-B\\'enard convection is theoretically analysed. The force and thermal balance on a single plume detached from the thermal boundary layer yields a set of coupled nonlinear equations, whose dynamics is related to the Lorenz equations. For Prandtl and Rayleigh numbers in the range $10^{-2} \\leq \\Pr \\leq 10^{3}$ and $10^{7} \\leq \\Ra \\leq 10^{12}$, the model has the following features: (i) chaotic reversals may be exhibited at Ra $\\geq 10^{7}$; (ii) the Reynolds number based on the root mean square velocity scales as $\\Re_{rms} \\sim \\Ra^{[0.41 ... 0.47]}$ (depending on Pr), and as $\\Re_{rms} \\sim \\Pr^{-[0.66 ... 0.76]}$ (depending on Ra); and (iii) the mean reversal frequency follows an effective scaling law $\\omega / (\

Francisco Fontenele Araujo; S. Grossmann; D. Lohse

2004-07-13T23:59:59.000Z

88

FRAME DEPENDENCE OF THE ELECTRIC FIELD SPECTRUM OF SOLAR WIND TURBULENCE  

Science Conference Proceedings (OSTI)

We present the first survey of electric field data using the ARTEMIS spacecraft in the solar wind to study inertial range turbulence. It was found that the average perpendicular spectral index of the electric field depends on the frame of measurement. In the spacecraft frame it is -5/3, which matches the magnetic field due to the large solar wind speed in Lorentz transformation. In the mean solar wind frame, the electric field is primarily due to the perpendicular velocity fluctuations and has a spectral index slightly shallower than -3/2, which is close to the scaling of the velocity. These results are an independent confirmation of the difference in scaling between the velocity and magnetic field, which is not currently well understood. The spectral index of the compressive fluctuations was also measured and found to be close to -5/3, suggesting that they are not only passive to the velocity but may also interact nonlinearly with the magnetic field.

Chen, C. H. K.; Bale, S. D.; Salem, C.; Mozer, F. S., E-mail: chen@ssl.berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2011-08-20T23:59:59.000Z

89

Numerical Study of the Effects of Atmospheric and Wake Turbulence on Wind Turbine Dynamics  

SciTech Connect

Although the atmospheric sciences community has been studying the effects of atmospheric stability and surface roughness on the planetary boundary layer for some time, their effects on wind turbine dynamics have not been well studied. In this study, we performed numerical experiments to explore some of the effects of atmospheric stability and surface roughness on wind turbine dynamics. We used large-eddy simulation to create atmospheric winds and compute the wind turbine flows, and we modeled the wind turbines as revolving and flexible actuator lines coupled to a wind turbine structural and system dynamic model. We examined the structural moments about the wind turbine blade, low-speed shaft, and nacelle; power production; and wake evolution when large 5-MW turbines are subjected to winds generated from low- and high-surface roughness levels representative of offshore and onshore conditions, respectively, and also neutral and unstable atmospheric conditions. In addition, we placed a second turbine 7 rotor diameters downwind of the first one so that we could explore wake effects under these different conditions. The results show that the turbulent structures generated within the atmospheric boundary layer wind simulations cause isolated loading events at least as significant as when a turbine is waked by an upwind turbine. The root-mean-square (RMS) turbine loads are consistently larger when the surface roughness is higher. The RMS blade-root out-of-plane bending moment and low-speed shaft torque are higher when the atmospheric boundary layer is unstable as compared with when it is neutral. However, the RMS yaw moments are either equal or reduced in the unstable case as compared with the neutral case. For a given surface roughness, the ratio of power produced by the downwind turbine relative to that of the upwind turbine is 15-20% higher when the conditions are unstable as compared with neutral. For a given atmospheric stability, this power ratio is 10% higher with the onshore roughness value versus the offshore one. The main conclusion is that various coherent turbulent structures that form under different levels of atmospheric stability and surface roughness have important effects on wind turbine structural response, power production, and wake evolution.

Churchfield, M. J.; Lee, S.; Michalakes, J.; Moriarty, P. J.

2012-01-01T23:59:59.000Z

90

Temperature, Humidity, and Wind at the Global Tropopause  

Science Conference Proceedings (OSTI)

This study presents global statistics of tropopause parameters for a 15-yr period (1979–93). The parameters are height, temperature, potential temperature, mixing ratio of water vapor, and zonal, meridional and vertical wind. The global ...

Klaus P. Hoinka

1999-10-01T23:59:59.000Z

91

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

92

Chaotic mean wind in turbulent thermal convection and long-term correlations in solar activity  

E-Print Network (OSTI)

It is shown that correlation function of the mean wind velocity in a turbulent thermal convection (Rayleigh number $Ra \\sim 10^{11}$) exhibits exponential decay with a very long correlation time, while corresponding largest Lyapunov exponent is certainly positive. These results together with the reconstructed phase portrait indicate presence of a chaotic component in the examined mean wind. Telegraph approximation is also used to study relative contribution of the chaotic and stochastic components to the mean wind fluctuations and an equilibrium between these components has been studied. Since solar activity is based on the thermal convection processes, it is reasoned that the observed solar activity long-term correlations can be an imprint of the mean wind chaotic properties. In particular, correlation function of the daily sunspots number exhibits exponential decay with a very long correlation time and corresponding largest Lyapunov exponent is certainly positive, also relative contribution of the chaotic and stochastic components follows the same pattern as for the convection mean wind.

A. Bershadskii

2009-08-27T23:59:59.000Z

93

Full vector (3-D) inflow simulation in natural and wind farm environments using an expanded version of the SNLWIND (Veers) turbulence code  

DOE Green Energy (OSTI)

We have recently expanded the numerical turbulence simulation (SNLWIND) developed by Veers [1] to include all three components of the turbulent wind vector. We have also configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm, as well as over uniform, flat terrain. Veers`s original method only simulates the longitudinal component of the wind in neutral flow. This paper overviews the development of spectral distribution, spatial coherence, and cross correlation models used to expired the SNLWIND code to include the three components of the turbulent wind over a range of atmospheric stabilities. These models are based on extensive measurements of the turbulence characteristics immediately upwind and downwind of a large wind farm in San Gorgonio Pass, California.

Kelley, N.D.

1992-11-01T23:59:59.000Z

94

Full vector (3-D) inflow simulation in natural and wind farm environments using an expanded version of the SNLWIND (Veers) turbulence code  

DOE Green Energy (OSTI)

We have recently expanded the numerical turbulence simulation (SNLWIND) developed by Veers [1] to include all three components of the turbulent wind vector. We have also configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm, as well as over uniform, flat terrain. Veers's original method only simulates the longitudinal component of the wind in neutral flow. This paper overviews the development of spectral distribution, spatial coherence, and cross correlation models used to expired the SNLWIND code to include the three components of the turbulent wind over a range of atmospheric stabilities. These models are based on extensive measurements of the turbulence characteristics immediately upwind and downwind of a large wind farm in San Gorgonio Pass, California.

Kelley, N.D.

1992-11-01T23:59:59.000Z

95

Flow visualization using momentum and energy transport tubes and applications to turbulent flow in wind farms  

E-Print Network (OSTI)

As a generalization of the mass-flux based classical stream-tube, the concept of momentum and energy transport tubes is discussed as a flow visualization tool. These transport tubes have the property, respectively, that no fluxes of momentum or energy exist over their respective tube mantles. As an example application using data from large-eddy simulation, such tubes are visualized for the mean-flow structure of turbulent flow in large wind farms, in fully developed wind-turbine-array boundary layers. The three-dimensional organization of energy transport tubes changes considerably when turbine spacings are varied, enabling the visualization of the path taken by the kinetic energy flux that is ultimately available at any given turbine within the array.

Meyers, Johan

2012-01-01T23:59:59.000Z

96

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

97

Numerical simulation to determine the effects of incident wind shear and turbulence level on the flow around a building  

Science Conference Proceedings (OSTI)

The effects of incident shear and turbulence on flow around a cubical building are being investigated by a turbulent kinetic energy/dissipation model (TEMPEST). The numerical simulations demonstrate significant effects due to the differences in the incident flow. The addition of upstream turbulence and shear results in a reduced size of the cavity directly behind the building. The accuracy of numerical simulations is verified by comparing the predicted mean flow fields with the available wind-tunnel measurements of Castro and Robins (1977). Comparing the authors' results with experimental data, the authors show that the TEMPEST model can reasonably simulate the mean flow.

Zhang, Y.Q.; Huber, A.H.; Arya, S.P.S.; Snyder, W.H.

1992-01-01T23:59:59.000Z

98

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

99

Measurement in a wind tunnel of the modification of mean wind and turbulence characteristics due to induction effects near wind turbine rotors  

DOE Green Energy (OSTI)

It is the purpose of this report to provide experimental data on the wind field surrounding a single model wind turbine rotor disk. These data should provide an improved physical insight into the induction effects of the air flow as it approaches the wind turbine. This insight should in turn improve an analytical model's predictive capabilities. A scaled model of a horizontal-axis wind turbine (a two-bladed rotor of diameter 53 cm) was placed into the Meteorological Wind Tunnel (MWT) facility at Colorado State University (cross-section width of 183 cm). Four different approach flow conditions were studied: low and moderate turbulence levels (0.1% and 1.5% intensity) at both 6 and 7.6 m/s freestream air velocities. For each of these flow conditions the rotor power coefficient versus tip speed ratio was obtained, and the 3-dimensional velocity field from 3 rotor diameters upwind to 0.5 diameter downwind was tabulated. The power output of the rotor was obtained via a simple prony brake friction device that imparts a torque (measured by the deflection of a spring) to the spinning shaft of the wind turbine. The rotor speed, measured by a strobe light, was observed to vary with load from 900 rpm up to 2100 rpm for the flow conditions described above. The 3-dimensional velocity field was measured via a three-hot-film probe. Details of the measurement techniques are provided. The test program and data results are also given. A short discussion of the implications of this data set is included. 12 refs., 19 figs., 11 tabs.

Neff, D.E.; Meroney, R.N.

1987-08-01T23:59:59.000Z

100

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

102

Calculation of Surface Fluxes under Convective Conditions by Turbulence Closure Models  

Science Conference Proceedings (OSTI)

A method of deriving new relationships between near-surface turbulent fluxes and vertical differences of wind speed and potential temperature between two levels in the atmospheric surface layer from simplified second-order turbulence closure ...

Lech ?obocki

2001-03-01T23:59:59.000Z

103

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

104

DISTRIBUTION OF MAGNETIC DISCONTINUITIES IN THE SOLAR WIND AND IN MAGNETOHYDRODYNAMIC TURBULENCE  

Science Conference Proceedings (OSTI)

The statistical properties of magnetic discontinuities in the solar wind are investigated by measuring fluctuations in the magnetic field direction, given by the rotation {Delta}{theta} that the magnetic field vector undergoes during time interval {Delta}t. We show that the probability density function, P({Delta}{theta}), can be described by a simple model in which the magnetic field vector purely rotates with a relative increment {Delta}B/B that is lognormally distributed. We find that the probability density function of increments, P({Delta}B/B), has a remarkable scaling property: the normalized variable x = ({Delta}B/B) {center_dot} ({Delta}t/{Delta}t{sub 0}){sup -{alpha}} has a universal lognormal distribution for all time intervals {Delta}t. We then compare measurements from the solar wind with those from direct numerical simulations of magnetohydrodynamic (MHD) turbulence. We find good agreement for P({Delta}{theta}) obtained in the two cases when the magnetic guide field to fluctuations ratio B{sub 0}/b{sub rms} is chosen accordingly. However, the scale invariance of P({Delta}B/B) is broken in the MHD simulations with relatively limited inertial interval, which causes P({Delta}{theta}) to scale with measurement interval differently than in the solar wind.

Zhdankin, Vladimir; Boldyrev, Stanislav [Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706 (United States); Mason, Joanne [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)

2012-12-01T23:59:59.000Z

105

Distribution of Magnetic Discontinuities in the Solar Wind and in MHD Turbulence  

E-Print Network (OSTI)

The statistical properties of magnetic discontinuities in the solar wind are investigated by measuring fluctuations in the magnetic field direction, given by the rotation Delta theta that the magnetic field vector undergoes during time interval Delta t. We show that the probability density function for rotations, P(Delta theta), can be described by a simple model in which the magnetic field vector rotates with a relative increment (Delta B)/B that is lognormally distributed. We find that the probability density function of increments, P((Delta B)/B), has a remarkable scaling property: the normalized variable x=[(Delta B)/B]*[(Delta t)/(Delta t_0)]^-a has a universal lognormal distribution for all time intervals Delta t. We then compare measurements from the solar wind with those from direct numerical simulations of magnetohydrodynamic (MHD) turbulence. We find good agreement for P(Delta theta) obtained in the two cases when the magnetic guide-field to fluctuations ratio B_0/b_rms is chosen accordingly. However, the scale invariance of P((Delta B)/B) is broken in the MHD simulations with relatively limited inertial interval, which causes P(Delta theta) to scale with measurement interval differently than in the solar wind.

Vladimir Zhdankin; Stanislav Boldyrev; Joanne Mason

2012-10-12T23:59:59.000Z

106

Estimation of Surface Turbulent Fluxes through Assimilation of Radiometric Surface Temperature Sequences  

Science Conference Proceedings (OSTI)

A model of land surface energy balance is used as a constraint on the estimation of factors characterizing land surface influences on evaporation and turbulent heat transfer from sequences of radiometric surface temperature measurements. The ...

Francesca Caparrini; Fabio Castelli; Dara Entekhabi

2004-02-01T23:59:59.000Z

107

Radiative Effects on Turbulent Temperature Spectra and Budgets in the Planetary Boundary Layer  

Science Conference Proceedings (OSTI)

The effects of radiative energy transfer on turbulent temperature fields are studied, and preliminary estimates show the infrared “radiative dissipation” mechanism to be dominant. Spectral computations for the idealized homogeneous-isotropic case ...

M. Coantic; O. Simonin

1984-09-01T23:59:59.000Z

108

Wind Shear Enhancement of Entrainment and Refractive Index Structure Parameter at the Top of a Turbulent Mixed Layer  

Science Conference Proceedings (OSTI)

A model for inversion layer turbulence properties of a cloud-free entraining mixed-layer with wind shear at the top is developed. Using the approach of Wyngaard and LeMone (1980), expressions for the average values of ? and ?w2 in the entrainment ...

C. W. Fairall

1984-12-01T23:59:59.000Z

109

Power law burst and inter-burst interval distributions in the solar wind: turbulence or dissipative SOC ?  

E-Print Network (OSTI)

We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval tau for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P(e) and P(T) to be power laws, consistent with self-organised criticality (SOC). We find also a power law form for P(tau) that distinguishes this turbulent cascade from the exponential P(tau) of ideal SOC, but not from some other SOC-like sandpile models. We discuss the implications for the relation between SOC and turbulence.

M. P. Freeman; N. W. Watkins; D. J. Riley

2000-03-08T23:59:59.000Z

110

Wake Turbulence of Two NREL 5-MW Wind Turbines Immersed in a Neutral Atmospheric Boundary-Layer Flow  

E-Print Network (OSTI)

The fluid dynamics video considers an array of two NREL 5-MW turbines separated by seven rotor diameters in a neutral atmospheric boundary layer (ABL). The neutral atmospheric boundary-layer flow data were obtained from a precursor ABL simulation using a Large-Eddy Simulation (LES) framework within OpenFOAM. The mean wind speed at hub height is 8m/s, and the surface roughness is 0.2m. The actuator line method (ALM) is used to model the wind turbine blades by means of body forces added to the momentum equation. The fluid dynamics video shows the root and tip vortices emanating from the blades from various viewpoints. The vortices become unstable and break down into large-scale turbulent structures. As the wakes of the wind turbines advect further downstream, smaller-scale turbulence is generated. It is apparent that vortices generated by the blades of the downstream wind turbine break down faster due to increased turbulence levels generated by the wake of the upstream wind turbine.

Bashioum, Jessica L; Schmitz, Sven; Duque, Earl P N

2013-01-01T23:59:59.000Z

111

Example of Reduced Turbulence during Thunderstorm Outflow  

Science Conference Proceedings (OSTI)

The vertical structures of turbulence, winds, and temperatures are analyzed from a 92-m instrumented tower and a collocated acoustic sodar during an outflow episode from a weak thunderstorm over sloping terrain in northern New Mexico. Prior to ...

Brent M. Bowen

1996-06-01T23:59:59.000Z

112

ON THE LOW-FREQUENCY BOUNDARY OF SUN-GENERATED MAGNETOHYDRODYNAMIC TURBULENCE IN THE SLOW SOLAR WIND  

Science Conference Proceedings (OSTI)

New aspects of the slow solar wind turbulent heating and acceleration are investigated. A physical meaning of the lower boundary of the Alfven wave turbulent spectra in the solar atmosphere and the solar wind is studied and the significance of this natural parameter is demonstrated. Via an analytical and quantitative treatment of the problem we show that a truncation of the wave spectra from the lower frequency side, which is a consequence of the solar magnetic field structure and its cyclic changes, results in a significant reduction of the heat production and acceleration rates. An appropriate analysis is presented regarding the link of the considered problem with existing observational data and slow solar wind initiation scenarios.

Shergelashvili, Bidzina M.; Fichtner, Horst [Institut fuer Theoretische Physik IV, Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

2012-06-20T23:59:59.000Z

113

A Numerical Model Study of Nocturnal Drainage Flows with Strong Wind and Temperature Gradients  

Science Conference Proceedings (OSTI)

A second-moment turbulence-closure model described in Yamada and Bunker is used to simulate nocturnal drainage flows observed during the 1984 ASCOT field expedition in Brush Creek, Colorado. In order to simulate the observed strong wind ...

T. Yamada; S. Bunker

1989-07-01T23:59:59.000Z

114

Solar turbulence in earth's global and regional temperature anomalies Nicola Scafetta,1,2  

E-Print Network (OSTI)

Solar turbulence in earth's global and regional temperature anomalies Nicola Scafetta,1,2 Paolo a study of the influence of solar activity on the earth's temperature. In particular, we focus on the repercussion of the fluctuations of the solar irradiance on the temperature of the Northern and Southern

Scafetta, Nicola

115

Temperature, Humidity, Wind and Pressure Sensors (THWAPS) Handbook  

SciTech Connect

The temperature, humidity, wind, and pressure system (THWAPS) provide surface reference values of these measurements for balloon-borne sounding system (SONDE) launches. The THWAPS is located adjacent to the SONDE launch site at the Southern Great Plains (SGP) Central Facility. The THWAPS system is a combination of calibration-quality instruments intended to provide accurate measurements of meteorological conditions near the surface. Although the primary use of the system is to provide accurate surface reference values of temperature, pressure, relative humidity (RH), and wind velocity for comparison with radiosonde readings, the system includes a data logger to record time series of the measured variables.

Ritsche, MT

2011-01-17T23:59:59.000Z

116

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

117

DIRECT NUMERICAL SIMULATION OF RADIATION PRESSURE-DRIVEN TURBULENCE AND WINDS IN STAR CLUSTERS AND GALACTIC DISKS  

SciTech Connect

The pressure exerted by the radiation of young stars may be an important feedback mechanism that drives turbulence and winds in forming star clusters and the disks of starburst galaxies. However, there is great uncertainty in how efficiently radiation couples to matter in these high optical depth environments. In particular, it is unclear what levels of turbulence the radiation can produce, and whether the infrared radiation trapped by the dust opacity can give rise to heavily mass-loaded winds. In this paper, we report a series of two-dimensional flux-limited diffusion radiation-hydrodynamics calculations performed with the code ORION in which we drive strong radiation fluxes through columns of dusty matter confined by gravity in order to answer these questions. We consider both systems where the radiation flux is sub-Eddington throughout the gas column, and those where it is super-Eddington at the midplane but sub-Eddington in the atmosphere. In the latter, we find that the radiation-matter interaction gives rise to radiation-driven Rayleigh-Taylor instability, which drives supersonic turbulence at a level sufficient to fully explain the turbulence seen in Galactic protocluster gas clouds, and to make a non-trivial contribution to the turbulence observed in starburst galaxy disks. However, the instability also produces a channel structure in which the radiation-matter interaction is reduced compared to time-steady analytic models because the radiation field is not fully trapped. For astrophysical parameters relevant to forming star clusters and starburst galaxies, we find that this effect reduces the net momentum deposition rate in the dusty gas by a factor of {approx}2-6 compared to simple analytic estimates, and that in steady state the Eddington ratio reaches unity and there are no strong winds. We provide an approximation formula, appropriate for implementation in analytic models and non-radiative simulations, for the force exerted by the infrared radiation field in this regime.

Krumholz, Mark R. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Thompson, Todd A., E-mail: krumholz@ucolick.org, E-mail: thompson@astronomy.ohio-state.edu [Department of Astronomy and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210-1173 (United States)

2012-12-01T23:59:59.000Z

118

Low-Order Modelling of Blade-Induced Turbulence for RANS Actuator Disk Computations of Wind and Tidal Turbines  

E-Print Network (OSTI)

Modelling of turbine blade-induced turbulence (BIT) is discussed within the framework of three-dimensional Reynolds-averaged Navier-Stokes (RANS) actuator disk computations. We first propose a generic (baseline) BIT model, which is applied only to the actuator disk surface, does not include any model coefficients (other than those used in the original RANS turbulence model) and is expected to be valid in the limiting case where BIT is fully isotropic and in energy equilibrium. The baseline model is then combined with correction functions applied to the region behind the disk to account for the effect of rotor tip vortices causing a mismatch of Reynolds shear stress between short- and long-time averaged flow fields. Results are compared with wake measurements of a two-bladed wind turbine model of Medici and Alfredsson [Wind Energy, Vol. 9, 2006, pp. 219-236] to demonstrate the capability of the new model.

Nishino, Takafumi

2012-01-01T23:59:59.000Z

119

Covariability of Surface Wind and Stress Responses to Sea Surface Temperature Fronts  

Science Conference Proceedings (OSTI)

The responses of surface wind and wind stress to spatial variations of sea surface temperature (SST) are investigated using satellite observations of the surface wind from the Quick Scatterometer (QuikSCAT) and SST from the Advanced Microwave ...

Larry W. O’Neill; Dudley B. Chelton; Steven K. Esbensen

2012-09-01T23:59:59.000Z

120

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

A comparison of predicted and observed turbulent wind fields present in natural and internal wind park environments  

DOE Green Energy (OSTI)

This paper assesses the accuracy of simulated wind fields for both the natural flow and that within a wind park environment. The simulated fields are compared with the observed ones in both the time and frequency domains. Actual measurements of the wind fields and the derived kinematic scaling parameters upwind and downwind of a large San Gorgonio Pass wind park are used. The deviations in the modeled wind field from the observed are discussed. 10 refs., 6 figs., 2 tabs.

Kelly, N D; Wright, A D

1991-10-01T23:59:59.000Z

122

Role of ion temperature on scrape-off layer plasma turbulence  

SciTech Connect

Turbulence in Scrape-off layer (SOL) of tokamak plasma has been studied numerically using interchange modes with the help of electron continuity, quasineutrality, and ion energy equations. Electron temperature is assumed uniform. We have studied dynamics of seeded plasma blob and plasma turbulence to identify the role of ion temperature and its gradient. The ion temperature elongates the blob poloidally and reduces its radial velocity. Initial dipole nature of the plasma blob potential breaks and generates few more dipoles during its propagation in the SOL. Plasma turbulence simulation shows poloidally elongated density and ion temperature structures that are similar to the seeded blob simulation studies. Fluctuations of the density and ion temperature have been presented as function of scale lengths of the density and ion temperature. Reduction of the SOL width and increase of radial electric field have been measured in the presence of the ion temperature. Particle and energy transports have been also presented as the function of the density and ion temperature scale lengths.

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

2013-04-15T23:59:59.000Z

123

Errors of Five-Day Mean Surface Wind and Temperature Conditions due to Inadequate Sampling  

Science Conference Proceedings (OSTI)

Surface meteorological reports of wind components, wind speed, air temperature, and sea surface temperature from buoys located in equatorial and midlatitude regions are used in a simulation of random sampling to determine errors of the calculated ...

David M. Legler

1991-10-01T23:59:59.000Z

124

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

125

Origin of the Temperature Oscillation in Turbulent Thermal Convection  

E-Print Network (OSTI)

We report an experimental study of the three-dimensional spatial structure of the low frequency temperature oscillations in a cylindrical Rayleigh-B\\'{e}nard convection cell. It is found that thermal plumes are not emitted periodically, but randomly and continuously, from the top and bottom plates. We further found that the oscillation of the temperature field does not originate from the boundary layers, but rather is a result of the horizontal motion of the hot ascending and cold descending fluids being modulated by the twisting and sloshing motion of the bulk flow field.

Xi, Heng-Dong; Zhou, Quan; Chan, Tak-Shing; Xia, Ke-Qing

2008-01-01T23:59:59.000Z

126

Solar-wind turbulence and shear: a superposed-epoch analysis of corotating interaction regions at 1 AU  

Science Conference Proceedings (OSTI)

A superposed-epoch analysis of ACE and OMNI2 measurements is performed on 27 corotating interaction regions (CIRs) in 2003-2008, with the zero epoch taken to be the stream interface as determined by the maximum of the plasma vorticity. The structure of CIRs is investigated. When the flow measurements are rotated into the local-Parker-spiral coordinate system the shear is seen to be abrupt and intense, with vorticities on the order of 10{sup -5}-10{sup -4} sec{sup -1}. Converging flows perpendicular to the stream interface are seen in the local-Parker-spiral coordinate system and about half of the CIRs show a layer of divergent rebound flow away from the stream interface. Arguments indicate that any spreading of turbulence away from the region where it is produced is limited to about 10{sup 6} km, which is very small compared with the thickness of a CrR. Analysis of the turbulence across the CrRs is performed. When possible, the effects of discontinuities are removed from the data. Fluctuation amplitudes, the Alfvenicity, and the level of Alfvenic correlations all vary smoothly across the CrR. The Alfven ratio exhibits a decrease at the shear zone of the stream interface. Fourier analysis of 4.5-hr subintervals of ACE data is performed and the results are superposed averaged as an ensemble of realizations. The spectral slopes of the velocity, magnetic-field, and total-energy fluctuations vary smoothly across the CIR. The total-energy spectral slope is {approx} 3/2 in the slow and fast wind and in the CrRs. Analysis of the Elsasser inward-outward fluctuations shows a smooth transition across the CrR from an inward-outward balance in the slow wind to an outward dominance in the fast wind. A number of signatures of turbulence driving at the shear zone are sought (entropy change, turbulence amplitude, Alfvenicity, Alfven ratio, spectral slopes, in-out nature): none show evidence of driving of turbulence by shear.

Borovsky, Joseph E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV.

2009-01-01T23:59:59.000Z

127

Measurement of Clear-Air Gradients and Turbulence Properties with Radar Wind Profilers  

Science Conference Proceedings (OSTI)

An experiment comparing balloon and profiler observations was carried out to evaluate the capability of Doppler radar wind profilers to remotely measure useful meteorological quantities other than wind. The site chosen was in Southern California ...

E. E. Gossard; D. E. Wolfe; K. P. Moran; R. A. Paulus; K. D. Anderson; L. T. Rogers

1998-04-01T23:59:59.000Z

128

Diurnal Evolution of Three-Dimensional Wind and Temperature Structure in California's Central Valley  

Science Conference Proceedings (OSTI)

The diurnal evolution of the three-dimensional summer-season mean wind and temperature structure in California's Sacramento and San Joaquin Valleys (collectively called the Central Valley) is investigated using data from 22 radar wind profiler/...

Shiyuan Zhong; C. David Whiteman; Xindi Bian

2004-11-01T23:59:59.000Z

129

Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer  

Science Conference Proceedings (OSTI)

In the middle of the convective atmospheric boundary layer is often a deep layer of vertically uniform wind speed (MUL), wind direction, and potential temperature (?UL). A radix layer is identified as the whole region below this uniform layer, ...

Edi Santoso; Roland Stull

1998-06-01T23:59:59.000Z

130

Petascale Simulations of Inhomogeneous Alfvén 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

131

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

132

Lagrangian Coherent Structure Analysis of Terminal Winds Detected by Lidar. Part I: Turbulence Structures  

Science Conference Proceedings (OSTI)

The accurate real-time detection of turbulent airflow patterns near airports is important for safety and comfort in commercial aviation. In this paper, a method is developed to identify Lagrangian coherent structures (LCS) from horizontal lidar ...

Wenbo Tang; Pak Wai Chan; George Haller

2011-02-01T23:59:59.000Z

133

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

134

Turbulent Transfer Coefficients and Calculation of Air Temperature inside Tall Grass Canopies in Land–Atmosphere Schemes for Environmental Modeling  

Science Conference Proceedings (OSTI)

A method for estimating profiles of turbulent transfer coefficients inside a vegetation canopy and their use in calculating the air temperature inside tall grass canopies in land surface schemes for environmental modeling is presented. The ...

D. T. Mihailovic; K. Alapaty; B. Lalic; I. Arsenic; B. Rajkovic; S. Malinovic

2004-10-01T23:59:59.000Z

135

Wind Stress and Heat Flux over the Ocean in Gale Force Winds  

Science Conference Proceedings (OSTI)

An offshore stable platform has been instrumented with wind turbulence, temperature and wave height sensors. Data from this platform have been analyzed by the eddy correlation method to obtain wind stress and heat flux at wind speeds from 6 to 22 ...

Stuart D. Smith

1980-05-01T23:59:59.000Z

136

A New Analysis to Diagnose Ageostrophic Winds from Wind and Temperature Measurements Made by an Observational Network  

Science Conference Proceedings (OSTI)

The present paper is devoted to a new analysis of winds and temperature measurements made by an observational network in order to provide the 3D ageostrophic circulations. This analysis may be used with data from instrumented networks providing ...

Y. Lemaître; P. Neveux; G. Scialom

1994-06-01T23:59:59.000Z

137

The Minimum Wind Speed for Sustainable Turbulence in the Nocturnal Boundary Layer  

Science Conference Proceedings (OSTI)

The collapse of turbulence in the nocturnal boundary layer is studied by means of a simple bulk model that describes the basic physical interactions in the surface energy balance. It is shown that for a given mechanical forcing, the amount of ...

B. J. H. Van de Wiel; A. F. Moene; H. J. J. Jonker; P. Baas; S. Basu; J. M. M. Donda; J. Sun; A. A. M. Holtslag

2012-11-01T23:59:59.000Z

138

Wind Direction Dependence of Atmospheric Boundary Layer Turbulence Parameters in the Urban Roughness Sublayer  

Science Conference Proceedings (OSTI)

A variety of atmospheric boundary layer parameters are examined as a function of wind direction in both urban and suburban settings in Oklahoma City, Oklahoma, derived from measurements during the Joint Urban 2003 field campaign. Heterogeneous ...

Cheryl Klipp

2007-12-01T23:59:59.000Z

139

Turbulence Spectra and Dissipation Rates in a Wind Tunnel Model of the Atmospheric Convective Boundary Layer  

Science Conference Proceedings (OSTI)

A model of the atmospheric convective boundary layer (CBL) is realized in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources, University of Karlsruhe. Further experimental results from this model are presented. ...

Rolf Kaiser; Evgeni Fedorovich

1998-02-01T23:59:59.000Z

140

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

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


141

A Climatology of Atmospheric Wavenumber Spectra of Wind and Temperature Observed by Commercial Aircraft  

Science Conference Proceedings (OSTI)

Atmospheric wavenumber spectra of wind and temperature have been obtained from over 6000 commercial aircraft flights made during the Global Atmospheric Sampling Program. Temperature and velocity spectra are approximately the same shape over the ...

G. D. Nastrom; K. S. Gage

1985-05-01T23:59:59.000Z

142

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

143

Analysis of CASES-99 Lidar and Turbulence Data in Support of Wind Turbine Effects: April 1, 2001 to Januay 31, 2003  

DOE Green Energy (OSTI)

The nocturnal low-level jet (LLJ) of the Great Plains of the central United States has been identified as a promising source of high-momentum wind flow for wind energy. The acceleration of the winds after sunset above the surface produces a jet profile in the wind velocity, with maximum speeds that often exceed 10 m s-1 or more at heights near 100 m or more. These high wind speeds are advantageous for wind energy generation. The high speeds aloft, however, also produce a region of high shear between the LLJ and the earth's surface, where the nocturnal flow is often calm or nearly so. This shear zone below the LLJ generates atmospheric waves and turbulence that can cause strong vibration in the turbine rotors. It has been suggested that these vibrations contribute to premature failures in large wind turbines, which, of course, would be a considerable disadvantage for wind energy applications. In October 1999, a field project called the Cooperative Atmosphere-Surface Exchange Study 1999 campaign, or CASES-99, was conducted in southeastern Kansas to study the nocturnal stable boundary layer. One of the instruments deployed during CASES-99 was the High-Resolution Doppler Lidar, a new scanning, remote-sensing, wind-mapping instrument.

Banta, R. M.

2003-06-01T23:59:59.000Z

144

The momentum flux probability distribution function for ion-temperature-gradient turbulence  

SciTech Connect

There has been overwhelming evidence that coherent structures play a critical role in determining the overall transport in a variety of systems. We compute the probability distribution function (PDF) tails of momentum flux and heat flux in ion-temperature-gradient turbulence, by taking into account the interaction among modons, which are assumed to be coherent structures responsible for bursty and intermittent events, contributing to the PDF tails. The tail of PDF of momentum flux R= is shown to be exponential with the form exp(-{xi}R{sup 3/2}), which is broader than a Gaussian, similar to what was found in the previous local studies. An analogous expression with the same functional dependence is found for the PDF tails of heat flux. Furthermore, we present a detailed numerical study of the dependence of the PDF tail on the temperature and density scale lengths and other physical parameters through the coefficient {xi}.

Anderson, Johan; Kim, Eun-jin [University of Sheffield, Department of Applied Mathematics, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2008-05-15T23:59:59.000Z

145

A Bulk Turbulent Air–Sea Flux Algorithm for High-Wind, Spray Conditions  

Science Conference Proceedings (OSTI)

Sensible and latent heat can cross the air–sea interface by two routes: as interfacial fluxes controlled by molecular processes right at the interface, and as spray fluxes from the surface of sea spray droplets. Once the 10-m wind speed over the ...

Edgar L. Andreas; P. Ola G. Persson; Jeffrey E. Hare

2008-07-01T23:59:59.000Z

146

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

147

TURBULENT HEAT TRANSPORT IN TWO-AND THREE-DIMENSIONAL TEMPERATURE FIELDS  

E-Print Network (OSTI)

Most fluid flows and heat transfer processes of practicalfor turbulent heat and mass transfer processes. The study

Samaraweera, D.S.A.

2011-01-01T23:59:59.000Z

148

1404 JOURNAL OF CLIMATE VOLUME 16 Covariations of Sea Surface Temperature and Wind over the Kuroshio and Its Extension: Evidence for Ocean-to-Atmosphere Feedback*  

E-Print Network (OSTI)

Satellite microwave measurements are analyzed, revealing robust covariability in sea surface temperature (SST) and wind speed over the Kuroshio Extension (KE) east of Japan. Ocean hydrodynamic instabilities cause the KE to meander and result in large SST variations. Increased (reduced) wind speeds are found to be associated with warm (cold) SST anomalies. This positive SST–wind correlation in KE is confirmed by in situ buoy measurements and is consistent with a vertical shear adjustment mechanism. Namely, an increase in SST reduces the static stability of the near-surface atmosphere, intensifying the vertical turbulence mixing and bringing fastmoving air from aloft to the sea surface. South of Japan, the Kuroshio is known to vary between nearshore and offshore paths. These paths are very persistent and can last for months to years. As the Kuroshio shifts its path, coherent wind changes are detected from satellite data. In particular, winds are high south of Tokyo when the Kuroshio takes the nearshore path while they are greatly reduced when this warm current leaves the coast in the offshore path. The positive SST–wind correlation over the strong Kuroshio Current and its extension is opposite to the negative one often observed in regions of weak currents such as south of the Aleutian low. The latter correlation is considered to be indicative of atmosphere-to-ocean forcing. 1.

Masami Nonaka; Shang-ping Xie

2002-01-01T23:59:59.000Z

149

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

SciTech Connect

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

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

2006-12-01T23:59:59.000Z

150

Wind and Temperature Structure over a Land-Water-Land Area  

Science Conference Proceedings (OSTI)

Wind and temperature data obtained on 5 June 1984 during the Øresund experiment are analyzed. The day was characterized by moderately strong winds blowing from a heated land area over a colder water surface and then over a second heated land ...

J. C. Doran; Sven-Erik Gryning

1987-08-01T23:59:59.000Z

151

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

152

Dynamic Stability of a Three-Layer Model with Discontinuous Profiles of Wind and Temperature  

Science Conference Proceedings (OSTI)

A theoretical three-layer model for tropospheric gravity waves with discontinuous vertical profiles of both wind and temperature is examined. The asymmetry of the model increases the difficulty in solving the equations but allows a more accurate ...

Sebastián Monserrat; Clemente Ramis

1990-09-01T23:59:59.000Z

153

Retrieval of Microscale Wind and Temperature Fields from Single- and Dual-Doppler Lidar Data  

Science Conference Proceedings (OSTI)

Dual-Doppler lidar observations are used to assess the accuracy of single-Doppler retrievals of microscale wind and temperature fields in a shear-driven convective boundary layer. The retrieval algorithm, which is based on four-dimensional ...

Rob K. Newsom; David Ligon; Ron Calhoun; Rob Heap; Edward Cregan; Marko Princevac

2005-09-01T23:59:59.000Z

154

Extraction of Geopotential Height and Temperature Structure from Profiler and Rawinsonde Winds  

Science Conference Proceedings (OSTI)

Mesoscale height and temperature fields can be extracted from the observed wind field by making use of the full divergence equation. Mass changes associated with irrotational ageostrophic motions are retained for a nearly complete description of ...

Steven Businger; Michael E. Adams; Steven E. Koch; Michael L. Kaplan

2001-07-01T23:59:59.000Z

155

Vertical Mixing and the Temperature and Wind Structure of the Tropical Tropopause Layer  

Science Conference Proceedings (OSTI)

We show that vertical mixing can lead to significant momentum and heat fluxes in the tropical tropopause layer (TTL) and that these momentum and heat fluxes can force large climatological temperature and zonal wind changes in the TTL. We present ...

Thomas J. Flannaghan; Stephan Fueglistaler

156

Retrieving Temperature and Geopotential Fields from a Network of Wind Profiler Observations  

Science Conference Proceedings (OSTI)

In this paper, we extend the 1985 work of Kuo and Anthes to develop a method to derive temperature and geopotential information from a network of wind profiler observations, which we define as a thermodynamic retrieval technique. We first ...

Ying-Hwa Kuo; David O. Gill; Linsheng Cheng

1987-12-01T23:59:59.000Z

157

Sea Surface Temperature and Wind Stress Curl Variability near a Cape  

Science Conference Proceedings (OSTI)

The coupling between sea surface temperature (SST), SST gradients, and wind stress curl variability near a cape off Brazil is investigated using satellite observations and several different SST high-resolution analyses. The cape is characterized ...

Renato M. Castelao

2012-11-01T23:59:59.000Z

158

Theoretical Interpretation of Atmospheric Wavenumber Spectra of Wind and Temperature Observed by Commercial Aircraft During GASP  

Science Conference Proceedings (OSTI)

This paper contains a theoretical interpretation of the wavenumber spectra of wind and temperature obtained from an analysis of data from over 6900 flights during the Global Atmospheric Sampling Program. The spectra cover scales ranging from 3 km ...

K. S. Gage; G. D. Nastrom

1986-04-01T23:59:59.000Z

159

Effects of Soil Moisture on Temperatures, Winds, and Pollutant Concentrations in Los Angeles  

Science Conference Proceedings (OSTI)

This paper examines the effects of soil moisture initialization in a coupled air quality–meteorological model on temperature profiles, wind speeds, and pollutant concentrations. Three simulations, each with different initial soil moisture fields, ...

Mark Z. Jacobson

1999-05-01T23:59:59.000Z

160

Recovery of Three-Dimensional Wind and Temperature Fields from Simulated Single-Doppler Radar Data  

Science Conference Proceedings (OSTI)

A method for recovering the full three-dimensional wind and temperature fields from single-Doppler radar data is developed and demonstrated. This method uses a dynamic model, and attempts to determine the initial conditions of the unobserved flow ...

Juanzhen Sun; Dawn W. Flicker; Douglas K. Lilly

1991-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Coupling between Sea Surface Temperature and Low-Level Winds in Mesoscale Numerical Models  

Science Conference Proceedings (OSTI)

This study evaluates the impacts of sea surface temperature (SST) specification and grid resolution on numerical simulations of air–sea coupling near oceanic fronts through analyses of surface winds from the European Centre for Medium-Range ...

Qingtao Song; Dudley B. Chelton; Steven K. Esbensen; Nicolai Thum; Larry W. O’Neill

2009-01-01T23:59:59.000Z

162

Evaluations of Mesoscale Models' Simulations of Near-Surface Winds, Temperature Gradients, and Mixing Depths  

Science Conference Proceedings (OSTI)

Mesoscale meteorological models are being used to provide inputs of winds, vertical temperature and stability structure, mixing depths, and other parameters to atmospheric transport and dispersion models. An evaluation methodology is suggested ...

Steven R. Hanna; Ruixin Yang

2001-06-01T23:59:59.000Z

163

Summertime Coupling between Sea Surface Temperature and Wind Stress in the California Current System  

Science Conference Proceedings (OSTI)

Satellite observations of wind stress and sea surface temperature (SST) are analyzed to investigate ocean–atmosphere interaction in the California Current System (CCS). As in regions of strong SST fronts elsewhere in the World Ocean, SST in the ...

Dudley B. Chelton; Michael G. Schlax; Roger M. Samelson

2007-03-01T23:59:59.000Z

164

Wind and Temperature Retrievals in the 17 May 1981 Arcadia, Oklahoma, Supercell: Ensemble Kalman Filter Experiments  

Science Conference Proceedings (OSTI)

The feasibility of using an ensemble Kalman filter (EnKF) to retrieve the wind and temperature fields in an isolated convective storm has been tested by applying the technique to observations of the 17 May 1981 Arcadia, Oklahoma, tornadic ...

David C. Dowell; Fuqing Zhang; Louis J. Wicker; Chris Snyder; N. Andrew Crook

2004-08-01T23:59:59.000Z

165

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

166

Fallacies of the Enthalpy Transfer Coefficient over the Ocean in High Winds  

Science Conference Proceedings (OSTI)

Mesoscale and large-scale atmospheric models use a bulk surface flux algorithm to compute the turbulent flux boundary conditions at the bottom of the atmosphere from modeled mean meteorological quantities such as wind speed, temperature, and ...

Edgar L Andreas

2011-07-01T23:59:59.000Z

167

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

168

High-Resolution In Situ Profiling through the Stable Boundary Layer: Examination of the SBL Top in Terms of Minimum Shear, Maximum Stratification, and Turbulence Decrease  

Science Conference Proceedings (OSTI)

Some 50 separate high-resolution profiles of small-scale turbulence defined by the energy dissipation rate (?), horizontal wind speed, and temperature from near the surface, through the nighttime stable boundary layer (SBL), and well into the ...

B. B. Balsley; R. G. Frehlich; M. L. Jensen; Y. Meillier

2006-04-01T23:59:59.000Z

169

Variations of Winds and Turbulence Seen by the 50-MHz Radar at White Sands Missile Range, New Mexico  

Science Conference Proceedings (OSTI)

The mean vertical profiles of the winds from about 5 to 20 km at White Sands Missile Range, New Mexico, are described. The variability of wind speed, spectral width, volume reflectivity calibrated as CN2, and vertical wind shear are documented as ...

G. D. Nastrom; F. D. Eaton

1995-10-01T23:59:59.000Z

170

Stochastic Heating, Differential Flow, and the Alpha-to-Proton Temperature Ratio in the Solar Wind  

E-Print Network (OSTI)

We extend previous theories of stochastic ion heating to account for the motion of ions along the magnetic field. We derive an analytic expression for the ion-to-proton perpendicular temperature ratio in the solar wind for any ion species, assuming that stochastic heating is the dominant ion heating mechanism. This expression describes how this temperature ratio depends upon the average velocity of the ions along the magnetic field direction and the ratio of the parallel proton pressure to the magnetic pressure. We compare our model with previously published measurements of alpha particles and protons from the WIND spacecraft. We find that stochastic heating offers a promising explanation for these measurements when the fractional cross helicity and Alfven ratio at the proton-gyroradius scale have values that are broadly consistent with solar-wind measurements.

Chandran, B D G; Quataert, E; Kasper, J C; Isenberg, P A; Bourouaine, S

2013-01-01T23:59:59.000Z

171

Statistical Analysis of Sodium Doppler Wind–Temperature Lidar Measurements of Vertical Heat Flux  

Science Conference Proceedings (OSTI)

A statistical study is presented of the errors in sodium Doppler lidar measurements of wind and temperature in the mesosphere that arise from the statistics of the photon-counting process that is inherent in the technique. The authors use data ...

Liguo Su; Richard L. Collins; David A. Krueger; Chiao-Yao She

2008-03-01T23:59:59.000Z

172

Inverse Parameter Estimation of the Turbulent Surface Layer from Single-Level Data and Surface Temperature  

Science Conference Proceedings (OSTI)

A simple inverse parameter estimation method is used in a practical diagnostic approach to obtain the surface roughness lengths and surface resistance parameters from a chi-square cost function containing measurements of wind speed and air ...

P. Martano

2008-04-01T23:59:59.000Z

173

Electron-Ion Temperature Equilibration in Collisionless Shocks: the Supernova Remnant-Solar Wind Connection  

E-Print Network (OSTI)

Collisionless shocks are loosely defined as shocks where the transition between pre-and post-shock states happens on a length scale much shorter than the collisional mean free path. In the absence of collision to enforce thermal equilibrium post-shock, electrons and ions need not have the same temperatures. While the acceleration of electrons for injection into shock acceleration processes to produce cosmic rays has received considerable attention, the related problem of the shock heating of quasi-thermal electrons has been relatively neglected. In this paper we review that state of our knowledge of electron heating in astrophysical shocks, mainly associated with supernova remnants (SNRs), shocks in the solar wind associated with the terrestrial and Saturnian bowshocks, and galaxy cluster shocks. The solar wind and SNR samples indicate that the ratio of electron temperature to ion temperature declines with increasing shock speed or Alfvenic Mach number. We discuss the extent to which such behavior can be unde...

Ghavamian, Parviz; Mitchell, Jeremy; Masters, Adam; Laming, J Martin

2013-01-01T23:59:59.000Z

174

Magnetic Fluctuation Power Near Proton Temperature Anisotropy Instability Thresholds in the Solar Wind  

Science Conference Proceedings (OSTI)

The proton temperature anisotropy in the solar wind is known to be constrained by the theoretical thresholds for pressure-anisotropy-driven instabilities. Here, we use approximately 1x10{sup 6} independent measurements of gyroscale magnetic fluctuations in the solar wind to show for the first time that these fluctuations are enhanced along the temperature anisotropy thresholds of the mirror, proton oblique firehose, and ion cyclotron instabilities. In addition, the measured magnetic compressibility is enhanced at high plasma beta (beta{sub ||} > or approx. 1) along the mirror instability threshold but small elsewhere, consistent with expectations of the mirror mode. We also show that the short wavelength magnetic fluctuation power is a strong function of collisionality, which relaxes the temperature anisotropy away from the instability conditions and reduces correspondingly the fluctuation power.

Bale, S. D. [Physics Department and Space Sciences Laboratory, University of California, Berkeley, California (United States); Kasper, J. C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts (United States); Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa (United States); Quataert, E. [Physics Department and Astronomy Department, University of California, Berkeley, California (United States); Salem, C.; Sundkvist, D. [Space Sciences Laboratory, University of California, Berkeley, California (United States)

2009-11-20T23:59:59.000Z

175

Fluctuating wind power penetration as limited by frequency standard.  

E-Print Network (OSTI)

??Fluctuating wind power is due to wind turbulence and is the part which should be filtered out leaving behind the more predictable mean wind power… (more)

Luo, Changling, 1980-

2005-01-01T23:59:59.000Z

176

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

177

Winding Transitions at Finite Energy and Temperature: An O(3) Model  

E-Print Network (OSTI)

Winding number transitions in the two dimensional softly broken O(3) nonlinear sigma model are studied at finite energy and temperature. New periodic instanton solutions which dominate the semiclassical transition amplitudes are found analytically at low energies, and numerically for all energies up to the sphaleron scale. The Euclidean period beta of these finite energy instantons increases with energy, contrary to the behavior found in the abelian Higgs model or simple one dimensional systems. This results in a sharp crossover from instanton dominated tunneling to sphaleron dominated thermal activation at a certain critical temperature. Since this behavior is traceable to the soft breaking of conformal invariance by the mass term in the sigma model, semiclassical winding number transition amplitudes in the electroweak theory in 3+1 dimensions should exhibit a similar sharp crossover. We argue that this is indeed the case in the standard model for M_H < 4 M_W.

Salman Habib; Emil Mottola; Peter Tinyakov

1996-08-14T23:59:59.000Z

178

Similarity Equations for Wind and Temperature Profiles in the Radix Layer, at the Bottom of the Convective Boundary Layer  

Science Conference Proceedings (OSTI)

In the middle of the convective boundary layer, also known as the mixed layer, is a relatively thick region where wind speed and potential temperature are nearly uniform with height. Below this uniform layer (UL), wind speed decreases to zero at ...

Edi Santoso; Roland Stull

2001-06-01T23:59:59.000Z

179

Utility of Radiosonde Wind Data in Representing Climatological Variations of Tropospheric Temperature and Baroclinicity in the Western Tropical Pacific  

Science Conference Proceedings (OSTI)

The utility of the thermal wind equation (TWE) in relating tropospheric (850–300 hPa) wind and temperature on climatological time scales is assessed, based on data from 59 radiosonde stations in the western tropical Pacific during 1979–2004. ...

Robert J. Allen; Steven C. Sherwood

2007-11-01T23:59:59.000Z

180

Energy and Buildings, 8 (1985) 105 -122 105 Temperature-and Wind-induced Air Flow Patterns  

E-Print Network (OSTI)

Energy and Buildings, 8 (1985) 105 - 122 105 Temperature- and Wind-induced Air Flow Patterns measurements, wind pressure data and air infiltration calculation. INTRODUCTION Studies on the energy,B. DICKINSON,D. GRIMSRUDand R. LIPSCHUTZ Energy Performance of Buildings Group, Energy and Environment Division

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Comparative Assessment of Direct Drive High Temperature Superconducting Generators in Multi-Megawatt Class Wind Turbines  

DOE Green Energy (OSTI)

This paper summarizes the work completed under the CRADA between NREL and American Superconductor (AMSC). The CRADA combined NREL and AMSC resources to benchmark high temperature superconducting direct drive (HTSDD) generator technology by integrating the technologies into a conceptual wind turbine design, and comparing the design to geared drive and permanent magnet direct drive (PMDD) wind turbine configurations. Analysis was accomplished by upgrading the NREL Wind Turbine Design Cost and Scaling Model to represent geared and PMDD turbines at machine ratings up to 10 MW and then comparing cost and mass figures of AMSC's HTSDD wind turbine designs to theoretical geared and PMDD turbine designs at 3.1, 6, and 10 MW sizes. Based on the cost and performance data supplied by AMSC, HTSDD technology has good potential to compete successfully as an alternative technology to PMDD and geared technology turbines in the multi megawatt classes. In addition, data suggests the economics of HTSDD turbines improve with increasing size, although several uncertainties remain for all machines in the 6 to 10 MW class.

Maples, B.; Hand, M.; Musial, W.

2010-10-01T23:59:59.000Z

182

Comparative Assessment of Direct Drive High Temperature Superconducting Generators in Multi-Megawatt Class Wind Turbines  

SciTech Connect

This paper summarizes the work completed under the CRADA between NREL and American Superconductor (AMSC). The CRADA combined NREL and AMSC resources to benchmark high temperature superconducting direct drive (HTSDD) generator technology by integrating the technologies into a conceptual wind turbine design, and comparing the design to geared drive and permanent magnet direct drive (PMDD) wind turbine configurations. Analysis was accomplished by upgrading the NREL Wind Turbine Design Cost and Scaling Model to represent geared and PMDD turbines at machine ratings up to 10 MW and then comparing cost and mass figures of AMSC's HTSDD wind turbine designs to theoretical geared and PMDD turbine designs at 3.1, 6, and 10 MW sizes. Based on the cost and performance data supplied by AMSC, HTSDD technology has good potential to compete successfully as an alternative technology to PMDD and geared technology turbines in the multi megawatt classes. In addition, data suggests the economics of HTSDD turbines improve with increasing size, although several uncertainties remain for all machines in the 6 to 10 MW class.

Maples, B.; Hand, M.; Musial, W.

2010-10-01T23:59:59.000Z

183

Wake Characteristics of the MOD-2 Wind Turbine at Medicine Bow, Wyoming  

SciTech Connect

The present paper summarizes results obtained from profile measurements of the MOD-2 wind turbine wake at Medicine Bow, Wyoming. Vertical profiles of wind speed, potential temperature, and turbulence at 3 and 7 rotor diameters downstream of the turbine, taken under near neutral or slightly stable atmospheric conditions, are presented.

Jacobs, E. W.; Kelley, N. D.; McKenna, H. E.; Birkenheuer, N. B.

1984-11-01T23:59:59.000Z

184

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

185

MARIAH-A Similarity-Based Method for Determining Wind, Temperature, and Humidity Profile Structure in the Atmospheric Surface Layer  

Science Conference Proceedings (OSTI)

Methodology for determining the similarity scaling constants for wind, temperature, and specific humidity from micrometeorological tower data is presented. The equations and the approach for solving them are referred to as MARIAH. The MARIAH ...

Henry Rachele; Arnold Tunick; Frank V. Hansen

1995-04-01T23:59:59.000Z

186

The Impact of Radar Data on Short-Term Forecasts of Surface Temperature, Dewpoint Depression, and Wind Speed  

Science Conference Proceedings (OSTI)

A statistical system that uses surface observations and radar data to provide 1-, 3-, and 6-h forecasts of temperature, dewpoint depression, and wind speed is developed. Application of the system to independent data demonstrates that the radar ...

Emily K. Grover-Kopec; J. Michael Fritsch

2003-12-01T23:59:59.000Z

187

Dynamical Response of the Oceanic Circulation and Temperature to Interdecadal Variability in the Surface Winds over the Indian Ocean  

Science Conference Proceedings (OSTI)

A global ocean general circulation model (OGCM) is used to investigate the sensitivity of the circulation and temperature fields to observed interdecadal variability in Indian Ocean winds for the austral summer (January, February, March). Focus ...

C. J. C. Reason; R. J. Allan; J. A. Lindesay

1996-01-01T23:59:59.000Z

188

Relative Roles of Elevated Heating and Surface Temperature Gradients in Driving Anomalous Surface Winds over Tropical Oceans  

Science Conference Proceedings (OSTI)

Elevated heating by cumulus convection and sea surface temperature gradients are both thought to contribute to surface winds over tropical oceans. The relative strength and role of each mechanism is examined by imposing forcing derived from data ...

John C. H. Chiang; Stephen E. Zebiak; Mark A. Cane

2001-06-01T23:59:59.000Z

189

A Theory for the Retrievals of Virtual Temperature from Remote Measurements of Horizontal Winds and Thermal Radiation  

Science Conference Proceedings (OSTI)

This paper develops a theory for the estimation of virtual temperature from remote measurements of (i) emitted thermal radiation by microwave and infrared radiometers and (ii) horizontal winds by Doppler radars (or lidars). The problem of ...

Tzvi Gal-Chen

1988-06-01T23:59:59.000Z

190

The Determination of Surface-Layer Stability and Eddy Fluxes Using Wind Speed and Vertical Temperature Gradient Measurements  

Science Conference Proceedings (OSTI)

Analytical relations are developed that relate the Monin-Obukhov parameter to a modified bulk Richardson number expressed in terms of measured wind speed and vertical temperature difference. Measured Monin-Obukhov parameters and Richardson ...

I. T. Wang

1981-10-01T23:59:59.000Z

191

Examination of Errors in Near-Surface Temperature and Wind from WRF Numerical Simulations in Regions of Complex Terrain  

Science Conference Proceedings (OSTI)

The performance of an advanced research version of the Weather Research and Forecasting Model (WRF) in predicting near-surface atmospheric temperature and wind conditions under various terrain and weather regimes is examined. Verification of 2-m ...

Hailing Zhang; Zhaoxia Pu; Xuebo Zhang

2013-06-01T23:59:59.000Z

192

Assimilation of High-Resolution Mode-S Wind and Temperature Observations in a Regional NWP Model for Nowcasting Applications  

Science Conference Proceedings (OSTI)

In this paper the beneficial impacts of high-resolution (in space and time) wind and temperature observations from aircraft on very short-range numerical weather forecasting are presented. The observations are retrieved using the tracking and ...

Siebren de Haan; Ad Stoffelen

2012-08-01T23:59:59.000Z

193

On the Loss of Wind-Induced Near-Inertial Energy to Turbulent Mixing in the Upper Ocean  

Science Conference Proceedings (OSTI)

Wind-induced near-inertial energy has been believed to be an important source for generating the ocean mixing required to maintain the global meridional overturning circulation. In the present study, the near-inertial energy budget in a realistic ...

Xiaoming Zhai; Richard J. Greatbatch; Carsten Eden; Toshiyuki Hibiya

2009-11-01T23:59:59.000Z

194

High-Temperature Motor Windings for Downhole Pumps Used in Geothermal Energy Production  

Science Conference Proceedings (OSTI)

The development of highly reliable downhole equipment is an essential element in enabling the widespread utilization of Enhanced Geothermal Systems (EGS). The downhole equipment used in these systems will be required to operate at high voltages and temperatures on the order of 200 to 250°C (and eventually to 300?C). These conditions exceed the practical operating ranges of currently available thermoplastic wire insulations, and thus limit the operating lifetime of tools such as Electric Submersible Pumps (ESPs). In this work, high-temperature insulations based on composite materials were developed and demonstrated. The products of this work were found to exhibit electrical resistivities and dielectric breakdown strengths that PEEK at temperatures above 250C. In addition, sub-scale motor windings were fabricated and tested to validate the performance of this technology

Hooker, Matthew; Hazelton, Craig; Kano, Kimi

2010-12-31T23:59:59.000Z

195

System and method for monitoring and controlling stator winding temperature in a de-energized AC motor  

Science Conference Proceedings (OSTI)

A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Lu, Bin (Kenosha, WI); Luebke, Charles John (Sussex, WI); Habetler, Thomas G. (Snellville, GA); Zhang, Pinjia (Atlanta, GA); Becker, Scott K. (Oak Creek, WI)

2011-12-27T23:59:59.000Z

196

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

197

ASYMMETRIC SOLAR WIND ELECTRON DISTRIBUTIONS  

Science Conference Proceedings (OSTI)

The present paper provides a possible explanation for the solar wind electron velocity distribution functions possessing asymmetric energetic tails. By numerically solving the electrostatic weak turbulence equations that involve nonlinear interactions among electrons, Langmuir waves, and ion-sound waves, it is shown that different ratios of ion-to-electron temperatures lead to the generation of varying degrees of asymmetric tails. The present finding may be applicable to observations in the solar wind near 1 AU and in other regions of the heliosphere and interplanetary space.

Yoon, Peter H.; Kim, Sunjung; Lee, Junggi; Lee, Junhyun; Park, Jongsun; Park, Kyungsun; Seough, Jungjoon [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Hong, Jinhy [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)

2012-08-20T23:59:59.000Z

198

Retrieving Horizontal Temperature Gradients and Advections from Single-Station Wind Profiler Observations  

Science Conference Proceedings (OSTI)

Vertical wind shears measured by the Plattevilie, Colorado wind profiler were used in conjunction with the geostrophic thermal wind equation to retrieve the horizontal thermal gradients and associated advections for a case involving an upper-...

Paul J. Neiman; M. A. Shapiro

1989-06-01T23:59:59.000Z

199

Diagnostic Analysis of Tidal Winds and the Eliassen–Palm Flux Divergence in the Mesosphere and Lower Thermosphere from TIMED/SABER Temperatures  

Science Conference Proceedings (OSTI)

For migrating tides or fast-moving planetary waves, polarization relations derived from the linear wave equations are required to accurately derive the wind components from the temperature field. A common problem in diagnosing winds from the ...

Xun Zhu; Jeng-Hwa Yee; E. R. Talaat; M. Mlynczak; J. M. Russell III

2008-12-01T23:59:59.000Z

200

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Modeling of Trade Wind Cumuli with a Low-Order Turbulence Model: Toward a Unified Description of Cu and Se Clouds in Meteorological Models  

Science Conference Proceedings (OSTI)

A simple method is proposed to extend a low-order turbulence scheme including a subgrid-scale cloudiness scheme to represent not only nonconvective (stratiform) cloudiness and turbulence but also shallow, nonprecipitating cumulus convection by ...

P. Bechtold; J. W. M. Cuijpers; P. Mascart; P. Trouilhet

1995-02-01T23:59:59.000Z

202

Homogeneous Quasi-Geostrophic Turbulence Driven by a Uniform Temperature Gradient  

Science Conference Proceedings (OSTI)

Statistically steady states consistent with a horizontally uniform time-averaged temperature gradient in a two-layer quasi-geostrophic model on a beta-plane are found by numerically integrating the equations for deviations from this mean state in ...

Dale B. Haidvogel; Isaac M. Held

1980-12-01T23:59:59.000Z

203

Turbine Inflow Characterization at the National Wind Technology Center  

Science Conference Proceedings (OSTI)

Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results show that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

Clifton, A.; Schreck, S.; Scott, G.; Kelley, N.; Lundquist, J. K.

2012-01-01T23:59:59.000Z

204

Turbine Inflow Characterization at the National Wind Technology Center: Preprint  

DOE Green Energy (OSTI)

Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results shown that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

Clifton, A.; Schreck, S.; Scott, G.; Kelley, N.; Lundquist, J.

2012-01-01T23:59:59.000Z

205

Controlling hour-long power of wind farms.  

E-Print Network (OSTI)

??In attempting to control the power output of a wind farm, it is first necessary to smooth the power fluctuations due to wind turbulence. This… (more)

Li, Pei, 1981-

2007-01-01T23:59:59.000Z

206

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

207

Frequency-Wavenumber Spectra of Sea Surface Temperature and Wind-Stress Curl in the Eastern North Pacific  

Science Conference Proceedings (OSTI)

Frequency-wavenumber spectra of sea surface temperature and wind-stress curl are computed from 11 years of surface marine observations taken in the eastern North Pacific. These data were averaged by month and 2° quadrangles to yield spectra with ...

Artemio Gallegos-Garcia; William J. Emery; Robert O. Reid; Lorenz Magaard

1981-08-01T23:59:59.000Z

208

Free and Forced Variability of the Tropical Atlantic Ocean: Role of the Wind–Evaporation–Sea Surface Temperature Feedback  

Science Conference Proceedings (OSTI)

The role of the wind–evaporation–sea surface temperature (WES) feedback in the low-frequency natural variability of the tropical Atlantic is studied using an atmospheric global climate model—the NCAR Community Climate Model, version 3 (CCM3)—...

Salil Mahajan; R. Saravanan; Ping Chang

2010-11-01T23:59:59.000Z

209

The Impact of Spume Droplets and Wave Stress Parameterizations on Simulated Near-Surface Maritime Wind and Temperature  

Science Conference Proceedings (OSTI)

The influence of ocean gravity waves on the wind and temperature above the surface is investigated using a one-dimensional boundary layer model. The effect of the wave-induced stress is evaluated using three parameterizations: wave age (WaAg), ...

Valdir Innocentini; Iury Angelo Gonçalves

2010-06-01T23:59:59.000Z

210

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

211

Turbulence Kinetic Energy Budget Profiles Derived from Doppler Sodar Measurements  

Science Conference Proceedings (OSTI)

Doppler sodar wind measurements made in light wind conditions in September 1979 near a power plant in Turbigo, Italy, are used to derive terms in the turbulence kinetic energy (TKE) budget. Measurements on five days are grouped into two classes: ...

Gary K. Greenhut; Giangiuseppe Mastrantonio

1989-02-01T23:59:59.000Z

212

Investigation of Flow, Turbulence, and Dispersion within Built Environments  

E-Print Network (OSTI)

Properties of the wind field within the Oklahoma City ParkProperties of the wind field within the Oklahoma City Parkwinds, turbulence, and dispersion in built-up downtown areas of Oklahoma

Pan, Hansheng

2011-01-01T23:59:59.000Z

213

Characterizing Inflow Conditions Across the Rotor Disk of a Utility-Scale Wind Turbine (Poster)  

DOE Green Energy (OSTI)

Multi-megawatt utility-scale wind turbines operate in a turbulent, thermally-driven atmosphere where wind speed and air temperature vary with height. Turbines convert the wind's momentum into electrical power, and so changes in the atmosphere across the rotor disk influence the power produced by the turbine. To characterize the inflow into utility scale turbines at the National Wind Technology Center (NWTC) near Boulder, Colorado, NREL recently built two 135-meter inflow monitoring towers. This poster introduces the towers and the measurements that are made, showing some of the data obtained in the first few months of operation in 2011.

Clifton, A.; Lundquist, J. K.; Kelley, N.; Scott, G.; Jager, D.; Schreck, S.

2012-01-01T23:59:59.000Z

214

Wind Mixing and Restratification in a Lake near the Temperature of Maximum Density  

Science Conference Proceedings (OSTI)

The cooling of a freshwater take provides an opportunity for studying wind mixing and restratification under the peculiar conditions associated with a density maximum. The concepts are explored using a mixing-layer model that incorporates both ...

David M. Farmer; Eddy Carmack

1981-11-01T23:59:59.000Z

215

Effects of Small-Scale Vertical Motion on Radar Measurements of Wind and Temperature Profiles  

Science Conference Proceedings (OSTI)

Vertical velocities were observed during the month of June 1990 with two side-by-side wind profilers at Platteville, Colorado. Many of the observations reveal strong wave motion, probably mountain lee waves, that sometimes caused vertical ...

B. L. Weber; D. B. Wuertz; D. C. Law; A. S. Frisch; J. M. Brown

1992-06-01T23:59:59.000Z

216

Wind characteristics for agricultural wind energy applications  

SciTech Connect

Wind energy utilization in agriculture can provide a potentially significant savings in fuel oil consumption and ultimately a cost savings to the farmer. A knowledge of the wind characteristics within a region and at a location can contribute greatly to a more efficient and cost-effective use of this resource. Current research indicates that the important wind characteristics include mean annual wind speed and the frequency distribution of the wind, seasonal and diurnal variations in wind speed and direction, and the turbulent and gustiness characteristics of the wind. Further research is underway to provide a better definition of the total wind resource available, improved methods for siting WECS and an improved understanding of the environment to which the WECS respond.

Renne, D. S.

1979-01-01T23:59:59.000Z

217

Intermittent Dissipation and Local Heating in the Solar Wind  

E-Print Network (OSTI)

Evidence for inhomogeneous heating in the interplanetary plasma near current sheets dynamically generated by magnetohydrodynamic (MHD) turbulence is obtained using measurements from the ACE spacecraft. These coherent structures only constitute 19% of the data, but contribute 50% of the total plasma internal energy. Intermittent heating manifests as elevations in proton temperature near current sheets, resulting in regional heating and temperature enhancements extending over several hours. The number density of non-Gaussian structures is found to be proportional to the mean proton temperature and solar wind speed. These results suggest magnetofluid turbulence drives intermittent dissipation through a hierarchy of coherent structures, which collectively could be a significant source of coronal and solar wind heating.

Osman, K T; Wan, M; Rappazzo, A F

2011-01-01T23:59:59.000Z

218

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

219

Mesoscale Influences of Wind Farms throughout a Diurnal Cycle  

Science Conference Proceedings (OSTI)

Large wind farms are expected to influence local and regional atmospheric circulations. Using a mesoscale parameterization of the effects of wind farms that includes a momentum sink and a wind speed–dependent source of turbulent kinetic energy, ...

Anna C. Fitch; Julie K. Lundquist; Joseph B. Olson

2013-07-01T23:59:59.000Z

220

The Turbulence Structure of Nocturnal Slope Flow  

Science Conference Proceedings (OSTI)

Measurements of the turbulence structure of nocturnal slope flow are used to test the hypothesis that slope flow turbulence in the region above the low-level wind maximum is decoupled from the surface and has a local structure similar to that ...

T. W. Horst; J. C. Doran

1988-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Crop Wind Energy Experiment (CWEX): Observations of Surface-Layer, Boundary Layer, and Mesoscale Interactions with a Wind Farm  

Science Conference Proceedings (OSTI)

Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, ...

Daniel A. Rajewski; Eugene S. Takle; Julie K. Lundquist; Steven Oncley; John H. Prueger; Thomas W. Horst; Michael E. Rhodes; Richard Pfeiffer; Jerry L. Hatfield; Kristopher K. Spoth; Russell K. Doorenbos

2013-05-01T23:59:59.000Z

222

The Vertical Profile of Wind and Temperature in Cyclones and Anticyclones over the Eastern Two-Thirds of the United States: A Climatology  

Science Conference Proceedings (OSTI)

A climatological analysis, based upon operational surface and upper-air data from 1957 to 1994, of the wind and temperature profiles composited with respect to each quadrant of surface cyclones and anticyclones, is presented for the eastern two-...

Howard B. Bluestein; Peter C. Banacos

2002-03-01T23:59:59.000Z

223

A Comparative Assessment of Surface Wind Speed and Sea Surface Temperature over the Indian Ocean by TMI, MSMR, and ERA-40  

Science Conference Proceedings (OSTI)

A 2-yr (June 1999–June 2001) observation of ocean surface wind speed (SWS) and sea surface temperature (SST) derived from microwave radiometer measurements made by a multifrequency scanning microwave radiometer (MSMR) and the Tropical Rainfall ...

Anant Parekh; Rashmi Sharma; Abhijit Sarkar

2007-06-01T23:59:59.000Z

224

An Analysis of Near-Surface Winds, Air Temperature, and Cyclone Activity in Terra Nova Bay, Antarctica, from 1993 to 2009  

Science Conference Proceedings (OSTI)

In September 2009, the first unmanned aerial vehicles were flown over Terra Nova Bay, Antarctica, to collect information regarding air–sea interactions. Prior to the field season, wind and temperature data from a local automatic weather station (...

Shelley L. Knuth; John J. Cassano

2011-03-01T23:59:59.000Z

225

WIND DATA REPORT Gardner NCCI  

E-Print Network (OSTI)

/RERL_Fact_Sheet_6_Wind_resource_interpretation.pdf * 1 m/s = 2.237 mph. SECTION 1 January 30, 2008 Renewable Energy, and wind roses are included in APPENDIX B. January 30, 2008 Renewable Energy Research Laboratory Page 8 ­ Turbulent Intensity vs. Wind Speed, March 1, 2007 ­ May 31, 2007 January 30, 2008 Renewable Energy Research

Massachusetts at Amherst, University of

226

Kolmogorov versus Iroshnikov-Kraichnan spectra: Consequences for ion heating in the solar wind  

E-Print Network (OSTI)

Whether the phenomenology governing MHD turbulence is Kolmogorov or Iroshnikov-Kraichnan (IK) remains an open question, theoretically as well as observationally. The ion heating profile observed in the solar wind provides a quantitative, if indirect, observational constraint on the relevant phenomenology. Recently, a solar wind heating model based on Kolmogorov spectral scaling has produced reasonably good agreement with observations, provided the effect of turbulence generation due to pickup ions is included in the model. Without including the pickup ion contributions, the Kolmogorov scaling predicts a proton temperature profile that decays too rapidly beyond a radial distance of 15 AU. In the present study, we alter the heating model by applying an energy cascade rate based on IK scaling, and show that the model yields higher proton temperatures, within the range of observations, with or without the inclusion of the effect due to pickup ions. Furthermore, the turbulence correlation length based on IK scalin...

Ng, C S; Munsi, D; Isenberg, P A; Smith, C W; 10.1029/2009JA014377

2011-01-01T23:59:59.000Z

227

Diurnal and seasonal variations of wind farm impacts on land surface temperature over western Texas  

E-Print Network (OSTI)

industry has installed a total of 46,919 megawatts (MW) of capac- ity, making it second in the world behind, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA e energy is among the world's fastest growing sources of energy. Through the end of 2011, the US wind

Zhou, Liming

228

Comparison of Wind Profiler and Aircraft Wind Measurements at Chebogue Point, Nova Scotia  

Science Conference Proceedings (OSTI)

In August 1993, a 915-MHz boundary layer wind-profiling radar was deployed at Chebogue Point, Nova Scotia, to provide wind, turbulence, and boundary layer structure information for the North Atlantic Regional Experiment summer 1993 intensive ...

Wayne M. Angevine; J. Ian Macpherson

1995-04-01T23:59:59.000Z

229

A Method for Combining Radiances and Wind Shear to Define the Temperature Structure of the Atmosphere  

Science Conference Proceedings (OSTI)

The retrieval of temperature from satellite-observed radiances has traditionally been addressed as a one-dimensional or columnar problem which uses a guess profile of temperature. In this study, the traditional approach is augmented by ...

John Lewis; Christopher Hayden; John Derber

1989-06-01T23:59:59.000Z

230

NREL: Learning - Wind Energy Basics: How Wind Turbines Work  

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

Wind Energy Basics: How Wind Turbines Work Wind Energy Basics: How Wind Turbines Work We have been harnessing the wind's energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill's modern equivalent-a wind turbine-can use the wind's energy to generate electricity. Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor. A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure

231

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

232

Numerical Simulation of ANATEX Tracer Data Using a Turbulence Closure Model for Long-Range Dispersion  

Science Conference Proceedings (OSTI)

A long-range transport model based on turbulence closure concepts is described. The model extends the description of planetary boundary layer turbulent diffusion to the larger scales and uses statistical wind information to predict contaminant ...

R. I. Sykes; S. F. Parker; D. S. Henn; W. S. Lewellen

1993-05-01T23:59:59.000Z

233

Turbulence Structure of the Hurricane Boundary Layer between the Outer Rainbands  

Science Conference Proceedings (OSTI)

As part of the Coupled Boundary Layers Air–Sea Transfer (CBLAST)-Hurricane program, flights were conducted to directly measure turbulent fluxes and turbulence properties in the high-wind boundary layer of hurricanes between the outer rainbands. ...

Jun A. Zhang; William M. Drennan; Peter G. Black; Jeffrey R. French

2009-08-01T23:59:59.000Z

234

LIDAR Wind Speed Measurements of Evolving Wind Fields  

DOE Green Energy (OSTI)

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

Simley, E.; Pao, L. Y.

2012-07-01T23:59:59.000Z

235

LIDAR Wind Speed Measurements of Evolving Wind Fields  

SciTech Connect

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

Simley, E.; Pao, L. Y.

2012-07-01T23:59:59.000Z

236

Wind Energy Assessment Study for Nevada -- Tall Tower Deployment (Stone Cabin): 26 June 2005 - 31 December 2007  

DOE Green Energy (OSTI)

The objective of this work effort was to characterize wind shear and turbulence for representative wind-developable areas in Nevada.

Koracin, D.; Reinhardt, R.; McCurdy, G.; Liddle, M.; McCord, T.; Vellore, R.; Minor, T.; Lyles, B.; Miller, D.; Ronchetti, L.

2009-12-01T23:59:59.000Z

237

RESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine  

E-Print Network (OSTI)

RESEARCH ARTICLE Dynamic wind loads and wake characteristics of a wind turbine model of the unsteady vortex and turbulent flow structures in the near wake of a horizontal axis wind turbine model.e., aerodynamic forces and bending moments) acting on the wind turbine model by using a high-sensitive force

Hu, Hui

238

Snow Temperature Changes within a Seasonal Snowpack and their Relationship to Turbulent Fluxes of Sensible and Latent Heat  

Science Conference Proceedings (OSTI)

Snowpack temperatures from a subalpine forest below Niwot Ridge, Colorado are examined with respect to atmospheric conditions and the 30-min above-canopy and subcanopy eddy covariance fluxes of sensible Qh and latent Qe heat. In the lower snowpack,...

Sean P. Burns; Noah P. Molotch; Mark W. Williams; John F. Knowles; Brian Seok; Russell K. Monson; Andrew A. Turnipseed; Peter D. Blanken

239

Towns across Massachusetts are considering wind power, not only because it is one of the cleanest,  

E-Print Network (OSTI)

of energy captured from the wind and electricity produced. The quality of a wind site depends on may things of the wind and create turbulence. Turbulence reduces the amount of energy that can be captured and can Power: Siting in Communities Wind Power on the Community Scale Renewable Energy Research Laboratory

Massachusetts at Amherst, University of

240

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

242

NREL Develops Simulations for Wind Plant Power and Turbine Loads...  

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

loading due to wake turbulence. The current state of knowledge concerning wind turbine wakes and how they interact with other turbines and the atmospheric boundary layer is...

243

3D Simulation of a 5MW Wind Turbine.  

E-Print Network (OSTI)

??In the present work, the influence of turbulence and gravity forces on the tower and the rotor of a 5MW onshore wind turbine has been… (more)

Namiranian, Abtin

2011-01-01T23:59:59.000Z

244

An Objective Clear-Air Turbulence Forecasting Technique: Verification and Operational Use  

Science Conference Proceedings (OSTI)

An objective technique for forecasting clear-air turbulence (CAT) is described. An index is calculated based on the product of horizontal deformation and vertical wind shear derived from numerical model forecast winds aloft. The forecast ...

Gary P. Ellrod; David I. Knapp

1992-03-01T23:59:59.000Z

245

LIDAR wind speed measurements of evolving wind fields  

E-Print Network (OSTI)

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor’s frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor’s hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios. Nomenclature a decay parameter for exponential coherence al decrement parameter for transverse coherence (l ? {u, v, w}) bl offset parameter for transverse coherence (l ? {u, v, w}) D longitudinal distance between two points or measurement preview distance F focal distance f frequency (Hz) ? LIDAR measurement angle off of longitudinal direction k wind velocity wavenumber (m?1) ? wavelength (m) R range along LIDAR beam r scan radius for spinning LIDAR scenario ri,j distance between two points in the yz plane U mean wind speed (m/s) ?i,j average mean wind speed between two points in the yz plane ? azimuth angle in the rotor plane ?2 xy(f) Coherence between signals x and y

Eric Simley; Lucy Y. Pao; Neil Kelley; Bonnie Jonkman; Rod Frehlich

2012-01-01T23:59:59.000Z

246

Estimators for the Standard Deviation of Horizontal Wind Direction  

Science Conference Proceedings (OSTI)

The standard deviation of horizontal wind direction is a central quantity in the description of atmospheric turbulence and of great practical use in dispersion models. As horizontal wind direction is a circular variable, its standard deviation ...

Rudolf O. Weber

1997-10-01T23:59:59.000Z

247

NREL Studies Wind Farm Aerodynamics to Improve Siting (Fact Sheet)  

DOE Green Energy (OSTI)

NREL researchers have used high-tech instruments and high-performance computing to understand atmospheric turbulence and turbine wake behavior in order to improve wind turbine design and siting within wind farms.

Not Available

2012-04-01T23:59:59.000Z

248

Comparison of Wind Monitoring Systems. Pad II: Doppley. Sodars  

Science Conference Proceedings (OSTI)

Measurements of wind speed, wind direction, and the vertical component of turbulence, from four different commercially available Doppler sodars, are compared with similar measurements from in situ sensors on a 300 m instrumented tower. Results ...

P. L. Finkelstein; J. C. Kaimal; J. E. Gaynor; M. E. Graves; T. J. Lockhart

1986-12-01T23:59:59.000Z

249

WIND DATA REPORT Ragged Mt Maine  

E-Print Network (OSTI)

Energy Research Laboratory (RERL) at the University of Massachusetts, Amherst. This report covers wind Average Wind Speeds, September 1, 2007 ­ November 30, 2007. January 22, 2008 Renewable Energy Research ­ Turbulence Intensity vs. Wind Speed, September 1, 2007 ­ November 30, 2007. January 22, 2008 Renewable Energy

Massachusetts at Amherst, University of

250

Resolved turbulence characteristics in large-eddy simulations nested within mesoscale simulations using the Weather Research and Forecasting model  

Science Conference Proceedings (OSTI)

One-way concurrent nesting within the Weather Research and Forecasting (WRF) model is examined for conducting large-eddy simulations (LES) nested within mesoscale simulations. Wind speed, spectra, and resolved turbulent stresses and turbulence ...

Jeff Mirocha; Branko Kosovi?; Gokhan Kirkil

251

Drag Anemometer Measurements of Turbulence over a Vegetated Surface  

Science Conference Proceedings (OSTI)

Turbulent fluctuations of vertical wind and fluxes of momentum, sensible heat and latent heat measured with a drag anemometer are compared to like data measured with other instruments. Means of the measured parameters agreed well with energy ...

T. Grayson Redford Jr.; Shashi B. Verma; Norman J. Rosenberg

1981-10-01T23:59:59.000Z

252

A Climatology of Turbulent Dispersion in the Troposphere  

Science Conference Proceedings (OSTI)

The authors present properties of turbulent, meridional mixing along isentropic surfaces within the troposphere. Twice-daily wind fields analyses from the European Centre for Medium-Range Weather Forecasts numerical weather prediction model for ...

Matthew Huber; James C. McWilliams; Michael Ghil

2001-08-01T23:59:59.000Z

253

Stability and Turbulence in the Atmospheric Boundary Layer: A Comparison of Remote Sensing and Tower Observations  

Science Conference Proceedings (OSTI)

When monitoring winds and atmospheric stability for wind energy applications, remote sensing instruments present some advantages to in-situ instrumentation such as larger vertical extent, in some cases easy installation and maintenance, measurements of vertical humidity profiles throughout the boundary layer, and no restrictions on prevailing wind directions. In this study, we compare remote sensing devices, Windcube lidar and microwave radiometer, to meteorological in-situ tower measurements to demonstrate the accuracy of these measurements and to assess the utility of the remote sensing instruments in overcoming tower limitations. We compare temperature and wind observations, as well as calculations of Brunt-Vaisala frequency and Richardson numbers for the instrument deployment period in May-June 2011 at the U.S. Department of Energy National Renewable Energy Laboratory's National Wind Technology Center near Boulder, Colorado. The study reveals that a lidar and radiometer measure wind and temperature with the same accuracy as tower instruments, while also providing advantages for monitoring stability and turbulence. We demonstrate that the atmospheric stability is determined more accurately when the liquid-water mixing ratio derived from the vertical humidity profile is considered under moist-adiabatic conditions.

Friedrich, K.; Lundquist, J. K.; Aitken, M.; Kalina, E. A.; Marshall, R. F.

2012-01-01T23:59:59.000Z

254

20th Century Reanalysis Project Ensemble Gateway: 56 Estimates of World Temperature, Pressure, Humidity, and Wind, 1871-2010  

DOE Data Explorer (OSTI)

This site provides data from the 20th Century Reanalysis Project, offering temperature, pressure, humidity, and wind predictions in 200 km sections all around the earth from 1871 to 2010, every 6 hours, based on historical data. The ensemble mean and standard deviation for each value were calculated over a set of 56 simulations. Data for each of the 56 ensemble members are included here. The dataset consists of files in netCDF 4 format that are available for download from the National Energy Research. The goal of the 20th Century Reanalysis Project is to use a Kalman filter-based technique to produce a global trophospheric circulation dataset at four-times-daily resolution back to 1871. The only dataset available for the early 20th century consists of error-ridden hand-drawn analyses of the mean sea level pressure field over the Northern Hemisphere. Modern data assimilation systems have the potential to improve upon these maps, but prior to 1948, few digitized upper-air sounding observations are available for such a reanalysis. The global tropospheric circulation dataset will provide an important validation check on the climate models used to make 21st century climate projections....[copied from http://portal.nersc.gov/project/20C_Reanalysis/

255

Wind resource assessment with a mesoscale non-hydrostatic model  

E-Print Network (OSTI)

Wind resource assessment with a mesoscale non- hydrostatic model Vincent Guénard, Center for Energy is developed for assessing the wind resource and its uncertainty. The work focuses on an existing wind farm mast measurements. The wind speed and turbulence fields are discussed. It is shown that the k

Paris-Sud XI, Université de

256

Fifteen Lectures on Laminar and Turbulent Combustion  

E-Print Network (OSTI)

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

Peters, Norbert

257

Yaglom law in the expanding solar wind  

E-Print Network (OSTI)

We study the Yaglom law, which relates the mixed third order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two scales expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Els\\"asser fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.

Gogoberidze, G; Carbone, V

2013-01-01T23:59:59.000Z

258

Formation of Jets by Baroclinic Turbulence  

Science Conference Proceedings (OSTI)

Turbulent fluids are frequently observed to spontaneously self-organize into large spatial-scale jets; geophysical examples of this phenomenon include the Jovian banded winds and the earth’s polar-front jet. These relatively steady large-scale ...

Brian F. Farrell; Petros J. Ioannou

2008-11-01T23:59:59.000Z

259

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;

260

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

The Use and Analysis of Profiler Winds to Derive Mesoscale Height and Temperature Fields: Simulation and Real-Data Experiments  

Science Conference Proceedings (OSTI)

Conventional synoptic rawinsonde data do not have a fine enough temporal or spatial resolution to accurately resolve mesoscale features. Profiling networks are one potential source of these data although they provide only wind information. A ...

Jennifer M. Cram; Michael L. Kaplan; Craig A. Mattocks; John W. Zack

1991-04-01T23:59:59.000Z

262

An Assessment of the Sea Surface Temperature Influence on Surface Wind Stress in Numerical Weather Prediction and Climate Models  

Science Conference Proceedings (OSTI)

The ability of six climate models to capture the observed coupling between SST and surface wind stress in the vicinity of strong midlatitude SST fronts is analyzed. The analysis emphasizes air–sea interactions associated with ocean meanders in ...

Eric D. Maloney; Dudley B. Chelton

2006-06-01T23:59:59.000Z

263

Rotationally sampled wind characteristics and correlations with MOD-OA wind turbine response  

SciTech Connect

This report presents results of a comprehensive wind and wind turbine measurement program: the Clayton, New Mexico, vertical plane array/MOD-OA project. In this experiment, the turbulent wind was measured for a large array of fixed anemometers located two blade diameters upwind of a 200-kW horizontal-axis wind turbine (HAWT). Simultaneously, key wind turbine response parameters were also measured. The first of two major objectives of this experiment was to determine the turbulent wind, rotationally sampled to emulate the motion of the wind turbine blade, for the range of different wind speeds and stability classes actually experienced by the wind turbine. The second major objective was to correlate this rotationally sampled wind with the wind turbine blade stress and power, in order to assess the usefulness of the wind measurements for wind turbine loads testing a prediction. Time series of rotationally sampled winds and wind turbine blade bending moments and power were converted to frequency spectra using Fourier transform techniques. These spectra were used as the basis for both qualitative and quantitative comparisons among the various cases. A quantitative comparison between the rotationally sampled wind input and blade bending response was made, using the Fourier spectra to estimate the blade transfer function. These transfer functions were then used to calculate an approximate damping coefficient for the MOD-OA fiberglass blade.

George, R.L.; Connell, J.R.

1984-09-01T23:59:59.000Z

264

Wind Electrolysis: Hydrogen Cost Optimization  

DOE Green Energy (OSTI)

This report describes a hydrogen production cost analysis of a collection of optimized central wind based water electrolysis production facilities. The basic modeled wind electrolysis facility includes a number of low temperature electrolyzers and a co-located wind farm encompassing a number of 3MW wind turbines that provide electricity for the electrolyzer units.

Saur, G.; Ramsden, T.

2011-05-01T23:59:59.000Z

265

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

266

Effects of Changing Atmospheric Conditions on Wind Turbine Performance (Poster)  

SciTech Connect

Multi-megawatt, utility-scale wind turbines operate in turbulent and dynamic winds that impact turbine performance in ways that are gradually becoming better understood. This poster presents a study made using a turbulent flow field simulator (TurbSim) and a Turbine aeroelastic simulator (FAST) of the response of a generic 1.5 MW wind turbine to changing inflow. The turbine power output is found to be most sensitive to wind speed and turbulence intensity, but the relationship depends on the wind speed with respect to the turbine's rated wind speed. Shear is found to be poorly correlated to power. A machine learning method called 'regression trees' is used to create a simple model of turbine performance that could be used as part of the wind resource assessment process. This study has used simple flow fields and should be extended to more complex flows, and validated with field observations.

Clifton, A.

2012-12-01T23:59:59.000Z

267

Real-Time Ocean Wind Vector Retrieval from Marine Radar Image Sequences Acquired at Grazing Angle  

Science Conference Proceedings (OSTI)

This paper proposes a novel algorithm for retrieving the ocean wind vector from marine radar image sequences in real time. It is presented as an alternative to mitigate anemometer problems, such as blockage, shadowing, and turbulence. Since wind ...

Raul Vicen-Bueno; Jochen Horstmann; Eric Terril; Tony de Paolo; Jens Dannenberg

2013-01-01T23:59:59.000Z

268

Model-Simulated Influences of Shelterbelt Shape on Wind-Sheltering Efficiency  

Science Conference Proceedings (OSTI)

The authors report results of a numerical model used to simulate wind and turbulence fields for porous, living shelterbelts with seven different cross-sectional shapes. The simulations are consistent with results of Woodruff and Zingg whose wind-...

Hao Wang; E. S. Takle

1997-06-01T23:59:59.000Z

269

Modeling of wind and radar for simulation in four-dimensional navigation environment  

E-Print Network (OSTI)

Disturbances affecting time control precision in four-dimension navigation are modeled. Several models of wind and turbulence from the ground to ten thousand feet are developed. A distinction is made between wind mean and ...

Malherbe, Gerard Andre

1976-01-01T23:59:59.000Z

270

Linear Wind Farm Layout Optimization through Computational Intelligence  

Science Conference Proceedings (OSTI)

The optimal positioning of wind turbines, even in one dimension, is a problem with no analytical solution. This article describes the application of computational intelligence techniques to solve this problem. A systematic analysis of the optimal positioning ... Keywords: Far Wake Effects, Genetic Algorithms, Optimization, Simulated Annealing, Sitting, Turbulence and Roughness Length, Wind Farm Layout, Wind Turbines

José-Francisco Herbert-Acero; Jorge-Rodolfo Franco-Acevedo; Manuel Valenzuela-Rendón; Oliver Probst-Oleszewski

2009-11-01T23:59:59.000Z

271

WIND DATA REPORT Scituate Waste Water Treatment Plant, MA  

E-Print Network (OSTI)

Distributions Figure 3 ­ Wind Speed Distribution, March 1, 2007 ­ May 31, 2007 July 16, 2007 Renewable Energy Figure 5 ­ Diurnal Wind Speeds, March 1, 2007 ­ May 31, 2007 July 16, 2007 Renewable Energy Research ­ Turbulence Intensity vs. Wind Speed, March 1, 2007 ­ May 31, 2007 July 16, 2007 Renewable Energy Research

Massachusetts at Amherst, University of

272

Resolving Difficult Issues Of Wind Power Micrositing In Complex  

E-Print Network (OSTI)

Micrositing of wind turbines in complex terrain is tricky game, and many of the current siting methods and tools, while useful and improving, remain inadequate to the task in extreme terrain. As a consequence, there are numerous wind turbine installations that are buffeted by damaging turbulence or are faced with suboptimal wind energy performance.

Terrain Session Resource; Russell G. Derickson A; Michael Mcdiarmid B; Brad C. Cochran C; Jon A. Peterka D; Russell G. Derickson A; Michael Mcdiarmid B; Brad C. Cochran C; Jon A. Peterka D

2004-01-01T23:59:59.000Z

273

Ris-R-1239(EN) Wind Energy Department  

E-Print Network (OSTI)

Risø-R-1239(EN) Wind Energy Department: Scientific and Technical Progress 1999 - 2000 Birthe The activities of the Wind Energy Department fall within boundary layer meteorology, atmospheric turbulence-R-1239(EN) 3 Contents 1 Introduction 5 2 The Department of Wind Energy and Atmospheric Physics 5 3

274

NREL researchers are the first to use a high-performance com-puting tool for a large-eddy simulation of an entire wind plant.  

E-Print Network (OSTI)

an existing wind plant, augmenting previous studies of wind plant subsets. Wind turbines extract energy from the wind's flow, and as a byproduct they create a wake that trails behind them. If wind turbines mechanical loading due to wake turbulence.The current state of knowledge concerning wind turbine wakes

275

Analysis of Wind Speed Measurements using Continuous Wave LIDAR for Wind Turbine Control ?†  

E-Print Network (OSTI)

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurate the incoming wind field can be measured. This study examines the accuracy of different measurement scenarios that rely on coherent continuouswave Doppler LIDAR systems to determine their applicability to feedforward control. In particular, the impacts of measurement range and angular offset from the wind direction are studied for various wind conditions. A realistic case involving a scanning LIDAR unit mounted in the spinner of a wind turbine is studied in depth, with emphasis on choices for scan radius and preview distance. The effects of turbulence parameters on measurement accuracy are studied as well. Nomenclature d measurement preview distance F focal distance k wind velocity wavenumber (m?1) r scan radius for spinning LIDAR RMS root mean square ?u standard deviation of u component of wind velocity TI turbulence intensity ? LIDAR measurement angle ? mean u wind speed u ? friction velocity U ? D average friction velocity over rotor disk ? angle between laser and wind velocity vector ? angle in the rotor plane ? rotational rate of spinning LIDAR

Eric Simley; Lucy Y. Pao; Rod Frehlich; Bonnie Jonkman; Neil Kelley

2011-01-01T23:59:59.000Z

276

Simulation of winds as seen by a rotating vertical axis wind turbine blade  

DOE Green Energy (OSTI)

The objective of this report is to provide turbulent wind analyses relevant to the design and testing of Vertical Axis Wind Turbines (VAWT). A technique was developed for utilizing high-speed turbulence wind data from a line of seven anemometers at a single level to simulate the wind seen by a rotating VAWT blade. Twelve data cases, representing a range of wind speeds and stability classes, were selected from the large volume of data available from the Clayton, New Mexico, Vertical Plane Array (VPA) project. Simulations were run of the rotationally sampled wind speed relative to the earth, as well as the tangential and radial wind speeds, which are relative to the rotating wind turbine blade. Spectral analysis is used to compare and assess wind simulations from the different wind regimes, as well as from alternate wind measurement techniques. The variance in the wind speed at frequencies at or above the blade rotation rate is computed for all cases, and is used to quantitatively compare the VAWT simulations with Horizontal Axis Wind Turbine (HAWT) simulations. Qualitative comparisons are also made with direct wind measurements from a VAWT blade.

George, R.L.

1984-02-01T23:59:59.000Z

277

LIDAR Wind Speed Measurements of Evolving Wind Fields  

Science Conference Proceedings (OSTI)

Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems that are designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed the validity of physicist G.I. Taylor's 1938 frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations using the National Renewable Energy Laboratory's (NREL's) 5-megawatt turbine model to create a more realistic measurement model. A simple model of wind evolution was applied to a frozen wind field that was used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements were also evaluated using a large eddy simulation (LES) of a stable boundary layer that was provided by the National Center for Atmospheric Research. The LIDAR measurement scenario investigated consists of a hub-mounted LIDAR that scans a circle of points upwind of the turbine in order to estimate the wind speed component in the mean wind direction. Different combinations of the preview distance that is located upwind of the rotor and the radius of the scan circle were analyzed. It was found that the dominant source of measurement error for short preview distances is the detection of transverse and vertical wind speeds from the line-of-sight LIDAR measurement. It was discovered in previous studies that, in the absence of wind evolution, the dominant source of error for large preview distances is the spatial averaging caused by the LIDAR's sampling volume. However, by introducing wind evolution, the dominant source of error for large preview distances was found to be the coherence loss caused by evolving turbulence. Different measurement geometries were compared using the bandwidth for which the measurement coherence remained above 0.5 and also the area under the measurement coherence curve. Results showed that, by increasing the intensity of wind evolution, the measurement coherence decreases. Using the coherence bandwidth metric, the optimal preview distance for a fixed-scan radius remained almost constant for low and moderate amounts of wind evolution. For the wind field with the simple wind evolution model introduced, the optimal preview distance for a scan radius of 75% blade span (47.25 meters) was found to be 80 meters. Using the LES wind field, the optimal preview distance was 65 meters. When comparing scan geometries using the area under the coherence curve, results showed that, as the intensity of wind evolution increases, the optimal preview distance decreases.

Simley, E.; Pao, L. Y.; Kelley, N.; Jonkman, B.; Frehlich, R.

2012-01-01T23:59:59.000Z

278

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

279

Evening Temperature Rises on Valley Floors and Slopes: Their Causes and Their Relationship to the Thermally Driven Wind System  

Science Conference Proceedings (OSTI)

At slope and valley floor sites in the Owens Valley of California, the late afternoon near-surface air temperature decline is often followed by a temporary temperature rise before the expected nighttime cooling resumes. The spatial and temporal ...

C. David Whiteman; Sebastian W. Hoch; Gregory S. Poulos

2009-04-01T23:59:59.000Z

280

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

282

Extreme Winds and Wind Effects on Structures  

Science Conference Proceedings (OSTI)

Extreme Winds and Wind Effects on Structures. The Engineering ... section. I. Extreme Winds: ... II. Wind Effects on Buildings. Database ...

2013-01-17T23:59:59.000Z

283

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

284

Direct Numerical Simulation of Differential Scalar Diffusion in Three-Dimensional Stratified Turbulence  

Science Conference Proceedings (OSTI)

The potential for differential turbulent transport of oceanic temperature (T) and salinity () is explored using three-dimensional direct numerical simulations of decaying stratified turbulence. The simulations employ a realistic molecular ...

Ann E. Gargett; William J. Merryfield; Greg Holloway

2003-08-01T23:59:59.000Z

285

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

286

Direct Numerical Simulation of Differential Scalar Diffusion in Three-Dimensional Stratified Turbulence  

Science Conference Proceedings (OSTI)

The potential for differential turbulent transport of oceanic temperature (T) and salinity (S) is explored using three-dimensional direct numerical simulations of decaying stratified turbulence. The simulations employ a realistic molecular ...

Ann E. Gargett; William J. Merryfield; Greg Holloway

2003-08-01T23:59:59.000Z

287

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

288

Influence of a New Turbulence Regime on the Global Air–Sea Heat Fluxes  

Science Conference Proceedings (OSTI)

Recent research has found that boundary layer turbulence changes its organization as the stratification approaches neutral from the unstable side. When the thermal forcing weakens in combination with wind speed above approximately 10 m s?1, ...

Erik Sahlée; Ann-Sofi Smedman; Anna Rutgersson; Ulf Högström

2008-11-01T23:59:59.000Z

289

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

290

Turbulent Fluxes in the Hurricane Boundary Layer. Part II: Latent Heat Flux  

Science Conference Proceedings (OSTI)

As part of the recent ONR-sponsored Coupled Boundary Layer Air–Sea Transfer (CBLAST) Departmental Research Initiative, an aircraft was instrumented to carry out direct turbulent flux measurements in the high wind boundary layer of a hurricane. ...

William M. Drennan; Jun A. Zhang; Jeffrey R. French; Cyril McCormick; Peter G. Black

2007-04-01T23:59:59.000Z

291

Equilibrium Geostrophic Turbulence I: A Reference Solution in a ?-Plane Channel  

Science Conference Proceedings (OSTI)

A numerical solution is calculated for quasi-geostrophic, adiabatic, baroclinic, wind-driven flow in a ? channel. The rates of driving and dissipation are such that the solution is turbulent in equilibrium. The equilibrium state is characterized ...

James C. McWilliams; Julianna H. S. Chow

1981-07-01T23:59:59.000Z

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

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

294

Atmospheric Stability Impacts on Power Curves of Tall Wind Turbines - An Analysis of a West Coast North American Wind Farm  

SciTech Connect

Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow and turbulence at these heights in the boundary layer. Depending on whether the boundary layer is stable, neutral, or convective, the mean wind speed, direction, and turbulence properties may vary greatly across the tall turbine swept area (40 to 120 m AGL). This variability can cause tall turbines to produce difference amounts of power during time periods with identical hub height wind speeds. Using meteorological and power generation data from a West Coast North American wind farm over a one-year period, our study synthesizes standard wind park observations, such as wind speed from turbine nacelles and sparse meteorological tower observations, with high-resolution profiles of wind speed and turbulence from a remote sensing platform, to quantify the impact of atmospheric stability on power output. We first compare approaches to defining atmospheric stability. The standard, limited, wind farm operations enable the calculation only of a wind shear exponent ({alpha}) or turbulence intensity (I{sub U}) from cup anemometers, while the presence at this wind farm of a SODAR enables the direct observation of turbulent kinetic energy (TKE) throughout the turbine rotor disk. Additionally, a nearby research meteorological station provided observations of the Obukhov length, L, a direct measure of atmospheric stability. In general, the stability parameters {alpha}, I{sub U}, and TKE are in high agreement with the more physically-robust L, with TKE exhibiting the best agreement with L. Using these metrics, data periods are segregated by stability class to investigate power performance dependencies. Power output at this wind farm is highly correlated with atmospheric stability during the spring and summer months, while atmospheric stability exerts little impact on power output during the winter and autumn periods. During the spring and summer seasons, power output for a given wind speed was significantly higher during stable conditions and significantly lower during strongly convective conditions: power output differences approached 20% between stable and convective regimes. The dependency of stability on power output was apparent only when both turbulence and the shape of the wind speed profile were considered. Turbulence is one of the mechanisms by which atmospheric stability affects a turbine's power curve at this particular site, and measurements of turbulence can yield actionable insights into wind turbine behavior.

Wharton, S; Lundquist, J K

2010-02-22T23:59:59.000Z

295

Atmospheric Stability Impacts on Power Curves of Tall Wind Turbines - An Analysis of a West Coast North American Wind Farm  

SciTech Connect

Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow and turbulence at these heights in the boundary layer. Depending on whether the boundary layer is stable, neutral, or convective, the mean wind speed, direction, and turbulence properties may vary greatly across the tall turbine swept area (40 to 120 m AGL). This variability can cause tall turbines to produce difference amounts of power during time periods with identical hub height wind speeds. Using meteorological and power generation data from a West Coast North American wind farm over a one-year period, our study synthesizes standard wind park observations, such as wind speed from turbine nacelles and sparse meteorological tower observations, with high-resolution profiles of wind speed and turbulence from a remote sensing platform, to quantify the impact of atmospheric stability on power output. We first compare approaches to defining atmospheric stability. The standard, limited, wind farm operations enable the calculation only of a wind shear exponent ({alpha}) or turbulence intensity (I{sub U}) from cup anemometers, while the presence at this wind farm of a SODAR enables the direct observation of turbulent kinetic energy (TKE) throughout the turbine rotor disk. Additionally, a nearby research meteorological station provided observations of the Obukhov length, L, a direct measure of atmospheric stability. In general, the stability parameters {alpha}, I{sub U}, and TKE are in high agreement with the more physically-robust L, with TKE exhibiting the best agreement with L. Using these metrics, data periods are segregated by stability class to investigate power performance dependencies. Power output at this wind farm is highly correlated with atmospheric stability during the spring and summer months, while atmospheric stability exerts little impact on power output during the winter and autumn periods. During the spring and summer seasons, power output for a given wind speed was significantly higher during stable conditions and significantly lower during strongly convective conditions: power output differences approached 20% between stable and convective regimes. The dependency of stability on power output was apparent only when both turbulence and the shape of the wind speed profile were considered. Turbulence is one of the mechanisms by which atmospheric stability affects a turbine's power curve at this particular site, and measurements of turbulence can yield actionable insights into wind turbine behavior.

Wharton, S; Lundquist, J K

2010-02-22T23:59:59.000Z

296

Observations of temperature, wind, cirrus, and trace gases in the tropical tropopause transition layer during the MJO  

Science Conference Proceedings (OSTI)

Satellite observations of temperature, optically thin cirrus clouds, and trace gases derived from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite ...

Katrina S. Virts; John M. Wallace

297

Use of WindSat to Extend a Microwave-Based Daily Optimum Interpolation Sea Surface Temperature Time Series  

Science Conference Proceedings (OSTI)

The NOAA ¼° daily optimum interpolation sea surface temperature analysis (DOISST) is available either as a 31-yr (from 1981 onward) time series based on Advanced Very High Resolution Radiometer (AVHRR) observations or as a 9-yr (2002–11) time ...

Viva F. Banzon; Richard W. Reynolds

2013-04-01T23:59:59.000Z

298

Song of the Wind  

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

Song of the Wind Song of the Wind Nature Bulletin No. 318-A October 26, 1968 Forest Preserve District of Cook County Richard B. Ogilvie, President Roland F. Eisenbeis, Supt. of Conservation SONG OF THE WIND The wind is simply air in motion. Air has substance like wood or water, it has pressure, it can acquire heat and hold a temperature, and it can travel from place to place.... The air which affects our lives is a layer seven or eight miles thick, called the troposphere, which is next to the earth. This air has pressure (14.7 pounds per square inch at sea level) and when various factors, one of which is temperature, cause changes in this pressure, the air starts moving. We cannot see it. We can hear it. The song of the wind is the most wonderful music on earth, and at times the most terrifying in its angry moments.

299

EERE: Wind  

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

EERE: Buildings The U.S. Department of Energy funds R&D to develop wind energy. Learn about the DOE Wind Program, how to use wind energy and get financial incentives, and access...

300

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'...

Vazquez-Semadeni, Enrique

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

WIND ENERGY Wind Energ. (2012)  

E-Print Network (OSTI)

WIND ENERGY Wind Energ. (2012) Published online in Wiley Online Library (wileyonlinelibrary since energy production depends non-linearly on wind speed (U ), and wind speed observa- tions for the assessment of future long-term wind supply A. M. R. Bakker1 , B. J. J. M. Van den Hurk1 and J. P. Coelingh2 1

Haak, Hein

302

Temporal trend analyses of alpine data using North American Regional Reanalysis and in situ data: temperature, wind speed, precipitation, and derived blowing snow  

Science Conference Proceedings (OSTI)

Across the globe wind speed trends have shown a slight decline for in situ meteorological datasets. Yet few studies have assessed long-term wind speed trends for alpine regions or how such trends could influence snow transport and distribution. ...

Jamie D. Fuller; Nolan Doesken; Kelly Elder; Melinda Laituri; Glen E. Liston

303

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 *...

304

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

305

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

306

On the Role of Sea Surface Temperature Gradients in Forcing Low-Level Winds and Convergence in the Tropics  

Science Conference Proceedings (OSTI)

We examine the importance of pressure gradients due to surface temperature gradients to low-level (p ? 700 mb) flow and convergence in the tropics over time scales 1 month. The latter plays a crucial role in determining the distribution of ...

Richard S. Lindzen; Sumant Nigam

1987-09-01T23:59:59.000Z

307

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

308

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

309

Theoretical analysis of acceleration measurements in a model of an operating wind turbine.  

Science Conference Proceedings (OSTI)

Wind loading from turbulence and gusts can cause damage in horizontal axis wind turbines. These unsteady loads and the resulting damage initiation and propagation are difficult to predict. Unsteady loads enter at the rotor and are transmitted to the drivetrain. The current generation of wind turbine has drivetrain-mounted vibration and bearing temperature sensors, a nacelle-mounted inertial measurement unit, and a nacelle-mounted anemometer and wind vane. Some advanced wind turbines are also equipped with strain measurements at the root of the rotor. This paper analyzes additional measurements in a rotor blade to investigate the complexity of these unsteady loads. By identifying the spatial distribution, amplitude, and frequency bandwidth of these loads, design improvements could be facilitated to reduce uncertainties in reliability predictions. In addition, dynamic load estimates could be used in the future to control high-bandwidth aerodynamic actuators distributed along the rotor blade to reduce the saturation of slower pitch actuators currently used for wind turbine blades. Local acceleration measurements are made along a rotor blade to infer operational rotor states including deflection and dynamic modal contributions. Previous work has demonstrated that acceleration measurements can be experimentally acquired on an operating wind turbine. Simulations on simplified rotor blades have also been used to demonstrate that mean blade loading can be estimated based on deflection estimates. To successfully apply accelerometers in wind turbine applications for load identification, the spectral and spatial characteristics of each excitation source must be understood so that the total acceleration measurement can be decomposed into contributions from each source. To demonstrate the decomposition of acceleration measurements in conjunction with load estimation methods, a flexible body model has been created with MSC.ADAMS{copyright} The benefit of using a simulation model as opposed to a physical experiment to examine the merits of acceleration-based load identification methods is that models of the structural dynamics and aerodynamics enable one to compare estimates of the deflection and loading with actual values. Realistic wind conditions are applied to the wind turbine and used to estimate the operational displacement and acceleration of the rotor. The per-revolution harmonics dominate the displacement and acceleration response. Turbulent wind produces broadband excitation that includes both the harmonics and modal vibrations, such as the tower modes. Power Spectral Density estimates of the acceleration along the span of the rotor blades indicate that the edge modes may be coupled to the second harmonic.

Adams, Douglas E. (Purdue University, Lafayette, IN); Rumsey, Mark Allen; White, Jonathan Randall

2010-04-01T23:59:59.000Z

310

An Analysis of Low-Frequency Maritime Atmospheric Turbulence  

Science Conference Proceedings (OSTI)

New data are presented for the spectrum of turbulent wind energy under maritime conditions in the frequency region 1.0–0.03 mHz. The corresponding measurements were made at five levels on a mast 46 m high on a small islet off the coast of central ...

Johannes Gjerstad; Svein Erik Aasen; Helge I. Andersson; Iver Brevik; Jørgen Løvseth

1995-08-01T23:59:59.000Z

311

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

312

Viscous Dissipation of Turbulence Kinetic Energy in Storms  

Science Conference Proceedings (OSTI)

In this note the magnitude of the viscous dissipation of turbulence kinetic energy in the surface layer of storms is investigated. It is shown that the layer-integrated dissipative heating is a cubic function of the wind speed. The magnitude of ...

Steven Businger; Joost A. Businger

2001-12-01T23:59:59.000Z

313

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

314

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

315

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

316

Near-Neutral Surface Layer Turbulence at the Boulder Atmospheric Observatory Tower: Evidence of Increasing Vertical Turbulence with Height  

Science Conference Proceedings (OSTI)

Wind and turbulence profiles were analyzed during breezy, near-neutral conditions at the Boulder Atmospheric Observatory tower to quantify the effects of an abrupt 20- to 30-m increase in terrain located 3–5 km west of the tower. Results indicate ...

Brent M. Bowen

2000-05-01T23:59:59.000Z

317

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

318

Upstream Measurements of Wind Profiles with Doppler Lidar for Improved Wind Energy Integration  

DOE Green Energy (OSTI)

New upstream measurements of wind profiles over the altitude range of wind turbines will be produced using a scanning Doppler lidar. These long range high quality measurements will provide improved wind power forecasts for wind energy integration into the power grid. The main goal of the project is to develop the optimal Doppler lidar operating parameters and data processing algorithms for improved wind energy integration by enhancing the wind power forecasts in the 30 to 60 minute time frame, especially for the large wind power ramps. Currently, there is very little upstream data at large wind farms, especially accurate wind profiles over the full height of the turbine blades. The potential of scanning Doppler lidar will be determined by rigorous computer modeling and evaluation of actual Doppler lidar data from the WindTracer system produced by Lockheed Martin Coherent Technologies, Inc. of Louisville, Colorado. Various data products will be investigated for input into numerical weather prediction models and statistically based nowcasting algorithms. Successful implementation of the proposed research will provide the required information for a full cost benefit analysis of the improved forecasts of wind power for energy integration as well as the added benefit of high quality wind and turbulence information for optimal control of the wind turbines at large wind farms.

Rodney Frehlich

2012-10-30T23:59:59.000Z

319

Passively cooled direct drive wind turbine  

SciTech Connect

A wind turbine is provided that passively cools an electrical generator. The wind turbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Costin, Daniel P. (Chelsea, VT)

2008-03-18T23:59:59.000Z

320

Wind Energy  

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

FUPWG Meeting FUPWG Meeting NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC Robi Robichaud November 18, 2009 Topics Introduction Review of the Current Wind Market Drivers for Wind Development Siting g Issues Wind Resource Assessment Wind Characteristics Wind Power Potential Basic Wind Turbine Theory Basic Wind Turbine Theory Types of Wind Turbines Facts About Wind Siting Facts About Wind Siting Wind Performance 1. United States: MW 1 9 8 2 1 9 8 3 1 9 8 4 1 9 8 5 1 9 8 6 1 9 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 Current Status of the Wind Industry Total Global Installed Wind Capacity Total Global Installed Wind Capacity Total Global Installed Wind Capacity

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


321

NREL Develops New Controls that Proactively Adapt to the Wind (Fact Sheet)  

Science Conference Proceedings (OSTI)

Until now, wind turbine controls that reduce the impacts of wind gusts and turbulence were always reactive -- responding to the wind rather than anticipating it. But with today's laser-based sensors that measure wind speed ahead of the turbine, researchers at the National Renewable Energy Laboratory (NREL) and their industry partners are developing more intelligent controls. The world's first field tests of these controls are currently underway at the National Wind Technology Center (NWTC) at NREL, with plans for future commercialization.

Not Available

2012-10-01T23:59:59.000Z

322

NREL Develops New Controls that Proactively Adapt to the Wind (Fact Sheet)  

Science Conference Proceedings (OSTI)

Until now, wind turbine controls that reduce the impacts of wind gusts and turbulence were always reactive-responding to the wind rather than anticipating it. But with today's laser-based sensors that measure wind speed ahead of the turbine, researchers at the National Renewable Energy Laboratory (NREL) and their industry partners are developing more intelligent controls. The world's first field tests of these controls are currently underway at the National Wind Technology Center (NWTC) at NREL, with plans for future commercialization.

Not Available

2012-11-01T23:59:59.000Z

323

Improvement Of The Wind Farm Model Flap For Offshore Applications  

E-Print Network (OSTI)

The wind farm program FLaP (Farm Layout Program), developed at the University of Oldenburg, has been extended to improve the description of wake development in offshore conditions, especially the low ambient turbulence and the effect of atmospheric stability. Model results have been compared with measurements from the Danish offshore wind farm Vindeby. Vertical wake profiles and mean turbulence intensities in the wake were compared for 32 scenarios of single, double and quintuple wake cases with different mean wind speed, turbulence intensity and atmospheric stability. It was found that within the measurement uncertainties the results of the wake model compares well with the measurements for the most important ambient conditions. The effect of the low turbulence intensity offshore on the wake development was modelled well. Deviations have been found when atmospheric stability deviates from near-neutral conditions. Especially for stable atmospheric conditions both the free flow model and the wake model do not give satisfying results.

Bernhard Lange; Hans-peter Waldl; Rebecca Barthelmie; Algert Gil Guerrero; Detlev Heinemann

2002-01-01T23:59:59.000Z

324

Determining Turbulent Kinetic Energy Dissipation from Batchelor Curve Fitting  

Science Conference Proceedings (OSTI)

An algorithm is presented for obtaining the rate of turbulent kinetic energy dissipation by fitting the theoretical Batchelor spectrum to the temperature gradient spectrum at high wavenumbers. The algorithm is relatively robust in selecting the ...

David A. Luketina; Jörg Imberger

2001-01-01T23:59:59.000Z

325

Experimental Signatures of Critically Balanced Turbulence in MAST  

E-Print Network (OSTI)

Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, ...

Ghim, Y.-c.

326

Northerly surface wind events over the eastern North Pacific Ocean : spatial distribution, seasonality, atmospheric circulation, and forcing  

E-Print Network (OSTI)

D. (2005), California Wind Resources, CEC publication # CEC-level inversions with surface wind and temperature at PointD. W. Stuart (1986), Mesoscale wind variability near Point

Taylor, Stephen V.

2006-01-01T23:59:59.000Z

327

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

328

A New Approach to an Accurate Wind Chill Factor  

Science Conference Proceedings (OSTI)

Winter weather often shows a severity marked by low dry-bulb temperature combined with high wind speed. The wind chill factor is now a standard meteorological term to express this severity. This factor, or more appropriately the wind chill ...

Maurice Bluestein; Jack Zecher

1999-09-01T23:59:59.000Z

329

Analytical Shear Statistics Based on Nocturnal Wind Profiles  

Science Conference Proceedings (OSTI)

For a number of periods since 1978, wind and temperature profile measurements have been taken at two radio masts of 300 m height located in northern Germany. From wind profiles obtained during nocturnal conditions, wind shear data were calculated ...

K-P. Wittich; J. Hartmann; R. Roth

1986-11-01T23:59:59.000Z

330

IMPROVEMENT OF THE WIND FARM MODEL FLAP FOR OFFSHORE APPLICATIONS Bernhard Lange(1), Hans-Peter Waldl(1)(2), Rebecca Barthelmie(3), Algert Gil Guerrero(1)(4), Detlev Heinemann(1)  

E-Print Network (OSTI)

Vindeby. Vertical wake profiles and mean turbulence intensities in the wake were compared for 32 scenarios. Additionally, an estimation of turbulence intensity in the wind farm is essential for the load assumptions used in the description of the ambient vertical wind speed profile, but most importantly it leads to a low and wind speed

331

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

332

NREL: Wind Research - Computer-Aided Engineering Tools  

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

Computer-Aided Engineering Tools Computer-Aided Engineering Tools Illustration of an offshore wind turbine on a barge with an illustration of how the moorings would work. A simulation of a 5-MW wind turbine on an offshore semi-submersible with catenary moorings. The National Wind Technology Center (NWTC) at NREL develops advanced computer-aided engineering (CAE) tools to support the wind and water power industries with state-of-the-art design and analysis capabilities. We have developed many software tools that produce realistic models that simulate the behavior of wind and water power technologies in complex environments-storm winds, waves offshore, earthquake loading, and extreme turbulence-and model the effects of turbulent inflow, unsteady aerodynamic forces, structural dynamics, drivetrain response, control

333

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

334

Density Spectrum in the Solar Wind Plasma  

E-Print Network (OSTI)

The density fluctuation spectrum in the solar wind reveals a Kolmogorov-like scaling with a spectral slope of -5/3 in wavenumber space. The energy transfer process in the magnetized solar wind, characterized typically by MHD turbulence, over extended length-scales remains an unresolved paradox of modern turbulence theories, raising the question of how a compressible magnetofluid exhibits a turbulent spectrum that is characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfv\\'enic, supersonic and strongly magnetized plasma fluid. It is shown that a Kolmogorov-like density spectrum can develop by plasma motions that are dominated by Alfv\\'enic cascades whereas compressive modes are dissipated.

Shaikh, Dastgeer

2009-01-01T23:59:59.000Z

335

doi:10.1088/0004-637X/702/2/1604 EMPIRICAL CONSTRAINTS ON PROTON AND ELECTRON HEATING IN THE FAST SOLAR WIND  

E-Print Network (OSTI)

We analyze measured proton and electron temperatures in the high-speed solar wind in order to calculate the separate rates of heat deposition for protons and electrons. When comparing with other regions of the heliosphere, the fast solar wind has the lowest density and the least frequent Coulomb collisions. This makes the fast wind an optimal testing ground for studies of collisionless kinetic processes associated with the dissipation of plasma turbulence. Data from the Helios and Ulysses plasma instruments were collected to determine mean radial trends in the temperatures and the electron heat conduction flux between 0.29 and 5.4 AU. The derived heating rates apply specifically for these mean plasma properties and not for the full range of measured values around the mean. We found that the protons receive about 60 % of the total plasma heating in the inner heliosphere, and that this fraction increases to approximately 80 % by the orbit of Jupiter. A major factor affecting the uncertainty in this fraction is the uncertainty in the measured radial gradient of the electron heat conduction flux. The empirically derived partitioning of heat between protons and electrons is in rough agreement with theoretical predictions from a model of linear Vlasov wave damping. For a modeled power spectrum consisting only of Alfvénic fluctuations, the best agreement was found for a distribution of wavenumber vectors that evolves toward isotropy as distance increases. Key words: hydrodynamics – MHD – plasmas – solar windturbulence – waves Online-only material: color figures 1.

Steven R. Cranmer; William H. Matthaeus; Benjamin A. Breech; Justin C. Kasper

2009-01-01T23:59:59.000Z

336

SPECTRUM OF KINETIC-ALFVEN TURBULENCE  

Science Conference Proceedings (OSTI)

A numerical study of strong kinetic-Alfven turbulence at scales smaller than the ion gyroscale is presented, and a phenomenological model is proposed that argues that magnetic and density fluctuations are concentrated mostly in two-dimensional structures, which leads to their Fourier energy spectra E(k ){proportional_to}k {sup -8/3} , where k is the wavevector component normal to the strong background magnetic field. The results may provide an explanation for recent observations of magnetic and density fluctuations in the solar wind at sub-proton scales.

Boldyrev, Stanislav; Perez, Jean Carlos [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

2012-10-20T23:59:59.000Z

337

A COOLING SYSTEM FOR BUIDINGS USING WIND ENERGY  

E-Print Network (OSTI)

A COOLING SYSTEM FOR BUIDINGS USING WIND ENERGY Hamid Daiyan Islamic Azad University - Semnan in dray land, and only uses wind energy for conditioning. It technologies date back over 1000 years. Wind system, Wind energy, Temperature Fig.1 Wind tower of Doulat-Abad garden of Yazd with it's altitude is 33

338

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

339

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

340

The Effects of the Variations In Sea Surface Temperature and Atmospheric Stability in the Estimation of Average Wind Speed by SEASAT-SASS  

Science Conference Proceedings (OSTI)

Wind speeds from the scatterometer (SASS) on the ocean observing satellite SEASAT averaged over 2° latitude by 2° longitude and a 92-day period are compared with wind speeds from ship reports in the western North Atlantic and the eastern North ...

W. Timothy Liu

1984-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Boundary Plasma Turbulence Simulations for Tokamaks  

SciTech Connect

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

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

2008-05-15T23:59:59.000Z

342

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

343

EIA: Wind  

U.S. Energy Information Administration (EIA)

Technical information and data on the wind energy industry from the U.S. Energy Information Administration (EIA).

344

Wind loading on solar collectors  

DOE Green Energy (OSTI)

The present design methodology for the determination of wind loading on the various solar collectors has been reviewed and assessed. The total force coefficients of flat plates of aspect ratios 1.0 and 3.0, respectively, at various angles of attack obtained by using the guidelines of the ANSI A58.1-1982, have been compared with those obtained by using the methodology of the ASCE Task Committee, 1961, and the experimental results of the full-scale test of heliostats by Peglow. The turbulent energy spectra, currently employed in the building code, are compared with those of Kaimal et al., Lumley, and Ponofsky for wind velocities of 20.0 m/s and 40.24 m/s at an elevation of 9.15 m. The longitudinal spectra of the building code overestimates the Kaimal spectra in the frequency range of 0.007 Hz to 0.08 Hz and underestimates beyond the frequency of 0.08 Hz. The peak angles of attack, on the heliostat, stowed in horizontal position, due to turbulent vertical and lateral components of wind velocity, have been estimated by using Daniel's methodology for three wind velocities and compared with the value suggested by the code. The experimental results of a simple test in the laboratory indicate the feasibility of decreasing the drag forces of the flat plate by reducing the solidity ratio.

Bhaduri, S.; Murphy, L.M.

1985-06-01T23:59:59.000Z

345

Reducing Turbulent Transport in Toroidal Configurations via Shaping  

Science Conference Proceedings (OSTI)

Recent progress in reducing turbulent transport in stellarators and tokamaks by 3D shaping using a stellarator optimization code in conjunction with a gyrokinetic code is presented. The original applications of the method focussed on ion temperature gradient transport in a quasi-axisymmetric stellarator design. Here, an examination of both other turbulence channels and other starting configurations is initiated. It is found that the designs evolved for transport from ion temperature gradient turbulence also display reduced transport from other transport channels whose modes are also stabilized by improved curvature, such as electron temperature gradient and ballooning modes. The optimizer is also applied to evolving from a tokamak, finding appreciable turbulence reduction for these devices as well. From these studies, improved understanding is obtained of why the deformations found by the optimizer are beneficial, and these deformations are related to earlier theoretical work in both stellarators and tokamaks.

H.E. Mynick, N. Pomphrey and P. Xanthopoulos

2011-04-20T23:59:59.000Z

346

Passive Acoustic Detection of Wind Turbine In-Flow Conditions for Active Control and Optimization  

DOE Green Energy (OSTI)

Wind is a significant source of energy; however, the human capability to produce electrical energy still has many hurdles to overcome. One of these is the unpredictability of the winds in the atmospheric boundary layer (ABL). The ABL is highly turbulent in both stable and unstable conditions (based on the vertical temperature profile) and the resulting fluctuations can have a dramatic impact on wind turbine operation. Any method by which these fluctuations could be observed, estimated, or predicted could provide a benefit to the wind energy industry as a whole. Based on the fundamental coupling of velocity fluctuations to pressure fluctuations in the nearly incompressible flow in the ABL, This work hypothesizes that a ground-based array of infrasonic pressure transducers could be employed to estimate the vertical wind profile over a height relevant for wind turbines. To analyze this hypothesis, experiments and field deployments were conducted. Wind tunnel experiments were performed for a thick turbulent boundary layer over a neutral or heated surface. Surface pressure and velocity probe measurements were acquired simultaneously. Two field deployments yielded surface pressure data from a 49 element array. The second deployment at the Reese Technology Center in Lubbock, TX, also included data from a smaller aperture, 96-element array and a 200-meter tall meteorological tower. Analysis of the data successfully demonstrated the ability to estimate the vertical velocity profile using coherence data from the pressure array. Also, dynamical systems analysis methods were successful in identifying and tracking a gust type event. In addition to the passive acoustic profiling method, this program also investigated a rapid response Doppler SODAR system, the optimization of wind turbine blades for enhanced power with reduced aeroacoustic noise production, and the implementation of a wireless health monitoring system for the wind turbine blades. Each of these other objectives was met successfully. The use of phase unwrapping applied to SODAR data was found to yield reasonable results for per-pulse measurements. A health monitoring system design analysis was able to demonstrate the ability to use a very small number of sensors to monitor blade health based on the blade's overall structural modes. Most notable was the development of a multi-objective optimization methodology that successfully yielded an aerodynamic blade design that produces greater power output with reduced aerodynamic loading noise. This optimization method could be significant for future design work.

Murray, Nathan E.

2012-03-12T23:59:59.000Z

347

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

348

Wind Blog  

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

wind-blog Office of Energy Efficiency & Renewable wind-blog Office of Energy Efficiency & Renewable Energy Forrestal Building 1000 Independence Avenue, SW Washington, DC 20585 en Two Facilities, One Goal: Advancing America's Wind Industry http://energy.gov/eere/articles/two-facilities-one-goal-advancing-america-s-wind-industry wind-industry" class="title-link">Two Facilities, One Goal: Advancing America's Wind Industry

349

Ignition of hydrogen/air mixing layer in turbulent flows  

DOE Green Energy (OSTI)

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

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

1998-03-01T23:59:59.000Z

350

Dependence of Wind Turbine Curves on Atmospheric Stability Regimes - An Analysis of a West Coast North American Tall Wind Farm  

DOE Green Energy (OSTI)

Tall wind turbines, with hub heights at 80 m or above, can extract large amounts of energy from the atmosphere because they are likely to encounter higher wind speeds, but they face challenges given the complex nature of wind flow in the boundary layer. Depending on whether the boundary layer is stable, convective or neutral, mean wind speed (U) and turbulence ({sigma}{sub U}) may vary greatly across the tall turbine swept area (40 m to 120 m). This variation can cause a single turbine to produce difference amounts of power during time periods of identical hub height wind speeds. The study examines the influence that atmospheric mixing or stability has on power output at a West Coast North American wind farm. They first examine the accuracy and applicability of two, relatively simple stability parameters, the wind shear-exponent, {alpha}, and the turbulence intensity, I{sub u}, against the physically-based, Obukhov length, L, to describe the wind speed and turbulence profiles in the rotor area. In general, the on-site stability parameters {alpha} and I{sub u} are in high agreement with the off-site, L stability scale parameter. Next, they divide the measurement period into five stability classes (strongly stable, stable, neutral, convective, and strongly convective) to discern stability-effects on power output. When only the mean wind speed profile is taken into account, the dependency of power output on boundary layer stability is only subtly apparent. When turbulence intensity I{sub u} is considered, the power generated for a given wind speed is twenty percent higher during strongly stable conditions than during strongly convective conditions as observed in the spring and summer seasons at this North American wind farm.

Wharton, S; Lundquist, J K; Sharp, J; Zulauf, M

2009-08-24T23:59:59.000Z

351

Simulation of ENSO-Related Surface Winds in the Tropical Pacific by an Atmospheric General Circulation Model Forced by Observed Sea Surface Temperatures  

Science Conference Proceedings (OSTI)

The authors present the simulation of the tropical Pacific surface wind variability by a low-resolution (R15 horizontal resolution and 18 vertical levels) version of the Center for Ocean-Land-Atmosphere Interactions, Maryland, general circulation ...

B. N. Goswami; V. Krishnamurthy; N. H. Saji

1995-06-01T23:59:59.000Z

352

Interdecadal Sea Surface Temperature Variability in the Equatorial Pacific Ocean. Part II: The Role of Equatorial/Off-Equatorial Wind Stresses in a Hybrid Coupled Model  

Science Conference Proceedings (OSTI)

Many modeling studies have been carried out to investigate the role of oceanic Rossby waves linking the off-equatorial and equatorial Pacific Ocean. Although the equatorial ocean response to off-equatorial wind stress forcing alone tends to be ...

Shayne McGregor; Neil J. Holbrook; Scott B. Power

2008-09-01T23:59:59.000Z

353

Self Consistent Models of the Solar Wind  

E-Print Network (OSTI)

The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of much debate. This paper summarizes some of the essential ingredients of realistic and self-consistent models of solar wind acceleration. It also outlines the major issues in the recent debate over what physical processes dominate the mass, momentum, and energy balance in the accelerating wind. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent models that assume the energy comes from Alfven waves that are partially reflected, and then dissipated by magnetohydrodynamic turbulence, have been found to reproduce many of the observed features of the solar wind. This paper discusses results from these models, including detailed comparisons with measured plasma properties as a function of solar wind speed. Some suggestions are also given for future work that could answer the many remain...

Cranmer, Steven R

2010-01-01T23:59:59.000Z

354

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

Science Conference Proceedings (OSTI)

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

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

2011-02-15T23:59:59.000Z

355

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

356

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 (TEMs). 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 wavenumber 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 ExB 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.

Wang, W. X.; Hahm, T. S.; Ethier, S.; Rewoldt, G.; Tang, W. M. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States); Diamond, P. H. [University of California, San Diego, La Jolla, California 92093 (United States)

2010-07-15T23:59:59.000Z

357

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

358

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

359

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

360

Energy Basics: Wind Turbines  

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

Energy Basics Renewable Energy Printable Version Share this resource Biomass Geothermal Hydrogen Hydropower Ocean Solar Wind Wind Turbines Wind Resources Wind Turbines...

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Standards for Municipal Small Wind Regulations and Small Wind...  

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

Standards for Municipal Small Wind Regulations and Small Wind Model Wind Ordinance Standards for Municipal Small Wind Regulations and Small Wind Model Wind Ordinance Eligibility...

362

Tropical Cyclone Wind Retrievals from the Advanced Microwave Sounding Unit: Application to Surface Wind Analysis  

Science Conference Proceedings (OSTI)

Horizontal winds at 850 hPa from tropical cyclones retrieved using the nonlinear balance equation, where the mass field was determined from Advanced Microwave Sounding Unit (AMSU) temperature soundings, are compared with the surface wind fields ...

Kotaro Bessho; Mark DeMaria; John A. Knaff

2006-03-01T23:59:59.000Z

363

Wind Tunnel Aeroacoustic Tests of Six Airfoils for Use on Small Wind Turbines: Preprint  

DOE Green Energy (OSTI)

Aeroacoustic tests of seven airfoils were performed in an open jet anechoic wind tunnel. Six of the airfoils are candidates for use on small wind turbines operating at low Reynolds number. One airfoil was tested for comparison to benchmark data. Tests were conducted with and without boundary layer tripping. In some cases a turbulence grid was placed upstream in the test section to investigate inflow turbulence noise. An array of 48 microphones was used to locate noise sources and separate airfoil noise from extraneous tunnel noise. Trailing edge noise was dominant for all airfoils in clean tunnel flow. With the boundary layer untripped, several airfoils exhibited pure tones that disappeared after proper tripping was applied. In the presence of inflow turbulence, leading edge noise was dominant for all airfoils.

Migliore, P.; Oerlemans, S.

2003-12-01T23:59:59.000Z

364

A Phenomenological Model for Wind Speed and Shear Stress Profiles in Vegetation Cover Layers  

Science Conference Proceedings (OSTI)

A phenomenological model for the mean wind speed and Reynolds shear stress profiles with height in a vegetation cover layer is derived from forms suggested by truncation of the equations of turbulent fluid motion at second order in fluctuating ...

F. A. Albini

1981-11-01T23:59:59.000Z

365

Use of a Large Crane for Wind and Tracer Profiles in an Urban Setting  

Science Conference Proceedings (OSTI)

Although measured vertical profiles of wind, turbulence, and tracer concentrations are critical for understanding the urban boundary layer, it is problematic to field a sounding system or a tall structure to support anemometers in a densely ...

Frank J. Gouveia; Martin J. Leach; Joseph H. Shinn; William E. Ralph

2007-10-01T23:59:59.000Z

366

The Variational Assimilation Method for the Retrieval of Humidity Profiles with the Wind-Profiling Radar  

Science Conference Proceedings (OSTI)

Recently, a humidity estimation technique was developed by using the turbulence echo characteristics detected with a wind-profiling radar. This study is concerned with improvement of the retrieval algorithm for delineating a humidity profile from ...

Jun-ichi Furumoto; Shingo Imura; Toshitaka Tsuda; Hiromu Seko; Tadashi Tsuyuki; Kazuo Saito

2007-09-01T23:59:59.000Z

367

First- and Second-Order Closure Models for Wind in a Plant Canopy  

Science Conference Proceedings (OSTI)

Katul and Chang recently compared the performance of two second-order closure models with observations of wind and turbulence in the Duke Forest canopy, noting that such models “alleviate some of the theoretical objections to first-order closure.”...

J. D. Jean-Paul Pinard; John D. Wilson

2001-10-01T23:59:59.000Z

368

E – ? model of spray-laden near-sea atmospheric layer in high wind conditions  

Science Conference Proceedings (OSTI)

In-depth understanding and accurate modelling of the interaction between ocean spray and a turbulent flow under high-wind conditions is essential for improving intensity forecasts of hurricanes and severe storms. Here we consider the E – ? closure ...

Yevgenii Rastigejev; Sergey A. Suslov

369

Enhancement of Crosswind Pollutant Dispersion by Steadily Veering Winds in Sea Breezes  

Science Conference Proceedings (OSTI)

An estimate is given of the relative importance of wind veering and turbulent diffusion in the mean horizontal spread of pollutant plumes in the atmosphere. Documented veering rates in sea breezes are used to illustrate the effect, and it is ...

D. G. Steyn; M. Segal

1990-05-01T23:59:59.000Z

370

Uncertainty of Boundary Layer Heat Budgets Computed from Wind Profiler—RASS Networks  

Science Conference Proceedings (OSTI)

Uncertainties in the evaluation of the atmospheric heat budget, in which the turbulent heat flux divergence term is calculated as a residual, are investigated for a triangular array of 915-MHz wind profilers—radio acoustic sounding systems (RASS) ...

Markus Furger; C. David Whiteman; James M. Wilczak

1995-03-01T23:59:59.000Z

371

Effects of Wind Field Inhomogeneities on Doppler Beam Swinging Revealed by an Imaging Radar  

Science Conference Proceedings (OSTI)

In this work, the accuracy of the Doppler beam-swinging (DBS) technique for wind measurements is studied using an imaging radar—the turbulent eddy profiler (TEP) developed by the University of Massachusetts, with data collected in summer 2003. ...

B. L. Cheong; R. D. Palmer; T-Y. Yu; K-F. Yang; M. W. Hoffman; S. J. Frasier; F. J. Lopez-Dekker

2008-08-01T23:59:59.000Z

372

Wind Turbines  

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

Although all wind turbines operate on similar principles, several varieties are in use today. These include horizontal axis turbines and vertical axis turbines.

373

NREL: Wind Research - Large Wind Turbine Research  

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

Wind Research Search More Search Options Site Map Printable Version Large Wind Turbine Research NREL's utility scale wind system research addresses performance and...

374

Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD  

DOE Green Energy (OSTI)

An investigation was conducted into the capabilities and accuracy of a representative computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data. This work highlights two areas in CFD that require further investigation and development in order to enable accurate numerical simulations of flow about current generation wind-turbine airfoils: transition prediction and turbulence modeling. The results show that the laminar-to turbulent transition point must be modeled correctly to get accurate simulations for attached flow. Calculations also show that the standard turbulence model used in most commercial CFD codes, the k-e model, is not appropriate at angles of attack with flow separation. 14 refs., 28 figs., 4 tabs.

Wolfe, W.P. [Sandia National Labs., Albuquerque, NM (United States); Ochs, S.S. [Iowa State Univ., Ames, IA (United States). Aerospace Engineering Dept.

1997-09-01T23:59:59.000Z

375

Risø–I–1206(EN) Wind Power Meteorology  

E-Print Network (OSTI)

Abstract Wind power meteorology has evolved as an applied science, firmly founded on boundary-layer meteorology, but with strong links to climatology and geography. It concerns itself with three main areas: siting of wind turbines, regional wind resource assessment, and short-term prediction of the wind resource. The history, status and perspectives of wind power meteorology are presented, with emphasis on physical considerations and on its practical application. Following a global view of the wind resource, the elements of boundary layer meteorology which are most important for wind energy are reviewed: wind profiles and shear, turbulence and gust, and extreme winds. The data used in wind power meteorology stem mainly from three sources: onsite wind measurements, the synoptic networks, and the re-analysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed description of the topography of the terrain – with respect to the roughness of the surface, near-by obstacles, and orographical features. Finally, the meteorological models used for estimation and prediction of the wind are described; their classification,

Erik L. Petersen; Niels G. Mortensen; Lars L; Jørgen Højstrup; Helmut P. Frank

1997-01-01T23:59:59.000Z

376

Wind Powering America: Wind Events  

Wind Powering America (EERE)

calendar.asp Lists upcoming wind calendar.asp Lists upcoming wind power-related events. en-us julie.jones@nrel.gov (Julie Jones) http://www.windpoweringamerica.gov/images/wpa_logo_sm.jpg Wind Powering America: Wind Events http://www.windpoweringamerica.gov/calendar.asp Pennsylvania Wind for Schools Educator Workshop https://www.regonline.com/builder/site/Default.aspx?EventID=1352684 http://www.windpoweringamerica.gov/filter_detail.asp?itemid=4068 Wed, 4 Dec 2013 00:00:00 MST 2014 Joint Action Workshop http://www.windpoweringamerica.gov/filter_detail.asp?itemid=3996 http://www.windpoweringamerica.gov/filter_detail.asp?itemid=3996 Mon, 21 Oct 2013 00:00:00 MST AWEA Wind Project Operations and Maintenance and Safety Seminar http://www.windpoweringamerica.gov/filter_detail.asp?itemid=4009 http://www.windpoweringamerica.gov/filter_detail.asp?itemid=4009 Mon, 21

377

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

378

Beyond the Betz Theory - Blockage, Wake Mixing and Turbulence  

E-Print Network (OSTI)

Recent analytical models concerning the limiting efficiency of marine hydrokinetic (MHK) devices are reviewed with an emphasis on the significance of blockages (of local as well as global flow passages) and wake mixing. Also discussed is the efficiency of power generation from fully developed turbulent open channel flows. These issues are primarily concerned with the design/optimization of tidal turbine arrays; however, some of them are relevant to wind turbines as well.

Nishino, Takafumi

2013-01-01T23:59:59.000Z

379

Analysis of mixing layer heights inferred from radiosonde, wind profiler, airborne lidar, airborne microwave temperature profiler, and in-situ aircraft data during the Texas 2000 air quality study in Houston, TX  

E-Print Network (OSTI)

The mixing layer (ML) heights inferred from radiosondes, wind profilers, airborne lidar, airborne microwave temperature profiler (MTP), and in-situ aircraft data were compared during the Texas 2000 Air Quality Study in the Houston area. The comparisons and resulting good agreement between the separate instruments allowed for the spatial and temporal evolution of the ML height distribution to be determined across the Houston area on September 1, 2000. A benchmark method was created for determining ML heights from radiosonde data. The ML heights determined using this method were compared to ML heights determined using wind profiler data. The airborne lidar and MTP heights were also compared to the wind profiler heights. This was the first time the MTP was used for estimating ML heights. Because of this, the MTP heights were also compared to the ML heights determined by in-situ aircraft data. There was good agreement between the ML estimates when the instruments were co-located. The comparisons between the benchmark method and the wind profilers were independent of the quality of the profiler heights. The statistics for lidar and the wind profilers were better for the inland profiler comparisons. Even so, the results for coastal profilers were similar to the other comparisons. The results between the MTP and the wind profilers were comparable with the results found between the other instruments, and better, in that the statistics were similar for the both the inland and coastal profilers. The results between the MTP and in-situ aircraft data provided additional support for the use of MTP for determining ML heights. The combination of the inland and coastal wind profilers with the airborne instruments provided adequate information for the spatial and temporal evolution of the ML height to be determined across the Houston area on September 1, 2000. By analyzing the ML height distribution, major features were evident. These features included the shallow ML heights associated with the marine air from Galveston Bay and the Gulf of Mexico, and the sharp gradient of increasing ML heights north of Houston associated with the variation in the inversion depth found on this day.

Smith, Christina Lynn

2003-05-01T23:59:59.000Z

380

Extreme Winds and Wind Effects on Structures  

Science Conference Proceedings (OSTI)

Extreme Winds and Wind Effects on Structures. Description/Summary: The Building and Fire Research Laboratory has an ...

2010-10-04T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

Origins of Aircraft-Damaging Clear-Air Turbulence during the 9 December 1992 Colorado Downslope Windstorm: Numerical Simulations and Comparison with Observations  

Science Conference Proceedings (OSTI)

Results from numerical simulations of the Colorado Front Range downslope windstorm of 9 December 1992 are presented. Although this case was not characterized by severe surface winds, the event caused extreme clear-air turbulence (CAT) aloft, as ...

Terry L. Clark; William D. Hall; Robert M. Kerr; Don Middleton; Larry Radke; F. Martin Ralph; Paul J. Neiman; David Levinson

2000-04-01T23:59:59.000Z

382

Wind Energy Leasing Handbook  

E-Print Network (OSTI)

Wind Energy Leasing Handbook Wind Energy Leasing Handbook E-1033 Oklahoma Cooperative Extension?..................................................................................................................... 31 What do wind developers consider in locating wind energy projects?............................................................................................ 37 How do companies and individuals invest in wind energy projects?....................................................................

Balasundaram, Balabhaskar "Baski"

383

Wind Powering America: New England Wind Forum  

Wind Powering America (EERE)

About the New England Wind Forum About the New England Wind Forum New England Wind Energy Education Project Historic Wind Development in New England State Activities Projects in New England Building Wind Energy in New England Wind Resource Wind Power Technology Economics Markets Siting Policy Technical Challenges Issues Small Wind Large Wind Newsletter Perspectives Events Quick Links to States CT MA ME NH RI VT Bookmark and Share The New England Wind Forum was conceived in 2005 as a platform to provide a single, comprehensive and objective source of up-to-date, Web-based information on a broad array of wind-energy-related issues pertaining to New England. The New England Wind Forum provides information to wind energy stakeholders through Web site features, periodic newsletters, and outreach activities. The New England Wind Forum covers the most frequently discussed wind energy topics.

384

Mesoscale and Large-Eddy Simulations for Wind Energy  

Science Conference Proceedings (OSTI)

Operational wind power forecasting, turbine micrositing, and turbine design require high-resolution simulations of atmospheric flow over complex terrain. The use of both Reynolds-Averaged Navier Stokes (RANS) and large-eddy (LES) simulations is explored for wind energy applications using the Weather Research and Forecasting (WRF) model. To adequately resolve terrain and turbulence in the atmospheric boundary layer, grid nesting is used to refine the grid from mesoscale to finer scales. This paper examines the performance of the grid nesting configuration, turbulence closures, and resolution (up to as fine as 100 m horizontal spacing) for simulations of synoptically and locally driven wind ramping events at a West Coast North American wind farm. Interestingly, little improvement is found when using higher resolution simulations or better resolved turbulence closures in comparison to observation data available for this particular site. This is true for week-long simulations as well, where finer resolution runs show only small changes in the distribution of wind speeds or turbulence intensities. It appears that the relatively simple topography of this site is adequately resolved by all model grids (even as coarse as 2.7 km) so that all resolutions are able to model the physics at similar accuracy. The accuracy of the results is shown in this paper to be more dependent on the parameterization of the land-surface characteristics such as soil moisture rather than on grid resolution.

Marjanovic, N

2011-02-22T23:59:59.000Z

385

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

386

Chapter 14: Wind Turbine Control Systems  

DOE Green Energy (OSTI)

Wind turbines are complex, nonlinear, dynamic systems forced by gravity, stochastic wind disturbances, and gravitational, centrifugal, and gyroscopic loads. The aerodynamic behavior of wind turbines is nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated three-dimensional turbulent wind inflow field that drives fatigue loading. Wind turbine modeling is also complex and challenging. Accurate models must contain many degrees of freedom (DOF) to capture the most important dynamic effects. The rotation of the rotor adds complexity to the dynamics modeling. Designs of control algorithms for wind turbines must account for these complexities. Algorithms must capture the most important turbine dynamics without being too complex and unwieldy. Off-the-shelf commercial soft ware is seldom adequate for wind turbine dynamics modeling. Instead, specialized dynamic simulation codes are usually required to model all the important nonlinear effects. As illustrated in Figure 14-1, a wind turbine control system consists of sensors, actuators and a system that ties these elements together. A hardware or software system processes input signals from the sensors and generates output signals for actuators. The main goal of the controller is to modify the operating states of the turbine to maintain safe turbine operation, maximize power, mitigate damaging fatigue loads, and detect fault conditions. A supervisory control system starts and stops the machine, yaws the turbine when there is a significant yaw misalignment, detects fault conditions, and performs emergency shut-downs. Other parts of the controller are intended to maximize power and reduce loads during normal turbine operation.

Wright, A. D.

2009-01-01T23:59:59.000Z

387

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

388

Empirical Constraints on Proton and Electron Heating in the Fast Solar Wind  

E-Print Network (OSTI)

We analyze measured proton and electron temperatures in the high-speed solar wind in order to calculate the separate rates of heat deposition for protons and electrons. When comparing with other regions of the heliosphere, the fast solar wind has the lowest density and the least frequent Coulomb collisions. This makes the fast wind an optimal testing ground for studies of collisionless kinetic processes associated with the dissipation of plasma turbulence. Data from the Helios and Ulysses plasma instruments were collected to determine mean radial trends in the temperatures and the electron heat conduction flux between 0.29 and 5.4 AU. The derived heating rates apply specifically for these mean plasma properties and not for the full range of measured values around the mean. We found that the protons receive about 60% of the total plasma heating in the inner heliosphere, and that this fraction increases to approximately 80% by the orbit of Jupiter. A major factor affecting the uncertainty in this fraction is th...

Cranmer, Steven R; Breech, Benjamin A; Kasper, Justin C

2009-01-01T23:59:59.000Z

389

High Horizontal and Vertical Resolution Limited-Area Model: Near-Surface and Wind Energy Forecast Applications  

Science Conference Proceedings (OSTI)

As harvesting of wind energy grows, so does the need for improved forecasts from the surface to the top of wind turbines. To improve mesoscale forecasts of wind, temperature, and dewpoint temperature in this layer, two different approaches are ...

Natacha B. Bernier; Stéphane Bélair

2012-06-01T23:59:59.000Z

390

Wind News  

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

news Office of Energy Efficiency & Renewable news Office of Energy Efficiency & Renewable Energy Forrestal Building 1000 Independence Avenue, SW Washington, DC 20585 en New Report Shows Trend Toward Larger Offshore Wind Systems, with 11 Advanced Stage Projects Proposed in U.S. Waters http://energy.gov/eere/articles/new-report-shows-trend-toward-larger-offshore-wind-systems-11-advanced-stage-projects wind-systems-11-advanced-stage-projects" class="title-link">New Report Shows Trend Toward Larger Offshore Wind Systems, with 11 Advanced Stage Projects Proposed in U.S. Waters

391

Wind Power  

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

Power As the accompanying map of New Mexico shows, the best wind power generation potential near WIPP is along the Delaware Mountain ridge line of the southern Guadalupe Mountains,...

392

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

393

Dynamic stall on wind turbine blades  

DOE Green Energy (OSTI)

Dynamic loads must be predicted accurately in order to estimate the fatigue life of wind turbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis wind turbine (HAWTs). This report illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operating conditions. Lift, drag, and pitching moment coefficients during dynamics stall are discussed. Resulting dynamic loads are presented, and the effects of dynamic stall on yaw loads are demonstrated using a yaw loads dynamic analysis (YAWDYN). 12 refs., 22 figs., 1 tab.

Butterfield, C.P.; Simms, D.; Scott, G. [National Renewable Energy Lab., Golden, CO (United States)] [National Renewable Energy Lab., Golden, CO (United States); Hansen, A.C. [Utah Univ., Salt Lake City, UT (United States)] [Utah Univ., Salt Lake City, UT (United States)

1991-12-01T23:59:59.000Z

394

Using time-frequency and wavelet analysis to assess turbulence/rotor interactions  

DOE Green Energy (OSTI)

Large loading events on wind turbine rotor blades are often associated with transient bursts of coherent turbulent energy in the turbine inflow. These coherent turbulent structures are identified as peaks in the three-dimensional, instantaneous, turbulent shearing stress field. Such organized inflow structures and the accompanying rotor aeroelastic responses typically have time scales of only a few seconds and therefore do not lend themselves for analysis by conventional Fourier spectral techniques. Time-frequency analysis (and wavelet analysis in particular) offers the ability to more closely study the spectral decomposition of short period events such as the interaction of coherent turbulence with a moving rotor blade. In this paper, the authors discuss the initial progress in the application of time-frequency analysis techniques to the decomposition and interpretation of turbulence/rotor interaction. The authors discuss the results of applying both the continuous and discrete wavelet transforms for their application. Several examples are given of the techniques applied to both observed turbulence and turbine responses and those generated using numerical simulations. They found that the presence of coherent turbulent structures, as revealed by the inflow Reynolds stress field, is a major contributor to large load excursions. These bursts of coherent turbulent energy induce a broadband aeroelastic response in the turbine rotor as it passes through them.

Kelley, N.D.; Osgood, R.M.; Bialasiewicz, J.T.; Jakubowski, A.

2000-01-05T23:59:59.000Z

395

Aleutian Pribilof Islands Wind Energy Feasibility Study  

DOE Green Energy (OSTI)

Under this project, the Aleutian Pribilof Islands Association (APIA) conducted wind feasibility studies for Adak, False Pass, Nikolski, Sand Point and St. George. The DOE funds were also be used to continue APIA's role as project coordinator, to expand the communication network quality between all participants and with other wind interest groups in the state and to provide continued education and training opportunities for regional participants. This DOE project began 09/01/2005. We completed the economic and technical feasibility studies for Adak. These were funded by the Alaska Energy Authority. Both wind and hydro appear to be viable renewable energy options for Adak. In False Pass the wind resource is generally good but the site has high turbulence. This would require special care with turbine selection and operations. False Pass may be more suitable for a tidal project. APIA is funded to complete a False Pass tidal feasibility study in 2012. Nikolski has superb potential for wind power development with Class 7 wind power density, moderate wind shear, bi-directional winds and low turbulence. APIA secured nearly $1M from the United States Department of Agriculture Rural Utilities Service Assistance to Rural Communities with Extremely High Energy Costs to install a 65kW wind turbine. The measured average power density and wind speed at Sand Point measured at 20m (66ft), are 424 W/m2 and 6.7 m/s (14.9 mph) respectively. Two 500kW Vestas turbines were installed and when fully integrated in 2012 are expected to provide a cost effective and clean source of electricity, reduce overall diesel fuel consumption estimated at 130,000 gallons/year and decrease air emissions associated with the consumption of diesel fuel. St. George Island has a Class 7 wind resource, which is superior for wind power development. The current strategy, led by Alaska Energy Authority, is to upgrade the St. George electrical distribution system and power plant. Avian studies in Nikolski and Sand Point have allowed for proper wind turbine siting without killing birds, especially endangered species and bald eagles. APIA continues coordinating and looking for funding opportunities for regional renewable energy projects. An important goal for APIA has been, and will continue to be, to involve community members with renewable energy projects and energy conservation efforts.

Bruce A. Wright

2012-03-27T23:59:59.000Z

396

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

397

ELECTRONIC BIVANE WIND DIRECTION INDICATOR  

DOE Patents (OSTI)

An apparatus is described for determining and recording three dimensional wind vectors. The apparatus comprises a rotatably mounted azimuthal wind component sensing head and an elevational wind component sensing head mounted to the azimuthal head and adapted to rotate therewith in the azimuthal plane and independently in the elevational plane. A heat source and thermocouples disposed thereabout are mounted within each of the sensing heads, the thermocouples providing electrical signals responsive to the temperature differential created by the passage of air through the sensing tuhes. The thermocouple signals are applied to drive mechanisms which position the sensing heads to a null wind position. Recording means are provided responsive to positional data from the drive mechanisms which are a measurement of the three dimensional wind vectors.

Moses, H.

1961-05-01T23:59:59.000Z

398

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

399

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

400

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

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

402

The Probability Distribution of Sea Surface Wind Speeds: Effects of Variable Surface Stratification and Boundary Layer Thickness  

Science Conference Proceedings (OSTI)

Air–sea exchanges of momentum, energy, and material substances of fundamental importance to the variability of the climate system are mediated by the character of the turbulence in the atmospheric and oceanic boundary layers. Sea surface winds ...

Adam Hugh Monahan

2010-10-01T23:59:59.000Z

403

New England Wind Forum: Wind Power Technology  

Wind Powering America (EERE)

Wind Power Technology Wind Power Technology Modern wind turbines have become sophisticated power plants while the concept of converting wind energy to electrical energy remains quite simple. Follow these links to learn more about the science behind wind turbine technology. Wind Power Animation An image of a scene from the wind power animation. The animation shows how moving air rotates a wind turbine's blades and describes how the internal components work to produce electricity. It shows small and large wind turbines and the differences between how they are used, as stand alone or connected to the utility grid. How Wind Turbines Work Learn how wind turbines make electricity; what are the types, sizes, and applications of wind turbines; and see an illustration of the components inside a wind turbine.

404

NREL: Wind Research - Wind Resource Assessment  

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

Wind Resource Assessment Wind Resource Assessment A map of the United States is color-coded to indicate the high winds at 80 meters. This map shows the wind resource at 80 meters for both land-based and offshore wind resources in the United States. Correct estimation of the energy available in the wind can make or break the economics of wind plant development. Wind mapping and validation techniques developed at the National Wind Technology Center (NWTC) along with collaborations with U.S. companies have produced high-resolution maps of the United States that provide wind plant developers with accurate estimates of the wind resource potential. State Wind Maps International Wind Resource Maps Dynamic Maps, GIS Data, and Analysis Tools Due to the existence of special use airspace (SUA) (i.e., military airspace

405

Balancing of Wind Power.  

E-Print Network (OSTI)

?? In the future, renewable energy share, especially wind power share, in electricity generation is expected to increase. Due to nature of the wind, wind… (more)

Ülker, Muhammed Akif

2011-01-01T23:59:59.000Z

406

Development of Wind-and-React Bi-2212 Accelerator Magnet Technology  

E-Print Network (OSTI)

28, 2007 Development of Wind-and-React Bi–2212 Acceleratorsystems. We believe that a Wind-and-React (W&R) process isTemperature Super- conductor, Wind-and-React, Bi 2 Sr 2 CaCu

2008-01-01T23:59:59.000Z

407

Two-Way Feedback Interaction between the Thermohaline and Wind-Driven Circulations  

Science Conference Proceedings (OSTI)

The thermohaline circulation (THC) affects the meridional atmospheric temperature gradient and therefore the atmospheric wind and the wind-driven ocean circulation. The wind-driven circulation (WDC), in turn, affects the THC by the advection of ...

Douglas G. MacMynowski; Eli Tziperman

2006-05-01T23:59:59.000Z

408

Stability Parameters and Wind-Stress Coefficients under Various Atmospheric Conditions  

Science Conference Proceedings (OSTI)

Stability parameters and wind-stress coefficients under various atmospheric conditions are related to wind velocity and air-sea temperature difference. Readily applicable formulae, without iterative computations, of wind-stress coefficients under ...

Jin Wu

1986-06-01T23:59:59.000Z

409

Wind-Stress Coefficients at Light Winds  

Science Conference Proceedings (OSTI)

The increase of the wind-stress coefficient with wind velocity was found to start with winds as light as 3 m s?1, below which, following the formula for aerodynamically smooth flows, the wind-stress coefficient decreases as the wind velocity ...

Jin Wu

1988-12-01T23:59:59.000Z

410

Assessment of research needs for wind turbine rotor materials technology  

DOE Green Energy (OSTI)

Wind-driven power systems is a renewable energy technology that is still in the early stages of development. Wind power plants installed in early 1980s suffered structural failures chiefly because of incomplete understanding of wind forces (turbulent), in some cases because of poor product quality. Failures of rotor blades are now somewhat better understood. This committee has examined the experience base accumulated by wind turbines and the R and D programs sponsored by DOE. It is concluded that a wind energy system such as is described is within the capability of engineering practice; however because of certain gaps in knowledge, and the presence of only one major integrated manufacturer of wind power machines in the USA, a DOE R and D investment is still required.

Not Available

1991-01-01T23:59:59.000Z

411

Turbulence-Turbine Interaction: The Basis for the Development of the TurbSim Stochastic Simulator  

DOE Green Energy (OSTI)

A combination of taller wind turbines with more flexible rotors and towers operating in turbulent conditions that are not well understood is contributing to much higher than anticipated maintenance and repairs costs and is associated with lower energy production. This report documents evidence of this and offers the turbine designers an expanded tool that resolves many of these shortcomings.

Kelley, N. D.

2011-11-01T23:59:59.000Z

412

Space and Time Variations in Turbulence during the Manhattan Midtown 2005 Field Experiment  

Science Conference Proceedings (OSTI)

The Manhattan Midtown-2005 field experiment (MID05) collected turbulence observations at 12 street-level sites (at 3-m height) and at 5 rooftop sites (at 220-m average height). The MID05 observations of 30-min averaged standard deviations of wind ...

S. R. Hanna; Y. Zhou

2009-11-01T23:59:59.000Z

413

Measurements of Turbulence in the Upper-Ocean Mixing Layer Using Autosub  

Science Conference Proceedings (OSTI)

The rate of dissipation of turbulent kinetic energy has been measured with airfoil probes mounted on an autonomous vehicle, Autosub, on constant-depth legs at 2–10 m below the surface in winds up to 14 m s?1. The observations are mostly in an ...

S. A. Thorpe; T. R. Osborn; J. F. E. Jackson; A. J. Hall; R. G. Lueck

2003-01-01T23:59:59.000Z

414

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

415

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

416

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...

417

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

418

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...

419

Model for simulating rotational data for wind turbine applications  

DOE Green Energy (OSTI)

This document describes a wind simulation model to be used in relation to wind turbine operations. The model is a computer code written in FORTRAN 77. The model simulates turbulence and mean wind effects as they are experienced at a rotating point on the blade of either a horizontal-axis wind turbine (HAWT) or a vertical-axis wind turbine (VAWT). The model is fast, requiring 15 to 120 seconds of VAX execution time to produce a simulation and related statistics. The model allows the user to set a number of wind parameters so that he may evaluate the uncertainty of model results as well as their typical values. When this capability is combined with short execution time, the user can quickly produce a number of simulations based on reasonable variation of input parameters and can use these simulations to obtain a range of wind turbine responses to the turbulence. This ability is important because some of the wind parameters that cannot be precisely evaluated should be prescribed over a range of values. This document is essentially a user's guide. Its features include theoretical derivations, samples of output, comparisons of measured and modeled results, a listing of the FORTRAN code, a glossary for the code, and the input and output of a sample run.

Powell, D.C.; Connell, J.R.

1986-04-01T23:59:59.000Z

420

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

Note: This page contains sample records for the topic "temperature turbulence wind" 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

The Solar Wind and Its Interaction with the Interstellar Medium  

E-Print Network (OSTI)

to the solar wind speed and have an initial temperature equal to the solar wind energy, about 1 keV. Figure 7 and their subsequent acceleration to the solar wind speed at the expense of the flow energy in the thermal solar wind that the slowdown is about 17% near the TS (Richardson et al. 2008a), so roughly 30% of the solar wind flow energy

Richardson, John

422

Coronal Heating versus Solar Wind Acceleration  

E-Print Network (OSTI)

Parker's initial insights from 1958 provided a key causal link between the heating of the solar corona and the acceleration of the solar wind. However, we still do not know what fraction of the solar wind's mass, momentum, and energy flux is driven by Parker-type gas pressure gradients, and what fraction is driven by, e.g., wave-particle interactions or turbulence. SOHO has been pivotal in bringing these ideas back to the forefront of coronal and solar wind research. This paper reviews our current understanding of coronal heating in the context of the acceleration of the fast and slow solar wind. For the fast solar wind, a recent model of Alfven wave generation, propagation, and non-WKB reflection is presented and compared with UVCS, SUMER, radio, and in-situ observations at the last solar minimum. The derived fractions of energy and momentum addition from thermal and nonthermal processes are found to be consistent with various sets of observational data. For the more chaotic slow solar wind, the relative roles of steady streamer-edge flows (as emphasized by UVCS abundance analysis) versus bright blob structures (seen by LASCO) need to be understood before the relation between streamer heating and and slow-wind acceleration can be known with certainty. Finally, this presentation summarizes the need for next-generation remote-sensing observations that can supply the tight constraints needed to unambiguously characterize the dominant physics.

Steven R. Cranmer

2004-09-29T23:59:59.000Z

423

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

424

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

425

Wind turbine  

DOE Patents (OSTI)

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01T23:59:59.000Z

426

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

427

An Accuracy Goal for a Comprehensive Satellite Wind Measuring System  

Science Conference Proceedings (OSTI)

Variational analysis with a geostrophic constraint is used to estimate a critical accuracy for a satellite lidar wind measuring system. This accuracy is such that the combination of satellite winds with satellite temperatures can produce analyses ...

Norman A. Phillips

1983-01-01T23:59:59.000Z

428

New England Wind Forum: Wind Power Economics  

Wind Powering America (EERE)

State Activities Projects in New England Building Wind Energy in New England Wind Resource Wind Power Technology Economics Cost Components Determining Factors Influencing Wind Economics in New England How does wind compare to the cost of other electricity options? Markets Siting Policy Technical Challenges Issues Small Wind Large Wind Newsletter Perspectives Events Quick Links to States CT MA ME NH RI VT Bookmark and Share Wind Power Economics Long-Term Cost Trends Since the first major installations of commercial-scale wind turbines in the 1980s, the cost of energy from wind power projects has decreased substantially due to larger turbine generators, towers, and rotor lengths; scale economies associated with larger projects; improvements in manufacturing efficiency, and technological advances in turbine generator and blade design. These technological advances have allowed for higher generating capacities per turbine and more efficient capture of wind, especially at lower wind speeds.

429

New England Wind Forum: Large Wind  

Wind Powering America (EERE)

Small Wind Small Wind Large Wind Newsletter Perspectives Events Quick Links to States CT MA ME NH RI VT Bookmark and Share Large Wind When establishing wind farms, wind energy developers generally approach landowners where they want to build. Interest in wind farms is frequently spurred by external pressures such as tax and other financial incentives and legislative mandates. Since each situation is influenced by local policies and permitting, we can only provide general guidance to help you learn about the process of installing wind turbines. Publications Wind Project Development Process Permitting of Wind Energy Facilities: A Handbook. (August 2002). National Wind Coordinating Collaborative. Landowner Frequently Asked Questions and Answers. (August 2003). "State Wind Working Group Handbook." pp. 130-133.

430

NREL: Wind Research - International Wind Resource Maps  

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

Wind Resource Maps NREL is helping to develop high-resolution projections of wind resources worldwide. This allows for more accurate siting of wind turbines and has led to the...

431

NREL: Wind Research - Wind Project Development Updates  

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

Wind Project Development Updates A 2.3 megawatt Siemens wind turbine nacelle on route to the Record Hill Wind project in Roxbury, Maine. January 14, 2013 As a result of the...

432

Assessment of RANS-based turbulent combustion models for prediction of gas turbine emissions: turbulence model and reaction mechanism effects  

DOE Green Energy (OSTI)

The goal of this study is to assess current, commonly applied turbulence and combustion models with respect to their performance in gas-turbine combustion (GTC). Reynolds Averaged Navier-Stokes (RANS)-based turbulence and chemistry models are two primary factors influencing the uncertainty in predicting turbulent combustion characteristics, especially for GTC. RANS-based methods are the design tools of choice in the gas turbine industry due to the high computational costs of LES (Large Eddy Simulation). In this study, lean premixed combustion of methane was simulated using two different reduced mechanisms (ARM9 and ARM19) along with the Eddy Dissipation Concept (EDC) turbulent chemistry interaction model to calculate the CO and NOx emissions. The effect of turbulence models was assessed by considering two different models. Both of the models tested performed well in the prediction of temperature and major species profiles. Predicted values of NO emission profiles showed an average difference of ±5 ppm compared to experimental values. Computed intermediate species profiles showed large qualitative and quantitative errors when compared with the experimental data. These discrepancies, especially the intermediate species hydrogen, indicate the challenges these reduced mechanisms and turbulence models can present when modeling pollutant emissions from gas turbine combustors.

Nanduri, J.R.; Celik, I.B.; Strakey, P.A.; Parsons, D.R.

2007-10-01T23:59:59.000Z

433

An investigation of wind loads on solar collectors. Appendix II - net pressure coefficients. Final report  

SciTech Connect

A wind-tunnel study of a series of model solar-collector installations (flat-plate collectors) immersed in a thick turbulent shear layer was undertaken in order to determine design wind loads on such installations. Wind tunnel measurements were made of the mean and fluctuating pressures on a model of a single flat-plate collector which was a component of different multi-panel installations. The pressures were spatially integrated over the top and bottom of the single collector separately.

Tieleman, H.W.; Akins, R.E.; Sparks, P.R.

1980-01-01T23:59:59.000Z

434

Stabilized space---time computation of wind-turbine rotor aerodynamics  

Science Conference Proceedings (OSTI)

We show how we use the Deforming-Spatial-Domain/Stabilized Space---Time (DSD/SST) formulation for accurate 3D computation of the aerodynamics of a wind-turbine rotor. As the test case, we use the NREL 5MW offshore baseline wind-turbine rotor. This class ... Keywords: DSD/SST formulation, Rotating turbulent flow, Space---time variational multiscale method, Torque values, Wind-turbine aerodynamics

Kenji Takizawa; Bradley Henicke; Tayfun E. Tezduyar; Ming-Chen Hsu; Yuri Bazilevs

2011-09-01T23:59:59.000Z

435

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

436

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

437

An Examination of the AGCM Simulated Surface Wind Stress and Low-Level Winds over the Tropical Pacific Ocean  

Science Conference Proceedings (OSTI)

The monthly mean surface wind stress and winds in the lower troposphere for 1986–92 simulated by the Center for Ocean–Land–Atmosphere Studies atmospheric general circulation model (AGCM) forced with observed sea surface temperature (SST) is ...

Bohua Huang; J. Shukla

1997-05-01T23:59:59.000Z

438

GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM  

Science Conference Proceedings (OSTI)

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

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

2012-11-10T23:59:59.000Z

439

Topic: Wind Engineering  

Science Conference Proceedings (OSTI)

Topic: Wind Engineering. Forty-Fourth Meeting of the UJNR Panel on Wind and Seismic Effects. NIST researchers collected ...

2011-08-31T23:59:59.000Z

440

Extreme Wind Speeds: Publications  

Science Conference Proceedings (OSTI)

... "Algorithms for Generating Large Sets of Synthetic Directional Wind Speed Data for Hurricane, Thunderstorm, and Synoptic Winds," NIST Technical ...

2013-08-19T23:59:59.000Z

Note: This page contains sample records for the topic "temperature turbulence wind" 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

NREL: Wind Research - Offshore Wind Research  

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

Options Site Map Printable Version Offshore Standards and Testing NREL's Offshore Wind Testing Capabilities 35 years of wind turbine testing experience Custom high speed data...

442

Multiscalar measurements of turbulence-chemistry interactions in nonpremixed flames  

DOE Green Energy (OSTI)

Selected results from experiments conducted over the past several years involving simultaneous multiscalar point measurements in turbulent nonpremixed flames are reviewed in this paper. In these experiments, spontaneous Raman scattering and Rayleigh scattering measurements of the major species and temperature were combined with laser-induced fluorescence measurements of minor species. The most important feature of these experiments is that they provide detailed data on the instantaneous relationships among species concentration, temperature, and derived scalar quantities that reflect the state of mixing or the progress of reaction. The data allow quantitative comparisons of the thermochemical states in turbulent flames with those in idealized representations, such as steady strained laminar flames, perfectly stirred reactors, or adiabatic equilibrium. The data may also be compared with results (measured or calculated) from unsteady laminar flames and from direct numerical simulations (DNS) of turbulent reacting flows. such comparisons provide insights into the fundamental nature of turbulence-chemistry interactions, and they allow one to examine the validity of some of the basic assumptions that turbulent combustion models are built upon. Furthermore, these data allow quantitative evaluations of the predictive accuracy, strengths, and limitations of a wide variety of combustions models.

Barlow, R.S.

1995-12-01T23:59:59.000Z

443

Formation Mechanisms of the Extreme High Surface Air Temperature of 40.9°C Observed in the Tokyo Metropolitan Area: Considerations of Dynamic Foehn and Foehnlike Wind  

Science Conference Proceedings (OSTI)

A record-breaking high surface air temperature in Japan of 40.9°C was observed on 16 August 2007 in Kumagaya, located 60 km northwest of central Tokyo. In this study, the formation mechanisms of this extreme high temperature event are ...

Yuya Takane; Hiroyuki Kusaka

2011-09-01T23:59:59.000Z

444

An investigation of wind loads on solar collectors. Final report  

SciTech Connect

A wind-tunnel study of a series of model solar-collector installations (flat-plate collectors) immersed in a thick turbulent shear layer was undertaken in order to determine design wind loads on such installations. Wind tunnel measurements were made of the mean and fluctuating pressures on a model of a single flat-plate collector which was a component of different multi-panel installations. The pressures were spatially integrated over the top and bottom surface of the single collector separately.

Tieleman, H.W.; Akins, R.E.; Sparks, P.R.

1980-01-01T23:59:59.000Z

445

NREL: Wind Research - Small Wind Turbine Development  

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

Small Wind Turbine Development Small Wind Turbine Development A photo of Southwest Windpower's Skystream wind turbine in front of a home. PIX14936 Southwest Windpower's Skystream wind turbine. A photo of the Endurance wind turbine. PIX15006 The Endurance wind turbine. A photo of the Atlantic Orient Corporation 15/50 wind turbine at the National Wind Technology Center. PIX07301 The Atlantic Orient Corporation 15/50 wind turbine at the National Wind Technology Center. NREL supports continued market expansion of small wind turbines by funding manufacturers through competitive solicitations (i.e., subcontracts and/or grants) to refine prototype systems leading to commercialization. Learn more about the turbine development projects below. Skystream NREL installed and tested an early prototype of this turbine at the

446

NREL: Wind Research - Small Wind Turbine Webinars  

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

Small Wind Turbine Webinars Small Wind Turbine Webinars Here you will find webinars about small wind turbines that NREL hosted. Introducing WindLease(tm): Making Wind Energy Affordable NREL and the American Solar Energy Society (ASES) Wind Division co-hosted this webinar. (Text Version.) Date: August 1, 2013 Run Time: 40 minutes Joe Hess, VP of Business Development at United Wind, described United Wind's WindQuote and WindLease Program and explained the process from the dealer's and consumer's perspective. Texas Renewable Energy Industries Association NREL and the American Solar Energy Society (ASES) Wind Division co-hosted this webinar. (Text Version). Date: March 7, 2013 Run Time: 1 hour Russel Smith, Texas Renewable Energy Industries Association executive director and co-founder, provided an overview of the trade association

447

New England Wind Forum: Small Wind  

Wind Powering America (EERE)

Wind for Schools Project Funding Case Studies: Thomas Harrison Middle School, Virginia Wind for Schools Project Funding Case Studies: Thomas Harrison Middle School, Virginia August 26, 2013 Workshop Explores Information's Role in Wind Project Siting: A Wind Powering America Success Story November 19, 2012 More News Subscribe to News Updates Events Renewable Energy Market Update Webinar January 29, 2014 Strategic Energy Planning: Webinar February 26, 2014 Introduction to Wind Systems March 10, 2014 More Events Publications 2012 Market Report on Wind Technologies in Distributed Applications August 12, 2013 More Publications Features Sign up for the New England Wind Forum Newsletter. New England Wind Forum About the New England Wind Forum New England Wind Energy Education Project Historic Wind Development in New England State Activities Projects in New England

448

Neutrino-driven wind and wind termination shock in supernova cores  

E-Print Network (OSTI)

The neutrino-driven wind from a nascent neutron star at the center of a supernova expands into the earlier ejecta of the explosion. Upon collision with this slower matter the wind material is decelerated in a wind termination shock. By means of hydrodynamic simulations in spherical symmetry we demonstrate that this can lead to a large increase of the wind entropy, density, and temperature, and to a strong deceleration of the wind expansion. The consequences of this phenomenon for the possible r-process nucleosynthesis in the late wind still need to be explored in detail. Two-dimensional models show that the wind-ejecta collision is highly anisotropic and could lead to a directional dependence of the nucleosynthesis even if the neutrino-driven wind itself is spherically symmetric.

A. Arcones; L. Scheck; H. -Th. Janka

2006-12-21T23:59:59.000Z

449

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

450

Aerodynamic interference between two Darrieus wind turbines  

DOE Green Energy (OSTI)

The effect of aerodynamic interference on the performance of two curved bladed Darrieus-type vertical axis wind turbines has been calculated using a vortex/lifting line aerodynamic model. The turbines have a tower-to-tower separation distance of 1.5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement (1) was significant only when the line of turbine centers was coincident with the ambient wind direction, (2) increased with increasing tipspeed ratio, and (3) is due more to induced flow angularities downstream than to speed deficits near the downstream turbine.

Schatzle, P.R.; Klimas, P.C.; Spahr, H.R.

1981-04-01T23:59:59.000Z

451

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

452

An Assessment of High-Temperature Superconductors for High-Field SMES Systems: U.S. Department of Energy -- EPRI Wind Turbine Verification Program  

Science Conference Proceedings (OSTI)

This study evaluated superconducting magnetic energy storage (SMES) systems made of different high temperature superconductor (HTS) materials. The research addressed a broad range of practical issues associated with building a high-field HTS SMES system.

1999-12-15T23:59:59.000Z

453

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

SciTech Connect

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

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

2010-05-15T23:59:59.000Z

454

Description of the Columbia Basin Wind Energy Study (CBWES)  

SciTech Connect

The purpose of this Technical Report is to provide background information about the Columbia Basin Wind Energy Study (CBWES). This study, which was supported by the U.S. Department of Energy’s Wind and Water Power Program, was conducted from 16 November 2010 through 21 March 2012 at a field site in northeastern Oregon. The primary goal of the study was to provide profiles of wind speed and wind direction over the depth of the boundary layer in an operating wind farm located in an area of complex terrain. Measurements from propeller and vane anemometers mounted on a 62 m tall tower, Doppler Sodar, and Radar Wind Profiler were combined into a single data product to provide the best estimate of the winds above the site during the first part of CBWES. An additional goal of the study was to provide measurements of Turbulence Kinetic Energy (TKE) near the surface. To address this specific goal, sonic anemometers were mounted at two heights on the 62 m tower on 23 April 2011. Prior to the deployment of the sonic anemometers on the tall tower, a single sonic anemometer was deployed on a short tower 3.1 m tall that was located just to the south of the radar wind profiler. Data from the radar wind profiler, as well as the wind profile data product are available from the Atmospheric Radiation Measurements (ARM) Data Archive (http://www.arm.gov/data/campaigns). Data from the sonic anemometers are available from the authors.

Berg, Larry K.; Pekour, Mikhail S.; Nelson, Danny A.

2012-10-01T23:59:59.000Z

455

Probing the Vibrational Relaxation of N2 and O2 by Use of CARS Spectroscopy to Model NTE-Turbulence  

E-Print Network (OSTI)

The thermochemical dynamics associated with hypersonic flight and turbulent flow is vital to understanding the effects that hypersonic turbulence has on objects or vehicles traveling at speeds above Mach 5 (~ 1708 m/s). Non-thermochemical equilibrium (NTE) exists downstream of strong shock fronts and encountered in the shear layers from hypersonic flight, and coupled with turbulence, it has significant effects on flow dynamics. NTE, characterized by high vibrational temperatures of N2 and O2, was observed, and the relaxation processes were measured to obtain time-resolved results. By inducing cold-flow NTE via RF-plasma, species in the flow were probed to determine specific vibrational temperatures at particular distances and times following initial NTE-preparation. The detection technique used in the experiment was coherent anti-Stokes Raman spectroscopy (CARS) and variations of this laser-based technique were optimized to maximize accuracy and signal-to-noise in the vibrational relaxation measurements. It was found that the boxCARS variant was most successful in probing the v=1 --> v=0 vibrational transition associated with the measurement. Also a dual pump-beam CARS setup enabled the probing of both N2 and O2 simultaneously; however, in this report only N2 vibrational relaxation was modeled because the lifetime of vibrationally-excited (v=1) O2 was too short and the O2 vibrational temperature was too low to model. The CARS spectra were obtained in a subsonic wind tunnel with a flow velocity of approximately 30 m/s and probing distances from 4.4-39.4 cm downstream the plasma. Five averaged vibrational temperature values were determined and they yielded a decay from 1882 ± 46 K (4.4 cm from plasma) to 1010 ± 16 K (39.4 cm from plasma) showing the relative rate of vibrational relaxation of N2. The vibrational relaxation was also modeled as a function of time after passing through the plasma, and a kinetic simulation was fit to the results. The spectral decay of the v=1 peak relative to v=0 (Iv=1/Iv=0) was found and compared to the decay of the vibrational temperature. Data analysis revealed that the results were in agreement with theory and the observed vibrational relaxation of N2 fit the simulated kinetic model accurately.

Dean, Jacob

2009-06-09T23:59:59.000Z

456

NREL: Wind Research - Site Wind Resource Characteristics  

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

Site Wind Resource Characteristics Site Wind Resource Characteristics A graphic showing the location of National Wind Technology Center and its wind power class 2. Click on the image to view a larger version. Enlarge image This graphic shows the wind power class at the National Wind Technology Center. You can download a printable copy. The National Wind Technology Center (NWTC) is on the Great Plains just miles from the Rocky Mountains. The site is flat and covered with short grasses. The terrain and lack of obstructions make the site highly suitable for testing wind turbines. Take a tour of the NWTC and its facilities to better understand its location and layout. Another prime feature of the NWTC is the strong directionality of the wind - most of the strong winds come within a few degrees of 285°. West of

457

NREL: Wind Research - Offshore Wind Research  

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

Offshore Wind Research Offshore Wind Research Photo of a European offshore wind farm. Early progress in European Offshore Wind Energy over the last decade provides a glimpse into the vast potential of the global offshore resource. For more than eight years, NREL has worked with the Department of Energy to become an international leader in offshore wind energy research. Capabilities NREL's offshore wind capabilities focus on critical areas that reflect the long-term needs of the offshore wind energy industry and the U.S. Department of Energy including: Offshore Design Tools and Methods Offshore Standards and Testing Energy Analysis of Offshore Systems Offshore Wind Resource Characterization Grid Integration of Offshore Wind Key Research NREL documented the status of offshore wind energy in the United States in

458

Horizon Wind  

E-Print Network (OSTI)

The Washington Department of Fish and Wildlife (WDFW) does not have regulatory authority specific to wind power development at this time. WDFW is an agency with environmental expertise as provided for through the Washington Administrative Code (WAC) 197-11-920. Comments related to environmental impacts are provided to regulatory authorities through the State Environmental Policy Act (SEPA) Revised Code of Washington (RCW) 43.21C review process.

Cover Photo; Nina Carter; Heath Packard; Lisa Paribello; Craig Dublanko; Dana Peck; Nicole Hughes; Bill Robinson; Robert Kruse; Arlo Corwin; Joe Buchanan; Ted Clausing; Eric Cummins; Travis Nelson; Eric Pentico; Mike Ritter; Jeff Tayer; James Watson; William Weiler; David Mcclure

2009-01-01T23:59:59.000Z

459

Utility Wind Integration Group Distributed Wind/Solar Interconnection...  

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

Utility Wind Integration Group Distributed WindSolar Interconnection Workshop Utility Wind Integration Group Distributed WindSolar Interconnection Workshop May 21, 2013 8:00AM...

460

The Wind Energy Outlook Scenarios 1 India Wind Energy  

E-Print Network (OSTI)

1 ?Status of wind energy in India ????????????????????6 Wind energy in India????????????????????????????????????????????????????????????????????????????????????7 Wind power resource assessment?????????????????????????????????????????????????????????6 Wind power installations by state?????????????????????????????????????????????????????????8

unknown authors

2012-01-01T23:59:59.000Z

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


461

Anemometer Data (Wind Speed, Direction) for Ugashik, AK (2001 - 2002) |  

Open Energy Info (EERE)

0 0 Varnish cache server Browse Upload data GDR 429 Throttled (bot load) Error 429 Throttled (bot load) Throttled (bot load) Guru Meditation: XID: 2142278290 Varnish cache server Anemometer Data (Wind Speed, Direction) for Ugashik, AK (2001 - 2002) Dataset Summary Description Wind data collected from Ugashik Traditional Village in Alaska from an anemometer as part of the Native American anemometer loan program. Monthly mean wind speed is available for 2001 through 2002, as is wind direction and turbulence data. Data is reported from a height of 20 m. The data was originally made available by Wind Powering America, a DOE Office of Energy Efficiency & Renewable Energy (EERE) program. A dynamic map displaying all available data from DOE anemometer loan programs is available http://www.windpoweringamerica.gov/anemometerloans/projects.asp.

462

Anemometer Data (Wind Speed, Direction) for Tanana, AK (2001 - 2002) |  

Open Energy Info (EERE)

40 40 Varnish cache server Anemometer Data (Wind Speed, Direction) for Tanana, AK (2001 - 2002) Dataset Summary Description Wind data collected from Tanana Village in Alaska from an anemometer as part of the Native American anemometer loan program. Monthly mean wind speed is available for 2001 through 2002, as is wind direction and turbulence data. Data is reported from a height of 20 m. The data was originally made available by Wind Powering America, a DOE Office of Energy Efficiency & Renewable Energy (EERE) program. A dynamic map displaying all available data from DOE anemometer loan programs is available http://www.windpoweringamerica.gov/anemometerloans/projects.asp. Source EERE Date Released November 09th, 2010 (4 years ago) Date Updated November 09th, 2010 (4 years ago)

463

Parameterization of Wind Farms in Climate Models  

Science Conference Proceedings (OSTI)

For assessing the impacts of wind farms on regional climate, wind farms may be represented in climate models by an increase in aerodynamic roughness length. Studies employing this method have found near-surface temperature changes of 1-2 K over ...

Anna C. Fitch; Joseph B. Olson; Julie K. Lundquist

464

Parameterization of Wind Farms in Climate Models  

Science Conference Proceedings (OSTI)

For assessing the impacts of wind farms on regional climate, wind farms may be represented in climate models by an increase in aerodynamic roughness length. Studies employing this method have found near-surface temperature changes of 1–2 K over ...

Anna C. Fitch; Joseph B. Olson; Julie K. Lundquist

2013-09-01T23:59:59.000Z

465

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

466

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

467

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

468

Rotationally sampled wind characteristics for several rotor sizes using laser anemometer measurements  

DOE Green Energy (OSTI)

The concept of measuring the wind velocity rotationally around crosswind circles using a circle-scanning Doppler laser anemometer is investigated to determine the technique's suitability as an effective, simple, economical, and nonintrusive method for estimation turbulence at a wind turbine rotor. Estimates of wind features obtained using the lidar technique are compared to actual wind measurements obtained using a vertical plane array of anemometers, and to other estimates generated using a single-tower technique. Although the lack of a common data set precludes a firm conclusion regarding the lidar method's accuracy, it appears that the rotationally scanning lidar has the potential of becoming an excellent tool for measuring turbulent wind around the disk of rotation of a turbine blade. 11 refs., 21 figs., 2 tabs.

Connell, J.R.; Morris, V.R.

1989-02-01T23:59:59.000Z

469

Energy Basics: Wind Power Animation  

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

Energy Basics Renewable Energy Printable Version Share this resource Biomass Geothermal Hydrogen Hydropower Ocean Solar Wind Wind Turbines Wind Resources Wind Power...

470

Energy Basics: Wind Energy Resources  

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

Energy Basics Renewable Energy Printable Version Share this resource Biomass Geothermal Hydrogen Hydropower Ocean Solar Wind Wind Turbines Wind Resources Wind Energy...

471

Energy Basics: Wind Energy Technologies  

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

Energy Basics Renewable Energy Printable Version Share this resource Biomass Geothermal Hydrogen Hydropower Ocean Solar Wind Wind Turbines Wind Resources Wind Energy...

472

Energy Basics: Wind Energy Technologies  

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

Photo of a hilly field, with six visible wind turbines spinning in the wind. Wind energy technologies use the energy in wind for practical purposes such as generating...

473

Solar Wind | Open Energy Information  

Open Energy Info (EERE)

Wind Jump to: navigation, search Name Solar Wind Place Krasnodar, Romania Zip 350000 Sector Solar, Wind energy Product Russia-based PV product manufacturer. Solar Wind manufactures...

474

EERE: Wind Program Home Page  

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

wind projects and offshore wind resource potential. Offshore Wind R&D DOE makes strategic research & deployment investments to launch domestic offshore wind industry....

475

2011 Wind Technologies Market Report  

E-Print Network (OSTI)

A. 2010. Impact of Wind Energy Installations on DomesticUniversity. American Wind Energy Association (AWEA). 2012a.D.C. : American Wind Energy Association. American Wind

Bolinger, Mark

2013-01-01T23:59:59.000Z

476

2011 Wind Technologies Market Report  

E-Print Network (OSTI)

and K. Porter. 2011. Wind Power and Electricity Markets.41 6. Wind Power Priceat Various Levels of Wind Power Capacity Penetration Wind

Bolinger, Mark

2013-01-01T23:59:59.000Z

477

A spray-suppression model for turbulent combustion  

SciTech Connect

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

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

2000-02-14T23:59:59.000Z

478

A spray-suppression model for turbulent combustion  

DOE Green Energy (OSTI)

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

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

2000-02-14T23:59:59.000Z

479