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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

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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...

20

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

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

22

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

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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

39

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

40

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

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

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

42

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

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

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

55

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

56

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

57

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

58

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

59

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

60

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

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

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

62

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

63

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

64

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

65

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

66

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

67

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

68

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

69

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

70

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

71

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

72

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

73

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

74

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

75

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

76

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

77

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

78

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

79

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

80

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

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

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

82

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

83

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

84

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

85

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

86

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

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 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

88

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

89

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

90

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

91

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

92

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

93

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.

94

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

95

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

96

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

97

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

98

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

99

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

100

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

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

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

102

DNS and LES of decaying isotropic turbulence with and without frame rotation using lattice Boltzmann method  

Science Conference Proceedings (OSTI)

The objective of the paper is to assess the effectiveness of the lattice Boltzmann equation (LBE) as a computational tool for performing direct numerical simulations (DNS) and large-eddy simulations (LES) of turbulent flows. Decaying homogeneous isotropic ... Keywords: Smagorinsky model, decaying homogeneous isotropic turbulence in 3D, direct numerical simulation, large-eddy simulation, lattice Boltzmann equation

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

2005-11-01T23:59:59.000Z

103

Quality Issues in Combustion LES  

Science Conference Proceedings (OSTI)

Combustion LES requires modelling of physics beyond the flow-field only. These additional models lead to further quality issues and an even stronger need to quantify simulation and modelling errors. We illustrate stability problems, the need for consistent ... Keywords: Combustion, Error landscape, LES, Large-Eddy simulation, Quality, Turbulence

A. M. Kempf; B. J. Geurts; T. Ma; M. W. Pettit; O. T. Stein

2011-10-01T23:59:59.000Z

104

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

105

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

106

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

107

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

108

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

109

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

110

An adaptive implicit-explicit scheme for the DNS and LES of compressible flows on unstructured grids  

Science Conference Proceedings (OSTI)

An adaptive implicit-explicit scheme for Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES) of compressible turbulent flows on unstructured grids is developed. The method uses a node-based finite-volume discretization with Summation-by-Parts ... Keywords: Compressible flows, DNS, IMEX, LES, SAT, SBP, Time-advancement scheme, Unstructured grids

Mohammad Shoeybi; Magnus Svrd; Frank E. Ham; Parviz Moin

2010-08-01T23:59:59.000Z

111

A new approach to sub-grid surface tension for LES of two-phase flows  

Science Conference Proceedings (OSTI)

In two-phase flow, the presence of inter-phasal surface - the interface - causes additional terms to appear in LES formulation. Those terms were ignored in contemporary works, for the lack of model and because the authors expected them to be of negligible ... Keywords: CLSVOF, Large Eddy Simulation, Surface tension, Two-phase flow

W. Aniszewski; A. Bogus?Awski; M. Marek; A. Tyliszczak

2012-08-01T23:59:59.000Z

112

Molecular diffusion effects in LES of a piloted methaneair flame Konstantin A. Kemenov  

E-Print Network (OSTI)

Molecular diffusion effects in LES of a piloted methane­air flame Konstantin A. Kemenov , Stephen-premixed turbulent combustion Large-eddy simulation Molecular diffusion Sandia flame D a b s t r a c t Molecular splines relationships are employed to represent thermochemical variables. The role of molecular

Pope, Stephen B.

113

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

114

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

115

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

116

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...

117

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

118

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,...

119

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

120

Simulating atmosphere flow for wind energy applications with WRF-LES  

SciTech Connect

Forecasts of available wind energy resources at high spatial resolution enable users to site wind turbines in optimal locations, to forecast available resources for integration into power grids, to schedule maintenance on wind energy facilities, and to define design criteria for next-generation turbines. This array of research needs implies that an appropriate forecasting tool must be able to account for mesoscale processes like frontal passages, surface-atmosphere interactions inducing local-scale circulations, and the microscale effects of atmospheric stability such as breaking Kelvin-Helmholtz billows. This range of scales and processes demands a mesoscale model with large-eddy simulation (LES) capabilities which can also account for varying atmospheric stability. Numerical weather prediction models, such as the Weather and Research Forecasting model (WRF), excel at predicting synoptic and mesoscale phenomena. With grid spacings of less than 1 km (as is often required for wind energy applications), however, the limits of WRF's subfilter scale (SFS) turbulence parameterizations are exposed, and fundamental problems arise, associated with modeling the scales of motion between those which LES can represent and those for which large-scale PBL parameterizations apply. To address these issues, we have implemented significant modifications to the ARW core of the Weather Research and Forecasting model, including the Nonlinear Backscatter model with Anisotropy (NBA) SFS 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 are also modifying WRF's terrain-following coordinate system by implementing an immersed boundary method (IBM) approach to account for the effects of complex terrain. Companion papers presenting idealized simulations with NBA-RSFS-WRF (Mirocha et al.) and IBM-WRF (K. A. Lundquist et al.) are also presented. Observations of flow through the Altamont Pass (Northern California) wind farm are available for validation of the WRF modeling tool for wind energy applications. In this presentation, we use these data to evaluate simulations using the NBA-RSFS-WRF tool in multiple configurations. We vary nesting capabilities, multiple levels of RSFS reconstruction, SFS turbulence models (the new NBA turbulence model versus existing WRF SFS turbulence models) to illustrate the capabilities of the modeling tool and to prioritize recommendations for operational uses. Nested simulations which capture both significant mesoscale processes as well as local-scale stable boundary layer effects are required to effectively predict available wind resources at turbine height.

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

2008-01-14T23:59:59.000Z

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

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

122

On integrating LES and laboratory turbulent flow experiments  

SciTech Connect

Critical issues involved in large eddy simulation (LES) experiments relate to the treatment of unresolved subgrid scale flow features and required initial and boundary condition supergrid scale modelling. The inherently intrusive nature of both LES and laboratory experiments is noted in this context. Flow characterization issues becomes very challenging ones in validation and computational laboratory studies, where potential sources of discrepancies between predictions and measurements need to be clearly evaluated and controlled. A special focus of the discussion is devoted to turbulent initial condition issues.

Grinstein, Fernando Franklin [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

123

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

124

A LES-Langevin model for turbulence  

E-Print Network (OSTI)

We propose a new model of turbulence for use in large-eddy simulations (LES). The turbulent force, represented here by the turbulent Lamb vector, is divided in two contributions. The contribution including only subfilter fields is deterministically modeled through a classical eddy-viscosity. The other contribution including both filtered and subfilter scales is dynamically computed as solution of a generalized (stochastic) Langevin equation. This equation is derived using Rapid Distortion Theory (RDT) applied to the subfilter scales. The general friction operator therefore includes both advection and stretching by the resolved scale. The stochastic noise is derived as the sum of a contribution from the energy cascade and a contribution from the pressure. The LES model is thus made of an equation for the resolved scale, including the turbulent force, and a generalized Langevin equation integrated on a twice-finer grid. The model is validated by comparison to DNS and is tested against classical LES models for i...

Laval, J P; Dubrulle, Berengere; Laval, Jean-Philippe

2006-01-01T23:59:59.000Z

125

Microsoft Word - 40975_CFDR_LES Software_Factsheet_Rev01_00-00-03.doc  

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

LES Software for the Design of Low Emission Combustion Systems for Vision 21 Plants I. Project Participants CFD Research Corporation (Prime) Siemens-Westinghouse Georgia Institute of Technology Pratt&Whitney University of California, Berkeley Woodward FST Virginia Tech Parker Hannifin Rolls-Royce GE Power Systems Solar Turbines John Zink Company Coen Company Vapor Power McDermott Technologies RamGen Power Air Force Research Laboratory NASA Glenn Research II. Project Description Objectives: In this three-year project, an advanced computational software tool based on Large Eddy Simulation (LES) methods is being developed for the design of low emission combustion systems required for Vision 21 clean energy plants.

126

Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.  

DOE Green Energy (OSTI)

Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E (Energy Systems); (Univ. of Connecticut); (CONVERGENT Science)

2012-01-01T23:59:59.000Z

127

Adaptive LES Methodology for Turbulent Flow Simulations  

Science Conference Proceedings (OSTI)

Although turbulent flows are common in the world around us, a solution to the fundamental equations that govern turbulence still eludes the scientific community. Turbulence has often been called one of the last unsolved problem in classical physics, yet it is clear that the need to accurately predict the effect of turbulent flows impacts virtually every field of science and engineering. As an example, a critical step in making modern computational tools useful in designing aircraft is to be able to accurately predict the lift, drag, and other aerodynamic characteristics in numerical simulations in a reasonable amount of time. Simulations that take months to years to complete are much less useful to the design cycle. Much work has been done toward this goal (Lee-Rausch et al. 2003, Jameson 2003) and as cost effective accurate tools for simulating turbulent flows evolve, we will all benefit from new scientific and engineering breakthroughs. The problem of simulating high Reynolds number (Re) turbulent flows of engineering and scientific interest would have been solved with the advent of Direct Numerical Simulation (DNS) techniques if unlimited computing power, memory, and time could be applied to each particular problem. Yet, given the current and near future computational resources that exist and a reasonable limit on the amount of time an engineer or scientist can wait for a result, the DNS technique will not be useful for more than 'unit' problems for the foreseeable future (Moin & Kim 1997, Jimenez & Moin 1991). The high computational cost for the DNS of three dimensional turbulent flows results from the fact that they have eddies of significant energy in a range of scales from the characteristic length scale of the flow all the way down to the Kolmogorov length scale. The actual cost of doing a three dimensional DNS scales as Re{sup 9/4} due to the large disparity in scales that need to be fully resolved. State-of-the-art DNS calculations of isotropic turbulence have recently been completed at the Japanese Earth Simulator (Yokokawa et al. 2002, Kaneda et al. 2003) using a resolution of 40963 (approximately 10{sup 11}) grid points with a Taylor-scale Reynolds number of 1217 (Re {approx} 10{sup 6}). Impressive as these calculations are, performed on one of the world's fastest super computers, more brute computational power would be needed to simulate the flow over the fuselage of a commercial aircraft at cruising speed. Such a calculation would require on the order of 10{sup 16} grid points and would have a Reynolds number in the range of 108. Such a calculation would take several thousand years to simulate one minute of flight time on today's fastest super computers (Moin & Kim 1997). Even using state-of-the-art zonal approaches, which allow DNS calculations that resolve the necessary range of scales within predefined 'zones' in the flow domain, this calculation would take far too long for the result to be of engineering interest when it is finally obtained. Since computing power, memory, and time are all scarce resources, the problem of simulating turbulent flows has become one of how to abstract or simplify the complexity of the physics represented in the full Navier-Stokes (NS) equations in such a way that the 'important' physics of the problem is captured at a lower cost. To do this, a portion of the modes of the turbulent flow field needs to be approximated by a low order model that is cheaper than the full NS calculation. This model can then be used along with a numerical simulation of the 'important' modes of the problem that cannot be well represented by the model. The decision of what part of the physics to model and what kind of model to use has to be based on what physical properties are considered 'important' for the problem. It should be noted that 'nothing is free', so any use of a low order model will by definition lose some information about the original flow.

Oleg V. Vasilyev

2008-06-12T23:59:59.000Z

128

Modlisation et simulation numrique du colmatage lchelle du sous-canal dans les gnrateurs de vapeur.  

E-Print Network (OSTI)

??Ce travail de thse s'inscrit dans le cadre d'un projet de recherche industriel visant amliorer les mthodes et les outils de simulation du comportement (more)

Prusek, Thomas

2012-01-01T23:59:59.000Z

129

Marine low cloud sensitivity to an idealized climate change: The CGILS LES intercomparison  

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

low low cloud sensitivity to an idealized climate change: The CGILS LES intercomparison Peter N. Blossey, 1 Christopher S. Bretherton, 1 Minghua Zhang, 2 Anning Cheng, 3 Satoshi Endo, 4 Thijs Heus, 5 Yangang Liu, 4 Adrian P. Lock, 6 Stephan R. de Roode, 7 and Kuan-Man Xu 8 Received 31 July 2012; revised 4 February 2013; accepted 20 February 2013. [1] Subtropical marine low cloud sensitivity to an idealized climate change is com- pared in six large-eddy simulation (LES) models as part of CGILS. July cloud cover is simulated at three locations over the subtropical northeast Pacific Ocean, which are typified by cold sea surface temperatures (SSTs) under well-mixed stratocumulus, cool SSTs under decoupled stratocumulus, and shallow cumulus clouds overlying warmer SSTs. The idealized climate change includes a uniform 2 K SST increase with corre- sponding moist-adiabatic warming aloft and

130

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

131

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...

132

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

133

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

134

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

135

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

136

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

137

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

138

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

139

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

140

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

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

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

SciTech Connect

Application and testing of the new combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this 10th quarterly report. CFD Research Corporation has developed the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. In this quarter, validation and testing of the combustion LES code was performed for the DOE-Simval combustor. Also, Beta testing by consortium members was performed for various burner and combustor configurations. In the two quarters ahead, CFDRC will validate the code on the new DOE SimVal experiments. Experimental data from DOE should be available in June 2003, though LES calculations are currently being performed. This will ensure a truly predictive test of the software. CFDRC will also provide help to the consortium members on running their cases, and incorporate improvements to the software suggested by the beta testers. The beta testers will compare their predictions with experimental measurements and other numerical calculations. At the end of this project (October, 2003), a final released version of the software will be available for licensing to the general public.

Steven Cannon; Clifford Smith

2003-04-01T23:59:59.000Z

142

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

143

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

144

Mean and Flux Horizontal Variability of Virtual Potential Temperature, Moisture, and Carbon Dioxide: Aircraft Observations and LES Study  

Science Conference Proceedings (OSTI)

The effects of the horizontal variability of surface properties on the turbulent fluxes of virtual potential temperature, moisture, and carbon dioxide are investigated by combining aircraft observations with large-eddy simulations (LESs). Daytime ...

Monica Grska; Jordi Vil-Guerau de Arellano; Margaret A. LeMone; Chiel C. van Heerwaarden

2008-11-01T23:59:59.000Z

145

An LES Study of the Impacts of Land Surface Heterogeneity on Dispersion in the Convective Boundary Layer  

Science Conference Proceedings (OSTI)

A systematic analysis of the impacts of heat patches and topographical features on the dispersion of passive materials in a shear-free convective boundary layer (CBL) was performed. Large eddy simulations and a Lagrangian particle dispersion ...

S. G. Gopalakrishnan; Roni Avissar

2000-01-01T23:59:59.000Z

146

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

147

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

DOE Green Energy (OSTI)

Further development of a combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this sixth quarterly report. CFD Research Corporation (CFDRC) is developing the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. In this quarter, in-situ adaptive tabulation (ISAT) for efficient chemical rate storage and retrieval was implemented and tested within the Linear Eddy Model (LEM). ISAT type 3 is being tested so that extrapolation can be performed and further improve the retrieval rate. Further testing of the LEM for subgrid chemistry was performed for parallel applications and for multi-step chemistry. Validation of the software on backstep and bluff-body reacting cases were performed. Initial calculations of the SimVal experiment at Georgia Tech using their LES code were performed. Georgia Tech continues the effort to parameterize the LEM over composition space so that a neural net can be used efficiently in the combustion LES code. A new and improved Artificial Neural Network (ANN), with log-transformed output, for the 1-step chemistry was implemented in CFDRC's LES code and gave reasonable results. This quarter, the 2nd consortium meeting was held at CFDRC. Next quarter, LES software development and testing will continue. Alpha testing of the code will continue to be performed on cases of interest to the industrial consortium. Optimization of subgrid models will be pursued, particularly with the ISAT approach. Also next quarter, the demonstration of the neural net approach, for multi-step chemical kinetics speed-up in CFD-ACE+, will be accomplished.

Steven Cannon; Baifang Zuo; Virgil Adumitroaie; Keith McDaniel; Clifford Smith

2002-04-30T23:59:59.000Z

148

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

149

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

150

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

151

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

152

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

153

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...

154

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

Science Conference Proceedings (OSTI)

Vision 21 combustion systems will require innovative low emission designs and low development costs if Vision 21 goals are to be realized. In this three-year project, an advanced computational software tool will be developed for the design of low emission combustion systems required for Vision 21 clean energy plants. The combustion Large Eddy Simulation (LES) software will be able to accurately simulate the highly transient nature of gaseous-fueled turbulent combustion so that innovative concepts can be assessed and developed with fewer high-cost experimental tests. During the first year, the project included the development and implementation of improved chemistry (reduced GRI mechanism), subgrid turbulence (localized dynamic), and subgrid combustion-turbulence interaction (Linear Eddy) models into the CFDACE+ code. University expertise (Georgia Tech and UC Berkeley) was utilized to help develop and implement these advanced submodels into the unstructured, parallel CFD flow solver, CFD-ACE+. Efficient numerical algorithms that rely on in situ look-up tables or artificial neural networks were implemented for chemistry calculations. In the second year, the combustion LES software was evaluated and validated using experimental data from lab-scale and industrial test configurations. This code testing (i.e., alpha testing) was performed by CFD Research Corporation's engineers. During the third year, six industrial and academic partners used the combustion LES code and exercised it on problems of their choice (i.e., beta testing). Final feedback and optimizations were then be implemented in the final release version of the combustion LES software that will be licensed to the general public. An additional one-year task was added for the fourth year of this program entitled, ''LES Simulations of SIMVAL Results''. For this task, CFDRC performed LES calculations of selected SIMVAL cases, and compared predictions with measurements. In addition to comparisons with NO{sub x} and CO exit measurements, comparisons were made to measured pressure oscillations. Possible gaps in the data sets were identified, as well as potential areas of improvement for combustion and turbulence models. Work in this seventeenth quarter (October-December 2004) consisted of writing the draft final report for review by DOE. The report was delivered to DOE in January, 2005.

Clifford E. Smith

2005-04-01T23:59:59.000Z

155

Argonne Leadership Computing Facility Argonne National Laboratory  

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

million hours to use Large Eddy Simulation (LES) as an acoustic diagnostic and design tool to spur innovation in next-generation quieter aircraft engines and wind turbines,...

156

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

157

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

158

Lattice Boltzmann equation simulations of turbulence, mixing, and combustion  

E-Print Network (OSTI)

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

Yu, Huidan

2004-12-01T23:59:59.000Z

159

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

DOE Green Energy (OSTI)

In this project, an advanced computational software tool was developed for the design of low emission combustion systems required for Vision 21 clean energy plants. Vision 21 combustion systems, such as combustors for gas turbines, combustors for indirect fired cycles, furnaces and sequestrian-ready combustion systems, will require innovative low emission designs and low development costs if Vision 21 goals are to be realized. The simulation tool will greatly reduce the number of experimental tests; this is especially desirable for gas turbine combustor design since the cost of the high pressure testing is extremely costly. In addition, the software will stimulate new ideas, will provide the capability of assessing and adapting low-emission combustors to alternate fuels, and will greatly reduce the development time cycle of combustion systems. The revolutionary combustion simulation software is able to accurately simulate the highly transient nature of gaseous-fueled (e.g. natural gas, low BTU syngas, hydrogen, biogas etc.) turbulent combustion and assess innovative concepts needed for Vision 21 plants. In addition, the software is capable of analyzing liquid-fueled combustion systems since that capability was developed under a concurrent Air Force Small Business Innovative Research (SBIR) program. The complex physics of the reacting flow field are captured using 3D Large Eddy Simulation (LES) methods, in which large scale transient motion is resolved by time-accurate numerics, while the small scale motion is modeled using advanced subgrid turbulence and chemistry closures. In this way, LES combustion simulations can model many physical aspects that, until now, were impossible to predict with 3D steady-state Reynolds Averaged Navier-Stokes (RANS) analysis, i.e. very low NOx emissions, combustion instability (coupling of unsteady heat and acoustics), lean blowout, flashback, autoignition, etc. LES methods are becoming more and more practical by linking together tens to hundreds of PCs and performing parallel computations with fine grids (millions of cells). Such simulations, performed in a few weeks or less, provide a very cost-effective complement to experimental testing. In 5 years, these same calculations can be performed in 24 hours or less due to the expected increase of computing power and improved numerical techniques. This project was a four-year program. During the first year, the project included the development and implementation of improved chemistry (reduced GRI mechanism), subgrid turbulence (localized dynamic), and subgrid combustion-turbulence interaction (Linear Eddy) models into the CFD-ACE+ code. University expertise (Georgia Tech and University of California, Berkeley) was utilized to help develop and implement these advanced submodels into the unstructured, parallel CFD flow solver, CFD-ACE+. Efficient numerical algorithms that rely on in situ look-up tables or artificial neural networks were implemented for chemistry calculations. In the second year, the combustion LES software was evaluated and validated using experimental data from lab-scale and industrial test configurations. This code testing (i.e., alpha testing) was performed by CFD Research Corporation's engineers. During the third year, six industrial and academic partners used the combustion LES code and exercised it on problems of their choice (i.e., beta testing). Final feedback and optimizations were then implemented into the final release (licensed) version of the combustion LES software to the general public. An additional one-year task was added for the fourth year of this program entitled, ''LES Simulations of SIMVAL Results''. For this task, CFDRC performed LES calculations of selected DoE SIMVAL cases, and compared predictions with measurements from NETL. In addition to comparisons with NOx and CO exit measurements, comparisons were made to measured pressure oscillations. Potential areas of improvement for combustion and turbulence models were identified. In conclusion, this program advanced the state-of-the-art in combustion LES an

Clifford E. Smith; Steven M. Cannon; Virgil Adumitroaie; David L. Black; Karl V. Meredith

2005-01-01T23:59:59.000Z

160

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

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161

Examination of the Mixed Layer Deepening Process during Convection Using LES  

Science Conference Proceedings (OSTI)

Analysis of large-eddy simulation data of the ocean mixed layer under convection reveals that the contribution from wind stress decreases with time as a result of inertial oscillation in the extratropical ocean and that it leads to a rapid ...

Yign Noh; Gahyun Goh; Siegfried Raasch

2010-09-01T23:59:59.000Z

162

Comprehensive Approaches to Multiphase Flows in Geophysics - Application to nonisothermal, nonhomogenous, unsteady, large-scale, turbulent dusty clouds I. Hydrodynamic and Thermodynamic RANS and LES Models  

Science Conference Proceedings (OSTI)

The objective of this manuscript is to fully derive a geophysical multiphase model able to ''accommodate'' different multiphase turbulence approaches; viz., the Reynolds Averaged Navier-Stokes (RANS), the Large Eddy Simulation (LES), or hybrid RANSLES. This manuscript is the first part of a larger geophysical multiphase project--lead by LANL--that aims to develop comprehensive modeling tools for large-scale, atmospheric, transient-buoyancy dusty jets and plume (e.g., plinian clouds, nuclear ''mushrooms'', ''supercell'' forest fire plumes) and for boundary-dominated geophysical multiphase gravity currents (e.g., dusty surges, diluted pyroclastic flows, dusty gravity currents in street canyons). LES is a partially deterministic approach constructed on either a spatial- or a temporal-separation between the large and small scales of the flow, whereas RANS is an entirely probabilistic approach constructed on a statistical separation between an ensemble-averaged mean and higher-order statistical moments (the so-called ''fluctuating parts''). Within this specific multiphase context, both turbulence approaches are built up upon the same phasic binary-valued ''function of presence''. This function of presence formally describes the occurrence--or not--of any phase at a given position and time and, therefore, allows to derive the same basic multiphase Navier-Stokes model for either the RANS or the LES frameworks. The only differences between these turbulence frameworks are the closures for the various ''turbulence'' terms involving the unknown variables from the fluctuating (RANS) or from the subgrid (LES) parts. Even though the hydrodynamic and thermodynamic models for RANS and LES have the same set of Partial Differential Equations, the physical interpretations of these PDEs cannot be the same, i.e., RANS models an averaged field, while LES simulates a filtered field. In this manuscript, we also demonstrate that this multiphase model fully fulfills the second law of thermodynamics and fulfills the necessary requirements for a well-posed initial-value problem. In the next manuscripts, we will further develop specific closures for multiphase RANS, LES, and hybrid-LES.

S. Dartevelle

2005-09-05T23:59:59.000Z

163

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

164

Numerical simulation of unsteady flow in centrifugal pump impeller at off-design condition by hybrid RANS/LES approaches  

Science Conference Proceedings (OSTI)

A new kind of hybrid RANS/LES turbulence modeling method - SST based SAS model is first time used for studying the stall phenomena in a centrifugal pump impeller at off-design condition in present paper. The previous reported two channel ... Keywords: centrifugal impeller, flow visualization, hybrid RANS/LES, off-design condition

Wei Zhang; Yunchao Yu; Hongxun Chen

2009-08-01T23:59:59.000Z

165

Three dimensional simulations of Richtmyer-Meshkov instabilities in gas-curtain shock-tube experiments  

Science Conference Proceedings (OSTI)

It is not feasible to compute high Reynolds-number (Re) turbulent flows by directly resolving all scales of motion and material interfaces; instead, macroscale portions of the unsteady turbulent motion are computed while the rest of the flow physics including molecular diffusion and other micro scale physics (e.g., combustion) remains unresolved. In large eddy simulation (LES), the large energy containing structures are resolved whereas the smaller, presumably more isotropic, structures are filtered out and their unresolved subgrid scale (SGS) effects are modeled. The construction of SGS models for LES is pragmatic and based primarily on empirical information. Adding to the physics based difficulties in developing and validating SGS models, truncation terms due to discretization are comparable to SGS models in typical LES strategies, and LES resolution requirements become prohibitively expensive for practical flows and regimes. Implicit LES (ILES) - and monotone integrated LES (MILES) introduced earlier, effectively address the seemingly insurmountable issues posed to LES by underresolution, by relying on the use of SGS modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive unresolved simulations of turbulent velocity fields are possible using any of the class of nonoscillatory finite-volume (NFV) numerical algorithms. Popular NFV methods such as flux-corrected transport (FCT), the piecewise parabolic method (PPM), total variation diminishing (TVD), and hybrid algorithms are being used for ILES. In many applications of interest, turbulence is generated by shock waves via Richtmyer-Meshkov instabilities (RMI). The instability results in vorticity being introduced at material interfaces by the impulsive loading of the shock wave. A critical feature of this impulsive driving is that the turbulence decays as dissipation removes kinetic energy from the system. RMI add the complexity of shock waves and other compressible effects to the basic physics associated with mixing; compressibility further affects the basic nature of material mixing when mass density and material mixing fluctuation effects are not negligible. Because RMI are shock-driven, resolution requirements make direct numerical simulation impossible even on the largest supercomputers. State-of-the-art simulations of RMI instabilities use hybrid methods which require switching between the use of shock capturing schemes and conventional (explicit) LES depending on the local flow conditions. On the other hand. because ILES is based on (locally adaptive) NFV methods it is naturally capable of emulating shock physics. The unique combination of shock and turbulence emulation capabilities supports direct use of ILES as an effective simulation anzatz in RMI research. This possibility is explored in the current paper in the context of a prototypical case study for which the available laboratory data can be used to test and validate ILES modeling based on various NFV methods.

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

2009-01-01T23:59:59.000Z

166

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

167

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

168

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

169

Enabling Advanced Modeling and Simulations for Fuel-Flexible Combustors  

Science Conference Proceedings (OSTI)

The overall goal of the present project is to enable advanced modeling and simulations for the design and optimization of fuel-flexible turbine combustors. For this purpose we use a high-fidelity, extensively-tested large-eddy simulation (LES) code and state-of-the-art models for premixed/partially-premixed turbulent combustion developed in the PI's group. In the frame of the present project, these techniques are applied, assessed, and improved for hydrogen enriched premixed and partially premixed gas-turbine combustion. Our innovative approaches include a completely consistent description of flame propagation, a coupled progress variable/level set method to resolve the detailed flame structure, and incorporation of thermal-diffusion (non-unity Lewis number) effects. In addition, we have developed a general flamelet-type transformation holding in the limits of both non-premixed and premixed burning. As a result, a model for partially premixed combustion has been derived. The coupled progress variable/level method and the general flamelet tranformation were validated by LES of a lean-premixed low-swirl burner that has been studied experimentally at Lawrence Berkeley National Laboratory. The model is extended to include the non-unity Lewis number effects, which play a critical role in fuel-flexible combustor with high hydrogen content fuel. More specifically, a two-scalar model for lean hydrogen and hydrogen-enriched combustion is developed and validated against experimental and direct numerical simulation (DNS) data. Results are presented to emphasize the importance of non-unity Lewis number effects in the lean-premixed low-swirl burner of interest in this project. The proposed model gives improved results, which shows that the inclusion of the non-unity Lewis number effects is essential for accurate prediction of the lean-premixed low-swirl flame.

Heinz Pitsch

2010-05-31T23:59:59.000Z

170

Prediction of extinction and reignition in nonpremixed turbulent flames using a flamelet/progress variable model. 2. Application in LES of Sandia flames D and E  

SciTech Connect

An extension of the flamelet/progress variable (FPV) model for the prediction of extinction and reignition is applied in large-eddy simulation (LES) of flames D and E of the Sandia piloted turbulent jet flame series. This model employs a presumed probability density function (PDF), in which the marginal PDF of a reactive scalar is modeled by a statistically most likely distribution. This provides two advantages. First of all, the shape of the distribution depends on chemical and mixing time-scale information, and second, an arbitrary number of moments can be enforced. This model was analyzed in an a priori study in the first part of this work. In the present LES application, the first two moments of mixture fraction and reaction progress variable are used to constrain the shape of the presumed PDF. Transport equations for these quantities are solved, and models for the residual scalar dissipation rates, which appear as unclosed terms in the equations for the scalar variances, are provided. Statistical flow field quantities for axial velocity, mixture fraction, and temperature, obtained from the extended FPV model, are in good agreement with experimental data. Mixture-fraction-conditioned data, conditional PDFs, and burning indices are computed and compared with the delta-function flamelet closure model, which employs a Dirac distribution as a model for the marginal PDF of the reaction progress parameter. The latter model considerably underpredicts the amount of local extinction, which shows that the consideration of second-moment information in the presumed PDF of the reaction progress parameter is important for the accurate prediction of extinction and reignition. Mixture-fraction-conditioned results obtained from the extended FPV model are in good agreement with experimental data; however, the overprediction of the consumption of fuel and oxidizer on the fuel-rich side results in an overprediction of minor species. The predictions for the conditional PDFs and burning indices are in good agreement with measurements. (author)

Ihme, Matthias; Pitsch, Heinz [Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States)

2008-10-15T23:59:59.000Z

171

Turbulence Anisotropy Carried by Streaks in the Neutral Atmospheric Surface Layer  

Science Conference Proceedings (OSTI)

The authors investigate the relationships between coherent structures and turbulence anisotropy in the neutral planetary boundary layer by means of empirical orthogonal function (EOF) analysis of large-eddy simulation (LES) data. The simulated ...

Thomas Dubos; Philippe Drobinski; Pierre Carlotti

2008-08-01T23:59:59.000Z

172

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

173

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

174

Fully Lagrangian Floats in Labrador Sea Deep Convection: Comparison of Numerical and Experimental Results  

Science Conference Proceedings (OSTI)

Measurements of deep convection from fully Lagrangian floats deployed in the Labrador Sea during February and March 1997 are compared with results from model drifters embedded in a large eddy simulation (LES) of the rapidly deepening mixed layer. ...

Ramsey R. Harcourt; Elizabeth L. Steffen; Roland W. Garwood; Eric A. D'Asaro

2002-02-01T23:59:59.000Z

175

On the Parameterization of Surface Roughness at Regional Scales  

Science Conference Proceedings (OSTI)

A parameterization for surface roughness and blending height at regional scales, under neutral atmospheric stability, is studied and tested. The analysis is based on a suite of large-eddy simulations (LES) over surfaces with varying roughness ...

Elie Bou-Zeid; Marc B. Parlange; Charles Meneveau

2007-01-01T23:59:59.000Z

176

Numerical and Laboratory Study of a Horizontally Evolving Convective Boundary Layer. Part I: Transition Regimes and Development of the Mixed Layer  

Science Conference Proceedings (OSTI)

Results are presented from a large eddy simulation (LES) and wind tunnel study of the turbulence regime in a horizontally evolving sheared atmospheric convective boundary layer (CBL) capped by a temperature inversion. The wind tunnel part of the ...

E. Fedorovich; F. T. M. Nieuwstadt; R. Kaiser

2001-01-01T23:59:59.000Z

177

Characteristics of Langmuir Turbulence in the Ocean Mixed Layer  

Science Conference Proceedings (OSTI)

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

Alan L. M. Grant; Stephen E. Belcher

2009-08-01T23:59:59.000Z

178

Turbulent Mixing with Chemical Reaction in the Planetary Boundary Layer  

Science Conference Proceedings (OSTI)

Detailed statistics of the fluctuating concentration field produced by large-eddy simulations (LES) of the chemically reactive mixing of two species in a convectively driven mixed layer are presented. The effect of the turbulent mixing on the ...

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

1994-07-01T23:59:59.000Z

179

Subsiding Shells around Shallow Cumulus Clouds  

Science Conference Proceedings (OSTI)

In this study large-eddy simulations (LES) are used to gain more knowledge on the shell of subsiding air that is frequently observed around cumulus clouds. First, a detailed comparison between observational and numerical results is presented to ...

Thijs Heus; Harm J. J. Jonker

2008-03-01T23:59:59.000Z

180

Numerical and Experimental Investigation of the Neutral Atmospheric Surface Layer  

Science Conference Proceedings (OSTI)

This study combines the experimental measurements with large-eddy simulation (LES) data of a neutral planetary boundary layer (PBL) documented by a 60-m tower instrumented with eight sonic anemometers, and a high-resolution Doppler lidar during ...

Philippe Drobinski; Pierre Carlotti; Jean-Luc Redelsperger; Valery Masson; Robert M. Banta; Rob K. Newsom

2007-01-01T23:59:59.000Z

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

Relating Eulerian and Lagrangian Statistics for the Turbulent Dispersion in the Atmospheric Convective Boundary Layer  

Science Conference Proceedings (OSTI)

Eulerian and Lagrangian statistics in the atmospheric convective boundary layer (CBL) are studied by means of large eddy simulation (LES). Spectra analysis is performed in both the Eulerian and Lagrangian frameworks, autocorrelations are ...

Alessandro Dosio; Jordi Vil Guerau de Arellano; Albert A. M. Holtslag; Peter J. H. Builtjes

2005-04-01T23:59:59.000Z

182

Multidimensional Longwave Forcing of Boundary Layer Cloud Systems  

Science Conference Proceedings (OSTI)

The importance of multidimensional (MD) longwave radiative effects on cloud dynamics is evaluated in an eddy-resolving model (ERM)the two-dimensional analog to large-eddy simulation (LES)framework employing multidimensional radiative transfer [...

David B. Mechem; Yefim L. Kogan; Mikhail Ovtchinnikov; Anthony B. Davis; K. Franklin Evans; Robert G. Ellingson

2008-12-01T23:59:59.000Z

183

Top-Down, Bottom-Up Diffusion Experiments in a Water Convection Tank  

Science Conference Proceedings (OSTI)

Large-eddy simulation (LES) results indicate that turbulent scalar diffusion in the convective atmospheric boundary layer (CBL) has interesting properties. A scalar introduced into the bottom of the CBL with no flux through the top (bottom-up ...

M. Piper; J. C. Wyngaard; W. H. Snyder; R. E. Lawson Jr.

1995-10-01T23:59:59.000Z

184

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

Science Conference Proceedings (OSTI)

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

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

2012-11-01T23:59:59.000Z

185

Asymmetric Tidal Mixing due to the Horizontal Density Gradient  

Science Conference Proceedings (OSTI)

Stratification and turbulent mixing exhibit a floodebb tidal asymmetry in estuaries and continental shelf regions affected by horizontal density gradients. The authors use a large-eddy simulation (LES) model to investigate the penetration of a ...

Ming Li; John Trowbridge; Rocky Geyer

2008-02-01T23:59:59.000Z

186

Critical Test of the Validity of MoninObukhov Similarity during Convective Conditions  

Science Conference Proceedings (OSTI)

A recent study of convective boundary layer characteristics performed with large eddy simulation technique (LES) has demonstrated unexpected influence of the depth of the boundary layer on surface layer characteristics. The present study tests ...

Cecilia Johansson; Ann-Sofi Smedman; Ulf Hgstrm; James G. Brasseur; Samir Khanna

2001-06-01T23:59:59.000Z

187

Horizontal Momentum Diffusion in GCMs Using the Dynamic Smagorinsky Model  

Science Conference Proceedings (OSTI)

A dynamic version of Smagorinskys diffusion scheme is presented that is applicable for large-eddy simulations (LES) of the atmospheric dynamics. The approach is motivated (i) by the incompatibility of conventional hyperdiffusion schemes with the ...

Urs Schaefer-Rolffs; Erich Becker

2013-03-01T23:59:59.000Z

188

Scale dependency of total water variance, and its implication for cloud parameterizations  

Science Conference Proceedings (OSTI)

The scale dependency of variance of total water mixing ratio is explored by analyzing data from a General Circulation Model (GCM), a Numerical Weather Prediction Model (NWP) and Large Eddy Simulations (LES). For clarification Direct Numerical ...

Vera Schemann; Bjorn Stevens; Verena Grtzun; Johannes Quaas

189

Evaluation of Parametric Assumptions for Shallow Cumulus Convection  

Science Conference Proceedings (OSTI)

A large-eddy simulation (LES) model has been utilized to study nonprecipitating Shallow Convective clouds such as observed during the undisturbed BOMEX period in the trade wind areas. By choosing a realistic large-scale forcing the authors have ...

A. P. Siebesma; J. W. M. Cuijpers

1995-03-01T23:59:59.000Z

190

Model Impacts of Entrainment and Detrainment Rates in Shallow Cumulus Convection  

Science Conference Proceedings (OSTI)

A mass flux parameterization scheme for shallow cumulus convection is evaluated for a case based on observations and large eddy simulation (LES) results for the Barbados Oceanographic and Meteorological Experiment (BOMEX). The mass flux scheme is ...

A. P. Siebesma; A. A. M. Holtslag

1996-08-01T23:59:59.000Z

191

A New Second-Order Turbulence Closure Scheme for the Planetary Boundary Layer  

Science Conference Proceedings (OSTI)

A new turbulence formulation for the planetary boundary layer (PBL) is presented and compared with large-eddy simulations (LES) for the dry PBL. The new scheme contains a prognostic equation for the turbulent kinetic energy. Other second-order ...

K. Abdella; N. McFarlane

1997-07-01T23:59:59.000Z

192

Aerosol Impacts on the Diurnal Cycle of Marine Stratocumulus  

Science Conference Proceedings (OSTI)

Recent large-eddy simulation (LES) studies of the impact of aerosol on the dynamics of nocturnal marine stratocumulus revealed that, depending on the large-scale forcings, an aerosol-induced increase of the droplet concentration can lead to ...

Irina Sandu; Jean-Louis Brenguier; Olivier Geoffroy; Odile Thouron; Valery Masson

2008-08-01T23:59:59.000Z

193

Relative Humidity as an Indicator for Cloud Formation over Heterogeneous Land Surfaces  

Science Conference Proceedings (OSTI)

The influence of land surface heterogeneity on potential cloud formation is investigated using relative humidity as an indicator. This is done by performing numerical experiments using a large-eddy simulation model (LES). The land surface in the ...

Chiel C. van Heerwaarden; Jordi Vil Guerau de Arellano

2008-10-01T23:59:59.000Z

194

Dispersion of a Passive Tracer in Buoyancy- and Shear-Driven Boundary Layers  

Science Conference Proceedings (OSTI)

By means of finescale modeling [large-eddy simulation (LES)], the combined effect of thermal and mechanical forcing on the dispersion of a plume in a convective boundary layer is investigated. Dispersion of a passive tracer is studied in various ...

Alessandro Dosio; Jordi Vil-Guerau de Arellano; Albert A. M. Holtslag; Peter J. H. Builtjes

2003-08-01T23:59:59.000Z

195

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

196

A Simple Parameterization for Detrainment in Shallow Cumulus  

Science Conference Proceedings (OSTI)

For a wide range of shallow cumulus convection cases, large-eddy simulation (LES) model results have been used to investigate lateral mixing as expressed by the fractional entrainment and fractional detrainment rates. It appears that the ...

Wim C. de Rooy; A. Pier Siebesma

2008-02-01T23:59:59.000Z

197

The Impact of Chemistry on Flux Estimates in the Convective Boundary Layer  

Science Conference Proceedings (OSTI)

Different higher-order flux closures are compared for two chemistry cases using a large eddy simulation (LES) model for the convective atmospheric boundary layer. Both a simple chemistry case and a photochemistry case more representative for ...

Arthur C. Petersen

2000-10-01T23:59:59.000Z

198

A Simple Parameterization of Cloud Water Related Variables for Use in Boundary Layer Models  

Science Conference Proceedings (OSTI)

A simple parameterization of cloud water related variables has been developed which can be used in meteorological models that use a prognostic equation for the turbulent kinetic energy. Based on the results of large-eddy simulations (LES), ...

J. W. M. Cuijpers; P. Bechtold

1995-07-01T23:59:59.000Z

199

LES based urban dispersal predictions for consequence management  

Science Conference Proceedings (OSTI)

It is unlikely that we will ever have a deterministic predictive framework for the study of flows in urban scale scenarios purely based on computational fluid dynamics. This is due to the inherent difficulty in modeling and validating all relevant physical sub-processes and acquiring all the necessary and relevant boundary condition information. On the other hand, this case is representative of very fundamental ones for which whole-domain scalable laboratory (or field) studies are impossible or very difficult, but for which it is also crucial to develop predictability. In this paper, we discuss a framework for detailed dispersal predictions in urban and regional settings based on effective linkage of strong motion codes - capable of simulating detailed energetic and contaminant sources, and large-eddy simulation - capable of emulating contaminant transport due to wind and turbulence fields in built-up areas. Challenging technical aspects of the simulation approach are outlined and recent progress is reviewed in th is context.

Grinstein, Fernando Franklin [Los Alamos National Laboratory; Bos, Randall [Los Alamos National Laboratory; Dey, Tom [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

200

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

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

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

202

Simulations of Turbulent Flows with Strong Shocks and Density Variations: Final Report  

SciTech Connect

The target of this SciDAC Science Application was to develop a new capability based on high-order and high-resolution schemes to simulate shock-turbulence interactions and multi-material mixing in planar and spherical geometries, and to study Rayleigh-Taylor and Richtmyer-Meshkov turbulent mixing. These fundamental problems have direct application in high-speed engineering flows, such as inertial confinement fusion (ICF) capsule implosions and scramjet combustion, and also in the natural occurrence of supernovae explosions. Another component of this project was the development of subgrid-scale (SGS) models for large-eddy simulations of flows involving shock-turbulence interaction and multi-material mixing, that were to be validated with the DNS databases generated during the program. The numerical codes developed are designed for massively-parallel computer architectures, ensuring good scaling performance. Their algorithms were validated by means of a sequence of benchmark problems. The original multi-stage plan for this five-year project included the following milestones: 1) refinement of numerical algorithms for application to the shock-turbulence interaction problem and multi-material mixing (years 1-2); 2) direct numerical simulations (DNS) of canonical shock-turbulence interaction (years 2-3), targeted at improving our understanding of the physics behind the combined two phenomena and also at guiding the development of SGS models; 3) large-eddy simulations (LES) of shock-turbulence interaction (years 3-5), improving SGS models based on the DNS obtained in the previous phase; 4) DNS of planar/spherical RM multi-material mixing (years 3-5), also with the two-fold objective of gaining insight into the relevant physics of this instability and aiding in devising new modeling strategies for multi-material mixing; 5) LES of planar/spherical RM mixing (years 4-5), integrating the improved SGS and multi-material models developed in stages 3 and 5. This final report is outlined as follows. Section 2 shows an assessment of numerical algorithms that are best suited for the numerical simulation of compressible flows involving turbulence and shock phenomena. Sections 3 and 4 deal with the canonical shock-turbulence interaction problem, from the DNS and LES perspectives, respectively. Section 5 considers the shock-turbulence inter-action in spherical geometry, in particular, the interaction of a converging shock with isotropic turbulence as well as the problem of the blast wave. Section 6 describes the study of shock-accelerated mixing through planar and spherical Richtmyer-Meshkov mixing as well as the shock-curtain interaction problem In section 7 we acknowledge the different interactions between Stanford and other institutions participating in this SciDAC project, as well as several external collaborations made possible through it. Section 8 presents a list of publications and presentations that have been generated during the course of this SciDAC project. Finally, section 9 concludes this report with the list of personnel at Stanford University funded by this SciDAC project.

Sanjiva Lele

2012-10-01T23:59:59.000Z

203

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

DOE Green Energy (OSTI)

In this project, an advanced computational software tool will be developed for the design of low emission combustion systems required for Vision 21 clean energy plants. This computational tool will utilize Large Eddy Simulation (LES) methods to predict the highly transient nature of turbulent combustion. The time-accurate software will capture large scale transient motion, while the small scale motion will be modeled using advanced subgrid turbulence and chemistry closures. This three-year project is composed of: Year 1--model development/implementation, Year 2--software alpha validation, and Year 3--technology transfer of software to industry including beta testing. In this first year of the project, subgrid models for turbulence and combustion are being developed through university research (Suresh Menon-Georgia Tech and J.-Y. Chen- UC Berkeley) and implemented into a leading combustion CFD code, CFD-ACE+. The commercially available CFDACE+ software utilizes unstructured , parallel architecture and 2nd-order spatial and temporal numerics. To date, the localized dynamic turbulence model and reduced chemistry models (up to 19 species) for natural gas, propane, hydrogen, syngas, and methanol have been incorporated. The Linear Eddy Model (LEM) for subgrid combustion-turbulence interaction has been developed and implementation into CFD-ACE+ has started. Ways of reducing run-time for complex stiff reactions is being studied, including the use of in situ tabulation and neural nets. Initial validation cases have been performed. CFDRC has also completed the integration of a 64 PC cluster to get highly scalable computing power needed to perform the LES calculations ({approx} 2 million cells) in several days. During the second year, further testing and validation of the LES software will be performed. Researchers at DOE-NETL are working with CFDRC to provide well-characterized high-pressure test data for model validation purposes. To insure practical, usable software is developed, a consortium of gas turbine and industrial burner manufacturers has been established to guide and direct the software development/validation effort. The consortium members include Siemens- Westinghouse, GE Power Systems, Pratt & Whitney, Rolls-Royce, Honeywell, Solar, Coen, McDermott, Vapor Power, Woodward FST, Parker Hannifin, John Zink, RamGen Power, Virginia Tech, DOE-NETL, Air Force Research Laboratory, DOE-ANL, and NASA GRC. Annual consortium meetings are being held in Huntsville, with the 2nd meeting scheduled for January 31-February 1, 2002. 2 Benefits of the program will include the ability to assess complex combustion challenges such as combustion instability, lean blowout, flashback, emissions and the effect of fuel type on performance. The software will greatly reduce development costs and the time cycle of combustor development. And perhaps the greatest benefit will be that the software will stimulate new, creative ideas to solve the combustion challenges of the Vision 21 plant.

Cannon, Steven M.; Adumitroaie, Virgil; McDaniel, Keith S.; Smith, Clifford E.

2001-11-06T23:59:59.000Z

204

A filtered mass density function approach for modeling separated two-phase flows for LES II: Simulation of a droplet laden  

E-Print Network (OSTI)

and evaporation/reaction of dilute particulate­gas two-phase flows is extremely impor- tant in many natural the importance of variations in composition space in the phase-coupling terms. ? 2008 Elsevier Ltd. All rights reserved. Keywords: Two-phase flow; FDF methods; Temporal mixing layer; LES; Droplet gas flow 1

DesJardin, Paul E.

205

et les mtadonnes CMIP5 Sieste Globc -Marie-Pierre Moine -2 dcembre 2010  

E-Print Network (OSTI)

outils de création d'instances CIM (WP6) Questionnaire CMIP5 : collecte des métadonnées sur les modèles et simulations) Interface d'instanciation du CIM : Geonetwork Développer des services d'accès et produit ces données; les modèles utilisés pour ces simulations. CIM : « Common Information Model » Ce

206

Diurnal wind cycles forcing inertial oscillations: a latitude-dependent resonance phenomenon  

Science Conference Proceedings (OSTI)

The latitudinal dependence of inertial oscillation (IO) in a diurnally-evolving atmospheric boundary layer (ABL) is examined using a large eddy simulation (LES). Previous studies that used LES were unable to simulate such an ABL on a time scale of ...

Ryosuke Shibuya; Kaoru Sato; Mikio Nakanishi

207

ARM - Publications: Science Team Meeting Documents  

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

Radar Observations of Large-Eddy Circulations and Turbulence in Boundary Radar Observations of Large-Eddy Circulations and Turbulence in Boundary Layer Clouds Albrecht, B.A. and Kollias, P., Umiversity of Miami Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting With the development and application of Doppler short wavelength radars, there has been an increased capability for explicitly resolving the vertical structure of boundary layer cloud circulations. Further, Doppler mm-wavelength radars used in a vertically pointing mode can provide information on the turbulence structure within the cloud volume sampled by the radar. Since these radar large eddy observations (LEO) are of the same resolution as that of Large Eddy Simulation models, they provide a means for explicitly evaluating LES (LEO for LES). Further the radar observations

208

Evaluation of Turbulent Transport and Dissipation Closures in Second-Order Modeling  

Science Conference Proceedings (OSTI)

We show that the turbulence statistics from our (96)3 large-eddy-simulation (LES) studies of a convective boundary layer are in excellent agreement with those from the DeardorffWillis laboratory convection tank. Using these LES data, we evaluate ...

Chin-Hoh Moeng; John C. Wyngaard

1989-07-01T23:59:59.000Z

209

Interview of Les Hiatt  

E-Print Network (OSTI)

Interview of Les Hiatt by Alan Macfarlane on 14th July 2005 0:05:07 Introduction; born 1931 in Gilgandra, New South Wales; father son of English migrants; his father became a miller; father became a book-keeper and later manager of flour mill...

Hiatt, Les

2005-08-24T23:59:59.000Z

210

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

211

On the Factors Modulating the Stratocumulus to Cumulus Transitions  

Science Conference Proceedings (OSTI)

Large-eddy simulation (LES) is used to explore the role of various processes in regulating the stratocumulus to cumulus transition (SCT). Simulations are based on a composite case derived from a Lagrangian analysis of 2 yr of data from the ...

Irina Sandu; Bjorn Stevens

2011-09-01T23:59:59.000Z

212

A filtered tabulated chemistry model for LES of premixed combustion  

E-Print Network (OSTI)

A filtered tabulated chemistry model for LES of premixed combustion B. Fiorinaa , R. Vicquelina to turbulent combustion regimes by including subgrid scale wrinkling effects in the flame front propagation Simulation, Turbulent premixed combustion, Tabulated chemistry 1. Introduction Flame ignition and extinction

Paris-Sud XI, Université de

213

A closure for updraft-downdraft representation of subgrid-scale fluxes in cloud-resolving models  

Science Conference Proceedings (OSTI)

A closure relationship between subgrid-scale (SGS) updraft-downdraft differences and resolvable-scale (RS) variables is proposed and tested for cloud-resolving models (CRMs), based on a data analysis of a large-eddy simulation (LES) of deep ...

Chin-Hoh Moeng

214

Diuron in Surface Runoff and Tile Drainage from Two Grass-Seed Fields David E. Rupp,* R. Edward Peachey, Kristina L. Warren, and John S. Selker  

E-Print Network (OSTI)

it used a simpler, two-phase-flow single burner with three levels of refinement (4­, 8­, and 16­million (but are not limited to) aircraft landing gear, wind turbines, bridges, industrial heat exchangers combustor. This research is focused on Large Eddy Simulation (LES) of gas turbine engines with the inclusion

Selker, John

215

Stratified Turbulence in the Atmosphere and Oceans: A New Subgrid Model  

Science Conference Proceedings (OSTI)

Turbulence in a stratified medium is studied with emphasis on stable stratification, as it occurs in the atmosphere and oceans, and on the construction of a subgrid model (SGS) for use in large eddy simulation (LES). The two basic assumptions of ...

V. M. Canuto; F. Minotti

1993-07-01T23:59:59.000Z

216

Modeling Supersaturation and Subgrid-Scale Mixing with Two-Moment Bulk Warm Microphysics  

Science Conference Proceedings (OSTI)

This paper describes further developments of a two-moment warm rain bulk microphysics scheme suitable for addressing the indirect impact of atmospheric aerosols on ice-free clouds in large-eddy simulation (LES) models. The emphasis is on the ...

Hugh Morrison; Wojciech W. Grabowski

2008-03-01T23:59:59.000Z

217

Time Scales of the Trade Wind Boundary Layer Adjustment  

Science Conference Proceedings (OSTI)

The adjustment of the trade wind atmospheric boundary layer to an abrupt sea surface warming is investigated using a large-eddy simulation (LES) and two simple bulk models: a mixed-layer model (MLM), and a model based on the mixing-line hypothesis ...

Gilles Bellon; Bjorn Stevens

2013-04-01T23:59:59.000Z

218

High-Resolution Numerical Modeling of Thermally Driven Slope Winds in a Valley with Strong Capping  

Science Conference Proceedings (OSTI)

The complete daynight cycle of the circulation over a slope under simplified idealized boundary conditions is investigated by means of large-eddy simulations (LES). The thermal forcing is given with a time-varying law for the surface ...

Franco Catalano; Antonio Cenedese

2010-09-01T23:59:59.000Z

219

Les cryptorchidies opres selon la technique de Stephen-Fowler.  

E-Print Network (OSTI)

??Cette thse traite de la cryptorchidie. Nous abordons les diverses approches thrapeutiques en les comparant les unes aux autres. Le rle diagnostique et thrapeutique de (more)

Bazarbachi, Dania

220

Albany, OR * Anchorage, AK * Morgantown, WV * Pittsburgh, PA * Sugar Land, TX  

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

Large Eddy Simulation Modeling of Large Eddy Simulation Modeling of Flashback and Flame Stabilization in Hydrogen-Rich Gas Turbines using a Hierarchical Validation Approach- University of Texas at Austin Background The focus of this project is the development of advanced large eddy simulation (LES)-based combustion modeling tools that can be used to design low emissions combustors burning high hydrogen content fuels. The University of Texas at Austin (UT) will develop models for two key topics: (1) flame stabilization, lift- off, and blowout when fuel-containing jets are introduced into a crossflow at high pressure, and (2) flashback dynamics of lean premixed flames with detailed description of flame propagation in turbulent core and near-wall flows. The jet- in-crossflow (JICF) configuration is widely used for rapid mixing of reactants

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

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

222

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

223

Topical report : CFD analysis for the applicability of the natural convection shutdown heat removal test facility (NSTF) for the simulation of the VHTR RCCS.  

DOE Green Energy (OSTI)

The Very High Temperature gas cooled reactor (VHTR) is one of the GEN IV reactor concepts that have been proposed for thermochemical hydrogen production and other process-heat applications like coal gasification. The United States Department of Energy has selected the VHTR for further research and development, aiming to demonstrate emissions-free electricity and hydrogen production at a future time. One of the major safety advantages of the VHTR is the potential for passive decay heat removal by natural circulation of air in a Reactor Cavity Cooling System (RCCS). The air-side of the RCCS is very similar to the Reactor Vessel Auxiliary Cooling System (RVACS) that has been proposed for the PRISM reactor design. The design and safety analysis of the RVACS have been based on extensive analytical and experimental work performed at ANL. The Natural Convection Shutdown Heat Removal Test Facility (NSTF) at ANL that simulates at full scale the air-side of the RVACS was built to provide experimental support for the design and analysis of the PRISM RVACS system. The objective of this work is to demonstrate that the NSTF facility can be used to generate RCCS experimental data: to validate CFD and systems codes for the analysis of the RCCS; and to support the design and safety analysis of the RCCS. At this time no reference design is available for the NGNP. The General Atomics (GA) gas turbine - modular helium reactor (GT-MHR) has been used in many analyses as a starting reference design. In the GT-MHR the reactor outlet temperature is 850 C, while the target outlet reactor temperature in VHTR is 1000 C. VHTR scoping studies with a reactor outlet temperature of 1000 C have been performed at GA and INEL. Although the reactor outlet temperature in the VHTR is significantly higher than in the GT-MHR, the peak temperature in the reactor vessel (which is the heat source for the RCCS) is not drastically different. In this work, analyses have been performed using reactor vessel temperatures from the GT-MHR design, and the VHTR scoping studies. To demonstrate the applicability of the NSTF facility for full scale simulation of the RCCS the following approach was used. CFD analyses were performed of the RCCS and of its simulation at NSTF to demonstrate that: all significant fluid flow and heat transfer phenomena in the RCCS can be simulated at NSTF; and RCCS simulations at NSTF can cover the whole range of variation of the parameters describing these important phenomena in the RCCS. In CFD analyses, the simulation of turbulence is one of the most significant challenges. Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) of turbulence in large scale systems require excessive computational resources. The use of the Low-Re number k-{var_epsilon} model, which resolves the boundary layer, is computationally expensive in studies where many simulations have to be performed. In Ref. 2 it was shown that in the RCCS, heat transfer coefficient predictions of the high-Re number k-{var_epsilon} model are closer to those of the low-Re number model than those of heat transfer correlations. In this work, the standard high-Re number k-{var_epsilon} was used to simulate turbulence, and all analyses were performed with the CFD code STARCD.

Tzanos, C. P. (Nuclear Engineering Division)

2007-05-16T23:59:59.000Z

224

Argonne TTRDC - Engines - Multi-Dimensional Modeling - LES  

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

The main questions that need to be addressed are: Can LES provide further insights on spray and combustion processes? Does LES improve qualitative andor quantitative...

225

LES ACIDES GRAS TRANS DU BEURRE II.  

E-Print Network (OSTI)

origine est essentiellement endogène car les aliments naturels habituellement distribués aux vaches) au cours de l'hydro- génation biologique portant sur les acides oléique, linoléique et linolénique

Recanati, Catherine

226

LES/PDF based modeling of sootturbulence interactions in turbulent flames  

E-Print Network (OSTI)

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

Raman, Venkat

227

LES THORIES LINGUISTIQUES, LES PRATIQUES PDAGOGIQUES ET L'ACQUISITION DE LA DTERMINATION NOMINALE EN ANGLAIS CHEZ LES APPRENANTS FRANCOPHONES.  

E-Print Network (OSTI)

??Parmi les causes des difficults que tout apprenant rencontre lors du travail d'apprentissage en milieu scolaire d'une langue seconde comme l'anglais, on peut mettre en (more)

Sournin Dufosse, Sophie

2007-01-01T23:59:59.000Z

228

Les reprsentations de lhomosexualit dans la tlsrie Les hauts et les bas de Sophie Paquin .  

E-Print Network (OSTI)

??L'cran de tlvision peut tre peru comme tant un miroir refltant les climats sociaux et politiques d'une socit. Alors, que reprsente concrtement le contenu de (more)

Vacias, Vivianne

2013-01-01T23:59:59.000Z

229

SUR LES RADIOLMENTS FORMS DANS L'URANIUM IRRADI PAR LES NEUTRONS. II Par IRNE CURIE et PAUL SAVITCH.  

E-Print Network (OSTI)

SUR LES RADIO?L?MENTS FORM?S DANS L'URANIUM IRRADI? PAR LES NEUTRONS. II Par IR?NE CURIE et PAUL SAVITCH. Institut du Radium. Laboratoire Curie. Sommaire. 2014 Il se forme dans l'uranium irradié par les l'irra- diation de l'uranium par les neutrons, résultats dont nous avons vérifié une partie. Ces

Paris-Sud XI, Université de

230

Les micro-nanotechnologies pour les systmes hyperfrquences: au-del des conventions.  

E-Print Network (OSTI)

??L'volution de notre socit est spectaculaire. Les nouvelles technologies apportent sans cesse des bouleversements dans nos vies, dont nous n'avons d'ailleurs pas toujours conscience tellement (more)

Grenier, Katia

2010-01-01T23:59:59.000Z

231

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

232

Building and Fire Publications  

Science Conference Proceedings (OSTI)

... S.; Baum, HR; CFD Simulation of a 2.5 MW Oil Pool Fire in a Nuclear Power Plant Containment Building Using Multi-Block Large Eddy Simulation. ...

233

A Pilot-plant Scale Test on DRI Preparation from High-alumina ...  

Science Conference Proceedings (OSTI)

... by Microwave Heating Large Eddy Simulation for Turbulent Flow in a Dissipative Ladle Shroud ... Thermochemical Simulation of Cu-Ni Smelting Operations.

234

tude des pratiques linguistiques en camfranglais dans les centres urbains camerounais : le cas de Yaound.  

E-Print Network (OSTI)

??Mettant contribution les principes de la linguistique distributionnelle (aliments par les acquis de la smantaxe) et lapproche de la linguistique de corpus, cette tude (more)

Eloundou Eloundou, Venant

2011-01-01T23:59:59.000Z

235

SUR LES PRODUITS SCALAIRES DE FONCTIONS D'ONDE ET LES INTGRALES DE FOURIER RCIPROQUES EN MCANIQUE ONDULATOIRE RELATIVISTE  

E-Print Network (OSTI)

. Olivier Costa de Beauregard dans son étude explicitement covariante des solutions de l'équation de Gordon-SEPTEMBRE 1955, Introduction. - Dans de nombreux tra- vaux [2], [3], [4], M. Olivier Costa de Beauregard a défini théorie quantique des champs ». Tous les raisonnements de M. Costa de Beauregard postulaient que les

Paris-Sud XI, Université de

236

es recherches sur les capacits linguistiques des nourrissons ont  

E-Print Network (OSTI)

Médecine & enfance L es recherches sur les capacités linguistiques des nourrissons ont été lancées linguistiques pré- coces [1]. Ces auteurs ont ainsi constaté que les nourrissons de un et trois mois étaient'identification correcte, en fonction de l'âge et de l'expérience linguistique des sujets, de deux contrastes phonémiques

Dehaene-Lambertz, Ghislaine

237

Etudes molculaires et culturales de boues issues de bioracteurs anarobies msothermiques traitant le phosphogypse : Isolement et caractrisation de nouveaux genres chez les thermotogales.  

E-Print Network (OSTI)

??Les reprsentants de l'ordre des Thermotogales se trouvent gnralement dans les puits ptroliers et les sources hydrothermales aquatiques et terrestres. Rcemment, des tudes molculaires bases (more)

Ben Hania, Wajdi

2012-01-01T23:59:59.000Z

238

Three-dimensional hydrodynamic simulations of the combustion of a neutron star into a quark star  

Science Conference Proceedings (OSTI)

We present three-dimensional numerical simulations of turbulent combustion converting a neutron star into a quark star. Hadronic matter, described by a microphysical finite-temperature equation of state, is converted into strange quark matter. We assume this phase, represented by a bag-model equation of state, to be absolutely stable. Following the example of thermonuclear burning in white dwarfs leading to type Ia supernovae, we treat the conversion process as a potentially turbulent deflagration. Solving the nonrelativistic Euler equations using established numerical methods we conduct large eddy simulations including an elaborate subgrid scale model, while the propagation of the conversion front is modeled with a level-set method. Our results show that for large parts of the parameter space the conversion becomes turbulent and therefore significantly faster than in the laminar case. Despite assuming absolutely stable strange quark matter, in our hydrodynamic approximation an outer layer remains in the hadronic phase, because the conversion front stops when it reaches conditions under which the combustion is no longer exothermic.

Herzog, Matthias; Roepke, Friedrich K. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg, Emil-Fischer-Str. 31, D-97074 Wuerzburg (Germany)

2011-10-15T23:59:59.000Z

239

Dynamic LES Modeling of a Diurnal Cycle  

Science Conference Proceedings (OSTI)

The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case study is simulated using the recently proposed locally averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables ...

Sukanta Basu; Jean-Franois Vinuesa; Andrew Swift

2008-04-01T23:59:59.000Z

240

L'infiltration dans les cnes de djection : la basse valle de la Tarentaise, Savoie - Alpes franaises.  

E-Print Network (OSTI)

??Dans les grandes valles alpines, les cnes de djection tiennent une place importante. De nombreuses tudes ponctuelles ont montr leur rle dans l'alimentation des nappes (more)

Carret, Jean Paul

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

Les schmas de test : une abstraction pour la gnration de tests de conformit et pour la mesure de couverture.  

E-Print Network (OSTI)

??L'activit de test est une partie de plus en plus importante dans les dveloppements logiciels. Cette activit de test est souvent longue et rptitive, les (more)

Bontron, Pierre

242

Mthode de Test et Conception en Vue du Test pour les Rseaux sur Puce Asynchrones : Application au Rseau ANOC.  

E-Print Network (OSTI)

??Les rseaux sur puce (NoC : Network on Chip) et les architectures GALS (Globalement Asynchrone Localement Synchrone) sont deux nouveaux paradigmes de communication pour (more)

Tran, Xuan Tu

243

LES of Sandia Flame D with Eulerian PDF and Finite-Rate Chemistry  

E-Print Network (OSTI)

Barlow, R. S. , 2003. Sandia piloted CH 4 /air ?ame D data -LES of Sandia Flame D with Eulerian PDF and Finite-RatePaper: 05F-33 LES of Sandia Flame D with Eulerian PDF and

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

244

Micro et Nano Physique Cours 1 : les principes de la  

E-Print Network (OSTI)

Micro et Nano Physique (MNP) Cours 1 : les principes de la mécanique quantique (approche conceptuelle) #12;Micro et nano physique (MNP)page 1 Pourquoi un cours sur la physique microscopique ? · Une fondamentaux à la base des technologies du numérique #12;Micro et nano physique (MNP)page 2 Organisation de l

Rioul, Olivier

245

Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award  

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

Locally Employed Staff (LES)/Foreign Service National (FSN) Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award The Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award is designed to recognize special contributions made by the Department's LES/FSN's in achieving the U.S. Department of Energy's (DOE) and United States Government's (USG) foreign policy goals and objectives. The LES/FSN of the Year Award is the Department's most prestigious award for non- Federal locally employed staff serving the Department overseas, and recognizes their outstanding achievements for the period of 1 October through 30 September each year. This

246

From Grains to Planetesimals: Les Houches Lecture  

E-Print Network (OSTI)

This pedagogical review covers an unsolved problem in the theory of protoplanetary disks: the growth of dust grains into planetesimals, solids at least a kilometer in size. I summarize timescale constraints imposed on planetesimal formation by circumstellar disk observations, analysis of meteorites, and aerodynamic radial migration. The infall of ~meter-sized solids in a hundred years is the most stringent constraint. I review proposed mechanisms for planetesimal formation. Collisional coagulation models are informed by laboratory studies of microgravity collisions. The gravitational collapse (or Safronov-Goldreich-Ward) hypothesis involves detailed study of the interaction between solid particles and turbulent gas. I cover the basics of aerodynamic drag in protoplanetary disks, including radial drift and vertical sedimentation. I describe various mechanisms for particle concentration in gas disks -- including turbulent pressure maxima, drag instabilities and long-lived anticylonic vortices. I derive a general result for the minimum size for a vortex to trap particles in a sub-Keplerian disk. Recent numerical simulations demonstrate that particle clumping in turbulent protoplanetary disks can trigger gravitational collapse. I discuss several outstanding issues in the field.

Andrew Youdin

2008-07-07T23:59:59.000Z

247

Etudier les lettres l'Universit de Genve  

E-Print Network (OSTI)

25. Langues et civilisations de la mésopotamie 26. Linguistique 27. Littérature comparée 28, linguistique et littéraire axée sur les structures formelles, logiques et expressives du texte, ainsi qu lettres offre également la possibilité d'effectuer des certi- ficats de spécialisation en linguistique, en

Halazonetis, Thanos

248

Dans le voisinage de Joachimsthal, situ dans la partie la plus leve du versant sud, les filons les plus  

E-Print Network (OSTI)

composition de ces minerais d'urane et il se produit des arséniates, des sulfates d'uranium, etc. La mine de Weisser Hirsch près de Schnccbcrg (Saxe) est remarquable par les espèces minéralogiques ce qui précède que si l'uranium est par- fois localisé dans quelques régions du globe, où il existe

Paris-Sud XI, Université de

249

Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year  

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

Locally Employed Staff (LES)/Foreign Service National (FSN) of the Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award The Locally Employed Staff (LES)/Foreign Service National (FSN) of the Year Award is designed to recognize special contributions made by the Department's LES/FSN's in achieving the U.S. Department of Energy's (DOE) and United States Government's (USG) foreign policy goals and objectives. The LES/FSN of the Year Award is the Department's most prestigious award for non-Federal locally employed staff serving the Department overseas, and recognizes their outstanding achievements for the period of 1 October through 30 September each year. This special award program has been established in accordance with the requirements of

250

Les lHa srin sde brgyad et le probleme de leur categorisation - Une interpretation  

E-Print Network (OSTI)

reconnatre ventuellement la prsence ou labsence detelle ou telle entit lha srin dans un rituel, sont pralablement dfinies, la fois par les enquteurs ethnologues et par les usagers, travers un lan-gage naturel dont les proprits conventionnelles... solides ou entrelacs de fils destins figurer des entits terribles (formes de Mahakala ou mgon po), insistent surle choix de matriaux slectionns en fonction de leurs proprits : fils decoton entrelacs car lentrelacs doit laisser passer la lumire...

Steinmann, Brigitte

2003-01-01T23:59:59.000Z

251

L'antisexisme linguistique dans les brochures libertaires : pratiques d'criture et mtadiscours.  

E-Print Network (OSTI)

??Des transgressions du genre apparaissent dans les brochures libertaires. Le masculin et le fminin y sont chambards et ces modifications apportes la langue font (more)

Abbou, Julie

2011-01-01T23:59:59.000Z

252

Modeling & Simulation  

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

Modeling & Simulation Modeling & Simulation Research into alternative forms of energy, especially energy security, is one of the major national security imperatives of this...

253

Slide 1  

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

INTRODUCTION INTRODUCTION Boundary layer clouds (BLCs) have a significant impact on the radiative budget of the Earth but are difficult to represent in climate models. In the past, large eddy simulation (LES) has served as a major role in providing a better understanding of the BLCs and developing parameterizations of cloud turbulence and convection processes. ARM over the years has made a great progress in developing a suite of key remote sensing instruments, such as MMCR and WACR, for observing BLCs under various weather conditions. The primary goal of the ARM LES Testbed (ALT) is to improve parameterizations of BLCs through systematically evaluating LESs using ARM high temporal and spatial resolution cloud radar measurements. To cope with the advanced ARM cloud radar data and fulfill the

254

Minimalist Model of Ice Microphysics in Mixed-phase Stratiform Clouds  

SciTech Connect

The question of whether persistent ice crystal precipitation from super cooled layer clouds can be explained by time-dependent, stochastic ice nucleation is explored using an approximate, analytical model, and a large-eddy simulation (LES) cloud model. The updraft velocity in the cloud defines an accumulation zone, where small ice particles cannot fall out until they are large enough, which will increase the residence time of ice particles in the cloud. Ice particles reach a quasi-steady state between growth by vapor deposition and fall speed at cloud base. The analytical model predicts that ice water content (wi) has a 2.5 power law relationship with ice number concentration ni. wi and ni from a LES cloud model with stochastic ice nucleation also confirm the 2.5 power law relationship. The prefactor of the power law is proportional to the ice nucleation rate, and therefore provides a quantitative link to observations of ice microphysical properties.

Yang, F.; Ovchinnikov, Mikhail; Shaw, Raymond A.

2013-07-28T23:59:59.000Z

255

tude de l'effet d'inhibition du gel induit par les sulfates dans les nuages arctiques l'aide des mesures satellitaires de CloudSat et CALIPSO.  

E-Print Network (OSTI)

??Les sulfates issus de la pollution industrielle d'Eurasie et transports travers la basse troposphre arctique durant l'hiver sont souponns d'altrer les proprits des nuages (more)

Grenier, Patrick

2010-01-01T23:59:59.000Z

256

ARM - Publications: Science Team Meeting Documents  

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

Cloud-Resolving Simulations of Boundary-Layer Cloud Regimes with a Cloud-Resolving Simulations of Boundary-Layer Cloud Regimes with a Third-Order Turbulence Cheng, A.(a,b) and Xu, K.-M.(a), Atmospheric Sciences, NASA Langley Research Center (a), Hampton University (b) Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting LES (large eddy simulation) models can explicitly resolve large turbulent eddies, which contain m ost of the turbulent kinetic energy and do most of the transport in the boundary layer. These edd ies have to be parameterized in cloud-resolving models (CRMs), which have much coarser resolution . A sophisticated turbulent parameterization is needed in order to produce adequate simulations o f cloud processes in CRMs. Most CRMs use a one- and a half-order prognostic turbulent kinetic ene rgy closure. Third-order

257

Sources, production et transfert du carbone organique dissous dans les bassins versants lmentaires sur socle : apports des isotopes stables du carbone.  

E-Print Network (OSTI)

??En dpit de son importance pour les cosystmes aquatiques, l'origine et les mcanismes de production du carbone organique dissous (COD) sont toujours sujets discussion. (more)

Lambert, Thibault

2013-01-01T23:59:59.000Z

258

Influence des caractristiques de la structure de soin sur la prise en charge prinatale chez les femmes bas risque en France.  

E-Print Network (OSTI)

??Si la mdicalisation de la grossesse et de l'accouchement a montr un bnfice chez les femmes haut risque obsttrical, en revanche pour les femmes (more)

Le Ray, Camille

2009-01-01T23:59:59.000Z

259

LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment  

SciTech Connect

Roll clouds, and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Bruemmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds. In an effort to examine the influences of mixed-phase microphysics on the boundary layer evolution of roll clouds during off-ice flow, Olsson and Harrington (2000) used a 2D mesoscale model coupled to a bulk microphysical scheme (see Section 2). Their results showed that mixed-phase clouds produced more shallow boundary layers with weaker turbulence than liquid-phase cases. Furthermore, their results showed that because of th e reduced turbulent drag on the atmosphere in the mixed-phase case, regions of mesoscale divergence in the marginal ice-zone were significantly affected. A follow-up 2D study (Harrington and Olsson 2001) showed that the reduced turbulent intensity in mixed-phase cases was due to precipitation. Ice precipitation caused downdraft stabilization which fed back and caused a reduction in the surface heat fluxes. In this work, we extend the work of Olsson and Harrington (2000) and Harrington and Olsson (2001) by examining the impacts of ice microphysics on roll convection. We will present results that illustrate how microphysics alters roll cloud structure and dynamics.

Greenberg, S.D.; Harrington, J.Y.; Prenni, A.; DeMott, P.

2005-03-18T23:59:59.000Z

260

Network Simulation  

SciTech Connect

A detailed introduction to the design, implementation and use of network simulation tools is presented. The requirements and issues faced in the design of simulators for wired and wireless networks are discussed. Abstractions such as packet- and fluid-level network models are covered. Several existing simulations are given as examples, with details and rationales regarding design decisions presented. Issues regarding performance and scalability are discussed in detail, describing how one can utilize distributed simulation methods to increase the scale and performance of a simulation environment. Finally, a case study of two simulation tools is presented that have been developed using distributed simulation techniques. This text is essential to any student, researcher or network architect desiring a detailed understanding of how network simulation tools are designed, implemented, and used.

Fujimoto, Richard [ORNL; Perumalla, Kalyan S [ORNL; Riley, George F. [Georgia Institute of Technology

2006-01-01T23:59:59.000Z

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

Surface Heterogeneity Effects on Regional-Scale Fluxes in Stable Boundary Layers: Surface Temperature Transitions  

Science Conference Proceedings (OSTI)

Large-eddy simulation, with recently developed dynamic subgrid-scale models, is used to study the effect of heterogeneous surface temperature distributions on regional-scale turbulent fluxes in the stable boundary layer (SBL). Simulations are ...

Rob Stoll; Fernando Port-Agel

2009-02-01T23:59:59.000Z

262

Thermodynamic and Aerosol Controls in Southeast Pacific Stratocumulus  

Science Conference Proceedings (OSTI)

A near-large-eddy simulation approach with size-revolving (bin) microphysics is employed to evaluate the relative sensitivity of southeast Pacific marine boundary layer cloud properties to thermodynamic and aerosol parameters. Simulations are ...

David B. Mechem; Sandra E. Yuter; Simon P. de Szoeke

2012-04-01T23:59:59.000Z

263

Simulation Tools  

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

Building simulation tool screen capture Building simulation tool screen capture Simulation Tools Researchers develop whole-building energy simulation software programs that allow architects and building engineers to design or retrofit buildings for maximum energy efficiency and occupant comfort. Programs developed by researchers include: the EnergyPlus whole building simulation program, the Modelica Buildings library for rapid prototyping and controls design, the Building Controls Virtual Test Bed for co-simulation and for model-based operation, and the GenOpt generic optimization program. Contacts Philip Haves PHaves@lbl.gov (510) 486-6512 Michael Wetter MWetter@lbl.gov (510) 486-6990 Links Simulation Research Group Batteries and Fuel Cells Buildings Energy Efficiency Applications Commercial Buildings

264

Stockage gologique du dioxyde de carbone dans les veines de charbon : du matriau au rservoir.  

E-Print Network (OSTI)

??Les missions de CO2 dans l'atmosphre sont reconnues comme ayant un effet significatif sur le rchauffement climatique. Le stockage gologique de CO2 est largement considr (more)

Nikoosokhan, Saeid

2012-01-01T23:59:59.000Z

265

Les discours sportifs en proie aux nationalismes et l'ethnicisation.  

E-Print Network (OSTI)

??Ce travail a pour objet d'e?tudier les discours sportifs et leurs rapports avec la notion d'identite? a? partir d'un corpus me?diatique re?uni autour de deux (more)

Richard, Arnaud

2009-01-01T23:59:59.000Z

266

Les premires coles autochtones au Qubec : progression, opposition et luttes de pouvoir, 1792-1853.  

E-Print Network (OSTI)

??Ce mmoire s'intresse aux luttes de pouvoir qui ont entour le dveloppement des premires coles pour les Autochtones de la valle du Saint-Laurent, durant la (more)

Chaurette, Mathieu

2011-01-01T23:59:59.000Z

267

Formalisme CSP (Constraint Satisfaction Problem) et localisation de motifs structurs dans les textes gnomiques.  

E-Print Network (OSTI)

??La recherche d'occurrences de gnes d'ARN dans les squences gnomiques est un problme dont l'importance est renouvele par la dcouverte rcente de trs nombreux ARN (more)

Thebault, Patricia

2004-01-01T23:59:59.000Z

268

Modlisation numrique par la mthode SPH de la sparation eau-huile dans les sparateurs gravitaires.  

E-Print Network (OSTI)

??Dans l'industrie d'extraction ptrolire, l'efficacit des sparateurs eau-huile pour la production offshore est cruciale. L'objet de ce travail est de mettre en place les outils (more)

Grenier, Nicolas

2009-01-01T23:59:59.000Z

269

Avestar - Simulators  

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

Meet Our Partners Simulators IGCC Gasification Combined Cycle NGCC SCOT Oxy-coal Shale Gas 3D Virtual IGCC Training How to Register for Training IGCC Gasification Combined...

270

Algorithmes hybrides pour la gestion intelligente de l'nergie dans les smart grids  

E-Print Network (OSTI)

Algorithmes hybrides pour la gestion intelligente de l'énergie dans les smart grids Robin ROCHE1 électrique plus intelligent, dit smart grid. Les travaux présentés dans cet article proposent un système de l'on nomme "smart grid", ou réseau électrique intelligent (Simoes et al., 2011) (voir figure 1

Paris-Sud XI, Université de

271

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS  

SciTech Connect

Work in this quarter focused on the continued running of two SIMVAL cases: {phi} (equivalence ratio) of (1) 0.55 and (2) 0.625. Comparisons were made between RANS and LES predictions for the {phi} of 0.625 case. The LES calculation showed a different flow pattern in the combustor compared to the RANS calculation, in particular the combustor recirculation flow pattern on the centerline is dramatically different. To demonstrate that the LES solution is accurate (and the RANS is not), non-reacting cases based on the Lilley experiment (Lilley, 1985) were run. Results from the Lilley cases verified that the LES calculations more closely match experimental velocity measurements for highly swirled, turbulent flows with a downstream constriction. In particular, RANS predictions show a strong centerline recirculation zone in the combustor, while LES predictions show positive axial velocity on the centerline, and an annular recirculation zone around the centerline. Animation files were also created this quarter, so as to better demonstrate the LES predictions.

Karl V. Meredith; Clifford E. Smith

2004-10-01T23:59:59.000Z

272

Microsoft PowerPoint - ARM-STM-Cheng-poster2007  

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

Multi-scale Modeling Framework (MMF) and Multi-scale Modeling Framework (MMF) and global cloud resolving model (GCRM) will play an important role in addressing important climate issues, such as global warming. The difficulties associated with the parameterization of deep convective clouds can be avoided, but those associated with the parameterization of boundary- layer clouds remains. Low-order turbulence closure (LOC) and third- order turbulence closure (TOC) are extensively used for parameterizations for boundary-layer clouds. Subgrid-scale turbulence transports of scalars are parameterized differently in the two types of closure. 2. Experiment Design The BOMEX and ARM shallow cumulus cases are simulated with System for Atmospheric Modeling (SAM) CRM and the SAM LES (large- eddy simulation) to explore the sensitivity of the

273

ARM - Publications: Science Team Meeting Documents  

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

Solar Radiative Influences on Drop Growth Solar Radiative Influences on Drop Growth Harrington, J.Y, Hartman, C., and Verlinde, J., The Pennsylvania State University Thirteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting The offsetting effects of solar heating and infrared cooling on the vapor-depositional growth of cloud droplets is investigated. In this study, a marine stratocumulus cloud was simulated by using a large eddy simulation (LES) model and a detailed microphysical bin model. Including infrared cooling as well as solar heating had two effects. The first effect is related to the fact that vapor-depositional growth of drops is radius dependent - solar heating effects dominated at larger drop sizes (> 100 microns) and infrared cooling effects dominated at smaller drop sizes

274

Simulation tools  

E-Print Network (OSTI)

In the last two decades, simulation tools made a significant contribution to the great progress in development of power electronics. Time to market was shortened and development costs were reduced drastically. Falling costs, as well as improved speed and precision, opened new fields of application. Today, continuous and switched circuits can be mixed. A comfortable number of powerful simulation tools is available. The users have to choose the best suitable for their application. Here a simple rule applies: The best available simulation tool is the tool the user is already used to (provided, it can solve the task). Abilities, speed, user friendliness and other features are continuously being improvedeven though they are already powerful and comfortable. This paper aims at giving the reader an insight into the simulation of power electronics. Starting with a short description of the fundamentals of a simulation tool as well as properties of tools, several tools are presented. Starting with simplified models ...

Jenni, F

2006-01-01T23:59:59.000Z

275

Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during SHEBA/FIRE-ACE  

SciTech Connect

An intercomparison of six cloud-resolving and large-eddy simulation models is presented. This case study is based on observations of a persistent mixed-phase boundary layer cloud gathered on 7 May, 1998 from the Surface Heat Budget of Arctic Ocean (SHEBA) and First ISCCP Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). Ice nucleation is constrained in the simulations in a way that holds the ice crystal concentration approximately fixed, with two sets of sensitivity runs in addition to the baseline simulations utilizing different specified ice nucleus (IN) concentrations. All of the baseline and sensitivity simulations group into two distinct quasi-steady states associated with either persistent mixed-phase clouds or all-ice clouds after the first few hours of integration, implying the existence of multiple equilibria. These two states are associated with distinctly different microphysical, thermodynamic, and radiative characteristics. Most but not all of the models produce a persistent mixed-phase cloud qualitatively similar to observations using the baseline IN/crystal concentration, while small increases in the IN/crystal concentration generally lead to rapid glaciation and conversion to the all-ice state. Budget analysis indicates that larger ice deposition rates associated with increased IN/crystal concentrations have a limited direct impact on dissipation of liquid in these simulations. However, the impact of increased ice deposition is greatly enhanced by several interaction pathways that lead to an increased surface precipitation flux, weaker cloud top radiative cooling and cloud dynamics, and reduced vertical mixing, promoting rapid glaciation of the mixed-phase cloud for deposition rates in the cloud layer greater than about 1-2x10-5 g kg-1 s-1. These results indicate the critical importance of precipitation-radiative-dynamical interactions in simulating cloud phase, which have been neglected in previous fixed-dynamical parcel studies of the cloud phase parameter space. Large sensitivity to the IN/crystal concentration also suggests the need for improved understanding of ice nucleation and its parameterization in models.

Morrison, H.; Zuidema, Paquita; Ackerman, Andrew; Avramov, Alexander; de Boer, Gijs; Fan, Jiwen; Fridlind, Ann; Hashino, Tempei; Harrington, Jerry Y.; Luo, Yali; Ovchinnikov, Mikhail; Shipway, Ben

2011-06-16T23:59:59.000Z

276

Problmes et mthodes en toponymie franaise : essais de linguistique historique sur les noms de lieux du Roannais.  

E-Print Network (OSTI)

??Le prsent travail vise dresser un bilan critique des travaux de toponymie franaise et formuler les principes dune science des noms de lieux (more)

Gouvert, Xavier

2008-01-01T23:59:59.000Z

277

Simulation: Thermodynamic  

E-Print Network (OSTI)

(by selectively reflecting), so system energy stays constant. -- Heat is generated by viscous action corresponds to vortex generation in similar fluid mechanical situations. But the high flow speed#12; ' & $ % Coupling Continuum to Molecular Dynamics Simulation: Reflecting Particle Method

Li, Ju

278

Dynamic Models for the Subgrid-Scale Mixing of Reactants in Atmospheric Turbulent Reacting Flows  

Science Conference Proceedings (OSTI)

The effects of the subgrid scales on chemical transformations in large-eddy simulations of the convective atmospheric boundary layer (CBL) are investigated. Dynamic similarity subgrid-scale models are formulated and used to calculate the subgrid-...

Jean-Franois Vinuesa; Fernando Port-Agel

2008-05-01T23:59:59.000Z

279

Composite Structure of Plumes in Stratus-topped Boundary Layers  

Science Conference Proceedings (OSTI)

Knowledge of convective plumes within the clear convective boundary layer (CBL) is quite advanced owing to direct measurements, tank experiments, and large-eddy simulation studies. As a result, modeling of the CBL is relatively successful. ...

Chin-Hoh Moeng; Ulrich Schumann

1991-10-01T23:59:59.000Z

280

Mixing in Shallow Cumulus Clouds Studied by Lagrangian Particle Tracking  

Science Conference Proceedings (OSTI)

Mixing between shallow cumulus clouds and their environment is studied using large-eddy simulations. The origin of in-cloud air is studied by two distinct methods: 1) by analyzing conserved variable mixing diagrams (Paluch diagrams) and 2) by ...

Thijs Heus; Gertjan van Dijk; Harm J. J. Jonker; Harry E. A. Van den Akker

2008-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "large-eddy simulation les" 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.
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to obtain the most current and comprehensive results.


281

Effect of Aerosol on the Susceptibility and Efficiency of Precipitation in Warm Trade Cumulus Clouds  

Science Conference Proceedings (OSTI)

Large-eddy simulations of warm, trade wind cumulus clouds are conducted for a range of aerosol conditions with a focus on precipitating clouds. Individual clouds are tracked over the course of their lifetimes. Precipitation rate decreases ...

Hongli Jiang; Graham Feingold; Armin Sorooshian

2010-11-01T23:59:59.000Z

282

NERSC-ScienceHighlightsDecember2011.pptx  

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

cars. (D. Mei, PNNL, L-W. Wang, LBNL) Energy NERSC resources were used to model a real coal gasifier with a Large Eddy Simulation code. (P. Smith, U. Utah) Climate New techniques...

283

The Sensitivity of Springtime Arctic Mixed-Phase Stratocumulus Clouds to Surface Layer and Cloud-Top Inversion Layer Moisture Sources  

Science Conference Proceedings (OSTI)

In this study a series of idealized large eddy simulations is used to understand the relative impact of cloud top and subcloud layer sources of moisture on the microphysical-radiative-dynamical feedbacks in an Arctic mixed-phase stratocumulus (...

Amy Solomon; Matthew D. Shupe; Ola Persson; Hugh Morrison; Takanobu Yamaguchi; Peter M. Caldwell; Gijs de Boer

284

The Influence of Entrainment and Mixing Assumption on AerosolCloud Interactions in Marine Stratocumulus  

Science Conference Proceedings (OSTI)

This study uses large-eddy simulation with bin microphysics to investigate the influence of entrainment and mixing on aerosolcloud interactions in the context of idealized, nocturnal, nondrizzling marine stratocumulus (Sc). Of particular ...

Adrian A. Hill; Graham Feingold; Hongli Jiang

2009-05-01T23:59:59.000Z

285

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

286

WaveTurbulence Interactions in a Breaking Mountain Wave  

Science Conference Proceedings (OSTI)

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

Craig C. Epifanio; Tingting Qian

2008-10-01T23:59:59.000Z

287

Single-Point Closures in a Neutrally Stratified Boundary Layer  

Science Conference Proceedings (OSTI)

Closure assumptions often employed in single-point closure models for boundary-layer applications are evaluated against a neutrally stratified planetary boundary-layer flow generated by large-eddy simulation. The contributions from slow and rapid ...

Anders Andrn; Chin-Hoh Moeng

1993-10-01T23:59:59.000Z

288

Numerical Study of Penetrative and Solid Lid Nonpenetrative Convective Boundary Layers  

Science Conference Proceedings (OSTI)

A large eddy simulation model was used to generate and compare statistics of turbulence during nonpenetrative and penetrative dry convection. In penetrative convection dimensionless vertical velocities in updrafts were found to have almost the ...

Zbigniew Sorbjan

1996-01-01T23:59:59.000Z

289

Daytime Heat Transfer Processes Related to Slope Flows and Turbulent Convection in an Idealized Mountain Valley  

Science Conference Proceedings (OSTI)

The mechanisms governing the daytime development of thermally driven circulations along the transverse axis of idealized two-dimensional valleys are investigated by means of large-eddy simulations. In particular, the impact of slope winds and ...

Stefano Serafin; Dino Zardi

2010-11-01T23:59:59.000Z

290

Daytime heat transfer processes over mountainous terrain  

Science Conference Proceedings (OSTI)

The daytime heat transfer mechanisms over mountainous terrain are investigated by means of large-eddy simulations over idealized valleys. Two- and three-dimensional topographies, corresponding to infinite and finite valleys, are used in order to ...

Juerg Schmidli

291

Surface energy balance and buoyancy response to shallow cumulus shading  

Science Conference Proceedings (OSTI)

The interactions surrounding the coupling between surface energy balance and a boundary layer with shallow cumuli are investigated using the National Center for Atmospheric Researchs large eddy simulation code coupled to the NOAH land surface ...

Fabienne Lohou; Edward G. Patton

292

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

Science Conference Proceedings (OSTI)

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

Nobuhiro Suzuki; Tetsu Hara; Peter P. Sullivan

2013-02-01T23:59:59.000Z

293

Scalar Turbulence in Convective Boundary Layers by Changing the Entrainment Flux  

Science Conference Proceedings (OSTI)

A large-eddy simulation model is adopted to investigate the evolution of scalars transported by atmospheric cloud-free convective boundary layer flows. Temperature fluctuations due to the ground release of sensible heat and concentration ...

Alessandra S. Lanotte; Irene M. Mazzitelli

2013-01-01T23:59:59.000Z

294

Radiative Impacts of Free-Tropospheric Clouds on the Properties of Marine Stratocumulus  

Science Conference Proceedings (OSTI)

Observations from multiple satellites and large-eddy simulations (LESs) from the Regional Atmospheric Modeling System (RAMS) are used to determine the extent to which free-tropospheric clouds (FTCs) affect the properties of stratocumulus. ...

Matthew W. Christensen; Gustavo G. Carri; Graeme L. Stephens; William R. Cotton

2013-10-01T23:59:59.000Z

295

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

Science Conference Proceedings (OSTI)

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

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

1998-08-01T23:59:59.000Z

296

An Analytic Longwave Radiation Formula for Liquid Layer Clouds  

Science Conference Proceedings (OSTI)

Many Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) intercomparisons of boundary layer clouds have used a convenient but idealized longwave radiation formula for clouds in their large-eddy simulations (LESs). Under ...

Vincent E. Larson; Kurt E. Kotenberg; Norman B. Wood

2007-02-01T23:59:59.000Z

297

Impact of Gravity Waves on Marine Stratocumulus Variability  

Science Conference Proceedings (OSTI)

The impact of gravity waves on marine stratocumulus is investigated using a large-eddy simulation model initialized with sounding profiles composited from the Variability of American Monsoon Systems (VAMOS) OceanCloudAtmosphereLand Study ...

Qingfang Jiang; Shouping Wang

2012-12-01T23:59:59.000Z

298

Evaluating Weather Research and Forecasting (WRF) Model Predictions of Turbulent Flow Parameters in a Dry Convective Boundary Layer  

Science Conference Proceedings (OSTI)

Weather Research and Forecasting (WRF) model predictions using different boundary layer schemes and horizontal grid spacings were compared with observational and numerical large-eddy simulation data for conditions corresponding to a dry ...

Jeremy A. Gibbs; Evgeni Fedorovich; Alexander M. J. van Eijk

2011-12-01T23:59:59.000Z

299

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

300

The Decay of Convective Turbulence  

Science Conference Proceedings (OSTI)

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

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

1986-03-01T23:59:59.000Z

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

Entrainment Rate, Cloud Fraction, and Liquid Water Path of PBL Stratocumulus Clouds  

Science Conference Proceedings (OSTI)

The large eddy simulation technique is used to search for key factors in determining the entrainment rate, cloud fraction, and liquid water path in the stratocumulus-topped boundary layer (STBL), with the goal of developing simple schemes of ...

Chin-Hoh Moeng

2000-11-01T23:59:59.000Z

302

Measurement of Convective Entrainment Using Lagrangian Particles  

Science Conference Proceedings (OSTI)

Lagrangian particle tracking is used in a large-eddy simulation to study an individual cumulus congestus. This allows for the direct measurement of the convective entrainment rate and of the residence times of entrained parcels within the cloud. ...

Kyongmin Yeo; David M. Romps

2013-01-01T23:59:59.000Z

303

Experimental and Numerical Study of the Turbulence Characteristics of Airflow around a Research Vessel  

Science Conference Proceedings (OSTI)

Airflow distortion by research vessels has been shown to significantly affect micrometeorological measurements. This study uses an efficient time-dependent large-eddy simulation numerical technique to investigate the effect of the R/V Tangaroa on ...

Stphane Popinet; Murray Smith; Craig Stevens

2004-10-01T23:59:59.000Z

304

Stratification Effects in a Bottom Ekman Layer  

Science Conference Proceedings (OSTI)

A stratified bottom Ekman layer over a nonsloping, rough surface is studied using a three-dimensional unsteady large eddy simulation to examine the effects of an outer layer stratification on the boundary layer structure. When the flow field is ...

John R. Taylor; Sutanu Sarkar

2008-11-01T23:59:59.000Z

305

Posters  

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

1 1 Posters Development of a Scheme for Parameterizing the Effects of Cloud Condensation Nuclei on Stratocumulus Cloud Albedo W. R. Cotton, B. Stevens, D. Duda, and G. L. Stephens Colorado State University Department of Atmospheric Science Fort Collins, Colorado * Drizzle formation is a complicated function of the CCN spectra, especially giant and ultra-giant aerosol, cloud liquid water contents, mixing processes, and the time scales of cloud drafts which are determined by the strengths and depths of cloud drafts. Approach Our approach is to produce large eddy simulations (LES) or cloud-resolving models (CRMs) of marine stratocumulus clouds including the use of bin-resolving aerosol and cloud microphysics. The model is designed to obtain an internally consistent coupling between stratocumulus cloud dynamics

306

X:\ARM_19~1\P225-243.WPD  

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

5 5 Development and Testing of an Aerosol-Stratus Cloud Parameterization Scheme for Middle and High Latitudes P. Q. Olsson, M. P. Meyers, S. Kreidenweis, and W. R. Cotton Department of Atmospheric Science Colorado State University Fort Collins, Colorado Introduction The aim of this new project is to develop an aerosol/cloud microphysics parameterization of mixed-phase stratus and boundary layer clouds. Our approach is to create, test, and implement a bulk-microphysics/aerosol model using data from Atmospheric Radiation Measurement (ARM) Cloud and Radiation Testbed (CART) sites and large-eddy simulation (LES) explicit bin-resolving aerosol/micro- physics models. The primary objectives of this work are twofold. First, we need the prediction of number con- centrations of activated aerosol which are transferred to the

307

1  

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

Factors Controlling the Properties of Multi-Phase Factors Controlling the Properties of Multi-Phase Arctic Stratocumulus Clouds A. Fridlind and A. Ackerman National Aeronautics and Space Administration - Ames Research Center Moffett Field, California S. Menon and I. Sednev Lawrence Berkeley National Laboratory Berkeley, California Introduction The October 2004 Multi-Phase Arctic Cloud Experiment (M-PACE) Intensive Operational Period (IOP) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility's (ACRF's) North Slope of Alaska (NSA) locale focused on measuring the properties of autumn transition-season arctic stratus and the environmental conditions controlling them, including concentrations of heterogeneous ice nuclei. Our work aims to use a large-eddy simulation (LES) code with embedded size-resolved cloud

308

ARM - Publications: Science Team Meeting Documents  

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

A Satellite Cloud, Radiation and Precipitation Data Set for Cloud Model A Satellite Cloud, Radiation and Precipitation Data Set for Cloud Model Evaluation Xu, K.-M.(a), Wielicki, B.A.(a), Wong, T.(a), and Randall, D.A.(b), NASA Langley Research Center (a), Colorado State University (b) Thirteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting To systematically evaluate cloud models including large-eddy simulation (LES), cloud-resolving models (CRMs), cloud parameterizations in general circulation models (GCMs), one needs a large set of cloud, radiation and precipitation data that are matched with simultaneous atmospheric state data. We have been using a technique to produce such a data set at the NASA Langley Research Center. Specifically, this technique classifies EOS (Earth Observing System) satellite data into distinct cloud systems or "cloud

309

1  

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

Improving the Representation of Aerosol-Cloud- Improving the Representation of Aerosol-Cloud- Precipitation Interactions in Numerical Models D.B. Mechem and Y.L. Kogan Cooperative Institute for Mesoscale Meteorological Studies University of Oklahoma Norman, Oklahoma Introduction Accurately representing aerosol indirect effects in large-scale numerical models requires microphysical parameterizations that treat complex aerosol-cloud-precipitation interactions in a realistic manner. Here we address two important aspects of these microphysical interactions: 1. Development of a new parameterization of giant cloud condensation nuclei (CCN) for use in bulk microphysical models; 2. Aspects of droplet nucleation revealed by 3D large eddy simulation (LES) results but not captured by nucleation schemes based on simple empirical relations or 1D parcel models

310

Categorical Exclusion Determinations: National Energy Technology Laboratory  

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

September 18, 2013 September 18, 2013 CX-010933: Categorical Exclusion Determination High Energy Density Lithium (Li)-ion Cells for Electric Vehicles (EV) Based on Novel, High Voltage Cathode Material Systems CX(s) Applied: B3.6 Date: 09/18/2013 Location(s): California Offices(s): National Energy Technology Laboratory September 18, 2013 CX-010932: Categorical Exclusion Determination High Energy Density Lithium (Li)-ion Cells for Electric Vehicles (EV) Based on Novel, High Voltage Cathode Material Systems CX(s) Applied: B3.6 Date: 09/18/2013 Location(s): California Offices(s): National Energy Technology Laboratory August 23, 2013 CX-010779: Categorical Exclusion Determination Predictive Large Eddy Simulation (LES) Modeling and Validation for High-Pressure Turbulent Flames and Flashback in Hydrogen-Enriched Gas

311

Page not found | Department of Energy  

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

21 - 13630 of 26,764 results. 21 - 13630 of 26,764 results. Download CX-010778: Categorical Exclusion Determination Technology Integration Program CX(s) Applied: A9, A11 Date: 08/23/2013 Location(s): Oklahoma Offices(s): National Energy Technology Laboratory http://energy.gov/nepa/downloads/cx-010778-categorical-exclusion-determination Download CX-010779: Categorical Exclusion Determination Predictive Large Eddy Simulation (LES) Modeling and Validation for High-Pressure Turbulent Flames and Flashback in Hydrogen-Enriched Gas Turbine CX(s) Applied: A9, B3.6 Date: 08/23/2013 Location(s): Texas Offices(s): National Energy Technology Laboratory http://energy.gov/nepa/downloads/cx-010779-categorical-exclusion-determination Download CX-010780: Categorical Exclusion Determination Advanced Analytical Methods for Air and Stray Gas Emissions and Produced

312

Modeling Turbulent Flow  

National Nuclear Security Administration (NNSA)

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

313

Research Highlight  

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

Measurement of Convective Entrainment Using Lagrangian Particles Measurement of Convective Entrainment Using Lagrangian Particles Download a printable PDF Submitter: Romps, D., University of California, Berkeley Area of Research: Cloud Processes Working Group(s): Cloud Life Cycle Journal Reference: Yeo K and DM Romps. 2013. "Measurement of convective entrainment using Lagrangian particles." Journal of the Atmospheric Sciences, 70(1), doi:10.1175/JAS-D-12-0144.1. Trajectories of seven particles that are entrained at the cloud base and transported to the cloud top. Colors denote the mixing ratio of condensed water. Previous work by Romps (2010) found large entrainment rates of ~100% per kilometer for deep convection using a new technique for large-eddy simulations (LES) called "Eulerian direct measurement". These results

314

L'opration populaire d'amnagement de Pointe-Saint-Charles : vers une appropriation du quartier par les citoyens sous l'initiative de la table de concertation action-gardien?.  

E-Print Network (OSTI)

??Dans le contexte de mtropolisation, les grands projets de dveloppement urbains se sont imposs comme une stratgie de revitalisation urbaine privilgie pour positionner les villes (more)

Grenier, Genevive

2009-01-01T23:59:59.000Z

315

Approche mthodologique de l'impact de l'environnement radiatif spatial sur les proprits intrinsques d'une diode laser.  

E-Print Network (OSTI)

??L'interaction rayonnement matire est bien connue et documente. A contrario, les tudes portant sur l'influence d'un environnement radiatif sur les diodes laser sont rares, et (more)

Boutillier, Mathieu

2007-01-01T23:59:59.000Z

316

L'EXISTENCE DES LOIS : LES POUVOIRS CAUSAUX DANS LA NATURE Anjan Chakravartty  

E-Print Network (OSTI)

discours d'une manière purement linguistique (par opposition à une interprétation les prédicats. Par conséquent, nous devons distinguer une acceptation linguistique dispositif linguistique mais qu'il comporte une réelle signification ontologique

Chakravartty, Anjan

317

3D multi-scale scanning of the archaeological cave "les Fraux" in (France)  

Science Conference Proceedings (OSTI)

The archaeological cave Les Fraux (Saint-Martin-de-Fressengeas, Dordogne) forms a great network of galleries, characterized by the exceptional richness of its archaeological Bronze Age remains such as domestic fireplaces, ceramic and metal ... Keywords: PDF-3D, archaeology, bronze age, cave, close range, documentation, dordogne-france, high resolution, photogrammetry, scanarm, terrestrial laser scanner (TLS)

Pierre Grussenmeyer; Albane Burens; Emmanuel Moisan; Samuel Guillemin; Laurent Carozza; Raphalle Bourrillon; Stphane Petrognani

2012-10-01T23:59:59.000Z

318

Un nouveau TCL pour les oprateurs de covariance dans le modle ARH(1).  

E-Print Network (OSTI)

Un nouveau TCL pour les opérateurs de covariance dans le modèle ARH(1). André MAS Université, nous donnons des conditions su¢ santes pour l'obtention du TCL pour la suite des opérateurs de

Mas, André

319

LES of an ignition sequence in a gas turbine M. Boileau a,, G. Staffelbach a  

E-Print Network (OSTI)

LES of an ignition sequence in a gas turbine engine M. Boileau a,, G. Staffelbach a , B. CuenotTurbomeca (SAFRAN group), Bordes, France Abstract Being able to ignite or reignite a gas turbine engine in a cold including 18 burners. This geometry corresponds to a real gas turbine chamber. Massively parallel computing

320

Digestion Simulations  

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

Digestion Simulations Digestion Simulations Name: Lisa Location: N/A Country: N/A Date: N/A Question: My 5th grade students are beginning an experiment next week and their hypothesis involves edibility(edibleness?). Is there a way to replicate the stomach in, say, a bottle?? Are there ways to test for edibleness(?) without actually ingesting the experiment yourself? Replies: I would not recommend the idea of a bottle stomach. The stomach digests only proteins anyway with HCl [pH 1.0] which is very, very strong acid that will burn seriously if in contact with skin. The intestine is just as much responsible for digestion of lipids [bile], carbohydrates and remaining proteins using enzymes, many of these you do not want to be handling, let alone purchase. As a high school teacher, I have lab exercises dealing with digestion, but I can not recommend any of these unless you are set up with a functional science laboratory and all the safety equipment necessary.

Note: This page contains sample records for the topic "large-eddy simulation les" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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321

La vengeance du consommateur insatisfait sur Internet et l'effet sur les attitudes des autres consommateurs.  

E-Print Network (OSTI)

??Ce travail doctoral s'intresse au phnomne de vengeance du consommateur insatisfait sur Internet et l'effet de cette action sur les attitudes des autres consommateurs. Deux (more)

Passos, Gisle

2013-01-01T23:59:59.000Z

322

Influence de l'utilisation du biocarburant E85 sur les missions polluantes d'un vhicule hybride lectrique.  

E-Print Network (OSTI)

??Il est ncessaire de rduire les missions polluantes des vhicules moteurs thermiques. L'utilisation de vhicules hybrides lectriques d'une part, ainsi que la combustion de (more)

Terrier, Philippe

2005-01-01T23:59:59.000Z

323

Caractrisation et modlisation de la prcipitation du carbure de niobium et du cuivre dans les aciers bas carbone.  

E-Print Network (OSTI)

??La prcipitation de NbC dans les aciers bas carbone permet une amlioration consquente des proprits mcaniques. Cependant, aucune caractrisation quantitative dtaille de cette prcipitation n'est (more)

Perrard, Fabien

324

IMITATION, PAR LES COURANTS LIQUIDES OU GAZEUX, DES PHNOMNES D'LECTRICIT ET DE MAGNTISME ;  

E-Print Network (OSTI)

être exposé succinctement. I. - Effets mécaniques. . Hydro-aimant. - Après avoir adapté à un tuyau d'au contact, car le liquide s'écoule au pourtour avec une faible vitesse; mais, si l'onveut soulever le tube'on puisse produire, avec ces deux sortes d'ajutages, des hydro-aimants à deux pôles contraires, l' un

Paris-Sud XI, Université de

325

FUEL-FLEXIBLE GASIFICATION-COMBUSTION TECHNOLOGY FOR PRODUCTION OF H2 AND SEQUESTRATION-READY CO2  

DOE Green Energy (OSTI)

Further development of a combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this sixth quarterly report. CFD Research Corporation (CFDRC) is developing the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. In this quarter, in-situ adaptive tabulation (ISAT) for efficient chemical rate storage and retrieval was implemented and tested within the Linear Eddy Model (LEM). ISAT type 3 is being tested so that extrapolation can be performed and further improve the retrieval rate. Further testing of the LEM for subgrid chemistry was performed for parallel applications and for multi-step chemistry. Validation of the software on backstep and bluff-body reacting cases were performed. Initial calculations of the SimVal experiment at Georgia Tech using their LES code were performed. Georgia Tech continues the effort to parameterize the LEM over composition space so that a neural net can be used efficiently in the combustion LES code. A new and improved Artificial Neural Network (ANN), with log-transformed output, for the 1-step chemistry was implemented in CFDRC's LES code and gave reasonable results. This quarter, the 2nd consortium meeting was held at CFDRC. Next quarter, LES software development and testing will continue. Alpha testing of the code will continue to be performed on cases of interest to the industrial consortium. Optimization of subgrid models will be pursued, particularly with the ISAT approach. Also next quarter, the demonstration of the neural net approach, for multi-step chemical kinetics speed-up in CFD-ACE+, will be accomplished.

George Rizeq; Janice West; Arnaldo Frydman; Raul Subia; Vladimir Zamansky; Tomasz Wiltowski; Tom Miles; Bruce Springsteen

2002-04-30T23:59:59.000Z

326

Evaluation of an LES-Based Wind Profiler Simulator for Observations of a Daytime Atmospheric Convective Boundary Layer  

Science Conference Proceedings (OSTI)

The daytime atmospheric convective boundary layer (CBL) is characterized by strong turbulence that is primarily caused by buoyancy forced from the heated underlying surface. The present study considers a combination of a virtual radar and large ...

Danny E. Scipin; Phillip B. Chilson; Evgeni Fedorovich; Robert D. Palmer

2008-08-01T23:59:59.000Z

327

Parameterization and Analysis of 3-D Solar Radiative Transfer in Clouds: Final Report  

Science Conference Proceedings (OSTI)

This document reports on the research that we have done over the course of our two-year project. The report also covers the research done on this project during a 1 year no-cost extension of the grant. Our work has had two main, inter-related thrusts: The first thrust was to characterize the response of stratocumulus cloud structure and dynamics to systematic changes in cloud infrared radiative cooling and solar heating using one-dimensional radiative transfer models. The second was to couple a three-dimensional (3-D) solar radiative transfer model to the Large Eddy Simulation (LES) model that we use to simulate stratocumulus. The purpose of the studies with 3-D radiative transfer was to examine the possible influences of 3-D photon transport on the structure, evolution, and radiative properties of stratocumulus. While 3-D radiative transport has been examined in static cloud environments, few studies have attempted to examine whether the 3-D nature of radiative absorption and emission influence the structure and evolution of stratocumulus. We undertook this dual approach because only a small number of LES simulations with the 3-D radiative transfer model are possible due to the high computational costs. Consequently, LES simulations with a 1-D radiative transfer solver were used in order to examine the portions of stratocumulus parameter space that may be most sensitive to perturbations in the radiative fields. The goal was then to explore these sensitive regions with LES using full 3-D radiative transfer. Our overall goal was to discover whether 3-D radiative processes alter cloud structure and evolution, and whether this may have any indirect implications for cloud radiative properties. In addition, we collaborated with Dr. Tamas Varni, providing model output fields for his attempt at parameterizing 3-D radiative effects for cloud models.

Jerry Y. Harrington

2012-09-21T23:59:59.000Z

328

Simulation of Storm Occurrences Using Simulated Annealing  

Science Conference Proceedings (OSTI)

Modeling storm occurrences has become a vital part of hurricane prediction. In this paper, a method for simulating event occurrences using a simulated annealing algorithm is described. The method is illustrated using annual counts of hurricanes ...

Ravindra S. Lokupitiya; Leon E. Borgman; Richard Anderson-Sprecher

2005-11-01T23:59:59.000Z

329

valuation de l'impact de la simplification linguistique sur la russite en rsolution de problmes mathmatiques chez les lves d'accueil, allophones et francophones du secondaire.  

E-Print Network (OSTI)

??Lorsque des lves tentent de rsoudre un problme mathmatique crit, il n'est pas rare de les entendre se plaindre de la difficult de la tche. (more)

Frchette, Sonia

2007-01-01T23:59:59.000Z

330

14.12. Ctedra Sampol de Domtica i Eficincia Energtica Les activitats realitzades en el marc de la Ctedra Sampol de Domtica i Eficincia  

E-Print Network (OSTI)

«SmartGrid, cas del ParcBIT i la UIB». Finalment en el marc de les actuacions de recerca que han portat

Oro, Daniel

331

Winter Simulation Conference  

Science Conference Proceedings (OSTI)

Welcome to the 2009 Winter Simulation Conference (WSC), recognized as the premiere international conference for simulation professionals in discrete and combined discrete-continuous simulation. WSC is always located in exciting and dynamic locations ...

Ann Dunkin; Ricki G. Ingalls

2009-12-01T23:59:59.000Z

332

EXPOS ET MISE AU POINT BIBLIOGRAPHIQUE LA FORMATION DES PARTICULES DE CARBONE DANS LES FLAMMES  

E-Print Network (OSTI)

des fours, qu'ils soient aciéristes, verriers, ou cimentiers. On sait que le rayonnement des flammes d'hydro cristaux de noir d'acéty- lène peut être due à la présence d'atomes interstitiels d'hydrogène, car on trouve généralement 1 % d'hydro- gène dans les dépôts de carbone-suie. Pour certains auteurs la structure

Paris-Sud XI, Université de

333

Fire, Smoke, and Simulations  

Science Conference Proceedings (OSTI)

... NIST Technologies Help Improve Homeland Security. AVI file (Smokeview simulation animation). Initial Model for Fires in ...

2010-10-05T23:59:59.000Z

334

Progress in sub-grid scale modeling of shock-turbulence interaction  

DOE Green Energy (OSTI)

The authors report on progress in the development of sub grid scale (SGS) closure relationships for the unresolved motion scales in compressible large eddy simulations (LES). At present they are refining the SGS model and overall LES procedure to include: a linearized viscoelastic model for finite thickness shock distortions and shocked turbulence field response; multiple scale asymptotic considerations to improve predictions of average near-wall surface behavior; and a spectral statistical model simulating the effects of high wave number stochastic feed-back from the unresolved SGS nonlinear motion influences on the explicitly resolved grid scale motions. Predicted amplification levels, modal energy partition, shock translational to turbulence kinetic energy transfer, and viscoelastic spatio-temporal response of turbulence to shock interaction are examined in comparison with available experimental evidence. Supplemental hypersonic compressible turbulence experimental information is developed from sub nanosecond interval pulsed shadowgraph evidence of laser impulse generated hypervelocity shocks interacting with intense, previously developed and carefully characterized initial turbulence. Accurate description of the influence of shock-turbulence interactions is vital for predicting their influence on: Supersonic/hypersonic flow field analysis, aerodynamic design, and aerostructural materials selection. Practical applications also include interior supersonic combustion analysis and combustion chamber design. It is also the essential foundation for accurately predicting the development and evolution of flow-field generated thermal and electromagnetic radiation important to hypersonic flight vehicle survivability, detection and communication.

Buckingham, A.C. [Lawrence Livermore National Lab., CA (United States). Center for Advanced Fluid Dynamics Applications; Grun, J. [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.

1994-12-01T23:59:59.000Z

335

The ATLAS Simulation Infrastructure  

E-Print Network (OSTI)

The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.

The ATLAS Collaboration

2010-05-25T23:59:59.000Z

336

Molecular diffusion effects in LES of a piloted methane-air flame  

SciTech Connect

Molecular diffusion effects in LES of a piloted methane-air (Sandia D) flame are investigated on a series of grids with progressively increased resolution. The reacting density, temperature and chemical composition are modeled based on the mixture fraction approach combined with a steady flamelet model. With a rationale to minimize interpolation uncertainties that are routinely introduced by a flamelet table look-up, quadratic splines relationships are employed to represent thermochemical variables. The role of molecular diffusivity in effecting spatial transport is studied by drawing a comparison with the turbulent diffusivity and analyzing their statistics conditioned on temperature. Statistical results demonstrate that the molecular diffusivity in the near-field almost always exceeds the turbulent diffusivity, except at low temperatures (less than 500 K). Thus, by altering the jet near-field, molecular transport plays an important role in the further downstream jet development. Molecular diffusivity continues to dominate in the centerline region throughout the flow field. Overall, the results suggest the strong necessity to represent molecular transport accurately in LES studies of turbulent reacting flows. (author)

Kemenov, Konstantin A.; Pope, Stephen B. [Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 (United States)

2011-02-15T23:59:59.000Z

337

Travail social et toxicomanie: la pratique des travailleurs sociaux dans le bas seuil ou quelle(s) identit(s) professionnelle(s) dfendent les travailleurs sociaux dans les structures "bas seuil" et quel(s) sens attribuent-ils leur(s) pratiques professionnelles?.  

E-Print Network (OSTI)

??Le thme propos par cette recherche sarticule autour du travail social dans le domaine de la toxicodpendance, notamment dans les lieux de prise en charge (more)

Portillo Clapasson, Maria Jos

1000-01-01T23:59:59.000Z

338

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

339

Planar Richtmyer-Meshkov instabilities and transition to turbulence  

Science Conference Proceedings (OSTI)

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

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

2011-01-21T23:59:59.000Z

340

Delphes, a framework for fast simulation of a generic collider experiment  

E-Print Network (OSTI)

This paper presents a new C++ framework, DELPHES, performing a fast multipurpose detector response simulation. The simulation includes a tracking system, embedded into a magnetic field, calorimeters and a muon system, and possible very forward detectors arranged along the beamline. The framework is interfaced to standard file formats (e.g. Les Houches Event File or HepMC) and outputs observables such as isolated leptons, missing transverse energy and collection of jets which can be used for dedicated analyses. The simulation of the detector response takes into account the effect of magnetic field, the granularity of the calorimeters and subdetector resolutions. A simplified preselection can also be applied on processed events for trigger emulation. Detection of very forward scattered particles relies on the transport in beamlines with the HECTOR software. Finally, the FROG 2D/3D event display is used for visualisation of the collision final states.

S. Ovyn; X. Rouby; V. Lemaitre

2009-03-12T23:59:59.000Z

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

China's Energy Situation and Its Implications in the New by Hengyun Ma, Les Oxley and John Gibson  

E-Print Network (OSTI)

and the energy economy, in particular. Keywords: China; Energy; Fossil fuels; Renewable Energy JEL by an investigation and analysis of China's energy resources, including renewable energy. In the third section we1 China's Energy Situation and Its Implications in the New Millennium by Hengyun Ma, Les Oxley

Hickman, Mark

342

Ad Hoc Distributed Simulations  

Science Conference Proceedings (OSTI)

An ad hoc distributed simulation is a collection of autonomous on-line simulations brought together to model an operational system. They offer the potential of increased accuracy, responsiveness, and robustness compared to centralized approaches. They ...

Richard Fujimoto; Michael Hunter; Jason Sirichoke; Mahesh Palekar; Hoe Kim; Wonho Suh

2007-06-01T23:59:59.000Z

343

Radio Channel Simulator  

Radio Channel Simulator (RCSim) is a simulation package for making site-specific predictions of radio signal strength. The software computes received power atdiscrete grid points as a function of the transmitter location and propagation environment. ...

344

Simulated Chromatographic Data  

Science Conference Proceedings (OSTI)

Simulated Chromatographic Data. Description/Summary: ... Data are provided in individual files that are packaged together in grouped zip files. ...

2012-10-09T23:59:59.000Z

345

Atomistic Simulation and ICME  

Science Conference Proceedings (OSTI)

The annual NIST workshops on "Atomistic Simulations for Industrial Needs" .... First Principles Modeling of Shape Memory Alloy Magnetic Refrigeration Materials.

346

Weld arc simulator  

DOE Patents (OSTI)

An arc voltage simulator for an arc welder permits the welder response to a variation in arc voltage to be standardized. The simulator uses a linear potentiometer connected to the electrode to provide a simulated arc voltage at the electrode that changes as a function of electrode position.

Burr, M.J.

1989-03-01T23:59:59.000Z

347

Les bKa'brgyad - Sources canoniques et tradition de Nyangral Nyima 'od zer  

E-Print Network (OSTI)

la Pense, li la famille du bouddha Ak?obhya (Thugs Mi bskyod pa'i rigs) nomm dPal Heruka snying rje rol pa'i rgyud (?r?-heruka-karu??kr??ita-tantra), tabli par l'?c?rya H??- kara12 , venu de l'Inde de l'est, prs de Zahor (Est du Bengale) (r... mi tra, Pra chen ha ti, Rum bu ghu ya dhe ba, Dha na sang tri, Shan ting ghar ba. 21 'Ju mi pham (s.d., vol. 21 : 15) mentionne galement cette neuvime cassette, dont les autres gter ston qui ont dcouvert des cycles de bKa' brgyad ne parlent pas...

Sampel, Tenzin

2008-01-01T23:59:59.000Z

348

Air Shower Simulations  

SciTech Connect

Air shower simulations are a vital part of the design of air shower experiments and the analysis of their data. We describe the basic features of air showers and explain why numerical simulations are the appropriate approach to model the shower simulation. The CORSIKA program, the standard simulation program in this field, is introduced and its features, performance and limitations are discussed. The basic principles of hadronic interaction models and some gerneral simulation techniques are explained. Also a brief introduction to the installation and use of CORSIKA is given.

Alania, Marco; Gomez, Adolfo V. Chamorro [Centro de Tecnologias de Informacion y Comunicaciones, Universidad Nacional de Ingenieria, Lima (Peru); Araya, Ignacio J. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Av. Vicuna Mackenna 4860, Santiago (Chile); Huerta, Humberto Martinez; Flores, Alejandra Parra [Facultad de Ciencias Fisico Matematicas, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico); Knapp, Johannes [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)

2009-04-30T23:59:59.000Z

349

Combustion Stability in Complex Engineering Flows | Argonne Leadership  

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

Instantaneous contours of temperature from large eddy simulation Instantaneous contours of temperature from large eddy simulation Instantaneous contours of temperature from large eddy simulation of a hypersonic scramjet combustor at Mach 8 flight conditions. Ethylene fuel is introduced through injection ports at the upper left and mixes with air at supersonic speeds. Flow separation and recirculation in the open cavity encourages fuel/air mixing and stable combustion. To maintain hypersonic flight, the fuel must be mixed, ignited, and burned to completion all within a few milliseconds. Cascade Technologies, Inc. Combustion Stability in Complex Engineering Flows PI Name: Lee Shunn PI Email: shunn@cascadetechnologies.com Institution: Cascade Technologies, Inc. Allocation Program: INCITE Allocation Hours at ALCF: 35 Million

350

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

351

An ontology for trajectory simulation  

Science Conference Proceedings (OSTI)

From the concept exploration for a weapon system to training simulators, from hardware-in-the-loop simulators to mission planning tools, trajectory simulations are used throughout the life cycle of a weapon system. A trajectory simulation can be defined ...

Umut Durak; Halit Oguztuzun; S. Kemal Ider

2006-12-01T23:59:59.000Z

352

Power Market Simulation Workshop  

Science Conference Proceedings (OSTI)

EPRI's first seminar on electricity market simulation provided a forum for discussion of potential modifications and applications for this new technology, specifically in the areas of market design and operations. The resounding messages heard from both speakers and participants were as follows: o The use of simulation for electricity markets has the potential to help society avoid devastating costs due to market flaws. o Market simulation can be broadly applied with a diverse set of potential users. o C...

2002-12-30T23:59:59.000Z

353

Mise en vidence de gnes cibles directs communs FLI-1 et SPI-1/PU.1 dans les rythroleucmies de Friend.  

E-Print Network (OSTI)

??Les facteurs de transcription FLI-1 et SPI-1/PU.1 appartiennent la famille ETS et reconnaissent le mme motif sur l'ADN GGAA. Leur activation est observe de (more)

Giraud, Guillaume

2010-01-01T23:59:59.000Z

354

Multi-Hundred Watt Radioisotope Thermoelectric Generator Program, LES 8/9 Program, MJS Program. Bi-monthly progress report, 1 September--31 October 1974  

DOE Green Energy (OSTI)

Significant events, activities and achievements on the MHW LES 8/9 and MJS Programs for the reporting period are reported. Topics discussed include programmatic, safety, systems, isotope heat source, converter, product assurance, acceptance testing, and converter fabrication. (TFD)

Not Available

1974-01-01T23:59:59.000Z

355

Analyse de cycle de vie de la production bovine : exploration de pratiques et de changements de systme pour rduire les impacts environnementaux.  

E-Print Network (OSTI)

??Cette thse porte sur l'tude des impacts environnementaux de systmes de production de bovins. Le premier objectif tait d'analyser et de comparer les impacts environnementaux (more)

Nguyen, Thi Tuyet Hanh

2012-01-01T23:59:59.000Z

356

Etude d'un systme combin de ventilation et de chauffage au bois dans les btiments basse consommation d'nergie.  

E-Print Network (OSTI)

??Ce travail porte sur ltude et le dveloppement dun systme innovant de ventilation et de chauffage au bois dans les habitations basse consommation dnergie, (more)

Peign, Pierre

2012-01-01T23:59:59.000Z

357

Ferrocyanide waste simulant characterization  

Science Conference Proceedings (OSTI)

Ferrocyanide waste simulants were prepared and characterized to help assess safety concerns associated with the ferrocyanide sludges stored in underground single-shell waste tanks at the Hanford Site. Simulants were prepared to represent the variety of ferrocyanide sludges stored in the storage tanks. Physical properties, chemical compositions, and thermodynamic properties of the simulants were determined. The simulants, as produced, were shown to not sustain propagating reactions when subjected to a strong ignition source. Additional testing and evaluations are recommended to assess safety concerns associated with postulated ferrocyanide sludge dry-out and exposure to external ignition sources.

Jeppson, D.W.; Wong, J.J.

1993-01-01T23:59:59.000Z

358

House Simulation Protocols Report  

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

Building America's House Simulation Protocols report is designed to assist researchers in tracking the progress of multiyear, whole-building energy reduction against research goals for new and...

359

Dynamic Infrared Simulation.  

E-Print Network (OSTI)

?? The increased usage of infrared sensors by pilots has created a growing demand for simulated environments based on infrared radiation. This has led to (more)

Dehlin, Jonas

2006-01-01T23:59:59.000Z

360

A Molecular Simulation Study  

Science Conference Proceedings (OSTI)

Presentation Title, Enhanced CO2 Adsorption in Ti-exchanged Zirconium Organic Frameworks A Molecular Simulation Study. Author(s), Ravichandar Babarao...

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

AVESTAR - Gasification Dynamic Simulator  

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

Meet Our Partners Simulators IGCC Gasification Combined Cycle NGCC SCOT Oxy-coal Shale Gas 3D Virtual IGCC Training How to Register for Training IGCC Gasification Combined...

362

Congrs des innovations mcaniques CIM'08 28-29 avril 2008 Sousse Tunisie. Pilotage des processus collaboratifs dans les  

E-Print Network (OSTI)

1er Congrès des innovations mécaniques CIM'08 ­ 28-29 avril 2008 Sousse ­ Tunisie. Pilotage des Manuscrit auteur, publié dans "1er Congrès des innovations mécaniques CIM'08, Sousse : Tunisie (2008)" #12;CIM'08 ­ 28-29 avril 2008 Sousse ­ Tunisie. 2 1. Introduction Les systèmes PLM sont des systèmes d

Paris-Sud XI, Université de

363

Radiation detector spectrum simulator  

SciTech Connect

A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

Wolf, Michael A. (Los Alamos, NM); Crowell, John M. (Los Alamos, NM)

1987-01-01T23:59:59.000Z

364

Radiation detector spectrum simulator  

DOE Patents (OSTI)

A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

Wolf, M.A.; Crowell, J.M.

1985-04-09T23:59:59.000Z

365

Energetics of Marine Turbine Arrays - Extraction, Dissipation and Diminution  

E-Print Network (OSTI)

A two-scale modelling approach is discussed to predict the performance and energetics of a large number (more than a few hundred) of marine turbines installed as a power farm in a general coastal environment. The kernel of this approach is that the outer (coastal-scale) model/simulation is to assess the reduction of flow passing through a given farm area as a function of the increase of head loss across the farm, whereas the inner (device-scale) model/simulation uses this function to account for the (otherwise unknown) effect of coastal dynamics for that farm site. Large-eddy simulations (LES) of periodic open channel flow (with a porous plate model representing turbines) are then presented as the device-scale part of such a two-scale model of large marine turbine arrays. Results demonstrate how the energetics of turbine arrays (i.e. extraction, dissipation and diminution of energy in the entire farm area) may change depending on the characteristics of the farm site, array configuration and operating conditio...

Nishino, Takafumi

2013-01-01T23:59:59.000Z

366

Combustion and Flame 142 (2005) 329347 www.elsevier.com/locate/combustflame  

E-Print Network (OSTI)

Combustion and Flame 142 (2005) 329­347 www.elsevier.com/locate/combustflame Large-eddy simulation to generate optimized clustering for variable density combustion simulations. A methane­hydrogen fuel algorithms and subfilter models. The combustion chemistry is described using a precomputed, laminar flamelet

Raman, Venkat

367

A Mixed Scheme for Subgrid-Scale Fluxes in Cloud-Resolving Models  

Science Conference Proceedings (OSTI)

A large-domain large-eddy simulation of a tropical deep convection system is used as a benchmark to derive and test a mixed subgrid-scale (SGS) scheme for scalar and momentum fluxes in cloud-resolving models (CRMs). The benchmark simulation ...

C.-H. Moeng; P. P. Sullivan; M. F. Khairoutdinov; D. A. Randall

2010-11-01T23:59:59.000Z

368

Modeling aerosol growth by aqueous chemistry in nonprecipitating stratiform cloud  

SciTech Connect

A new microphysics module based on a two-dimensional (2D) joint size distribution function representing both interstitial and cloud particles is developed and applied to studying aerosol processing in non-precipitating stratocumulus clouds. The module is implemented in a three-dimensional dynamical framework of a large-eddy simulation (LES) model and in a trajectory ensemble model (TEM). Both models are used to study the modification of sulfate aerosol by the activation - aqueous chemistry - resuspension cycle in shallow marine stratocumulus clouds. The effect of particle mixing and different size-distribution representations on modeled aerosol processing are studied in a comparison of the LES and TEM simulations with the identical microphysics treatment exposes and a comparison of TEM simulations with a 2D fixed and moving bin microphysics. Particle mixing which is represented in LES and neglected in the TEM leads to the mean relative per particle dry mass change in the TEM simulations being about 30% lower than in analogous subsample of LES domain. Particles in the final LES spectrum are mixed in from different parcels, some of which have experienced longer in-cloud residence times than the TEM parcels, all of which originated in the subcloud layer, have. The mean relative per particle dry mass change differs by 14% between TEM simulations with fixed and moving bin microphysics. Finally, the TEM model with the moving bin microphysics is used to evaluate assumptions about liquid water mass partitioning among activated cloud condensation nuclei (CCN) of different dry sizes. These assumptions are used in large-scale models to map the bulk aqueous chemistry sulfate production, which is largely proportional to the liquid water mass, to the changes in aerosol size distribution. It is shown that the commonly used assumptions that the droplet mass is independent of CCN size or that the droplet mass is proportional to the CCN size to the third power do not perform well in the considered case. The explicitly predicted water partitioning indicates that the mean mass of droplets participating in the models aqueous chemistry calculations is proportional to the dry CCN size.

Ovchinnikov, Mikhail; Easter, Richard C.

2010-07-29T23:59:59.000Z

369

Modeling & Simulation publications  

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

Modeling & Simulation » Modeling & Simulation » Modeling & Simulation Publications Modeling & Simulation publications Research into alternative forms of energy, especially energy security, is one of the major national security imperatives of this century. Get Expertise David Harradine Physical Chemistry and Applied Spectroscopy Email Josh Smith Chemistry Email The inherent knowledge of transformation has beguiled sorcerers and scientists alike. D.A. Horner, F. Lambert, J.D. Kress, and L.A. Collins, "Transport properties of lithium hydride from quantum molecular dynamics and orbital-free molecular dynamics," Physical Review B - Condensed Matter and Materials Physics 80(2) (2009). J.D. Kress, D.A. Horner, and L.A. Collins, "Mixing rules for optical and transport properties of warm, dense matter," AIP Conference Proceedings 1195, 931-934 (2009).

370

Simulations and symbolic explanations  

Science Conference Proceedings (OSTI)

The following paper defines the problem of writing symbolic explanation facilities for computer simulations. Our approach towards this problem draws from an existing body of research on a related problem, that of writing an explanation facility for an ...

D H Helman; J L Bennett; A W Foster

1986-12-01T23:59:59.000Z

371

The Sky Simulator  

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

framework. The sun is simulated with a 1,000-watt halogen lamp inside a parabolic mirror dish mounted on a track. It can assume any altitude angle from the horizon to the zenith....

372

Escorted free energy simulations  

Science Conference Proceedings (OSTI)

We describe a strategy to improve the efficiency of free energy estimates by reducing dissipation in nonequilibrium Monte Carlo simulations. This strategy generalizes the targeted free energyperturbation approach [C. Jarzynski

Suriyanarayanan Vaikuntanathan; Christopher Jarzynski

2011-01-01T23:59:59.000Z

373

Image simulation using LOCUS  

SciTech Connect

The LOCUS data base program has been used to simulate images and to solve simple equations. This has been accomplished by making each record (which normally would represent a data entry)represent sequenced or random number pairs.

Strachan, J.D.; Roberts, J.A.

1989-09-01T23:59:59.000Z

374

Geology and Reservoir Simulation  

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

Service: 1-800-553-7681 Geology and Reservoir Simulation Background Natural gas from shale is becoming ever more recognized as an abundant and economically viable fuel in the...

375

Theory Modeling and Simulation  

SciTech Connect

Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.

Shlachter, Jack [Los Alamos National Laboratory

2012-08-23T23:59:59.000Z

376

Xyce parallel electronic simulator.  

Science Conference Proceedings (OSTI)

This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide.

Keiter, Eric Richard; Mei, Ting; Russo, Thomas V.; Rankin, Eric Lamont; Schiek, Richard Louis; Thornquist, Heidi K.; Fixel, Deborah A.; Coffey, Todd Stirling; Pawlowski, Roger Patrick; Santarelli, Keith R.

2010-05-01T23:59:59.000Z

377

Applications of HRSG Simulation  

E-Print Network (OSTI)

Heat Recovery Steam Generators are widely used in cogeneration and combined cycle plants generating steam utilizing energy from gas turbine exhaust. Before planning cogen projects, consultants should study various options available in terms of steam parameters and select the optimum. Simulation helps plan such studies. In addition, useful "what if" studies can be performed without even designing the HRSG, thus saving valuable time. This article outlines the applications of HRSG simulation and how plant engineers, consultants can benefit from such studies.

Ganapathy, V. V.

1995-04-01T23:59:59.000Z

378

Computer simulation | Open Energy Information  

Open Energy Info (EERE)

2013 DOI Not Provided Check for DOI availability: http:crossref.org Online Internet link for Computer simulation Citation wikipedia. Computer simulation Internet....

379

High Performance Computing: Modeling & Simulation  

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

High Performance Computing: Modeling & Simulation High Performance Computing: Modeling & Simulation Express Licensing Adaptive Real-Time Methodology for Optimizing Energy-Efficient...

380

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

E-Print Network (OSTI)

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

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

2013-01-01T23:59:59.000Z

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

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

DOE Green Energy (OSTI)

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

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

2007-10-01T23:59:59.000Z

382

Computers in teaching science: To simulate or not to simulate?  

Science Conference Proceedings (OSTI)

Do computer simulations help students learn science? How can we tell? Are there negative implications of using simulations to teach students about real world phenomena? In this paper I describe my experience using a computer simulation on air resistance. In order to parse out the effects of using the computer simulation and of having an interactive learning environment

Richard N. Steinberg

2000-01-01T23:59:59.000Z

383

Computers in teaching science: To simulate or not to simulate?  

E-Print Network (OSTI)

Computers in teaching science: To simulate or not to simulate? Richard N. Steinberg City College of New York Phys. Ed. Res. Suppl. to Am. J. Phys. 68, S37-S41 (2000) Do computer simulations help students about real world phenomena? In this paper I describe my experience using a computer simulation

Steinberg, Richard N.

384

New Physics at the LHC: A Les Houches Report. Physics at Tev Colliders 2007 - New Physics Working Group  

SciTech Connect

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. The signatures are organized according to the experimental objects that appear in the final state, and in particular the number of high p{sub T} leptons. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 11-29 June, 2007).

Brooijmans, Gustaaf H.; /Columbia U.; Delgado, A.; /Notre Dame U.; Dobrescu, Bogdan A.; /Fermilab; Grojean, C.; /CERN /Saclay, SPhT; Narain, Meenakshi; /Brown U.; Alwall, Johan; /SLAC; Azuelos, Georges; /Montreal U. /TRIUMF; Black, K.; /Harvard U.; Boos, E.; /SINP, Moscow; Bose, Tulika; /Brown U.; Bunichev, V.; /SINP, Moscow; Chivukula, R.S.; /Michigan State U.; Contino, R.; /CERN; Djouadi, A.; /Louis Pasteur U., Strasbourg I /Orsay, LAL; Dudko, Lev V.; /Durham U.; Ferland, J.; /Montreal U.; Gershtein, Yuri S.; /Florida State U.; Gigg, M.; /Durham U.; Gonzalez de la Hoz, S.; /Valencia U., IFIC; Herquet, M.; /Louvain U.; Hirn, J.; /Yale U. /Brown U. /Boston U. /Annecy, LAPTH /INFN, Turin /Valencia U., IFIC /Yale U. /Arizona U. /Louis Pasteur U., Strasbourg I /Orsay, LAL /KEK, Tsukuba /Moscow State U. /Lisbon, LIFEP /CERN /Durham U. /Valencia U., IFIC /Sao Paulo, IFT /Fermilab /Zurich, ETH /Boston U. /DESY /CERN /Saclay, SPhT /Durham U. /Cambridge U. /Michigan State U. /Louis Pasteur U., Strasbourg I /Orsay, LAL /Annecy, LAPTH /Fermilab /CERN /Arizona U. /Northwestern U. /Argonne /Kyoto U. /Valencia U., IFIC /UC, Berkeley /LBL, Berkeley

2011-12-05T23:59:59.000Z

385

Advanced Simulation Capability for  

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

Simulation Capability for Simulation Capability for Environmental Management (ASCEM) ASCEM is being developed to provide a tool and approach to facilitate robust and standardized development of perfor- mance and risk assessments for cleanup and closure activi- ties throughout the EM complex. The ASCEM team is composed of scientists from eight National Laboratories. This team is leveraging Department of Energy (DOE) investments in basic science and applied research including high performance computing codes developed through the Advanced Scientific Computing Research and Advanced Simulation & Computing pro- grams as well as collaborating with the Offices of Science, Fossil Energy, and Nuclear Energy. Challenge Current groundwater and soil remediation challenges that will continue to be addressed in the next decade include

386

Flight code validation simulator  

Science Conference Proceedings (OSTI)

An End-To-End Simulation capability for software development and validation of missile flight software on the actual embedded computer has been developed utilizing a 486 PC, i860 DSP coprocessor, embedded flight computer and custom dual port memory interface hardware. This system allows real-time interrupt driven embedded flight software development and checkout. The flight software runs in a Sandia Digital Airborne Computer (SANDAC) and reads and writes actual hardware sensor locations in which IMU (Inertial Measurements Unit) data resides. The simulator provides six degree of freedom real-time dynamic simulation, accurate real-time discrete sensor data and acts on commands and discretes from the flight computer. This system was utilized in the development and validation of the successful premier flight of the Digital Miniature Attitude Reference System (DMARS) in January 1995 at the White Sands Missile Range on a two stage attitude controlled sounding rocket.

Sims, B.A.

1995-08-01T23:59:59.000Z

387

Simulating neural systems with Xyce.  

SciTech Connect

Sandia's parallel circuit simulator, Xyce, can address large scale neuron simulations in a new way extending the range within which one can perform high-fidelity, multi-compartment neuron simulations. This report documents the implementation of neuron devices in Xyce, their use in simulation and analysis of neuron systems.

Schiek, Richard Louis; Thornquist, Heidi K.; Mei, Ting; Warrender, Christina E.; Aimone, James Bradley; Teeter, Corinne; Duda, Alex M. [University of Illinois, Urbana-Champaign] University of Illinois, Urbana-Champaign

2012-12-01T23:59:59.000Z

388

Advanced Simulation and Computing  

National Nuclear Security Administration (NNSA)

NA-ASC-117R-09-Vol.1-Rev.0 NA-ASC-117R-09-Vol.1-Rev.0 Advanced Simulation and Computing PROGRAM PLAN FY09 October 2008 ASC Focal Point Robert Meisner, Director DOE/NNSA NA-121.2 202-586-0908 Program Plan Focal Point for NA-121.2 Njema Frazier DOE/NNSA NA-121.2 202-586-5789 A Publication of the Office of Advanced Simulation & Computing, NNSA Defense Programs i Contents Executive Summary ----------------------------------------------------------------------------------------------- 1 I. Introduction -------------------------------------------------------------------------------------------------------- 2 Realizing the Vision ------------------------------------------------------------------------------------------------- 2 The Future of the Nuclear Weapons Complex ---------------------------------------------------------------- 2

389

Toroidal simulation magnet tests  

SciTech Connect

A number of different schemes for testing superconducting coils in a simulated tokamak environment are analyzed for their merits relative to a set of test criteria. Two of the concepts are examined in more detail: the so-called cluster test scheme, which employs two large background field coils, one on either side of the test coil, and the compact torus, a low-aspect ratio toroidal array of a small number of coils in which all of the coils are essentially test coils. Simulation of the pulsed fields of the tokamak is discussed briefly. (auth)

Walstrom, P.L.; Domm, T.C.

1975-01-01T23:59:59.000Z

390

Simulation des coulements souterrains dans un aquifre alluvial : contribution l'tude de la nappe de l'Isre dans la Combe de Savoie (France) - Alpes franaises.  

E-Print Network (OSTI)

??Dans la Combe de Savoie , entre Albertville et Montmlian, les alluvions modernes de l'Isre reclent une nappe en troite liaison avec les cours d (more)

Monier, Thierry

391

PARTIALLY AVERAGED NAVIER-STOKES METHOD FOR TURBULENCE CLOSURES: CHARACTERIZATION OF FLUCTUATIONS AND EXTENSION TO WALL BOUNDED FLOWS  

E-Print Network (OSTI)

The work presented in this dissertation concerns continued development, validation and verification of the partially averaged Navier-Stokes (PANS) method - a variable resolution closure model for turbulence. Linear eddy viscosity models (LEVM), which are popular because of their simplicity and affordability in terms of computational cost have fundamental deficiencies and cannot be trusted to accurately represent turbulence in realistic complex flows. The more high fidelity approaches such as large eddy simulations (LES) and direct numerical simulations (DNS) are out of realm of engineering applicability because of their high requirements in computing power. PANS, a variable resolution approach considered in this study, lies between LEVM and LES in terms of computational cost and is designed to prudently utilize the available computing power to improve accuracy. This dissertation presents the various studies performed to characterize the PANS fluctuations and extend the model for use in various wall bounded flows. The road map towards our goal includes: (i) Comparing a-priori and a-posteriori eddy viscosity values to establish whether PANS is capable of producing the pre-specified level of reduction. (ii) Investigating the scaling of PANS fluctuations for different levels of prescribed resolution and establishing if the fluctuations abide by known turbulence scaling laws. (iii) Extending PANS to k-w formulation which is better suited for wall-bounded shear flows, and (iv) Modifying the present LEVM to yield reasonable behavior in the rapid distortion limit where the turbulence is elastic in nature which ultimately affects PANS performance. Results reported in this dissertation illustrate that the PANS closure yields reliable and predictable reduction in the modeled viscosity. The accuracy of the simulations improve as the effective damping is reduced by lowering the specified viscosity providing credibility to the PANS method as a bridging model that performs as intended.

Lakshmipathy, Sunil

2009-05-01T23:59:59.000Z

392

Hermeneutique des Tantra : les Six extremes (ou possibilites alternatives) (satkoti ; mtha' drug). A propos d'un exemple de pregnance des modeles exegetiques des sutra  

E-Print Network (OSTI)

deux ornements ont pour fonction assigne, selon Tsong kha pa (1357-1419), de commenter la pense [ou lintention (dgongs pa ; abhiprya)] du tantra-racine12. Mais, alors que lesQuatre modes dexplication sont exclusivement utiliss pour les tantra... , Collge de France, Institut de Civilisation Indienne, 1978, p. 15). Bu ston rin chen grub (1290-1364) et Tsong kha pa (1357-1419) utilisent cette grille pour commenter le troisime et le quatrime ornement (v. A. Wayman, The Buddhist Tantras, Light...

Arenes, Pierre

2002-01-01T23:59:59.000Z

393

Simulation of geothermal subsidence  

DOE Green Energy (OSTI)

The results of an assessment of existing mathematical models for subsidence simulation and prediction are summarized. The following subjects are discussed: the prediction process, physical processes of geothermal subsidence, computational models for reservoir flow, computational models for deformation, proficiency assessment, and real and idealized case studies. (MHR)

Miller, I.; Dershowitz, W.; Jones, K.; Myer, L.; Roman, K.; Schauer, M.

1980-03-01T23:59:59.000Z

394

Ion trap simulation tools.  

Science Conference Proceedings (OSTI)

Ion traps present a potential architecture for future quantum computers. These computers are of interest due to their increased power over classical computers stemming from the superposition of states and the resulting capability to simultaneously perform many computations. This paper describes a software application used to prepare and visualize simulations of trapping and maneuvering ions in ion traps.

Hamlet, Benjamin Roger

2009-02-01T23:59:59.000Z

395

The Thermally Driven Cross-Basin Circulation in Idealized Basins under Varying Wind Conditions  

Science Conference Proceedings (OSTI)

The Weather Research and Forecasting model is used to perform large-eddy simulations of thermally driven cross-basin winds in idealized, closed basins. A spatially and temporally varying heat flux is prescribed at the surface as a function of ...

Manuela Lehner; C. David Whiteman

2012-06-01T23:59:59.000Z

396

Acta Geophysica vol. 56, no. 1, pp. 88-99  

E-Print Network (OSTI)

surface roughness length for heat potential temperature difference between first model grid of Geophysics, Polish Academy of Sciences An inconvenient "truth" about using sensible heat flux as a surface column and large-eddy simulation studies of the atmospheric bound- ary layer, surface sensible heat flux

Basu, Sukanta

397

Wind-Driven Mixing below the Oceanic Mixed Layer  

Science Conference Proceedings (OSTI)

This study describes the turbulent processes in the upper ocean boundary layer forced by a constant surface stress in the absence of the Coriolis force using large-eddy simulation. The boundary layer that develops has a two-layer structure, a well-...

Alan L. M. Grant; Stephen E. Belcher

2011-08-01T23:59:59.000Z

398

CALTECH ASCI TECHNICAL REPORT 165 Reconstruction of subgrid models for nonpremixed combustion  

E-Print Network (OSTI)

CALTECH ASCI TECHNICAL REPORT 165 Reconstruction of subgrid models for nonpremixed combustion J. P. Medallo, S. Sarkar and C. Pantano #12;Reconstruction subgrid models for nonpremixed combustion J. P 2003; published 16 September 2003 Large-eddy simulation of combustion problems involves highly

399

Budgets of Lineal and Nonlineal Turbulent Kinetic Energy under Strong Shear Conditions  

Science Conference Proceedings (OSTI)

Quasi-lineal roll coherent structures appear in a large eddy simulation of strong wind shear and moderate surface buoyancy flux. Unlike idealized two-dimensional roll vortices, these rolls are finite in length and vary in axial angle. Over a ...

John W. Glendening

2000-07-01T23:59:59.000Z

400

Dependence of a Plume Heat Budget upon Lateral Advection  

Science Conference Proceedings (OSTI)

The structure and heat budget of a plume created by a linear heat source is investigated, demonstrating their dependence upon the larger-scale cross-source flow. A large-eddy model simulates individual thermal eddies produced by a source 200 m ...

John W. Glendening

1994-12-01T23:59:59.000Z

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

To link to this article: DOI:10.1016/j.pecs.2012.04.004 URL : http://dx.doi.org/10.1016/j.pecs.2012.04.004  

E-Print Network (OSTI)

flames in gas turbine combustion chambers. (2012) Progress in Energy and Combustion Science, vol. 38 (n.pecs.2012.04.004 #12;Large Eddy Simulations of gaseous flames in gas turbine combustion chambers L for aeronautical gas turbine burners are reviewed: (1) laboratory-scale combustors, without compressor or turbine

Paris-Sud XI, Université de

402

Original article: A numerical estimate of the plankton-induced sea surface tension effects in a Langmuir circulation  

Science Conference Proceedings (OSTI)

Marine phytoplankton is known to produce surface-active materials as part of its metabolism. The sea surface tension gradient due to the presence of plankton produced surfactants leads to a surface shear stress, commonly known as Marangoni stress, that ... Keywords: Film pressure, Finite volumes, Langmuir circulation, Large Eddy Simulation, Plankton

Vincenzo Botte; Daniela Mansutti

2012-08-01T23:59:59.000Z

403

A Combined Local and Nonlocal Closure Model for the Atmospheric Boundary Layer. Part II: Application and Evaluation in a Mesoscale Meteorological Model  

Science Conference Proceedings (OSTI)

A new combined local and nonlocal closure atmospheric boundary layer model called the Asymmetric Convective Model, version 2, (ACM2) was described and tested in one-dimensional form and was compared with large-eddy simulations and field data in ...

Jonathan E. Pleim

2007-09-01T23:59:59.000Z

404

The Influence of Wind Speed on Shallow Marine Cumulus Convection  

Science Conference Proceedings (OSTI)

The role of wind speed on shallow marine cumulus convection is explored using large-eddy simulations and concepts from bulk theory. Focusing on cases characteristic of the trades, the equilibrium trade wind layer is found to be deeper at stronger ...

Louise Nuijens; Bjorn Stevens

2012-01-01T23:59:59.000Z

405

The Effects of Aircraft Wake Dynamics on Contrail Development  

Science Conference Proceedings (OSTI)

Results of large-eddy simulations of the development of young persistent ice contrails are presented, concentrating on the interactions between the aircraft wake dynamics and the ice cloud evolution over ages from a few seconds to 30 min. The 3D ...

D. C. Lewellen; W. S. Lewellen

2001-02-01T23:59:59.000Z

406

The Wavy Ekman Layer: Langmuir Circulations, Breaking Waves, and Reynolds Stress  

Science Conference Proceedings (OSTI)

Large-eddy simulations are made for the canonical Ekman layer problem of a steady wind above a uniformly rotating, constant-density ocean. The focus is on the influence of surface gravity waves: namely, the wave-averaged Stokes-Coriolis and Stokes-...

James C. McWilliams; Edward Huckle; Jun-Hong Liang; Peter P. Sullivan

2012-11-01T23:59:59.000Z

407

Nature versus Nurture in Shallow Convection  

Science Conference Proceedings (OSTI)

Tracers are used in a large-eddy simulation of shallow convection to show that stochastic entrainment (and not cloud-base properties) determines the fate of convecting parcels. The tracers are used to diagnose the correlations between a parcels ...

David M. Romps; Zhiming Kuang

2010-05-01T23:59:59.000Z

408

Simulation Data as Data Streams  

SciTech Connect

Computational or scientific simulations are increasingly being applied to solve a variety of scientific problems. Domains such as astrophysics, engineering, chemistry, biology, and environmental studies are benefiting from this important capability. Simulations, however, produce enormous amounts of data that need to be analyzed and understood. In this overview paper, we describe scientific simulation data, its characteristics, and the way scientists generate and use the data. We then compare and contrast simulation data to data streams. Finally, we describe our approach to analyzing simulation data, present the AQSim (Ad-hoc Queries for Simulation data) system, and discuss some of the challenges that result from handling this kind of data.

Abdulla, G; Arrighi, W; Critchlow, T

2003-11-18T23:59:59.000Z

409

Simulation of biochemical networks using COPASI: a complex pathway simulator  

Science Conference Proceedings (OSTI)

Simulation and modeling is becoming one of the standard approaches to understand complex biochemical processes. Therefore, there is a big need for software tools that allow access to diverse simulation and modeling methods as well as support for the ...

Sven Sahle; Ralph Gauges; Jrgen Pahle; Natalia Simus; Ursula Kummer; Stefan Hoops; Christine Lee; Mudita Singhal; Liang Xu; Pedro Mendes

2006-12-01T23:59:59.000Z

410

Simulation-based optimization: practical introduction to simulation optimization  

Science Conference Proceedings (OSTI)

The merging of optimization and simulation technologies has seen a rapid growth in recent years. A Google search on "Simulation Optimization" returns more than six thousand pages where this phrase appears. The content of these pages ranges from articles, ...

Jay April; Fred Glover; James P. Kelly; Manuel Laguna

2003-12-01T23:59:59.000Z

411

Simulation standards: a framework for standard modular simulation  

Science Conference Proceedings (OSTI)

The primary reason for building manufacturing simulations is to provide support tools that aid the manufacturing decision-making process. Simulations are typically a part of a case study commissioned by manufacturing management to address a particular ...

Charles McLean; Swee Leong

2002-12-01T23:59:59.000Z

412

Risk Analysis and Simulation  

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

Analysis and Simulation Analysis and Simulation for Geologic Storage of CO 2 BEST PRACTICES for: 2013 Revised Edition Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The

413

The Simulation Intranet Architecture  

Science Conference Proceedings (OSTI)

The Simdarion Infranet (S1) is a term which is being used to dcscribc one element of a multidisciplinary distributed and distance computing initiative known as DisCom2 at Sandia National Laboratory (http ct al. 1998). The Simulation Intranet is an architecture for satisfying Sandia's long term goal of providing an end- to-end set of scrviccs for high fidelity full physics simu- lations in a high performance, distributed, and distance computing environment. The Intranet Architecture group was formed to apply current distributed object technologies to this problcm. For the hardware architec- tures and software models involved with the current simulation process, a CORBA-based architecture is best suited to meet Sandia's needs. This paper presents the initial desi-a and implementation of this Intranct based on a three-tier Network Computing Architecture(NCA). The major parts of the architecture include: the Web Cli- ent, the Business Objects, and Data Persistence.

Holmes, V.P.; Linebarger, J.M.; Miller, D.J.; Vandewart, R.L.

1998-12-02T23:59:59.000Z

414

Radiation in Particle Simulations  

SciTech Connect

Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of fusion ignition plasmas including the important effects of radiation emission and absorption.

More, R; Graziani, F; Glosli, J; Surh, M

2010-11-19T23:59:59.000Z

415

Fast Simulation and Modeling  

Science Conference Proceedings (OSTI)

The "Fast Simulation and Modeling" (FSM) project of the IntelliGrid Consortium is developing a high-performance "look-ahead" capability for a self-healing grid8212one capable of automatically anticipating and responding to power system disturbances while continually optimizing its own performance. This project's roadmap assesses individual software solutions and equipment components that vendors will provide during the next 5 to 15 years and that electric power companies will adopt to realize FSM's self-...

2007-12-19T23:59:59.000Z

416

Performance simulation and prediction  

DOE Green Energy (OSTI)

Computational procedures useful during the passive solar design process are discussed. Analysis tools are described suitable for each of the three phases of design: rules of thumb for the concept development phase, quick-and-dirty techniques for the design development phase, and the monthly solar load ratio method for the final design phase. Issues are discussed regarding the role of simulation analysis during the design process.

Balcomb, J.D.

1979-01-01T23:59:59.000Z

417

COLLABORATIVE: FUSION SIMULATION PROGRAM  

SciTech Connect

New York University, Courant Institute of Mathematical Sciences, participated in the ???¢????????Fusion Simulation Program (FSP) Planning Activities???¢??????? [http://www.pppl.gov/fsp], with C.S. Chang as the institutional PI. FSP???¢????????s mission was to enable scientific discovery of important new plasma phenomena with associated understanding that emerges only upon integration. This requires developing a predictive integrated simulation capability for magnetically-confined fusion plasmas that are properly validated against experiments in regimes relevant for producing practical fusion energy. Specific institutional goal of the New York University was to participate in the planning of the edge integrated simulation, with emphasis on the usage of large scale HPCs, in connection with the SciDAC CPES project which the PI was leading. New York University successfully completed its mission by participating in the various planning activities, including the edge physics integration, the edge science drivers, and the mathematical verification. The activity resulted in the combined report that can be found in http://www.pppl.gov/fsp/Overview.html. Participation and presentations as part of this project are listed in a separation file.

Chang, Choong Seock

2012-06-05T23:59:59.000Z

418

H. KAYSER. -Ueber den Einfluss der Temperatur auf Stimmgabeln (Influence de la temprature sur les diapasons); Ann. der Physik und Chemie, nouvelle srie,  

E-Print Network (OSTI)

les diapasons); Ann. der Physik und Chemie, nouvelle série, t. VIII, p. 444; I879. Le nombre des'oxygène liquéfié, p. 27 1 . Annalen der Physik und Chemie. Nouvelle série. - Tome IX. - N° 2. - Année 1880. W

Paris-Sud XI, Université de

419

Multi-Hundred Watt Radioisotope Thermoelectric Generator Program, LES 8/9 Program, MJS Program, Bi-monthly progress report, 1 November--31 December 1975  

DOE Green Energy (OSTI)

Significant events, activities and achievements on the MHW LES 8/9 and MJS Programs for the reporting period are reported. Topics discussed include safety systems, isotope heat source, converter, product assurance, hardware fabrication, acceptance testing, and ground support equipment. (TFD)

Not Available

1975-01-01T23:59:59.000Z

420

Multi-Hundred Watt Radioisotope Thermoelectric Generator Program, LES 8/9 Program, MJS Program. Bi-monthly progress report, 1 May--30 June 1975  

DOE Green Energy (OSTI)

Significant events, activities and achievements on the MHW LES 8/9 and MJS Programs for the reporting period are reported. Topics discussed include programmatic, safety, systems, isotope heat source, converter, product assurance, hardware fabrication, acceptance testing, and ground support equipment. (TFD)

Not Available

1975-01-01T23:59:59.000Z

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421

Google au quotidien : le googling ou les habitudes de recherche de l'internaute ordinaire Page 1 sur 12 GOOGLE AU QUOTIDIEN : LE GOOGLING EN PERSPECTIVE  

E-Print Network (OSTI)

Google au quotidien : le googling ou les habitudes de recherche de l'internaute ordinaire Page 1 sur 12 GOOGLE AU QUOTIDIEN : LE GOOGLING EN PERSPECTIVE Philippe Dumas, Professeur en Sciences de l recherche d'information à partir d'une étude sociolinguistique des discours sur Google. Mots clés : Usages

Paris-Sud XI, Université de

422

Lecture Session (LeS): E.4 REMEDIATION Thermal techniques -1 STEAM-AIR-INJECTION FOR IN-SITU GROUNDWATER AND SOIL REMEDIATION: PILOT  

E-Print Network (OSTI)

Lecture Session (LeS): E.4 REMEDIATION Thermal techniques -1 STEAM-AIR-INJECTION FOR IN@iws.uni-stuttgart.de Keywords: Partial Source removal, thermally enhanced soil vapor extraction, steam-air-injection, pilot methods (steam-air injection and thermal wells), developed and verified in several field applications

Cirpka, Olaf Arie

423

Multi-Hundred Watt Radioisotope Thermoelectric Generator Program, LES 8/9 Program, MJS Program. Bi-monthly progress report, 1 July--31 August 1975  

DOE Green Energy (OSTI)

Significant events, activities and achievements on the MHW LES 8/9 and MJS Programs for the reporting period are reported. Topics discussed include safety systems, isotope heat source, converter, product assurance, hardware fabrication, acceptance testing, and ground support equipment. (TFD)

Not Available

1975-01-01T23:59:59.000Z

424

Virtual urban traffic network simulator  

E-Print Network (OSTI)

In this project, I designed and implemented a virtual urban traffic network simulator. The simulator serves as a testbed for human-subject experiments to determine driver behavior in road networks and also as a platform ...

Uh, Jason (Jason J.)

2011-01-01T23:59:59.000Z

425

Translation Effects on Simulated Tornadoes  

Science Conference Proceedings (OSTI)

A simulation of tornadoes translating over the ground was carried out in a modified Ward simulator. The purpose was to investigate the effects of translation on tornado dynamics. The results are as follows:

Chris J. Diamond; Eugene M. Wilkins

1984-09-01T23:59:59.000Z

426

Computer simulations of cardiac electrophysiology  

Science Conference Proceedings (OSTI)

CardioWave is a modular system for simulating wavefront conduction in the heart. These simulations may be used to investigate the factors that generate and sustain life-threatening arrhythmias such as ventricular fibrillation. The user selects a set ...

John B. Pormann; Craig S. Henriquez; John A. Board, Jr.; Donald J. Rose; David M. Harrild; Alexandra P. Henriquez

2000-11-01T23:59:59.000Z

427

A Simulation of Alberta Cumulus  

Science Conference Proceedings (OSTI)

A two-dimensional cloud model was used to simulate an Alberta, Canada, seeding experiment that was conducted on 24 July 1979, by the Alberta Research Council. The simulation reproduced some of the characteristics of the silver iodide seeded cloud ...

Fred J. Kopp

1988-05-01T23:59:59.000Z

428

Design of mechanical arterial simulator  

E-Print Network (OSTI)

A force controlled ultrasound probe is being explored as a new method of measuring blood pressure. An arterial simulator was designed and built for experiments. For this simulator, the vessels and bulk material were designed ...

Chai, Lauren (Lauren Amy)

2012-01-01T23:59:59.000Z

429

Simulations of nanoscale spatial disorder  

E-Print Network (OSTI)

In this thesis, we detail the design, implementation, and testing of two simulations of nanometer scale disorder phenomena important for electronic device fabrication. We created a kinetic simulator for the surface assembly ...

Howe, Ethan (Ethan Gabriel Grief)

2006-01-01T23:59:59.000Z

430

Simulation of Sextet Diquark Production  

E-Print Network (OSTI)

We present a method for simulating the production and decay of particles in the sextet representation of $SU(3)_C$ including the simulation of QCD radiation. First results from the Monte Carlo simulation of sextet diquark production at the LHC including both resonant and pair production are presented. We include limits on resonant diquark production from recent ATLAS results and perform the first simulation studies of the less model dependent pair production mechanism.

Peter Richardson; David Winn

2011-08-31T23:59:59.000Z

431

Residual Stresses and Numerical Simulation  

Science Conference Proceedings (OSTI)

Oct 28, 2013 ... Advances in Hydroelectric Turbine Manufacturing and Repair: Residual Stresses and Numerical Simulation Sponsored by: Metallurgical...

432

Circuit simulation: some humbling thoughts  

Science Conference Proceedings (OSTI)

A short, very personal note on circuit simulation is presented. It does neither include theoretical background on circuit simulation, nor offers an overview of available software, but just gives some general remarks for a discussion on circuit simulator needs in context to the design and development of accelerator beam instrumentation circuits and systems.

Wendt, Manfred; /Fermilab

2006-01-01T23:59:59.000Z

433

Bio-threat microparticle simulants  

SciTech Connect

A bio-threat simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the bio-threat simulant.

Farquar, George Roy; Leif, Roald N

2012-10-23T23:59:59.000Z

434

Simulation in education and training  

Science Conference Proceedings (OSTI)

Historically, the use of simulation has been an important aspect of training in some fields (such as aviation). As the cost of computing power decreases simulation is now finding its way into training for other fields. As simulation moves into these ...

J. Peter Kincaid; Ken K. Westerlund

2009-12-01T23:59:59.000Z

435

Utility Analysis of Parallel Simulation  

Science Conference Proceedings (OSTI)

Parallel computers are used to execute discrete-event simulations in contexts where a serial computer is unable to provide answers fast enough, and/or is unable to hold the simulation state in memory. Traditional research in parallel simulation has focused ...

David M. Nicol

2003-06-01T23:59:59.000Z

436

Plasma Simulation Program  

SciTech Connect

Many others in the fusion energy and advanced scientific computing communities participated in the development of this plan. The core planning team is grateful for their important contributions. This summary is meant as a quick overview the Fusion Simulation Program's (FSP's) purpose and intentions. There are several additional documents referenced within this one and all are supplemental or flow down from this Program Plan. The overall science goal of the DOE Office of Fusion Energy Sciences (FES) Fusion Simulation Program (FSP) is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in International Thermonuclear Experimental Reactor (ITER) research and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical Integrated Science Application (ISA) areas: ISA1, the plasma edge; and ISA2, whole device modeling (WDM) including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical impediment to successful operation of machines like ITER. If disruptions prove unable to be avoided, their associated dynamics and effects will be addressed in the next phase of the FSP.

Greenwald, Martin

2011-10-04T23:59:59.000Z

437

SEALING SIMULATED LEAKS  

Science Conference Proceedings (OSTI)

This report details the testing equipment, procedures and results performed under Task 7.2 Sealing Simulated Leaks. In terms of our ability to seal leaks identified in the technical topical report, Analysis of Current Field Data, we were 100% successful. In regards to maintaining seal integrity after pigging operations we achieved varying degrees of success. Internal Corrosion defects proved to be the most resistant to the effects of pigging while External Corrosion proved to be the least resistant. Overall, with limitations, pressure activated sealant technology would be a viable option under the right circumstances.

Michael A. Romano

2004-09-01T23:59:59.000Z

438

Maintenance simulation: Software issues  

SciTech Connect

The maintenance of a distributed software system in a production environment involves: (1) maintaining software integrity, (2) maintaining and database integrity, (3) adding new features, and (4) adding new systems. These issues will be discussed in general: what they are and how they are handled. This paper will present our experience with a distributed resource management system that accounts for resources consumed, in real-time, on a network of heterogenous computers. The simulated environments to maintain this system will be presented relate to the four maintenance areas.

Luk, C.H.; Jette, M.A.

1995-07-01T23:59:59.000Z

439

Fusion Simulation Program  

Science Conference Proceedings (OSTI)

Under this project, General Atomics (GA) was tasked to develop the experimental validation plans for two high priority ISAs, Boundary and Pedestal and Whole Device Modeling in collaboration with the theory, simulation and experimental communities. The following sections have been incorporated into the final FSP Program Plan (www.pppl.gov/fsp), which was delivered to the US Department of Energy (DOE). Additional deliverables by GA include guidance for validation, development of metrics to evaluate success and procedures for collaboration with experiments. These are also part of the final report.

Project Staff (V.S. Chan)

2012-02-29T23:59:59.000Z

440

NETL: Discrete Fracture Reservoir Simulation Software  

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

Discrete Fracture Reservoir Simulation FRACGENNFFLOW Shale Gas Flow Simulation Shale Gas Flow Simulation FRACGENNFFLOW, a fractured reservoir modeling software developed by the...

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

Manet simulation studies: The incredibles  

E-Print Network (OSTI)

Simulation is the research tool of choice for a majority of the mobile ad hoc network (MANET) community. However, while the use of simulation has increased, the credibility of the simulation results has decreased. To determine the state of MANET simulation studies, we surveyed the 2000-2005 proceedings of the ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc). From our survey, we found significant shortfalls. We present the results of our survey in this paper. We then summarize common simulation study pitfalls found in our survey. Finally, we discuss the tools available that aid the development of rigorous simulation studies. We offer these results to the community with the hope of improving the credibility of MANET simulation-based studies. I.

Stuart Kurkowski; Tracy Camp; Michael Colagrosso

2005-01-01T23:59:59.000Z

442

Fading channel simulator  

DOE Patents (OSTI)

This invention relates to high frequency (HF) radio signal propagation through fading channels and, more particularly, to simulation of fading channels in order to characterize HF radio system performance in transmitting and receiving signals through such fading channels. Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

Argo, P.E.; Fitzgerald, T.J.

1991-12-31T23:59:59.000Z

443

Numerical modeling of species transport in turbulent flow and experimental study on aerosol sampling  

E-Print Network (OSTI)

Numerical simulations were performed to study the turbulent mixing of a scalar species in straight tube, single and double elbow flow configurations. Different Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) models were used to model the turbulence in the flow. Conventional and dynamic Smagorinsky sub-grid scale models were used for the LES simulations. Wall functions were used to resolve the near wall boundary layer. These simulations were run with both two-dimensional and three-dimensional geometries. The velocity and tracer gas concentration Coefficient of Variations were compared with experimental results. The results from the LES simulations compared better with experimental results than the results from the RANS simulations. The level of mixing downstream of a S-shaped double elbow was higher than either the single elbow or the U-shaped double elbow due to the presence of counter rotating vortices. Penetration of neutralized and non-neutralized aerosol particles through three different types of tubing was studied. The tubing used included standard PVC pipes, aluminum conduit and flexible vacuum hose. Penetration through the aluminum conduit was unaffected by the presence or absence of charge neutralization, whereas particle penetrations through the PVC pipe and the flexible hosing were affected by the amount of particle charge. The electric field in a space enclosed by a solid conductor is zero. Therefore charged particles within the conducting aluminum conduit do not experience any force due to ambient electric fields, whereas the charged particles within the non-conducting PVC pipe and flexible hose experience forces due to the ambient electric fields. This increases the deposition of charged particles compared to neutralized particles within the 1.5� PVC tube and 1.5� flexible hose. Deposition 2001a (McFarland et al. 2001) software was used to predict the penetration through transport lines. The prediction from the software compared well with experiments for all cases except when charged particles were transported through non-conducting materials. A Stairmand cyclone was designed for filtering out large particles at the entrance of the transport section.

Vijayaraghavan, Vishnu Karthik

2006-12-01T23:59:59.000Z

444

Disens: scalable distributed sensor network simulation  

Science Conference Proceedings (OSTI)

Simulation is widely used for developing, evaluating and analyzing sensor network applications, especially when deploying a large scale sensor network remains expensive and labor intensive. However, due to its computation intensive nature, existent simulation ... Keywords: distributed simulation, sensor network, simulation

Ye Wen; Rich Wolski; Gregory Moore

2007-03-01T23:59:59.000Z

445

THERM NFRC Simulation Manual  

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

/ WINDOW 6.3 / WINDOW 6.3 NFRC Simulation Manual Lawrence Berkeley National Laboratory July 2013 DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement,

446

Cellular array processing simulation  

Science Conference Proceedings (OSTI)

The cellular array processing simulation (CAPS) system is a high-level image language that runs on a multiprocessor configuration. CAPS is interpretively decoded on a conventional minicomputer with all image operation instructions executed on an array processor. CAPS was designed to be both modular and table driven so that it can be easily maintained and modified. CAPS uses the image convolution operator as one of its primitives and performs this cellular operation by decomposing it into parallel image steps. Among its features is the ability to observe the imagery in real time as a user's algorithm is executed. CAPS also contains a language processor that permits users to develop re-entrant image processing subroutines or algorithms. 4 references.

Lee, H.C.; Preston, E.W.

1981-01-01T23:59:59.000Z

447

Lattice Boltzmann Simulation Optimization  

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

Boltzmann Boltzmann Simulation Optimization on Leading Multicore Platforms Selected as Best Paper in Application Track, IPDPS 2008, April 14-28, Miami, Florida, USA Samuel Williams † , Jonathan Carter , Leonid Oliker John Shalf , Katherine Yelick † CRD/NERSC, Lawrence Berkeley National Laboratory Berkeley, CA 94720 † CS Division, University of California at Berkeley, Berkeley, CA 94720 {SWWilliams, JTCarter, LOliker, JShalf, KAYelick}@lbl.gov Abstract We present an auto-tuning approach to optimize ap- plication performance on emerging multicore architec- tures. The methodology extends the idea of search- based performance optimizations, popular in linear al- gebra and FFT libraries, to application-specific com- putational kernels. Our work applies this strategy to a lattice Boltzmann application (LBMHD) that histor- ically has made poor use of scalar microprocessors

448

Advanced Simulation Capability for Environmental Management  

Multi-Process High Performance Computing Simulator Modular simulation capability for barrier and waste form degradation, multiphase flow and reactive ...

449

Quantum to Atomistic Simulations - Programmaster.org  

Science Conference Proceedings (OSTI)

Computational Modeling and Simulation of Advanced Materials for Energy Applications: Quantum to Atomistic Simulations Sponsored by: TMS/ASM:...

450

Non-detonable explosive simulators  

DOE Patents (OSTI)

A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules. 5 figs.

Simpson, R.L.; Pruneda, C.O.

1994-11-01T23:59:59.000Z

451

Non-detonable explosive simulators  

DOE Patents (OSTI)

A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules.

Simpson, Randall L. (Livermore, CA); Pruneda, Cesar O. (Livermore, CA)

1994-01-01T23:59:59.000Z

452

NIST Standard Reference Simulation Website  

Science Conference Proceedings (OSTI)

... simulations, that can be treated similar to "standard reference data ... techniques and compiled by NIST under the Standards Reference Data Program. ...

2013-08-27T23:59:59.000Z

453

Real time wind turbine simulator.  

E-Print Network (OSTI)

??A novel dynamic real-time wind turbine simulator (WTS) is developed in this thesis, which is capable of reproducing dynamic behavior of real wind turbine. The (more)

Gong, Bing

2007-01-01T23:59:59.000Z

454

Simulation I - Programmaster.org  

Science Conference Proceedings (OSTI)

Feb 15, 2010 ... Molecular dynamics Simulation of Nucleation Process: Ramanarayan Hariharaputran1; David Wu1; 1Institute of High Performance Computing,...

455

Computer interactive resistance simulator (CIRS)  

DOE Patents (OSTI)

A system for simulating the insertion of electric resistance values of either positive or negative quantity into an electric circuit and for cancelling drift errors therefrom.

Mayn, Bobby G. (Pleasanton, CA)

1976-01-01T23:59:59.000Z

456

Computational simulation of aerosol behaviour.  

E-Print Network (OSTI)

??In this thesis, computational methods have been developed for the simulation of aerosol dynamics and transport. Two different coupled aerosol-computational fluid dynamics (CFD) models are (more)

Pyyknen, Jouni

2002-01-01T23:59:59.000Z

457

Logic Simulation Using Graphics Processors.  

E-Print Network (OSTI)

??Logic Simulation is widely used to verify the logical correctness of hardware designs. In this work, we present the implementation of a generic graphics processor (more)

Perinkulam, Atchuthan S

2007-01-01T23:59:59.000Z

458

LAMMPS Molecular Dynamics Simulator - TMS  

Science Conference Proceedings (OSTI)

Nov 8, 2007 ... LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel Simulator. LAMMPS has potentials for soft materials (biomolecules,...

459

Occupancy Simulation Schedule Appendix C -Occupancy Simulation Schedule  

E-Print Network (OSTI)

into the electrical panel for run times commensurate with identified use profiles. The profiles enabled sought Figure C.1 and Figure C.2 present the load simulation and occupancy schedules for the lab homes highly insulating windows demonstration. The bases for occupancy simulation were data and analysis developed

460

9/7/2013 Toutes les informations donnes sur cette page sont indicatives et n'ont pas de valeur contractuelle Page 1 / 13  

E-Print Network (OSTI)

, littérature et cinéma, linguistique, histoire de la langue, français langue étrangère, histoire de l siècle (3 ECTS) 6 6 UEF2 LINGUISTIQUE TD Grammaire de la phrase simple 5 5 UEF3 M?THODOLOGIE TD ECTS) 6 6 UEF2 LINGUISTIQUE CM Introduction à la linguistique (2 ECTS) 5 5 #12;9/7/2013 Toutes les

Pravda-Starov, Karel

Note: This page contains sample records for the topic "large-eddy simulation les" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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461

9/7/2013 Toutes les informations donnes sur cette page sont indicatives et n'ont pas de valeur contractuelle MASTER LITTERATURES DU MONDE FRANCOPHONE  

E-Print Network (OSTI)

Linguistique et analyse du discours Linguistique textuelle 6 6 #12;9/7/2013 Toutes les informations données sur francophone : Littérature et échanges culturels L'autre francophonie Roman et histoire Linguistique et analyse'ont pas de valeur contractuelle Page 4 / 6 Linguistique textuelle Langue et société Un séminaire à choisir

Pravda-Starov, Karel

462

Simulating nanoscale semiconductor devices.  

SciTech Connect

The next generation of electronic devices will be developed at the nanoscale and molecular level, where quantum mechanical effects are observed. These effects must be accounted for in the design process for such small devices. One prototypical nanoscale semiconductor device under investigation is a resonant tunneling diode (RTD). Scientists are hopeful the quantum tunneling effects present in an RTD can be exploited to induce and sustain THz frequency current oscillations. To simulate the electron transport within the RTD, the Wigner-Poisson equations are used. These equations describe the time evolution of the electrons distribution within the device. In this paper, this model and a parameter study using this model will be presented. The parameter study involves calculating the steady-state current output from the RTD as a function of an applied voltage drop across the RTD and also calculating the stability of that solution. To implement the parameter study, the computational model was connected to LOCA (Library of Continuation Algorithms), a part of Sandia National Laboratories parallel solver project, Trilinos. Numerical results will be presented.

Salinger, Andrew Gerhard; Zhao, P. (North Carolina State University, Raleigh, NC); Woolard, D. L. (U. S. Army Research Laboratory, NC); Kelley, C. Tim (North Carolina State University, Raleigh, NC); Lasater, Matthew S. (North Carolina State University, Raleigh, NC)

2005-03-01T23:59:59.000Z

463

Foam drilling simulator  

E-Print Network (OSTI)

Although the use of compressible drilling fluids is experiencing growth, the flow behavior and stability properties of drilling foams are more complicated than those of conventional fluids. In contrast with conventional mud, the physical properties of foam change along the wellbore. Foam physical and thermal properties are strongly affected by pressure and temperature. Many problems associated with field applications still exist, and a precise characterization of the rheological properties of these complex systems needs to be performed. The accurate determination of the foam properties in circulating wells helps to achieve better estimation of foam rheology and pressure. A computer code is developed to process the data and closely simulate the pressure during drilling a well. The model also offers a detailed discussion of many aspects of foam drilling operations and enables the user to generate many comparative graphs and tables. The effects of some important parameters such as: back-pressure, rate of penetration, cuttings concentration, cuttings size, and formation water influx on pressure, injection rate, and velocity are presented in tabular and graphical form. A discretized heat transfer model is formulated with an energy balance on a control volume in the flowing fluid. The finite difference model (FDM) is used to write the governing heat transfer equations in discretized form. A detailed discussion on the determination of heat transfer coefficients and the solution approach is presented. Additional research is required to analyze the foam heat transfer coefficient and thermal conductivity.

Paknejad, Amir Saman

2005-12-01T23:59:59.000Z

464

TERAPIXEL IMAGING OF COSMOLOGICAL SIMULATIONS  

SciTech Connect

The increasing size of cosmological simulations has led to the need for new visualization techniques. We focus on smoothed particle hydrodynamic (SPH) simulations run with the GADGET code and describe methods for visually accessing the entire simulation at full resolution. The simulation snapshots are rastered and processed on supercomputers into images that are ready to be accessed through a Web interface (GigaPan). This allows any scientist with a Web browser to interactively explore simulation data sets in both spatial and temporal dimensions and data sets which in their native format can be hundreds of terabytes in size or more. We present two examples, the first a static terapixel image of the MassiveBlack simulation, a P-GADGET SPH simulation with 65 billion particles, and the second an interactively zoomable animation of a different simulation with more than 1000 frames, each a gigapixel in size. Both are available for public access through the GigaPan Web interface. We also make our imaging software publicly available.

Feng Yu; Croft, Rupert A. C.; Di Matteo, Tiziana; Khandai, Nishikanta [Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Sargent, Randy; Nourbakhsh, Illah; Dille, Paul; Bartley, Chris [Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Springel, Volker [Heidelberger Institut fuer Theoretische Studien, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg (Germany); Jana, Anirban [Pittsburgh Supercomputing Center, Pittsburgh, PA 15213 (United States); Gardner, Jeffrey, E-mail: yfeng1@andrew.cmu.edu [Physics Department, University of Washington, Seattle, WA 98195 (United States)

2011-12-01T23:59:59.000Z

465

Les mots et les couleurs en mouvement  

E-Print Network (OSTI)

que sur le bleu clair. en bas de la loile el sur le lilas.progression \\'a de haut en bas, alors qu'au centre de ladislingue une progression de bas en haut Le bleu tres clair

Akli, Madalina

2004-01-01T23:59:59.000Z

466

Comparison of entrainment rates from a tank experiment with results using the one-dimensional turbulence model.  

Science Conference Proceedings (OSTI)

Recent work suggests that cloud effects remain one of the largest sources of uncertainty in model-based estimates of climate sensitivity. In particular, the entrainment rate in stratocumulus-topped mixed layers needs better models. More than thirty years ago a clever laboratory experiment was conducted by McEwan and Paltridge to examine an analog of the entrainment process at the top of stratiform clouds. Sayler and Breidenthal extended this pioneering work and determined the effect of the Richardson number on the dimensionless entrainment rate. The experiments gave hints that the interaction between molecular effects and the one-sided turbulence seems to be crucial for understanding entrainment. From the numerical point of view large-eddy simulation (LES) does not allow explicitly resolving all the fine scale processes at the entrainment interface. Direct numerical simulation (DNS) is limited due to the Reynolds number and is not the tool of choice for parameter studies. Therefore it is useful to investigate new modeling strategies, such as stochastic turbulence models which allow sufficient resolution at least in one dimension while having acceptable run times. We will present results of the One-Dimensional Turbulence stochastic simulation model applied to the experimental setup of Sayler and Breidenthal. The results on radiatively induced entrainment follow quite well the scaling of the entrainment rate with the Richardson number that was experimentally found for a set of trials. Moreover, we investigate the influence of molecular effects, the fluids optical properties, and the artifact of parasitic turbulence experimentally observed in the laminar layer. In the simulations the parameters are varied systematically for even larger ranges than in the experiment. Based on the obtained results a more complex parameterization of the entrainment rate than currently discussed in the literature seems to be necessary.

Kerstein, Alan R.; Sayler, B. J. (Black Hills State University, Spearfish, SD); Wunsch, S. (Johns Hopkins University, Laurel, MD); Schmidt, H. (BTU Cottbus, Siemens-Halske-Ring 14, 03046 Cottbus, Germany); Nedelec, R. (Ecole Centrale Marseille, Technopole de Chateau-Gombert, 13451 Marseille, France)

2010-05-01T23:59:59.000Z

467

BEST: Biochemical Engineering Simulation Technology  

DOE Green Energy (OSTI)

The idea of developing a process simulator that can describe biochemical engineering (a relatively new technology area) was formulated at the National Renewable Energy Laboratory (NREL) during the late 1980s. The initial plan was to build a consortium of industrial and U.S. Department of Energy (DOE) partners to enhance a commercial simulator with biochemical unit operations. DOE supported this effort; however, before the consortium was established, the process simulator industry changed considerably. Work on the first phase of implementing various fermentation reactors into the chemical process simulator, ASPEN/SP-BEST, is complete. This report will focus on those developments. Simulation Sciences, Inc. (SimSci) no longer supports ASPEN/SP, and Aspen Technology, Inc. (AspenTech) has developed an add-on to its ASPEN PLUS (also called BioProcess Simulator [BPS]). This report will also explain the similarities and differences between BEST and BPS. ASPEN, developed by the Massachusetts Institute of Technology for DOE in the late 1970s, is still the state-of-the-art chemical process simulator. It was selected as the only simulator with the potential to be easily expanded into the biochemical area. ASPEN/SP, commercially sold by SimSci, was selected for the BEST work. SimSci completed work on batch, fed-batch, and continuous fermentation reactors in 1993, just as it announced it would no longer commercially support the complete ASPEN/SP product. BEST was left without a basic support program. Luckily, during this same time frame, AspenTech was developing a biochemical simulator with its version of ASPEN (ASPEN PLUS), which incorporates most BEST concepts. The future of BEST will involve developing physical property data and models appropriate to biochemical systems that are necessary for good biochemical process design.

Not Available

1996-01-01T23:59:59.000Z

468

Simulation of Non-resonant Internal Kink Mode with Toroidal Rotation in NSTX  

SciTech Connect

Plasmas in spherical and conventional tokamaks, with weakly reversed shear q pro le and minimum q above but close to unity, are susceptible to an non-resonant (m, n ) = (1, 1) internal kink mode. This mode can saturate and persist and can induce a (2; 1) seed island for Neoclassical Tearing Mode (NTMs)1 . The mode can also lead to large energetic particle transport and signi cant broadening of beam-driven current. Motivated by these important e ects, we have carried out extensive nonlinear simulations of the mode with nite toroidal rotation using parameters and pro les of an NTSX plasma with a weakly reversed shear pro le. The numerical results show that, at the experimental level, plasma rotation has little e ect on either equilibrium or linear stability. However, rotation can signi cantly inuence the nonlinear dynamics of the (1, 1) mode and the the induced (2, 1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at nite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the e ects of rotation are found to greatly suppress the (2, 1) magnetic island even at a low level.

Fu, Guoyong

2013-07-16T23:59:59.000Z

469

Hybrid simulation models - When, Why, How?  

Science Conference Proceedings (OSTI)

Agent-Based Modeling and Simulation (ABMS) and System Dynamics (SD) are two popular simulation paradigms. Despite their common goal, these simulation methods are rarely combined and there has been a very low amount of joint research in these fields. ... Keywords: Agent-Based Modeling and Simulation, Artificial intelligence, Expert Systems, Hybrid simulation models, System Dynamics

Lauri Lttil; Per Hilletofth; Bishan Lin

2010-12-01T23:59:59.000Z

470

Mixed-Technology System-Level Simulation  

Science Conference Proceedings (OSTI)

This paper describes a computationally efficient method to simulate mixed-domain systems under the requirements of a system-level framework. The approach is the combined use of Modified Nodal Analysis (MNA) for the representation of a mixed-technology ... Keywords: MEM simulation, microsystem modeling and simulation, modified nodal analysis (MNA), optical MEM CAD tool, optoelectronic simulation, piecewise linear simulation (PWL)

J. A. Martinez; T. P. Kurzweg; S. P. Levitan; P. J. Marchand; D. M. Chiarulli

2001-10-01T23:59:59.000Z

471

Numerical wind speed simulation model  

DOE Green Energy (OSTI)

A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.

Ramsdell, J.V.; Athey, G.F.; Ballinger, M.Y.

1981-09-01T23:59:59.000Z

472

Validation of a Geothermal Simulator  

DOE Green Energy (OSTI)

A geothermal simulator, TETRAD, is validated against the Stanford Geothermal Problem Set. The governing equations, formulation, and solution technique employed by TETRAD are first outlined. Each problem in the Stanford Problem Set is then discussed in detail, and results from the simulations are presented. The results obtained using TETRAD are compared against several other geothermal simulators. Favorable comparison between results indicates that TETRAD is capable of solving the highly non-linear equations describing the flow of mass and energy in porous media. This validation exercise allows for the use of TETRAD in studying geothermal problems with a high degree of confidence.

Shook, G.M.; Faulder, D.D.

1991-10-01T23:59:59.000Z

473

ARM - Publications: Science Team Meeting Documents  

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

Large Eddy Simulations of Fair-Weather Cumulus Case at SGP Site Large Eddy Simulations of Fair-Weather Cumulus Case at SGP Site Zhu, P. and Albrecht, B.A., University of Miami Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting A fair-weather cumulus (FWC) case observed on July 6, 1997 at the ARM SGP site is simulated using RAMS model. In this study, we performed a series of numerical experiments to study the basic physics underlying the FWC and the evolution of these clouds in response to the change of external forcings and conditions. The simulations indicate that the evolution of shallow cumuli is very sensitive to the initial vertical structure of moisture and the variation of the entrainment moisture fluxes. Based on the penetration theory, we are able to develop a cloud initiation parameterization using

474

Applications of agent based simulation  

Science Conference Proceedings (OSTI)

This paper provides a survey and analysis of applications of Agent Based Simulation (ABS). A framework for describing and assessing the applications is presented and systematically applied. A general conclusion from the study is that even if ABS seems ...

Paul Davidsson; Johan Holmgren; Hans Kyhlbck; Dawit Mengistu; Marie Persson

2006-05-01T23:59:59.000Z

475

Simulation data as data streams  

Science Conference Proceedings (OSTI)

Computational or scientific simulations are increasingly being applied to solve a variety of scientific problems. Domains such as astrophysics, engineering, chemistry, biology, and environmental studies are benefiting from this important capability. ...

Ghaleb Abdulla; Terence Critchlow; William Arrighi

2004-03-01T23:59:59.000Z

476

Monte Carlo Simulation of Solidification  

Science Conference Proceedings (OSTI)

m>= (2+ cod).( l- cose)2. 4. (3). In the simulation, it is assumed that the nucleation in a cell (iJ) would not take place until the accumulation of nucleation (Ni)...

477

Computer Simulation Center in Internet  

E-Print Network (OSTI)

The general description of infrastructure and content of SciShop.ru computer simulation center is given. This resource is a new form of knowledge generation and remote education using modern Cloud Computing technologies.

Tarnavsky, G A

2011-01-01T23:59:59.000Z

478

Physics and detector simulation requirements  

Science Conference Proceedings (OSTI)

This document describes the computing environment needed to meet the requirements for high energy physics Monte Carlo Calculations for the simulation of Superconducting Super Collider Laboratory physics and detectors. (AIP)

Computer Acquisition Working Group

1990-01-01T23:59:59.000Z

479

Numerical Simulations of Maritime Frontogenesis  

Science Conference Proceedings (OSTI)

A hydrostatic primitive equation model initialized in a highly baroclinically unstable state was used to simulate maritime cyclogenesis and frontogenesis. In order to identify boundary layer physical processes important in maritime frontogenesis, ...

William T. Thompson; R. T. Williams

1997-01-01T23:59:59.000Z

480

Catching Carbon with Computer Simulations  

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

CRD and Material Sciences Researchers Receive 2 Million to Develop Efficient Carbon Capture Simulation Tools Contact: Linda Vu, lvu@lbl.gov , 510-495-2402 Share September 30,...

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

Factor Separation in Numerical Simulations  

Science Conference Proceedings (OSTI)

A simple method is developed for computing the interactions among various factors influencing the atmospheric circulations. It is shown how numerical simulations can be utilized to obtain the pure contribution of any factor to any predicted field,...

U. Stein; P. Alpert

1993-07-01T23:59:59.000Z

482

Robust simulation of lamprey tracking  

Science Conference Proceedings (OSTI)

Biologically realistic computer simulation of vertebrates is a challenging problem with exciting applications in computer graphics and robotics. Once the mechanics of locomotion are available it is interesting to mediate this locomotion with higher level ...

Matthew Beauregard; Paul J. Kennedy

2006-09-01T23:59:59.000Z

483

Simulation aids cogeneration system analysis  

Science Conference Proceedings (OSTI)

Cogeneration systems using gas turbines and heat-recovery steam generators (HRSGs) are widely used in chemical process industries (CPI) plants. Because these plants are quite expensive and the HRSG is an important part of the system, it is prudent to analyze the heat-recovery system or simulate its performance well in advance of finalizing plant specifications. Simulation is a method of predicting the performance of the HRSG under different operating modes and gas and steam conditions without physically designing the equipment. Such a study will provide the engineer with valuable information about the HRSG and its performance capabilities. The simulation results could influence the choice of steam system parameters and the selection of the steam or gas turbine. In addition, one may also obtain information about the performance of the HRSG and the cogeneration system. This article explains what HRSG simulation is and the basic methodology. Its applications are then illustrated through several examples.

Ganapathy, V.

1993-10-01T23:59:59.000Z

484

Confidence in ASCI scientific simulations  

SciTech Connect

The US Department of Energy`s (DOE) Accelerated Strategic Computing Initiative (ASCI) program calls for the development of high end computing and advanced application simulations as one component of a program to eliminate reliance upon nuclear testing in the US nuclear weapons program. This paper presents results from the ASCI program`s examination of needs for focused validation and verification (V and V). These V and V activities will ensure that 100 TeraOP-scale ASCI simulation code development projects apply the appropriate means to achieve high confidence in the use of simulations for stockpile assessment and certification. The authors begin with an examination of the roles for model development and validation in the traditional scientific method. The traditional view is that the scientific method has two foundations, experimental and theoretical. While the traditional scientific method does not acknowledge the role for computing and simulation, this examination establishes a foundation for the extension of the traditional processes to include verification and scientific software development that results in the notional framework known as Sargent`s Framework. This framework elucidates the relationships between the processes of scientific model development, computational model verification and simulation validation. This paper presents a discussion of the methodologies and practices that the ASCI program will use to establish confidence in large-scale scientific simulations. While the effort for a focused program in V and V is just getting started, the ASCI program has been underway for a couple of years. The authors discuss some V and V activities and preliminary results from the ALEGRA simulation code that is under development for ASCI. The breadth of physical phenomena and the advanced computational algorithms that are employed by ALEGRA make it a subject for V and V that should typify what is required for many ASCI simulations.

Ang, J.A.; Trucano, T.G. [Sandia National Labs., Albuquerque, NM (United States); Luginbuhl, D.R. [Dept. of Energy, Washington, DC (United States)

1998-06-01T23:59:59.000Z

485

Efficient simulation-based discrete optimization  

Science Conference Proceedings (OSTI)

In many practical applications of simulation it is desirable to optimize the levels of integer or binary variables that are inputs for the simulation model. In these cases, the objective function must often be estimated through an expensive simulation ...

Seth D. Guikema; Rachel A. Davidson; Zehra a?nan

2004-12-01T23:59:59.000Z

486

System dynamics simulation of the telecom industry  

E-Print Network (OSTI)

The primary goal of this research effort was to integrate several pieces of relatively simple dynamics simulations into a full blown system dynamics simulation of the telecom industry. The economic simulation model was ...

Shapira, Gil, 1971-

2004-01-01T23:59:59.000Z

487

Proceedings of the Winter Simulation Conference  

Science Conference Proceedings (OSTI)

Welcome to the 2012 Winter Simulation Conference (WSC), recognized as the premiere international conference for simulation professionals in discrete and combined discrete-continuous simulation. Our venue of Berlin this year continues the trend of new ...

Oliver Rose; Adelinde M. Uhrmacher

2012-12-01T23:59:59.000Z

488

An advanced fuel cell simulator  

E-Print Network (OSTI)

Fuel cell power generation systems provide a clean alternative to the conventional fossil fuel based systems. Fuel cell systems have a high e?ciency and use easily available hydrocarbons like methane. Moreover, since the by-product is water, they have a very low environmental impact. The fuel cell system consists of several subsystems requiring a lot of e?ort from engineers in diverse areas. Fuel cell simulators can provide a convenient and economic alternative for testing the electrical subsystems such as converters and inverters. This thesis proposes a low-cost and an easy-to-use fuel cell simulator using a programmable DC supply along with a control module written in LabVIEW. This simulator reproduces the electrical characteristics of a 5kW solid oxide fuel cell (SOFC) stack under various operating conditions. The experimental results indicate that the proposed simulator closely matches the voltage-current characteristic of the SOFC system under varying load conditions. E?ects of non-electrical parameters like hydrogen ?ow rate are also modeled and these parameters are taken as dynamic inputs from the user. The simulator is customizable through a graphical user interface and allows the user to model other types of fuel cells with the respective voltage-current data. The simulator provides an inexpensive and accurate representation of a solid oxide fuel cell under steady state and transient conditions and can replace an actual fuel cell during testing of power conditioning equipment.

Acharya, Prabha Ramchandra

2004-08-01T23:59:59.000Z

489

Zero Power Reactor simulation | Argonne National Laboratory  

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

Zero Power Reactor simulation Share Description Ever wanted to see a nuclear reactor core in action? Here's a detailed simulation of the Zero Power Reactor experiment, run by...

490

MAPPING HVAC SYSTEMS FOR SIMULATION IN ENERGYPLUS  

E-Print Network (OSTI)

LBNL-XXXXX MAPPING HVAC SYSTEMS FOR SIMULATION IN ENERGYPLUSof California. MAPPING HVAC SYSTEMS FOR SIMULATION INpresent a conventional view of HVAC systems to the user, and

Basarkar, Mangesh

2013-01-01T23:59:59.000Z

491

Simulating Complex Window Systems using BSDF Data  

E-Print Network (OSTI)

Simulating Complex Window Systems using BSDF Data MariaJune 2009 Simulating Complex Window Systems using BSDF Datathe performance of conventional window systems. Complex

Konstantoglou, Maria

2011-01-01T23:59:59.000Z

492

Computer-Simulation-Assisted Lean Manufacturing Training.  

E-Print Network (OSTI)

??This thesis assesses the potential of using computer simulation to aid existing lean manufacturing training methods such as lecture and live simulation. An investigation of (more)

Wang, Luoding 1970-

2005-01-01T23:59:59.000Z

493

Theory, Modeling & Simulation | More Science | ORNL  

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

Theory, Modeling and Simulation SHARE Theory, Modeling and Simulation ORNL conducts a broad range of theoretical research in the physical sciences with over 60 staff members and...

494

Theory, Modeling & Simulation | More Science | ORNL  

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

Materials Theory and Simulation SHARE Materials Theory and Simulation ORNL conducts a broad range of theoretical research in the physical sciences with over 60 staff members and...

495

Building Technologies Office: House Simulation Protocols Report  

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

House Simulation House Simulation Protocols Report to someone by E-mail Share Building Technologies Office: House Simulation Protocols Report on Facebook Tweet about Building Technologies Office: House Simulation Protocols Report on Twitter Bookmark Building Technologies Office: House Simulation Protocols Report on Google Bookmark Building Technologies Office: House Simulation Protocols Report on Delicious Rank Building Technologies Office: House Simulation Protocols Report on Digg Find More places to share Building Technologies Office: House Simulation Protocols Report on AddThis.com... About Take Action to Save Energy Partner With DOE Activities Solar Decathlon Building America Research Innovations Research Tools Building Science Education Climate-Specific Guidance Solution Center

496

A Simulator for Timed CSP  

E-Print Network (OSTI)

Time is an integral aspect of computer systems. It is essential for modelling a systems performance, but may also affect its safety or security. Timed CSP [Sch00] conservatively extends the process algebra CSP with timed primitives, where real numbers ? 0 model how time passes with reference to a single, conceptually global, clock. While there have been approaches for model checking Timed CSP ([Sch00, DHSZ06]), to the best of our knowledge we are the first to present a simulator for Timed CSP. Here, we restrict time to rational values only. Theoretically, this limits the expressibility of the language. Practically, this limitation turns out to be negligible (for instance all examples of Schneiders book [Sch00] can be dealt with in our simulator). The simulator is the outcome of an undergraduate project at Swansea University [Dra11]. Our Timed CSP simulator extends the open source tool ProB [Leu]. ProBs CSP simulator works as follows: The CSP specification is analyzed by a parser (written in Haskell) and translated to a representation in Prolog. A CSP Interpreter (in Prolog) stores the firing rules of CSPs operational semantics. The Simulator (also in Prolog) determines the actions available and the resultant states. A GUI (written in Tcl/Tk) allows the user to interact with the Simulator. Timed CSP is closed under rational time [DNR11]. Consider, for example, the following firing rule ( t ? stands for a timed transition of duration t): P d? ? P ? (P ?d Q) d?

Marc Dragon; Andy Gimblett; Markus Roggenbach; Jens Bendisposto; Cliff Jones; Michael Leuschel; Er Romanovsky; Tiziana Margaria; Julia Padberg; Gabriele Taentzer; Marc Dragon; Andy Gimblett; Markus Roggenbach

2011-01-01T23:59:59.000Z

497

Stochastic models: theory and simulation.  

SciTech Connect

Many problems in applied science and engineering involve physical phenomena that behave randomly in time and/or space. Examples are diverse and include turbulent flow over an aircraft wing, Earth climatology, material microstructure, and the financial markets. Mathematical models for these random phenomena are referred to as stochastic processes and/or random fields, and Monte Carlo simulation is the only general-purpose tool for solving problems of this type. The use of Monte Carlo simulation requires methods and algorithms to generate samples of the appropriate stochastic model; these samples then become inputs and/or boundary conditions to established deterministic simulation codes. While numerous algorithms and tools currently exist to generate samples of simple random variables and vectors, no cohesive simulation tool yet exists for generating samples of stochastic processes and/or random fields. There are two objectives of this report. First, we provide some theoretical background on stochastic processes and random fields that can be used to model phenomena that are random in space and/or time. Second, we provide simple algorithms that can be used to generate independent samples of general stochastic models. The theory and simulation of random variables and vectors is also reviewed for completeness.

Field, Richard V., Jr.

2008-03-01T23:59:59.000Z

498

Radiation in molecular dynamic simulations  

DOE Green Energy (OSTI)

Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The new technique passes a key test: it relaxes to a blackbody spectrum for a plasma in local thermodynamic equilibrium. This new tool also provides a method for assessing the accuracy of energy and momentum exchange models in hot dense plasmas. As an example, we simulate the evolution of non-equilibrium electron, ion, and radiation temperatures for a hydrogen plasma using the new molecular dynamics simulation capability.

Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M

2008-10-13T23:59:59.000Z

499

Simulating chemistry using quantum computers  

E-Print Network (OSTI)

The difficulty of simulating quantum systems, well-known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.

Ivan Kassal; James D. Whitfield; Alejandro Perdomo-Ortiz; Man-Hong Yung; Aln Aspuru-Guzik

2010-07-15T23:59:59.000Z

500

Heat Recovery Steam Generator Simulation  

E-Print Network (OSTI)

The paper discusses the applications of Heat Recovery Steam Generator Simulation. Consultants, plant engineers and plant developers can evaluate the steam side performance of HRSGs and arrive at the optimum system which matches the needs of the process plant, cogeneration or combined cycle plant. There is no need to design the HRSG per se and hence simulation is a valuable tool for anyone interested in evaluating the HRSG performance even before it is designed. It can also save a lot of time for specification writers as they need not guess how the steam side performance will vary with different gas/steam parameters. A few examples are given to show how simulation methods can be applied to real life problems.

Ganapathy, V.

1993-03-01T23:59:59.000Z