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


1

Implicit Large Eddy Simulation  

National Nuclear Security Administration (NNSA)

Implicit Implicit Large Eddy Simulation (ILES) for High Reynolds Number Flows Len Margolin Applied Physics Division Los Alamos National Laboratory Collaborators: 1. Bill Rider (LANL) 2. Piotr Smolarkiewicz (NCAR) 3. Andrzej Wysogrodski (NCAR) 4. Fernando Grinstein (NRL) len@lanl.gov 1 Implicit Large Eddy Simulation Outline: * What is ILES? * What are its advantages? * Historical perspective * Why does it work? * Some examples len@lanl.gov 2 What is ILES ILES is the direct application of a fluid solver to a high Reynolds number fluid flow with no explicit turbulence model. · The truncation terms of the algorithm serve as an effective model of the effects of the unresolved scales. · Fluid solvers based on Nonoscillatory Finite Volume (NFV) approximations work effectively for ILES. · Fluid solvers based on pseudospectral methods, leapfrog methods, advective form methods, etc. do not work

2

Large-Eddy Simulation of Contrails  

Science Conference Proceedings (OSTI)

Numerical simulations of contrails have been performed to investigate the role of various external parameters and physical processes in the life cycle of contrails. The general idea underlying the model is that of a large-eddy model. The model ...

Andreas Chlond

1998-03-01T23:59:59.000Z

3

Large-Eddy Simulation: How Large is Large Enough?  

Science Conference Proceedings (OSTI)

The length scale evolution of various quantities in a clear convective boundary layer (CBL), a stratocumulus-topped boundary layer, and three radiatively cooled (smoke cloud) convective boundary layers are studied by means of large-eddy ...

Stephan R. de Roode; Peter G. Duynkerke; Harm J. J. Jonker

2004-02-01T23:59:59.000Z

4

Large-Eddy Simulation for Green Energy and Propulsion Systems...  

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

Large-Eddy Simulation for Green Energy and Propulsion Systems PI Name: Umesh Paliath PI Email: paliath@ge.com Institution: General Electric Allocation Program: INCITE Allocation...

5

Evaluating Large-Eddy Simulations Using Volume Imaging Lidar Data  

Science Conference Proceedings (OSTI)

The authors apply data analysis techniques that demonstrate the power of using volume imaging lidar observations to evaluate several aspects of large-eddy simulations (LESs). They present observations and simulations of an intense and spatially ...

Shane D. Mayor; Gregory J. Tripoli; Edwin W. Eloranta

2003-07-01T23:59:59.000Z

6

Large-Eddy Simulation of the Convective Atmospheric Boundary Layer  

Science Conference Proceedings (OSTI)

Large-eddy simulations of a free convective atmospheric boundary layer with an overlying capping inversion are considered. Attention is given to the dependence of the results upon the various factors influencing the simulation: the subgrid model, ...

P. J. Mason

1989-06-01T23:59:59.000Z

7

A Large Eddy Simulation Intercomparison Study of Shallow Cumulus Convection  

Science Conference Proceedings (OSTI)

This paper reports an intercomparison study on undisturbed trade wind cumulus convection under steady-state conditions as observed during the Barbados Oceanographic and Meteorological Experiment (BOMEX) with 10 large eddy simulation (LES) models. ...

A. Pier Siebesma; Christopher S. Bretherton; Andrew Brown; Andreas Chlond; Joan Cuxart; Peter G. Duynkerke; Hongli Jiang; Marat Khairoutdinov; David Lewellen; Chin-Hoh Moeng; Enrique Sanchez; Bjorn Stevens; David E. Stevens

2003-05-01T23:59:59.000Z

8

Large-Eddy Simulation of Decaying Stably Stratified Turbulence  

Science Conference Proceedings (OSTI)

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

David A. Siegel; J. Andrzej Domaradzki

1994-11-01T23:59:59.000Z

9

Comparison of In-Canopy Flux Footprints between Large-Eddy Simulation and the Lagrangian Simulation  

Science Conference Proceedings (OSTI)

Flux footprints for neutral shear-driven canopy flows are evaluated using large-eddy simulation (LES) and a Lagrangian stochastic (LS) model. The Lagrangian stochastic model is driven by flow statistics derived from the large-eddy simulation. LES ...

T. V. Prabha; M. Y. Leclerc; D. Baldocchi

2008-08-01T23:59:59.000Z

10

Large-Eddy Simulation of Wind-Plant Aerodynamics: Preprint  

DOE Green Energy (OSTI)

In this work, we present results of a large-eddy simulation of the 48 multi-megawatt turbines composing the Lillgrund wind plant. Turbulent inflow wind is created by performing an atmospheric boundary layer precursor simulation and turbines are modeled using a rotating, variable-speed actuator line representation. The motivation for this work is that few others have done wind plant large-eddy simulations with a substantial number of turbines, and the methods for carrying out the simulations are varied. We wish to draw upon the strengths of the existing simulations and our growing atmospheric large-eddy simulation capability to create a sound methodology for performing this type of simulation. We have used the OpenFOAM CFD toolbox to create our solver.

Churchfield, M. J.; Lee, S.; Moriarty, P. J.; Martinez, L. A.; Leonardi, S.; Vijayakumar, G.; Brasseur, J. G.

2012-01-01T23:59:59.000Z

11

Using large eddy simulations to understand flow mixing | Argonne National  

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

large eddy simulations to understand flow mixing large eddy simulations to understand flow mixing March 4, 2013 Tweet EmailPrint In nuclear power plants, turbulent flow streams of different velocity and density mix rapidly at right angles in pipes. If those mixing flow streams are of different temperatures, thermal fluctuations result on the pipe wall. Such fluctuations can damage a pipe's structure and, ultimately, cause its failure. To better understand this phenomenon and to predict the effects, scientists have developed modeling methods known as large eddy simulations (LES). LES models only the energy-carrying large scales of motion, using a filtering mechanism to account for subgrid-scale motion. Thanks to recent advances in high-performance computing, the technique has become increasingly popular for simulating unsteady flows, allowing high fidelity

12

Large-Eddy Simulation of Wind-Plant Aerodynamics  

DOE Green Energy (OSTI)

In this work, we present results of a large-eddy simulation of the 48 multi-megawatt turbines composing the Lillgrund wind plant. Turbulent inflow wind is created by performing an atmospheric boundary layer precursor simulation, and turbines are modeled using a rotating, variable-speed actuator line representation. The motivation for this work is that few others have done large-eddy simulations of wind plants with a substantial number of turbines, and the methods for carrying out the simulations are varied. We wish to draw upon the strengths of the existing simulations and our growing atmospheric large-eddy simulation capability to create a sound methodology for performing this type of simulation. We used the OpenFOAM CFD toolbox to create our solver. The simulated time-averaged power production of the turbines in the plant agrees well with field observations, except with the sixth turbine and beyond in each wind-aligned. The power produced by each of those turbines is overpredicted by 25-40%. A direct comparison between simulated and field data is difficult because we simulate one wind direction with a speed and turbulence intensity characteristic of Lillgrund, but the field observations were taken over a year of varying conditions. The simulation shows the significant 60-70% decrease in the performance of the turbines behind the front row in this plant that has a spacing of 4.3 rotor diameters in this direction. The overall plant efficiency is well predicted. This work shows the importance of using local grid refinement to simultaneously capture the meter-scale details of the turbine wake and the kilometer-scale turbulent atmospheric structures. Although this work illustrates the power of large-eddy simulation in producing a time-accurate solution, it required about one million processor-hours, showing the significant cost of large-eddy simulation.

Churchfield, M. J.; Lee, S.; Moriarty, P. J.; Martinez, L. A.; Leonardi, S.; Vijayakumar, G.; Brasseur, J. G.

2012-01-01T23:59:59.000Z

13

On Subgrid Models and Filter Operations in Large Eddy Simulations  

Science Conference Proceedings (OSTI)

Large eddy simulations use a subgrid model, which is characterized by a length scale that is often related to the scale of the computational mesh by a numerical constant, Cs. Mason and Callen argued that this subgrid model and its length scale ...

P. J. Mason; A. R. Brown

1999-07-01T23:59:59.000Z

14

Explicit Filtering and Reconstruction Turbulence Modeling for Large-Eddy Simulation of Neutral Boundary Layer Flow  

Science Conference Proceedings (OSTI)

Standard turbulence closures for large-eddy simulations of atmospheric flow based on finite-difference or finite-volume codes use eddy-viscosity models and hence ignore the contribution of the resolved subfilter-scale stresses. These eddy-...

Fotini Katopodes Chow; Robert L. Street; Ming Xue; Joel H. Ferziger

2005-07-01T23:59:59.000Z

15

Modeling of Stratocumulus Cloud Layers in a Large Eddy Simulation Model with Explicit Microphysics  

Science Conference Proceedings (OSTI)

A new large eddy simulation (LES) stratocumulus cloud model with an explicit formulation of micro-physical processes has been developed, and the results from three large eddy simulations are presented to illustrate the effects of the ...

Y. L. Kogan; M. P. Khairoutdinov; D. K. Lilly; Z. N. Kogan; Qingfu Liu

1995-08-01T23:59:59.000Z

16

Large eddy simulations of coal jet flame ignition using the direct quadrature method of moments.  

E-Print Network (OSTI)

??The Direct Quadrature Method of Moments (DQMOM) was implemented in the Large Eddy Simulation (LES) tool ARCHES to model coal particles. LES coupled with DQMOM (more)

Pedel, Julien

2012-01-01T23:59:59.000Z

17

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

18

Large-Eddy Simulation of Air Parcels in Stratocumulus Clouds: Time Scales and Spatial Variability  

Science Conference Proceedings (OSTI)

Large ensembles of air parcel trajectories driven by the (large-eddy simulation) LES-generated velocity fields from simulations of stratocumulus clouds were analyzed, focusing on statistics of air parcel in-cloud time scales, as well as their ...

Yefim L. Kogan

2006-03-01T23:59:59.000Z

19

Large-Eddy Simulations of Strongly Precipitating, Shallow, Stratocumulus-Topped Boundary Layers  

Science Conference Proceedings (OSTI)

Large-eddy simulations that incorporate a size-resolving representation of cloud water are used to study the effect of heavy drizzle on PBL structure. Simulated surface precipitation rates average about 1 mm day?1. Heavily drizzling simulations ...

Bjorn Stevens; William R. Cotton; Graham Feingold; Chin-Hoh Moeng

1998-12-01T23:59:59.000Z

20

Modeling and discretization errors in large eddy simulations of hydrodynamic and magnetohydrodynamic channel flows  

Science Conference Proceedings (OSTI)

We assess the performances of three different subgrid scale models in large eddy simulations (LES) of turbulent channel flows. Two regimes are considered: hydrodynamic and magnetohydrodynamic (i.e. in the presence of a uniform wall-normal magnetic field). ... Keywords: Channel flow, Finite-volume method, Hydrodynamic, Kinetic energy budget, Large eddy simulation, Magnetohydrodynamic, Spectral method

A. Vir; D. Krasnov; T. Boeck; B. Knaepen

2011-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Large-eddy simulation of a plane reacting jet transversely injected into supersonic turbulent channel flow  

Science Conference Proceedings (OSTI)

A plane, chemically reacting jet of fuel injected through a narrow spanwise slot into supersonic and fully turbulent air flow in a channel with isothermal, parallel walls is investigated using a semi-implicit large-eddy simulation technique. It is based ... Keywords: high-order numerical schemes, infinitely fast chemistry, large-eddy simulation, plane jet in crossflow, supersonic turbulent channel flow

Ch. Schaupp; R. Friedrich

2010-12-01T23:59:59.000Z

22

Large Eddy Simulation of the Diurnal Cycle in Southeast Pacific Stratocumulus  

Science Conference Proceedings (OSTI)

This paper describes a series of 6-day large eddy simulations of a deep, sometimes drizzling stratocumulus-topped boundary layer based on forcings from the East Pacific Investigation of Climate (EPIC) 2001 field campaign. The base simulation was ...

Peter Caldwell; Christopher S. Bretherton

2009-02-01T23:59:59.000Z

23

Large-Eddy Simulation of Moist Convection during a Cold Air Outbreak over the Gulf Stream  

Science Conference Proceedings (OSTI)

Cold air outflow over the Gulf Stream is modeled using a cloud-resolving large-eddy simulation model with three classes of precipitation. Simulations are conducted in a quasi-Lagrangian framework using an idealized sounding and uniform ...

Eric D. Skyllingstad; James B. Edson

2009-05-01T23:59:59.000Z

24

Large-Eddy Simulation of a Stratus-Topped Boundary Layer. Part I: Structure and Budgets  

Science Conference Proceedings (OSTI)

The structure of a stratus-topped boundary layer is observed through large-eddy simulation which includes the interaction of longwave radiation and turbulence processes. This simulated boundary layer has a relatively warm and dry overlying ...

Chin-Hoh Moeng

1986-12-01T23:59:59.000Z

25

Large-Eddy Simulation of Post-Cold-Frontal Continental Stratocumulus  

Science Conference Proceedings (OSTI)

Previous large-eddy simulations (LES) of stratocumulus-topped boundary layers have been exclusively set in marine environments. Boundary layer stratocumulus clouds are also prevalent over the continent but have not been simulated previously. A ...

David B. Mechem; Yefim L. Kogan; David M. Schultz

2010-12-01T23:59:59.000Z

26

Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions  

Science Conference Proceedings (OSTI)

Flow structures in an inhomogeneous neutrally stratified atmospheric boundary layer flow, obtained from large eddy simulation, are analyzed and compared with homogeneous case counterparts. The inhomogeneity is imposed in the streamwise direction ...

Ching-Long Lin; John W. Glendening

2002-08-01T23:59:59.000Z

27

Cell Broadening Revisited: Results from High-Resolution Large-Eddy Simulations of Cold Air Outbreaks  

Science Conference Proceedings (OSTI)

Large-eddy simulations (LES) have been carried out in order to investigate the structure and development of organized mesoscale cellular convection (MCC) during cold air outbreaks (CAOB) and to reevaluate results by Mller and Chlond. Some ...

M. Schrter; S. Raasch; H. Jansen

2005-06-01T23:59:59.000Z

28

Large Eddy Simulation of Internal Boundary Layers Created by a Change in Surface Roughness  

Science Conference Proceedings (OSTI)

Turbulence in a ?-mesoscale internal boundary layer (IBL) formed by a discontinuous change in surface roughness has been investigated using a large eddy simulation (LES) model to explicitly treat turbulent transport. Two cases are examined: a ...

John W. Glendening; Ching-Long Lin

2002-05-01T23:59:59.000Z

29

Study of the Aerosol Indirect Effect by Large-Eddy Simulation of Marine Stratocumulus  

Science Conference Proceedings (OSTI)

A total of 98 three-dimensional large-eddy simulations (LESs) of marine stratocumulus clouds covering both nighttime and daytime conditions were performed to explore the response of cloud optical depth (?) to various aerosol number concentrations ...

Miao-Ling Lu; John H. Seinfeld

2005-11-01T23:59:59.000Z

30

Large-Eddy Simulation of the Stable Boundary Layer with Explicit Filtering and Reconstruction Turbulence Modeling  

Science Conference Proceedings (OSTI)

Large-eddy simulation (LES) of the stably stratified atmospheric boundary layer is performed using an explicit filtering and reconstruction approach with a finite difference method. Turbulent stresses are split into the resolvable subfilter-scale ...

Bowen Zhou; Fotini Katopodes Chow

2011-09-01T23:59:59.000Z

31

Nighttime Turbulent Events in a Steep Valley: A Nested Large-eddy Simulation Study  

Science Conference Proceedings (OSTI)

This numerical study investigates the nighttime flow dynamics in Owens Valley, California. Nested high-resolution large-eddy simulation (LES) is used to resolve stable boundary layer flows within the valley. On 17 April during the 2006 Terrain-...

Bowen Zhou; Fotini Katopodes Chow

32

Large-Eddy Simulation of Roll Vortices in a Hurricane Boundary Layer  

Science Conference Proceedings (OSTI)

For the last decade, horizontal roll vortices have been often observed in hurricane boundary layers (HBLs). In this study, a large-eddy simulation is performed to explore the formation mechanism of the horizontal roll vortices and their ...

Mikio Nakanishi; Hiroshi Niino

2012-12-01T23:59:59.000Z

33

A Large-Eddy Simulation Study of Moist Convection Initiation over Heterogeneous Surface Fluxes  

Science Conference Proceedings (OSTI)

This study uses large-eddy simulations to investigate processes of moist convection initiation (CI) over heterogeneous surface fluxes. Surface energy balance is imposed via a 180 phase lag of the surface moisture flux (relative to the sensible ...

Song-Lak Kang; George H. Bryan

2011-09-01T23:59:59.000Z

34

Large Eddy Simulation of Turbulent Flow in a Marine Convective Boundary Layer with Snow  

Science Conference Proceedings (OSTI)

A large eddy simulation (LES) model, with ice phase included, has been used to study the marine convective boundary layer filled with snow. Extensions to Moeng's LES model include the diagnosis of cloud ice mixing ratio, snow precipitation, and ...

Guan-Shu Rao; Ernest M. Agee

1996-01-01T23:59:59.000Z

35

A New Cloud Physics Parameterization in a Large-Eddy Simulation Model of Marine Stratocumulus  

Science Conference Proceedings (OSTI)

A new bulk microphysical parameterization for large-eddy simulation (LES) models of the stratocumulus-topped boundary layer has been developed using an explicit (drop spectrum resolving) microphysical model as a data source and benchmark for ...

Marat Khairoutdinov; Yefim Kogan

2000-01-01T23:59:59.000Z

36

Nesting large-eddy simulations within mesoscale simulations for wind energy applications  

DOE Green Energy (OSTI)

With increasing demand for more accurate atmospheric simulations for wind turbine micrositing, for operational wind power forecasting, and for more reliable turbine design, simulations of atmospheric flow with resolution of tens of meters or higher are required. These time-dependent large-eddy simulations (LES), which resolve individual atmospheric eddies on length scales smaller than turbine blades and account for complex terrain, are possible with a range of commercial and open-source software, including the Weather Research and Forecasting (WRF) model. In addition to 'local' sources of turbulence within an LES domain, changing weather conditions outside the domain can also affect flow, suggesting that a mesoscale model provide boundary conditions to the large-eddy simulations. Nesting a large-eddy simulation within a mesoscale model requires nuanced representations of turbulence. Our group has improved the Weather and Research Forecasting model's (WRF) LES capability by implementing the Nonlinear Backscatter and Anisotropy (NBA) subfilter stress model following Kosovic (1997) and an explicit filtering and reconstruction technique to compute the Resolvable Subfilter-Scale (RSFS) stresses (following Chow et al, 2005). We have also implemented an immersed boundary method (IBM) in WRF to accommodate complex terrain. These new models improve WRF's LES capabilities over complex terrain and in stable atmospheric conditions. We demonstrate approaches to nesting LES within a mesoscale simulation for farms of wind turbines in hilly regions. Results are sensitive to the nesting method, indicating that care must be taken to provide appropriate boundary conditions, and to allow adequate spin-up of turbulence in the LES domain.

Lundquist, J K; Mirocha, J D; Chow, F K; Kosovic, B; Lundquist, K A

2008-09-08T23:59:59.000Z

37

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

38

Large-Eddy Simulation of the Onset of the Sea Breeze  

Science Conference Proceedings (OSTI)

This paper describes results from a large-eddy simulation (LES) model used in an idealized setting to simulate the onset of the sea breeze. As the LES is capable of simulating boundary layerscale, three-dimensional turbulence along with the ...

M. Antonelli; R. Rotunno

2007-12-01T23:59:59.000Z

39

Nonlocal Turbulent Mixing in the Convective Boundary Layer Evaluated from Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

Large-eddy simulation is used to simulate quasi-steady state convection in a windless mixed layer over a uniform surface with constant heat flux. Different tracers are injected at each discrete height in the model to track vertical transport of ...

Elizabeth E. Ebert; Ulrich Schumann; Roland B. Stull

1989-07-01T23:59:59.000Z

40

Large-Eddy Simulations of Trade Wind Cumuli: Investigation of Aerosol Indirect Effects  

Science Conference Proceedings (OSTI)

The effects of aerosol on warm trade cumulus clouds are investigated using a large-eddy simulation with size-resolved cloud microphysics. It is shown that, as expected, increases in aerosols cause a reduction in precipitation and an increase in ...

Huiwen Xue; Graham Feingold

2006-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Large-Eddy Simulations and Observations of Atmospheric Marine Boundary Layers above Nonequilibrium Surface Waves  

Science Conference Proceedings (OSTI)

Winds and waves in marine boundary layers are often in an unsettled state when fast-running swell generated by distant storms propagates into local regions and modifies the overlying turbulent fields. A large-eddy simulation (LES) model with the ...

Peter P. Sullivan; James B. Edson; Tihomir Hristov; James C. McWilliams

2008-04-01T23:59:59.000Z

42

Computing combustion noise by combining Large Eddy Simulations with analytical models for the propagation of waves  

E-Print Network (OSTI)

Computing combustion noise by combining Large Eddy Simulations with analytical models +++++ Presented by Ignacio Duran Abstract Two mechanisms control combustion noise generation as shown by Marble. A method to calculate combustion-generated noise has been implemented in a tool called CHORUS. The method

Paris-Sud XI, Université de

43

Conjugate Heat Transfer with Large Eddy Simulation for Gas Turbine Components.  

E-Print Network (OSTI)

Conjugate Heat Transfer with Large Eddy Simulation for Gas Turbine Components. Florent Duchaine constraint for GT (gas turbines). Most existing CHT tools are developped for chained, steady phenomena with colder walls is a key phenomenon in all chambers and is actually a main design constraint in gas turbines

Nicoud, Franck

44

Investigation of two-fluid methods for Large Eddy Simulation of spray combustion in Gas Turbines  

E-Print Network (OSTI)

Investigation of two-fluid methods for Large Eddy Simulation of spray combustion in Gas Turbines the EL method well suited for gas turbine computations, but RANS with the EE approach may also be found and coupled with the LES solver of the gas phase. The equations used for each phase and the coupling terms

45

Prediction and Analysis of Rotor Tip-Clearance Flows using Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

In order to analyze the dynamics of rotor tip-clearance flow and determine the underlying mechanism for the tip-leakage cavitation, a newly developed large-eddy simulation (LES) solver which combines an immersed-boundary method with a generalized curvilinearstructured ...

Donghyun You; Meng Wang; Parviz Moin; Rajat Mittal

2004-06-01T23:59:59.000Z

46

Steady-State Large-Eddy Simulations to Study the Stratocumulus to Shallow Cumulus Cloud Transition  

Science Conference Proceedings (OSTI)

This study presents a series of steady-state large-eddy simulations (LESs) to study the stratocumulus to shallow cumulus cloud transition. To represent the different stages of what can be interpreted as an Eulerian view of the transition, each ...

D. Chung; G. Matheou; J. Teixeira

2012-11-01T23:59:59.000Z

47

Large-Eddy Simulations of Radiatively Driven Convection: Sensitivities to the Representation of Small Scales  

Science Conference Proceedings (OSTI)

Large-eddy simulations of a smoke cloud are examined with respect to their sensitivity to small scales as manifest in either the grid spacing or the subgrid-scale (SGS) model. Calculations based on a Smagorinsky SGS model are found to be more ...

Bjorn Stevens; Chin-Hoh Moeng; Peter P. Sullivan

1999-12-01T23:59:59.000Z

48

Flow around a Complex Building: Experimental and Large-Eddy Simulation Comparisons  

Science Conference Proceedings (OSTI)

A field program to study atmospheric releases around a complex building was performed in the summers of 1999 and 2000. The focus of this paper is to compare field data with a large-eddy simulation (LES) code to assess the ability of the LES ...

Ronald Calhoun; Frank Gouveia; Joseph Shinn; Stevens Chan; Dave Stevens; Robert Lee; John Leone

2005-05-01T23:59:59.000Z

49

Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus  

Science Conference Proceedings (OSTI)

Data from the first research flight (RF01) of the second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study are used to evaluate the fidelity with which large-eddy simulations (LESs) can represent the turbulent structure of ...

Bjorn Stevens; Chin-Hoh Moeng; Andrew S. Ackerman; Christopher S. Bretherton; Andreas Chlond; Stephan de Roode; James Edwards; Jean-Christophe Golaz; Hongli Jiang; Marat Khairoutdinov; Michael P. Kirkpatrick; David C. Lewellen; Adrian Lock; Frank Mller; David E. Stevens; Eoin Whelan; Ping Zhu

2005-06-01T23:59:59.000Z

50

Large-Eddy Simulation of Flow over Two-Dimensional Obstacles: High Drag States and Mixing  

Science Conference Proceedings (OSTI)

A three-dimensional large-eddy simulation (LES) model was used to examine how stratified flow interacts with bottom obstacles in the coastal ocean. Bottom terrain representing a 2D ridge was modeled using a finite-volume approach with ridge ...

Eric D. Skyllingstad; Hemantha W. Wijesekera

2004-01-01T23:59:59.000Z

51

Evaluation of numerical strategies for large eddy simulation of particulate two-phase recirculating flows  

Science Conference Proceedings (OSTI)

Predicting particle dispersion in recirculating two-phase flows is a key issue for reacting flows and a potential application of large eddy simulation (LES) methods. In this study, Euler/Euler and Euler/Lagrange LES approaches are compared in the bluff ... Keywords: Euler/Euler, Euler/Lagrange, LES, Particles, Two-phase recirculating flows

E. Riber; V. Moureau; M. Garca; T. Poinsot; O. Simonin

2009-01-01T23:59:59.000Z

52

A Large-Eddy Simulation Study of Thermal Effects on Turbulence Coherent Structures in and above a Building Array  

Science Conference Proceedings (OSTI)

Thermal effects on turbulent flow in and above a cubical building array are numerically investigated using the parallelized large-eddy simulation model (PALM). Two cases (no heating and bottom heating) are simulated and are compared with each ...

Seung-Bu Park; Jong-Jin Baik

2013-06-01T23:59:59.000Z

53

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

Science Conference Proceedings (OSTI)

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

Craig M. Smith; Eric D. Skyllingstad

2009-10-01T23:59:59.000Z

54

A Large-Eddy Simulation Study of Bottom Heating Effects on Scalar Dispersion in and above a Cubical Building Array  

Science Conference Proceedings (OSTI)

Thermal effects on scalar dispersion in and above a cubical building array are numerically investigated using the parallelized large-eddy simulation model (PALM). Two cases (no heating and bottom heating) are simulated, and scalar dispersion ...

Seung-Bu Park; Jong-Jin Baik; Young-Hee Ryu

55

Turbulence Structure and Implications for Dispersion: Insights from Large-Eddy Simulations  

SciTech Connect

We have presented two flows where detailed knowledge of the fluid mechanics would appear to be crucial for accurate dispersion modeling. We expect that Large-eddy simulations (LES) will complement traditional dispersion modeling by providing both the ability to discern between cases where traditional models work well and cases where more complicated characterizations are necessary, and a method to investigate potentially unique flow features and turbulence structure for specific flow problems.

Calhoun, R; Cederwall, R; Street, R

1999-10-04T23:59:59.000Z

56

The Effect of Mesh Resolution on Convective Boundary Layer Statistics and Structures Generated by Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

A massively parallel large-eddy simulation (LES) code for planetary boundary layers (PBLs) that utilizes pseudospectral differencing in horizontal planes and solves an elliptic pressure equation is described. As an application, this code is used ...

Peter P. Sullivan; Edward G. Patton

2011-10-01T23:59:59.000Z

57

A Fast Three-Dimensional Approximation for the Calculation of Surface Irradiance in Large-Eddy Simulation Models  

Science Conference Proceedings (OSTI)

Cloud-resolving modelsin particular, large-eddy simulation (LES) modelsare important tools to improve the understanding of cloudradiation interactions. A method is presented for accurate, yet fast, three-dimensional calculation of surface ...

Kathrin Wapler; Bernhard Mayer

2008-12-01T23:59:59.000Z

58

A Large-Eddy Simulation Study of Thermal Effects on Turbulent Flow and Dispersion in and above a Street Canyon  

Science Conference Proceedings (OSTI)

Thermal effects on turbulent flow and dispersion in and above an idealized street canyon with a street aspect ratio of 1 are numerically investigated using the parallelized large-eddy simulation model (PALM). Each of upwind building wall, street ...

Seung-Bu Park; Jong-Jin Baik; Siegfried Raasch; Marcus Oliver Letzel

2012-05-01T23:59:59.000Z

59

Impact of Surface Flux Formulations and Geostrophic Forcing on Large-Eddy Simulations of Diurnal Atmospheric Boundary Layer Flow  

Science Conference Proceedings (OSTI)

The impact of surface flux boundary conditions and geostrophic forcing on multiday evolution of flow in the atmospheric boundary layer (ABL) was assessed using large-eddy simulations (LES). The LES investigations included several combinations of ...

Vijayant Kumar; Gunilla Svensson; A. A. M. Holtslag; Charles Meneveau; Marc B. Parlange

2010-07-01T23:59:59.000Z

60

Application of a Perturbation Recycling Method in the Large-Eddy Simulation of a Mesoscale Convective Internal Boundary Layer  

Science Conference Proceedings (OSTI)

An arrangement of boundary conditions is described and demonstrated that facilitates the large-eddy simulation (LES) of inhomogeneous boundary layers such as internal boundary layers. In addition to the domain where the internal boundary layer ...

Shane D. Mayor; Philippe R. Spalart; Gregory J. Tripoli

2002-08-01T23:59:59.000Z

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


61

Convective Entrainment into a Shear-Free, Linearly Stratified Atmosphere: Bulk Models Reevaluated through Large Eddy Simulations  

Science Conference Proceedings (OSTI)

Relationships between parameters of convective entrainment into a shear-free, linearly stratified atmosphere predicted by the zero-order jump and general-structure bulk models of entrainment are reexamined using data from large eddy simulations (...

Evgeni Fedorovich; Robert Conzemius; Dmitrii Mironov

2004-02-01T23:59:59.000Z

62

Evaluation of Turbulence Closure Models for Large-Eddy Simulation over Complex Terrain: Flow over Askervein Hill  

Science Conference Proceedings (OSTI)

The evaluation of turbulence closure models for large-eddy simulation (LES) has primarily been performed over flat terrain, where comparisons with theory and observations are simplified. The authors have previously developed improved closure ...

Fotini Katopodes Chow; Robert L. Street

2009-05-01T23:59:59.000Z

63

Analysis of the planetary boundary layer with a database of large-eddy simulation experiments  

E-Print Network (OSTI)

Observational studies of a planetary boundary layer (PBL) are difficult. Ground-born measurements usually characterize only a small portion of the PBL immediately above the surface. Air-born measurements cannot be obtained close to the surface and therefore cannot capture any significant portion of the PBL interior. Moreover, observations are limited in choice of instrumentation, time, duration, location of measurements and occasional weather conditions. Although turbulence-resolving simulations with a large-eddy simulation (LES) code do not supplant observational studies, they provide valuable complementary information on different aspect of the PBL dynamics, which otherwise difficult to acquire. These circumstances motivated development of a medium-resolution database (DATABASE64) of turbulence-resolving simulations, which is available on ftp://ftp.nersc.no/igor/. DATABASE64 covers a range of physical parameters typical for the barotropic SBL over a homogeneous rough surface. LES runs in DATABASE64 simulate...

Esau, Igor

2010-01-01T23:59:59.000Z

64

Large eddy simulation models for incompressible magnetohydrodynamics derived from the variational multiscale formulation  

Science Conference Proceedings (OSTI)

Novel large eddy simulation (LES) models are developed for incompressible magnetohydrodynamics (MHD). These models include the application of the variational multiscale formulation of LES to the equations of incompressible MHD. Additionally, a new residual-based eddy viscosity model is introduced for MHD. A mixed LES model that combines the strengths of both of these models is also derived. The new models result in a consistent numerical method that is relatively simple to implement. The need for a dynamic procedure in determining model coefficients is no longer required. The new LES models are tested on a decaying Taylor-Green vortex generalized to MHD and benchmarked against classical LES turbulence models. The LES simulations are run in a periodic box of size [-{pi}, {pi}]{sup 3} with 32 modes in each direction and are compared to a direct numerical simulation (DNS) with 512 modes in each direction. The new models are able to account for the essential MHD physics which is demonstrated via comparisons of energy spectra. We also compare the performance of our models to a DNS simulation by Pouquet et al.['The dynamics of unforced turbulence at high Reynolds number for Taylor-Green vortices generalized to MHD,' Geophys. Astrophys. Fluid Dyn. 104, 115-134 (2010)], for which the ratio of DNS modes to LES modes is 262:144.

Sondak, David; Oberai, Assad A. [Rensselaer Polytechnic Institute, SCOREC, CII 4225, 110 8th Street, Troy, New York 12180 (United States)

2012-10-15T23:59:59.000Z

65

Approximate deconvolution large eddy simulation of a barotropic ocean circulation model  

E-Print Network (OSTI)

This paper puts forth a new large eddy simulation closure modeling strategy for two-dimensional turbulent geophysical flows. This closure modeling approach utilizes approximate deconvolution, which is based solely on mathematical approximations and does not employ phenomenological arguments, such as the concept of an energy cascade. The new approximate deconvolution model is tested in the numerical simulation of the wind-driven circulation in a shallow ocean basin, a standard prototype of more realistic ocean dynamics. The model employs the barotropic vorticity equation driven by a symmetric double-gyre wind forcing, which yields a four-gyre circulation in the time mean. The approximate deconvolution model yields the correct four-gyre circulation structure predicted by a direct numerical simulation, on a much coarser mesh but at a fraction of the computational cost. This first step in the numerical assessment of the new model shows that approximate deconvolution could represent a viable alternative to standar...

San, Omer; Wang, Zhu; Iliescu, Traian

2011-01-01T23:59:59.000Z

66

Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor  

E-Print Network (OSTI)

The average and fluctuating components in a model ring-type gas turbine combustor are characterized using a Large Eddy Simulation at a Reynolds number of 11,000, based on the bulk velocity and the mean channel height. A spatial filter is applied to the incompressible Navier-Stokes equations, and a high pass filtered Smagorinsky model is used to model the sub-grid scales. Two cases are studied: one with only the swirler inlet active, and one with a single row of dilution jets activated, operating at a momentum flux ratio J of 100. The goal of both of these studies is to validate the capabilities of the solver NEK5000 to resolve important flow features inherent to gas turbine combustors by comparing qualitatively to the work of Jakirlic. Both cases show strong evidence of the Precessing Vortex Core, an essential flow feature in gas turbine combustors. Each case captures other important flow characteristics, such as corner eddies, and in general predicts bulk flow movements well. However, the simulations performed quite poorly in terms of predicting turbulence shear stress quantities. Difficulties in properly emulating the turbulent velocity entering the combustor for the swirl, as well as mesh quality concerns, may have skewed the results. Overall, though small length scale quantities were not accurately captured, the large scale quantities were, and this stress test on the HPF LES model will be built upon in future work that looks at more complex combustors.

Camp, Joshua Lane

2011-05-01T23:59:59.000Z

67

Large-eddy simulations of Richtmyer-Meshkov instability in a converging geometry  

E-Print Network (OSTI)

The Richtmyer-Meshkov instability (RMI) refers to the baroclinic generation of vorticity at a perturbed density interface when impacted by a shock wave. It is often thought of as the impulsive limit of the Rayleigh-Taylor instability (RTI). The fluid dynamics video "large-eddy simulations (LES) of RMI in a converging geometry" shows the mixing of materials resulting from the interaction of an imploding cylindrical shock wave with a concentric perturbed interface that separates outside light gas from heavy gas (initially 5 times denser) inside a wedge. At the initial impact, the incident shock Mach number is either 1.3 or 2.0. The present canonical simulations support recent interests on compressible turbulent mixing in converging geometries relevant to both inertial confinement fusion and core-collapse supernovae dynamics.

Lombardini, Manuel

2009-01-01T23:59:59.000Z

68

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. DAsaro

2008-07-01T23:59:59.000Z

69

The Behavior of Passive and Buoyant Plumes in a Convective Boundary Layer, as Simulated with a Large-Eddy Model  

Science Conference Proceedings (OSTI)

With a large-eddy model the large-scale flow structure of the convective boundary layer is simulated in a box of (5 5 2) km. The calculation is run till the turbulence has reached a quasi-steady state. At that time we introduce a line-source ...

L. van Haren; F. T. M. Nieuwstadt

1989-09-01T23:59:59.000Z

70

Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study  

Science Conference Proceedings (OSTI)

The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (...

Alessandro Dosio; Jordi Vil-Guerau de Arellano

2006-04-01T23:59:59.000Z

71

Influences on the Height of the Stable Boundary Layer as seen in Large-Eddy Simulations  

DOE Green Energy (OSTI)

Numerical weather prediction (NWP) models and atmospheric dispersion models rely on parameterizations of planetary boundary layer height. In the case of a stable boundary layer, errors in boundary layer height estimation can result in gross errors in boundary-layer evolution and in prediction of turbulent mixing within the boundary layer. We use large-eddy simulations (LES) of moderately stable boundary layers to characterize the effects of various physical processes on stable boundary layers. The stable boundary layer height is assumed to be a function of surface friction velocity, geostrophic wind, Monin-Obukhov length, and the strength of the temperature inversion atop the stable boundary layer. This temperature inversion induces gravity waves with a frequency determined by the strength of the temperature inversion.

Kosovic, B; Lundquist, J K

2004-03-29T23:59:59.000Z

72

Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors  

E-Print Network (OSTI)

The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3x3 and 5x5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the single-phase incompressible Navier-Stokes equations. The simulations explicitly resolve the la...

Bakosi, J; Lowrie, R B; Pritchett-Sheats, L A; Nourgaliev, R R

2013-01-01T23:59:59.000Z

73

A low numerical dissipation patch-based adaptive mesh refinement method for large-eddy simulation of compressible flows  

Science Conference Proceedings (OSTI)

We present a methodology for the large-eddy simulation of compressible flows with a low-numerical dissipation scheme and structured adaptive mesh refinement (SAMR). A description of a conservative, flux-based hybrid numerical method that uses both centered ... Keywords: Compressible flow, LES, Numerical methods, SAMR, Turbulence

C. Pantano; R. Deiterding; D. J. Hill; D. I. Pullin

2007-01-01T23:59:59.000Z

74

Large-eddy simulations of air flow and turbulence within and around low aspect ratio cylindrical open-top chambers  

Science Conference Proceedings (OSTI)

The flow around cylindrical open-top chambers (OTCs) with aspect ratios (i.e., height-to-diameter ratios) much less than unity is investigated using a large-eddy simulation (LES) model. The solid structures are represented using the immersed ...

Philip Cunningham; Rodman R. Linn; Eunmo Koo; Cathy J. Wilson

75

Examining Two-Way Grid Nesting for Large Eddy Simulation of the PBL Using the WRF Model  

Science Conference Proceedings (OSTI)

The performance of two-way nesting for large eddy simulation (LES) of PBL turbulence is investigated using the Weather Research and Forecasting model framework. A pair of LES-within-LES experiments are performed where a finer-grid LES covering a ...

C-H. Moeng; Jimy Dudhia; Joe Klemp; Peter Sullivan

2007-06-01T23:59:59.000Z

76

Quasi-Lagrangian Large Eddy Simulations of Cross-Equatorial Flow in the East Pacific Atmospheric Boundary Layer  

Science Conference Proceedings (OSTI)

Using a large eddy simulation (LES), the atmospheric boundary layer (ABL) is numerically modeled along 95W from 8S to 4N during boreal autumn, and compared to observations from the East Pacific Investigation of Climate Processes in the Coupled ...

S. P. de Szoeke; C. S. Bretherton

2004-08-01T23:59:59.000Z

77

Transition and Equilibration of Neutral Atmospheric Boundary Layer Flow in One-Way Nested Large-Eddy Simulations Using the Weather Research and Forecasting Model  

Science Conference Proceedings (OSTI)

The Weather Research and Forecasting Model permits finescale large-eddy simulations (LES) to be nested within coarser simulations, an approach that can generate more accurate turbulence statistics and improve other aspects of simulated flows. ...

Jeff Mirocha; Gokhan Kirkil; Elie Bou-Zeid; Fotini Katopodes Chow; Branko Kosovi?

2013-03-01T23:59:59.000Z

78

Bulk Models of the Sheared Convective Boundary Layer: Evaluation through Large Eddy Simulations  

Science Conference Proceedings (OSTI)

A set of first-order model (FOM) equations, describing the sheared convective boundary layer (CBL) evolution, is derived. The model output is compared with predictions of the zero-order bulk model (ZOM) for the same CBL type. Large eddy ...

Robert Conzemius; Evgeni Fedorovich

2007-03-01T23:59:59.000Z

79

Large-Eddy Boundary Layer Entrainment  

Science Conference Proceedings (OSTI)

A series of large-eddy simulations have been performed to explore boundary layer entrainment under conditions of a strongly capped inversion layer with the boundary layer dynamics driven dominantly by buoyant forcing. Different conditions ...

D. C. Lewellen; W. S. Lewellen

1998-08-01T23:59:59.000Z

80

A Large-Eddy Simulation Study of Bottom-Heating Effects on Scalar Dispersion in and above a Cubical Building Array  

Science Conference Proceedings (OSTI)

Thermal effects on scalar dispersion in and above a cubical building array are numerically investigated using the parallelized large-eddy simulation model (PALM). Two cases (no heating and bottom heating) are simulated, and scalar dispersion ...

Seung-Bu Park; Jong-Jin Baik; Young-Hee Ryu

2013-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

High-Resolution Large-Eddy Simulations of Flow in a Steep Alpine Valley. Part I: Methodology, Verification, and Sensitivity Experiments  

Science Conference Proceedings (OSTI)

This paper investigates the steps necessary to achieve accurate simulations of flow over steep, mountainous terrain. Large-eddy simulations of flow in the Riviera Valley in the southern Swiss Alps are performed at horizontal resolutions as fine ...

Fotini Katopodes Chow; Andreas P. Weigel; Robert L. Street; Mathias W. Rotach; Ming Xue

2006-01-01T23:59:59.000Z

82

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

Science Conference Proceedings (OSTI)

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

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

2009-06-01T23:59:59.000Z

83

Monin-Obukhov similarity functions for the structure parameters of temperature and humidity in the unstable surface layer: results from high-resolution large-eddy simulations  

Science Conference Proceedings (OSTI)

Large-eddy simulations (LES) of free convective to near-neutral boundary layers are used to investigate the surface layer turbulence. The article focuses on the Monin-Obukhov similarity theory (MOST) relationships that relate the structure ...

Bjrn Maronga

84

Effects Caused by Varying the Strength of the Capping Inversion Based on a Large Eddy Simulation Model of the Shear-Free Convective Boundary Layer  

Science Conference Proceedings (OSTI)

Effects caused by variation of the potential temperature lapse rate ? in the free atmosphere are examined based on a large eddy simulation model of the shear-free convective atmospheric boundary layer. The obtained results show that only near ...

Zbigniew Sorbjan

1996-07-01T23:59:59.000Z

85

Responses of Shallow Cumulus Convection to Large-Scale Temperature and Moisture Perturbations: A Comparison of Large-Eddy Simulations and a Convective Parameterization Based on Stochastically Entraining Parcels  

Science Conference Proceedings (OSTI)

Responses of shallow cumuli to large-scale temperature/moisture perturbations are examined through diagnostics of large-eddy simulations (LESs) of the undisturbed Barbados Oceanographic and Meteorological Experiment (BOMEX) case and a stochastic ...

Ji Nie; Zhiming Kuang

2012-06-01T23:59:59.000Z

86

Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint  

DOE Green Energy (OSTI)

This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modelling, and the examination of more array configurations.

Churchfield, M. J.; Li, Y.; Moriarty, P. J.

2012-07-01T23:59:59.000Z

87

Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint  

DOE Green Energy (OSTI)

This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used to determine the inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modeling, and the examination of more array configurations.

Churchfield, M. J.; Li, Y.; Moriarty, P. J.

2011-07-01T23:59:59.000Z

88

Large-Eddy Simulation of Flow and Pollutant Transport in Street Canyons of Different Building-Height-to-Street-Width Ratios  

Science Conference Proceedings (OSTI)

This study employs a large-eddy simulation technique to investigate the flow, turbulence structure, and pollutant transport in street canyons of building-height-to-street-width (aspect) ratios of 0.5, 1.0, and 2.0 at a Reynolds number of 12 000 ...

Chun-Ho Liu; Mary C. Barth; Dennis Y. C. Leung

2004-10-01T23:59:59.000Z

89

Large-Eddy Simulations of Air Flow and Turbulence within and around Low-Aspect-Ratio Cylindrical Open-Top Chambers  

Science Conference Proceedings (OSTI)

The flow around cylindrical open-top chambers (OTCs) with aspect ratios (i.e., height-to-diameter ratios) much less than unity is investigated using a large-eddy simulation (LES) model. The solid structures are represented using the immersed ...

Philip Cunningham; Rodman R. Linn; Eunmo Koo; Cathy J. Wilson

2013-08-01T23:59:59.000Z

90

Visualization and analysis of eddies in a global ocean simulation  

SciTech Connect

Eddies at a scale of approximately one hundred kilometers have been shown to be surprisingly important to understanding large-scale transport of heat and nutrients in the ocean. Due to difficulties in observing the ocean directly, the behavior of eddies below the surface is not very well understood. To fill this gap, we employ a high-resolution simulation of the ocean developed at Los Alamos National Laboratory. Using large-scale parallel visualization and analysis tools, we produce three-dimensional images of ocean eddies, and also generate a census of eddy distribution and shape averaged over multiple simulation time steps, resulting in a world map of eddy characteristics. As expected from observational studies, our census reveals a higher concentration of eddies at the mid-latitudes than the equator. Our analysis further shows that mid-latitude eddies are thicker, within a range of 1000-2000m, while equatorial eddies are less than 100m thick.

Williams, Sean J [Los Alamos National Laboratory; Hecht, Matthew W [Los Alamos National Laboratory; Petersen, Mark [Los Alamos National Laboratory; Strelitz, Richard [Los Alamos National Laboratory; Maltrud, Mathew E [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Hlawitschka, Mario [UC DAVIS; Hamann, Bernd [UC DAVIS

2010-10-15T23:59:59.000Z

91

Nested Mesoscale Large-Eddy Simulations with WRF: Performance in Real Test Cases  

Science Conference Proceedings (OSTI)

This paper assesses the performance of the Weather Research and Forecasting Model (WRF) as a tool for multiscale atmospheric simulations. Tests are performed in real and idealized cases with multiple configurations and with resolutions ranging ...

Charles Talbot; Elie Bou-Zeid; Jim Smith

2012-10-01T23:59:59.000Z

92

Consequences of the Large-Scale Subsidence Rate on the Stably Stratified Atmospheric Boundary Layer Over the Arctic Ocean, as seen in Large-Eddy Simulations  

Science Conference Proceedings (OSTI)

The analysis of surface heat fluxes and sounding profiles from SHEBA indicated possible significant effects of subsidence on the structure of stably-stratified ABLs (Mirocha et al. 2005). In this study the influence of the large-scale subsidence rate on the stably stratified atmospheric boundary layer (ABL) over the Arctic Ocean during clear sky, winter conditions is investigated using a large-eddy simulation model. Simulations are conducted while varying the subsidence rate between 0, 0.001 and 0.002 ms{sup -1}, and the resulting quasi-equilibrium ABL structure and evolution are examined. Simulations conducted without subsidence yield ABLs that are deeper, more strongly mixed, and cool much more rapidly than were observed. The addition of a small subsidence rate significantly improves agreement between the simulations and observations regarding the ABL height, potential temperature profiles and bulk heating rates. Subsidence likewise alters the shapes of the surface-layer flux, stress and shear profiles, resulting in increased vertical transport of heat while decreasing vertical momentum transport. A brief discussion of the relevance of these results to parameterization of the stable ABL under subsiding conditions in large-scale numerical weather and climate prediction models is presented.

Mirocha, J D; Kosovic, B

2006-01-19T23:59:59.000Z

93

Large Eddy Simulations and stereoscopic particle image velocimetry measurements in a scraped heat exchanger crystallizer  

E-Print Network (OSTI)

*Corresponding author: M.Rodriguez@tudelft.nl Abstract The transport phenomena in scraped heat exchanger crystallizers are critical for the process performance. Fluid flow and turbulence close to the heat exchanger with a focus on the bottom region where the heat exchanging surface was located. The simulations were validated

Paris-Sud XI, Université de

94

Q. J. R. Meteorol. Soc. (2006), 132, pp. 16931715 doi: 10.1256/qj.05.145 Evaluation of a large-eddy model simulation of a mixed-phase altocumulus  

E-Print Network (OSTI)

of mixed-phase clouds, the case shows the importance of using: (i) separate prognostic ice and liquid water-eddy model simulation of a mixed-phase altocumulus cloud using microwave radiometer, lidar and Doppler radar February 2006) SUMMARY Using the Met Office large-eddy model (LEM) we simulate a mixed-phase altocumulus

Hogan, Robin

95

LES Model Sensitivities to Domains, Grids, and Large-Eddy Timescales  

Science Conference Proceedings (OSTI)

This study has addressed the sensitivity of large-eddy simulation (LES) models to domain size, grid resolution, and the number of large-eddy turnover times (t) of integration, and their respective effects on the characteristic turbulence ...

Ernest Agee; Alexander Gluhovsky

1999-02-01T23:59:59.000Z

96

A Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint  

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

Large-Eddy Simulation Study Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal- Current Turbines Preprint M.J. Churchfield, Y. Li, and P.J. Moriarty To be presented at the 9 th European Wave and Tidal Energy Conference 2011 Southhampton, England September 4 - 9, 2011 Conference Paper NREL/CP-5000-51765 July 2011 NOTICE The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC (Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. Accordingly, the US Government and Alliance retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. This report was prepared as an account of work sponsored by an agency of the United States government.

97

Implementation and assessment of turbine wake models in the Weather Research and Forecasting model for both mesoscale and large-eddy simulation  

SciTech Connect

Flow dynamics in large wind projects are influenced by the turbines located within. The turbine wakes, regions characterized by lower wind speeds and higher levels of turbulence than the surrounding free stream flow, can extend several rotor diameters downstream, and may meander and widen with increasing distance from the turbine. Turbine wakes can also reduce the power generated by downstream turbines and accelerate fatigue and damage to turbine components. An improved understanding of wake formation and transport within wind parks is essential for maximizing power output and increasing turbine lifespan. Moreover, the influence of wakes from large wind projects on neighboring wind farms, agricultural activities, and local climate are all areas of concern that can likewise be addressed by wake modeling. This work describes the formulation and application of an actuator disk model for studying flow dynamics of both individual turbines and arrays of turbines within wind projects. The actuator disk model is implemented in the Weather Research and Forecasting (WRF) model, which is an open-source atmospheric simulation code applicable to a wide range of scales, from mesoscale to large-eddy simulation. Preliminary results demonstrate the applicability of the actuator disk model within WRF to a moderately high-resolution large-eddy simulation study of a small array of turbines.

Singer, M; Mirocha, J; Lundquist, J; Cleve, J

2010-03-03T23:59:59.000Z

98

Numerical Simulation of Mesoscale Eddies over Melbourne  

Science Conference Proceedings (OSTI)

A mesoscale wind field model is used to simulate a cyclonic nocturnal eddy which may form over Melbourne under stable conditions with light synoptic winds. Two types of eddy (Mel-I and Mel-II) are identified, with separate formation mechanisms. ...

John L. McGregor; Fujio Kimura

1989-01-01T23:59:59.000Z

99

Multiscale Large Eddy States in Weakly Stratified Planetary Boundary Layers  

Science Conference Proceedings (OSTI)

We first discuss observations of two classes of two-dimensional large eddy states in weakly stratified atmospheric boundary layers. One class is characterized by large eddies with a single horizontal scale. The other contains multiscale large ...

Pierre D. Mourad; Robert A. Brown

1990-02-01T23:59:59.000Z

100

High-Resolution Large-Eddy Simulations of Scalar Transport in Atmospheric Boundary Layer Flow over Complex Terrain  

Science Conference Proceedings (OSTI)

This paper presents high-resolution numerical simulations of the atmospheric flow and concentration fields accompanying scalar transport and diffusion from a point source in complex terrain. Scalar dispersion is affected not only by mean flow, ...

Takenobu Michioka; Fotini Katopodes Chow

2008-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

The Effects of Nonhomogeneous Surface Fluxes on the Convective Boundary Layer: A Case Study Using Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

Most land surfaces are quasi-randomly nonhomogeneous, yet most boundary-layer studies assume homogeneous or simply varying surface conditions. In this study, nonhomogeneous surface fluxes of realistic scale and amplitude are applied to a large-...

Leslie M. Hechtel; Roland B. Stul; Chin-Hoh Moeng

1990-07-01T23:59:59.000Z

102

A Large-Eddy Simulation Study of the Influence of Subsidence on the Stably Stratified Atmospheric Boundary Layer  

E-Print Network (OSTI)

Study of the In?uence of Subsidence on the Stably Strati?eduence of the large-scale subsidence rate, S, on the stablydepth and temperature. Subsidence reduces the magnitudes of

Mirocha, Jeffrey D.; Kosovi?, Branko

2010-01-01T23:59:59.000Z

103

Researchers at the National Renewable Energy Laboratory (NREL) develop a high-fidelity large-eddy simulation model  

E-Print Network (OSTI)

than current models. As the market for wind energy grows, wind turbines and wind plants are becoming wind plants, reduce the cost of wind energy, and save wind plant developers millions of dollars in lostResearchers at the National Renewable Energy Laboratory (NREL) develop a high-fidelity large

104

Large Eddy Simulations of extinction  

E-Print Network (OSTI)

-speed camera images from an experiment. Using model constants previously calibrated against pilot jet flame with localised extinction, we obtain that at the experimentally determined blow-off velocity, the predicted flame also blows-off, demonstrating... , Qh = h|?, takes the form: ?Qh ?t + uj|? ?Qh ?xj = eh + N |? ?2Qh ??2 + ?h|? ? ( Qh + (1? ?) ?Qh ?? ) ?|? (2) where the radiation and pressure work terms have been neglected. The terms e? and eh in Eq. (1) and Eq. (2) represent contributions from...

Ayache, S; Garmory, A; Tyliszczak, A; Mastorakos, E

2012-08-29T23:59:59.000Z

105

Microphysical Structure of the Marine Boundary Layer under Strong Wind and Spray Formation as Seen from Simulations Using a 2D Explicit Microphysical Model. Part I: The Impact of Large Eddies  

Science Conference Proceedings (OSTI)

The effects of large eddies (LE) on the marine boundary layer (MBL) microphysics and thermodynamics is investigated using a 2D Lagrangian model with spectral bin microphysics including effects of sea spray. The 600 m 400 m MBL computational area ...

J. Shpund; M. Pinsky; A. Khain

2011-10-01T23:59:59.000Z

106

Simulation and Prediction of the Catalina Eddy  

Science Conference Proceedings (OSTI)

Observational studies generally suggest that the formation of the Catalina Eddy in the bight of southern California results from interaction between the synoptic-scale northerly flow and the topographic barrier along the southern California ...

Kyozo Ueyoshi; John O. Roads

1993-11-01T23:59:59.000Z

107

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

E-Print Network (OSTI)

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

Wang, Yao; Manuel, Lance

2013-01-01T23:59:59.000Z

108

On the Application of the Dynamic Smagorinsky Model to Large-Eddy Simulations of the Cloud-Topped Atmospheric Boundary Layer  

Science Conference Proceedings (OSTI)

In this paper the dynamic Smagorinsky model originally developed for engineering flows is adapted for simulations of the cloud-topped atmospheric boundary layer in which an anelastic form of the governing equations is used. The adapted model ...

M. P. Kirkpatrick; A. S. Ackerman; D. E. Stevens; N. N. Mansour

2006-02-01T23:59:59.000Z

109

Evaluation of Scalar Advection Schemes in the Advanced Research WRF Model Using Large-Eddy Simulations of AerosolCloud Interactions  

Science Conference Proceedings (OSTI)

In the Advanced Research Weather Research and Forecasting Model (ARW), versions 3.0 and earlier, advection of scalars was performed using the RungeKutta time-integration scheme with an option of using a positive-definite (PD) flux limiter. Large-...

Hailong Wang; William C. Skamarock; Graham Feingold

2009-08-01T23:59:59.000Z

110

Horizontal Entrainment and Detrainment in Large-Scale Eddies  

Science Conference Proceedings (OSTI)

We compute the evolution of disturbances on a circularly symmetric eddy having uniform vorticity in a central core, in a surrounding annulus, and in the irrotational exterior water mass. This vortex is known to be (Kelvin-Helmholtz) unstable when ...

Melvin E. Stern

1987-10-01T23:59:59.000Z

111

Some Correlations between the Large-Scale Meridional Eddy Momentum Transport and Zonal Mean Quantities  

Science Conference Proceedings (OSTI)

An empirical study has been made which compares the large-scale meridional eddy momentum transport with some selected zonal mean quantities by calculating correlations between them as a function of time lag and latitude. The basic dataset was the ...

Anne Leach

1984-01-01T23:59:59.000Z

112

Large-Scale Vertical Eddy Diffusion in the Main Pycnocline of the Central North Pacific  

Science Conference Proceedings (OSTI)

Indirect procedures are used to estimate the latitudinal distribution of the large-scale vertical eddy diffusivity coefficient in the main pycnocline from the interannual change in T?, ?? structure of the water column in the central midlatitude ...

Warren White; Robert Bernstein

1981-04-01T23:59:59.000Z

113

Simulation for the assessment of wall thinning using eddy current method  

Science Conference Proceedings (OSTI)

A pipe with protective cladding and insulation was simplified to a four-layered structure when the diameter of a pipe is large enough, and analytical solutions for sinusoidal and pulsed wave excitation were derived. Simulation implemented by using the analytical solutions showed that sinusoidal excitation is not appropriate for the monitoring of inner thinning, while pulsed eddy current method can be used to measure wall-thickness regardless of inner or outer thinning by using the decay rate of log(Bz) as a particular parameter to evaluate wall thickness.

Cheng, W.; Komura, I. [NDE Center, Japan Power Engineering and Inspection Corporation, Yokohama 230-0044 (Japan)

2011-06-23T23:59:59.000Z

114

A Monte Carlo Simulation of the Eddy Accumulation Method for Measuring Scalar Fluxes  

Science Conference Proceedings (OSTI)

A numerical simulation of the eddy accumulation technique for measuring scalar fluxes has been devised using pseudo-random number pairs generated by computer. Input information is the joint probability density function of the vertical velocity ...

Edward E. O'Brien

1985-03-01T23:59:59.000Z

115

A Simulation of the January Standing Wave Pattern Including the Effects of Transient Eddies  

Science Conference Proceedings (OSTI)

A steady-state, linear, two-level primitive equation model is used to simulate the January standing wave pattern as a response to mountain, diabatic and transient eddy effects. The model equations are linearized around an observed zonal mean ...

J. D. Opsteegh; A. D. Vernekar

1982-04-01T23:59:59.000Z

116

The Conservation of Potential vorticity along Lagrangian Trajectories in Simulations of Eddy-Driven Flows  

Science Conference Proceedings (OSTI)

The purpose of this note is to investigate the use of Lagrangian potential vorticity conservation as a numerically independent method for checking a posteriori the dynamical consistency of an eddy-resolving GCM simulation. This is performed for a ...

Bach Lien Hua

1994-02-01T23:59:59.000Z

117

The Roles of Mean Meridional Motions and Large-Scale Eddies in Zonally Averaged Circulations  

Science Conference Proceedings (OSTI)

A hierarchy of zonally averaged atmospheric models is used to study the role of mean meridional motions and large-scale eddies in determining the zonal climate. Five models are developed: a radiative-convective equilibrium model (no large-scale ...

Karl E. Taylor

1980-01-01T23:59:59.000Z

118

Generation and Separation of Mesoscale Eddies from Surface Ocean Fronts  

Science Conference Proceedings (OSTI)

This study is motivated by Arctic Ocean observations of sub-mixed layer eddies found at large distances from their assumed formation region of a surface ocean front. We explore eddy formation through high resolution numerical simulations of ...

Georgy E. Manucharyan; Mary-Louise Timmermans

119

Adaptive Detached Eddy Simulation of a Vertical Tail with Active Flow  

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

Adaptive Detached Eddy Simulation of a Vertical Tail with Active Flow Control Adaptive Detached Eddy Simulation of a Vertical Tail with Active Flow Control Adaptive Detached Eddy Simulation of a Vertical Tail with Active Flow Control PI Name: Kenneth Jansen PI Email: jansenke@colorado.edu Institution: University of Colorado Allocation Program: INCITE Allocation Hours at ALCF: 40 Million Year: 2012 Research Domain: Engineering The use of fuel-and its accompanying costs-has become an increasing concern in many industries. Researchers are examining the issue of fuel reduction in commercial jet aircraft from the perspective of redesign. By redesigning the vertical tail of a commercial jet, they hope to reduce jet fuel use by 0.5%, resulting in annual savings of $300 million. Using -synthetic commercial jet aircraft, the team will perform a series

120

Large eddy simultations of the atmospheric boundary layer east of the Colorado Rockies  

SciTech Connect

Large eddy simulation, LES, has often been carried out for the idealized situation of a simple convective boundary layer. Studies of dual Doppler radar and aircraft data from the Phoenix II experiment indicate that the boundary layer of the Colorado High Plains is not a purely convective boundary layer and it is influenced by the mountains to the west. The purpose of this study is to investigate the atmospheric boundary layer on one particular day on the Colorado High Plains. This research applies a LES nested within larger grids, which contain realistic topography and can simulate the larger-scale circulations initiated by the presence of the mountain barrier. How and to what extent the atmospheric boundary layer of the Colorado High Plains is influenced by larger scale circulations and other phenomena associated with the mountain barrier to the west is investigated. The nested grid LES reproduces the characteristics of the atmosphere for the case study day reasonably well. The mountains influence the atmospheric boundary layer over the plains to the east in several ways. The mountains contribute to the vertical shear of the horizontal winds through the thermally-induced mountain-plains circulation. As a consequence of the wind shear, the boundary layer that develops over the mountains is advected eastward over the top of the plains boundary layer, which is developing separately. This layer is marked by a mixture of gravity waves and turbulence and is atypical of a purely convective boundary layer. Just below this layer, the capping inversion of the plains boundary layer is weak and poorly defined compared to the inversions capping purely convective boundary layers. Gravity waves, triggered by the obstacle of the Rocky Mountains and by convection in the mountain boundary layer, also influence the atmosphere above the Colorado High Plains. These influences are found to have significant effects on the turbulence statistics and the energy spectra.

Costigan, K.R.; Cotton, W.R.

1992-10-22T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Dynamic Network Forecasting using SimGrid Simulations Matthieu Imbert and Eddy Caron  

E-Print Network (OSTI)

exists. Currently, the most widely-used approach for data management for distributed grid computation capacities, the network equipment capacities (line-cards or back-plane capacity), the interactions bothDynamic Network Forecasting using SimGrid Simulations Matthieu Imbert and Eddy Caron Université de

122

The Simulation of Stationary and Transient Geopotential-Height Eddies in January and July with a Spectral General Circulation Model  

Science Conference Proceedings (OSTI)

We examine the characteristics of stationary and transient eddies in the geopotential-height field as simulated by a spectral general circulation model. The model possesses a realistic distribution of continents and oceans and realistic, but ...

Robert C. Malone; Eric J. Pitcher; Maurice L. Blackmon; Kamal Puri; William Bourke

1984-04-01T23:59:59.000Z

123

Towards large eddy simulations of flame extinction and ...  

Science Conference Proceedings (OSTI)

... products of incomplete combustion (carbon monoxide, unburnt hydro- carbons, hydrogen ... to play a role in the net emission of car- bon monoxide ...

2007-10-03T23:59:59.000Z

124

Cooling of Entrained Parcels in a Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

The relative importance, for cloud-top entrainment, of the cooling rates due to longwave radiation, evaporation, and mixing was assessed through analysis of the results produced by a Lagrangian parcel-tracking model (LPTM) incorporated into a ...

Takanobu Yamaguchi; David A. Randall

2012-03-01T23:59:59.000Z

125

Development and Experimental Validation of Large-Eddy Simulation...  

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

in Syngas Combustion: Characterization of Autoignition, Flashback, and Flame-Liftoff at Gas-Turbine Relevant Operating Conditions- University of Michigan Background The...

126

Large Eddy Simulation of PBL Stratocumulus: Comparison of Multi...  

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

of Multi-Dimensional and IPA Longwave Radiative Forcing D. B. Mechem and Y. L. Kogan Cooperative Institute for Mesoscale Meteorological Studies University of Oklahoma Norman,...

127

On the Magnitude and Variability of Subgrid-Scale Eddy-Diffusion Coefficients in the Atmospheric Surface Layer  

Science Conference Proceedings (OSTI)

Eddy-viscosity closures for large eddy simulations (LES) of atmospheric boundary layer dynamics include a parameter (Smagorinsky constant cs), which depends upon physical parameters, such as distance to the ground, atmospheric stability, and ...

Jan Kleissl; Charles Meneveau; Marc B. Parlange

2003-10-01T23:59:59.000Z

128

An Analysis of Loop Current Frontal Eddies in a Atlantic Ocean Model Simulation  

Science Conference Proceedings (OSTI)

The Loop Current frontal eddies (LCFEs) refer to cyclonic cold eddies moving downstream along the outside edge of the Loop Current in the eastern Gulf of Mexico. They have been observed by in situ measurements and satellite imagery, mostly ...

Haosheng Huang; Nan D. Walker; Ya Hsueh; Yi Chao; Robert R. Leben

2013-09-01T23:59:59.000Z

129

An Analysis of Loop Current Frontal Eddies in a 1/6 Atlantic Ocean Model Simulation  

Science Conference Proceedings (OSTI)

The Loop Current Frontal Eddies (LCFEs) refer to cyclonic cold eddies moving downstream along the outside edge of the Loop Current in the eastern Gulf of Mexico. They have been observed by in-situ measurements and satellite imagery, mostly ...

Haosheng Huang; Nan D. Walker; Ya Hsueh; Yi Chao; Robert R. Leben

130

LES algorithm for turbulent reactive flows simulation  

Science Conference Proceedings (OSTI)

The paper presents the development and implementation of a Large Eddy Simulation numerical algorithm for simulating turbulent reactive flows. The numerical algorithm is based on a 5 step modified Runge - Kutta numerical scheme with a dual time stepping ... Keywords: Runge - Kutta numerical scheme, large eddy simulation, linear eddy model

Ionut Porumbel; Cristian Crl?nescu; Florin Gabriel Florean; Constantin Eusebiu Hritcu

2010-10-01T23:59:59.000Z

131

Adaptive Detached Eddy Simulation of a High-Lift Wing with Active Flow  

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

Full span view of the flow past a vertical tail assembly of a commercial aircraft with active flow control at Re=360,000. Full span view of the flow past a vertical tail assembly of a commercial aircraft with active flow control at Re=360,000. Full span view of the flow past a vertical tail assembly of a commercial aircraft with active flow control at Re=360,000. This picture highlights the root and tip vortex along with the turbulent structures in the wake of a deflected rudder through isosurface of instantaneous Q criterion colored by speed on a locally adapted unstructured finite element mesh with 1.2 billion elements. Michel Rasquin, Argonne National Laboratory Adaptive Detached Eddy Simulation of a High-Lift Wing with Active Flow Control PI Name: Kenneth Jansen PI Email: jansenke@colorado.edu Institution: University of Colorado Allocation Program: INCITE Allocation Hours at ALCF:

132

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

133

Steam Generator Management Program: Simulation Model for Eddy Current Steam Generator Inspection  

Science Conference Proceedings (OSTI)

BackgroundEddy current techniques are used widely to evaluate the integrity of steam generator (SG) tubes in nuclear power plants. A variety of commercial probes have been used by industry; it is well known that eddy current probe responses change as the tube condition changes. Other factors that influence the eddy current signal include deposits, loose parts, and denting. Postulated SG conditions have been mocked up in the laboratory; however, capabilities are limited ...

2013-12-19T23:59:59.000Z

134

Velocity and Eddy Kinetic Energy of the Gulf Stream System from 700-m SOFAR Floats Subsampled to Simulate Pop-up Floats  

Science Conference Proceedings (OSTI)

Velocity and eddy kinetic energy were calculated from SOFAR (sound fixing and ranging) float trajectories using original daily values and values subsampled at intervals of 15, 30, and 60 days to simulate pop-up floats that surface for position ...

P. L. Richardson

1992-08-01T23:59:59.000Z

135

Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean  

Science Conference Proceedings (OSTI)

This paper examines the energy sources for eddy variability in the Gulf of Alaska using a numerical model and a novel form of data assimilation referred to as spectral nudging. Spectral nudging is distinguished from conventional nudging by its ...

Jennifer Shore; Michael W. Stacey; Daniel G. Wright

2008-10-01T23:59:59.000Z

136

Energy of Midlatitude Transient Eddies in Idealized Simulations of Changed Climates  

Science Conference Proceedings (OSTI)

As the climate changes, changes in static stability, meridional temperature gradients, and availability of moisture for latent heat release may exert competing effects on the energy of midlatitude transient eddies. This paper examines how the ...

Paul A. OGorman; Tapio Schneider

2008-11-01T23:59:59.000Z

137

A Primitive Equation Model Simulation of Eddies in the Norwegian Coastal Current  

Science Conference Proceedings (OSTI)

A recent paper by Ikeda, Johannessen, Lygre and Sandven applying a two-layer quasi-geostrophic model to the growth of eddies in the Norwegian Coastal Current contains the comment that a more appropriate model may be a continuously stratified ...

I. D. James

1991-06-01T23:59:59.000Z

138

The Inactive Eddy Motion and the Large-Scale Turbulent Pressure Fluctuations in the Dynamic Sublayer  

Science Conference Proceedings (OSTI)

The statistical structure of the turbulent pressure fluctuations was measured in the dynamic sublayer of a large grass-covered forest clearing by a free air static pressure probe and modeled using Townsend's hypothesis. Townsend's hypothesis ...

Gabriel G. Katul; John D. Albertson; Marc B. Parlange; Cheng-I. Hsieh; Paul S. Conklin; John T. Sigmon; Ken R. Knoerr

1996-09-01T23:59:59.000Z

139

An Energy-Constrained Parameterization of Eddy Buoyancy Flux  

Science Conference Proceedings (OSTI)

A parameterization for eddy buoyancy fluxes for use in coarse-grid models is developed and tested against eddy-resolving simulations. The development is based on the assumption that the eddies are adiabatic (except near the surface) and the ...

Paola Cessi

2008-08-01T23:59:59.000Z

140

Empirical Orthogonal Function Analysis of the Weakly Convective Atmospheric Boundary Layer. Part I: Eddy Structures  

Science Conference Proceedings (OSTI)

Three-dimensional empirical orthogonal functions (EOFs), representing atmospheric turbulence structures, are determined from a large-eddy simulation of a weakly convective, planetary boundary layer. The method of analysis is based on Lumley's ...

D. Keith Wilson

1996-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Mesoscale Eddy Buoyancy Flux and Eddy-Induced Circulation in Eastern Boundary Currents  

Science Conference Proceedings (OSTI)

A dynamical interpretation is made of the mesoscale eddy buoyancy fluxes in the Eastern Boundary Currents off California and PeruChile, based on regional equilibrium simulations. The eddy fluxes are primarily shoreward and upward across a swath ...

Franois Colas; Xavier Capet; James C. McWilliams; Zhijin Li

2013-06-01T23:59:59.000Z

142

Simulating Upwelling in a Large Lake Using Slippery Sacks  

Science Conference Proceedings (OSTI)

A Lagrangian numerical model is used to simulate upwelling in an idealized large lake. This simulation is carried out to test the model's potential for simulating lake and ocean circulations.

Patrick T. Haertel; David A. Randall; Tommy G. Jensen

2004-01-01T23:59:59.000Z

143

Materialized community ground models for large-scale earthquake simulation  

Science Conference Proceedings (OSTI)

Large-scale earthquake simulation requires source datasets which describe the highly heterogeneous physical characteristics of the earth in the region under simulation. Physical characteristic datasets are the first stage in a simulation pipeline which ...

Steven W. Schlosser; Michael P. Ryan; Ricardo Taborda; Julio Lpez; David R. O'Hallaron; Jacobo Bielak

2008-11-01T23:59:59.000Z

144

Advanced concepts in large-scale network simulation  

Science Conference Proceedings (OSTI)

This tutorial paper reviews existing concepts and future directions in selected areas related to simulation of large-scale networks. It covers specifically topics in traffic modeling, simulation of routing, network emulation, and real-time simulation.

David M. Nicol; Michael Liljenstam; Jason Liu

2005-12-01T23:59:59.000Z

145

Spiral Eddies  

Science Conference Proceedings (OSTI)

Small cyclonic spiral eddies with a scale of 10 km are very frequently observed, both from satellites and space shuttles, at the ocean surface. The authors suggest that they are the sea surface signature of ageostrophic baroclinic instabilities. ...

Tor Eldevik; Kristian B. Dysthe

2002-03-01T23:59:59.000Z

146

Large Scale Simulation of Particulate Flows  

Science Conference Proceedings (OSTI)

Simulations of particles in fluid flows are of great interest to numerous industries using sedimentation, fluidization, lubricated transport, and hydraulic fracturing of hydrocarbon reservoirs. Simulating incompressible viscoelastic flows with millions ...

Ahmed H. Sameh; Vivek Sarin

1999-04-01T23:59:59.000Z

147

NREL Develops Simulations for Wind Plant Power and Turbine Loads (Fact Sheet)  

DOE Green Energy (OSTI)

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

Not Available

2012-04-01T23:59:59.000Z

148

Believability in simplifications of large scale physically based simulation  

Science Conference Proceedings (OSTI)

We verify two hypotheses which are assumed to be true only intuitively in many rigid body simulations. I: In large scale rigid body simulation, viewers may not be able to perceive distortion incurred by an approximated simulation method. II: ... Keywords: 3D graphics and realism, animation, physically based simulation

Donghui Han; Shu-wei Hsu; Ann McNamara; John Keyser

2013-08-01T23:59:59.000Z

149

A robust, colocated, implicit algorithm for direct numerical simulation of compressible, turbulent flows  

Science Conference Proceedings (OSTI)

A non-dissipative, robust, implicit algorithm is proposed for direct numerical and large-eddy simulation of compressible turbulent flows. The algorithm addresses the problems caused by low Mach numbers and under-resolved high Reynolds numbers. It colocates ... Keywords: All-Mach number, Compressible turbulence, Direct numerical simulation, Discrete energy conservation, Large-eddy simulation, Non-dissipative

Yucheng Hou; Krishnan Mahesh

2005-05-01T23:59:59.000Z

150

Large eddy simulation of supersonic combustion with application to scramjet engines  

E-Print Network (OSTI)

diffusion term qj Heat flux vector R? Specific gas constant for species ? rd DDES RANS/LES blending parameter Re Reynolds number Rij Reynolds stress tensor Rm Mixture specific gas constant R0 Universal gas constant ~rL, ~rR Vectors from centre of left... and economical access to space. In order to meet these needs and ambitions, significant advancements in propulsion technol- ogy are required. The gas turbine engines commonly employed in subsonic and low supersonic aircraft are not practical above flight Mach...

Cocks, Peter

2011-07-12T23:59:59.000Z

151

Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer  

E-Print Network (OSTI)

SBL are used to improve wind farm siting and nighttimeapplications such as wind farm operations, numerical weathersuggests implications for wind farm siting and operations.

Zhou, Bowen

2012-01-01T23:59:59.000Z

152

Large Eddy Simulation of Thermo-Hydraulic Mixing in a T-Junction...  

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

been the topic of concern in the nuclear engineering community because of the relation to thermal fatigue of nuclear power plant pipe systems. When turbulent flow streams of...

153

Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer  

E-Print Network (OSTI)

responses in the turbine rotor as well as the supportingthe rotor sweep area of the generic wind turbine between 40turbine micro-siting, obtain reliable estimates of wind resources, and prevent rotor

Zhou, Bowen

2012-01-01T23:59:59.000Z

154

Dynamics of Sheared Convective Boundary Layer Entrainment. Part I: Methodological Background and Large-Eddy Simulations  

Science Conference Proceedings (OSTI)

The reported study examines the dynamics of entrainment and its effects on the evolution of the dry atmospheric convective boundary layer (CBL) when wind shear is present. The sheared CBL can be studied by means of direct measurements in the ...

Robert J. Conzemius; Evgeni Fedorovich

2006-04-01T23:59:59.000Z

155

Numerical Issues of Monte Carlo PDF for Large Eddy Simulations of Turbulent Flames  

E-Print Network (OSTI)

piloted methane jet flame (Sandia Flame D), Presented atof a pure mixing jet and Sandia Flame D using a steady-stateon pure mixing jet and Sandia flame D with a steady-

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

156

Lagrangian Particle Dispersion Modeling of the Fumigation Process Using Large-Eddy Simulation  

Science Conference Proceedings (OSTI)

A Lagrangian particle dispersion model (LPDM) is used to study fumigation of pollutants in and above the entrainment zone into a growing convective boundary layer. Probability density functions of particle location with height and time are ...

Si-Wan Kim; Chin-Hoh Moeng; Jeffrey C. Weil; Mary C. Barth

2005-06-01T23:59:59.000Z

157

Large-eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer  

E-Print Network (OSTI)

time of emitted gases from the landfill to the measurementgas profiles, and gas travel times from the landfill to theterm methane gas emission over a landfill. A brief summary

Zhou, Bowen

2012-01-01T23:59:59.000Z

158

Large-Eddy Simulation of Evaporatively Driven Entrainment in Cloud-Topped Mixed Layers  

Science Conference Proceedings (OSTI)

Cloud-top entrainment instability (CTEI) is a hypothesized positive feedback between cloud-top entrainment and enhanced turbulence associated with buoyancy reversal. A sufficiently strong positive feedback is hypothesized to lead to the ...

Takanobu Yamaguchi; David A. Randall

2008-05-01T23:59:59.000Z

159

Large Eddy Simulation of Wind Loads on a Low-Rise ...  

Science Conference Proceedings (OSTI)

... Dynamics (CFD), referred as virtual wind tunnel ... Tunnel Laboratory of the University of Western ... dynamic Smagorinsky-Lilly model does implement a ...

2013-07-24T23:59:59.000Z

160

Numerical Issues of Monte Carlo PDF for Large Eddy Simulations of Turbulent Flames  

E-Print Network (OSTI)

Carlo PDF Methods for Turbulent Diffusion Flames, Combust.Flame 124:519-534 (2001). Muradoglu, M. , Jenny, P. Pope,Methane-Air Nonpremixed Jet Flames, Combustion Science and

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Detailed documentation of the direct effects of large eddy break-up devices on the turbulence structure in turbulent boundary layers  

SciTech Connect

The direct effect of a single large eddy break up (LEBU) device on the turbulence structure in a turbulent boundary layer was investigated by acquiring detailed three dimensional measurements of all velocity components in the near field of the manipulator. It was found that the incoming large vortical structures are completely suppressed by the LEBU. The suppression of these large scale structures results in a drastic reduction of the entrainment of high speed potential flow. In turn, this results in a reduction of the growth rate of the boundary layer and therefore of the local skin friction, as suggested by the momentum theorem. It was also found that the suppression of these size eddies is attributed to a direct inhibition of the normal component of velocity by the manipulator as they travel over it, and that the streamwise and spanwise fluctuations observed on top of the manipulator downstream of its leading edge are merely passive 'scares' of these incoming large vortical structure, not associated to any significant active transport of momentum. The smaller structures residing lower within the boundary layer were found to be indirectly effected by the overall circulation field around the manipulator. Furthermore, being trapped under the manipulator, these structures are shielded from any interaction with the high speed potential flow, which in turn leads to a weakening of scales on a wider spectrum. Moreover, the wake of the manipulator was found to act as an extension to the manipulator itself to inhibit the normal component of velocity therefore shielding against normal momentum transfer between the structures trapped underneath the manipulator and the outer part of the flow field. This shielding effects is achieved by the localized introduction of small, energetic structures in the wake of the manipulator which are completely uncorrelated with those in the rest of the boundary layer.

Trigui, N.

1991-01-01T23:59:59.000Z

162

A holonic approach to model and deploy large scale simulations  

Science Conference Proceedings (OSTI)

Multi-Agent Based Simulations (MABS) for real-world problems may require a large number of agents. A possible solution is to distribute the simulation in multiple machines. Thus, we are forced to consider how Large Scale MABS can be deployed in order ...

Sebastian Rodriguez; Vincent Hilaire; Abder Koukam

2006-05-01T23:59:59.000Z

163

A Simulator for Large-Scale Parallel Computer Architectures  

Science Conference Proceedings (OSTI)

Efficient design of hardware and software for large-scale parallel execution requires detailed understanding of the interactions between the application, computer, and network. The authors have developed a macro-scale simulator SST/macro that permits ... Keywords: Computer Architecture Simulation, Macro-scale Simulator, Message Passing Interface, Network Congestion, Network Models

Helgi Adalsteinsson; Scott Cranford; David A. Evensky; Joseph P. Kenny; Jackson Mayo; Ali Pinar; Curtis L. Janssen

2010-04-01T23:59:59.000Z

164

Performance of an Eddy DiffusivityMass Flux Scheme for Shallow Cumulus Boundary Layers  

Science Conference Proceedings (OSTI)

Comparisons between single-column (SCM) simulations with the total energymass flux boundary layer scheme (TEMF) and large-eddy simulations (LES) are shown for four cases from the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) ...

Wayne M. Angevine; Hongli Jiang; Thorsten Mauritsen

2010-07-01T23:59:59.000Z

165

Global Patterns of Mesoscale Eddy Properties and Diffusivities  

Science Conference Proceedings (OSTI)

Mesoscale eddies play a major role in the transport of tracers in the ocean. Focusing on a sector in the East Pacific, we present estimates of eddy diffusivities derived from kinematic tracer simulations using satellite-observed velocity fields. ...

Andreas Klocker; Ryan Abernathey

166

The Santa Cruz Eddy. Part II: Mechanisms of Formation  

Science Conference Proceedings (OSTI)

The formation mechanism of the Santa Cruz eddy (SCE) is investigated using the fifth-generation Pennsylvania State UniversityNational Center for Atmospheric Research Mesoscale Model (MM5). Simulations of 2526 August 2000 showed that two eddy ...

Cristina L. Archer; Mark Z. Jacobson

2005-08-01T23:59:59.000Z

167

Mesoscale Eddy Energy Locality in an Idealized Ocean Model  

Science Conference Proceedings (OSTI)

This paper investigates the energy budget of mesoscale eddies in wind-driven two-layer quasigeostrophic simulations. Intuitively, eddy energy can be generated, dissipated, and fluxed from place to place; regions where the budget balances ...

Ian Grooms; Louis-Philippe Nadeau; K. Shafer Smith

2013-09-01T23:59:59.000Z

168

Large-Scale Hybrid Dynamic Simulation Employing Field Measurements  

Science Conference Proceedings (OSTI)

Simulation and measurements are two primary ways for power engineers to gain understanding of system behaviors and thus accomplish tasks in system planning and operation. Many well-developed simulation tools are available in today's market. On the other hand, large amount of measured data can be obtained from traditional SCADA systems and currently fast growing phasor networks. However, simulation and measurement are still two separate worlds. There is a need to combine the advantages of simulation and measurements. In view of this, this paper proposes the concept of hybrid dynamic simulation which opens up traditional simulation by providing entries for measurements. A method is presented to implement hybrid simulation with PSLF/PSDS. Test studies show the validity of the proposed hybrid simulation method. Applications of such hybrid simulation include system event playback, model validation, and software validation.

Huang, Zhenyu; Guttromson, Ross T.; Hauer, John F.

2004-06-30T23:59:59.000Z

169

Vermont Yankee simulator qualification: large-break LOCA  

Science Conference Proceedings (OSTI)

Yankee Atomic Electric Company (YAEC) has developed simulator benchmark capabilities for the Seabrook, Maine Yankee, and Vermont Yankee Nuclear Power Station (VYNPS) simulators. The goal is to establish that each simulator has a satisfactory real-time response for different scenarios that will enhance operator training. Vermont Yankee purchased a full-scope plane simulator for the VYNPS, a four-unit boiling water reactor with a Mark-I containment. The following seven benchmark cases were selected by YAEC and VYNPC to supplement the Simulator Acceptance Test Program: (1) control rod swap; (2) partial reactor scram; (3) recirculation pump trip; (4) main steam isolation valve (MSIV) closure without scram, (5) main steamline break, (6) small-break loss-of-coolant accident (LOCA), and (7) large-break LOCA. Five simulator benchmark sessions have been completed. Each session identified simulator capabilities and limitations that needed correction. This paper discusses results from the latest large-break LOCA case.

Loomis, J.N.; Fernandez, R.T.

1987-01-01T23:59:59.000Z

170

Large-Scale Parallel Computing of Cloud Resolving Storm Simulator  

Science Conference Proceedings (OSTI)

A sever thunderstorm is composed of strong convective clouds. In order to perform a simulation of this type of storms, a very finegrid system is necessary to resolve individual convective clouds within a large domain. Since convective clouds are highly ...

Kazuhisa Tsuboki; Atsushi Sakakibara

2002-05-01T23:59:59.000Z

171

In Situ Visualization for Large-Scale Combustion Simulations  

Science Conference Proceedings (OSTI)

As scientific supercomputing moves toward petascale and exascale levels, in situ visualization stands out as a scalable way for scientists to view the data their simulations generate. This full picture is crucial particularly for capturing and understanding ... Keywords: in situ visualization, large-scale simulation, parallel rendering, supercomputing, scalability, computer graphics, graphics and multimedia

Hongfeng Yu; Chaoli Wang; Ray W. Grout; Jacqueline H. Chen; Kwan-Liu Ma

2010-05-01T23:59:59.000Z

172

An Evaluation of the Network Simulators in Large-Scale Distributed Simulations  

Science Conference Proceedings (OSTI)

This is a survey paper about the state-of-the-art in large-scale network simulation. Networks for the smart grids are characterized by millions of sensor nodes exchanging information about the status of the grid. This information exchange must be realized reliably and efficiently due to the mission critical nature of the power grid. Hence, the applications and the network protocols developed for the smart grid need go through rigorous testing and analysis before deployment. Developers usually do not have access to such a large-scale network that can be used as a controlled test-bed; therefore, network simulation becomes an essential tool for testing. Network simulation is a well studied problem in the literature and there are various widely used network simulators. These simulators can be adopted for testing applications and protocols of the smart grid. Due to the scale of these networks, parallel/distributed simulations need to be conducted. Even though most network simulators support distributed simulations, generating a large-scale network model to simulate can still be a cumbersome task. In this survey, we describe a selection of commonly used network simulators and evaluate them with respect to the following features that can aid users in distributed simulations of large-scale networks: transparency of setting up distributed simulation, automated topology generation, information hiding, lightweight routing protocols, network error simulation, evaluation of the network model during simulation and trace analysis tools. As a complementary result, we identify two issues with network simulators that can be addressed with runtime steering methods.

Ciraci, Selim; Akyol, Bora A.

2011-11-13T23:59:59.000Z

173

An Investigation of the Catalina Eddy  

Science Conference Proceedings (OSTI)

The Catalina eddy event of 21 July 1992 is simulated using a mesoscale data assimilation system featuring an optimum interpolation analysis, incremental update, and second-order closure physics. The results are contrasted with other recent ...

William T. Thompson; Stephen D. Burk; J. Rosenthal

1997-06-01T23:59:59.000Z

174

Computer simulations of exponentially convergent networks with large impulses  

Science Conference Proceedings (OSTI)

This paper demonstrates the use of a semi-discretization technique for obtaining a discrete-time analogue of an exponentially convergent network that is subject to impulses with large magnitude. Prior to implementing the analogue for computer simulations, ... Keywords: 39A12, 65Q05, 92B20, Discrete-time analogue, Exponential stability, Impulses, Semi-discretization

Sannay Mohamad

2008-04-01T23:59:59.000Z

175

Idealized Numerical Simulations of the Interactions between Buoyant Plumes and Density Currents  

Science Conference Proceedings (OSTI)

Idealized numerical experiments using a large-eddy simulation (LES) model are performed to examine the fundamental dynamical processes associated with the interactions between buoyant plumes and density currents. The aim of these simulations is ...

Philip Cunningham

2007-06-01T23:59:59.000Z

176

Numerical Simulation of Katabatic Flow with Changing Slope Angle  

Science Conference Proceedings (OSTI)

A large eddy simulation (LES) model and the Advanced Regional Prediction System (ARPS) model, which does not resolve turbulent eddies, are used to study the effect of a slope angle decrease on the structure of katabatic slope flows. For a simple, ...

Craig M. Smith; Eric D. Skyllingstad

2005-11-01T23:59:59.000Z

177

New Aerodynamics Simulations Provide Better Understanding of Wind Plant Underperformance and Loading (Fact Sheet)  

DOE Green Energy (OSTI)

Researchers at the National Renewable Energy Laboratory (NREL) develop a high-fidelity large-eddy simulation model designed to predict the performance of large wind plants with a higher degree of accuracy than current models.

Not Available

2011-02-01T23:59:59.000Z

178

Lightweight computational steering of very large scale molecular dynamics simulations  

Science Conference Proceedings (OSTI)

We present a computational steering approach for controlling, analyzing, and visualizing very large scale molecular dynamics simulations involving tens to hundreds of millions of atoms. Our approach relies on extensible scripting languages and an easy to use tool for building extensions and modules. The system is extremely easy to modify, works with existing C code, is memory efficient, and can be used from inexpensive workstations and networks. We demonstrate how we have used this system to manipulate data from production MD simulations involving as many as 104 million atoms running on the CM-5 and Cray T3D. We also show how this approach can be used to build systems that integrate common scripting languages (including Tcl/Tk, Perl, and Python), simulation code, user extensions, and commercial data analysis packages.

Beazley, D.M. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Computer Science; Lomdahl, P.S. [Los Alamos National Lab., NM (United States)

1996-09-01T23:59:59.000Z

179

Environmental Controls on the Surface Energy Budget over a Large Southern Inland Water in the United States: An Analysis of One-Year Eddy Covariance Flux Data  

Science Conference Proceedings (OSTI)

The authors analyzed the surface energy fluxes that were measured by an eddy covariance system over the Ross Barnett Reservoir in Mississippi for a 1-yr period in 2008. On a monthly basis over the course of the year, positive vertical temperature ...

Heping Liu; Qianyu Zhang; Gordon Dowler

2012-12-01T23:59:59.000Z

180

Advanced coal gasifier designs using large-scale simulations  

Science Conference Proceedings (OSTI)

Porting of the legacy code MFIX to a high performance computer (HPC) and the use of high resolution simulations for the design of a coal gasifier are described here. MFIX is based on a continuum multiphase flow model that considers gas and solids to form interpenetrating continua. Low resolution simulations of a commercial scale gasifier with a validated MFIX model revealed interesting physical phenomena with implications on the gasifier design, which prompted the study reported here. To be predictive, the simulations need to model the spatiotemporal variations in gas and solids volume fractions, velocities, temperatures with any associated phase change and chemical reactions. These processes occur at various time- and length-scales requiring very high spatial resolution and large number of iterations with small time-steps. We were able to perform perhaps the largest known simulations of gas-solids reacting flows, providing detailed information about the gas-solids flow structure and the pressure, temperature and species distribution in the gasifier. One key finding is the new features of the coal jet trajectory revealed with the high spatial resolution, which provides information on the accuracy of the lower resolution simulations. Methodologies for effectively combining high and low resolution simulations for design studies must be developed. From a computational science perspective, we found that global communication has to be reduced to achieve scalability to 1000s of cores, hybrid parallelization is required to effectively utilize the multicore chips, and the wait time in the batch queue significantly increases the actual time-to-solution. From our experience, development is required in the following areas: efficient solvers for heterogeneous, massively parallel systems; data analysis tools to extract information from large data sets; and programming environments for easily porting legacy codes to HPC.

Syamlal, M [National Energy Technology Laboratory (NETL); Guenther, Chris [National Energy Technology Laboratory (NETL); Gel, Aytekin [Aeolus Research Inc.; Pannala, Sreekanth [ORNL

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Simulation of large photomultipliers for experiments in astroparticle physics  

E-Print Network (OSTI)

We have developed an accurate simulation model of the large 9 inch photomultiplier tubes (PMT) used in water-Cherenkov detectors of cosmic-ray induced extensive air-showers. This work was carried out as part of the development of the Offline simulation software for the Pierre Auger Observatory surface array, but our findings may be relevant also for other astrophysics experiments that employ similar large PMTs. The implementation is realistic in terms of geometrical dimensions, optical processes at various surfaces, thin-film treatment of the photocathode, and photon reflections on the inner structure of the PMT. With the quantum efficiency obtained for this advanced model we have calibrated a much simpler and a more rudimentary model of the PMT which is more practical for massive simulation productions. We show that the quantum efficiency declared by manufactures of the PMTs is usually determined under conditions substantially different from those relevant for the particular experiment and thus requires careful (re)interpretation when applied to the experimental data or when used in simulations. In principle, the effective quantum efficiency could vary depending on the optical characteristics of individual events.

Alexandre Creusot; Darko Veberic

2010-01-08T23:59:59.000Z

182

NREL Developing Numerical Simulation Tool to Study Hydrokinetic...  

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

M.; Li, Y.; Moriarty, P. (2012). "A Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines." Accepted by Proceedings of the...

183

Molecular Dynamics Simulations from SNL's Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)  

DOE Data Explorer (OSTI)

LAMMPS (http://lammps.sandia.gov/index.html) stands for Large-scale Atomic/Molecular Massively Parallel Simulator and is a code that can be used to model atoms or, as the LAMMPS website says, as a parallel particle simulator at the atomic, meso, or continuum scale. This Sandia-based website provides a long list of animations from large simulations. These were created using different visualization packages to read LAMMPS output, and each one provides the name of the PI and a brief description of the work done or visualization package used. See also the static images produced from simulations at http://lammps.sandia.gov/pictures.html The foundation paper for LAMMPS is: S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995), but the website also lists other papers describing contributions to LAMMPS over the years.

Plimpton, Steve; Thompson, Aidan; Crozier, Paul

184

Jovian Winds from Voyager 2. Part II: Analysis of Eddy Transports  

Science Conference Proceedings (OSTI)

Previous Voyager 1 and 2 Jovian circulation measurements exhibit a large positive correlation between eddy momentum transports and the meridional shear of the zonal wind component, implying a very large rate of conversion of eddy kinetic energy ...

L. A. Sromovsky; H. E. Revercomb; V. E. Suomi; S. S. Limaye; R. J. Krauss

1982-07-01T23:59:59.000Z

185

In-situ sampling of a large-scale particle simulation for interactive visualization and analysis  

Science Conference Proceedings (OSTI)

We describe a simulation-time random sampling of a large-scale particle simulation, the RoadRunner Universe MC3 cosmological simulation, for interactive post-analysis and visualization. Simulation data generation rates will continue to be ...

J. Woodring; J. Ahrens; J. Figg; J. Wendelberger; S. Habib; K. Heitmann

2011-06-01T23:59:59.000Z

186

Diagnoses of an Eddy-Resolving Atlantic Ocean Model Simulation in the Vicinity of the Gulf Stream. Part I: Potential Vorticity  

Science Conference Proceedings (OSTI)

Output of an eddy-resolving model of the North Atlantic is diagnosed in the vicinity of the Gulf Stream (GS), using quasigeostrophic potential vorticity (QGPV), Ertels potential vorticity (PV), and particle trajectories. Time series of QGPV show ...

Mototaka Nakamura; Yi Chao

2001-02-01T23:59:59.000Z

187

On the Maintenance of Stationary Eddies in Terms of the Streamfunction Budget Analysis  

Science Conference Proceedings (OSTI)

The upper-level seasonal-mean eddy streamfunction (??E) is often used to portray atmospheric stationary eddies. A budget analysis of the 200 mb ??E field simulated by the NCAR Community Climate Model revealed that a quadrature relationship exists ...

Tsing-Chang Chen; Jau-Ming Chen

1990-12-01T23:59:59.000Z

188

A time management optimization framework for large-scale distributed hardware-in-the-loop simulation  

Science Conference Proceedings (OSTI)

Large-scale distributed HIL(Hardware-In-The-Loop) simulation is an important and indispensable method for testing and verifying complex engineering systems. An important necessary condition for realizing HIL simulation is that the speedup ratio of full-speed ... Keywords: hardware-in-the-loop simulation, large-scale distributed simulation, optimization framework, speedup ratio of simulation, time management

Wei Dong

2013-05-01T23:59:59.000Z

189

Eddy Current Instruments  

Science Conference Proceedings (OSTI)

Table 2   Types and capabilities of commercially available eddy current instruments...measurement of four variables, analog

190

Cosmological Simulations for Large-Scale Sky Surveys | Argonne Leadership  

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

Instantaneous velocity magnitude in a flow through an open valve in a valve/piston assembly. Instantaneous velocity magnitude in a flow through an open valve in a valve/piston assembly. Instantaneous velocity magnitude in a flow through an open valve in a valve/piston assembly. Christos Altantzis, MIT, and Martin Schmitt, LAV. All the images were generated from their work at LAV. Cosmological Simulations for Large-Scale Sky Surveys PI Name: Christos Frouzakis PI Email: frouzakis@lav.mavt.ethz.ch Institution: Swiss Federal Institute of Technology Zurich Allocation Program: INCITE Allocation Hours at ALCF: 100 Million Year: 2014 Research Domain: Chemistry The combustion of coal and petroleum-based fuels supply most of the energy needed to meet the world's transportation and power generation demands. To address the anticipated petroleum shortage, along with increasing energy

191

Surface detection, meshing and analysis during large molecular dynamics simulations  

SciTech Connect

New techniques are presented for the detection and analysis of surfaces and interfaces in atomistic simulations of solids. Atomistic and other particle-based simulations have no inherent notion of a surface, only atomic positions and interactions. The algorithms we introduce here provide an unambiguous means to determine which atoms constitute the surface, and the list of surface atoms and a tessellation (meshing) of the surface are determined simultaneously. The algorithms have been implemented and demonstrated to run automatically (on the fly) in a large-scale parallel molecular dynamics (MD) code on a supercomputer. We demonstrate the validity of the method in three applications in which the surfaces and interfaces evolve: void surfaces in ductile fracture, the surface morphology due to significant plastic deformation of a nanoscale metal plate, and the interfaces (grain boundaries) and void surfaces in a nanoscale polycrystalline system undergoing ductile failure. The technique is found to be quite robust, even when the topology of the surfaces changes as in the case of void coalescence where two surfaces merge into one. It is found to add negligible computational overhead to an MD code, and is much less expensive than other techniques such as the solvent-accessible surface.

Dupuy, L M; Rudd, R E

2005-08-01T23:59:59.000Z

192

An Immersed Boundary Method Enabling Large-Eddy Simulations of Flow over Complex Terrain in the WRF Model  

Science Conference Proceedings (OSTI)

This paper describes a three-dimensional immersed boundary method (IBM) that facilitates the explicit resolution of complex terrain within the Weather Research and Forecasting (WRF) model. Two interpolation methodstrilinear and inverse distance ...

Katherine A. Lundquist; Fotini Katopodes Chow; Julie K. Lundquist

2012-12-01T23:59:59.000Z

193

Comparison of Convective Boundary Layer Velocity Spectra Retrieved from Large Eddy Simulation and Weather Research and Forecasting Model Data  

Science Conference Proceedings (OSTI)

As computing capabilities expand, operational and research environments are moving toward the use of fine-scale atmospheric numerical models. These models are attractive for users who seek accurate description of small-scale turbulent motions. One ...

Jeremy A. Gibbs; Evgeni Fedorovich

194

Hybrid simulation of large electrical networks with assymmetrical fault modelling  

Science Conference Proceedings (OSTI)

Owing to the increasing attention placed on dynamic security assessment in the light of recent blackouts, hybrid simulation, involving the interfacing of electromagnetic transients (EMT) simulators and transient stability (TS) simulators for the more ... Keywords: asymmetrical fault modelling, electromagnetic transients, hybrid simulation, interaction protocol, transient stability

H. T. Su; K. W. Chan; L. A. Snider

2008-03-01T23:59:59.000Z

195

Radiative Impacts on the Growth of Drops within Simulated Marine Stratocumulus. Part I: Maximum Solar Heating  

Science Conference Proceedings (OSTI)

The effects of solar heating and infrared cooling on the vapor depositional growth of cloud drops, and hence the potential for collection enhancement, is investigated. Large eddy simulation (LES) of marine stratocumulus is used to generate 600 ...

Christopher M. Hartman; Jerry Y. Harrington

2005-07-01T23:59:59.000Z

196

Numerical Simulation of Pollutant Emission and Flame Extinction in Lean Premixed Systems .  

E-Print Network (OSTI)

??Premixed and partially-premixed combustion and ollutant emissions in full-scale gas turbines has been numerically investigated using a massively-parallel Large-Eddy Simulation Combustion Dynamics Model. Through the (more)

Eggenspieler, Gilles

2005-01-01T23:59:59.000Z

197

Interface Exchange as an Indicator for Eddy Heat Transport  

Science Conference Proceedings (OSTI)

The ocean contains many large-scale, long-lived vortices, called mesoscale eddies, that are believed to have a role in the transport and redistribution of salt, heat, and nutrients throughout the ocean. Determining this role, however, has proven to be a challenge, since the mechanics of eddies are only partly understood; a standard definition for these ocean eddies does not exist and, therefore, scientifically meaningful, robust methods for eddy extraction, characterization, tracking and visualization remain a challenge. In order to shed light on the nature and potential roles of eddies, we have combined our previous research on eddy identification and tracking, and have used those approaches as the basis for analysis-driven computational experiments on the nature of eddies. Based on the resulting visualizations of eddy behavior, we have devised a new metric to characterize the transfer of water into and out of eddies across their boundary, and have developed visualization methods for this new metric to provide clues about the role eddies play in the global ocean and, potentially, climate change.

Petersen, Mark R. [Los Alamos National Laboratory; Williams, Sean J. [Los Alamos National Laboratory; Hecht, Matthew W. [Los Alamos National Laboratory; Maltrud, Mathew E. [Los Alamos National Laboratory; Hamann, Bernd [U of California Davis; Patchett, John M. [Los Alamos National Laboratory; Ahrens, James P. [Los Alamos National Laboratory

2012-06-12T23:59:59.000Z

198

Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.  

SciTech Connect

In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.

Smith, William S. [Los Alamos National Laboratory; Bull, Jeffrey S. [Los Alamos National Laboratory; Wilcox, Trevor [Los Alamos National Laboratory; Bos, Randall J. [Los Alamos National Laboratory; Shao, Xuan-Min [Los Alamos National Laboratory; Goorley, John T. [Los Alamos National Laboratory; Costigan, Keeley R. [Los Alamos National Laboratory

2012-08-13T23:59:59.000Z

199

Large-Scale Atomistic Simulations of Material Failure  

DOE Data Explorer (OSTI)

These simulations examine the supersonic propagation of cracks and the formation of complex junction structures in metals. Eight simulations concerning brittle fracture, ductile failure, and shockless compression are available.

Abraham, Farid [IBM Almaden Research; Duchaineau, Mark [LLNL; Diaz De La Rubia, Tomas (LLNL); Wirth, Brian [LLNL; Heidelberg,; Seager, Mark [LLNL

200

Mixing by ocean eddies  

E-Print Network (OSTI)

Mesoscale eddies mix and transport tracers such as heat and potential vorticity laterally in the ocean. While this transport plays an important role in the climate system, especially in the Southern Ocean, we lack a, ...

Abernathey, Ryan (Ryan Patrick)

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Computational Challenges in Simulating Large DNA over Long Times  

Science Conference Proceedings (OSTI)

Simulating DNAs dynamics requires a sophisticated array of algorithms appropriate for DNAs impressive spectrum of spatial and temporal levels. The authors describe computational challenges

Tamar Schlick; Daniel A. Beard; Jing Huang; Daniel A. Strahs; Xiaoliang Qian

2000-01-01T23:59:59.000Z

202

A process and control simulator for large scale cryogenic plants Benjamin Bradua,b,  

E-Print Network (OSTI)

. To cool-down and maintain superconductivity, large helium refrigeration plants are used, see Lebrun (1999 to the large number of correlated variables on wide operation ranges. Currently, the design and the control. This simulator is able to simulate large refrigeration plants using helium and connected to the actual control

Paris-Sud XI, Université de

203

Eddy Modulation of AirSea Interaction and Convection  

Science Conference Proceedings (OSTI)

Eddy modulation of the airsea interaction and convection that occurs in the process of mode water formation is analyzed in simulations of a baroclinically unstable wind- and buoyancy-driven jet. The watermass transformation analysis of Walin is ...

Ivana Cerove?ki; John Marshall

2008-01-01T23:59:59.000Z

204

Energy Flux to a Cyclonic Eddy off Cabo Frio, Brazil  

Science Conference Proceedings (OSTI)

To evaluate the energy flux from the mean flow of South Atlantic western boundary currents toward typical Cabo Frio eddies (at Brazilian southeast coast), the southwestern Atlantic circulation was simulated with the Princeton Ocean Model. ...

Manlio F. Mano; Afonso M. Paiva; Audalio R. Torres Jr.; Alvaro L. G. A. Coutinho

2009-11-01T23:59:59.000Z

205

Traces generation to simulate large-scale distributed applications  

Science Conference Proceedings (OSTI)

In order to study the performance of scheduling algorithms, simulators of parallel and distributed applications need accurate models of the application's behavior during execution. For this purpose, traces of low-level events collected during the actual ...

Olivier Dalle; Emilio P. Mancini

2011-12-01T23:59:59.000Z

206

High performance threaded data streaming for large scale simulations  

E-Print Network (OSTI)

We have developed a threaded parallel data streaming approach using Logistical Networking (LN) to transfer multi-terabyte simulation data from computers at NERSC to our local analysis/visualization cluster, as the simulation executes, with negligible overhead. Data transfer experiments show that this concurrent data transfer approach is more favorable compared with writing to local disk and later transferring this data to be post-processed. Our algorithms are network aware, and can stream data at up to 97Mbs on a 100Mbs link from CA to NJ during a live simulation, using less than 5 % CPU overhead at NERSC. This method is the first step in setting up a pipeline for simulation workflow and data management. 1.

Viraj Bhat; Scott Klasky; Scott Atchley; Micah Beck; Doug Mccune; Manish Parashar

2004-01-01T23:59:59.000Z

207

The Oceanic Eddy Heat Transport  

Science Conference Proceedings (OSTI)

The rectified eddy heat transport is calculated from a global high-resolution ocean general circulation model. The eddy heat transport is found to be strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial ...

Steven R. Jayne; Jochem Marotzke

2002-12-01T23:59:59.000Z

208

Numerical Simulation of Dust Lifting within Dust DevilsSimulation of an Intense Vortex  

Science Conference Proceedings (OSTI)

Based on an advanced dust devilscale large-eddy simulation (LES) model, the atmosphere flow of a modeled dust devil in a quasisteady state was first simulated to illustrate the characteristics of the gas phase field in the mature stage, ...

Zhaolin Gu; Yongzhi Zhao; Yun Li; Yongzhang Yu; Xiao Feng

2006-10-01T23:59:59.000Z

209

An Eddy-Permitting Southern Ocean State Estimate  

Science Conference Proceedings (OSTI)

An eddy-permitting general circulation model of the Southern Ocean is fit by constrained least squares to a large observational dataset during 200506. Data used include Argo float profiles, CTD synoptic sections, Southern Elephant Seals as ...

Matthew R. Mazloff; Patrick Heimbach; Carl Wunsch

2010-05-01T23:59:59.000Z

210

Ocean Eddy Dynamics in a Coupled OceanAtmosphere Model  

Science Conference Proceedings (OSTI)

The role of mesoscale oceanic eddies is analyzed in a quasigeostrophic coupled oceanatmosphere model operating at a large Reynolds number. The model dynamics are characterized by decadal variability that involves nonlinear adjustment of the ...

P. Berloff; W. Dewar; S. Kravtsov; J. McWilliams

2007-05-01T23:59:59.000Z

211

LogGOPSim: simulating large-scale applications in the LogGOPS model  

Science Conference Proceedings (OSTI)

We introduce LogGOPSim---a fast simulation framework for parallel algorithms at large-scale. LogGOPSim utilizes a slightly extended version of the well-known LogGPS model in combination with full MPI message matching semantics and detailed simulation ... Keywords: LogGOPS model, LogGP, LogGPS, LogP, collective operations, large-scale performance, message passing interface, simulation

Torsten Hoefler; Timo Schneider; Andrew Lumsdaine

2010-06-01T23:59:59.000Z

212

Large Scale Simulations of Jets in Dense and Magnetised Environments  

E-Print Network (OSTI)

We report two simulations that have been carried out at the SX-5 at HLRS (Stuttgart). One simulation is axisymmetric and purely hydrodynamic, but with a resolution of 20 points per beam-radius (ppb). The bipolar jet is injected in the center of a spherically symmetric King profile, initially underdense to its environment by a factor of 10,000. As expected from our previous work, the jet starts with producing a spherical bubble around it, bounded by the bow shock. The bubble slowly elongates, first with roughly elliptical shape, and then forms narrower extensions in beam direction. The final aspect ratio of the bow shock is 1.8. We have transformed the results on a 3D-rectangular grid and integrated the emission properties to compare the results with observed central cluster radio galaxies. In the particular case of Cygnus A, we come to convincing consistency, morphologically, regarding the size of the influenced region by the jet, size, and cylindrical shape of the radio cocoon, and source age. This strongly supports our earlier hypothesis on the nature of the jet in Cygnus A, and the derived constraints on other jet parameters like a power of $8 \\times 10^{46}$ erg/s and an age of 27 Myr. But, the simulation also clearly shows the shortcoming of the model: The jet's beam is very unstable, reaching the tip of the bow shock only very seldom. Also, the contact discontinuity between shocked beam plasma and shocked ambient gas is quite disrupted by the action of the Kelvin-Helmholtz-instability. This is not seen in observations, and necessitates the presence of dynamically important magnetic fields or an at least moderately relativistic flow, or both. [abridged

Martin G. H. Krause; Max Camenzind

2003-07-08T23:59:59.000Z

213

Elements of the Microphysical Structure of Numerically Simulated Nonprecipitating Stratocumulus  

Science Conference Proceedings (OSTI)

A set of 500 simulated trajectories and a simple parcel model are used to (i) evaluate the performance of a large eddy simulation model coupled to a detailed representation of the droplet spectrum (the LES-BM model) and (ii) gain insight into the ...

Bjorn Stevens; Graham Feingold; William R. Cotton; Robert L. Walko

1996-04-01T23:59:59.000Z

214

On-demand computation of policy based routes for large-scale network simulation  

Science Conference Proceedings (OSTI)

Routing table storage demands pose a significant obstacle for large-scale network simulation. On-demand computation of routes can alleviate those problems for models that do not require representation of routing dynamics. However, policy based routes, ...

Michael Liljenstam; David M. Nicol

2004-12-01T23:59:59.000Z

215

A case study in meta-simulation design and performance analysis for large-scale networks  

Science Conference Proceedings (OSTI)

Simulation and emulation techniques are fundamental to aid the process of large-scale protocol design and network operations. However, the results from these techniques are often view with a great deal of skepticism from the networking community. Criticisms ...

David Bauer; Garrett Yaun; Christopher D. Carothers; Murat Yuksel; Shivkumar Kalyanaraman

2004-12-01T23:59:59.000Z

216

Anisotropic mesoscopic traffic simulation approach to support large-scale traffic and logistic modeling and analysis  

Science Conference Proceedings (OSTI)

Large-scale traffic and transportation logistics analysis requires a realistic depiction of network traffic condition in a dynamic manner. In the past decades, vehicular traffic simulation approaches have been increasingly developed and applied to describe ...

Ye Tian; Yi-Chang Chiu

2011-12-01T23:59:59.000Z

217

Astrophysical particle simulations with large custom GPU clusters on three continents  

Science Conference Proceedings (OSTI)

We present direct astrophysical N-body simulations with up to six million bodies using our parallel MPI-CUDA code on large GPU clusters in Beijing, Berkeley, and Heidelberg, with different kinds of GPU hardware. The clusters are linked in the ... Keywords: Computational astrophysics, GPU clusters, N-Body simulations

R. Spurzem; P. Berczik; I. Berentzen; K. Nitadori; T. Hamada; G. Marcus; A. Kugel; R. Mnner; J. Fiestas; R. Banerjee; R. Klessen

2011-06-01T23:59:59.000Z

218

Development of a Two-Dimensional Zonally Averaged Statistical-Dynamical Model.Part II: The Role of Eddy Momentum Fluxes in the General Circulation and their Parameterization  

Science Conference Proceedings (OSTI)

The effect of eddy momentum fluxes on the general circulation is investigated with the aid of perpetual January simulations with a two-dimensional, zonally averaged model. Sensitivity experiments with this model show that the vertical eddy flux ...

Peter H. Stone; Mao-Sung Yao

1987-12-01T23:59:59.000Z

219

Simulation of large supply chains: simulation of waste processing, transportation, and disposal operations  

Science Conference Proceedings (OSTI)

In response to the accelerated cleanup goals of the Department of Energy, Sandia National Laboratory (Sandia) has developed and utilized a number of simulation models to represent the processing, transportation, and disposal of radioactive waste. Sandia, ...

Janis Trone; Angela Guerin; Amber D. Clay

2000-12-01T23:59:59.000Z

220

Convective Modifications of a Geostrophic Eddy Field  

Science Conference Proceedings (OSTI)

Ocean convection often occurs in regions of mesoscale eddy activity, where convective mixing and geostrophic eddy dynamics interact. The authors examine the interactions between a group of geostrophic eddies and convective mixing induced by ...

Sonya Legg; James C. McWilliams

2001-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Life Cycles of Moist Baroclinic Eddies  

Science Conference Proceedings (OSTI)

The interaction between moisture and baroclinic eddies was examined through eddy life-cycle experiments using a global, primitive equation model. How condensation affects the structural evolution of eddies, their fluxes of heat, moisture, and ...

William J. Gutowski Jr.; Lee E. Branscome; Douglas A. Stewart

1992-02-01T23:59:59.000Z

222

When Are Eddy Tracer Fluxes Directed Downgradient?  

Science Conference Proceedings (OSTI)

The mechanisms controlling the direction of eddy tracer fluxes are examined using eddy-resolving isopycnic experiments for a cyclic zonal channel. Eddy fluxes are directed downgradient on average when either (i) there is a Lagrangian increase in ...

Chris Wilson; Richard G. Williams

2006-02-01T23:59:59.000Z

223

Fission of Single and Multiple Eddies  

Science Conference Proceedings (OSTI)

The analytical results for the splitting conditions of isolated barotropic eddies and the associated final equilibrium state are extended to: 1) nonlinear baroclinic eddies; 2) a group of four nonlinear closely packed eddies, two of which are ...

Doron Nof

1991-01-01T23:59:59.000Z

224

Development of models and methods for the molecular simulation of large systems and molecules  

E-Print Network (OSTI)

The most important factor for quantitative results in molecular dynamics simulation are well developed force fields and models. In the present work, the development of new models and the usage of force fields from the literature in large systems are presented. Both tasks lead to time consuming simulations that require massively parallel high performance computing. In the present work, new models for carbon dioxide and cyclohexanolare discussed and a new method for the model development is introduced. Force fields and models for the simulation of PNIPAAm hydrogel in pure water and sodium chloride solution are tested and verified and applied to the simulation of nucleation processes.

Walter, Jonathan; Horsch, Martin; Vrabec, Jadran; Hasse, Hans

2010-01-01T23:59:59.000Z

225

NAMD - The Engine for Large-Scale Classical MD Simulations of Biomolecular  

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

NAMD NAMD NAMD - The Engine for Large-Scale Classical MD Simulations of Biomolecular Systems Based on a Polarizable Force Field PI Name: Benoit Roux PI Email: roux@uchicago.edu Institution: Argonne National Laboratory & University of Chicago Allocation Program: ESP Allocation Hours at ALCF: 80 Million Year: 2010 to 2013 Research Domain: Biological Sciences Biology, at the atomic and molecular level, is governed by complex interactions involving a large number of key constituents, including water, ions, proteins, nucleic acids, and lipid membranes. The goal of this project is to develop new technologies to simulate virtual models of biomolecular systems with an unprecedented accuracy. Large-scale molecular dynamics (MD) simulations based on atomic models play an increasingly

226

Simulation of an Electrostatic Energy Harvester at Large Amplitude Narrow and Wide Band Vibrations  

E-Print Network (OSTI)

An electrostatic in-plane overlap varying energy harvester is modeled and simulated using a circuit simulator. Both linear and nonlinear models are investigated. The nonlinear model includes mechanical stoppers at the displacement extremes. Large amplitude excitation signals, both narrow and wide band, are used to emulate environmental vibrations. Nonlinear behavior is significant at large displacement due to the impact on mechanical stoppers. For a sinusoidal excitation the mechanical stoppers cause the output power to flatten and weakly decrease. For a wide band excitation, the output power first increases linearly with the power spectral density of the input signal, then grows slower than linearly.

Tvedt, Lars Geir Whist; Halvorsen, Einar

2008-01-01T23:59:59.000Z

227

Large scale test simulations using the Virtual Environment for Test Optimization (VETO)  

SciTech Connect

The Virtual Environment for Test Optimization (VETO) is a set of simulation tools under development at Sandia to enable test engineers to do computer simulations of tests. The tool set utilizes analysis codes and test information to optimize design parameters and to provide an accurate model of the test environment which aides in the maximization of test performance, training, and safety. Previous VETO effort has included the development of two structural dynamics simulation modules that provide design and optimization tools for modal and vibration testing. These modules have allowed test engineers to model and simulate complex laboratory testing, to evaluate dynamic response behavior, and to investigate system testability. Further development of the VETO tool set will address the accurate modeling of large scale field test environments at Sandia. These field test environments provide weapon system certification capabilities and have different simulation requirements than those of laboratory testing.

Klenke, S.E.; Heffelfinger, S.R.; Bell, H.J.; Shierling, C.L.

1997-10-01T23:59:59.000Z

228

In-situ sampling of a large-scale particle simulation for interactive visualization and analysis  

SciTech Connect

We propose storing a random sampling of data from large scale particle simulations, such as the Roadrunner Universe MC{sup 3} cosmological simulation, to be used for interactive post-analysis and visualization. Simulation data generation rates will continue to be far greater than storage bandwidth rates and other limiting technologies by many orders of magnitude. This implies that only a very small fraction of data generated by the simulation can ever be stored and subsequently post-analyzed. The limiting technology in this situation is analogous to the problem in many population surveys: there aren't enough human resources to query a large population. To cope with the lack of resources, statistical sampling techniques are used to create a representative data set of a large population. Mirroring that situation, we propose to store a simulation-time random sampling of the particle data to cope with the bOlllenecks and support interactive, exploratory post-analysis. The particle samples are immediately stored in a level-ol-detail format for post-visualization and analysis, which amortizes the cost of post-processing for interactive visualization. Additionally, we incorporate a system for recording and visualizing sample approximation error information for confidence and importance highlighting.

Woodring, Jonathan L [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Heitmann, Katrin [Los Alamos National Laboratory

2010-12-09T23:59:59.000Z

229

An analytical framework for particle and volume data of large-scale combustion simulations  

Science Conference Proceedings (OSTI)

This paper presents a framework to enable parallel data analyses and visualizations that combine both Lagrangian particle data and Eulerian field data of large-scale combustion simulations. Our framework is characterized by a new range query based design ... Keywords: data transformation and representation, feature extraction and tracking, scalability issues

Franz Sauer, Hongfeng Yu, Kwan-Liu Ma

2013-11-01T23:59:59.000Z

230

Life Cycle of Numerically Simulated Shallow Cumulus Clouds. Part II: Mixing Dynamics  

Science Conference Proceedings (OSTI)

This paper is the second in a two-part series in which life cycles of six numerically simulated shallow cumulus clouds are systematically examined. The six clouds, selected from a single realization of a large-eddy simulation, grow as a series of ...

Ming Zhao; Philip H. Austin

2005-05-01T23:59:59.000Z

231

Effects of Sea-Salt Aerosols on Precipitation in Simulations of Shallow Cumulus  

Science Conference Proceedings (OSTI)

A suite of large-eddy simulations with size-resolving microphysical processes was performed in order to assess effects of sea-salt aerosols on precipitation process in trade cumulus. Simulations based on observations from the Rain in Cumulus over ...

Yefim L. Kogan; David B. Mechem; Kityan Choi

2012-02-01T23:59:59.000Z

232

Meridional Motion of Mixing Eddies  

Science Conference Proceedings (OSTI)

A two-layer model of anticyclonic eddy propagation including the effects of diapycnal mixing is presented. The lower layer is assumed to be of finite volume, whereas the upper layer is infinite in horizontal extent, and its dynamics are ...

N. Robb McDonald; David N. Straub

1995-05-01T23:59:59.000Z

233

The Eddy-Driven Thermocline  

Science Conference Proceedings (OSTI)

The role of baroclinic eddies in transferring thermal gradients laterally, and thus determining the stratification of the ocean, is examined. The hypothesis is that the density differences imposed at the surface by differential heating are a ...

Paola Cessi; Maurizio Fantini

2004-12-01T23:59:59.000Z

234

NONDESTRUCTIVE EDDY CURRENT TESTING  

DOE Patents (OSTI)

An eddy current testing device is described for measuring metal continuity independent of probe-to-sample spacing. An inductance would test probe is made a leg of a variable impedance bridge and the bridge is balanced with the probe away from the sample. An a-c signal is applied across the input terminals of the bridge circuit. As the probe is brought into proximity with the metal sample, the resulting impedance change in the probe gives an output signal from the bridge whose phase angle is proportional to the sample continuity and amplitude is proportional to the probe-tosample spacing. The output signal from the bridge is applied to a compensating network where, responsive to amplitude changes from the bridge output signal, a constant phased voltage output is maintained when the sample is continuous regardless of probe-to-sample spacing. A phase meter calibrated to read changes in resistivity of the metal sample measures the phase shift between the output of the compensating network and the original a-c signal applied to the bridge.

Renken, C.J. Jr.

1961-05-23T23:59:59.000Z

235

Eddy current transducing system  

SciTech Connect

In a program funded by the Office of Energy Related Inventions of the Department of Energy, Vatell Corporation developed a prototype Turbine Blade Condition Monitor. This microcomputer-based system was tested to determine its performance in measuring individual blade clearance and time of arrival on a Pratt Whitney (Canada) JT15D jet engine. A Vatell eddy-current sensor mounted in the housing of the engine at mid-chord of the N1 first stage provided the signals. The N1 first stage is a 31 in. diameter fan with 28 titanium blades, operating over a speed range of approximately 7000 to 14,000 rpm. Tests showed that the monitoring system transduced blade clearances with a precision of .0001 in., simultaneously indicating times of arrival within 0.1 microseconds, equivalent to a pitch of .0015 in. Patterns of blade clearances and timing variations were observed for various engine operating conditions, and the clearance and time of arrival signatures'' of the fan stage were recorded. Manufacturing variations in blade pitch were readily detected, as were indications of blade and hub vibration. The report contains a detailed description of the development program, examples of waveforms and recorded data, circuit diagrams, software, setup and operating procedures for the monitoring system. 66 refs.

1991-09-13T23:59:59.000Z

236

Eddy-Induced Particle Dispersion in the Near-Surface North Atlantic  

Science Conference Proceedings (OSTI)

This study investigates the anisotropic properties of the eddy-induced material transport in the near-surface North Atlantic from two independent datasets, one simulated from the sea surface height altimetry and one derived from real-ocean surface ...

Irina I. Rypina; Igor Kamenkovich; Pavel Berloff; Lawrence J. Pratt

2012-12-01T23:59:59.000Z

237

Response of a Strongly Eddying Global Ocean to North Atlantic Freshwater Perturbations  

Science Conference Proceedings (OSTI)

The strongly eddying version of the Parallel Ocean Program (POP) is used in two 45-year simulations to investigate the response of the Atlantic Meridional Overturning Circulation (AMOC) to strongly enhanced freshwater input due to Greenland ...

Matthijs den Toom; Henk A. Dijkstra; Wilbert Weijer; Matthew W. Hecht; Mathew E. Maltrud; Erik van Sebille

238

NV Energy Large-Scale Photovoltaic Integration Study: Intra-Hour Dispatch and AGC Simulation  

SciTech Connect

The uncertainty and variability with photovoltaic (PV) generation make it very challenging to balance power system generation and load, especially under high penetration cases. Higher reserve requirements and more cycling of conventional generators are generally anticipated for large-scale PV integration. However, whether the existing generation fleet is flexible enough to handle the variations and how well the system can maintain its control performance are difficult to predict. The goal of this project is to develop a software program that can perform intra-hour dispatch and automatic generation control (AGC) simulation, by which the balancing operations of a system can be simulated to answer the questions posed above. The simulator, named Electric System Intra-Hour Operation Simulator (ESIOS), uses the NV Energy southern system as a study case, and models the systems generator configurations, AGC functions, and operator actions to balance system generation and load. Actual dispatch of AGC generators and control performance under various PV penetration levels can be predicted by running ESIOS. With data about the load, generation, and generator characteristics, ESIOS can perform similar simulations and assess variable generation integration impacts for other systems as well. This report describes the design of the simulator and presents the study results showing the PV impacts on NV Energy real-time operations.

Lu, Shuai; Etingov, Pavel V.; Meng, Da; Guo, Xinxin; Jin, Chunlian; Samaan, Nader A.

2013-01-02T23:59:59.000Z

239

Data Analysis and Visualization Environments for Large Scale Simulation as presented by  

E-Print Network (OSTI)

Sandia National Laboratories has been researching data analysis and visualization through several approaches. They have been research partners on several large open source projects as well as commercial and classified projects. Current research is centered around cluster solutions based largely on consumer hardware. Constantine Pavlakos outlined the historical research and the motivating problems behind the modern visualization efforts underway at SNL. The basic problem is that the data produced by large scale simulations is far too large to be handled sloppily. The data sets Mr. Pavlakos presented as examples were often on the order of half a petabyte in size. To address many of the issues associated with data sets of this scale Sandia has pursued cluster based solutions. I have a personal interest in this solution, and have experimented with the power wall that the UNM CS department

Constantine Pavlakos; Christopher E. Davis

2004-01-01T23:59:59.000Z

240

Thermal plant outages in a large hydro-thermal power supply system a method in probabilistic simulation  

Science Conference Proceedings (OSTI)

The advent of large computers has made a significant impact upon decision theory with their ability to generate a large number of simulations within a relatively short period of time. Better estimates of a system's capabilities and parameters can be ...

Charles W. Eastwood

1980-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Nondestructive Evaluation: CIVA Software Comparisons for Eddy Current and Radiographic Techniques  

Science Conference Proceedings (OSTI)

This report documents the status of an independent validation of the French Alternative Energies and Atomic Energy Commissions (CEAs) CIVA1 simulation software for eddy current and radiographic inspections performed by the Electric Power Research Institute (EPRI). A general overview of the CIVA program simulation capability and process is presented with respect to eddy current testing and radiographic testing, along with some comparisons between experimental and ...

2012-11-29T23:59:59.000Z

242

Decadal Sea Level Variability in the South Pacific in a Global Eddy-Resolving Ocean Model Hindcast  

Science Conference Proceedings (OSTI)

Sea level variability and related oceanic changes in the South Pacific from 1970 to 2003 are investigated using a hindcast simulation of an eddy-resolving ocean general circulation model (OGCM) for the Earth Simulator (OFES), along with sea level ...

Yoshi N. Sasaki; Shoshiro Minobe; Niklas Schneider; Takashi Kagimoto; Masami Nonaka; Hideharu Sasaki

2008-08-01T23:59:59.000Z

243

Simulation study of beam-beam effects in ion beams with large space charge tuneshift  

Science Conference Proceedings (OSTI)

During low-energy operations with gold-gold collisions at 3.85 GeV beam energy, significant beam lifetime reductions have been observed due to the beam-beam interaction in the presence of large space charge tuneshifts. These beam-beam tuneshift parameters were about an order of magnitude smaller than during regular high energy operations. To get a better understanding of this effect, simulations have been performed. Recent results are presented.

Montag C.

2012-05-20T23:59:59.000Z

244

High-Resolution Large-Eddy Simulations of Flow in a Steep Alpine Valley. Part II: Flow Structure and Heat Budgets  

Science Conference Proceedings (OSTI)

This paper analyzes the three-dimensional flow structure and the heat budget in a typical medium-sized and steep Alpine valleythe Riviera Valley in southern Switzerland. Aircraft measurements from the Mesoscale Alpine Programme (MAP)-Riviera ...

Andreas P. Weigel; Fotini K. Chow; Mathias W. Rotach; Robert L. Street; Ming Xue

2006-01-01T23:59:59.000Z

245

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

246

Mesh-free simulations of shear banding in large deformation Shaofan Li, Wei Hao, Wing Kam Liu *  

E-Print Network (OSTI)

Mesh-free simulations of shear banding in large deformation Shaofan Li, Wei Hao, Wing Kam Liu Mesh-free approximation is used in numerical simulations of strain localization under large deformation. An explicit displacement based mesh-free formulation is used in both two-dimensional and three

Li, Shaofan

247

Dynamics of Potential Vorticity Fronts and Eddy Detachment  

Science Conference Proceedings (OSTI)

The formation and detachment of quasi-geostrophic eddies in a 1 layer jet is studied using a piecewise uniform potential vorticity model. A vorticity front separates the two pieces, and thus the jet has cusplike character. The evolution of large ...

L. J. Pratt; Melvin E. Stern

1986-06-01T23:59:59.000Z

248

Transient Eddies and the Seasonal Mean Rotational Flow  

Science Conference Proceedings (OSTI)

Virtually all investigations of transient-eddy effects on the large-scale mean vorticity start from the premise that only the rotational transient motion need be considered. In this paper, the seasonal mean vorticity balance at 250 mb is examined,...

Brian J. Hoskins; Prashant D. Sardeshmukh

1987-01-01T23:59:59.000Z

249

Atmospherically Forced Eddies in the Northeast Pacific  

Science Conference Proceedings (OSTI)

In the northeast Pacific eddies are observed in the salinity and, to a lesser extent, in the thermal anomalies. In particular, a pronounced eddy is frequently observed a few hundred kilometers west of Sitka, Alaska, latitude 57N. This paper ...

A. J. Willmott; L. A. Mysak

1980-11-01T23:59:59.000Z

250

Observations of Irminger Sea Anticyclonic Eddies  

Science Conference Proceedings (OSTI)

Mesoscale anticyclonic eddies in the Irminger Sea are observed using a mooring and a glider. Between 2002 and 2009, the mooring observed 53 anticyclones. Using a kinematic model, objective estimates of eddy length scales and velocity structure are ...

Xue Fan; Uwe Send; Pierre Testor; Johannes Karstensen; Pascale Lherminier

2013-04-01T23:59:59.000Z

251

On a Recent Parameterization of Mesoscale Eddies  

Science Conference Proceedings (OSTI)

A recent parameterization of mesoscale eddies by Gent and McWilliams (GMc) represents their effects as advective and diffusive fluxes along isopycnals. The form chosen for the added transport velocity due to eddies flattens isopycnals as in ...

Amit Tandon; Chris Garrett

1996-03-01T23:59:59.000Z

252

Baroclinic Eddy Equilibration under Specified Seasonal Forcing  

Science Conference Proceedings (OSTI)

Baroclinic eddy equilibration under a Northern Hemispherelike seasonal forcing is studied using a modified multilayer quasigeostrophic channel model to investigate the widely used quick baroclinic eddy equilibration assumption and to ...

Yang Zhang; Peter H. Stone

2010-08-01T23:59:59.000Z

253

P.: Quick simulation methods for estimating the unreliability of regenerative models of large highly reliable systems  

E-Print Network (OSTI)

We investigate fast simulation techniques for estimating the unreliability in large Markovian models of highly reliable systems for which analytical0numerical techniques are difficult to apply+ We first show mathematically that for small time horizons, the relative simulation error, when using the importance sampling techniques of failure biasing and forcing, remains bounded as component failure rates tend to zero+ This is in contrast to naive simulation where the relative error tends to infinity+ For large time horizons where these techniques are not efficient, we use the approach of first bounding the unreliability in terms of regenerative-cycle-based measures and then estimating the regenerative-cycle-based measures using importance sampling; the latter can be done very efficiently+ We first use bounds developed in the literature for the asymptotic distribution of the time to hitting a rare set in regenerative systems+ However, these bounds are close to the unreliability only for a certain range of time horizons+ We develop new bounds that make use of the special structure of the systems that we consider and are close to the unreliability for a much wider range of time horizons+ These techniques extend to non-Markovian, highly reliable systems as long as the regenerative structure is preserved+ 2004 Cambridge University Press 0269-9648004 $16+00 339340 M. K. Nakayama and P. Shahabuddin 1.

Marvin K. Nakayama; Perwez Shahabuddin

2004-01-01T23:59:59.000Z

254

Simulating the power consumption of large-scale sensor network applications  

E-Print Network (OSTI)

Developing sensor network applications demands a new set of tools to aid programmers. A number of simulation environments have been developed that provide varying degrees of scalability, realism, and detail for understanding the behavior of sensor networks. To date, however, none of these tools have addressed one of the most important aspects of sensor application design: that of power consumption. While simple approximations of overall power usage can be derived from estimates of node duty cycle and communication rates, these techniques often fail to capture the detailed, low-level energy requirements of the CPU, radio, sensors, and other peripherals. In this paper, we present PowerTOSSIM, a scalable simulation environment for wireless sensor networks that provides an accurate, per-node estimate of power consumption. PowerTOSSIM is an extension to TOSSIM, an event-driven simulation environment for TinyOS applications. In PowerTOSSIM, TinyOS components corresponding to specific hardware peripherals (such as the radio, EEPROM, LEDs, and so forth) are instrumented to obtain a trace of each devices activity during the simulation run. PowerTOSSIM employs a novel code-transformation technique to estimate the number of CPU cycles executed by each node, eliminating the need for expensive instruction-level simulation of sensor nodes. PowerTOSSIM includes a detailed model of hardware energy consumption based on the Mica2 sensor node platform. Through instrumentation of actual sensor nodes, we demonstrate that PowerTOSSIM provides accurate estimation of power consumption for a range of applications and scales to support very large simulations.

Victor Shnayder; Mark Hempstead; Bor-rong Chen; Geoff Werner Allen; Matt Welsh

2004-01-01T23:59:59.000Z

255

A GIS/Simulation Framework for Assessing Change in Water Yield over Large Spatial Scales  

DOE Green Energy (OSTI)

Recent legislation to,initiate vegetation management in the Central Sierra hydrologic region of California includes a focus on corresponding changes in water yield. This served as the impetus for developing a combined geographic information system (GIS) and simulation assessment framework. Using the existing vegetation density condition, together with proposed rules for thinning to reduce fire risk, a set of simulation model inputs were generated for examining the impact of the thinning scenario on water yield. The approach allows results to be expressed as the mean and standard deviation of change in water yield for each 1 km2 map cell that is treated. Values for groups of cells are aggregated for typical watershed units using area-weighted averaging. Wet, dry and average precipitation years were simulated over a large region. Where snow plays an important role in hydrologic processes, the simulated change in water yield was less than 0.5% of expected annual runoff for a typical water shed. Such small changes would be undetectable in the field using conventional stream flow analysis. These results suggest that use of water yield increases to help justify forest-thinning activities or offset their cost will be difficult.

Graham, R.; Hargrove, W.W.; Huff, D.D.; Nikolov, N.; Tharp, M.L.

1999-11-13T23:59:59.000Z

256

Standing Eddies in the Meridional Overturning Circulation  

Science Conference Proceedings (OSTI)

The role of standing eddies for the meridional overturning circulation (MOC) is discussed. The time-mean isopycnal meridional streamfunction is decomposed into a time- and zonal-mean part, a standing-eddy part, and a transient-eddy part. It turns ...

Jan Viebahn; Carsten Eden

2012-09-01T23:59:59.000Z

257

Large-scale three-dimensional geothermal reservoir simulation on PCs  

DOE Green Energy (OSTI)

TOUGH2, Lawrence Berkeley Laboratory`s general purpose simulator for mass and heat flow and transport was enhanced with the addition of a set of preconditioned conjugate gradient solvers and ported to a PC. The code was applied to a number of large 3-D geothermal reservoir problems with up to 10,000 grid blocks. Four test problems were investigated. The first two involved a single-phase liquid system, and a two-phase system with regular Cartesian grids. The last two involved a two-phase field problem with irregular gridding with production from and injection into a single porosity reservoir, and a fractured reservoir. The code modifications to TOUGH2 and its setup in the PC environment are described. Algorithms suitable for solving large matrices that are generally non-symmetric and non-positive definite are reviewed. Computational work per time step and CPU time requirements are reported as function of problem size. The excessive execution time and storage requirements of the direct solver in TOUGH2 limits the size of manageable 3-D reservoir problems to a few hundred grid blocks. The conjugate gradient solvers significantly reduced the execution time and storage requirements making possible the execution of considerably larger problems (10,000 + grid blocks). It is concluded that the current PCs provide an economical platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers.

Antunez, E.; Moridis, G.; Pruess, K.

1994-01-01T23:59:59.000Z

258

Large-scale three-dimensional geothermal reservoir simulation on PCs  

Science Conference Proceedings (OSTI)

TOUGH2, Lawrence Berkeley Laboratory's general purpose simulator for mass and heat flow and transport was enhanced with the addition of a set of preconditioned conjugate gradient solvers and ported to a PC. The code was applied to a number of large 3-D geothermal reservoir problems with up to 10,000 grid blocks. Four test problems were investigated. The first two involved a single-phase liquid system, and a two-phase system with regular Cartesian grids. The last two involved a two-phase field problem with irregular gridding with production from and injection into a single porosity reservoir, and a fractured reservoir. The code modifications to TOUGH2 and its setup in the PC environment are described. Algorithms suitable for solving large matrices that are generally non-symmetric and non-positive definite are reviewed. Computational work per time step and CPU time requirements are reported as function of problem size. The excessive execution time and storage requirements of the direct solver in TOUGH2 limits the size of manageable 3-D reservoir problems to a few hundred grid blocks. The conjugate gradient solvers significantly reduced the execution time and storage requirements making possible the execution of considerably larger problems (10,000+ grid blocks). It is concluded that the current PCs provide an economical platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers.

Antunez, Emilio; Moridis, George; Pruess, Karsten

1994-01-20T23:59:59.000Z

259

Large-scale three-dimensional geothermal reservoir simulation on small computer systems  

DOE Green Energy (OSTI)

The performance of TOUGH2, Lawrence Berkeley Laboratory`s general purpose simulator for mass and heat flow and transport enhanced with the addition of a set of preconditioned conjugate gradient solvers, was tested on three PCs (486-33, 486-66, Pentium-90), a MacIntosh Quadra 800, and a workstation IBM RISC 6000. A two-phase, single porosity, 3-D geothermal reservoir model with 1,411 irregular grid blocks, with production from and injection into the reservoir was used as the test model. The code modifications to TOUGH2 and its setup in each machine environment are described. Computational work per time step and CPU time requirements are reported for each of the machines used. It is concluded that the current PCs provide the best price/performance platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers and high-end workstations.

Antunez, E.; Moridis, G.; Pruess, K.

1995-05-01T23:59:59.000Z

260

The Life Cycle of Baroclinic Eddies in a Storm Track Environment  

Science Conference Proceedings (OSTI)

The life cycle of baroclinic eddies in a controlled storm track environment has been examined by means of long model integrations on a hemisphere. A time-lagged regression that captures disturbances with large meridional velocities has been ...

Isidoro Orlanski; Brian Gross

2000-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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 Development of the Barotropic Radiation Field of an Eddy over a Slope  

Science Conference Proceedings (OSTI)

Low-frequency current measurements near the shelf break south of Nova Scotia indicate that the presence of topographic waves on the continental slope, and rise is associated with large-scale shoreward excursions and formation of eddies by the ...

John P. Louis; Peter C. Smith

1982-01-01T23:59:59.000Z

262

Eddy-Train Encounters with a Continental Boundary: A South Atlantic Case Study  

Science Conference Proceedings (OSTI)

Satellite altimetry suggests that large anticyclonic eddies (rings) originating from the Agulhas Current retroflection occasionally make their way across the entire South Atlantic Ocean. What happens when these rings encounter a western boundary ...

Jos L. L. Azevedo; Doron Nof; Mauricio M. Mata

2012-09-01T23:59:59.000Z

263

Solving Large Sparse Linear Systems in End-to-end Accelerator Structure Simulations  

Science Conference Proceedings (OSTI)

This paper presents a case study of solving very large sparse linear systems in end-to-end accelerator structure simulations. Both direct solvers and iterative solvers are investigated. A parallel multilevel preconditioner based on hierarchical finite element basis functions is considered and has been implemented to accelerate the convergence of iterative solvers. A linear system with matrix size 93,147,736 and with 3,964,961,944 non-zeros from 3D electromagnetic finite element discretization has been solved in less than 8 minutes with 1024 CPUs on the NERSC IBM SP. The resource utilization as well as the application performance for these solvers is discussed.

Lee, L

2004-01-23T23:59:59.000Z

264

Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame  

SciTech Connect

Knowledge of eddy currents in the vacuum vessel walls and nearby conducting support structures can significantly contribute to the accuracy of Magnetohydrodynamics (MHD) equilibrium reconstruction in toroidal plasmas. Moreover, the magnetic fields produced by the eddy currents could generate error fields that may give rise to islands at rational surfaces or cause field lines to become chaotic. In the Compact Toroidal Hybrid (CTH) device (R0 = 0.75 m, a = 0.29 m, B ? 0.7 T), the primary driver of the eddy currents during the plasma discharge is the changing flux of the ohmic heating transformer. Electromagnetic simulations are used to calculate eddy current paths and profile in the vacuum vessel and in the coil frame pieces with known time dependent currents in the ohmic heating coils. MAXWELL and SPARK codes were used for the Electromagnetic modeling and simulation. MAXWELL code was used for detailed 3D finite-element analysis of the eddy currents in the structures. SPARK code was used to calculate the eddy currents in the structures as modeled with shell/surface elements, with each element representing a current loop. In both cases current filaments representing the eddy currents were prepared for input into VMEC code for MHD equilibrium reconstruction of the plasma discharge. __________________________________________________

A. Zolfaghari, A. Brooks, A. Michaels, J. Hanson, and G. Hartwell

2012-09-25T23:59:59.000Z

265

Loop Current and Deep Eddies  

Science Conference Proceedings (OSTI)

In contrast to the Loop Current and rings, much less is known about deep eddies (deeper than 1000 m) of the Gulf of Mexico. In this paper, results from a high-resolution numerical model of the Gulf are analyzed to explain their origin and how ...

L-Y. Oey

2008-07-01T23:59:59.000Z

266

A Note on Owens' Mesoscale Eddy Simulation  

Science Conference Proceedings (OSTI)

By means of the statistical theory of turbulence, we analyze the proposal advanced recently by Owens (1979) that the small-scale Eulerian acceleration is accurately predicted by a Taylor frozen field hypothesis. We show that Owens' rms ...

Jackson R. Herring

1980-05-01T23:59:59.000Z

267

Testing of Large-Scale ICV Glasses with Hanford LAW Simulant  

SciTech Connect

Preliminary glass compositions for immobilizing Hanford low-activity waste (LAW) by the in-container vitrification (ICV) process were initially fabricated at crucible- and engineering-scale, including simulants and actual (radioactive) LAW. Glasses were characterized for vapor hydration test (VHT) and product consistency test (PCT) responses and crystallinity (both quenched and slow-cooled samples). Selected glasses were tested for toxicity characteristic leach procedure (TCLP) responses, viscosity, and electrical conductivity. This testing showed that glasses with LAW loading of 20 mass% can be made readily and meet all product constraints by a far margin. Glasses with over 22 mass% Na2O can be made to meet all other product quality and process constraints. Large-scale testing was performed at the AMEC, Geomelt Division facility in Richland. Three tests were conducted using simulated LAW with increasing loadings of 12, 17, and 20 mass% Na2O. Glass samples were taken from the test products in a manner to represent the full expected range of product performance. These samples were characterized for composition, density, crystalline and non-crystalline phase assemblage, and durability using the VHT, PCT, and TCLP tests. The results, presented in this report, show that the AMEC ICV product with meets all waste form requirements with a large margin. These results provide strong evidence that the Hanford LAW can be successfully vitrified by the ICV technology and can meet all the constraints related to product quality. The economic feasibility of the ICV technology can be further enhanced by subsequent optimization.

Hrma, Pavel R.; Kim, Dong-Sang; Vienna, John D.; Matyas, Josef; Smith, Donald E.; Schweiger, Michael J.; Yeager, John D.

2005-03-01T23:59:59.000Z

268

Eddy-Current Instruments  

Science Conference Proceedings (OSTI)

...system is an induction bridge, in which the power signal is transformer coupled into an inspection coil and a reference coil. In addition, the entire inductance-balance system is placed in the probe, as shown in Fig. 12 . The probe consists of a large transmitter (or driver) coil and two small...

269

A new wall-shear stress model for atmospheric boundary layer simulations  

Science Conference Proceedings (OSTI)

A new wall-shear stress model to be used as wall-boundary condition for Large Eddy Simulations of the Atmospheric Boundary Layer is proposed. The new model computes the wall shear stress and the vertical derivatives of the streamwise velocity ...

Marcus Hultmark; Marc Calaf; Marc B. Parlange

270

The Wind-driven Circulation: Quasi-geostrophic Simulations and Theory for Nonsymmetric Winds  

Science Conference Proceedings (OSTI)

Simulations of the wind-driven Ocean circulation, carded out with an eddy-resolving quasi-geostrophic numerical model, and symmetric, idealized wind forcing have a large-scale structure that is predicted wen by the steady nonlinear theory of ...

Peter B. Rhines; Richard Schopp

1991-09-01T23:59:59.000Z

271

Direct Numerical Simulation of Evaporative Cooling at the Lateral Boundary of Shallow Cumulus Clouds  

Science Conference Proceedings (OSTI)

This study investigates the dynamics of the subsiding shell at the lateral boundary of cumulus clouds, focusing on the role of evaporative cooling. Since the size of this shell is well below what large-eddy simulations can resolve, the authors ...

Dick Abma; Thijs Heus; Juan Pedro Mellado

2013-07-01T23:59:59.000Z

272

Simulation of a Stratocumulus-Topped Planetary Boundary Layer: Intercomparison among Different Numerical Codes  

Science Conference Proceedings (OSTI)

This paper reports an intercomparison study of a stratocumulus-topped planetary boundary layer (PBL) generated from ten 3D large eddy simulation (LES) codes and four 2D cloud-resolving models (CRMs). These models vary in the numerics, the ...

C-H. Moeng; W. R. Cotton; B. Stevens; C. Bretherton; H. A. Rand; A. Chlond; M. Khairoutdinov; S. Krueger; W. S. Lewellen; M. K. MacVean; J. R. M. Pasquier; A. P. Siebesma; R. I. Sykes

1996-02-01T23:59:59.000Z

273

Remote field eddy current inspection  

SciTech Connect

The Remote Field Eddy Current (RFEC) technique uses an internal probe to inspect conducting tubes nondestructively. A coaxial solenoidal exciter, energized with low frequency AC, and detector coils near the inside of the pipe wall are separated by about two pipe diameters to obtain through wall transmission and equal sensitivity to defects on the outside or inside of the pipe wall. Calculation methods are outlined and the voltage plane polar plot signal representation for defect measurement is described. Slit defect interactions in ferromagnetic and non-ferromagnetic tubes are discussed. Defect-induced anomalous fields are interpreted in terms of anomalous source eddy current and missing magnetization defect models. The use of computer animations to represent the time variations of high resolution field measurements and calculations is described.

Atherton, D.L. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Physics

1995-11-01T23:59:59.000Z

274

Nek5000 Ready to Use after Simulations of Important Pipe Flow Benchmark |  

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

Nek5000 Ready to Use after Simulations of Important Pipe Flow Nek5000 Ready to Use after Simulations of Important Pipe Flow Benchmark Nek5000 Ready to Use after Simulations of Important Pipe Flow Benchmark January 29, 2013 - 1:42pm Addthis Velocity magnitude in MATiS-H spacer grid with swirl-type vanes. Velocity magnitude in MATiS-H spacer grid with swirl-type vanes. As part of the on-going Nek5000 validation efforts, a series of large eddy simulations (LES) have been performed for thermal stratification in a pipe. Results were in good agreement with the experiment and the simulation data has provided insight into the physics of the flow. An additional series of simulations of the OECD-NEA MATiS-H benchmark has also been completed using intermediate- fidelity modeling approaches, such as k-epsilon, k-omega shear stress transport, and ID detached eddy simulation, as well as one

275

Large-scale Nanostructure Simulations from X-ray Scattering Data On Graphics Processor Clusters  

Science Conference Proceedings (OSTI)

X-ray scattering is a valuable tool for measuring the structural properties of materialsused in the design and fabrication of energy-relevant nanodevices (e.g., photovoltaic, energy storage, battery, fuel, and carbon capture andsequestration devices) that are key to the reduction of carbon emissions. Although today's ultra-fast X-ray scattering detectors can provide tremendousinformation on the structural properties of materials, a primary challenge remains in the analyses of the resulting data. We are developing novelhigh-performance computing algorithms, codes, and software tools for the analyses of X-ray scattering data. In this paper we describe two such HPCalgorithm advances. Firstly, we have implemented a flexible and highly efficient Grazing Incidence Small Angle Scattering (GISAXS) simulation code based on theDistorted Wave Born Approximation (DWBA) theory with C++/CUDA/MPI on a cluster of GPUs. Our code can compute the scattered light intensity from any givensample in all directions of space; thus allowing full construction of the GISAXS pattern. Preliminary tests on a single GPU show speedups over 125x compared tothe sequential code, and almost linear speedup when executing across a GPU cluster with 42 nodes, resulting in an additional 40x speedup compared to usingone GPU node. Secondly, for the structural fitting problems in inverse modeling, we have implemented a Reverse Monte Carlo simulation algorithm with C++/CUDAusing one GPU. Since there are large numbers of parameters for fitting in the in X-ray scattering simulation model, the earlier single CPU code required weeks ofruntime. Deploying the AccelerEyes Jacket/Matlab wrapper to use GPU gave around 100x speedup over the pure CPU code. Our further C++/CUDA optimization deliveredan additional 9x speedup.

Sarje, Abhinav; Pien, Jack; Li, Xiaoye; Chan, Elaine; Chourou, Slim; Hexemer, Alexander; Scholz, Arthur; Kramer, Edward

2012-01-15T23:59:59.000Z

276

Thermal Performance Evaluation of Attic Radiant Barrier Systems Using the Large Scale Climate Simulator (LSCS)  

SciTech Connect

Application of radiant barriers and low-emittance surface coatings in residential building attics can significantly reduce conditioning loads from heat flow through attic floors. The roofing industry has been developing and using various radiant barrier systems and low-emittance surface coatings to increase energy efficiency in buildings; however, minimal data are available that quantifies the effectiveness of these technologies. This study evaluates performance of various attic radiant barrier systems under simulated summer daytime conditions and nighttime or low solar gain daytime winter conditions using the large scale climate simulator (LSCS). The four attic configurations that were evaluated are 1) no radiant barrier (control), 2) perforated low-e foil laminated oriented strand board (OSB) deck, 3) low-e foil stapled on rafters, and 4) liquid applied low-emittance coating on roof deck and rafters. All test attics used nominal RUS 13 h-ft2- F/Btu (RSI 2.29 m2-K/W) fiberglass batt insulation on attic floor. Results indicate that the three systems with radiant barriers had heat flows through the attic floor during summer daytime condition that were 33%, 50%, and 19% lower than the control, respectively.

Shrestha, Som S [ORNL] [ORNL; Miller, William A [ORNL] [ORNL; Desjarlais, Andre Omer [ORNL] [ORNL

2013-01-01T23:59:59.000Z

277

A scalable messaging system for accelerating discovery from large scale scientific simulations  

SciTech Connect

Emerging scientific and engineering simulations running at scale on leadership-class High End Computing (HEC) environments are producing large volumes of data, which has to be transported and analyzed before any insights can result from these simulations. The complexity and cost (in terms of time and energy) associated with managing and analyzing this data have become significant challenges, and are limiting the impact of these simulations. Recently, data-staging approaches along with in-situ and in-transit analytics have been proposed to address these challenges by offloading I/O and/or moving data processing closer to the data. However, scientists continue to be overwhelmed by the large data volumes and data rates. In this paper we address this latter challenge. Specifically, we propose a highly scalable and low-overhead associative messaging framework that runs on the data staging resources within the HEC platform, and builds on the staging-based online in-situ/in- transit analytics to provide publish/subscribe/notification-type messaging patterns to the scientist. Rather than having to ingest and inspect the data volumes, this messaging system allows scientists to (1) dynamically subscribe to data events of interest, e.g., simple data values or a complex function or simple reduction (max()/min()/avg()) of the data values in a certain region of the application domain is greater/less than a threshold value, or certain spatial/temporal data features or data patterns are detected; (2) define customized in-situ/in-transit actions that are triggered based on the events, such as data visualization or transformation; and (3) get notified when these events occur. The key contribution of this paper is a design and implementation that can support such a messaging abstraction at scale on high- end computing (HEC) systems with minimal overheads. We have implemented and deployed the messaging system on the Jaguar Cray XK6 machines at Oak Ridge National Laboratory and the Lonestar system at the Texas Advanced Computing Center (TACC), and we present the experimental performance evaluation using these HEC platforms in the paper.

Jin, Tong [Rutgers University; Zhang, Fan [Rutgers University; Parashar, Manish [Rutgers University; Klasky, Scott A [ORNL; Podhorszki, Norbert [ORNL; Abbasi, Hasan [ORNL

2012-01-01T23:59:59.000Z

278

Effective Eddy Diffusivities Inferred from a Point Release Tracer in an Eddy-Resolving Ocean Model  

Science Conference Proceedings (OSTI)

This study uses tracer experiments in a global eddy-resolving ocean model to examine two diagnostic methods for inferring effective eddy isopycnic diffusivity from point release tracers. The first method is based on the growth rate of the area ...

Mei-Man Lee; A. J. George Nurser; Andrew C. Coward; Beverly A. de Cuevas

2009-04-01T23:59:59.000Z

279

Subthermocline Eddies in the Western Equatorial Pacific as Shown by an Eddy-Resolving OGCM  

Science Conference Proceedings (OSTI)

Sporadic in situ observations have shown evidence that subthermocline eddies exist off the Mindanao coast. These subthermocline eddies are believed to play an important role in the heat, freshwater, and other ocean property transports of the ...

Tzu-Ling Chiang; Tangdong Qu

2013-07-01T23:59:59.000Z

280

Anatomy of Synoptic EddyNAO Interaction through Eddy Structure Decomposition  

Science Conference Proceedings (OSTI)

A method of eddy structure decomposition is proposed to detect how low-frequency flow associated with the North Atlantic Oscillation (NAO) organizes systematically synoptic eddy (SE) activity to generate in-phase and upstream feedbacks. In this ...

Hong-Li Ren; Fei-Fei Jin; Li Gao

2012-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Eddy-Current-Induced Multipole Field Calculations  

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

Eddy-Current-Induced Multipole Field Calculations Eddy-Current-Induced Multipole Field Calculations September 29, 2003 1 Eddy-Current-Induced Multipole Field Calculations Nicholas S. Sereno, Suk H. Kim 1.0 Abstract Time-varying magnetic fields of magnets in booster accelerators induce substantial eddy currents in the vacuum chambers. The eddy currents in turn act to produce various multi- pole fields that act on the beam. These fields must be taken into account when doing a lat- tice design. In the APS booster, the relatively long dipole magnets (3 meters) are linearly ramped to accelerate the injected 325 MeV beam to 7 GeV. Substantial dipole and sextu- pole fields are generated in the elliptical vacuum chamber from the induced eddy currents. In this note, formulas for the induced dipole and sextupole fields are derived for elliptical and rectangular vacuum chambers for a time-varying dipole field. A discussion is given

282

Mesoscale to Submesoscale Transition in the California Current System. Part I: Flow Structure, Eddy Flux, and Observational Tests  

Science Conference Proceedings (OSTI)

In computational simulations of an idealized subtropical eastern boundary upwelling current system, similar to the California Current, a submesoscale transition occurs in the eddy variability as the horizontal grid scale is reduced to O(1) km. ...

X. Capet; J. C. McWilliams; M. J. Molemaker; A. F. Shchepetkin

2008-01-01T23:59:59.000Z

283

Ocean Heat Uptake in Eddying and Non-Eddying Ocean Circulation Models in a Warming Climate  

Science Conference Proceedings (OSTI)

Ocean heat uptake is explored with non-eddying (2), eddy-permitting (0.25), and eddy-resolving (0.125) ocean circulation models in a domain representing the Atlantic basin connected to a southern circumpolar channel with a flat bottom. The ...

Yu Zhang; Geoffrey K. Vallis

2013-10-01T23:59:59.000Z

284

Ocean heat uptake in eddying and non-eddying ocean circulation models in a warming climate  

Science Conference Proceedings (OSTI)

Ocean heat uptake is explored with non-eddying (2), eddy-permitting (0.25) and eddy-resolving (0.125) ocean circulation models in a domain representing the Atlantic basin connected to a southern circumpolar channel with flat bottom. The model ...

Yu Zhang; Geoffrey K. Vallis

285

Updated electron-cloud simulation results for the Large Hadron Collider (LHC)  

E-Print Network (OSTI)

RESULTS FOR THE LARGE HADRON COLLIDER LHC ? M. A. Furman andscreen of the Large Hadron Collider (LHC). We pay particular

Furman, M.A.; Pivi, M.

2001-01-01T23:59:59.000Z

286

Department of Energy Awards Eddy/Lea Regional Commission $300...  

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

EddyLea Regional Commission 300,000 Grant Department of Energy Awards EddyLea Regional Commission 300,000 Grant Department of Energy Awards EddyLea Regional Commission...

287

The Role of Stationary Eddies in Shaping Midlatitude Storm Tracks  

Science Conference Proceedings (OSTI)

Transient and stationary eddies shape the extratropical climate through their transport of heat, moisture, and momentum. In the zonal mean, the transports by transient eddies dominate over those by stationary eddies, but this is not necessarily ...

Yohai Kaspi; Tapio Schneider

2013-08-01T23:59:59.000Z

288

Dual-channel Haptic Synthesis of Viscoelastic Tissue Properties using Programmable Eddy Current Brakes  

Science Conference Proceedings (OSTI)

We describe a novel method for haptic synthesis of viscoelastic responses which employs a dual-channel haptic interface. It has motors that generate torque independently of velocity and brakes that generate viscous torque independently of position. ... Keywords: eddy current brakes, haptic simulation, viscoelastic simulation

Andrew H. C. Gosline; Vincent Hayward

2009-10-01T23:59:59.000Z

289

Radiative Impacts on the Growth of Drops within Simulated Marine Stratocumulus. Part II: Solar Zenith Angle Variations  

Science Conference Proceedings (OSTI)

The effects of solar heating at a variety of solar zenith angles (?o) on the vapor depositional growth of cloud drops, and hence the potential for collection enhancement, is investigated. A large eddy simulation (LES) model is used to predict the ...

Christopher M. Hartman; Jerry Y. Harrington

2005-07-01T23:59:59.000Z

290

Time-dependent simulations of large-scale quantum mechanical processes  

SciTech Connect

Time dependent linear and nonlinear equations govern the evolution of an extensive set of physical systems and processes describing, to enumerate just a few, Bose-Einstein condensates; soliton propagation in optical and photonic band-gap fibers; quantum control of atomic and molecular collisions and reactions; highly-compressed liquids; and dense and ultracold plasmas. While the media vary substantially, the basic computational procedures have many common features. We focus on the nonlinear Schrodinger equation and discuss two powerful approaches to its propagation: the Arnoldi/Lanczos(AL)l and Real Space Product Formula(RSPF)2. Both provide efficient systematic approximations to the short-time exponential propagator that moves the solution between time steps. We implement the former in a discrete variable representation (DVR)3 both in spatial grid and finite element forms and the latter in a spatial mesh with a finite difference representation of the kinetic energy operator. Both approaches require O(N) operations to propagate the wavefunction between time steps and handle multidimensional systems. We shall also draw connections with Liouville formulations used in quantum molecular dynamics simulations of large collections of atoms and molecules. After briefly outlining these formulations, we shall discuss some of the varied applications.

Collins, L. A. (Lee A.)

2002-01-01T23:59:59.000Z

291

Informing public deliberation: value sensitive design of indicators for a large-scale urban simulation  

Science Conference Proceedings (OSTI)

We investigate informing public deliberation regarding major land use and transportation decisions with the results from a sophisticated computer simulation of urban development. Our specific focus is on indicators that portray key results from the simulations. ...

Alan Borning; Batya Friedman; Janet Davis; Peyina Lin

2005-09-01T23:59:59.000Z

292

The Fusion of Isolated Nonlinear Eddies  

Science Conference Proceedings (OSTI)

The interaction of two isolated lens-like eddies is examined with the aid of an inviscid nonlinear model. The barotropic layer in which the lenses are embedded is infinitely deep so that there is no interaction between the eddies unless their ...

Doron Nof

1988-06-01T23:59:59.000Z

293

Recent results and future challenges for large scale Particle-In-Cell simulations of plasma-based accelerator concepts  

Science Conference Proceedings (OSTI)

The concept and designs of plasma-based advanced accelerators for high energy physics and photon science are modeled in the SciDAC COMPASS project with a suite of Particle-In-Cell codes and simulation techniques including the full electromagnetic model, the envelope model, the boosted frame approach and the quasi-static model. In this paper, we report the progress of the development of these models and techniques and present recent results achieved with large-scale parallel PIC simulations. The simulation needs for modeling the plasma-based advanced accelerator at the energy frontier is discussed and a path towards this goal is outlined.

Huang, C.; An, W.; Decyk, V.K.; Lu, W.; Mori, W.B.; Tsung, F.S.; Tzoufras, M.; Morshed, S.; Antomsen, T.; Feng, B.; Katsouleas, T; Fonseca, R.A.; Martins, S.F.; Vieira, J.; Silva, L.O.; Geddes, C.G.R.; Cormier-Michel, E; Vay, J.-L.; Esarey, E.; Leemans, W.P.; Bruhwiler, D.L.; Cowan, B.; Cary, J.R.; Paul, K.

2009-05-01T23:59:59.000Z

294

Microsoft Word - EddyLea20020828.doc  

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

00,000 00,000 to Eddy/Lea Regional Commission Community Reuse Organization WASHINGTON, D.C. - The Department of Energy (DOE) has awarded $400,000 in the form of two competitive grants to the Eddy/Lea Regional Commission. The Eddy/Lea Regional Commission is the community reuse organization (CRO) serving the Department's Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. The Energy Department is a good neighbor to the communities surrounding our sites, Secretary of Energy Spencer Abraham said. "We will continue to work with Eddy/Lea Regional Commission and other community reuse organizations around the country, to retain, expand or create jobs for workers affected by restructuring efforts." The Eddy/Lea Regional Commission applied for funding from the department's Office of Worker

295

Towards large-scale multi-socket, multicore parallel simulations: Performance of an MPI-only semiconductor device simulator  

Science Conference Proceedings (OSTI)

This preliminary study considers the scaling and performance of a finite element (FE) semiconductor device simulator on a set of multi-socket, multicore architectures with nonuniform memory access (NUMA) compute nodes. These multicore architectures include ... Keywords: Drift-diffusion, MPI-only, Multicore, Multicore efficiency, Multilevel preconditioners, Newton-Krylov, Semiconductor devices

Paul T. Lin; John N. Shadid

2010-09-01T23:59:59.000Z

296

Amplification of a Surface-Intensified Eddy Drift along a Steep Shelf in the Eastern Mediterranean Sea  

Science Conference Proceedings (OSTI)

The datasets of the Eddies and Gyre Path Tracking (EGYPT)/EGITTO program in the eastern Mediterranean Sea reveal a large mesoscale anticyclone traveling along the Libyan shelf. Surface drifter trajectories combined with a CTD transect accurately ...

Georgi Sutyrin; Alexander Stegner; Isabelle Taupier-Letage; Samuel Teinturier

2009-07-01T23:59:59.000Z

297

AGE AND MASS FOR 920 LARGE MAGELLANIC CLOUD CLUSTERS DERIVED FROM 100 MILLION MONTE CARLO SIMULATIONS  

SciTech Connect

We present new age and mass estimates for 920 stellar clusters in the Large Magellanic Cloud (LMC) based on previously published broadband photometry and the stellar cluster analysis package, MASSCLEANage. Expressed in the generic fitting formula, d{sup 2} N/dMdt{proportional_to}M{sup {alpha}} t{sup {beta}}, the distribution of observed clusters is described by {alpha} = -1.5 to -1.6 and {beta} = -2.1 to -2.2. For 288 of these clusters, ages have recently been determined based on stellar photometric color-magnitude diagrams, allowing us to gauge the confidence of our ages. The results look very promising, opening up the possibility that this sample of 920 clusters, with reliable and consistent age, mass, and photometric measures, might be used to constrain important characteristics about the stellar cluster population in the LMC. We also investigate a traditional age determination method that uses a {chi}{sup 2} minimization routine to fit observed cluster colors to standard infinite-mass limit simple stellar population models. This reveals serious defects in the derived cluster age distribution using this method. The traditional {chi}{sup 2} minimization method, due to the variation of U, B, V, R colors, will always produce an overdensity of younger and older clusters, with an underdensity of clusters in the log (age/yr) = [7.0, 7.5] range. Finally, we present a unique simulation aimed at illustrating and constraining the fading limit in observed cluster distributions that includes the complex effects of stochastic variations in the observed properties of stellar clusters.

Popescu, Bogdan; Hanson, M. M. [Department of Physics, University of Cincinnati, P.O. Box 210011, Cincinnati, OH 45221-0011 (United States); Elmegreen, Bruce G., E-mail: popescb@mail.uc.edu, E-mail: margaret.hanson@uc.edu, E-mail: bge@us.ibm.com [IBM Research Division, T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)

2012-06-01T23:59:59.000Z

298

A model for simulating impacts of seismic events on large power systems  

Science Conference Proceedings (OSTI)

This paper describes the capabilities and calculation logic of EPfast, a new simulation and impact analysis tool developed by Argonne National Laboratory. The tool represents an emerging set of simulation models focusing on evaluating the vulnerability ... Keywords: multi-component disruptions, power network seismic performance, seismic system vulnerability, system collapse, uncontrolled islanding

Edgar C. Portante; Brian A. Craig; Leah E. Talaber Malone; James A. Kavicky; Stephen F. Folga; Stewart Cedres

2011-04-01T23:59:59.000Z

299

Using Cloud-Resolving Model Simulations of Deep Convection to Inform Cloud Parmaterizations in Large-Scale Models  

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

Using Cloud-Resolving Model Simulations Using Cloud-Resolving Model Simulations of Deep Convection to Inform Cloud Parameterizations in Large-Scale Models S. A. Klein National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory Princeton, New Jersey R. Pincus National Oceanic and Atmospheric Administration Cooperative Institute for Research in Environmental Science Climate Diagnostics Center Boulder, Colorado K. -M. Xu National Aeronautics and Space Administration Langley Research Center Hampton, Virginia Abstract Cloud parameterizations in large-scale models struggle to address the significant non-linear effects of radiation and precipitation that arise from horizontal inhomogeneity in cloud properties at scales smaller than the grid box size of the large-scale models. Statistical cloud schemes provide an attractive

300

Eddy current technique for predicting burst pressure  

DOE Patents (OSTI)

A signal processing technique which correlates eddy current inspection data from a tube having a critical tubing defect with a range of predicted burst pressures for the tube is provided. The method can directly correlate the raw eddy current inspection data representing the critical tubing defect with the range of burst pressures using a regression technique, preferably an artificial neural network. Alternatively, the technique deconvolves the raw eddy current inspection data into a set of undistorted signals, each of which represents a separate defect of the tube. The undistorted defect signal which represents the critical tubing defect is related to a range of burst pressures utilizing a regression technique.

Petri, Mark C. (Yorkville, IL); Kupperman, David S. (Oak Park, IL); Morman, James A. (Woodridge, IL); Reifman, Jaques (Western Springs, IL); Wei, Thomas Y. C. (Downers Grove, IL)

2003-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Forward and adjoint simulations of seismic wave propagation on emerging large-scale GPU architectures  

Science Conference Proceedings (OSTI)

Computational seismology is an area of wide sociological and economic impact, ranging from earthquake risk assessment to subsurface imaging and oil and gas exploration. At the core of these simulations is the modeling of wave propagation in a complex ...

Max Rietmann; Peter Messmer; Tarje Nissen-Meyer; Daniel Peter; Piero Basini; Dimitri Komatitsch; Olaf Schenk; Jeroen Tromp; Lapo Boschi; Domenico Giardini

2012-11-01T23:59:59.000Z

302

Epfast: a model for simulating uncontrolled islanding in large power systems  

Science Conference Proceedings (OSTI)

This paper describes the capabilities, calculation logic, and foundational assumptions of EPfast, a new simulation and impact analysis tool developed by Argonne National Laboratory. The purpose of the model is to explore the tendency of power ...

Edgar C. Portante; Brian A. Craig; Leah Talaber Malone; James Kavicky; Stephen F. Folga; Stewart Cedres

2011-12-01T23:59:59.000Z

303

Regional Climate Simulations over North America: Interaction of Local Processes with Improved Large-Scale Flow  

Science Conference Proceedings (OSTI)

The reasons for biases in regional climate simulations were investigated in an attempt to discern whether they arise from deficiencies in the model parameterizations or are due to dynamical problems. Using the Regional Atmospheric Modeling System ...

Gonzalo Miguez-Macho; Georgiy L. Stenchikov; Alan Robock

2005-04-01T23:59:59.000Z

304

Large-Scale Testing and High-Fidelity Simulation Capabilities at Sandia National Laboratories to Support Space Power and Propulsion  

SciTech Connect

Sandia National Laboratories, as a Department of Energy, National Nuclear Security Agency, has major responsibility to ensure the safety and security needs of nuclear weapons. As such, with an experienced research staff, Sandia maintains a spectrum of modeling and simulation capabilities integrated with experimental and large-scale test capabilities. This expertise and these capabilities offer considerable resources for addressing issues of interest to the space power and propulsion communities. This paper presents Sandia's capability to perform thermal qualification (analysis, test, modeling and simulation) using a representative weapon system as an example demonstrating the potential to support NASA's Lunar Reactor System.

Dobranich, Dean [Thermal and Reactive Processes Department, Sandia National Laboratories Albuquerque, NM 87185 (United States); Blanchat, Thomas K. [Fire Science and Technology Department, Sandia National Laboratories Albuquerque, NM 87185 (United States)

2008-01-21T23:59:59.000Z

305

Anticyclonic Eddies in the Alaskan Stream  

Science Conference Proceedings (OSTI)

Anticyclonic eddies propagating southwestward in the Alaskan Stream (AS) were investigated through analysis of altimetry data from satellite observations during 19922006 and hydrographic data from profiling float observations during 200106. ...

Hiromichi Ueno; Kanako Sato; Howard J. Freeland; William R. Crawford; Hiroji Onishi; Eitarou Oka; Toshio Suga

2009-04-01T23:59:59.000Z

306

Microsoft Word - Big Eddy ROD.doc  

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

Administration's Administration's Big Eddy-Knight Transmission Project Record of Decision September 2011 Decision The Bonneville Power Administration (BPA) has decided to construct the Big Eddy-Knight Transmission Project in Wasco County, Oregon and Klickitat County, Washington. As described in the Big Eddy-Knight Transmission Project Final Environmental Impact Statement (EIS) (DOE/EIS-0421, July 2011), this project consists primarily of constructing a new, approximately 28-mile-long, 500-kilovolt (kV) transmission line and ancillary facilities between BPA's existing Big Eddy Substation in The Dalles, Oregon, to a proposed new Knight Substation that will be connected to an existing BPA line about 4 miles northwest of Goldendale, Washington. For the

307

Eddy Formation in 2-Layer, Quasigeostrophic Jets  

Science Conference Proceedings (OSTI)

The formation of nonlinear eddies in unstable 2-layer, quasigeostrophic jets is investigated using a piecewise constant potential vorticity, contour dynamical model. Both infinite and semi-infinite jet dynamics are explored, considering a ...

Ilson C. A. da Silveira; Glenn R. Flierl

2002-03-01T23:59:59.000Z

308

Western Arctic Shelfbreak Eddies: Formation and Transport  

Science Conference Proceedings (OSTI)

The mean structure and time-dependent behavior of the shelfbreak jet along the southern Beaufort Sea, and its ability to transport properties into the basin interior via eddies are explored using high-resolution mooring data and an idealized ...

Michael A. Spall; Robert S. Pickart; Paula S. Fratantoni; Albert J. Plueddemann

2008-08-01T23:59:59.000Z

309

Temporal Changes in Ocean Eddy Transports  

Science Conference Proceedings (OSTI)

New estimates from 11 yr of altimetric data are made of the global time-average variability kinetic energy and its decadal-scale variability. Making the approximation that the variability reflects primarily eddy motions, a time-mean, but ...

Detlef Stammer; Carl Wunsch; Kyozo Ueyoshi

2006-03-01T23:59:59.000Z

310

Turbulence Spectra and Eddy Diffusivity over Forests  

Science Conference Proceedings (OSTI)

The main objectives of this observational study are to examine the stability dependence of velocity and air temperature spectra and to employ the spectral quantities to establish relations for eddy diffusivity over forests. The datasets chosen ...

Xuhui Lee

1996-08-01T23:59:59.000Z

311

ORISE Faculty Research Experiences: Dr. Eddie Red  

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

nanotube characteristics-technology that could impact future solar cells, as well as battery and fuel cells. Eddie C. Red, Ph.D., has longed to set up a functional research...

312

Direct Atmospheric Forcing of Geostrophic Eddies  

Science Conference Proceedings (OSTI)

To assess the role of direct stochastic wind forcing in generating oceanic geostrophic eddies we calculate analytically the response of a simple ocean model to a realistic model wind-stress spectrum and compare the results with observations. The ...

Peter Mller; Claude Frankignoul

1981-03-01T23:59:59.000Z

313

Identification of Marine Eddies from Altimetric Maps  

Science Conference Proceedings (OSTI)

A procedure is presented to detect eddy cores from sea level anomaly (SLA) maps obtained from altimetric measurements. The method is based on finding the sign of Q, which is an invariant of the velocity gradient tensor (u). This parameter, ...

Jordi Isern-Fontanet; Emilio Garca-Ladona; Jordi Font

2003-05-01T23:59:59.000Z

314

Thermohaline Structure of an Eddy-Resolving North Atlantic Model: The Influence of Boundary Conditions  

Science Conference Proceedings (OSTI)

A TS volumetric census, with a resolution of 0.2C and 0.1 psu, for years 20-25 of the World Ocean Circulation Experiment Community Modeling Effort eddy-resolving simulation of the equatorial and North Atlantic Ocean, reveals how the ...

John M. Klinck

1995-06-01T23:59:59.000Z

315

Decadal Variability of the Kuroshio Extension: Observations and an Eddy-Resolving Model Hindcast  

Science Conference Proceedings (OSTI)

Low-frequency variability of the Kuroshio Extension (KE) is studied using observations and a multidecadal (19502003) hindcast by a high-resolution (0.1), eddy-resolving, global ocean general circulation model for the Earth Simulator (OFES). In ...

Bunmei Taguchi; Shang-Ping Xie; Niklas Schneider; Masami Nonaka; Hideharu Sasaki; Yoshikazu Sasai

2007-06-01T23:59:59.000Z

316

Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses  

E-Print Network (OSTI)

Following an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied.

Chen, Qiang

2005-05-01T23:59:59.000Z

317

Eddy formation and propagation in the eastern tropical Pacific  

E-Print Network (OSTI)

Observations of eddies in the eastern tropical Pacific from TOPEX altimetry data show that there are seasonal and interannual variations in eddy activity. Comparisons between time of eddy formation and corresponding wind data show that not all eddies are caused by winds blowing offshore from the coast of Central America. Plots of eddy tracks from TOPEX data show that some of these eddies last for over 6 months and travel more than 250 of longitude toward the west. Others go more towards the equator and dissipate quickly. A General Circulation Model is used to study the formation and propagation aspects of these eddies. Results from experiments exploring the formation mechanism show that high frequency wind bursts are sufficient but not necessary for eddy formation in the eastern tropical Pacific. Eddy activity remains almost the same if only the annual harmonic of the wind field is used to force the model. Forcing the model with only the high frequency wind component produces almost no eddies. The formation of eddies during periods of weak offshore winds suggests other possible mechanisms, such as unstable mean flows, for the formation of the eddies. Experiments done to study the propagation of the eddies show that the eddies are greatly affected by the structure of the background flow. Eddies formed in September or October encounter a strong westward flowing current and do not dissipate rapidly. These eddies do not travel south beyond the region of shear between the currents. They last for more than 6 months and travel westward for more than 250 of longitude. Eddies formed in March and April encounter a strong eastward flow dissipate quickly and propagate towards the equator where they disappear. These eddies last for less than four months and cover less than 150 of longitude. Eddies generated in January show properties between these two extreme cases.

Jhingran, Vikas Gopal

1997-01-01T23:59:59.000Z

318

Numerical simulations of turbulent flow fields caused by spraying of water on large releases of hydrogen fluoride  

Science Conference Proceedings (OSTI)

The effectiveness of water sprays in absorbing HF releases was recently demonstrated in extended laboratory and field tests. In this paper, computer simulations are presented of the Hawk, Nevada Test Site, series of field tests. The model used, HFSPRAY, is a Eulerean/Lagrangian model which simulates the momentum, mass and energy interactions between a water spray and a turbulent plume of HF in air; the model can predict the flow velocities, temperature, water vapor, and HF concentration fields in two-dimensional large- geometries for spraying in any direction, (i.e., down-flow, inclined-down-flow, up-flow, and co-current horizontal flow). The model was validated against recent data on spraying of water on large releases of HF. 17 refs., 11 figs., 4 tabs.

Fthenakis, V.M. (Brookhaven National Lab., Upton, NY (United States)); Schatz, K.W. (Mobil Research and Development Corp., Princeton, NJ (United States))

1991-05-01T23:59:59.000Z

319

Large-scale molecular dynamics simulations of shock-induced plasticity, phase transformations, and detonation  

SciTech Connect

Modern computers enable routine multimillion-atom molecular dynamics simulations of shock propagation in solids using realistic interatomic potentials, and offer a direct insight into the atomistic processes underlying plasticity, phase transformations, and the detonation of energetic materials. Past, present, and prospects for future simulations will be discussed in the context of prototypical systems for each of these three classes of problems. Initial samples ranging from perfect single crystals, to those with specific isolated defects, to full-fledged polycrystalline materials will be considered.

Germann, T. C. (Timothy C.)

2001-06-01T23:59:59.000Z

320

A FINITE ELEMENT APPROACH FOR SIMULATING THE QUENCHING OF LARGE ALUMINIUM COMPRESSOR WHEELS  

E-Print Network (OSTI)

to relaxing or affect the stress distribution during operation of the wheel. 1 University of Applied Sciences fluxes) and then the mechanical simulation (stress-strain) using the transient temperature distribution and steam bubbles, as shown in Figure 2. At the beginning of the quenching, the entire wheel is surrounded

Note: This page contains sample records for the topic "large eddy simulation" 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

A particle-based method for large-scale breaking waves simulation  

Science Conference Proceedings (OSTI)

We address in this paper the problem of particle-based simulation of breaking waves. We present a new set of equations based on oceanographic research which allow us to deal with several types of breaking waves and multiple wave trains with full control ...

Emmanuelle Darles; Benoit Crespin; Djamchid Ghazanfarpour

2010-09-01T23:59:59.000Z

322

Modeling ramp compression experiments using large-scale molecular dynamics simulation.  

Science Conference Proceedings (OSTI)

Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.

Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)

2011-10-01T23:59:59.000Z

323

Comparing Large-Scale Hydrological Model Simulations to Observed Runoff Percentiles in Europe  

Science Conference Proceedings (OSTI)

Large-scale hydrological models describing the terrestrial water balance at continental and global scales are increasingly being used in earth system modeling and climate impact assessments. However, because of incomplete process understanding and ...

Lukas Gudmundsson; Lena M. Tallaksen; Kerstin Stahl; Douglas B. Clark; Egon Dumont; Stefan Hagemann; Nathalie Bertrand; Dieter Gerten; Jens Heinke; Naota Hanasaki; Frank Voss; Sujan Koirala

2012-04-01T23:59:59.000Z

324

Sensitivity Study of Regional Climate Model Simulations to Large-Scale Nudging Parameters  

Science Conference Proceedings (OSTI)

Previous studies with nested regional climate models (RCMs) have shown that large-scale spectral nudging (SN) seems to be a powerful method to correct RCMs weaknesses such as internal variability, intermittent divergence in phase space (IDPS), ...

Adelina Alexandru; Ramon de Elia; Ren Laprise; Leo Separovic; Sbastien Biner

2009-05-01T23:59:59.000Z

325

User's manual for computer code SOLTES-1 (simulator of large thermal energy systems). [For CDC 6600  

DOE Green Energy (OSTI)

SOLTES simulates the steady-state response of thermal energy systems to time-varying data such as weather and loads. Thermal energy system models of both simple and complex systems can easily be modularly constructed from a library of routines. These routines mathematically model solar collectors, pumps, switches, thermal energy storage, thermal boilers, auxiliary boilers, heat exchangers, extraction turbines, extraction turbine/generators, condensers, regenerative heaters, air conditioners, heating and cooling of buildings, process vapor, etc.; SOLTES also allows user-supplied routines. The analyst need only specify fluid names to obtain readout of property data for heat-transfer fluids and constants that characterize power-cycle working fluids from a fluid property data bank. A load management capability allows SOLTES to simulate total energy systems that simultaneously follow heat and power loads and demands. Generalized energy accounting is available, and values for system performance parameters may be automatically determined by SOLTES. Because of its modularity and flexibility, SOLTES can be used to simulate a wide variety of thermal energy systems such as solar power/total energy, fossil fuel power plants/total energy, nuclear power plants/total energy, solar energy heating and cooling, geothermal energy, and solar hot water heaters.

Fewell, M.E.; Grandjean, N.R.; Dunn, J.C.; Edenburn, M.W.

1978-09-01T23:59:59.000Z

326

Diagnostic Study of the Effects of a Large City on Heavy Rainfall as Revealed by an Ensemble Simulation: A Case Study of Central Tokyo, Japan  

Science Conference Proceedings (OSTI)

This study was undertaken to investigate the effects of a large city on heavy rainfall in Tokyo, Japan, based on an ensemble simulation with a large number of members. An ensemble simulation (24 members) of eight brief heavy rainfall events that ...

Tomohiko Inamura; Takeki Izumi; Hiroshi Matsuyama

2011-03-01T23:59:59.000Z

327

Three-dimensional simulations of geometrically complex subduction with large viscosity variations  

Science Conference Proceedings (OSTI)

The incorporation of geologic realism into numerical models of subduction is becoming increasingly necessary as observational and experimental constraints indicate plate boundaries are inherently three-dimensional (3D) in nature and contain large viscosity ... Keywords: ACM proceedings, mantle convection, multigrid, rheology, subduction

Margarete A. Jadamec; Magali I. Billen; Oliver Kreylos

2012-07-01T23:59:59.000Z

328

Smoke-Plume Distributions above Large-Scale Fires: Implications for Simulations of Nuclear Winter  

Science Conference Proceedings (OSTI)

Smoke from raging fires produced in the aftermath of a major nuclear exchange has been predicted to cause large decreases in surface temperatures. However, the extent of the decrease and even the sign of the temperature change depend on how the ...

J. E. Penner; L. C. Haselman Jr.; L. L. Edwards

1986-10-01T23:59:59.000Z

329

The Impact of Initial Condition Uncertainty on Numerical Simulations of Large-scale Explosive Cyclogenesis  

Science Conference Proceedings (OSTI)

The impact of initial condition uncertainty on short-range (up to 48 h) forecasts of large-scale explosive cyclogenesis is examined. Predictability experiments are conducted on 11 cases of rapid oceanic cyclogenesis that occurred in a long-term, ...

Steven L. Mullen; David P. Baumhefner

1989-12-01T23:59:59.000Z

330

Computed and experimental interactions between eddy structure and dispersed particles in developing free shear layers  

SciTech Connect

We are investigating the interactive process between turbulent flow and dispersed phase particles. We are focusing on the mechanisms that appear to result in a reduction of local turbulent intensity and a corresponding reduction in wall heat transfer and subsequent wall erosion in turbulent solid propellant combustion flow. We apply computational simulations and physical experiments specialized to a developing free shear layer over a rearward facing step and over a parallel splitter plate. The flow configuration evolves in a two-dimensional, steady, combustion and non-combustion turbulent free shear mixing region, with and without particle additives. The computational simulations combine three basic components: gas phase Navier-Stokes solutions, Lagrange particle field solutions and a Monte Carlo technique for the random encounters, forces and accelerations between the two fields. We concentrate here on relatively large sized additive particles (of the order of tens of microns to 100 microns mean diameter). We examine their apparent influence in breaking up the larger, energy bearing eddy structures into smaller structures which are more readily dissipated.

Buckingham, A.C.; Siekhaus, W.J.; Keller, J.O.; Ellzey, J.; Hubbard, G.; Daily, J.W.

1982-05-20T23:59:59.000Z

331

ActivitySim: large-scale agent based activity generation for infrastructure simulation  

SciTech Connect

The United States' Department of Homeland Security aims to model, simulate, and analyze critical infrastructure and their interdependencies across multiple sectors such as electric power, telecommunications, water distribution, transportation, etc. We introduce ActivitySim, an activity simulator for a population of millions of individual agents each characterized by a set of demographic attributes that is based on US census data. ActivitySim generates daily schedules for each agent that consists of a sequence of activities, such as sleeping, shopping, working etc., each being scheduled at a geographic location, such as businesses or private residences that is appropriate for the activity type and for the personal situation of the agent. ActivitySim has been developed as part of a larger effort to understand the interdependencies among national infrastructure networks and their demand profiles that emerge from the different activities of individuals in baseline scenarios as well as emergency scenarios, such as hurricane evacuations. We present the scalable software engineering principles underlying ActivitySim, the socia-technical modeling paradigms that drive the activity generation, and proof-of-principle results for a scenario in the Twin Cities, MN area of 2.6 M agents.

Gali, Emmanuel [Los Alamos National Laboratory; Eidenbenz, Stephan [Los Alamos National Laboratory; Mniszewski, Sue [Los Alamos National Laboratory; Cuellar, Leticia [Los Alamos National Laboratory; Teuscher, Christof [PORTLAND STATE UNIV

2008-01-01T23:59:59.000Z

332

Sensitivity of Simulated Climate to Model Resolution  

Science Conference Proceedings (OSTI)

Dynamical measures of the climate (e.g., winds, eddy fluxes) simulated by a general circulation model are compared at different horizontal and vertical resolutions for the December, January, and February period. The simulations of the troposphere ...

Byron A. Boville

1991-05-01T23:59:59.000Z

333

A Linear Theory of Extratropical Synoptic Eddy Statistics  

Science Conference Proceedings (OSTI)

This paper investigates the extent to which the statistics of extratropical synoptic eddies may be deduced from the assumption that the eddies are stochastically forced disturbances evolving on a baroclinically stable background flow. To this end,...

Jeffrey S. Whitaker; Prashant D. Sardeshmukh

1998-01-01T23:59:59.000Z

334

The effects of ocean eddies on tropical cyclones  

E-Print Network (OSTI)

The purpose of this study is to understand the interactions of tropical cyclones with ocean eddies. In particular we examine the influence of a cold-core eddy on the cold wake formed during the passage of Typhoon Fanapi ...

Miltenberger, Alexander Reid

2012-01-01T23:59:59.000Z

335

Scaling Baroclinic Eddy Fluxes: Vortices and Energy Balance  

Science Conference Proceedings (OSTI)

The eddy heat flux generated by the statistically equilibrated baroclinic instability of a uniform, horizontal temperature gradient is studied using a two-mode f-plane quasigeostrophic model. An overview of the dependence of the eddy diffusivity ...

Andrew F. Thompson; William R. Young

2006-04-01T23:59:59.000Z

336

Float Observations of the Southern Ocean. Part II: Eddy Fluxes  

Science Conference Proceedings (OSTI)

Autonomous Lagrangian Circulation Explorer (ALACE) floats are used to examine eddy fluxes in the Southern Ocean. Eddy fluxes are calculated from differences between ALACE float data and mean fields derived from hydrographic atlas data or ...

Sarah T. Gille

2003-06-01T23:59:59.000Z

337

Laboratory Experiments on the Merging of Nonlinear Anticyclonic Eddies  

Science Conference Proceedings (OSTI)

The mutual interaction of two isolated lenslike eddies is examined with the aid of a laboratory experiment on a rotating table. The isolated anticyclonic eddies are formed by withdrawing two cylinders containing a mixture of Freon (with a density ...

Doron Nof; Leslie M. Simon

1987-03-01T23:59:59.000Z

338

Validation of Parameterization Scheme for Eddy Diffusion from Satellite Data  

Science Conference Proceedings (OSTI)

The eddy diffusion coefficient Kyy has been calculated using LIMS data for the months of December 1978 and January and February 1979. Two methods have been used. The first implements the suggestion made by Tung (1987) to parameterize the eddy ...

F. Sassi; G. Visconti; J. C. Gille

1990-11-01T23:59:59.000Z

339

Bottom Ekman Pumping with Stress-Dependent Eddy Viscosity  

Science Conference Proceedings (OSTI)

This paper reconsiders the classic problem of bottom Ekman pumping below a steady geostrophic flow by relaxing the assumption of a constant eddy viscosity. It is assumed instead that the eddy viscosity depends on the magnitude of the bottom ...

Benoit Cushman-Roisin; Vlado Mala?i?

1997-09-01T23:59:59.000Z

340

On the ?-Induced Movement of Isolated Baroclinic Eddies  

Science Conference Proceedings (OSTI)

In this paper an analytical method is proposed for calculating the nonlinear ?-induced translation of isolated baroclinic eddies. The study focuses on frictionless anticyclonic eddies with a uniform anomalous density and a lens-like cross section ...

Doron Nof

1981-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Eddy Correlation Flux Measurement System (ECOR) Handbook  

SciTech Connect

The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.

Cook, DR

2011-01-31T23:59:59.000Z

342

Demand Shifting With Thermal Mass in Large Commercial Buildings:Field Tests, Simulation and Audits  

SciTech Connect

The principle of pre-cooling and demand limiting is to pre-cool buildings at night or in the morning during off-peak hours, storing cooling in the building thermal mass and thereby reducing cooling loads and reducing or shedding related electrical demand during the peak periods. Cost savings are achieved by reducing on-peak energy and demand charges. The potential for utilizing building thermal mass for load shifting and peak demand reduction has been demonstrated in a number of simulation, laboratory, and field studies (Braun 1990, Ruud et al. 1990, Conniff 1991, Andresen and Brandemuehl 1992, Mahajan et al. 1993, Morris et al. 1994, Keeney and Braun 1997, Becker and Paciuk 2002, Xu et al. 2003). This technology appears to have significant potential for demand reduction if applied within an overall demand response program. The primary goal associated with this research is to develop information and tools necessary to assess the viability of and, where appropriate, implement demand response programs involving building thermal mass in buildings throughout California. The project involves evaluating the technology readiness, overall demand reduction potential, and customer acceptance for different classes of buildings. This information can be used along with estimates of the impact of the strategies on energy use to design appropriate incentives for customers.

Xu, Peng; Haves, Philip; Piette, Mary Ann; Zagreus, Leah

2005-09-01T23:59:59.000Z

343

Anisotropic Material Transport by Eddies and Eddy-Driven Currents in a Model of the North Atlantic  

Science Conference Proceedings (OSTI)

This study analyzes anisotropic properties of the material transport by eddies and eddy-driven zonal jets in a general circulation model of the North Atlantic through the analysis of Lagrangian particle trajectories. Spreading ratesdefined here ...

Igor Kamenkovich; Pavel Berloff; Joseph Pedlosky

2009-12-01T23:59:59.000Z

344

Joint Vortices, Eastward Propagating Eddies and Migratory Taylor Columns  

Science Conference Proceedings (OSTI)

The behavior of an isolated pair of vortices consisting of two eddies situated on top of each other in a three-layer ocean is examined analytically. The amplitudes of both eddies are high and, consequently, the two eddies behave as one unit and ...

Doron Nof

1985-08-01T23:59:59.000Z

345

An expert system for analyzing eddy current measurements  

DOE Patents (OSTI)

A method and apparatus (called DODGER) analyzes eddy current data for heat exchanger tubes or any other metallic object. DODGER uses an expert system to analyze eddy current data by reasoning with uncertainty and pattern recognition. The expert system permits, DODGER to analyze eddy current data intelligently, an obviate operator uncertainty by analyzing the data in a uniform and consistent manner.

Levy, A.J.; Oppenlander, J.E.; Brudnoy, D.M.; Englund, J.M.; Loomis, K.C.

1991-12-31T23:59:59.000Z

346

Analysis of a California Catalina Eddy Event  

Science Conference Proceedings (OSTI)

During the period 2629 May 1968 a shallow cyclonic circulation, known 1ocally as a Catalina eddy, developed in the offshore waters of southern California. A synoptic and mesoscale analysis of the event establishes the following: 1) the incipient ...

Lance F. Bosart

1983-08-01T23:59:59.000Z

347

ENSO Effects on Gulf of Alaska Eddies  

Science Conference Proceedings (OSTI)

Generation and propagation of eddies in the coastal regions of the eastern Gulf of Alaska are examined based on ouput from a numerical ocean model. Results from a 1/8 six-layer isopycnal, wind-forced Pacific basin model are examined within the ...

Arne Melsom; Steven D. Meyers; James J. O'Brien; Harley E. Hurlburt; Joseph E. Metzger

1999-01-01T23:59:59.000Z

348

Japan/East Sea Intrathermocline Eddies  

Science Conference Proceedings (OSTI)

Intrathermocline eddies (ITE) with diameters of 100 km and of thickness greater than 100 m are observed within each of the three quasi-stationary meanders of the Tsushima Current of the Japan/East Sea. Within the ITE homogenous, anticyclonic ...

Arnold L. Gordon; Claudia F. Giulivi; Craig M. Lee; Heather Hunt Furey; Amy Bower; Lynne Talley

2002-06-01T23:59:59.000Z

349

PRATHAM: Parallel Thermal Hydraulics Simulations using Advanced Mesoscopic Methods  

SciTech Connect

At the Oak Ridge National Laboratory, efforts are under way to develop a 3D, parallel LBM code called PRATHAM (PaRAllel Thermal Hydraulic simulations using Advanced Mesoscopic Methods) to demonstrate the accuracy and scalability of LBM for turbulent flow simulations in nuclear applications. The code has been developed using FORTRAN-90, and parallelized using the message passing interface MPI library. Silo library is used to compact and write the data files, and VisIt visualization software is used to post-process the simulation data in parallel. Both the single relaxation time (SRT) and multi relaxation time (MRT) LBM schemes have been implemented in PRATHAM. To capture turbulence without prohibitively increasing the grid resolution requirements, an LES approach [5] is adopted allowing large scale eddies to be numerically resolved while modeling the smaller (subgrid) eddies. In this work, a Smagorinsky model has been used, which modifies the fluid viscosity by an additional eddy viscosity depending on the magnitude of the rate-of-strain tensor. In LBM, this is achieved by locally varying the relaxation time of the fluid.

Joshi, Abhijit S [ORNL; Jain, Prashant K [ORNL; Mudrich, Jaime A [ORNL; Popov, Emilian L [ORNL

2012-01-01T23:59:59.000Z

350

HIGH-TEMPERATURE ELECTROLYSIS FOR LARGE-SCALE HYDROGEN AND SYNGAS PRODUCTION FROM NUCLEAR ENERGY SYSTEM SIMULATION AND ECONOMICS  

DOE Green Energy (OSTI)

A research and development program is under way at the Idaho National Laboratory (INL) to assess the technological and scale-up issues associated with the implementation of solid-oxide electrolysis cell technology for efficient high-temperature hydrogen production from steam. This work is supported by the US Department of Energy, Office of Nuclear Energy, under the Nuclear Hydrogen Initiative. This paper will provide an overview of large-scale system modeling results and economic analyses that have been completed to date. System analysis results have been obtained using the commercial code UniSim, augmented with a custom high-temperature electrolyzer module. Economic analysis results were based on the DOE H2A analysis methodology. The process flow diagrams for the system simulations include an advanced nuclear reactor as a source of high-temperature process heat, a power cycle and a coupled steam electrolysis loop. Several reactor types and power cycles have been considered, over a range of reactor outlet temperatures. Pure steam electrolysis for hydrogen production as well as coelectrolysis for syngas production from steam/carbon dioxide mixtures have both been considered. In addition, the feasibility of coupling the high-temperature electrolysis process to biomass and coal-based synthetic fuels production has been considered. These simulations demonstrate that the addition of supplementary nuclear hydrogen to synthetic fuels production from any carbon source minimizes emissions of carbon dioxide during the production process.

J. E. O'Brien; M. G. McKellar; E. A. Harvego; C. M. Stoots

2009-05-01T23:59:59.000Z

351

On physical interpretation of two dimensional time-correlations regarding time delay velocities and eddy shaping  

SciTech Connect

Time delay estimation (TDE) techniques are frequently used to estimate the flow velocity from fluctuating measurements. Tilted structures carried by the flow lead to misinterpretation of the time delays in terms of velocity direction and amplitude. It affects TDE measurements from probes, and is also intrinsically important for beam emission spectroscopy and gas puff imaging measurements. Local eddy shapes estimated from 2D fluctuating field are necessary to gain a more accurate flow estimate from TDE, as illustrated by Langmuir probe array measurements. A least square regression approach is proposed to estimate both flow field and shaping parameters. The technique is applied to a test case built from numerical simulation of interchange fluctuations. The local eddy shape does not only provide corrections for the velocity field but also quantitative information about the statistical interaction mechanisms between local eddies and E Multiplication-Sign B flow shear. The technique is then tested on gaz puff imaging data collected at the edge of EAST tokamak plasmas. It is shown that poloidal asymmetries of the fluctuation fields-velocity and eddy shape-are consistent at least qualitatively with a ballooning type of turbulence immersed in a radially sheared equilibrium flow.

Fedorczak, N. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Manz, P. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); Max-Planck-Institut feur Plasmaphysik, Association Euratom-IPP, 85748Garching (Germany); Thakur, S. C.; Xu, M.; Tynan, G. R. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego, California 92093 (United States); Xu, G. S.; Liu, S. C. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2012-12-15T23:59:59.000Z

352

Improved Representation of Upper-Ocean Dynamics and Mixed Layer Depths in a Model of the North Atlantic on Switching from Eddy-Permitting to Eddy-Resolving Grid Resolution  

Science Conference Proceedings (OSTI)

Two configurations of a primitive-equation model of the North Atlantic are analyzed with respect to the simulated cycling of energy, mass, and heat in the upper ocean. One model is eddy-permitting (1/3 horizontal resolution), the other one is ...

Andreas Oschlies

2002-08-01T23:59:59.000Z

353

Eddy current inspection tool. [Patent application  

DOE Patents (OSTI)

A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment with a probe coil, and associated coaxial coil cable, oil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of a fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator for generating audible signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.

Petrini, R.R.; Van Lue, D.F.

1980-10-29T23:59:59.000Z

354

Eddy Current Analysis in the Presence of Ferromagnetic Crud  

Science Conference Proceedings (OSTI)

Tenacious ferromagnetic crud deposits on fuel rods interfere with accurate assessment of cladding corrosion by standard poolside eddy current methods. To address this problem, EPRI developed an advanced method of analyzing eddy current response to simultaneously deduce cladding corrosion, crud thickness, and metal loss. In a previous EPRI study, "Eddy Current Measurements of Hydrogen Concentration and Metal Loss in Zircaloy Samples" (1003132), investigators established the feasibility of this method by p...

2003-12-17T23:59:59.000Z

355

Mesoscale Eddies in the Gulf of Alaska: Observations and Implications  

E-Print Network (OSTI)

southwest, out along the Aleutian Chain, some Alaskan StreamKenai eddy out along the Aleutian Chain, where it was still

Rovegno, Peter

2012-01-01T23:59:59.000Z

356

The effects of ocean eddies on tropical cyclones.  

E-Print Network (OSTI)

??The purpose of this study is to understand the interactions of tropical cyclones with ocean eddies. In particular we examine the influence of a cold-core (more)

Miltenberger, Alexander Reid

2012-01-01T23:59:59.000Z

357

Eddy Viscosity and Stochastic Backscatter Parameterizations on the Sphere for Atmospheric Circulation Models  

Science Conference Proceedings (OSTI)

Stochastic backscatter, eddy drain viscosity, and net eddy viscosity parameterizations are formulated and calculated for two-dimensional turbulence on the sphere based on eddy damped quasi-normal Markovian and direct interaction approximation ...

Jorgen S. Frederiksen; Antony G. Davies

1997-10-01T23:59:59.000Z

358

The Role of LandSea Topography in Blocking Formation in a BlockEddy Interaction Model  

Science Conference Proceedings (OSTI)

This paper is an extension of a theoretical study by Luo on the effect of large-scale landsea contrast (LSC) topography on the formation of an eddy-driven blocking. It is found that the topography term can be included explicitly in the blocking ...

Dehai Luo; Zhe Chen

2006-11-01T23:59:59.000Z

359

Department of Energy Awards $400,000 to Eddy/Lea Regional Commission...  

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

to EddyLea Regional Commission Community Reuse Organization Department of Energy Awards 400,000 to EddyLea Regional Commission Community Reuse Organization Department of...

360

Steam Generator Automated Eddy Current Data Analysis: A Benchmarking Study  

Science Conference Proceedings (OSTI)

This benchmarking study informs utility nondestructive evaluation (NDE) engineers of the status of automating analysis of data from steam generator tube eddy current testing. Study results will contribute to a detailed plan for continuing development of automated data analysis system processes. One day, automated data analysis will provide utilities with a consistent, accurate, and cost-effective method of analyzing eddy current inspection data.

1998-12-16T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Beta-Induced Translation of Strong Isolated Eddies  

Science Conference Proceedings (OSTI)

Strong eddies on the ? plane are considered within the framework of the one-layer primitive equations. The attention is focused on calculating the ?-induced changes to the spatial structure of the eddy, as well as the speed of its translation. In ...

E. S. Benilov

1996-10-01T23:59:59.000Z

362

EddyMean Flow Interaction in the Kuroshio Extension Region  

Science Conference Proceedings (OSTI)

The authors use data collected by a line of tall current meter moorings deployed across the axis of the Kuroshio Extension (KE) jet at the location of maximum time-mean eddy kinetic energy to characterize the mean jet structure, the eddy ...

Stephanie Waterman; Nelson G. Hogg; Steven R. Jayne

2011-06-01T23:59:59.000Z

363

Eddy-Induced Instability for Low-Frequency Variability  

Science Conference Proceedings (OSTI)

Synoptic eddymean flow interaction has been recognized as one of the key sources for extratropical low-frequency variability. In this paper, the underlying dynamics of this interaction are examined from the perspective of a synoptic eddy-induced ...

F-F. Jin

2010-06-01T23:59:59.000Z

364

Finding Tropical Cyclones on a Cloud Computing Cluster: Using Parallel Virtualization for Large-Scale Climate Simulation Analysis  

E-Print Network (OSTI)

Chang. Changes in Tropical Cyclone Number, Duration, andSimulation of Future Tropical Cyclone Statistics in a High-Finding Tropical Cyclones on a Cloud Computing Cluster:

Hasenkamp, Daren

2011-01-01T23:59:59.000Z

365

Correcting eddy-covariance flux underestimates over a grassland.  

Science Conference Proceedings (OSTI)

Independent measurements of the major energy balance flux components are not often consistent with the principle of conservation of energy. This is referred to as a lack of closure of the surface energy balance. Most results in the literature have shown the sum of sensible and latent heat fluxes measured by eddy covariance to be less than the difference between net radiation and soil heat fluxes. This under-measurement of sensible and latent heat fluxes by eddy-covariance instruments has occurred in numerous field experiments and among many different manufacturers of instruments. Four eddy-covariance systems consisting of the same models of instruments were set up side-by-side during the Southern Great Plains 1997 Hydrology Experiment and all systems under-measured fluxes by similar amounts. One of these eddy-covariance systems was collocated with three other types of eddy-covariance systems at different sites; all of these systems under-measured the sensible and latent-heat fluxes. The net radiometers and soil heat flux plates used in conjunction with the eddy-covariance systems were calibrated independently and measurements of net radiation and soil heat flux showed little scatter for various sites. The 10% absolute uncertainty in available energy measurements was considerably smaller than the systematic closure problem in the surface energy budget, which varied from 10 to 30%. When available-energy measurement errors are known and modest, eddy-covariance measurements of sensible and latent heat fluxes should be adjusted for closure. Although the preferred method of energy balance closure is to maintain the Bowen-ratio, the method for obtaining closure appears to be less important than assuring that eddy-covariance measurements are consistent with conservation of energy. Based on numerous measurements over a sorghum canopy, carbon dioxide fluxes, which are measured by eddy covariance, are underestimated by the same factor as eddy covariance evaporation measurements when energy balance closure is not achieved.

Twine, T. E.; Kustas, W. P.; Norman, J. M.; Cook, D. R.; Houser, P. R.; Meyers, T. P.; Prueger, J. H.; Starks, P. J.; Wesely, M. L.; Environmental Research; Univ. of Wisconsin at Madison; DOE; National Aeronautics and Space Administration; National Oceanic and Atmospheric Administrationoratory

2000-06-08T23:59:59.000Z

366

A Numerical Study of the Influence of a Clearcut on Eddy-Covariance Fluxes of CO2 Measured Above a Forest  

Science Conference Proceedings (OSTI)

We compare the contributions of unit source fluxes over a clear-cutting area in a forest and over the contiguous forested area to the eddy-covariance (EC) flux of CO2 measured at a tower standing in the center of the clearcut under daytime convective conditions. The large-eddy simulation (LES) technique is used to simulate the dispersion and transport of two conservative and passive tracers that are released from the clearcut and from the forested area, respectively. The time series of the LES-generated vertical velocity and the mixing ratios of both tracers on all the levels at the tower location are recorded every model time step during the last hour of each LES run; this somewhat mimics real EC flux measurements at the tower. The contribution of the unit surface flux over the clearcut relative to that over the forested area decreases exponentially with increasing measurement height, decreasing convective boundary layer depth, increasing atmospheric stability, and decreasing size of the clearcut. LES-derived results are fitted to an empirical relation and applied to flux measurements at the 447-m tall tower in Wisconsin, USA. The contribution of the unit flux over the clearcut on the EC flux measured at the 30-m level of the tower is larger than 50% of that over the forested area under most unstable conditions, while smaller than 2.5% at the 396-m level. Existing analytical footprint models are inappropriate to address the clearcut influence due to clearcut-induced heterogeneity of the turbulent flow in the tower area.

Wang, Weiguo; Davis, Kenneth J.

2008-09-03T23:59:59.000Z

367

Simulating the seismic performance of a large-scale electric network in the U.S. midwest  

Science Conference Proceedings (OSTI)

This paper summarizes the methodology and simulation tools used by Argonne National Laboratory to examine the impact that a high-intensity New Madrid seismic event could have on local electric assets and the performance of surrounding regional electric ...

Edgar C. Portante; James A. Kavicky; Stephen F. Folga; Brian A. Craig; Leah E. Talaber; Gustav R. Wulfkuhle

2010-12-01T23:59:59.000Z

368

Standard Test Method for Determining Electrical Conductivity Using the Electromagnetic (Eddy-Current) Method  

E-Print Network (OSTI)

Standard Test Method for Determining Electrical Conductivity Using the Electromagnetic (Eddy-Current) Method

American Society for Testing and Materials. Philadelphia

2009-01-01T23:59:59.000Z

369

Standard Practice for Electromagnetic (Eddy-Current) Examination of Copper Redraw Rod for Electrical Purposes  

E-Print Network (OSTI)

Standard Practice for Electromagnetic (Eddy-Current) Examination of Copper Redraw Rod for Electrical Purposes

American Society for Testing and Materials. Philadelphia

2009-01-01T23:59:59.000Z

370

Vertical Eddy Energy Fluxes in the North Atlantic Subtropical and Subpolar Gyres  

Science Conference Proceedings (OSTI)

Eddy energy generation and energy fluxes are examined in a realistic eddy-resolving model of the North Atlantic. Over 80% of the wind energy input is found to be released by the generation of eddies through baroclinic instability. The eddy energy ...

Xiaoming Zhai; David P. Marshall

2013-01-01T23:59:59.000Z

371

On the Use of Integrated Daylighting and Energy Simulations to Drive the Design of a Large Net-Zero Energy Office Building: Preprint  

SciTech Connect

This paper illustrates the challenges of integrating rigorous daylight and electric lighting simulation data with whole-building energy models, and defends the need for such integration to achieve aggressive energy savings. Through a case study example, we examine the ways daylighting -- and daylighting simulation -- drove the design of a large net-zero energy project. We give a detailed review of the daylighting and electric lighting design process for the National Renewable Energy Laboratory's Research Support Facility (RSF), a 220,000 ft2 net-zero energy project the author worked on as a daylighting consultant. A review of the issues involved in simulating and validating the daylighting performance of the RSF will be detailed, including daylighting simulation, electric lighting control response, and integration of Radiance simulation data into the building energy model. Daylighting was a key strategy in reaching the contractual energy use goals for the RSF project; the building's program, layout, orientation and interior/furniture design were all influenced by the daylighting design, and simulation was critical in ensuring these many design components worked together in an integrated fashion, and would perform as required to meet a very aggressive energy performance goal, as expressed in a target energy use intensity.

Guglielmetti, R.; Pless, S.; Torcellini, P.

2010-08-01T23:59:59.000Z

372

Mesoscale Convective Systems in Weakly Forced Large-Scale Environments. Part III: Numerical Simulations and Implications for Operational Forecasting  

Science Conference Proceedings (OSTI)

During a 24-h period, beginning 1200 UTC 11 May 1982, a series of mesoscale convective systems developed within a weakly forced large-scale environment. Two of these systems had a large component of motion against the midtropospheric flow and ...

David J. Stensrud; J. Michael Fritsch

1994-09-01T23:59:59.000Z

373

simulations  

E-Print Network (OSTI)

Part 1 of this two-part paper describes the analysis and 2D finite element (FE) simulations for a capacitive incremental position sensor for nanopositioning of microactuator systems with a displacement range of 100 m or more. Two related concepts for a capacitive incremental position sensor are presented. In an incremental capacitance measurement mode (ICMM), the periodic change in capacitance is measured to determine the relative displacement between two periodic geometries S1 and S2 with a gap distance of ?1 m. In a constant capacitance measurement mode (CCMM), the distance between S1 and S2 is controlled to keep the capacitance between S1 and S2 constant. Analysis and 2D finite element simulations show that the signal-to-noise ratio for CCMM can be>300 over ICMM and with less nonlinearity of the position sensor signal. This means that CCMM will perform better in accurate quadrature incremental position detection. A comparison with measurements shows that the 2D finite element simulation method is a useful tool that realistically predicts the capacitance versus displacement for different combinations of periodic geometries. (Some figures in this article are in colour only in the electronic version) 1.

A A Kuijpers; G J M Krijnen; R J Wiegerink; T S J Lammerink; M Elwenspoek

2006-01-01T23:59:59.000Z

374

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

E-Print Network (OSTI)

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

Pradipta, Rezy

2012-01-01T23:59:59.000Z

375

Determining Meaningful Differences for SMACEX Eddy Covariance Measurements  

Science Conference Proceedings (OSTI)

Two eddy covariance instrument comparison studies were conducted before and after the Soil MoistureAtmosphere Coupling Experiment (SMACEX) field campaign to 1) determine if observations from multiple sensors were equivalent for the measured ...

D. W. Meek; J. H. Prueger; W. P. Kustas; J. L. Hatfield

2005-12-01T23:59:59.000Z

376

Estimating Suppression of Eddy Mixing by Mean Flows  

Science Conference Proceedings (OSTI)

Particle- and tracer-based estimates of lateral diffusivities are used to estimate the suppression of eddy mixing across strong currents. Particles and tracers are advected using a velocity field derived from sea surface height measurements from ...

Andreas Klocker; Raffaele Ferrari; Joseph H. LaCasce

2012-09-01T23:59:59.000Z

377

Comparison of Eddies off the North Brazilian and Somali Coasts  

Science Conference Proceedings (OSTI)

Repeated temperature sections using XBTs from ships of opportunity along the sea lane off the Brazilian coast indicate that a region of mesoscale occurs in which the eddies are particularly well developed in northern summer and fall. These are ...

J. G. Bruce

1984-04-01T23:59:59.000Z

378

Objective Detection of Oceanic Eddies and the Agulhas Leakage  

Science Conference Proceedings (OSTI)

Mesoscale oceanic eddies are routinely detected from instantaneous velocities derived from satellite altimetry data. While simple to implement, this approach often gives spurious results and hides true material transport. Here it is shown how ...

Francisco J. Beron-Vera; Yan Wang; Mara J. Olascoaga; Gustavo J. Goni; George Haller

2013-07-01T23:59:59.000Z

379

A Numerical Study of Loop Current Intrusions and Eddy Shedding  

Science Conference Proceedings (OSTI)

The dynamics of the eddy shedding by the Loop Current in the Gulf of Mexico have been investigated using three nonlinear numerical models: two-layer, barotropic and reduced gravity. The barotropic and reduced gravity models demonstrate the ...

H. E. Hurlburt; J. Dana Thompson

1980-10-01T23:59:59.000Z

380

The Influence of an Upper Thermocline Current on Intrathermocline Eddies  

Science Conference Proceedings (OSTI)

In this study, the effect of an upper-layer current on the propagation of intermediate vortices, such as Mediterranean Water eddies, is investigated. The author discusses the advection mechanism proposed by Hogg and Stommel and shows how the ...

Y. G. Morel

1995-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Thermally Driven and Eddy-Driven Jet Variability in Reanalysis  

Science Conference Proceedings (OSTI)

Two important dynamical processes influence the extratropical zonal wind field: angular momentum transport by the thermally direct Hadley circulation (thermal-driving T) and momentum flux convergence by atmospheric waves (eddies) that develop in ...

Camille Li; Justin J. Wettstein

2012-03-01T23:59:59.000Z

382

Application of Oxygen Eddy Correlation in Aquatic Systems  

Science Conference Proceedings (OSTI)

The eddy correlation technique is rapidly becoming an established method for resolving dissolved oxygen fluxes in natural aquatic systems. This direct and noninvasive determination of oxygen fluxes close to the sediment by simultaneously ...

Claudia Lorrai; Daniel F. McGinnis; Peter Berg; Andreas Brand; Alfred West

2010-09-01T23:59:59.000Z

383

Lateral Mixing in the Pycnocline by Baroclinic Mixed Layer Eddies  

Science Conference Proceedings (OSTI)

Using a process study model, the effect of mixed layer submesoscale instabilities on the lateral mixing of passive tracers in the pycnocline is explored. Mixed layer eddies that are generated from the baroclinic instability of a front within the ...

Gualtiero Badin; Amit Tandon; Amala Mahadevan

2011-11-01T23:59:59.000Z

384

Seasonality in Southern Hemisphere Eddy Statistics at 500 mb  

Science Conference Proceedings (OSTI)

An analysis has been made of the spatial and frequency dependence of transient eddy statistics in the Southern Hemisphere at 500 mb. This study emphasizes summer versus winter differences in order to complement previous results of Trenberth (1981)...

Kevin E. Trenberth

1982-11-01T23:59:59.000Z

385

Eddy Asymmetry in the Sheared Heated Boundary Layer  

Science Conference Proceedings (OSTI)

Statistical measures are developed to study the influence of mean shear on the asymmetry of eddy updrafts as observed from low-level aircraft flights in HAPEX, FIFE, and SESAME. This asymmetry involves formation of microfronts between updrafts ...

L. Mahrt

1991-02-01T23:59:59.000Z

386

Eddy Heat Flux in the Subtropical North Pacific  

Science Conference Proceedings (OSTI)

Meridional eddy heat flux in the subtropical North Pacific is estimated from TRANSPAC ship-of-opportunity data collected during 197680. Two methods are used. The first fits simple functional forms to be temporal anomalies of the temperature ...

Andrew F. Bennett; Warren B. White

1986-04-01T23:59:59.000Z

387

Sources of Eddy Kinetic Energy in the Labrador Sea  

Science Conference Proceedings (OSTI)

Experiments with a suite of North Atlantic general circulation models are used to examine the sources of eddy kinetic energy (EKE) in the Labrador Sea. A high-resolution model version (112) quantitatively reproduces the observed signature. A ...

Carsten Eden; Claus Bning

2002-12-01T23:59:59.000Z

388

Long-Term Evolution of Elongated Warm Eddies  

Science Conference Proceedings (OSTI)

The purpose of this research is to investigate the evolution of elongated warm eddies. A shallow-water, reduced-gravity, primitive equation model is used to perform a multicase numerical experiment, which includes vortices of very different ...

Edgar G. Pava; Manuel Lpez

1994-10-01T23:59:59.000Z

389

Analysis of Inadvertent Microprocessor Lag Time on Eddy Covariance Results  

Science Conference Proceedings (OSTI)

Researchers using the eddy covariance approach to measuring trace gas fluxes are often hoping to measure carbon dioxide and energy fluxes for ecosystem intercomparisons. This paper demonstrates a systematic microprocessor-caused lag of ?0.1 to ?...

Karl Zeller; Gary Zimmerman; Ted Hehn; Evgeny Donev; Diane Denny; Jeff Welker

2001-09-01T23:59:59.000Z

390

Direct Atmospheric Forcing of Geostrophic Eddies. Part II: Coherence Maps  

Science Conference Proceedings (OSTI)

The theory of stochastic atmospheric forcing of quasigeostrophic eddies is applied to calculate coherence maps, that is, the coherence between the oceanic response at one location and the atmospheric forcing at another location as a function of ...

Angelika Lippert; Peter Mller

1995-01-01T23:59:59.000Z

391

Eddies at the Subtropical Convergence South of Africa  

Science Conference Proceedings (OSTI)

A descriptive analysis of the occurrence and kinematics of mesoscale eddies at the subtropical convergence south of Africa is presented. Data used in this study include thermal infrared imagery from satellites since 1978 and a number of ...

J. R. E. Lutjeharms; H. R. Valentine

1988-05-01T23:59:59.000Z

392

Eddy sensors for small diameter stainless steel tubes.  

SciTech Connect

The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

2011-08-01T23:59:59.000Z

393

An Eddy Resolving Numerical Model of the Ventilated Thermocline  

Science Conference Proceedings (OSTI)

A three-dimensional, primitive equation numerical model is used to study the effects of mesoscale eddies within the subtropical thermocline. Solutions are obtained for an ocean bounded by idealized topography are driven by simple wind and ...

Michael D. Cox

1985-10-01T23:59:59.000Z

394

Poleward Buoyancy Transport in the Ocean and Mesoscale Eddies  

Science Conference Proceedings (OSTI)

There are many dynamic similarities between mesoscale eddies in the ocean, and cyclones and anticyclones in the earth's atmosphere. Observational data, however, are still not adequate to explore this analogy in detail. In the present study a new ...

Kirk Bryan

1986-05-01T23:59:59.000Z

395

On spectral analysis of mesoscale eddies. Part I: Linear analysis  

Science Conference Proceedings (OSTI)

This study aims to understand the ocean circulation, which is characterized by the presence of multiple alternating zonal jets and transient mesoscale eddies, by systematic analysis of the underlying linear dynamics of this system. For this ...

P. Berloff; I. Kamenkovich

396

Cyclonic Eddies in the Eastern Gulf of Mexico  

Science Conference Proceedings (OSTI)

Cold-domed cyclonic eddies juxtaposed to the cyclonic shear side of the Gulf Loop Current are observed in simultaneously obtained hydrographic, current meter mooring, and satellite infrared data. The cyclones are initially observed in the ...

Fred M. Vukovich; George A. Maul

1985-01-01T23:59:59.000Z

397

Loop Current Eddy Paths in the Western Gulf of Mexico  

Science Conference Proceedings (OSTI)

The paths of anticyclonic Loop Current eddies in the western Gulf of Mexico have been investigated using ARGOS-tracked drifters accompanied by hydrographic surveys. The analysis used orbit parameters derived from a least square fit of a ...

Peter Hamilton; G. S. Fargion; D. C. Biggs

1999-06-01T23:59:59.000Z

398

Computational Simulation of a Heavy Vehicle Trailer Wake  

SciTech Connect

To better understand the flow mechanisms that contribute to the aerodynamic drag of heavy vehicles, unsteady large-eddy simulations are performed to model the wake of a truncated trailer geometry above a no-slip surface. The truncation of the heavy vehicle trailer is done to reduce the computational time needed to perform the simulations. Both unsteady and time-averaged results are presented from these simulations for two grids. A comparison of velocity fields with those obtained from a wind tunnel study demonstrate that there is a distinct di.erence in the separated wake of the experimental and computational results, perhaps indicating the influence of the geometry simplification, turbulence model, boundary conditions, or other aspects of the chosen numerical approach.

Ortega, J M; Dunn, T; McCallen, R; Salari, K

2002-12-04T23:59:59.000Z

399

Retrospective Eddy Current Defect Analysis of Degraded Fuel Rods  

Science Conference Proceedings (OSTI)

EPRIs Fuel Reliability Program is currently sponsoring post-irradiation examination (PIE) projects to develop a correlation between eddy current signals and features of interest in Zircaloy fuel cladding and channel materials. In this report, eddy current PIE data were retrospectively analyzed using Magnifi 2.0 R3 software for comparison to other PIE data for five domestic BWR fuel rods with varying degrees of corrosion, hydride formation, and cracking. One goal was to determine if newer ...

2013-11-14T23:59:59.000Z

400

The Formation of Oceanic Eddies in Symmetric and Asymmetric Jets. Part I: Early Time Evolution and Bulk Eddy Transports  

Science Conference Proceedings (OSTI)

A numerical study of the life cycles of eddies formed in perturbed baroclinic jets, emphasizing the influence of spanwise asymmetry in the initial structure of the jet on the downstream evolution of the flow, is presented. In particular, ...

Andrew B. G. Bush; James C. McWilliams; W. Richard Peltier

1995-09-01T23:59:59.000Z

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


401

Numerical simulation of flow distribution for pebble bed high temperature gas cooled reactors  

E-Print Network (OSTI)

The premise of the work presented here is to use a common analytical tool, Computational Fluid dynamics (CFD), along with a difference turbulence models. Eddy viscosity models as well as state-of-the-art Large Eddy Simulation (LES) were used to study the flow past bluff bodies. A suitable CFD code (CFX5.6b) was selected and implemented. Simulation of turbulent transport for the gas through the gaps of the randomly distributed spherical fuel elements (pebbles) was performed. Although there are a number of numerical studies () on flows around spherical bodies, none of them use the necessary turbulence models that are required to simulate flow where strong separation exists. With the development of high performance computers built for applications that require high CPU time and memory; numerical simulation becomes one of the more effective approaches for such investigations and LES type of turbulence models can be used more effectively. Since there are objects that are touching each other in the present study, a special approach was applied at the stage of building computational domain. This is supposed to be a considerable improvement for CFD applications. Zero thickness was achieved between the pebbles in which fission reaction takes place. Since there is a strong pressure gradient as a result of high Reynolds Number on the computational domain, which strongly affects the boundary layer behavior, heat transfer in both laminar and turbulent flows varies noticeably. Therefore, noncircular curved flows as in the pebble-bed situatio n, in detailed local sense, is interesting to be investigated. Since a compromise is needed between accuracy of results and time/cost of effort in acquiring the results numerically, selection of turbulence model should be done carefully. Resolving all the scales of a turbulent flow is too costly, while employing highly empirical turbulence models to complex problems could give inaccurate simulation results. The Large Eddy Simulation (LES) method would achieve the requirements to obtain a reasonable result. In LES, the large scales in the flow are solved and the small scales are modeled. Eddy viscosity and Reynolds stress models were also be used to investigate the applicability of these models for this kind of flow past bluff bodies at high Re numbers.

Yesilyurt, Gokhan

2006-05-01T23:59:59.000Z

402

Detection of ultra high energy neutrinos with an underwater very large volume array of acoustic sensors: A simulation study  

E-Print Network (OSTI)

This thesis investigates the detection of ultra high energy (E > 1 EeV) cosmic neutrinos using acoustic sensors immersed in water. The method is based on the thermoacoustic model describing the production of microsecond bipolar acoustic pulses by neutrino-induced particle cascades. These cascades locally heat the medium which leads to rapid expansion and a short sonic pulse detectable in water with hydrophones over distances of several kilometres. This makes acoustic detection an approach complementary to todays optical Cerenkov and radio Cerenkov detectors, and could help to reduce the respective systematic uncertainties. In this work a complete simulation / reconstruction chain for a submarine acoustic neutrino telescope is developed, and the sensitivity of such a detector to a diffuse flux of ultra highenergy cosmic neutrinos is estimated.

Timo Karg

2006-08-15T23:59:59.000Z

403

Simulations of electron-cloud heat load for the cold arcs of the CERN Large Hadron Collider and its high-luminosity upgrade scenarios  

E-Print Network (OSTI)

The heat load generated by an electron cloud in the cold arcs of the Large Hadron Collider (LHC) is a concern for operation near and beyond nominal beam current. We report the results of simulation studies, with updated secondary- emission models, which examine the severity of the electron heat load over a range of possible operation parameters, both for the nominal LHC and for various luminosity-upgrade scenarios, such as the so-called full crab crossing and early separation schemes, the large Piwinski angle scheme, and a variant of the latter providing compatibility with the (upgraded) LHCb experiment. The variable parameters considered are the maximum secondary-emission yield, the number of particles per bunch, and the spacing between bunches. In addition, the dependence of the heat load on the longitudinal bunch profile is investigated.

Maury Cuna, H; Zimmermann, F

2012-01-01T23:59:59.000Z

404

Large Lenses of Highly Saline Mediterranean Water  

Science Conference Proceedings (OSTI)

Isolated compact anticyclonic eddies or salt lenses were found in the Canary Basin. Hydrographic surveys of three such lenses show large anomalies of salinity and temperature (0.8, 2.5C). They are centered at 1100 m, have a vertical extent of ...

Laurence Armi; Walter Zenk

1984-10-01T23:59:59.000Z

405

Development of design and simulation model and safety study of large-scale hydrogen production using nuclear power.  

DOE Green Energy (OSTI)

Before this LDRD research, no single tool could simulate a very high temperature reactor (VHTR) that is coupled to a secondary system and the sulfur iodine (SI) thermochemistry. Furthermore, the SI chemistry could only be modeled in steady state, typically via flow sheets. Additionally, the MELCOR nuclear reactor analysis code was suitable only for the modeling of light water reactors, not gas-cooled reactors. We extended MELCOR in order to address the above deficiencies. In particular, we developed three VHTR input models, added generalized, modular secondary system components, developed reactor point kinetics, included transient thermochemistry for the most important cycles [SI and the Westinghouse hybrid sulfur], and developed an interactive graphical user interface for full plant visualization. The new tool is called MELCOR-H2, and it allows users to maximize hydrogen and electrical production, as well as enhance overall plant safety. We conducted validation and verification studies on the key models, and showed that the MELCOR-H2 results typically compared to within less than 5% from experimental data, code-to-code comparisons, and/or analytical solutions.

Gelbard, Fred; Oh, Seungmin (Purdue University, West Lafayette, IN); Rodriguez, Salvador B.; Revankar, Shripad T. (Purdue University, West Lafayette, IN); Gauntt, Randall O.; Cole, Randall K., Jr.; Espinosa, Flor (University of New Mexico, Albuquerque, NM); Drennen, Thomas E.; Tournier, Jean-Michel (University of New Mexico, Albuquerque, NM); Hogan, Kevin (Texas A& M University, College Station, TX); Archuleta, Louis (OMICRON Safety and Risk, Inc., Albuquerque, NM); Malczynski, Leonard A.; Vierow, Karen (Texas A& M University, College Station, TX); McFadden, Katherine Letizia; Martin, William Joseph; El-Genk, Mohamed S. (University of New Mexico, Albuquerque, NM); Louie, David L. Y. (OMICRON Safety and Risk, Inc., Albuquerque, NM)

2007-10-01T23:59:59.000Z

406

Progress on the development of a three-dimensional capability for simulating large-scale complex geologic processes  

Science Conference Proceedings (OSTI)

Significant progress has been made in developing a three-dimensional capability for predicting the mechanical response of rock over spatial and time scales of geologic interest to the Oil and Gas industry. An Advanced Computational Technology Initiative (ACTI) initiated three years ago to achieve such a computational technology breakthrough has made significant progress towards its goal by adapting and improving the unique advanced quasistatic finite element technology developed by Sandia National Laboratories to the mechanics applications important to exploration and production (E and P). This capability now gives the industry a powerful tool to help reduce risk on prospects, improve pre-project initial reserve estimates, and lower operating costs. Progress to date on this program is reported herein by presenting and discussing the enhancements and adaptations that have been made to the technology, with specific examples to illustrate their use on large E and P geomechanics problems.

Argueello, J.G.; Stone, C.M.; Fossum, A.F.

1998-02-01T23:59:59.000Z

407

Large Scale Atmospheric Chemistry Simulations for 2001: An Analysis of Ozone and Other Species in Central Arizona  

DOE Green Energy (OSTI)

A key atmospheric gas is ozone. Ozone in the stratosphere is beneficial to the biosphere because it absorbs a significant fraction of the sun's shorter wavelength ultraviolet radiation. Ozone in the troposphere is a pollutant (respiratory irritant in humans and acts to damage crops, vegetation, and many materials). It affects the Earths energy balance by absorbing both incoming solar radiation and outgoing long wave radiation. An important part of the oxidizing capacity of the atmosphere involves ozone, through a photolysis pathway that leads to the hydroxyl radical (OH). Since reaction with OH is a major sink of many atmospheric species, its concentration controls the distributions of many radiatively important species. Ozone in the troposphere arises from both in-situ photochemical production and transport from the stratosphere. Within the troposphere, ozone is formed in-situ when carbon monoxide (CO), methane (CH4), and non-methane hydrocarbons (NMHCs) react in the presence of nitrogen oxides (NO, = NO + NO2) and sunlight. The photochemistry of the stratosphere differs significantly from that in the troposphere. Within the stratosphere, ozone formation is initiated by the photolysis of 02. Stratospheric ozone may be destroyed via catalytic reactions with NO, H (hydrogen), OH, CI (chlorine) and Br (bromine), or photolysis. In the past, attempts to simulate the observed distributions of ozone (and other important gases) have focused on either the stratosphere or the troposphere. Stratospheric models either employed simplified parameterizations to represent tropospheric chemical and physical processes, or assumed the troposphere behaved as a boundary condition. Likewise, tropospheric models used simplified stratospheric chemistry and transport.

Atherton, C; Bergmann, D; Cameron-Smith, P; Connell, P; Molenkamp, C; Rotman, D; Tannahil, J

2002-10-08T23:59:59.000Z

408

New Eddy Correlation System for ARM SGP Site  

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

New Eddy Correlation System for ARM SGP Site New Eddy Correlation System for ARM SGP Site M. S. Pekour Argonne National Laboratory Argonne, Illinois Background Eddy correlation (ECOR) systems are widely used for in situ measurement of the turbulent fluxes in the atmosphere. The ECOR technique is the most direct method for determining fluxes; vertical fluxes are obtained by correlating the vertical wind component with the horizontal wind component (momentum flux), temperature (sensible heat flux), water vapor density (latent heat flux), and a scalar admixture density (e.g., CO 2 flux). Typically, an ultrasonic anemometer-thermometer ("sonic anemometer") is used for rapid, high-precision, three-dimensional (3D) wind measurements, as well as for temperature fluctuation measurements. A fast-response humidity sensor, such as an infra-red gas analyzer (IRGA) is

409

Microsoft Word - Eddy-LeaCommission20030618.doc  

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

June 18, 2003 June 18, 2003 Department of Energy Awards Eddy/Lea Regional Commission $300,000 Grant WASHINGTON, DC - Secretary of Energy Spencer Abraham announced today that the Department of Energy will award $300,000 to the Eddy/Lea Regional Commission, the community reuse organization (CRO) for southern New Mexico. This grant will fund part of the commission's operating costs, as well as other specific projects, including continuing the business expansion and retention of a 28-block downtown area and assisting in efforts to create new jobs by recruiting new business and industry. "The Energy Department is a good neighbor to the communities surrounding our sites," Secretary Abraham said. "We will continue to work with the Eddy/Lea Regional Commission and

410

Eddy Current Testing for Detecting Small Defects in Thin Films  

SciTech Connect

Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.

Obeid, Simon; Tranjan, Farid M. [Electrical and Computer Engineering Department, UNCC (United States); Dogaru, Teodor [Albany Instruments, 426-O Barton Creek, Charlotte, NC 28262 (United States)

2007-03-21T23:59:59.000Z

411

Role of Parameterized Eddies in the Energy Budget of the Global Thermohaline Circulation: Cabbeling versus Restratification  

Science Conference Proceedings (OSTI)

The gravitational potential energy (GPE) budget of the global thermohaline circulation is investigated with a non-eddy-resolving model under a realistic configuration. The model incorporates parameterizations for mesoscale eddies and an equation ...

L. Shogo Urakawa; Hiroyasu Hasumi

2010-08-01T23:59:59.000Z

412

Eddy Shape, Orientation, Propagation, and Mean Flow Feedback in Western Boundary Current Jets  

Science Conference Proceedings (OSTI)

We revisit a study of eddy-mean flow interactions in an idealized model of a Western Boundary Current Extension jet using properties of the horizontal velocity correlation tensor to diagnose characteristics of average eddy shape, orientation, ...

Stephanie Waterman; Brian J. Hoskins

413

The Interaction of Horizontal Eddy Transport and Thermal Drive in the Stratosphere  

Science Conference Proceedings (OSTI)

The interaction of horizontal eddy motions and thermal drive in the stratosphere is investigated in equivalent barotropic calculations on the sphere. Eddy advection tends to homogenize the distribution of potential vorticity Q while thermal ...

Murry L. Salby; Rolando R. Garcia; Donal O'sullivan; Patrick Callaghan

1990-07-01T23:59:59.000Z

414

Barotropic Dynamics of Interactions between Synoptic and Low-Frequency Eddies  

Science Conference Proceedings (OSTI)

The interaction of low-frequency and synoptic eddies is studied by diagnosing the time-averaged transport of vorticity by linear, transient eddies propagating on a basic state that includes a stationary wave. An analytic calculation assuming a ...

Jianchun Qin; Walter A. Robinson

1992-01-01T23:59:59.000Z

415

On the Linear Relationship between Loop Current Retreat Latitude and Eddy Separation Period  

Science Conference Proceedings (OSTI)

A linear correlation exists between the retreat latitude of the Loop Current following eddy separation and the subsequent eddy separation period. This empirical relationship was first identified in satellite altimeter-derived Loop Current ...

Alexis Lugo-Fernndez; Robert R. Leben

2010-12-01T23:59:59.000Z

416

Eddy-Driven Buoyancy Gradients on Eastern Boundaries and Their Role in the Thermocline  

Science Conference Proceedings (OSTI)

It is demonstrated that eddy fluxes of buoyancy at the eastern and western boundaries maintain alongshore buoyancy gradients along the coast. Eddy fluxes arise near the eastern and western boundaries because on both coasts buoyancy gradients ...

Paola Cessi; Christopher L. Wolfe

2009-07-01T23:59:59.000Z

417

Equatorial Pacific 13C Water Eddies in the Eastern Subtropical South Pacific Ocean  

Science Conference Proceedings (OSTI)

Argo float profile data are used to analyze warm, salty, weakly stratified, subthermocline eddies of tropical origin in the eastern subtropical South Pacific Ocean. These eddies contain anomalous signatures of the equatorial Pacific 13C Water ...

Gregory C. Johnson; Kristene E. McTaggart

2010-01-01T23:59:59.000Z

418

Proposed Action and Alternatives 2-40 Big Eddy-Knight Transmission...  

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

Transmission Project Final EIS July 2011 Figure 2-18. View of BPA's Big Eddy Substation from Columbia View Drive (looking east) Figure 2-19. View of Entrance to Big Eddy...

419

Two-Layer Baroclinic Eddy Heat Fluxes: Zonal Flows and Energy Balance  

Science Conference Proceedings (OSTI)

The eddy heat flux generated by statistically equilibrated baroclinic turbulence supported on a uniform, horizontal temperature gradient is examined using a two-layer ?-plane quasigeostrophic model. The dependence of the eddy diffusivity of ...

Andrew F. Thompson; William R. Young

2007-09-01T23:59:59.000Z

420

Laboratory Experiments on Eddy Generation by a Buoyant Coastal Current Flowing over Variable Bathymetry  

Science Conference Proceedings (OSTI)

Irminger rings are warm-core eddies formed off the west coast of Greenland. Recent studies suggest that these eddies, which are implicated in the rapid springtime restratification of the Labrador Sea, are formed by an internal instability of the ...

Christopher L. Wolfe; Claudia Cenedese

2006-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Eddy Energetics in the Upper Equatorial Pacific during the Hawaii-to-Tahiti Shuttle Experiment  

Science Conference Proceedings (OSTI)

Eddy energetics in the central equatorial Pacific Ocean is examined using Acoustic Doppler Current Profiler velocities and CTD densities collected during the Hawaii-to-Tahiti Shuttle Experiment, in 197980. Three distinct sources of eddy energy ...

Douglas S. Luther; Eric S. Johnson

1990-07-01T23:59:59.000Z

422

The Catalina Eddy and its Effect on Pollution over Southern California  

Science Conference Proceedings (OSTI)

A case study of a Catalina Eddy during Project BASIN is presented. There appears to he a topographic influence in the generation of this eddy. Detailed surface and upper-air data over Los Angeles illustrate the effect of the eddy on the boundary ...

Roger M. Wakimoto

1987-04-01T23:59:59.000Z

423

An exercise in forecasting loop current and eddy frontal positions in the Gulf of Mexico  

E-Print Network (OSTI)

An exercise in forecasting loop current and eddy frontal positions in the Gulf of Mexico L.-Y. Oey to forecast Loop Current and Loop Current eddy frontal positions in the Gulf of Mexico, the Princeton Regional (2005), An exercise in forecasting loop current and eddy frontal positions in the Gulf of Mexico

424

Eddy-current system for the vibration-testing of blades  

SciTech Connect

This invention is an improved system for the vibration-testing of cantilevered non-ferrous articles by inducing eddy currents therein. The principal advantage of the system is that relatively little heat is generated in the article being vibrated. Thus, a more accurate measurement of the fatigue characteristics of the article is obtained. Furthermore, the generation of relatively little heat in the blade permits tests to be conducted in low-pressure atmospheres simulating certain actual processes environments. Heat-generation in the vibrated article is minimized by utilizing eddy currents which are generated by an electromagnet whose magnetic field varies but does not change polarity. The typical winding for the electromagnet is excited with pulsating d.c. That is, the winding is alternately charged by connecting it across a d.c. power supply and then discharged by connecting it across a circuit for receiving current generated in the winding by self-induction. Preferably, the discharge circuit is designed so that the waveform of the discharging current approximates that of the charging current.

Jacobs, Martin E. (Chillicothe, OH)

1977-01-01T23:59:59.000Z

425

Abyssal Eddy Kinetic Energy Levels in the Western North Pacific  

Science Conference Proceedings (OSTI)

An earlier observation of about 50 cm2 s?2 for the maximum abyssal (4000 m depth) eddy kinetic energy (KE) in the western North Pacific along 152E, occurring in the vicinity of the Kuroshio Extension, is now supported by nearly two years of ...

Willeam J. Schmitz Jr.

1984-01-01T23:59:59.000Z

426

MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS  

E-Print Network (OSTI)

(SPMSM); interior magnet PM motors; time-stepped ¯nite-element analysis (FEA); thermal circuits in traditional motor design and analysis. However, due to the high conductivity of the rare-earth magnet, neody-element analysis (FEA) for the calculation of eddy current loss in the magnet. Based on the calculated losses

Mi, Chunting "Chris"

427

Why Can Wind Delay the Shedding of Loop Current Eddies?  

Science Conference Proceedings (OSTI)

It is first shown that wind in the Gulf of Mexico can delay the shedding of Loop Current eddies. A time-dependent, three-dimensional numerical experiment forced by a spatially and temporally constant westward wind stress within the Gulf is ...

Y.-L. Chang; L.-Y. Oey

2010-11-01T23:59:59.000Z

428

Coherent Eddies in the Labrador Sea Observed from a Mooring  

Science Conference Proceedings (OSTI)

During JuneNovember 1994, a mooring in the central Labrador Sea near the former Ocean Weather Station Bravo recorded a half-dozen anomalous events that prove to be two different types of coherent eddies. Comparisons with simple analytical models ...

Jonathan M. Lilly; Peter B. Rhines

2002-02-01T23:59:59.000Z

429

The Effect of the Ocean Eddy on Tropical Cyclone Intensity  

Science Conference Proceedings (OSTI)

The rapid intensification of Hurricane Katrina followed by the devastation of the U.S. Gulf States highlights the critical role played by an upper-oceanic thermal structure (such as the ocean eddy or Loop Current) in affecting the development of ...

Chun-Chieh Wu; Chia-Ying Lee; I-I. Lin

2007-10-01T23:59:59.000Z

430

Equilibration of an Atmosphere by Adiabatic Eddy Fluxes  

Science Conference Proceedings (OSTI)

A major question for climate studies is to quantify the role of turbulent eddy fluxes in maintaining the observed atmospheric mean state. Both the equator-to-pole temperature gradient and the static stability of the extra-tropical atmosphere are ...

Malte Jansen; Raffaele Ferrari

431

On the Influence of Bottom Topography on the Agulhas Eddy  

Science Conference Proceedings (OSTI)

A series of numerical experiments with a two-layer primitive equation model is presented to study the dynamics of Agulhas eddies. The main goal of the paper is to examine the influence of an underwater meridional ridge (modeled after the Walvis ...

Vladimir M. Kamenkovich; Yurii P. Leonov; Dmitrii A. Nechaev; Deirdre A. Byrne; Arnold L. Gordon

1996-06-01T23:59:59.000Z

432

PARABOLIC SUBGROUPS OF GARSIDE GROUPS II : EDDY GODELLE  

E-Print Network (OSTI)

PARABOLIC SUBGROUPS OF GARSIDE GROUPS II : RIBBONS EDDY GODELLE Abstract. We introduce parabolic subgroupoids and provide a groupoid presentation. In order to established the latter result, we subgroups, namely the standard parabolic subgroups, which are the subgroups generated by a subset

Paris-Sud XI, Université de

433

On the Use of Integrated Daylighting and Energy Simulations To Drive the Design of a Large Net-Zero Energy Office Building: Preprint  

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

522 522 August 2010 On the Use of Integrated Daylighting and Energy Simulations To Drive the Design of a Large Net-Zero Energy Office Building Preprint Rob Guglielmetti, Shanti Pless, and Paul Torcellini Presented at SimBuild 2010 New York, New York August 15-19, 2010 NOTICE The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC (Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. Accordingly, the US Government and Alliance retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. This report was prepared as an account of work sponsored by an agency of the United States government.

434

CgWind: A high-order accurate simulation tool for wind turbines and wind farms  

DOE Green Energy (OSTI)

CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

2010-02-22T23:59:59.000Z

435

V-TOUGH: An enhanced version of the TOUGH code for the thermal and hydrologic simulation of large-scale problems in nuclear waste isolation  

SciTech Connect

The TOUGH code developed at Lawrence Berkeley Laboratory (LBL) is being extensively used to numerically simulate the thermal and hydrologic environment around nuclear waste packages in the unsaturated zone for the Yucca Mountain Project. At the Lawrence Livermore National Laboratory (LLNL) we have rewritten approximately 80 percent of the TOUGH code to increase its speed and incorporate new options. The geometry of many problems requires large numbers of computational elements elements in order to realistically model detailed physical phenomena, and, as a result, large amounts of computer time are needed. In order to increase the speed of the code we have incorporated fast linear equation solvers, vectorization of substantial portions of code, improved automatic time stepping, and implementation of table look-up for the steam table properties. These enhancements have increased the speed of the code for typical problems by a factor of 20 on the Cray 2 computer. In addition to the increase in computational efficiency we have added several options: vapor pressure lowering; equivalent continuum treatments of fractures; energy and material volumetric, mass and flux accounting; and Stefan-Boltzmann radiative heat transfer. 5 refs.

Nitao, J.J.

1989-11-06T23:59:59.000Z

436

Moist Thermodynamics of the MaddenJulian Oscillation in a Cloud-Resolving Simulation  

Science Conference Proceedings (OSTI)

The moist thermodynamic processes that determine the time scale and energy of the MaddenJulian oscillation (MJO) are investigated using moisture and eddy available potential energy budget analyses on a cloud-resolving simulation. Two MJO episodes ...

Samson Hagos; L. Ruby Leung

2011-11-01T23:59:59.000Z

437

Numerical Simulations and a Conceptual Model of the Stratocumulus to Trade Cumulus Transition  

Science Conference Proceedings (OSTI)

A two-dimensional eddy-resolving model is used to study the transition from the stratocumulus topped boundary layer to the trade cumulus boundary layer. The 10-day simulations use an idealized Lagrangian trajectory representative of summertime ...

Matthew C. Wyant; Christopher S. Bretherton; Hugh A. Rand; David E. Stevens

1997-01-01T23:59:59.000Z

438

Microsoft Word - CX-BigEddy-Ostrander_WEB.doc  

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

4 4 SUBJECT: Environmental Clearance Memorandum Elizabeth Johnson - TFR-The Dalles Natural Resource Specialist Proposed Action: Perform routine access road maintenance within the Big Eddy-Ostrander No. 1 transmission line corridor Budget Information: Work Order # 00261716 PP&A Project No.: PP&A 1706 Categorical Exclusion Applied (from Subpart D, 10 C.F.R. Part 1021): B1.3, Routine maintenance activities...for structures, rights-of-way, infrastructures such as roads, equipment... routine maintenance activities, corrective....are required to maintain... infrastructures...in a condition suitable for a facility to be used for its designed purpose. Proposed by: Bonneville Power Administration (BPA) Location: The project area is located along BPA's Big Eddy-Ostrander No. 1 transmission line

439

Eddy County, New Mexico: Energy Resources | Open Energy Information  

Open Energy Info (EERE)

Eddy County, New Mexico: Energy Resources Eddy County, New Mexico: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 32.4170622°, -104.4723301° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":32.4170622,"lon":-104.4723301,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

440

Formation of thermal eddies during rf heating of plasma  

SciTech Connect

Moderate power (approx.1 kW) excitation of lower hybrid waves in a linear plasma column is found to increase the reflectivity of the phased waveguide exciter and to change the vertical position of the resonance cone. Probing of the plasma near the mouth of the waveguide reveals that the increased reflection results from an undulation in the plasma surface. We present evidence that this surface distortion is driven by thermal eddies associated with asymmetrical electron heating.

Motley, R.W.; Hooke, W.M.; Anania, G.

1979-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "large eddy simulation" 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

Evaluation of PC-Based Eddy Current Database Management Program  

Science Conference Proceedings (OSTI)

Part of the Balance-of-Plant (BOP) Heat Exchanger Condition Assessment Program for 1998 was an evaluation of commercially available PC-based eddy current database management software programs. The objective of the study was to evaluate the selected software programs for general user-friendliness, ease of tubesheet creation, inspection planning, query building and execution, printing options, import and export capabilities, documentation, network features, technical support, and product cost. Three (3) so...

1998-12-18T23:59:59.000Z

442

Automated Detection and Location of Indications in Eddy Current Signals  

DOE Patents (OSTI)

A computer implemented information extraction process that locates and identifies eddy current signal features in digital point-ordered signals, said signals representing data from inspection of test materials, by enhancing the signal features relative to signal noise, detecting features of the signals, verifying the location of the signal features that can be known in advance, and outputting information about the identity and location of all detected signal features.

Brudnoy, David M.; Oppenlander, Jane E.; Levy, Arthur J.

1998-06-30T23:59:59.000Z

443

Surface Layer Transport of Sulfate Particles in the Western United States by the Large-Scale Wind Field  

Science Conference Proceedings (OSTI)

The transport patterns of fine sulfur aerosols in the western United States are shown. The large-scale resultant horizontal flux was computed in terms of that contributed by the mean flux versus that contributed by a turbulence, or eddy, ...

Lowell L. Ashbaugh; Leonard O. Myrup; Robert G. Flocchini

1984-05-01T23:59:59.000Z

444

Differential rotation in solar-like stars from global simulations  

E-Print Network (OSTI)

To explore the physics of large-scale flows in solar-like stars, we perform 3D anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit large-eddy simulation approach designed to capture effects from non-resolved small scales. We obtain two regimes of differential rotation, with equatorial zonal flows accelerated either in the direction of rotation (solar-like) or in the opposite direction (anti-solar). While the models with the solar-like differential rotation tend to produce multiple cells of meridional circulation, the models with anti-solar differential rotation result in only one or two meridional cells. Our simulations indicate that the rotation and large-scale flow patterns critically depend on the ratio between buoyancy and Coriolis forces. By including a subadiabatic layer at the bottom of the domain, corresponding to the stratification of a radiative zone, we reproduce a layer of strong radial shear...

Guerrero, G; Kosovichev, A G; Mansour, N N

2013-01-01T23:59:59.000Z

445

Steam Generator Management Program: Effect of Eddy Current Noise on Sizing Steam Generator Tube Degradation  

Science Conference Proceedings (OSTI)

The Electric Power Research Institutes (EPRIs) Steam Generator Management Program (SGMP) has developed procedures and tools to assist utility engineers in understanding the probability of detection (POD) in steam generator eddy current data in the presence of noise. Under some circumstances, eddy current noise can mask flaws that should be detected and assessed for tube integrity. This project focused on the ability to accurately size crack-like indications in the presence of eddy ...

2013-11-11T23:59:59.000Z

446

RELAP5/MOD3 simulation of the loss of residual heat removal during midloop operation experiment conducted at the ROSA-IV/ Large Scale Test Facility  

E-Print Network (OSTI)

The modeling of the complex thermal hydraulics Of reactor systems involves the use Of experimental test systems as well as numerical codes. A simulation of the loss of residual heat removal (RHR) during midloop operations was performed using the RELAP5/MOD3 thermal hydraulic code. The experiment was conducted at the Rig of Safety Assessment (ROSA)-IV/ Large Scale Test Facility (LSTF). The experiment involved a 5% cold leg break along with the loss of the RHR system-The transient was simulated for 3040 seconds. The ROSA-1-V/]LsTF is one of the largest test facilities in the world and is located in Japan. It is a volumetrically scaled (1/48) full height, two loop model of a Westinghouse four loop pressurized water reactor (PWR). The facility consists of pressure vessel, two symmetric loops, a pressurizer and a full emergency core cooling system (ECCS) system. The transient was run on the CRAY-YMP supercomputer at Texas A&M university. Core boiling and primary pressurization followed the initiation of the transient. The time to core boiling was overpredicted. Almost all Primary parameters were predicted well until the occurrence of the loop seal clearing (LSC) at 2400 seconds. The secondary side temperatures were in good agreement with the experimental data until the LSC. Following the LSC, the steam condensation in the tubes was not calculated. This resulted in the overprediction of primary pressures after the LSC. Also, the temperatures in the hot and the cold legs were overpredicted. Because there was no significant condensation in the U-tubes, the core remained uncovered. Moreover, the LSC did not recover. Consequently, secondary side temperatures were underpredicted after the LSC. This indicated the deficiency of the condensation model. The core temperature excursion at the time of the LSC was not predicted, though there was good agreement between the experimental and calculated data for the rest of the transient. Severe oscillations were calculated throughout the course of the transient. Overall, there was reasonable qualitative agreement between the measured and the calculated data.

Banerjee, Sibashis Sanatkumar

1994-01-01T23:59:59.000Z

447

Simulating Collisions for Hydrokinetic Turbines  

SciTech Connect

Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.

Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.

2013-10-01T23:59:59.000Z

448

Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain...  

Open Energy Info (EERE)

Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain, California- Performance Evaluation And Role Of Meteorological Forcing Jump to: navigation, search GEOTHERMAL...

449

Microsoft Word - CX-BigEddy-RedmondWoodPoles_WEB.doc  

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

Clearance Memorandum Darrell Aaby Line Foreman III - TFDF-Redmond Proposed Action: Wood pole replacements at select locations along the Big Eddy-Redmond and Redmond-Pilot...

450

Toward Convective Boundary Layer Parameterization: A Scalar Transport Module  

Science Conference Proceedings (OSTI)

Recent results from large-eddy simulations indicate that the eddy diffusivity for scalar diffusion through the top of a convective boundary layer is different from that for diffusion through the bottom. From this, one can show that the eddy ...

John C. Wyngaard

1984-06-01T23:59:59.000Z

451

Performance of powder-filled evacuated panel insulation in a manufactured home roof cavity: Tests in the Large Scale Climate Simulator  

SciTech Connect

A full-scale section of half the top of a single-wide manufactured home has been studied in the Large Scale Climate Simulator (LSCS) at the Oak Ridge National Laboratory. A small roof cavity with little room for insulation at the eaves is often the case with single-wide units and limits practical ways to improve thermal performance. The purpose of the current tests was to obtain steady-state performance data for the roof cavity of the manufactured home test section when the roof cavity was insulated with fiberglass batts, blown-in rock wool insulation or combinations of these insulations and powder-filled evacuated panel (PEP) insulation. Four insulation configurations were tested: (A) a configuration with two layers of nominal R{sub US}-7 h {center_dot} ft{sup 2} {center_dot} F/BTU (R{sub SI}-1.2 m{sup 2} {center_dot} K/W) fiberglass batts; (B) a layer of PEPs and one layer of the fiberglass batts; (C) four layers of the fiberglass batts; and (D) an average 4.1 in. (10.4 cm) thick layer of blown-in rock wool at an average density of 2.4 lb/ft{sup 3} (38 kg/m{sup 3}). Effects of additional sheathing were determined for Configurations B and C. With Configuration D over the ceiling, two layers of expanded polystyrene (EPS) boards, each about the same thickness as the PEPs, were installed over the trusses instead of the roof. Aluminum foils facing the attic and over the top layer of EPS were added. The top layer of EPS was then replaced by PEPs.

Petrie, T.W.; Kosny, J.; Childs, P.W.

1996-03-01T23:59:59.000Z

452

The Role of Eddies in Determining the Structure and Response of the Wind-Driven Southern Hemisphere Overturning: Results from the Modeling Eddies in the Southern Ocean (MESO) Project  

Science Conference Proceedings (OSTI)

The Modeling Eddies in the Southern Ocean (MESO) project uses numerical sensitivity studies to examine the role played by Southern Ocean winds and eddies in determining the density structure of the global ocean and the magnitude and structure of ...

Robert Hallberg; Anand Gnanadesikan

2006-12-01T23:59:59.000Z

453

The Role of Eddy-Tansport in the Thermohaline Circulation  

SciTech Connect

Several research themes were developed during the course of this project. (1) Low-frequency oceanic varibility; (2) The role of eddies in the Antarctic Circumpolar Current (ACC) region; (3) Deep stratification and the overturning circulation. The key findings were as follows: (1) The stratification below the main thermocline (at about 500m) is determined in the circumpolar region and then communicated to the enclosed portions of the oceans through the overturning circulation. (2) An Atlantic pole-to-pole overturning circulation can be maintained with very small interior mixing as long as surface buoyancy values are shared between the northern North Atlantic and the ACC region.

Dr. Paola Cessi

2011-11-17T23:59:59.000Z

454

Methods of and apparatus for levitating and eddy current probe  

DOE Patents (OSTI)

An eddy current probes is supported against the force of gravity with an air bearing while being urged horizontally toward the specimen being examined by a spring and displaced horizontally against the force of the spring pneumatically. The pneumatic displacement is accomplished by flowing air between a plenum chamber fixed with respect to the probe and the surface of the specimen. In this way, the surface of the specimens can be examined without making mechanical contact therewith while precisely controlling the distance at which the probe stands-off from the surface of the specimen. 4 figs.

Stone, W.J.

1986-01-01T23:59:59.000Z

455

Methods of and apparatus for levitating an eddy current probe  

DOE Patents (OSTI)

An eddy current probe is supported against the force of gravity with an air earing while being urged horizontally toward the specimen being examined by a spring and displaced horizontally against the force of the spring pneumatically. The pneumatic displacement is accomplished by flowing air between a plenum chamber fixed with respect to the probe and the surface of the specimen. In this way, the surface of the specimen can be examined without making mechanical contact therewith while precisely controlling the distance at which the probe stands-off from the surface of the specimen.

Stone, William J. (Kansas City, MO)

1988-05-03T23:59:59.000Z

456

Eddy Resolution versus Eddy Diffusion in a Double Gyre GCM. Part II: Mixing of Passive Tracers  

Science Conference Proceedings (OSTI)

The parameterization of the effect of the unresolved scales of motion on a passive tracer field in large-scale numerical ocean models is analyzed through a combination of Lagrangian and Eulerian velocities. The primitive equation isopycnal model ...

Horacio A. Figueroa

1994-02-01T23:59:59.000Z

457

An Exploration of the Role of Transient Eddies in Determining the Transport of a Zonally Reentrant Current  

Science Conference Proceedings (OSTI)

The meridional Ekman transport in a zonally reentrant channel may be balanced by diabatic circulations, standing eddies associated with topography, or by Lagrangian mean eddy mass fluxes. A simple model is used to explore the interaction between ...

Robert Hallberg; Anand Gnanadesikan

2001-11-01T23:59:59.000Z

458

Barotropic Impacts of Surface Friction on Eddy Kinetic Energy and Momentum Fluxes: An Alternative to the Barotropic Governor  

Science Conference Proceedings (OSTI)

As the surface drag is increased in a comprehensive general circulation model (GCM), the upper-level zonal winds decrease and eddy momentum flux convergence into the jet core increases. Globally averaged eddy kinetic energy decreases, a response ...

Elizabeth A. Barnes; Chaim I. Garfinkel

2012-10-01T23:59:59.000Z

459

A Barotropic Envelope Rossby Soliton Model for BlockEddy Interaction. Part III: Wavenumber Conservation Theorems for Isolated Blocks and Deformed Eddies  

Science Conference Proceedings (OSTI)

In a series of previous papers, an envelope Rossby soliton theory was formulated to investigate the interaction between a preexisting planetary wave and synoptic-scale eddies leading to a typical blocking flow. In this paper, numerical and ...

Dehai Luo

2005-11-01T23:59:59.000Z

460

Deep Eddy Energy and Topographic Rossby Waves in the Gulf of Mexico  

Science Conference Proceedings (OSTI)

Observations suggest the hypothesis that deep eddy kinetic energy (EKE) in the Gulf of Mexico can be accounted for by topographic Rossby waves (TRWs). It is presumed that the TRWs are forced by Loop Current (LC) pulsation, Loop Current eddy (LCE) ...

L-Y. Oey; H-C. Lee

2002-12-01T23:59:59.000Z

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


461

Parameterization Improvements in an Eddy-Permitting Ocean Model for Climate  

Science Conference Proceedings (OSTI)

Different parameterizations for vertical mixing and the effects of ocean mesoscale eddies are tested in an eddy-permitting ocean model. It has a horizontal resolution averaging about 0.7 and was used as the ocean component of the parallel ...

Peter R. Gent; Anthony P. Craig; Cecilia M. Bitz; John W. Weatherly

2002-06-01T23:59:59.000Z

462

On the Cylinder Collapse Problem, Mixing, and the Merger of Isolated Eddies  

Science Conference Proceedings (OSTI)

The Rossby adjustment of an initially circular column of water, the so-called collapse of a cylinder, continues to be a widely used method for forming lenslike eddies in the laboratory. Here, we consider the structure of an eddy so formed as well ...

William K. Dewar; Peter D. Killworth

1990-10-01T23:59:59.000Z

463

Structure and Origin of a Small Cyclonic Eddy Observed during the POLYMODE Local Dynamics Experiment  

Science Conference Proceedings (OSTI)

In the POLYMODE Local Dynamics Experiment (31N; 69.5W) a small cyclonic eddy was discovered and mapped. The eddy was characterized by an upward doming of isotherms in the upper part of the main thermocline. The dynamical signal extended from ...

Eric J. Lindstrom; Curtis C. Ebbesmeyer; W. Brechner Owens

1986-03-01T23:59:59.000Z

464

Eddy Heat Flux in the Southern Ocean: Response to Variable Wind Forcing  

Science Conference Proceedings (OSTI)

The authors assess the role of time-dependent eddy variability in the Antarctic Circumpolar Current (ACC) in influencing warming of the Southern Ocean. For this, an eddy-resolving quasigeostrophic model of the wind-driven circulation is used, and ...

Andrew Mc C. Hogg; Michael P. Meredith; Jeffrey R. Blundell; Chris Wilson

2008-02-01T23:59:59.000Z

465

Mixed Layer Lateral Eddy Fluxes Mediated by AirSea Interaction  

Science Conference Proceedings (OSTI)

The modulation of airsea heat fluxes by geostrophic eddies due to the stirring of temperature at the sea surface is discussed and quantified. It is argued that the damping of eddy temperature variance by such airsea fluxes enhances the ...

Emily Shuckburgh; Guillaume Maze; David Ferreira; John Marshall; Helen Jones; Chris Hill

2011-01-01T23:59:59.000Z

466

The Catalina Eddy Event of July 1987: A Coastally Trapped Mesoscale Response to Synoptic Forcing  

Science Conference Proceedings (OSTI)

The Catalina eddy that existed from 5 July to 12 July 1987 during FIRE (First ISSCP Regional Experiment) over offshore California is analyzed. There were two stages to the eddy's lifecycle. During the first, from 5 July to 1200 UTC 9 July, the ...

John H. E. Clark; Scott R. Dembek

1991-07-01T23:59:59.000Z

467

EIS-0421: Big Eddy-Knight Transmission Line | Department of Energy  

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

21: Big Eddy-Knight Transmission Line 21: Big Eddy-Knight Transmission Line EIS-0421: Big Eddy-Knight Transmission Line Overview BPA is proposing to build a new 500 kilovolt (kV) transmission line in Wasco County, Oregon and Klickitat County, Washington and a new substation in Klickitat County. The new BPA transmission line would extend generally northeast from BPA's existing Big Eddy Substation in The Dalles, Oregon, to a new substation (Knight Substation) proposed to be connected to an existing BPA line about 4 miles northwest of Goldendale, Washington. The proposed Big Eddy Knight Transmission Project is needed to increase transmission capacity to respond to requests for transmission service in this area. Public Comment Opportunities No public comment opportunities available at this time.

468

The Atmospheric Energy Budget and Large-Scale Precipitation Efficiency of Convective Systems during TOGA COARE, GATE, SCSMEX, and ARM: Cloud-Resolving Model Simulations  

Science Conference Proceedings (OSTI)

A two-dimensional version of the Goddard Cumulus Ensemble (GCE) model is used to simulate convective systems that developed in various geographic locations (east Atlantic, west Pacific, South China Sea, and Great Plains in the United States). ...

W-K. Tao; D. Johnson; C-L. Shie; J. Simpson

2004-10-01T23:59:59.000Z

469

The Impact of Large-Scale Forcing on Skill of Simulated Convective Initiation and Upscale Evolution with Convection-Allowing Grid Spacings in the WRF  

Science Conference Proceedings (OSTI)

A set of mesoscale convective systems (MCSs) was simulated using the Weather Research and Forecasting model with 3-km grid spacing to investigate the skill at predicting convective initiation and upscale evolution into an MCS. Precipitation was ...

Jeffrey D. Duda; William A. Gallus Jr.

2013-08-01T23:59:59.000Z

470

Sensitivity of Low-Level Winds Simulated by the WRF Model in Californias Central Valley to Uncertainties in the Large-Scale Forcing and Soil Initialization  

Science Conference Proceedings (OSTI)

The sensitivity of the Weather and Research Forecasting (WRF) model-simulated low-level winds in the Central Valley (CV) of California to uncertainties in the atmospheric forcing and soil initialization is investigated using scatter diagrams for ...

Sara A. Michelson; Jian-Wen Bao

2008-12-01T23:59:59.000Z

471

Can the Increase in the Eddy Length Scale under Global Warming Cause the Poleward Shift of the Jet Streams?  

Science Conference Proceedings (OSTI)

The question of whether an increase in the atmospheric eddy length scale may cause a poleward shift of the midlatitude jet streams is addressed. An increase in the length scale of the eddy reduces its zonal phase speed and so causes eddies to ...

Joseph Kidston; G. K. Vallis; S. M. Dean; J. A. Renwick

2011-07-01T23:59:59.000Z

472

TYPE Ia SUPERNOVAE: CALCULATIONS OF TURBULENT FLAMES USING THE LINEAR EDDY MODEL  

SciTech Connect

The nature of carbon burning flames in Type Ia supernovae is explored as they interact with Kolmogorov turbulence. One-dimensional calculations using the Linear Eddy Model of Kerstein elucidate three regimes of turbulent burning. In the simplest case, large-scale turbulence folds and deforms thin laminar flamelets to produce a flame brush with a total burning rate given approximately by the speed of turbulent fluctuations on the integral scale, U{sub L} , This is the regime where the supernova explosion begins and where most of its pre-detonation burning occurs. As the density declines, turbulence starts to tear the individual flamelets, making broader structures that move faster. For a brief time, these turbulent flamelets are still narrow compared to their spacing and the concept of a flame brush moving with an overall speed of U{sub L} remains valid. However, the typical width of the individual flamelets, which is given by the condition that their turnover time equals their burning time, continues to increase as the density declines. Eventually, mixed regions almost as large as the integral scale itself are transiently formed. At that point, a transition to detonation can occur. The conditions for such a transition are explored numerically and it is estimated that the transition will occur for densities near 1 x 10{sup 7} g cm{sup -3}, provided the turbulent speed on the integral scale exceeds about 20% sonic. An example calculation shows the details of a detonation actually developing.

Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Kerstein, A. R.; Sankaran, V. [Combustion Research Facility, Sandia National Laboratory, Livermore, CA 94551 (United States); Aspden, A. J. [Center for Computational Science and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Roepke, F. K., E-mail: woosley@ucolick.or, E-mail: arkerst@sandia.go, E-mail: AJAspden@lbl.go, E-mail: fritz@mpa-Garching.mpg.d [Max Planck Institut fuer Astrophysik, Garching (Germany)

2009-10-10T23:59:59.000Z

473

Eddy Current Examination of Spent Nuclear Fuel Canister Closure Welds  

SciTech Connect

The National Spent Nuclear Fuel Program (NSNFP) has developed standardized DOE SNF canisters for handling and interim storage of SNF at various DOE sites as well as SNF transport to and SNF handling and disposal at the repository. The final closure weld of the canister will be produced remotely in a hot cell after loading and must meet American Society of Mechanical Engineers (ASME) Section III, Division 3 code requirements thereby requiring volumetric and surface nondestructive evaluation to verify integrity. This paper discusses the use of eddy current testing (ET) to perform surface examination of the completed welds and repair cavities. Descriptions of integrated remote welding/inspection system and how the equipment is intended function will also be discussed.

Arthur D. Watkins; Dennis C. Kunerth; Timothy R. McJunkin

2006-04-01T23:59:59.000Z

474

Surface Characterization of Stainless Steel Part by Eddy Current  

Science Conference Proceedings (OSTI)

The Pacific Northwest National Laboratory (PNNL) has nearly a 40 year history of research and development in the field of nondestructive evaluation (NDE). One area of NDE expertise at PNNL is electromagnetic testing which includes a field of eddy current testing (ET). One benefit is that ET can typically be performed at high speeds, and as a result has found many applications in process monitoring and poduction lines. ET has been used in the nuclear, aerospace, and automotive industries for many years. Et technology lends itself well to the detection of near-surface or surface breaking defects such as surface scratches. This paper provides an overview of theory regarding the usage of ET, selected application studies performed by PNNL, a safety analysis, and a wrtie up pertaining to the operations of ET to detect surface scratches.

Andersen, Eric S.; Hockey, Ronald L.; Prince, James M.; Good, Morris S.

2003-10-01T23:59:59.000Z

475

Some thoughts on an eddy current septum magnet  

SciTech Connect

It is the purpose of this report to describe the thinking and work that went into thoroughly understanding, a specific eddy current septum magnet that will be used in the APS and needs ``fixing.`` The goal is to go beyond mere qualitative understanding and carry the analysis far enough to recognize the real problems of this magnet and to develop the tools to solve them. While it would be very tempting to write this report in very general terms, it would be very difficult to achieve complete generality, and one would risk losing the focus on this specific magnet that needs to have an improved performance. The discussion contains, however, so many generally useful concepts and procedures that it might further be useful for designers of other eddy current septum magnets both at the APS and elsewhere. Since it is necessary not only to have a deep qualitative understanding of several aspects of this type of magnet, but also to quantitatively assess what has to be done to achieve the desired performance, fairly heavy use of mathematical tools was made. In doing so it became clear that the extensive use of these tools is essential not only for this purpose, but also to get the required good qualitative understanding of the device. For instance, it turns out that in this particular instance, an important part of the underlying physics does not become clear until one seems to run into what one might consider, at first, a mathematical problem, whose resolution is not clear until one has found the solution, which then seems ``obvious.`` Even though iron in the septum has a nonlinear relationship between B and H, assuming a constant permeability is sufficient to obtain the information needed to develop a sufficient understanding of the magnet to make some crucial decisions.

Halbach, K. [Argonne National Lab., IL (United States)]|[Lawrence Berkeley Lab., CA (United States)

1995-08-01T23:59:59.000Z

476

Specification of Eddy Transfer Coefficients in Coarse-Resolution Ocean Circulation Models  

Science Conference Proceedings (OSTI)

Parametric representations of oceanic geostrophic eddy transfer of heat and salt are studied ranging fromhorizontal diffusion to the more physically based approaches of Green and Stone (GS) and Gent and McWilliams(GM). The authors argue for a ...

Martin Visbeck; John Marshall; Tom Haine; Mike Spall

1997-03-01T23:59:59.000Z

477

Westinghouse Offers $6,400 in College Scholarships to Eddy County...  

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

Offers 6,400 in College Scholarships to Eddy County Students CARLSBAD, N.M., February 18, 2000 - The Westinghouse Government Services Group today announced that 6,400 in college...

478

Diffusivity, Kinetic Energy Dissipation, and Closure Theories for the Poleward Eddy Heat Flux  

Science Conference Proceedings (OSTI)

Diffusive eddy closure theory for estimating the poleward heat flux is reexamined and tested in the context of a two-layer homogeneous model. Consideration of the inverse energy cascade induced by baroclinic turbulence on the ? plane leads to an ...

G. Lapeyre; I. M. Held

2003-12-01T23:59:59.000Z

479

A Modeling Study of Circulation and Eddies in the Persian Gulf  

Science Conference Proceedings (OSTI)

The circulation and mesoscale eddies in the Persian Gulf are investigated using results from a high-resolution (1 km) Hybrid Coordinate Ocean Model (HYCOM). The circulation in the Persian Gulf is composed of two spatial scales: basin scale and ...

Prasad G. Thoppil; Patrick J. Hogan

2010-09-01T23:59:59.000Z

480

Geostrophic Departure, Local Turning, Speed Change, and Eddy Flux: A New Perspective  

Science Conference Proceedings (OSTI)

Conjunctions of meander passages and cross-stream eddy momentum fluxes are common in western boundary currents. To explore the mechanism linking them, we offer a diagnostic equation of their time-dependent motions. The equation is embodied in the ...

Frank Chew; Mark H. Bushnell

1991-11-01T23:59:59.000Z

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


481

Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain,  

Open Energy Info (EERE)

Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain, Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain, California- Performance Evaluation And Role Of Meteorological Forcing Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Six-Week Time Series Of Eddy Covariance Co2 Flux At Mammoth Mountain, California- Performance Evaluation And Role Of Meteorological Forcing Details Activities (1) Areas (1) Regions (0) Abstract: CO2 and heat fluxes were measured over a six-week period (09/08/2006 to 10/24/2006) by the eddy covariance (EC) technique at the Horseshoe Lake tree kill (HLTK), Mammoth Mountain, CA, a site with complex terrain and high, spatially heterogeneous CO2 emission rates. EC CO2 fluxes ranged from 218 to 3500 g m- 2 d- 1 (mean = 1346 g m- 2 d- 1). Using footprint modeling, EC CO2 fluxes were compared to CO2 fluxes measured by

482

Particle Dispersion and Mixing of Conservative Properties in an Eddy-Resolving Model  

Science Conference Proceedings (OSTI)

We examine the diffusive behavior of the flow field in an eddy-resolving, primitive equation circulation model. Analysis of fluid particle trajectories illustrates the transport mechanisms, which are leading to uniform tracer and potential ...

Claus W. Bning; Michael D. Cox

1988-02-01T23:59:59.000Z

483

Seasonal and Interannual Modulation of the Eddy Kinetic Energy in the Caribbean Sea  

Science Conference Proceedings (OSTI)

Variability of the mesoscale eddy field in the Caribbean Sea is analyzed over the period 19932009 using geostrophic anomalies derived from altimeter data and a high-resolution regional model. The Colombia Basin presents the largest values of ...

Julien Jouanno; Julio Sheinbaum; Bernard Barnier; Jean Marc Molines; Julio Candela

2012-11-01T23:59:59.000Z

484

Eddy Dissipation Rates in Thunderstorms Estimated by Doppler Radar in Relation to Aircraft In Situ Measurements  

Science Conference Proceedings (OSTI)

High-resolution aircraft turbulence measurements, well coordinated with radar Doppler spectral width measurements, have been used to verify radar-estimated energy dissipation rates within thunderstorms anvils. The radar-estimated eddy dissipation ...

Peter Meischner; Robert Baumann; Hartmut Hller; Thomas Jank

2001-10-01T23:59:59.000Z

485

Modeling Studies of Eddies in the Leeuwin Current: The Role of Thermal Forcing  

Science Conference Proceedings (OSTI)

A high resolution, multilevel, primitive equation (PE) model is used to investigate the generation and stability of the Leeuwin Current and eddies off the west coast of Australia. Two numerical experiments are conducted to investigate the roles ...

Mary L. Batteen; Martin J. Rutherford

1990-09-01T23:59:59.000Z

486

Comparison of Eddy Dissipation Rates from Spatial Spectra of Doppler Velocities and Doppler Spectrum Widths  

Science Conference Proceedings (OSTI)

Doppler radars offer unique data from which it is possible to estimate the turbulent eddy dissipation rates, ?. If the inertial subrange extends to lengths longer than the radar resolution volume size, ? can be obtained from the Doppler spectrum ...

Keith A. Brewster; Dusan S. Zrni?

1986-09-01T23:59:59.000Z

487

Feedbacks between Eddy Heat Fluxes and Radiative Heating in an Energy-Balance Model  

Science Conference Proceedings (OSTI)

The response of midlatitude temperature structure to changes in radiative forcing is examined in an analytical energy-balance model that includes parameterized eddy heat fluxes and linear radiative heating. The characteristics of heat-...

Lee E. Branscome; Enda O'Brien

1988-02-01T23:59:59.000Z

488

Surface Eddy Momentum Flux and Velocity Variances in the Southern Ocean from Geosat Altimetry  

Science Conference Proceedings (OSTI)

Satellite altimetry has previously been used to map the magnitude of the surface eddy variability of the global oceans, but the direction of the time-variable velocities have been more difficult to determine. Here, a technique is presented for ...

Rosemary Morrow; Richard Coleman; John Church; Dudley Chelton

1994-10-01T23:59:59.000Z

489

An Eddy-Resolving Numerical Model of the Ventilated Thermocline: Time Dependence  

Science Conference Proceedings (OSTI)

A primitive equation, eddy-resolving numerical model is used to study the inherent time scales of variability in the subtropical ocean, assuming temporally constant surface forcing. Three primary scales arise: mesoscale variability of roughly 50-...

Michael D. Cox

1987-07-01T23:59:59.000Z

490

Adjoint-Based Estimation of Eddy-Induced Tracer Mixing Parameters in the Global Ocean  

Science Conference Proceedings (OSTI)

Using the German Estimating the Circulation and Climate of the Ocean (GECCO) synthesis framework, four separate eddy tracer mixing coefficients are adjusted jointly with external forcing fields, such as to reduce a global misfit between the model ...

Chuanyu Liu; Armin Khl; Detlef Stammer

2012-07-01T23:59:59.000Z

491

The Influence of Eddies on Tracer Transport in the Abyssal Ocean  

Science Conference Proceedings (OSTI)

Tracer transport mechanisms in a deep western boundary current (DWBC) are explored using a three-layer, eddy-resolving quasigeostrophic model. The model is forced with a steady, sinusoidal wind stress. The effects of the wind stress, coupled with ...

Carol Ladd; Lu Anne Thompson

1998-09-01T23:59:59.000Z

492

The Nondeterministic Nature of Kuroshio Penetration and Eddy Shedding in the South China Sea  

Science Conference Proceedings (OSTI)

A ?, 6-layer Pacific version of the Naval Research Laboratory Layered Ocean Model is used to investigate the nondeterministic nature of Kuroshio intrusion and eddy shedding into the South China Sea (SCS) on annual and interannual timescales. ...

E. Joseph Metzger; Harley E. Hurlburt

2001-07-01T23:59:59.000Z

493

Tower and Aircraft Eddy Covariance Measurements of Water Vapor, Energy, and Carbon Dioxide Fluxes during SMACEX  

Science Conference Proceedings (OSTI)

A network of eddy covariance (EC) and micrometeorological flux (METFLUX) stations over corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] canopies was established as part of the Soil MoistureAtmosphere Coupling Experiment (SMACEX) in ...

J. H. Prueger; J. L. Hatfield; T. B. Parkin; W. P. Kustas; L. E. Hipps; C. M. U. Neale; J. I. MacPherson; W. E. Eichinger; D. I. Cooper

2005-12-01T23:59:59.000Z

494

A Numerical Study of Loop Current Eddy Interaction with Topography in the Western Gulf of Mexico  

Science Conference Proceedings (OSTI)

Anticyclones originating from the Loop Current are known to propagate into the western Gulf of Mexico. Their frequency of generation, their long lifetimes, and satellite data suggest that at any one time one or more eddies may occupy the Gulf. ...

David C. Smith IV

1986-07-01T23:59:59.000Z

495

Empirical Models of the Eddy Heat Flux and Vertical Shear on Short Time Scales  

Science Conference Proceedings (OSTI)

The relationship between the eddy heat flux and vertical shear in the extratropical atmosphere is studied by developing various linear stochastic models fitted to the observed January and July Northern Hemispheric data. Models are univariate or ...

Steven J. Ghan

1984-02-01T23:59:59.000Z

496

Understanding the Regional Variability of Eddy Diffusivity in the Pacific Sector of the Southern Ocean  

E-Print Network (OSTI)

A diagnostic framework is presented, based on the Nakamura effective diffusivity, to investigate the regional variation in eddy diffusivity. Comparison of three different diffusivity calculations enables the effects of ...

Shuckburgh, Emily

497

Subgrid-Scale Eddy Parameterization by Statistical Mechanics in a Barotropic Ocean Model  

Science Conference Proceedings (OSTI)

The feasibility of using a subgrid-scale eddy parameterization, based on statistical mechanics of potential vorticity, is investigated. A specific implementation is derived for the somewhat classic barotropic vorticity equation in the case of a ...

Evguni Kazantsev; Jol Sommeria; Jacques Verron

1998-06-01T23:59:59.000Z

498

Eddy Advective and Diffusive Transports of Heat and Salt in the Southern Ocean  

Science Conference Proceedings (OSTI)

There are two distinct mechanisms by which eddies provide systematic transport of tracer on isopycnals: the advective transport, associated with the slumping of isopycnals, and the diffusive transport, associated with down-gradient diffusion. ...

Mei-Man Lee; A. J. George Nurser; A. C. Coward; B. A. de Cuevas

2007-05-01T23:59:59.000Z

499

Importance of Low-Frequency Contributions to Eddy Fluxes Observed over Rough Surfaces  

Science Conference Proceedings (OSTI)

Eddy covariance flux observations at a deciduous temperate forest site (83 days) and at a boreal forest site (21 days) are analyzed for midday periods (11001400 LT). Approximate stationarity of the time series is demonstrated, and the ensemble-...

Ricardo K. Sakai; David R. Fitzjarrald; Kathleen E. Moore

2001-12-01T23:59:59.000Z

500

Subthermocline Eddies over the Washington Continental Slope as Observed by Seagliders, 2003-09  

Science Conference Proceedings (OSTI)

In the California Current System, subthermocline, lens-like anticyclonic eddies generated within the California Undercurrent (CU) are one mechanism for lateral transport of the warm, saline waters of the CU. Garfield et al. (1999) established the ...

Noel A. Pelland; Charles C. Eriksen; Craig M. Lee