National Library of Energy BETA

Sample records for large-eddy simulation les

  1. Sandia Energy - Large Eddy Simulation (LES) of Engines

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

    Large Eddy Simulation (LES) of Engines Home Transportation Energy Predictive Simulation of Engines Engine Combustion Modeling Large Eddy Simulation (LES) of Engines Large Eddy...

  2. Large Eddy Simulation (LES) of Engines

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

    Reacting FlowModelingLarge Eddy Simulation (LES) of ... The integrated set of tasks provides an optimal combination ... models for a variety of propulsion and power devices

  3. Large Eddy Simulation (LES) of Engines

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

    Engine Combustion/Modeling/Large Eddy Simulation (LES) of Engines Large Eddy Simulation (LES) of Engines admin 2015-10-28T02:19:26+00:00 LES-SN-LES-Eng-Combustion-Modeling-2 The combination of High Performance Computing (HPC) and the Large Eddy Simulation (LES) technique has significant potential to provide new insights into the dynamics of IC-engine flow processes. At the CRF, we integrate the combined merits of HPC and LES in a manner that provides some of the highest-fidelity, most detailed

  4. Large Eddy Simulation (LES) of Engines

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

    Reacting Flow/Modeling/Large Eddy Simulation (LES) of Engines Large Eddy Simulation (LES) of Engines admin 2015-10-30T01:57:44+00:00 The combination of high-performance computing (HPC) and the large eddy simulation (LES) technique has significant potential to provide new insights into the dynamics of many types of turbulent combustion processes. The objective of LES development at the CRF is to fully integrate the combined merits of HPC and LES in a manner that provides some of the

  5. Large Eddy Simulation (LES) Applied to Advanced Engine Combustion...

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

    Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine Combustion Research Vehicle ...

  6. Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine...

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

    ace007oefelein2010o.pdf More Documents & Publications Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine Combustion Research Large Eddy Simulation (LES)...

  7. Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel...

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

    More Documents & Publications Large Eddy Simulation (LES) Applied to LTCDieselHydrogen Engine Combustion Research Large Eddy Simulation (LES) Applied to Advanced Engine ...

  8. Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine...

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

    More Documents & Publications Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine Combustion Research Large Eddy Simulation (LES) Applied to LTCDiesel...

  9. Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine

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

    Combustion Research | Department of Energy ace_07_oefelein.pdf (4.03 MB) More Documents & Publications Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine Combustion Research Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine Combustion Research Vehicle Technologies Office Merit Review 2014: Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Combustion Research | Department of Energy

    1 DOE Hydrogen and Fuel Cells Program,

  10. Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine

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

    Combustion Research | Department of Energy Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine Combustion Research Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine Combustion Research 2009 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. ace_07_oefelein.pdf (4.03 MB) More Documents & Publications Large Eddy Simulation (LES) Applied to Low-Temperature and Diesel Engine

  11. Large Eddy Simulations: Where

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

    Eddy Simulations: Where observations and modeling collides July 18, 2015 Cascade of Models ⌅ General Circulation Models ⌅ Regional Models ⌅ Large-Eddy Simulations ⌅ Direct Numerical Simulations LES GCM vs LES History Theory What if? Using LES together with Observations Testbed LES 2 / 37 Cascade of Models General Circulation Models ⌅ Domain size: Entire Earth ⌅ Horizontal Boundary conditions: None ⌅ Horizontal grid spacing: 50km ⌅ Total number of points: about 400 ⇥ 400 ⇥ 100

  12. Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation...

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

    Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation (LES) Applied to Advanced Engine ...

  13. Gyrokinetic large eddy simulations

    SciTech Connect (OSTI)

    Morel, P.; Navarro, A. Banon; Albrecht-Marc, M.; Carati, D.; Merz, F.; Goerler, T.; Jenko, F.

    2011-07-15

    The large eddy simulation approach is adapted to the study of plasma microturbulence in a fully three-dimensional gyrokinetic system. Ion temperature gradient driven turbulence is studied with the GENE code for both a standard resolution and a reduced resolution with a model for the sub-grid scale turbulence. A simple dissipative model for representing the effect of the sub-grid scales on the resolved scales is proposed and tested. Once calibrated, the model appears to be able to reproduce most of the features of the free energy spectra for various values of the ion temperature gradient.

  14. Vehicle Technologies Office Merit Review 2015: Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research

    Broader source: Energy.gov [DOE]

    Presentation given by Sandia National Laboratories at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about Large Eddy...

  15. Vehicle Technologies Office Merit Review 2014: Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research

    Broader source: Energy.gov [DOE]

    Presentation given by Sandia National Laboratories at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about large eddy...

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

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

  17. Large-eddy simulation of turbulent circular jet flows

    SciTech Connect (OSTI)

    Jones, S. C.; Sotiropoulos, F.; Sale, M. J.

    2002-07-01

    This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energys Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.

  18. Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership

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

    Computing Facility droplets. Large Eddy Simulations of a GE CFM combustor, temperature distribution and liquid fuel droplets. Anne Dord, GE Global Research Large Eddy Simulations of Combustor Liner Flows PI Name: Anne Dord PI Email: anne.dord@ge.com Institution: GE Global Research Allocation Program: INCITE Allocation Hours at ALCF: 75 Million Year: 2014 Research Domain: Engineering Aviation gas turbine engines are an essential part of the transportation industry. In 2012, the commercial

  19. Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership

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

    Computing Facility droplets Large Eddy Simulations of a GE CFM combustor, temperature distribution and liquid fuel droplets. Credit: Anne Dord, GE Global Research Large Eddy Simulations of Combustor Liner Flows PI Name: Anne Dord PI Email: anne.dord@ge.com Institution: GE Global Research Allocation Program: INCITE Allocation Hours at ALCF: 89 Million Year: 2015 Research Domain: Engineering In 2012, the commercial aviation industry spent an estimated $207 billion on fuel, or about 33 percent

  20. Large-Eddy Simulation of Wind-Plant Aerodynamics: Preprint

    SciTech Connect (OSTI)

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

    2012-01-01

    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.

  1. Mesoscale and Large-Eddy Simulations for Wind Energy

    SciTech Connect (OSTI)

    Marjanovic, N

    2011-02-22

    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.

  2. Large eddy simulation of unsteady lean stratified premixed combustion

    SciTech Connect (OSTI)

    Duwig, C.; Fureby, C.

    2007-10-15

    Premixed turbulent flame-based technologies are rapidly growing in importance, with applications to modern clean combustion devices for both power generation and aeropropulsion. However, the gain in decreasing harmful emissions might be canceled by rising combustion instabilities. Unwanted unsteady flame phenomena that might even destroy the whole device have been widely reported and are subject to intensive studies. In the present paper, we use unsteady numerical tools for simulating an unsteady and well-documented flame. Computations were performed for nonreacting, perfectly premixed and stratified premixed cases using two different numerical codes and different large-eddy-simulation-based flamelet models. Nonreacting simulations are shown to agree well with experimental data, with the LES results capturing the mean features (symmetry breaking) as well as the fluctuation level of the turbulent flow. For reacting cases, the uncertainty induced by the time-averaging technique limited the comparisons. Given an estimate of the uncertainty, the numerical results were found to reproduce well the experimental data in terms both of mean flow field and of fluctuation levels. In addition, it was found that despite relying on different assumptions/simplifications, both numerical tools lead to similar predictions, giving confidence in the results. Moreover, we studied the flame dynamics and particularly the response to a periodic pulsation. We found that above a certain excitation level, the flame dynamic changes and becomes rather insensitive to the excitation/instability amplitude. Conclusions regarding the self-growth of thermoacoustic waves were drawn. (author)

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

    SciTech Connect (OSTI)

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

    2008-09-08

    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.

  4. Large Eddy Simulations of Combustor Liner Flows | Argonne Leadership

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

    Computing Facility Turbulent flow going through a multi-hole coupon geometry Turbulent flow going through a multi-hole coupon geometry. Density iso surface colored by velocity magnitude. Joseph Insley, Argonne National Laboratory; Lee Shunn, Cascade Technologies; Anne Dord, GE Aviation; and Yonduck Sung, GE Global Research Large Eddy Simulations of Combustor Liner Flows PI Name: Anne Dord PI Email: anne.dord@ge.com Institution: GE Aviation Allocation Program: INCITE Allocation Hours at ALCF:

  5. A Novel Approach to Wall Model Treatment for Large Eddy Simulations...

    Office of Scientific and Technical Information (OSTI)

    A Novel Approach to Wall Model Treatment for Large Eddy Simulations. Citation Details In-Document Search Title: A Novel Approach to Wall Model Treatment for Large Eddy Simulations. ...

  6. Large-Eddy Simulation of the Bachalo-Johnson Flow, with Shock-Induced

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

    Separation | Argonne Leadership Computing Facility Instantaneous numerical Schlieren (contours of magnitude of the density gradient) from wall-modeled LES (WMLES) of the transonic Gaussian-shaped 2D bump on a flat plate. Coordinates are given in meters. Credit: Kirill Belyaev, Andrey Garbaruk, Michael Shur, Michael Strelets, and Andrey Travin, New Technologies and Services, Ltd. Large-Eddy Simulation of the Bachalo-Johnson Flow, with Shock-Induced Separation PI Name: Philippe Spalart PI

  7. A Novel Approach to Wall Model Treatment for Large Eddy Simulations

    Office of Scientific and Technical Information (OSTI)

    in the national interest Sandia National Laboratories A Novel Approach to Wall Model Treatment for Large Eddy Simulations Myra Blaylock Sandia National Laboratories is a ...

  8. Intercomparison of Large-eddy Simulations of Arctic Mixed-phase...

    Office of Scientific and Technical Information (OSTI)

    Intercomparison of Large-eddy Simulations of Arctic Mixed-phase Clouds: Importance of Ice Size Distribution Assumptions Citation Details In-Document Search Title: Intercomparison ...

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

    SciTech Connect (OSTI)

    Sondak, David; Oberai, Assad A.

    2012-10-15

    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.

  10. Large eddy simulation of forced ignition of an annular bluff-body burner

    SciTech Connect (OSTI)

    Subramanian, V.; Domingo, P.; Vervisch, L.

    2010-03-15

    The optimization of the ignition process is a crucial issue in the design of many combustion systems. Large eddy simulation (LES) of a conical shaped bluff-body turbulent nonpremixed burner has been performed to study the impact of spark location on ignition success. This burner was experimentally investigated by Ahmed et al. [Combust. Flame 151 (2007) 366-385]. The present work focuses on the case without swirl, for which detailed measurements are available. First, cold-flow measurements of velocities and mixture fractions are compared with their LES counterparts, to assess the prediction capabilities of simulations in terms of flow and turbulent mixing. Time histories of velocities and mixture fractions are recorded at selected spots, to probe the resolved probability density function (pdf) of flow variables, in an attempt to reproduce, from the knowledge of LES-resolved instantaneous flow conditions, the experimentally observed reasons for success or failure of spark ignition. A flammability map is also constructed from the resolved mixture fraction pdf and compared with its experimental counterpart. LES of forced ignition is then performed using flamelet fully detailed tabulated chemistry combined with presumed pdfs. Various scenarios of flame kernel development are analyzed and correlated with typical flow conditions observed in this burner. The correlations between, velocities and mixture fraction values at the sparking time and the success or failure of ignition, are then further discussed and analyzed. (author)

  11. Applications of large-eddy simulation: Synthesis of neutral boundary layer models

    SciTech Connect (OSTI)

    Ohmstede, W.D.

    1987-12-01

    The object of this report is to describe progress made towards the application of large-eddy simulation (LES), in particular, to the study of the neutral boundary layer (NBL). The broad purpose of the study is to provide support to the LES project currently underway at LLNL. The specific purpose of this study is to lay the groundwork for the simulation of the SBL through the establishment and implementation of model criteria for the simulation of the NBL. The idealistic NBL is never observed in the atmosphere and therefore has little practical significance. However, it is of considerable theoretical interest for several reasons. The report discusses the concept of Rossby-number similarity theory as it applies to the NBL. A particular implementation of the concept is described. Then, the results from prior simulations of the NBL are summarized. Model design criteria for two versions of the Brost LES (BLES) model are discussed. The general guidelines for the development of Version 1 of the Brost model (BV1) were to implement the model with a minimum of modifications which would alter the design criteria as established by Brost. Two major modifications of BLES incorporated into BV1 pertain to the initialization/parameterization of the model and the generalization of the boundary conditions at the air/earth interface. 18 refs., 4 figs.

  12. Improving Parameterization of Entrainment Rate for Shallow Convection with Aircraft Measurements and Large-Eddy Simulation

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

    Lu, Chunsong; Liu, Yangang; Zhang, Guang J.; Wu, Xianghua; Endo, Satoshi; Cao, Le; Li, Yueqing; Guo, Xiaohao

    2016-02-01

    This work examines the relationships of entrainment rate to vertical velocity, buoyancy, and turbulent dissipation rate by applying stepwise principal component regression to observational data from shallow cumulus clouds collected during the Routine AAF [Atmospheric Radiation Measurement (ARM) Aerial Facility] Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site near Lamont, Oklahoma. The cumulus clouds during the RACORO campaign simulated using a large eddy simulation (LES) model are also examined with the same approach. The analysis shows that a combination of multiple variables can better represent entrainment ratemore » in both the observations and LES than any single-variable fitting. Three commonly used parameterizations are also tested on the individual cloud scale. A new parameterization is therefore presented that relates entrainment rate to vertical velocity, buoyancy and dissipation rate; the effects of treating clouds as ensembles and humid shells surrounding cumulus clouds on the new parameterization are discussed. Physical mechanisms underlying the relationships of entrainment rate to vertical velocity, buoyancy and dissipation rate are also explored.« less

  13. Investigation of Rossby-number similarity in the neutral boundary layer using large-eddy simulation

    SciTech Connect (OSTI)

    Ohmstede, W.D.; Cederwall, R.T.; Meyers, R.E.

    1988-01-01

    One special case of particular interest, especially to theoreticians, is the steady-state, horizontally homogeneous, autobarotropic (PLB), hereafter referred to as the neutral boundary layer (NBL). The NBL is in fact a 'rare' atmospheric phenomenon, generally associated with high-wind situations. Nevertheless, there is a disproportionate interest in this problem because Rossby-number similarity theory provides a sound approach for addressing this issue. Rossby-number similarity theory has rather wide acceptance, but because of the rarity of the 'true' NBL state, there remains an inadequate experimental database for quantifying constants associated with the Rossby-number similarity concept. Although it remains a controversial issue, it has been proposed that large-eddy simulation (LES) is an alternative to physical experimentation for obtaining basic atmospherc 'data'. The objective of the study reported here is to investigate Rossby-number similarity in the NBL using LES. Previous studies have not addressed Rossby-number similarity explicitly, although they made use of it in the interpretation of their results. The intent is to calculate several sets of NBL solutions that are ambiguous relative to the their respective Rossby numbers and compare the results for similarity, or the lack of it. 14 refs., 1 fig.

  14. Practical application of large eddy simulation to film cooling flow analysis on gas turbine airfoils

    SciTech Connect (OSTI)

    Takata, T.; Takeishi, K.; Kawata, Y.; Tsuge, A.

    1999-07-01

    Large eddy simulation (LES) using body-fitted coordinates is applied to solve film cooling flow on turbine blades. The turbulent model was tuned using the experimental flow field and adiabatic film cooling effectiveness measurements for a single row of holes on a flat plate surface. The results show the interaction between the main stream boundary layer and injected film cooling air generates kidney and horseshoe shaped vortices. Comparison of the temperature distribution between experimental results and present analysis has been conducted. The non-dimensional temperature distribution at x/d = 1 is dome style and quantitatively agrees with experimental results. LES was also applied to solve film cooling on a turbine airfoil. If LES was applied to solve whole flow field domain large CPU time would make the solution impractical. LES, using body-fitted coordinates, is applied to solve the non-isotropic film cooling flow near the turbine blade. The cascade flow domain, with a pitch equal to one film cooling hole spacing, is solved using {kappa}-{epsilon} model. By using such a hybrid numerical method, CPU time is reduced and numerical accuracy is insured. The analytical results show the interaction between the flow blowing through film cooling holes and mainstream on the suction and pressure surfaces of the turbine airfoil. They also show the fundamental structure of the film cooling air flow is governed by arch internal secondary flow and horseshoe vortices which have a similar structure to film cooling air flow blowing through a cooling hole on a flat plate. In the flow field, the effect of turbulent structure on curvature (relaminarization) and flow pattern, involving the interaction between main flow and the cooling jet, are clearly shown. Film cooling effectiveness on the blade surface is predicted from the results of the thermal field calculation and is compared with the test result.

  15. Modifications to WRFs dynamical core to improve the treatment of moisture for large-eddy simulations

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

    Xiao, Heng; Endo, Satoshi; Wong, May; Skamarock, William C.; Klemp, Joseph B.; Fast, Jerome D.; Gustafson, Jr., William I.; Vogelmann, Andrew; Wang, Hailong; Liu, Yangang; et al

    2015-10-29

    Yamaguchi and Feingold (2012) note that the cloud fields in their large-eddy simulations (LESs) of marine stratocumulus using the Weather Research and Forecasting (WRF) model exhibit a strong sensitivity to time stepping choices. In this study, we reproduce and analyze this sensitivity issue using two stratocumulus cases, one marine and one continental. Results show that (1) the sensitivity is associated with spurious motions near the moisture jump between the boundary layer and the free atmosphere, and (2) these spurious motions appear to arise from neglecting small variations in water vapor mixing ratio (qv) in the pressure gradient calculation in themore » acoustic sub-stepping portion of the integration procedure. We show that this issue is remedied in the WRF dynamical core by replacing the prognostic equation for the potential temperature θ with one for the moist potential temperature θm=θ(1+1.61qv), which allows consistent treatment of moisture in the calculation of pressure during the acoustic sub-steps. With this modification, the spurious motions and the sensitivity to the time stepping settings (i.e., the dynamic time step length and number of acoustic sub-steps) are eliminated in both of the example stratocumulus cases. In conclusion, this modification improves the applicability of WRF for LES applications, and possibly other models using similar dynamical core formulations, and also permits the use of longer time steps than in the original code.« less

  16. Modifications to WRFs dynamical core to improve the treatment of moisture for large-eddy simulations

    SciTech Connect (OSTI)

    Xiao, Heng; Endo, Satoshi; Wong, May; Skamarock, William C.; Klemp, Joseph B.; Fast, Jerome D.; Gustafson, Jr., William I.; Vogelmann, Andrew; Wang, Hailong; Liu, Yangang; Lin, Wuyin

    2015-10-29

    Yamaguchi and Feingold (2012) note that the cloud fields in their large-eddy simulations (LESs) of marine stratocumulus using the Weather Research and Forecasting (WRF) model exhibit a strong sensitivity to time stepping choices. In this study, we reproduce and analyze this sensitivity issue using two stratocumulus cases, one marine and one continental. Results show that (1) the sensitivity is associated with spurious motions near the moisture jump between the boundary layer and the free atmosphere, and (2) these spurious motions appear to arise from neglecting small variations in water vapor mixing ratio (qv) in the pressure gradient calculation in the acoustic sub-stepping portion of the integration procedure. We show that this issue is remedied in the WRF dynamical core by replacing the prognostic equation for the potential temperature θ with one for the moist potential temperature θm=θ(1+1.61qv), which allows consistent treatment of moisture in the calculation of pressure during the acoustic sub-steps. With this modification, the spurious motions and the sensitivity to the time stepping settings (i.e., the dynamic time step length and number of acoustic sub-steps) are eliminated in both of the example stratocumulus cases. In conclusion, this modification improves the applicability of WRF for LES applications, and possibly other models using similar dynamical core formulations, and also permits the use of longer time steps than in the original code.

  17. Large Eddy Simulation of Two-Phase Flow Combustion in Gas Turbines |

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

    Argonne Leadership Computing Facility Fields of temperature and pressure in a simulation of a complete helicopter combustion chamber performed on the IBM Blue Gene/P at the ALCF (July 2010). Large Eddy Simulation of Two-Phase Flow Combustion in Gas Turbines PI Name: Thierry Poinsot PI Email: poinsot@cerfacs.fr Institution: CERFACS Allocation Program: INCITE Allocation Hours at ALCF: 8 Million Year: 2010 Research Domain: Chemistry The increase of computer power has allowed science to make

  18. Large Eddy Simulation of two phase flow combustion in gas turbines |

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

    Argonne Leadership Computing Facility Simulation of two phase flow combustion in gas turbines PI Name: Thierry Poinsot PI Email: poinsot@cerfacs.fr Institution: CERFACS Allocation Program: INCITE Allocation Hours at ALCF: 10,000,000 Year: 2011 Research Domain: Chemistry Research in CombustiLETFLOC (Large Eddy Simulation of two phase flow combustion in gas turbines) aims at improving our knowledge of two phase flows and their combustion in gas turbines. This will allow a better assesment of

  19. Large-Eddy Simulation of Two-Phase Flow Combustion in Gas Turbines |

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

    Argonne Leadership Computing Facility Large-Eddy Simulation of Two-Phase Flow Combustion in Gas Turbines PI Name: Thierry Poinsot PI Email: poinsot@cerfacs.fr Institution: CERFACS Allocation Program: INCITE Allocation Hours at ALCF: 10,000,000 Year: 2012 Research Domain: Chemistry Using the capability of the Blue Gene/P supercomputer, CERFACS has been performing top-of-the-line, quality simulations on highly complex cases to numerically model a real combustor. The project focuses on Large

  20. Large Eddy Simulation of Wind Turbine Wakes. Detailed Comparisons of Two Codes Focusing on Effects of Numerics and Subgrid Modeling

    SciTech Connect (OSTI)

    Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles

    2015-06-18

    In this work we report on results from a detailed comparative numerical study from two Large Eddy Simulation (LES) codes using the Actuator Line Model (ALM). The study focuses on prediction of wind turbine wakes and their breakdown when subject to uniform inflow. Previous studies have shown relative insensitivity to subgrid modeling in the context of a finite-volume code. The present study uses the low dissipation pseudo-spectral LES code from Johns Hopkins University (LESGO) and the second-order, finite-volume OpenFOAMcode (SOWFA) from the National Renewable Energy Laboratory. When subject to uniform inflow, the loads on the blades are found to be unaffected by subgrid models or numerics, as expected. The turbulence in the wake and the location of transition to a turbulent state are affected by the subgrid-scale model and the numerics.

  1. Large Eddy Simulation of Wind Turbine Wakes. Detailed Comparisons of Two Codes Focusing on Effects of Numerics and Subgrid Modeling

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

    Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles

    2015-06-18

    In this work we report on results from a detailed comparative numerical study from two Large Eddy Simulation (LES) codes using the Actuator Line Model (ALM). The study focuses on prediction of wind turbine wakes and their breakdown when subject to uniform inflow. Previous studies have shown relative insensitivity to subgrid modeling in the context of a finite-volume code. The present study uses the low dissipation pseudo-spectral LES code from Johns Hopkins University (LESGO) and the second-order, finite-volume OpenFOAMcode (SOWFA) from the National Renewable Energy Laboratory. When subject to uniform inflow, the loads on the blades are found to bemore » unaffected by subgrid models or numerics, as expected. The turbulence in the wake and the location of transition to a turbulent state are affected by the subgrid-scale model and the numerics.« less

  2. Large eddy simulation of mixing between hot and cold sodium flows - comparison with experiments

    SciTech Connect (OSTI)

    Simoneau, J.P.; Noe, H.; Menant, B.

    1995-09-01

    The large eddy simulation is becoming a potential powerful tool for the calculation of turbulent flows. In nuclear liquid metal cooled fast reactors, the knowledge of the turbulence characteristics is of great interest for the prediction and the analysis of thermal stripping phenomena. The objective of this paper is to give a contribution in the evaluation of the large eddy simulation technique is an individual case. The problem chosen is the case of the mixing between hot and cold sodium flows. The computations are compared with available sodium tests. This study shows acceptable qualitative results but the simple model used is not able to predict the turbulence characteristics. More complex models including larger domains around the fluctuating zone and fluctuating boundary conditions could be necessary. Validation works are continuing.

  3. Large Eddy Simulation of PBL Stratocumulus: Comparison of Multi-Dimensional and IPA Longwave Radiative Forcing

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

    Large-Eddy Simulation of PBL Stratocumulus: Comparison 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, Oklahoma M. Ovtchinnikov Pacific Northwest National Laboratory A. B. Davis Los Alamos National Laboratory Los Alamos, New Mexico R. R. Cahalan National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland E. E. Takara and R. G. Ellingson

  4. Large-Eddy Simulations of Contrail-to-Cirrus Transition | Argonne

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

    Leadership Computing Facility Large-Eddy Simulations of Contrail-to-Cirrus Transition PI Name: Roberto Paoli PI Email: paoli@cerfacs.fr Institution: CERFACS Allocation Program: INCITE Allocation Hours at ALCF: 20,000,000 Year: 2012 Research Domain: Earth Science Aircraft emissions can affect the chemical composition of the atmosphere and modify or create additional ice clouds in the form of contrails. When contrails spread to form cirrus clouds, they can persist for hours and extend over

  5. Development of Quality Assessment Techniques for Large Eddy Simulation of Propulsion and Power Systems in Complex Geometries

    SciTech Connect (OSTI)

    Lacaze, Guilhem; Oefelein, Joseph

    2015-03-01

    Large-eddy-simulation (LES) is quickly becoming a method of choice for studying complex thermo-physics in a wide range of propulsion and power systems. It provides a means to study coupled turbulent combustion and flow processes in parameter spaces that are unattainable using direct-numerical-simulation (DNS), with a degree of fidelity that can be far more accurate than conventional engineering methods such as the Reynolds-averaged Navier-Stokes (RANS) approx- imation. However, development of predictive LES is complicated by the complex interdependence of different type of errors coming from numerical methods, algorithms, models and boundary con- ditions. On the other hand, control of accuracy has become a critical aspect in the development of predictive LES for design. The objective of this project is to create a framework of metrics aimed at quantifying the quality and accuracy of state-of-the-art LES in a manner that addresses the myriad of competing interdependencies. In a typical simulation cycle, only 20% of the computational time is actually usable. The rest is spent in case preparation, assessment, and validation, because of the lack of guidelines. This work increases confidence in the accuracy of a given solution while min- imizing the time obtaining the solution. The approach facilitates control of the tradeoffs between cost, accuracy, and uncertainties as a function of fidelity and methods employed. The analysis is coupled with advanced Uncertainty Quantification techniques employed to estimate confidence in model predictions and calibrate model's parameters. This work has provided positive conse- quences on the accuracy of the results delivered by LES and will soon have a broad impact on research supported both by the DOE and elsewhere.

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

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

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

    2013-07-12

    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 3 × 3 and 5 × 5 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 carriedmore » 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 singlephase incompressible Navier-Stokes equations. The simulations explicitly resolve the large scale motions of the turbulent flow field using first principles and rely on a monotonicity-preserving numerical technique to represent the unresolved scales. Each series of simulations for the 3 × 3 and 5 × 5 rod-bundle geometries is an analysis of the flow field statistics combined with a mesh-refinement study and validation with available experimental data. Our primary focus is the time history and statistics of the forces loading the fuel rods. These hydrodynamic forces are believed to be the key player resulting in rod vibration and GTRF wear, one of the leading causes for leaking nuclear fuel which costs power utilities millions of dollars in preventive measures. As a result, we demonstrate that implicit large-eddy simulation of rod-bundle flows is a viable way to calculate the excitation forces for the GTRF problem.« less

  7. Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research

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

    Control Concept | Department of Energy Understanding the detailed chemistry of Nox Reduction across the combined LNT+SCR system. deer10_crocker.pdf (827.9 KB) More Documents & Publications Development of Optimal Catalyst Designs and Operating Strategies for Lean NOx Reduction in Coupled LNT-SCR Systems Lean NOx Reduction with Dual Layer LNT/SCR Catalysts Diesel NOx Emission Control Concept | Department of Energy

    Experimental results show low-emissions potential - possibly T2/B2

  8. Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research

    Broader source: Energy.gov [DOE]

    2013 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

  9. Diagnosis of Differences Between Stratiform Clouds Simulated by Large-Eddy Simulation and Single-Column Models

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

    Diagnosis of Differences Between Stratiform Clouds and Simulated by Large-Eddy Simulation and Single-Column Models S. J. Ghan and M. Ovtchinnikov Climate Physics Pacific Northwest National Laboratory Richland, Washington Introduction An adequate parameterization of cloud microphysics is essential for estimating the indirect aerosol effect in large-scale models. Such a parameterization must rely on a physically sound treatment of spatial variability that affects many microphysical processes in a

  10. Calibration and Forward Uncertainty Propagation for Large-eddy Simulations of Engineering Flows

    SciTech Connect (OSTI)

    Templeton, Jeremy Alan; Blaylock, Myra L.; Domino, Stefan P.; Hewson, John C.; Kumar, Pritvi Raj; Ling, Julia; Najm, Habib N.; Ruiz, Anthony; Safta, Cosmin; Sargsyan, Khachik; Stewart, Alessia; Wagner, Gregory

    2015-09-01

    The objective of this work is to investigate the efficacy of using calibration strategies from Uncertainty Quantification (UQ) to determine model coefficients for LES. As the target methods are for engineering LES, uncertainty from numerical aspects of the model must also be quantified. 15 The ultimate goal of this research thread is to generate a cost versus accuracy curve for LES such that the cost could be minimized given an accuracy prescribed by an engineering need. Realization of this goal would enable LES to serve as a predictive simulation tool within the engineering design process.

  11. Mean-state acceleration of cloud-resolving models and large eddy simulations

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

    Jones, C. R.; Bretherton, C. S.; Pritchard, M. S.

    2015-10-29

    In this study, large eddy simulations and cloud-resolving models (CRMs) are routinely used to simulate boundary layer and deep convective cloud processes, aid in the development of moist physical parameterization for global models, study cloud-climate feedbacks and cloud-aerosol interaction, and as the heart of superparameterized climate models. These models are computationally demanding, placing practical constraints on their use in these applications, especially for long, climate-relevant simulations. In many situations, the horizontal-mean atmospheric structure evolves slowly compared to the turnover time of the most energetic turbulent eddies. We develop a simple scheme to reduce this time scale separation to accelerate themore » evolution of the mean state. Using this approach we are able to accelerate the model evolution by a factor of 2–16 or more in idealized stratocumulus, shallow and deep cumulus convection without substantial loss of accuracy in simulating mean cloud statistics and their sensitivity to climate change perturbations. As a culminating test, we apply this technique to accelerate the embedded CRMs in the Superparameterized Community Atmosphere Model by a factor of 2, thereby showing that the method is robust and stable to realistic perturbations across spatial and temporal scales typical in a GCM.« less

  12. Analysis of noise radiation mechanisms in hot subsonic jet from a validated large eddy simulation solution

    SciTech Connect (OSTI)

    Lorteau, Mathieu Cléro, Franck Vuillot, François

    2015-07-15

    In the framework of jet noise computation, a numerical simulation of a subsonic turbulent hot jet is performed using large-eddy simulation. A geometrical tripping is used in order to trigger the turbulence at the nozzle exit. In a first part, the validity of the simulation is assessed by comparison with experimental measurements. The mean and rms velocity fields show good agreement, so do the azimuthal composition of the near pressure field and the far field spectra. Discrepancies remain close to the nozzle exit which lead to a limited overestimation of the pressure levels in both near and far fields, especially near the 90{sup ∘} angular sector. Two point correlation analyses are then applied to the data obtained from the simulation. These enable to link the downstream acoustic radiation, which is the main direction of radiation, to pressure waves developing in the shear layer and propagating toward the potential core end. The intermittency of the downstream acoustic radiation is evidenced and related to the coherent structures developing in the shear layer.

  13. Mean-state acceleration of cloud-resolving models and large eddy simulations

    SciTech Connect (OSTI)

    Jones, C. R.; Bretherton, C. S.; Pritchard, M. S.

    2015-10-29

    In this study, large eddy simulations and cloud-resolving models (CRMs) are routinely used to simulate boundary layer and deep convective cloud processes, aid in the development of moist physical parameterization for global models, study cloud-climate feedbacks and cloud-aerosol interaction, and as the heart of superparameterized climate models. These models are computationally demanding, placing practical constraints on their use in these applications, especially for long, climate-relevant simulations. In many situations, the horizontal-mean atmospheric structure evolves slowly compared to the turnover time of the most energetic turbulent eddies. We develop a simple scheme to reduce this time scale separation to accelerate the evolution of the mean state. Using this approach we are able to accelerate the model evolution by a factor of 2–16 or more in idealized stratocumulus, shallow and deep cumulus convection without substantial loss of accuracy in simulating mean cloud statistics and their sensitivity to climate change perturbations. As a culminating test, we apply this technique to accelerate the embedded CRMs in the Superparameterized Community Atmosphere Model by a factor of 2, thereby showing that the method is robust and stable to realistic perturbations across spatial and temporal scales typical in a GCM.

  14. A hybrid stochastic-deconvolution model for large-eddy simulation of particle-laden flow

    SciTech Connect (OSTI)

    Michałek, W. R.; Kuerten, J. G. M.; Faculty EEMCS, University of Twente, 7500 AE Enschede ; Zeegers, J. C. H.; Liew, R.; Pozorski, J.; Geurts, B. J.; Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven

    2013-12-15

    We develop a hybrid model for large-eddy simulation of particle-laden turbulent flow, which is a combination of the approximate deconvolution model for the resolved scales and a stochastic model for the sub-grid scales. The stochastic model incorporates a priori results of direct numerical simulation of turbulent channel flow, which showed that the parameters in the stochastic model are quite independent of Reynolds and Stokes number. In order to correctly predict the flux of particles towards the walls an extra term should be included in the stochastic model, which corresponds to the term related to the well-mixed condition in Langevin models for particle dispersion in inhomogeneous turbulent flow. The model predictions are compared with results of direct numerical simulation of channel flow at a frictional Reynolds number of 950. The inclusion of the stochastic forcing is shown to yield a significant improvement over the approximate deconvolution model for the particles alone when combined with a Stokes dependent weight-factor for the well-mixed term.

  15. Large-eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics

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

    Maurer, K. D.; Bohrer, G.; Kenny, W. T.; Ivanov, V. Y.

    2015-04-30

    Surface roughness parameters, namely the roughness length and displacement height, are an integral input used to model surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and disregard the governing structural heterogeneity and dynamics. In this study, we use large-eddy simulations to explore, in silico, the effects of canopy-structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction.more » We found roughness parameters to be highly variable, but uncovered positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, as well as between eddy-penetration depth and maximum canopy height and leaf area index. We generalized our model results into a virtual "biometric" parameterization that relates roughness length and displacement height to canopy height, leaf area index, and gap fraction. Using a decade of wind and canopy-structure observations in a site in Michigan, we tested the effectiveness of our model-driven biometric parameterization approach in predicting the friction velocity over heterogeneous and disturbed canopies. We compared the accuracy of these predictions with the friction-velocity predictions obtained from the common simple approximation related to canopy height, the values calculated with large-eddy simulations of the explicit canopy structure as measured by airborne and ground-based lidar, two other parameterization approaches that utilize varying canopy-structure inputs, and the annual and decadal means of the surface roughness parameters at

  16. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    SciTech Connect (OSTI)

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations. The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.

  17. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

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

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; Vogelmann, Andrew M.; Toto, Tami; Ackerman, Andrew S.; McFarquhar, Greg M.; Jackson, Robert C.; Jonsson, Haflidi H.; Liu, Yangang

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations.more » The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.« less

  18. Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

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

    Christon, Mark A.; Lu, Roger; Bakosi, Jozsef; Nadiga, Balasubramanya T.; Karoutas, Zeses; Berndt, Markus

    2016-06-29

    Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuelmore » rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid–structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Furthermore, robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.« less

  19. Large eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics

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

    Maurer, K. D.; Bohrer, G.; Ivanov, V. Y.

    2014-11-27

    Surface roughness parameters are at the core of every model representation of the coupling and interactions between land-surface and atmosphere, and are used in every model of surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and do not vary them in response to spatial or temporal changes to canopy structure. In part, this is due to the difficulty of reducing the complexity of canopy structure and its spatiotemporal dynamic and heterogeneity to less than a handful of parameters describing its effects of atmosphere–surface interactions. In this study we use large-eddy simulationsmore » to explore, in silico, the effects of canopy structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction. We found roughness parameters to be highly variable, but were able to find positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, and between eddy-penetration depth and maximum canopy height and leaf area index. Using a decade of wind and canopy structure observations in a site in Michigan, we tested the effectiveness of our model-resolved parameters in predicting the frictional velocity over heterogeneous and disturbed canopies. We compared it with three other semi-empirical models and with a decade of meteorological observations. We found that parameterizations with fixed representations of roughness performed relatively well. Nonetheless, some empirical approaches that incorporate seasonal and inter-annual changes to the canopy structure performed even better than

  20. Large Eddy Simulation of a Wind Turbine Airfoil at High Freestream-Flow Angle

    SciTech Connect (OSTI)

    2015-04-13

    A simulation of the airflow over a section of a wind turbine blade, run on the supercomputer Mira at the Argonne Leadership Computing Facility. Simulations like these help identify ways to make turbine blades more efficient.

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

    SciTech Connect (OSTI)

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

    2012-07-01

    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.

  2. Validation/Uncertainty Quantification for Large Eddy Simulations of the heat flux in the Tangentially Fired Oxy-Coal Alstom Boiler Simulation Facility

    SciTech Connect (OSTI)

    Smith, P.J.; Eddings, E.G.; Ring, T.; Thornock, J.; Draper, T.; Isaac, B.; Rezeai, D.; Toth, P.; Wu, Y.; Kelly, K.

    2014-08-01

    The objective of this task is to produce predictive capability with quantified uncertainty bounds for the heat flux in commercial-scale, tangentially fired, oxy-coal boilers. Validation data came from the Alstom Boiler Simulation Facility (BSF) for tangentially fired, oxy-coal operation. This task brings together experimental data collected under Alstom’s DOE project for measuring oxy-firing performance parameters in the BSF with this University of Utah project for large eddy simulation (LES) and validation/uncertainty quantification (V/UQ). The Utah work includes V/UQ with measurements in the single-burner facility where advanced strategies for O2 injection can be more easily controlled and data more easily obtained. Highlights of the work include: • Simulations of Alstom’s 15 megawatt (MW) BSF, exploring the uncertainty in thermal boundary conditions. A V/UQ analysis showed consistency between experimental results and simulation results, identifying uncertainty bounds on the quantities of interest for this system (Subtask 9.1) • A simulation study of the University of Utah’s oxy-fuel combustor (OFC) focused on heat flux (Subtask 9.2). A V/UQ analysis was used to show consistency between experimental and simulation results. • Measurement of heat flux and temperature with new optical diagnostic techniques and comparison with conventional measurements (Subtask 9.3). Various optical diagnostics systems were created to provide experimental data to the simulation team. The final configuration utilized a mid-wave infrared (MWIR) camera to measure heat flux and temperature, which was synchronized with a high-speed, visible camera to utilize two-color pyrometry to measure temperature and soot concentration. • Collection of heat flux and temperature measurements in the University of Utah’s OFC for use is subtasks 9.2 and 9.3 (Subtask 9.4). Several replicates were carried to better assess the experimental error. Experiments were specifically designed for the

  3. Investigating wind turbine impacts on near-wake flow using profiling Lidar data and large-eddy simulations with an actuator disk model

    SciTech Connect (OSTI)

    Mirocha, Jeffrey D.; Rajewski, Daniel A.; Marjanovic, Nikola; Lundquist, Julie K.; Kosovic, Branko; Draxl, Caroline; Churchfield, Matthew J.

    2015-08-27

    In this study, wind turbine impacts on the atmospheric flow are investigated using data from the Crop Wind Energy Experiment (CWEX-11) and large-eddy simulations (LESs) utilizing a generalized actuator disk (GAD) wind turbine model. CWEX-11 employed velocity-azimuth display (VAD) data from two Doppler lidar systems to sample vertical profiles of flow parameters across the rotor depth both upstream and in the wake of an operating 1.5 MW wind turbine. Lidar and surface observations obtained during four days of July 2011 are analyzed to characterize the turbine impacts on wind speed and flow variability, and to examine the sensitivity of these changes to atmospheric stability. Significant velocity deficits (VD) are observed at the downstream location during both convective and stable portions of four diurnal cycles, with large, sustained deficits occurring during stable conditions. Variances of the streamwise velocity component, σu, likewise show large increases downstream during both stable and unstable conditions, with stable conditions supporting sustained small increases of σu , while convective conditions featured both larger magnitudes and increased variability, due to the large coherent structures in the background flow. Two representative case studies, one stable and one convective, are simulated using LES with a GAD model at 6 m resolution to evaluate the compatibility of the simulation framework with validation using vertically profiling lidar data in the near wake region. Virtual lidars were employed to sample the simulated flow field in a manner consistent with the VAD technique. Simulations reasonably reproduced aggregated wake VD characteristics, albeit with smaller magnitudes than observed, while σu values in the wake are more significantly underestimated. The results illuminate the limitations of using a GAD in combination with coarse model resolution in the simulation of near wake physics, and validation thereof using VAD data.

  4. Investigating wind turbine impacts on near-wake flow using profiling Lidar data and large-eddy simulations with an actuator disk model

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

    Mirocha, Jeffrey D.; Rajewski, Daniel A.; Marjanovic, Nikola; Lundquist, Julie K.; Kosovic, Branko; Draxl, Caroline; Churchfield, Matthew J.

    2015-08-27

    In this study, wind turbine impacts on the atmospheric flow are investigated using data from the Crop Wind Energy Experiment (CWEX-11) and large-eddy simulations (LESs) utilizing a generalized actuator disk (GAD) wind turbine model. CWEX-11 employed velocity-azimuth display (VAD) data from two Doppler lidar systems to sample vertical profiles of flow parameters across the rotor depth both upstream and in the wake of an operating 1.5 MW wind turbine. Lidar and surface observations obtained during four days of July 2011 are analyzed to characterize the turbine impacts on wind speed and flow variability, and to examine the sensitivity of thesemore » changes to atmospheric stability. Significant velocity deficits (VD) are observed at the downstream location during both convective and stable portions of four diurnal cycles, with large, sustained deficits occurring during stable conditions. Variances of the streamwise velocity component, σu, likewise show large increases downstream during both stable and unstable conditions, with stable conditions supporting sustained small increases of σu , while convective conditions featured both larger magnitudes and increased variability, due to the large coherent structures in the background flow. Two representative case studies, one stable and one convective, are simulated using LES with a GAD model at 6 m resolution to evaluate the compatibility of the simulation framework with validation using vertically profiling lidar data in the near wake region. Virtual lidars were employed to sample the simulated flow field in a manner consistent with the VAD technique. Simulations reasonably reproduced aggregated wake VD characteristics, albeit with smaller magnitudes than observed, while σu values in the wake are more significantly underestimated. The results illuminate the limitations of using a GAD in combination with coarse model resolution in the simulation of near wake physics, and validation thereof using VAD data.« less

  5. Coupling a Mesoscale Numerical Weather Prediction Model with Large-Eddy Simulation for Realistic Wind Plant Aerodynamics Simulations (Poster)

    SciTech Connect (OSTI)

    Draxl, C.; Churchfield, M.; Mirocha, J.; Lee, S.; Lundquist, J.; Michalakes, J.; Moriarty, P.; Purkayastha, A.; Sprague, M.; Vanderwende, B.

    2014-06-01

    Wind plant aerodynamics are influenced by a combination of microscale and mesoscale phenomena. Incorporating mesoscale atmospheric forcing (e.g., diurnal cycles and frontal passages) into wind plant simulations can lead to a more accurate representation of microscale flows, aerodynamics, and wind turbine/plant performance. Our goal is to couple a numerical weather prediction model that can represent mesoscale flow [specifically the Weather Research and Forecasting model] with a microscale LES model (OpenFOAM) that can predict microscale turbulence and wake losses.

  6. Intercomparison of Large-eddy Simulations of Arctic Mixed-phase Clouds: Importance of Ice Size Distribution Assumptions

    SciTech Connect (OSTI)

    Ovchinnikov, Mikhail; Ackerman, Andrew; Avramov, Alex; Cheng, Anning; Fan, Jiwen; Fridlind, Ann; Ghan, Steven J.; Harrington, Jerry Y.; Hoose, Corinna; Korolev, Alexei; McFarquhar, Greg; Morrison, H.; Paukert, Marco; Savre, Julien; Shipway, Ben; Shupe, Matthew D.; Solomon, Amy; Sulia, Kara

    2014-03-14

    Large-eddy simulations of mixed-phase Arctic clouds by 11 different models are analyzed with the goal of improving understanding and model representation of processes controlling the evolution of these clouds. In a case based on observations from the Indirect and Semi-Direct Aerosol Campaign (ISDAC), it is found that ice number concentration, Ni, exerts significant influence on the cloud structure. Increasing Ni leads to a substantial reduction in liquid water path (LWP) and potential cloud dissipation, in agreement with earlier studies. By comparing simulations with the same microphysics coupled to different dynamical cores as well as the same dynamics coupled to different microphysics schemes, it is found that the ice water path (IWP) is mainly controlled by ice microphysics, while the inter-model differences in LWP are largely driven by physics and numerics of the dynamical cores. In contrast to previous intercomparisons, all models here use the same ice particle properties (i.e., mass-size, mass-fall speed, and mass-capacitance relationships) and a common radiation parameterization. The constrained setup exposes the importance of ice particle size distributions (PSD) in influencing cloud evolution. A clear separation in LWP and IWP predicted by models with bin and bulk microphysical treatments is documented and attributed primarily to the assumed shape of ice PSD used in bulk schemes. Compared to the bin schemes that explicitly predict the PSD, schemes assuming exponential ice PSD underestimate ice growth by vapor deposition and overestimate mass-weighted fall speed leading to an underprediction of IWP by a factor of two in the considered case.

  7. Using Mesoscale Weather Model Output as Boundary Conditions for Atmospheric Large-Eddy Simulations and Wind-Plant Aerodynamic Simulations (Presentation)

    SciTech Connect (OSTI)

    Churchfield, M. J.; Michalakes, J.; Vanderwende, B.; Lee, S.; Sprague, M. A.; Lundquist, J. K.; Moriarty, P. J.

    2013-10-01

    Wind plant aerodynamics are directly affected by the microscale weather, which is directly influenced by the mesoscale weather. Microscale weather refers to processes that occur within the atmospheric boundary layer with the largest scales being a few hundred meters to a few kilometers depending on the atmospheric stability of the boundary layer. Mesoscale weather refers to large weather patterns, such as weather fronts, with the largest scales being hundreds of kilometers wide. Sometimes microscale simulations that capture mesoscale-driven variations (changes in wind speed and direction over time or across the spatial extent of a wind plant) are important in wind plant analysis. In this paper, we present our preliminary work in coupling a mesoscale weather model with a microscale atmospheric large-eddy simulation model. The coupling is one-way beginning with the weather model and ending with a computational fluid dynamics solver using the weather model in coarse large-eddy simulation mode as an intermediary. We simulate one hour of daytime moderately convective microscale development driven by the mesoscale data, which are applied as initial and boundary conditions to the microscale domain, at a site in Iowa. We analyze the time and distance necessary for the smallest resolvable microscales to develop.

  8. ARM - LES ARM Symbiotic Simulation and Observation Workflow

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

    ThemesLES ARM Symbiotic Simulation and Observation Workflow LASSO Information LASSO Home LASSO Backgrounder Pilot Phase Begins for Routine Large-Eddy Simulations Pilot Project Timeline Presentations News Science LASSO Implementation Strategy LASSO Pilot Project Releases Related Information ARM Decadal Vision Archive of LASSO Information e-mail list Contacts William Gustafson, Lead Principal Investigator Andrew Vogelmann, Co-Principal Investigator Hanna Goss, Media Contact LES ARM Symbiotic

  9. Comparison of the Dynamic Wake Meandering Model, Large-Eddy Simulation, and Field Data at the Egmond aan Zee Offshore Wind Plant: Preprint

    SciTech Connect (OSTI)

    Churchfield, M. J.; Moriarty, P. J.; Hao, Y.; Lackner, M. A.; Barthelmie, R.; Lundquist, J.; Oxley, G. S.

    2014-12-01

    The focus of this work is the comparison of the dynamic wake meandering model and large-eddy simulation with field data from the Egmond aan Zee offshore wind plant composed of 36 3-MW turbines. The field data includes meteorological mast measurements, SCADA information from all turbines, and strain-gauge data from two turbines. The dynamic wake meandering model and large-eddy simulation are means of computing unsteady wind plant aerodynamics, including the important unsteady meandering of wakes as they convect downstream and interact with other turbines and wakes. Both of these models are coupled to a turbine model such that power and mechanical loads of each turbine in the wind plant are computed. We are interested in how accurately different types of waking (e.g., direct versus partial waking), can be modeled, and how background turbulence level affects these loads. We show that both the dynamic wake meandering model and large-eddy simulation appear to underpredict power and overpredict fatigue loads because of wake effects, but it is unclear that they are really in error. This discrepancy may be caused by wind-direction uncertainty in the field data, which tends to make wake effects appear less pronounced.

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

    SciTech Connect (OSTI)

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

    2010-03-03

    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.

  11. Vehicle Technologies Office Merit Review 2016: Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research

    Office of Energy Efficiency and Renewable Energy (EERE)

    Presentation given by Sandia National Laboratory (SNL) at the 2016 DOE Vehicle Technologies Office and Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting about...

  12. Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine Combustion Research

    Broader source: Energy.gov [DOE]

    2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C.

  13. Large Eddy Simulation Modeling of Flashback and Flame Stabilization in Hydrogen-Rich Gas Turbines Using a Hierarchical Validation Approach

    SciTech Connect (OSTI)

    Clemens, Noel

    2015-09-30

    This project was a combined computational and experimental effort to improve predictive capability for boundary layer flashback of premixed swirl flames relevant to gas-turbine power plants operating with high-hydrogen-content fuels. During the course of this project, significant progress in modeling was made on four major fronts: 1) use of direct numerical simulation of turbulent flames to understand the coupling between the flame and the turbulent boundary layer; 2) improved modeling capability for flame propagation in stratified pre-mixtures; 3) improved portability of computer codes using the OpenFOAM platform to facilitate transfer to industry and other researchers; and 4) application of LES to flashback in swirl combustors, and a detailed assessment of its capabilities and limitations for predictive purposes. A major component of the project was an experimental program that focused on developing a rich experimental database of boundary layer flashback in swirl flames. Both methane and high-hydrogen fuels, including effects of elevated pressure (1 to 5 atm), were explored. For this project, a new model swirl combustor was developed. Kilohertz-rate stereoscopic PIV and chemiluminescence imaging were used to investigate the flame propagation dynamics. In addition to the planar measurements, a technique capable of detecting the instantaneous, time-resolved 3D flame front topography was developed and applied successfully to investigate the flow-flame interaction. The UT measurements and legacy data were used in a hierarchical validation approach where flows with increasingly complex physics were used for validation. First component models were validated with DNS and literature data in simplified configurations, and this was followed by validation with the UT 1-atm flashback cases, and then the UT high-pressure flashback cases. The new models and portable code represent a major improvement over what was available before this project was initiated.

  14. LES Modeling for IC Engines | Department of Energy

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

    LES Modeling for IC Engines LES Modeling for IC Engines Large eddy simulation offers better accuracy and sensitivity to study cyclic variability, mode transition and mixing effects in engine design and operation deer12_rutland.pdf (1.36 MB) More Documents & Publications Large Eddy Simulation (LES) Applied to Advanced Engine Combustion Research Vehicle Technologies Office Merit Review 2016: Advancements in Fuel Spray and Combustion Modeling with High Performance Computing Resources

  15. LES ARM Symbiotic Simulation and Observation (LASSO) Implementation Strategy

    SciTech Connect (OSTI)

    Gustafson Jr., WI; Vogelmann, AM

    2015-09-01

    This document illustrates the design of the Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) workflow to provide a routine, high-resolution modeling capability to augment the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s high-density observations. LASSO will create a powerful new capability for furthering ARM’s mission to advance understanding of cloud, radiation, aerosol, and land-surface processes. The combined observational and modeling elements will enable a new level of scientific inquiry by connecting processes and context to observations and providing needed statistics for details that cannot be measured. The result will be improved process understanding that facilitates concomitant improvements in climate model parameterizations. The initial LASSO implementation will be for ARM’s Southern Great Plains site in Oklahoma and will focus on shallow convection, which is poorly simulated by climate models due in part to clouds’ typically small spatial scale compared to model grid spacing, and because the convection involves complicated interactions of microphysical and boundary layer processes.

  16. A filtered tabulated chemistry model for LES of premixed combustion

    SciTech Connect (OSTI)

    Fiorina, B.; Auzillon, P.; Darabiha, N.; Gicquel, O.; Veynante, D.; Vicquelin, R.

    2010-03-15

    A new modeling strategy called F-TACLES (Filtered Tabulated Chemistry for Large Eddy Simulation) is developed to introduce tabulated chemistry methods in Large Eddy Simulation (LES) of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when subgrid scale turbulence vanishes as LES should tend toward Direct Numerical Simulation (DNS). The filtered flame structure is mapped using 1-D filtered laminar premixed flames. Closure of the filtered progress variable and the energy balance equations are carefully addressed in a fully compressible formulation. The methodology is first applied to 1-D filtered laminar flames, showing the ability of the model to recover the laminar flame speed and the correct chemical structure when the flame wrinkling is completely resolved. The model is then extended to turbulent combustion regimes by including subgrid scale wrinkling effects in the flame front propagation. Finally, preliminary tests of LES in a 3-D turbulent premixed flame are performed. (author)

  17. LES ARM Symbiotic Simulation and Observation (LASSO) Implementation...

    Office of Scientific and Technical Information (OSTI)

    This document illustrates the design of the Large-Eddy ... LASSO will create a powerful new capability for furthering ... The result will be improved process understanding that ...

  18. Simulating atmosphere flow for wind energy applications with WRF-LES

    SciTech Connect (OSTI)

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

    2008-01-14

    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

  19. Dynamic procedure for filtered gyrokinetic simulations

    SciTech Connect (OSTI)

    Morel, P.; Banon Navarro, A.; Albrecht-Marc, M.; Carati, D.; Merz, F.; Goerler, T.; Jenko, F.

    2012-01-15

    Large eddy simulations (LES) of gyrokinetic plasma turbulence are investigated as interesting candidates to decrease the computational cost. A dynamic procedure is implemented in the gene code, allowing for dynamic optimization of the free parameters of the LES models (setting the amplitudes of dissipative terms). Employing such LES methods, one recovers the free energy and heat flux spectra obtained from highly resolved direct numerical simulations. Systematic comparisons are performed for different values of the temperature gradient and magnetic shear, parameters which are of prime importance in ion temperature gradient driven turbulence. Moreover, the degree of anisotropy of the problem, which can vary with parameters, can be adapted dynamically by the method that shows gyrokinetic large eddy simulation to be a serious candidate to reduce numerical cost of gyrokinetic solvers.

  20. Adaptive LES Methodology for Turbulent Flow Simulations

    SciTech Connect (OSTI)

    Oleg V. Vasilyev

    2008-06-12

    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

  1. LES ARM Symbiotic Simulation and Observation (LASSO) Implementation Strategy

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

    9 LES ARM Symbiotic Simulation and Observation (LASSO) Implementation Strategy WI Gustafson Jr. AM Vogelmann September 2015 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States 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

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

    SciTech Connect (OSTI)

    Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E

    2012-01-01

    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.

  3. Combustion Energy Frontier Research Center Post-Doctoral Position in Advanced Combustion Simulations

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

    Energy Frontier Research Center (CEFRC) seeks outstanding applicants for the position of post-doctoral research associate to perform research at Cornell University and Sandia National Laboratories on advanced simulations of turbulent combustion. This position is as a Combustion Energy Research Fellow, as described at http://pcl.princeton.edu/efrc/fellow_Flyer.html . The project involves two simulation methodologies: direct numerical simulation (DNS); and large-eddy simulation (LES) using the

  4. Combustion Energy Frontier Research Center Post-Doctoral Position in Advanced Combustion Simulations

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

    EFRC seeks outstanding applicants for the position of post-doctoral research associate to perform research at Cornell University and Sandia National Laboratories on advanced simulations of turbulent combustion. The project involves two simulation methodologies: direct numerical simulation (DNS); and large-eddy simulation (LES) using the filtered density function (FDF) approach. DNS involves minimal modeling, but is restricted (by computational capabilities) to simple geometries and a moderate

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

    SciTech Connect (OSTI)

    Clifford Smith

    2003-09-01

    Application and testing of the new combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this 12th quarterly report. In this quarter, continued validation and testing of the combustion LES code was performed for the DOE-SimVal combustor. Also, beta testing by six consortium members was performed for various burner and combustor configurations. A list of suggested code improvements by the beta testers was itemized. Work will continue in FY04. A conditional modification to the contract will be granted. The additional work will focus on modeling/analyzing the SimVal experiments.

  6. Numerical simulation of the flow in wire-wrapped pin bundles: Effect of

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

    pin-wire contact modeling | Argonne Leadership Computing Facility simulation of the flow in wire-wrapped pin bundles: Effect of pin-wire contact modeling Authors: Merzari, E., Smith, J.G., Tentner, A., Pointer, W.D., Fischer, P. The rapid advancement of numerical techniques and the availability of increasingly powerful supercomputers recently enabled scientists to use large eddy simulation (LES) to simulate numerically the flow in a full subassembly composed of wire-wrapped pins. Because of

  7. Simulation of Post-Frontal Boundary Layers Observed During the ARM 2000 Cloud IOP

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

    Simulation of Post-Frontal Boundary Layers Observed During the ARM 2000 Cloud IOP D. B. Mechem and Y. L. Kogan Cooperative Institute for Mesoscale Meteorological Studies University of Oklahoma Norman, Oklahoma M. Poellot University of North Dakota Grand Forks, North Dakota Introduction Large-eddy simulation (LES) models have been widely employed in the study of radiatively forced cloud topped boundary layers (CTBL). These boundary layers are typically well mixed and characterized by a sharp jump

  8. Large-eddy simulation of the Rayleigh-Taylor instability on a massively parallel computer

    SciTech Connect (OSTI)

    Amala, P.A.K.

    1995-03-01

    A computational model for the solution of the three-dimensional Navier-Stokes equations is developed. This model includes a turbulence model: a modified Smagorinsky eddy-viscosity with a stochastic backscatter extension. The resultant equations are solved using finite difference techniques: the second-order explicit Lax-Wendroff schemes. This computational model is implemented on a massively parallel computer. Programming models on massively parallel computers are next studied. It is desired to determine the best programming model for the developed computational model. To this end, three different codes are tested on a current massively parallel computer: the CM-5 at Los Alamos. Each code uses a different programming model: one is a data parallel code; the other two are message passing codes. Timing studies are done to determine which method is the fastest. The data parallel approach turns out to be the fastest method on the CM-5 by at least an order of magnitude. The resultant code is then used to study a current problem of interest to the computational fluid dynamics community. This is the Rayleigh-Taylor instability. The Lax-Wendroff methods handle shocks and sharp interfaces poorly. To this end, the Rayleigh-Taylor linear analysis is modified to include a smoothed interface. The linear growth rate problem is then investigated. Finally, the problem of the randomly perturbed interface is examined. Stochastic backscatter breaks the symmetry of the stationary unstable interface and generates a mixing layer growing at the experimentally observed rate. 115 refs., 51 figs., 19 tabs.

  9. Large Eddy Simulation of Stable Boundary Layer Turbulent Processes in Complex Terrain

    SciTech Connect (OSTI)

    Eric D. Skyllingstad

    2005-01-26

    Research was performed using a turbulence boundary layer model to study the behavior of cold, dense flows in regions of complex terrain. Results show that flows develop a balance between turbulent entrainment of warm ambient air and dense, cold air created by surface cooling. Flow depth and strength is a function of downslope distance, slope angle and angle changes, and the ambient air temperature.

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

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

    Department of Energy 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

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

    SciTech Connect (OSTI)

    Steve Cannon; Baifang Zuo; Virgil Adumitroaie; Keith McDaniel; Cliff Smith

    2002-01-01

    Further development of a combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this fifth 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 further tested in the LES code. The use of multiple trees and periodic tree dumping was investigated. Implementation of the Linear Eddy Model (LEM) for subgrid chemistry was finished for serial applications. Validation of the model on a backstep reacting case was performed. Initial calculations of the SimVal experiment were performed for various barrel lengths, equivalence ratio, combustor shapes, and turbulence models. The effects of these variables on combustion instability was studied. 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. Next quarter, the 2nd consortium meeting will be held at CFDRC. LES software development and testing will continue. Alpha testing of the code will 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 chemical kinetics speed-up in CFD-ACE+, should be accomplished.

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

    SciTech Connect (OSTI)

    Not Available

    2012-04-01

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

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

    SciTech Connect (OSTI)

    Steven Cannon; Clifford Smith

    2003-04-01

    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.

  14. A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model

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

    Kemenov, Konstantin A.; Calhoon, William H.

    2015-03-24

    Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable,more » the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.« less

  15. A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model

    SciTech Connect (OSTI)

    Kemenov, Konstantin A.; Calhoon, William H.

    2015-03-24

    Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable, the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.

  16. Final Report on the “New Directions in the Variational Multiscale Formulation of Large Eddy Simulation of Turbulence”

    SciTech Connect (OSTI)

    Oberai, Assad A

    2013-07-16

    In the report we present a summary of the new models and algorithms developed by the PI and the students supported by this grant. These developments are described in detail in ten peer-reviewed journal articles that acknowledge support from this grant.

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

    SciTech Connect (OSTI)

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

    2002-04-30

    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.

  18. CgWind: A high-order accurate simulation tool for wind turbines and wind farms

    SciTech Connect (OSTI)

    Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

    2010-02-22

    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.

  19. Sandia Energy - Modeling

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

    systems. The engine combustion modeling is focused on developing Large Eddy Simulation (LES). LES is being used with closely coupled key target experiments to reveal new...

  20. Sandia Energy - Computational Fluid Dynamics Simulations Provide...

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

    from a VWiS large-eddy simulation. One of the primary roles of Sandia's Scaled Wind Farm Technology (SWiFT) facility will be to conduct detailed experiments on turbine wakes and...

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

    SciTech Connect (OSTI)

    Steve Cannon; Virgil Adumitroaie; Keith McDaniel; Cliff Smith

    2001-05-01

    Further development of a Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this second quarterly report. CFD Research Corporation (CFDRC) is developing the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. CFDRC has implemented and tested Smagorinsky and localized dynamic subgrid turbulence models on a 2.1 million cell DOE-NETL combustor case and a 400,000 cell nonreacting backstep case. Both cases showed good agreement between predicted and experimental results. The large DOE-NETL case results provided better agreement with the measured oscillation frequency than previous attempts because massive parallel computing (on a cluster of 24 pcs) allowed the entire computational domain, including the swirler vanes and fuel spokes, to be modeled. Subgrid chemistry models, including the conditional moment closure (CMC) and linear eddy model (LEM), are being tested and implemented. Reduced chemical mechanisms have been developed for emissions, ignition delay, extinction, and flame propagation using a computer automated reduction method (CARM). A 19-species natural gas mechanism, based on GRI2.11 and Miller-NO{sub x}, was shown to predict rich NO{sub x} emissions better than any previously published mechanisms. The ability to handle this mechanism in CFD-ACE+ was demonstrated by implementing operator splitting and a stiff ODE solver (DVODE). Efficient tabulation methods, including in situ adaptation and artificial neural nets, are being studied and will be implemented in the LES code. The LES combustion code development and testing is on schedule. Next quarter, initial results (including the DOE-NETL unstable combustor) with the CMC and LEM subgrid chemistry models will be completed and summarized.

  2. ARM - Publications: Science Team Meeting Documents: Variance...

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

    in shallow cumulus topped mixed layers is studied using large-eddy simulation (LES) results. The simulations are based on a range of different shallow cumulus cases,...

  3. ARM - Publications: Science Team Meeting Documents

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

    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...

  4. Doug Longman | Argonne National Laboratory

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

    of Nozzle Orifice Geometry Fuel Spray Modeling High-Fidelity Large Eddy Simulations (LES) Multi-Dimensional Modeling Simulation Approaches for Drop-in Biofuels Virtual Engine...

  5. Sticky Thermals: Evidence for a Dominant Balance Between

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

    by studying thousands of cloud thermals in a high- resolution large-eddy simulation (LES) of deep convection. Schematically, the acceleration of a cloud thermal can be written...

  6. Modeling Precipitating Cumulus Congestus Observed by the ARM...

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

    (GCMs). Typically, results from cloud-resolving models (CRMs) or large-eddy simulation (LES) models serve as benchmarks for developing and tuning single-column models (SCMs),...

  7. ARM - Publications: Science Team Meeting Documents

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

    University (b) Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting LES (large eddy simulation) models can explicitly resolve large turbulent eddies, which...

  8. Research Highlight

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

    convection using a new technique for large-eddy simulations (LES) called "Eulerian direct measurement". These results were confirmed by Dawe and Austin (2011) using a related...

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

    SciTech Connect (OSTI)

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

    2005-01-01

    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

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

    SciTech Connect (OSTI)

    Not Available

    2011-02-01

    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.

  11. Offshore Wind Farm Model Development – Upcoming Release of the University of Minnesota’s Virtual Wind Simulator

    Broader source: Energy.gov [DOE]

    Large-eddy simulation of wind farms with parameterization of wind turbines is emerging as a powerful tool for improving the performance and lowering the maintenance cost of existing wind farms and...

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

    SciTech Connect (OSTI)

    Sanjiva Lele

    2012-10-01

    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

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

    SciTech Connect (OSTI)

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

    2001-11-06

    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

  14. Bluff Body Flow Simulation Using a Vortex Element Method

    SciTech Connect (OSTI)

    Anthony Leonard; Phillippe Chatelain; Michael Rebel

    2004-09-30

    Heavy ground vehicles, especially those involved in long-haul freight transportation, consume a significant part of our nation's energy supply. it is therefore of utmost importance to improve their efficiency, both to reduce emissions and to decrease reliance on imported oil. At highway speeds, more than half of the power consumed by a typical semi truck goes into overcoming aerodynamic drag, a fraction which increases with speed and crosswind. Thanks to better tools and increased awareness, recent years have seen substantial aerodynamic improvements by the truck industry, such as tractor/trailer height matching, radiator area reduction, and swept fairings. However, there remains substantial room for improvement as understanding of turbulent fluid dynamics grows. The group's research effort focused on vortex particle methods, a novel approach for computational fluid dynamics (CFD). Where common CFD methods solve or model the Navier-Stokes equations on a grid which stretches from the truck surface outward, vortex particle methods solve the vorticity equation on a Lagrangian basis of smooth particles and do not require a grid. They worked to advance the state of the art in vortex particle methods, improving their ability to handle the complicated, high Reynolds number flow around heavy vehicles. Specific challenges that they have addressed include finding strategies to accurate capture vorticity generation and resultant forces at the truck wall, handling the aerodynamics of spinning bodies such as tires, application of the method to the GTS model, computation time reduction through improved integration methods, a closest point transform for particle method in complex geometrics, and work on large eddy simulation (LES) turbulence modeling.

  15. Microsoft PowerPoint - wrf_les_2007_zhu.ppt [Compatibility Mode]

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

    LES Testbed Prototype: ARM LES Testbed Prototype: Multi-Scale WRF Simulations of Boundary Layer Clouds Ping Zhu Florida International University Pavlos Kollias Brookhaven National Laboratory Bruce Albrecht University of Miami What is ARM-LES-Testbed ? It is structured to provide a framework for effectively organizing and using the extensive data generated by the ARM radars and other ARM observing systems for boundary layer cloud studies and for evaluating high resolution simulations. GCM/ PAR

  16. LASSO: Tying ARM Data and LES Modeling Together to Improve Climate Science

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

    LASSO: Tying ARM Data and LES Modeling Together to Improve Climate Science New Routine Modeling The pilot modeling project, called LASSO-the LES ARM Symbiotic Simulation and Observation workflow-is laying the groundwork to produce routine LES modeling at the ARM Southern Great Plains (SGP) megasite starting in 2017. The initial LASSO implementation will target shallow clouds and will later expand to other phenomena and ARM sites. A key to creating the next-generation Atmospheric Radiation

  17. Landfill Energy Systems LES | Open Energy Information

    Open Energy Info (EERE)

    Energy Systems LES Jump to: navigation, search Name: Landfill Energy Systems (LES) Place: Michigan Zip: 48393 Product: Landfill gas to energy systems project developer, gas...

  18. LES Modeling of High Resolution Satellite Cloud Spatial and Thermal

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

    Structure at ARM-SGP site: How well can we Simulate Clouds from Space? LES Modeling of High Resolution Satellite Cloud Spatial and Thermal Structure at ARM-SGP site: How well can we Simulate Clouds from Space? Dubey, Manvendra DOE/Los Alamos National Laboratory Chylek, Petr DOE/Los Alamos National Laboratory Reisner, Jon Los Alamos National Laboratory Porch, William Los Alamos National Laboratory Category: Cloud Properties We report high fidelity observations of the spatial and thermal

  19. CX-010779: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    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

  20. 2011_INCITE_Fact_Sheets.pdf | Department of Energy

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

    1_INCITE_Fact_Sheets.pdf 2011_INCITE_Fact_Sheets.pdf (745.56 KB) More Documents & Publications Advance Patent Waiver W(A)2006-028 Large Eddy Simulation (LES) Applied to LTC/Diesel/Hydrogen Engine Combustion Research Vehicle Technologies Office Merit Review 2016: Advancements in Fuel Spray and Combustion Modeling with High Performance Computing Resources

  1. Azimuthal Instabilities in Annular Combustion Chambers | Argonne Leadership

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

    Computing Facility Azimuthal Instabilities in Annular Combustion Chambers Authors: Wolf, P., Staffelbach, G., Balakrishnan, R., Roux, A., Poinsot, T. Large Eddy Simulations (LES) of a full annular helicopter gas turbine combustor have been performed. Emphasis is placed on the azimuthal mode that often appears in real configurations. The current LES are shown to capture these self-excited modes, with limited impact of the grid resolution. The structure of the azimuthal mode is discussed and

  2. On the simulation of shock-driven material mixing in high-Re flows (u)

    SciTech Connect (OSTI)

    Grinstein, Fernando F [Los Alamos National Laboratory

    2009-01-01

    Implicit large eddy simulation proposes to effectively rely on the use of subgrid modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive simulations of turbulent velocity fields are possible using a class of high resolution, non-oscillatory finite-volume (NFV) numerical algorithms. Truncation terms associated with NFV methods implicitly provide subgrid models capable of emulating the physical dynamics of the unresolved turbulent velocity fluctuations by themselves. The extension of the approach to the substantially more difficult problem of under-resolved material mixing by an under-resolved velocity field has not yet been investigated numerically, nor are there any theories as to when the methodology may be expected to be successful. Progress in addressing these issues in studies of shock-driven scalar mixing driven by Ritchmyer-Meshkov instabilities will be reported in the context of ongoing simulations of shock-tube laboratory experiments.

  3. ARM Dev Workshop Plenary Presentation Gustafson 201507.pptx

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

    Development of the LES ARM Symbiotic Simulation and Observation (LASSO) Workflow William I. Gustafson, Principal Investigator Pacific Northwest National Laboratory Andrew M. Vogelmann, Co-principal Investigator Brookhaven National Laboratory January 2014 Measurement Strategy Large-Eddy Simulation Scale (1 to 200 m) Cloud-Resolving Model Scale (1 to 4 km) Mesoscale Model Scale (4 to 20 km) Single-Column Model (100 km) General Circulation Model Scale (10 to 100 km, NCEP/ ECMWF Forcing) ARM

  4. LEM-CF Premixed Tool Kit

    Energy Science and Technology Software Center (OSTI)

    2015-01-19

    The purpose of LEM-CF Premixed Tool Kit is to process premixed flame simulation data from the LEM-CF solver (https://fileshare.craft-tech.com/clusters/view/lem-cf) into a large-eddy simulation (LES) subgrid model database. These databases may be used with a user-defined-function (UDF) that is included in the Tool Kit. The subgrid model UDF may be used with the ANSYS FLUENT flow solver or other commercial flow solvers.

  5. Sibendu Som | Argonne National Laboratory

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

    Sibendu Som Principal Mechanical Engineer News Engine design takes a major leap at Argonne The complex chemistry of combustion Argonne, Achates Power and Delphi Automotive to investigate new approach to engines E-mail ssom@anl.gov Website Google Scholar Projects Combustion Modeling with Detailed Chemistry Effect of Nozzle Orifice Geometry Fuel Spray Modeling High-Fidelity Large Eddy Simulations (LES) Multi-Dimensional Modeling Simulation Approaches for Drop-in Biofuels Virtual Engine Research

  6. A simple Analytical Model to Study and Control Azimuthal Instabilities in

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

    Annular Combustion Chambers | Argonne Leadership Computing Facility A simple Analytical Model to Study and Control Azimuthal Instabilities in Annular Combustion Chambers Authors: Parmentier, J-F., Salas, P., Wolf, P., Staffelbach, G., Nicoud, F., Poinsot, T. This study describes a simple analytical method to compute the azimuthal modes appearing in annular combustion chambers and help analyzing experimental, acoustic and large eddy simulation (LES) data obtained in these combustion chambers.

  7. 1

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

    Expression for Critical Radius and Generalization to Consider Spectral Dispersion Y Liu, P. H. Daum, and R. Mcraw Environmental Sciences Department Brookhaven National Laboratory Upton, New York Introduction Representation of cloud and precipitation processes is crucial for improving atmospheric models of various scales ranging from large eddy simulations (LES) to cloud resolving models (CRMs) to global climate models (GCMs) (Stokes and Schwartz 1994). A key process that must be parameterized is

  8. LES' URENCO-USA Facility | Department of Energy

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

    LES' URENCO-USA Facility LES' URENCO-USA Facility PowerPoint slides on LES's URENCO-USA Facility LES' URENCO-USA Facility (581.43 KB) More Documents & Publications 2014 Review of the Potential Impact of DOE Excess Uranium Inventory On the Commercial Markets Memorandum Memorializing Ex Parte Communication Report on the Effect the Low Enriched Uranium Delivered Under the Highly Enriched Uranium Agreement Between the USA and the Russian Federation has on the Domestic Uranium Mining, Conversion,

  9. The role of large eddy fluctuations in the Madison Dynamo Experiment

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

    ... Shpil'rain, E., Yakimovich, K. A., Fomin, V. A., Skovorodjko, S. N., and Mozgovoi, A. G., Dynamic and Kinematic Viscosity of Liquid Alkali Metals, International Union of Pure and ...

  10. Massively Parallel LES of Azimuthal Thermo-Acoustic Instabilities...

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

    Massively Parallel LES of Azimuthal Thermo-Acoustic Instabilities in Annular Gas Turbines Authors: Wolf, P., Staffelbach, G., Roux, A., Gicquel, L., Poinsot, T., Moureau, V. ...

  11. Using LES to Study Reacting Flows and Instabilities in Annular...

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

    Using LES to Study Reacting Flows and Instabilities in Annular Combustion Chambers Authors: Staffelbach, G., Wolf, P., Roux, A., Poinsot, T., Balakrishnan, R. Great prominence is ...

  12. Direct numerical simulation of turbulent reacting flows

    SciTech Connect (OSTI)

    Chen, J.H.

    1993-12-01

    The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.

  13. ARM - Evaluation Product - LASSO Alpha 1 Data Bundles

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

    ProductsLASSO Alpha 1 Data Bundles ARM Data Discovery Browse Data Documentation Use the Data File Inventory tool to view data availability at the file level. Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Evaluation Product : LASSO Alpha 1 Data Bundles [ ARM research - evaluation data product ] The Alpha 1 release contains initial data bundles from the large-eddy simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) workflow pilot

  14. Learning environment simulator: a tool for local decision makers and first responders

    SciTech Connect (OSTI)

    Leclaire, Rene J; Hirsch, Gary B

    2009-01-01

    The National Infrastructure Simulation and Analysis Center (NISAC) has developed a prototype learning environment simulator (LES) based on the Critical Infrastructure Protection Decision Support System (CIPDSS) infrastructure and scenario models. The LES is designed to engage decision makers at the grass-roots level (local/city/state) to deepen their understanding of an evolving crisis, enhance their intuition and allow them to test their own strategies for events before they occur. An initial version is being developed, centered on a pandemic influenza outbreak and has been successfully tested with a group of hospital administrators and first responders. LES is not a predictive tool but rather a simulated environment allowing the user to experience the complexities of a crisis before it happens. Users can contrast various approaches to the crisis, competing with alternative strategies of their own or other participants. LES is designed to assist decision makers in making informed choices by functionally representing relevant scenarios before they occur, including impacts to critical infrastructures with their interdependencies, and estimating human health & safety and economic impacts. In this paper a brief overview of the underlying models are given followed by a description of the LES, its interface and usage and an overview of the experience testing LES with a group of hospital administrators and first responders. The paper concludes with a brief discussion of the work remaining to make LES operational.

  15. Numerical simulations of the two-dimensional multimode Richtmyer-Meshkov instability

    SciTech Connect (OSTI)

    Thornber, B.; Zhou, Y.

    2015-03-15

    The two-dimensional Richtmyer-Meshkov instability occurs as shock waves pass through a perturbed material interface, triggering transition to an inhomogeneous turbulence variable density flow. This paper presents a series of large-eddy-simulations of the two dimensional turbulent RM instability and compares the results to the fully three dimensional simulations. There are two aims for this paper, the first is to explore what numerical resolution is required for a statistically converged solution for a two dimensional inhomogeneous flow field. The second aim is to elucidate the key differences in flow physics between the two dimensional and three dimensional Richtmyer-Meshkov instabilities, particularly their asymptotic self-similar regime. Convergence is achieved using 64 independent realisations and grid resolutions up to 4096{sup 2} in the plane. It is shown that for narrowband cases the growth rate θ = 0.48 which is substantially higher than the three-dimensional equivalent. Mix measures are consistently lower compared to three-dimensional, and the kinetic energy distribution is homogeneous at late time. The broadband case has a similar initial growth rate as the three-dimensional case, with a marginally lower θ = 0.63. Mix is similar in magnitude, but is reducing at late time. The spectra in both cases exhibit the dual-cascade expected from two-dimensional turbulence.

  16. Offshore Wind Farm Model Development - Upcoming Release of the...

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

    Offshore Wind Farm Model Development - Upcoming Release of the University of Minnesota's ... September 16, 2015 - 1:14pm Addthis Large-eddy simulation of wind farms with ...

  17. Modifications to WRFs dynamical core to improve the treatment...

    Office of Scientific and Technical Information (OSTI)

    Modifications to WRFs dynamical core to improve the treatment of moisture for large-eddy simulations Title: Modifications to WRFs dynamical core to improve the treatment of ...

  18. ARM - Publications: Science Team Meeting Documents

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

    cloud scenes created by a large eddy simulation model. Progressively greater degrees of tilt and stretching were imposed on these scenes, so that an ensemble of scenes were...

  19. Search for: All records | DOE PAGES

    Office of Scientific and Technical Information (OSTI)

    fields in their large-eddy simulations (LESs) of marine stratocumulus using the Weather Research and Forecasting (WRF) model exhibit a strong sensitivity to time stepping choices. ...

  20. 1

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

    numerical models. QJRMS., 125, 391-423. Stevens, B., C. -H. Moeng, and P. P. Sullivan, 1999: Large-eddy simulations of radiatively driven convection: Sensitivities to the...

  1. RACORO continental boundary layer cloud investigations. 3. Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus

    SciTech Connect (OSTI)

    Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; Fridlind, Ann; Endo, Satoshi; Song, Hua; Feng, Sha; Toto, Tami; Li, Zhijin; Zhang, Minghua

    2015-06-19

    Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) project has constructed case studies from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.

  2. RACORO continental boundary layer cloud investigations. 3. Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus

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

    Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; Fridlind, Ann; Endo, Satoshi; Song, Hua; Feng, Sha; Toto, Tami; Li, Zhijin; Zhang, Minghua

    2015-06-19

    Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) project has constructed case studies from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only amore » relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.« less

  3. Microsoft Word - Advanced Solution Verification of CFD Solutions for LES of GTRF_Rider_August23.docx

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

    VUQ.VVDA.P4.03 Jim Stewart SNL Completed: 8/31/2012 CASL-U-2012-0132-000 Advanced Solution Verification of CFD Solutions for LES o f R elevance t o GTRF Estimates. William J. Rider and James R. Kamm Sandia N ational L aboratories Albuquerque, NM 87185 August 31, 2012 SAND 2 012---7199P Summary The purpose of this work is to d emonstrate advanced solution verification (i.e., numerical error estimation) techniques on computational fluid dynamics simulations of interest to CASL. The specific case

  4. Petascale algorithms for reactor hydrodynamics.

    SciTech Connect (OSTI)

    Fischer, P.; Lottes, J.; Pointer, W. D.; Siegel, A.

    2008-01-01

    We describe recent algorithmic developments that have enabled large eddy simulations of reactor flows on up to P = 65, 000 processors on the IBM BG/P at the Argonne Leadership Computing Facility. Petascale computing is expected to play a pivotal role in the design and analysis of next-generation nuclear reactors. Argonne's SHARP project is focused on advanced reactor simulation, with a current emphasis on modeling coupled neutronics and thermal-hydraulics (TH). The TH modeling comprises a hierarchy of computational fluid dynamics approaches ranging from detailed turbulence computations, using DNS (direct numerical simulation) and LES (large eddy simulation), to full core analysis based on RANS (Reynolds-averaged Navier-Stokes) and subchannel models. Our initial study is focused on LES of sodium-cooled fast reactor cores. The aim is to leverage petascale platforms at DOE's Leadership Computing Facilities (LCFs) to provide detailed information about heat transfer within the core and to provide baseline data for less expensive RANS and subchannel models.

  5. Massively Parallel LES of Azimuthal Thermo-Acoustic Instabilities in

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

    Annular Gas Turbines | Argonne Leadership Computing Facility Massively Parallel LES of Azimuthal Thermo-Acoustic Instabilities in Annular Gas Turbines Authors: Wolf, P., Staffelbach, G., Roux, A., Gicquel, L., Poinsot, T., Moureau, V. Increasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines, which are unfortunately more and more prone to combustion instabilities. In the particular field of annular

  6. Simulators IV

    SciTech Connect (OSTI)

    Fairchild, B.T.

    1987-01-01

    These proceedings contain papers on simulators with artificial intelligence, and the human decision making process; visuals for simulators: human factors, training, and psycho-physical impacts; the role of institutional structure on simulation projects; maintenance trainers for economic value and safety; biomedical simulators for understanding nature, for medical benefits, and the physiological effects of simulators; the mathematical models and numerical techniques that drive today's simulators; and the demography of simulators, with census papers identifying the population of real-time simulator training devices; nuclear reactors.

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

    Broader source: Energy.gov [DOE]

    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.

  8. Minimalist Model of Ice Microphysics in Mixed-phase Stratiform Clouds

    SciTech Connect (OSTI)

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

    2013-07-28

    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.

  9. A new class of finite element variational multiscale turbulence models for incompressible magnetohydrodynamics

    SciTech Connect (OSTI)

    Sondak, D.; Shadid, J. N.; Oberai, A. A.; Pawlowski, R. P.; Cyr, E. C.; Smith, T. M.

    2015-04-29

    New large eddy simulation (LES) turbulence models for incompressible magnetohydrodynamics (MHD) derived from the variational multiscale (VMS) formulation for finite element simulations are introduced. The new models include the variational multiscale formulation, a residual-based eddy viscosity model, and a mixed model that combines both of these component models. Each model contains terms that are proportional to the residual of the incompressible MHD equations and is therefore numerically consistent. Moreover, each model is also dynamic, in that its effect vanishes when this residual is small. The new models are tested on the decaying MHD Taylor Green vortex at low and high Reynolds numbers. The evaluation of the models is based on comparisons with available data from direct numerical simulations (DNS) of the time evolution of energies as well as energy spectra at various discrete times. Thus a numerical study, on a sequence of meshes, is presented that demonstrates that the large eddy simulation approaches the DNS solution for these quantities with spatial mesh refinement.

  10. A new class of finite element variational multiscale turbulence models for incompressible magnetohydrodynamics

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

    Sondak, D.; Shadid, J. N.; Oberai, A. A.; Pawlowski, R. P.; Cyr, E. C.; Smith, T. M.

    2015-04-29

    New large eddy simulation (LES) turbulence models for incompressible magnetohydrodynamics (MHD) derived from the variational multiscale (VMS) formulation for finite element simulations are introduced. The new models include the variational multiscale formulation, a residual-based eddy viscosity model, and a mixed model that combines both of these component models. Each model contains terms that are proportional to the residual of the incompressible MHD equations and is therefore numerically consistent. Moreover, each model is also dynamic, in that its effect vanishes when this residual is small. The new models are tested on the decaying MHD Taylor Green vortex at low and highmore » Reynolds numbers. The evaluation of the models is based on comparisons with available data from direct numerical simulations (DNS) of the time evolution of energies as well as energy spectra at various discrete times. Thus a numerical study, on a sequence of meshes, is presented that demonstrates that the large eddy simulation approaches the DNS solution for these quantities with spatial mesh refinement.« less

  11. Virtual Flow Simulator

    Energy Science and Technology Software Center (OSTI)

    2015-10-05

    Virtual Flow Simulator (VFS) is a state-of-the-art computational fluid mechanics (CFD) package that is capable of simulating multi-physics/multi-phase flows with the most advanced turbulence models (RANS, LES) over complex terrains. The flow solver is based on the Curvilinear Immersed Boundary (CURVIB) method to handle geometrically complex and moving domains. Different modules of the VFS package can provide different simulation capabilities for specific applications ranging from the fluid-structure interaction (FSI) of solid and deformable bodies, themore » two-phase free surface flow solver based on the level set method for ocean waves, sediment transport models in rivers and the large-scale models of wind farms based on actuator lines and surfaces. All numerical features of VFS package have been validated with known analytical and experimental data as reported in the related journal articles. VFS package is suitable for a broad range of engineering applications within different industries. VFS has been used in different projects with applications in wind and hydrokinetic energy, offshore and near-shore ocean studies, cardiovascular and biological flows, and natural streams and river morphodynamics. Over the last decade, the development of VFS has been supported and assisted with the help of various United States companies and federal agencies that are listed in the sponsor lists. In this version, VFS-Wind contains all the necessary modeling tools for wind energy applications, including land-based and offshore wind farms. VFS is highly scalable to run on either desktop computers or high performance clusters (up to 16,000 CPUs). This released version comes with a detailed user’s manual and a set of case studies designed to facilitate the learning of the various aspects of the code in a comprehensive manner. The included documentation and support material has been elaborated in a collaboration effort with Sandia National Labs under the contract DE-EE0005482

  12. ITM Benchmark #1: PHASTA Results Igor Bolotnov North Carolina...

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

    ... Only densityviscosity values were used for the simulation (right column of Table 4). ... K. E., 2005. A parametric-free dynamic subgrid-scale model for large-eddy simulation. ...

  13. Wind Simulation

    Energy Science and Technology Software Center (OSTI)

    2008-12-31

    The Software consists of a spreadsheet written in Microsoft Excel that provides an hourly simulation of a wind energy system, which includes a calculation of wind turbine output as a power-curve fit of wind speed.

  14. Multi-scale thermalhydraulic analyses performed in Nuresim and Nurisp projects

    SciTech Connect (OSTI)

    Bestion, D.; Lucas, D.; Anglart, H.; Niceno, B.; Vyskocil, L.

    2012-07-01

    The NURESIM and NURISP successive projects of the 6. and 7. European Framework Programs joined the efforts of 21 partners for developing and validating a reference multi-physics and multi-scale platform for reactor simulation. The platform includes system codes, component codes, and also CFD or CMFD simulation tools. Fine scale CFD simulations are useful for a better understanding of physical processes, for the prediction of small scale geometrical effects and for solving problems that require a fine space and/or time resolution. Many important safety issues usually treated at the system scale may now benefit from investigations at a CFD scale. The Pressurized Thermal Shock is investigated using several simulation scales including Direct Numerical Simulation, Large Eddy Simulation, Very Large Eddy Simulation and RANS approaches. At the end a coupling of system code and CFD is applied. Condensation Induced Water-Hammer was also investigated at both CFD and 1-D scale. Boiling flow in a reactor core up to Departure from Nucleate Boiling or Dry-Out is investigated at scales much smaller than the classical subchannel analysis codes. DNS was used to investigate very local processes whereas CFD in both RANS and LES was used to simulate bubbly flow and Euler-Lagrange simulations were used for annular mist flow investigations. Loss of Coolant Accidents are usually treated by system codes. Some related issues are now revisited at the CFD scale. In each case the progress of the analysis is summarized and the benefit of the multi-scale approach is shown. (authors)

  15. RACORO continental boundary layer cloud investigations. Part I: Case study development and ensemble large-scale forcings

    SciTech Connect (OSTI)

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; Li, Zhijin; Xie, Shaocheng; Ackerman, Andrew S.; Zhang, Minghua; Khairoutdinov, Marat

    2015-06-19

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, ?, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.

  16. RACORO continental boundary layer cloud investigations. Part I: Case study development and ensemble large-scale forcings

    SciTech Connect (OSTI)

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; Li, Zhijin; Xie, Shaocheng; Ackerman, Andrew S.; Zhang, Minghua; Khairoutdinov, Marat

    2015-06-19

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.

  17. RACORO continental boundary layer cloud investigations. Part I: Case study development and ensemble large-scale forcings

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

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; et al

    2015-06-19

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functionsmore » for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.« less

  18. Hybrid Simulator

    Energy Science and Technology Software Center (OSTI)

    2005-10-15

    HybSim (short for Hybrid Simulator) is a flexible, easy to use screening tool that allows the user to quanti the technical and economic benefits of installing a village hybrid generating system and simulates systems with any combination of —Diesel generator sets —Photovoltaic arrays -Wind Turbines and -Battery energy storage systems Most village systems (or small population sites such as villages, remote military bases, small communities, independent or isolated buildings or centers) depend on diesel generationmore » systems for their source of energy. HybSim allows the user to determine other "sources" of energy that can greatly reduce the dollar to kilo-watt hour ratio. Supported by the DOE, Energy Storage Program, HybSim was initially developed to help analyze the benefits of energy storage systems in Alaskan villages. Soon after its development, other sources of energy were added providing the user with a greater range of analysis opportunities and providing the village with potentially added savings. In addition to village systems, HybSim has generated interest for use from military institutions in energy provisions and USAID for international village analysis.« less

  19. Combustion Stability in Complex Engineering Flows | Argonne Leadership

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

    Computing Facility 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

  20. Analysis of turbulent transport and mixing in transitional Rayleigh/Taylor unstable flow using direct numerical simulation data

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

    Schilling, Oleg; Mueschke, Nicholas J.

    2010-10-18

    energy flux, which changes sign early in time (a countergradient effect). The production-to-dissipation ratios corresponding to the turbulent kinetic energy and heavy-fluid mass fraction variance are large and vary strongly at small evolution times, decrease with time, and nearly asymptote as the flow enters a self-similar regime. The late-time turbulent kinetic energy production-to-dissipation ratio is larger than observed in shear-driven turbulent flows. The order of magnitude estimates of the terms in the transport equations are shown to be consistent with the DNS at late-time, and also confirms both the dominant terms and their evolutionary behavior. These results are useful for identifying the dynamically important terms requiring closure, and assessing the accuracy of the predictions of Reynolds-averaged Navier-Stokes and large-eddy simulation models of turbulent transport and mixing in transitional Rayleigh-Taylor instability-generated flow.less

  1. Using LES to Study Reacting Flows and Instabilities in Annular Combustion

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

    Chambers | Argonne Leadership Computing Facility Using LES to Study Reacting Flows and Instabilities in Annular Combustion Chambers Authors: Staffelbach, G., Wolf, P., Roux, A., Poinsot, T., Balakrishnan, R. Great prominence is put on the design of aeronautical gas turbines due to increasingly stringent regulations and the need to tackle rising fuel prices. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. In the particular field of

  2. DNS/LES of Complex Turbulent Flows | Argonne Leadership Computing Facility

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

    Autoignition of a turbulent hydrogen jet injected into hot oxygen Autoignition of a turbulent hydrogen jet injected into hot oxygen. The green isocontours illustrate the turbulent structures in the fuel, the blue isocontours show the HO2 radical (an important precursor to autoignition), and the orange isosurfaces illustrate temperature. Credit: Rajapadiyan Asaithambi and Krishnan Mahesh, University of Minnesota DNS/LES of Complex Turbulent Flows PI Name: Krishnan Mahesh PI Email: mahesh@umn.edu

  3. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    SciTech Connect (OSTI)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

    2013-12-26

    Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

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

    SciTech Connect (OSTI)

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

    2002-04-30

    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.

  5. Building a Particle Simulator

    SciTech Connect (OSTI)

    Weaver, Brian Phillip; Williams, Brian J.

    2015-10-06

    The purpose of this manuscript is to illustrate how to use the simulator we have developed to generate counts from simulated spectra.

  6. Reframing Accelerator Simulations

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

    Simulations Mori-1.png Key Challenges: Use advanced simulation tools to study the feasibility of plasma-based linear colliders and to optimize conceptual designs. Much of the...

  7. Heavy Vehicle Simulator

    SciTech Connect (OSTI)

    2015-03-09

    Idaho National Laboratory Heavy Vehicle Simulator located at the Center for Advanced Energy Studies.

  8. Subgrid models for mass and thermal diffusion in turbulent mixing

    SciTech Connect (OSTI)

    Sharp, David H; Lim, Hyunkyung; Li, Xiao - Lin; Gilmm, James G

    2008-01-01

    We are concerned with the chaotic flow fields of turbulent mixing. Chaotic flow is found in an extreme form in multiply shocked Richtmyer-Meshkov unstable flows. The goal of a converged simulation for this problem is twofold: to obtain converged solutions for macro solution features, such as the trajectories of the principal shock waves, mixing zone edges, and mean densities and velocities within each phase, and also for such micro solution features as the joint probability distributions of the temperature and species concentration. We introduce parameterized subgrid models of mass and thermal diffusion, to define large eddy simulations (LES) that replicate the micro features observed in the direct numerical simulation (DNS). The Schmidt numbers and Prandtl numbers are chosen to represent typical liquid, gas and plasma parameter values. Our main result is to explore the variation of the Schmidt, Prandtl and Reynolds numbers by three orders of magnitude, and the mesh by a factor of 8 per linear dimension (up to 3200 cells per dimension), to allow exploration of both DNS and LES regimes and verification of the simulations for both macro and micro observables. We find mesh convergence for key properties describing the molecular level of mixing, including chemical reaction rates between the distinct fluid species. We find results nearly independent of Reynolds number for Re 300, 6000, 600K . Methodologically, the results are also new. In common with the shock capturing community, we allow and maintain sharp solution gradients, and we enhance these gradients through use of front tracking. In common with the turbulence modeling community, we include subgrid scale models with no adjustable parameters for LES. To the authors' knowledge, these two methodologies have not been previously combined. In contrast to both of these methodologies, our use of Front Tracking, with DNS or LES resolution of the momentum equation at or near the Kolmogorov scale, but without resolving the

  9. Insights from modeling and observational evaluation of a precipitating continental cumulus event observed during the MC3E field campaign

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

    Mechem, David B.; Giangrande, Scott E.; Wittman, Carly S.; Borque, Paloma; Toto, Tami; Kollias, Pavlos

    2015-03-13

    A case of shallow cumulus and precipitating cumulus congestus sampled at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) supersite is analyzed using a multi-sensor observational approach and numerical simulation. Observations from a new radar suite surrounding the facility are used to characterize the evolving statistical behavior of the precipitating cloud system. This is accomplished using distributions of different measures of cloud geometry and precipitation properties. Large-eddy simulation (LES) with size-resolved (bin) microphysics is employed to determine the forcings most important in producing the salient aspects of the cloud system captured in the radar observations. Our emphasis ismore » on assessing the importance of time-varying vs. steady-state large-scale forcing on the model's ability to reproduce the evolutionary behavior of the cloud system. Additional consideration is given to how the characteristic spatial scale and homogeneity of the forcing imposed on the simulation influences the evolution of cloud system properties. Results indicate that several new scanning radar estimates such as distributions of cloud top are useful to differentiate the value of time-varying (or at least temporally well-matched) forcing on LES solution fidelity.« less

  10. Insights from modeling and observational evaluation of a precipitating continental cumulus event observed during the MC3E field campaign

    SciTech Connect (OSTI)

    Mechem, David B.; Giangrande, Scott E.; Wittman, Carly S.; Borque, Paloma; Toto, Tami; Kollias, Pavlos

    2015-03-13

    A case of shallow cumulus and precipitating cumulus congestus sampled at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) supersite is analyzed using a multi-sensor observational approach and numerical simulation. Observations from a new radar suite surrounding the facility are used to characterize the evolving statistical behavior of the precipitating cloud system. This is accomplished using distributions of different measures of cloud geometry and precipitation properties. Large-eddy simulation (LES) with size-resolved (bin) microphysics is employed to determine the forcings most important in producing the salient aspects of the cloud system captured in the radar observations. Our emphasis is on assessing the importance of time-varying vs. steady-state large-scale forcing on the model's ability to reproduce the evolutionary behavior of the cloud system. Additional consideration is given to how the characteristic spatial scale and homogeneity of the forcing imposed on the simulation influences the evolution of cloud system properties. Results indicate that several new scanning radar estimates such as distributions of cloud top are useful to differentiate the value of time-varying (or at least temporally well-matched) forcing on LES solution fidelity.

  11. Weld arc simulator

    DOE Patents [OSTI]

    Burr, Melvin J.

    1990-01-30

    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.

  12. Electrical Circuit Simulation Code

    Energy Science and Technology Software Center (OSTI)

    2001-08-09

    Massively-Parallel Electrical Circuit Simulation Code. CHILESPICE is a massively-arallel distributed-memory electrical circuit simulation tool that contains many enhanced radiation, time-based, and thermal features and models. Large scale electronic circuit simulation. Shared memory, parallel processing, enhance convergence. Sandia specific device models.

  13. Flow topologies and turbulence scales in a jet-in-cross-flow

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

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensivemore » characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.« less

  14. Flow topologies and turbulence scales in a jet-in-cross-flow

    SciTech Connect (OSTI)

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensive characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.

  15. Air Shower Simulations

    SciTech Connect (OSTI)

    Alania, Marco; Gomez, Adolfo V. Chamorro; Araya, Ignacio J.; Huerta, Humberto Martinez; Flores, Alejandra Parra; Knapp, Johannes

    2009-04-30

    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.

  16. Reactor refueling machine simulator

    SciTech Connect (OSTI)

    Rohosky, T.L.; Swidwa, K.J.

    1987-10-13

    This patent describes in combination: a nuclear reactor; a refueling machine having a bridge, trolley and hoist each driven by a separate motor having feedback means for generating a feedback signal indicative of movement thereof. The motors are operable to position the refueling machine over the nuclear reactor for refueling the same. The refueling machine also has a removable control console including means for selectively generating separate motor signals for operating the bridge, trolley and hoist motors and for processing the feedback signals to generate an indication of the positions thereof, separate output leads connecting each of the motor signals to the respective refueling machine motor, and separate input leads for connecting each of the feedback means to the console; and a portable simulator unit comprising: a single simulator motor; a single simulator feedback signal generator connected to the simulator motor for generating a simulator feedback signal in response to operation of the simulator motor; means for selectively connecting the output leads of the console to the simulator unit in place of the refueling machine motors, and for connecting the console input leads to the simulator unit in place of the refueling machine motor feedback means; and means for driving the single simulator motor in response to any of the bridge, trolley or hoist motor signals generated by the console and means for applying the simulator feedback signal to the console input lead associated with the motor signal being generated by the control console.

  17. Fast Analysis and Simulation Team | NISAC

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

    NISACFast Analysis and Simulation Team

  18. Parallel Atomistic Simulations

    SciTech Connect (OSTI)

    HEFFELFINGER,GRANT S.

    2000-01-18

    Algorithms developed to enable the use of atomistic molecular simulation methods with parallel computers are reviewed. Methods appropriate for bonded as well as non-bonded (and charged) interactions are included. While strategies for obtaining parallel molecular simulations have been developed for the full variety of atomistic simulation methods, molecular dynamics and Monte Carlo have received the most attention. Three main types of parallel molecular dynamics simulations have been developed, the replicated data decomposition, the spatial decomposition, and the force decomposition. For Monte Carlo simulations, parallel algorithms have been developed which can be divided into two categories, those which require a modified Markov chain and those which do not. Parallel algorithms developed for other simulation methods such as Gibbs ensemble Monte Carlo, grand canonical molecular dynamics, and Monte Carlo methods for protein structure determination are also reviewed and issues such as how to measure parallel efficiency, especially in the case of parallel Monte Carlo algorithms with modified Markov chains are discussed.

  19. Device Simulation Tool - JCAP

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

    PAZ0036_v2.jpg Device Simulation Tool Research Why Solar Fuels Goals & Objectives Thrust 1 Thrust 2 Thrust 3 Thrust 4 Publications Research Highlights Videos Innovations User Facilities Expert Team Benchmarking Database Device Simulation Tool XPS Spectral Database Research Introduction Why Solar Fuels? Goals & Objectives Thrusts Thrust 1 Thrust 2 Thrust 3 Thrust 4 Library Publications Research Highlights Videos Resources User Facilities Expert Team Benchmarking Database Device Simulation

  20. Modeling & Simulation publications

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

    Modeling and Simulation in the Chemical Sciences » 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,

  1. Whole Building Energy Simulation

    Broader source: Energy.gov [DOE]

    Whole building energy simulation, also referred to as energy modeling, can and should be incorporated early during project planning to provide energy impact feedback for which design considerations...

  2. Les Houches Physics at TeV Colliders 2005 Beyond the Standard Model Working Group: Summary Report

    SciTech Connect (OSTI)

    Allanach, B.C.; Grojean, C.; Skands, P.; Accomando, E.; Azuelos, G.; Baer, H.; Balazs, C.; Belanger, G.; Benakli, K.; Boudjema, F.; Brelier, B.; Bunichev, V.; Cacciapaglia, G.; Carena, M.; Choudhury, D.; Delsart, P.-A.; De Sanctis, U.; Desch, K.; Dobrescu, B.A.; Dudko, L.; El Kacimi, M.; /Saclay, SPhT /CERN /Fermilab /INFN, Turin /Turin U. /Montreal U. /TRIUMF /Florida State U. /Argonne /Annecy, LAPTH /Paris, LPTHE /Moscow State U. /Cornell U., CIHEP /Delhi U. /Milan U. /INFN, Milan /Freiburg U. /Cadi Ayyad U., Marrakech /Orsay, LPT /Oslo U. /Lancaster U.

    2006-03-17

    The work contained herein constitutes a report of the ''Beyond the Standard Model'' working group for the Workshop ''Physics at TeV Colliders'', Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.

  3. Drizzle production in stratocumulus

    SciTech Connect (OSTI)

    Feingold, G.; Frisch, A.S.; Stevens, B.; Cotton, W.R.

    1996-04-01

    Although stratocumulus clouds are not prodigious producers of precipitation, the small amounts of drizzle they do produce have an important impact on both cloud macrophysical properties (e.g., spatial coverage, depth and liquid water content) and microphysical properties (e.g., droplet size distributions, effective radii). The radiative effects of stratocumulus are intimately connected to both these macro- and microphysical properties, and it is thus essential that we understand the mechanisms of droplet growth which generate precipitation sized droplets. Drizzle production is closely related to cloud condensation nucleus (CCN) number and size, as well as to cloud dynamics and the ability of clouds to support droplets within their bounds and allow for repeated collision-coalesence cycles. In order to address both the microphysical and dynamical aspects of drizzle formation (and their close coupling), we have adapted a large eddy simulation (LES) model to include explicit (size-resolving) microphysical treatment of the CCN and droplet spectra. By directly calculating processes such as droplet growth by condensation and stochastic collection, evaporation, and sedimentation in the LES framework, we are in a position to elucidate the drizzle formation process.

  4. Radiation detector spectrum simulator

    DOE Patents [OSTI]

    Wolf, Michael A.; Crowell, John M.

    1987-01-01

    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.

  5. Radiation detector spectrum simulator

    DOE Patents [OSTI]

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

    1985-04-09

    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.

  6. Radio Channel Simulator (RCSM)

    Energy Science and Technology Software Center (OSTI)

    2007-01-31

    This is a simulation package for making site specific predictions of radio signal strength. The software computes received power at discrete grid points as a function of the transmitter location and propagation environment. It is intended for use with wireless network simulation packages and to support wireless network deployments.

  7. Damselfly Network Simulator

    Energy Science and Technology Software Center (OSTI)

    2014-04-01

    Damselfly is a model-based parallel network simulator. It can simulate communication patterns of High Performance Computing applications on different network topologies. It outputs steady-state network traffic for a communication pattern, which can help in studying network congestion and its impact on performance.

  8. Converting DYNAMO simulations to Powersim Studio simulations

    SciTech Connect (OSTI)

    Walker, La Tonya Nicole; Malczynski, Leonard A.

    2014-02-01

    DYNAMO is a computer program for building and running 'continuous' simulation models. It was developed by the Industrial Dynamics Group at the Massachusetts Institute of Technology for simulating dynamic feedback models of business, economic, and social systems. The history of the system dynamics method since 1957 includes many classic models built in DYANMO. It was not until the late 1980s that software was built to take advantage of the rise of personal computers and graphical user interfaces that DYNAMO was supplanted. There is much learning and insight to be gained from examining the DYANMO models and their accompanying research papers. We believe that it is a worthwhile exercise to convert DYNAMO models to more recent software packages. We have made an attempt to make it easier to turn these models into a more current system dynamics software language, Powersim Studio produced by Powersim AS2 of Bergen, Norway. This guide shows how to convert DYNAMO syntax into Studio syntax.

  9. Analysis of turbulent transport and mixing in transitional Rayleigh–Taylor unstable flow using direct numerical simulation data

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

    Schilling, Oleg; Mueschke, Nicholas J.

    2010-10-18

    energy flux, which changes sign early in time (a countergradient effect). The production-to-dissipation ratios corresponding to the turbulent kinetic energy and heavy-fluid mass fraction variance are large and vary strongly at small evolution times, decrease with time, and nearly asymptote as the flow enters a self-similar regime. The late-time turbulent kinetic energy production-to-dissipation ratio is larger than observed in shear-driven turbulent flows. The order of magnitude estimates of the terms in the transport equations are shown to be consistent with the DNS at late-time, and also confirms both the dominant terms and their evolutionary behavior. Thus, these results are useful for identifying the dynamically important terms requiring closure, and assessing the accuracy of the predictions of Reynolds-averaged Navier-Stokes and large-eddy simulation models of turbulent transport and mixing in transitional Rayleigh-Taylor instability-generated flow.« less

  10. A Multi-Year Plan for Enhancing Turbulence Modeling in Hydra-TH Revised and Updated Version 2.0

    SciTech Connect (OSTI)

    Smith, Thomas M.; Berndt, Markus; Baglietto, Emilio; Magolan, Ben

    2015-10-01

    The purpose of this report is to document a multi-year plan for enhancing turbulence modeling in Hydra-TH for the Consortium for Advanced Simulation of Light Water Reactors (CASL) program. Hydra-TH is being developed to the meet the high- fidelity, high-Reynolds number CFD based thermal hydraulic simulation needs of the program. This work is being conducted within the thermal hydraulics methods (THM) focus area. This report is an extension of THM CASL milestone L3:THM.CFD.P10.02 [33] (March, 2015) and picks up where it left off. It will also serve to meet the requirements of CASL THM level three milestone, L3:THM.CFD.P11.04, scheduled for completion September 30, 2015. The objectives of this plan will be met by: maturation of recently added turbulence models, strategic design/development of new models and systematic and rigorous testing of existing and new models and model extensions. While multi-phase turbulent flow simulations are important to the program, only single-phase modeling will be considered in this report. Large Eddy Simulation (LES) is also an important modeling methodology. However, at least in the first year, the focus is on steady-state Reynolds Averaged Navier-Stokes (RANS) turbulence modeling.

  11. An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

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

    Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

    2016-01-05

    Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

  12. Global Feedback Simulator

    SciTech Connect (OSTI)

    Carlos Serrano, Lawrence Doolittle

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as the ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.

  13. Global Feedback Simulator

    Energy Science and Technology Software Center (OSTI)

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as themore » ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.« less

  14. Fundamentals of plasma simulation

    SciTech Connect (OSTI)

    Forslund, D.W.

    1985-01-01

    With the increasing size and speed of modern computers, the incredibly complex nonlinear properties of plasmas in the laboratory and in space are being successfully explored in increasing depth. Of particular importance have been numerical simulation techniques involving finite size particles on a discrete mesh. After discussing the importance of this means of understanding a variety of nonlinear plasma phenomena, we describe the basic elements of particle-in-cell simulation and their limitations and advantages. The differencing techniques, stability and accuracy issues, data management and optimization issues are discussed by means of a simple example of a particle-in-cell code. Recent advances in simulation methods allowing large space and time scales to be treated with minimal sacrifice in physics are reviewed. Various examples of nonlinear processes successfully studied by plasma simulation will be given.

  15. Compressible Astrophysics Simulation Code

    Energy Science and Technology Software Center (OSTI)

    2007-07-18

    This is an astrophysics simulation code involving a radiation diffusion module developed at LLNL coupled to compressible hydrodynamics and adaptive mesh infrastructure developed at LBNL. One intended application is to neutrino diffusion in core collapse supernovae.

  16. Dynamic Power Grid Simulation

    Energy Science and Technology Software Center (OSTI)

    2015-09-14

    GridDyn is a part of power grid simulation toolkit. The code is designed using modern object oriented C++ methods utilizing C++11 and recent Boost libraries to ensure compatibility with multiple operating systems and environments.

  17. Xyce parallel electronic simulator.

    SciTech Connect (OSTI)

    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.

    2010-05-01

    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.

  18. Modeling & Simulation | NISAC

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

    NISACModeling & Simulation content top Overview Posted by Admin on Feb 13, 2012 in | Comments 0 comments NISAC experts analyze-using modeling and simulation capabilities-critical infrastructure, along with their interdependencies, vulnerabilities, and complexities. Their analyses are used to aid decisionmakers with policy assessment, mitigation planning, education, and training and provide near-real-time assistance to crisis-response organizations. Infrastructure systems are large, complex,

  19. Advanced Simulation and Computing

    National Nuclear Security Administration (NNSA)

    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

  20. Theory Modeling and Simulation

    SciTech Connect (OSTI)

    Shlachter, Jack

    2012-08-23

    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.

  1. Development of capabilities to simulate the coupledthermal-hydrologic...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Conference: GOrdon Research Conference: Flow & Transport in Permeable Media ; 2012-06-24 - 2012-06-29 ; Les Diablerets, Switzerland Research Org: Los Alamos ...

  2. Computer simulation | Open Energy Information

    Open Energy Info (EERE)

    Computer simulation Jump to: navigation, search OpenEI Reference LibraryAdd to library Web Site: Computer simulation Author wikipedia Published wikipedia, 2013 DOI Not Provided...

  3. Development and testing of an aerosol-stratus cloud parameterization scheme for middle and high latitudes

    SciTech Connect (OSTI)

    Olsson, P.Q.; Meyers, M.P.; Kreidenweis, S.; Cotton, W.R.

    1996-04-01

    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/microphysics models. The primary objectives of this work are twofold. First, we need the prediction of number concentrations of activated aerosol which are transferred to the droplet spectrum, so that the aerosol population directly affects the cloud formation and microphysics. Second, we plan to couple the aerosol model to the gas and aqueous-chemistry module that will drive the aerosol formation and growth. We begin by exploring the feasibility of performing cloud-resolving simulations of Arctic stratus clouds over the North Slope CART site. These simulations using Colorado State University`s regional atmospheric modeling system (RAMS) will be useful in designing the structure of the cloud-resolving model and in interpreting data acquired at the North Slope site.

  4. Ion Beam Simulator

    Energy Science and Technology Software Center (OSTI)

    2005-11-08

    IBSimu(Ion Beam Simulator) is a computer program for making two and three dimensional ion optical simulations. The program can solve electrostatic field in a rectangular mesh using Poisson equation using Finite Difference method (FDM). The mesh can consist of a coarse and a fine part so that the calculation accuracy can be increased in critical areas of the geometry, while most of the calculation is done quickly using the coarse mesh. IBSimu can launch ionmore » beam trajectories into the simulation from an injection surface or fomo plasma. Ion beam space charge of time independent simulations can be taken in account using Viasov iteration. Plasma is calculated by compensating space charge with electrons having Boltzmann energy distribution. The simulation software can also be used to calculate time dependent cases if the space charge is not calculated. Software includes diagnostic tools for plotting the geometry, electric field, space charge map, ion beam trajectories, emittance data and beam profiles.« less

  5. SMC curing simulation

    SciTech Connect (OSTI)

    Akiyama, Koichi; Kuroki, Hiroyuki; Matsuda, Terukazu

    1996-11-01

    SMC curing properties are being measured with many kinds of procedures all over the world, and they are the most important factors for molding. But, it is very difficult to predict SMC curing properties because SMC consists of many kinds of ingredients. Measuring temperature in the middle of SMC plies with a thermocouple is so convenient that it is widely adopted to curing properties evaluation. Time-temperature curve involves many factors, for example, thermal conductivity, radical generation and polymerization. SMC curing is affected by combination of these factors. The authors have built a simulation model for SMC curing consisting of seven physicochemical parameters. All parameters in this model can be calculated from time-temperature curves measured at two different molding temperatures. This model can simulate curing properties for any SMC formulations at any different molding temperatures. It can be used to simulate curing properties of molded parts even if parts have any thickness and shapes like ribs and bosses. This means molding can be simulated only using a few data. SMC curing properties can be easily predicted using this simulation program without real measurement. It greatly helps to optimize SMC curing properties and molding condition.

  6. Simple Electric Vehicle Simulation

    Energy Science and Technology Software Center (OSTI)

    1993-07-29

    SIMPLEV2.0 is an electric vehicle simulation code which can be used with any IBM compatible personal computer. This general purpose simulation program is useful for performing parametric studies of electric and series hybrid electric vehicle performance on user input driving cycles.. The program is run interactively and guides the user through all of the necessary inputs. Driveline components and the traction battery are described and defined by ASCII files which may be customized by themore » user. Scaling of these components is also possible. Detailed simulation results are plotted on the PC monitor and may also be printed on a printer attached to the PC.« less

  7. Terascale Optimal PDE Simulations

    SciTech Connect (OSTI)

    David Keyes

    2009-07-28

    The Terascale Optimal PDE Solvers (TOPS) Integrated Software Infrastructure Center (ISIC) was created to develop and implement algorithms and support scientific investigations performed by DOE-sponsored researchers. These simulations often involve the solution of partial differential equations (PDEs) on terascale computers. The TOPS Center researched, developed and deployed an integrated toolkit of open-source, optimal complexity solvers for the nonlinear partial differential equations that arise in many DOE application areas, including fusion, accelerator design, global climate change and reactive chemistry. The algorithms created as part of this project were also designed to reduce current computational bottlenecks by orders of magnitude on terascale computers, enabling scientific simulation on a scale heretofore impossible.

  8. Simulating neural systems with Xyce.

    SciTech Connect (OSTI)

    Schiek, Richard Louis; Thornquist, Heidi K.; Mei, Ting; Warrender, Christina E.; Aimone, James Bradley; Teeter, Corinne; Duda, Alex M.

    2012-12-01

    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.

  9. Battery Particle Simulation

    SciTech Connect (OSTI)

    2014-09-15

    Two simulations show the differences between a battery being drained at a slower rate, over a full hour, versus a faster rate, only six minutes (a tenth of an hour). In both cases battery particles go from being fully charged (green) to fully drained (red), but there are significant differences in the patterns of discharge based on the rate.

  10. Parallel Dislocation Simulator

    Energy Science and Technology Software Center (OSTI)

    2006-10-30

    ParaDiS is software capable of simulating the motion, evolution, and interaction of dislocation networks in single crystals using massively parallel computer architectures. The software is capable of outputting the stress-strain response of a single crystal whose plastic deformation is controlled by the dislocation processes.

  11. PEBBLES Mechanics Simulation Speedup

    SciTech Connect (OSTI)

    Joshua J. Cogliati; Abderrafi M. Ougouag

    2010-05-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. These simulations involve hundreds of thousands of pebbles and involve determining the entire core motion as pebbles are recirculated. Single processor algorithms for this are insufficient since they would take decades to centuries of wall-clock time. This paper describes the process of parallelizing and speeding up the PEBBLES pebble mechanics simulation code. Both shared memory programming with the Open Multi-Processing API and distributed memory programming with the Message Passing Interface API are used in simultaneously in this process. A new shared memory lock-less linear time collision detection algorithm is described. This method allows faster detection of pebbles in contact than generic methods. These combine to make full recirculations on AVR sized reactors possible in months of wall clock time.

  12. A Reconstructed Discontinuous Galerkin Method for the Compressible Navier-Stokes Equations on Hybrid Grids

    SciTech Connect (OSTI)

    Xiaodong Liu; Lijun Xuan; Hong Luo; Yidong Xia

    2001-01-01

    A reconstructed discontinuous Galerkin (rDG(P1P2)) method, originally introduced for the compressible Euler equations, is developed for the solution of the compressible Navier- Stokes equations on 3D hybrid grids. In this method, a piecewise quadratic polynomial solution is obtained from the underlying piecewise linear DG solution using a hierarchical Weighted Essentially Non-Oscillatory (WENO) reconstruction. The reconstructed quadratic polynomial solution is then used for the computation of the inviscid fluxes and the viscous fluxes using the second formulation of Bassi and Reay (Bassi-Rebay II). The developed rDG(P1P2) method is used to compute a variety of flow problems to assess its accuracy, efficiency, and robustness. The numerical results demonstrate that the rDG(P1P2) method is able to achieve the designed third-order of accuracy at a cost slightly higher than its underlying second-order DG method, outperform the third order DG method in terms of both computing costs and storage requirements, and obtain reliable and accurate solutions to the large eddy simulation (LES) and direct numerical simulation (DNS) of compressible turbulent flows.

  13. Direct Numerical Simulation

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

    Direct Numerical Simulation - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced

  14. Advanced Wellbore Thermal Simulator

    Energy Science and Technology Software Center (OSTI)

    1992-03-04

    GEOTEMP2, which is based on the earlier GEOTEMP program, is a wellbore thermal simulator designed for geothermal well drilling and production applications. The code treats natural and forced convection and conduction within the wellbore and heat conduction within the surrounding rock matrix. A variety of well operations can be modeled including injection, production, forward and reverse circulation with gas or liquid, gas or liquid drilling, and two-phase steam injection and production. Well completion with severalmore » different casing sizes and cement intervals can be modeled. The code allows variables, such as flow rate, to change with time enabling a realistic treatment of well operations. Provision is made in the flow equations to allow the flow areas of the tubing to vary with depth in the wellbore. Multiple liquids can exist in GEOTEMP2 simulations. Liquid interfaces are tracked through the tubing and annulus as one liquid displaces another. GEOTEMP2, however, does not attempt to simulate displacement of liquids with a gas or two-phase steam or vice versa. This means that it is not possible to simulate an operation where the type of drilling fluid changes, e.g. mud going to air. GEOTEMP2 was designed primarily for use in predicting the behavior of geothermal wells, but it is flexible enough to handle many typical drilling, production, and injection problems in the oil industry as well. However, GEOTEMP2 does not allow the modeling of gas-filled annuli in production or injection problems. In gas or mist drilling, no radiation losses are included in the energy balance. No attempt is made to model flow in the formation. Average execution time is 50 CP seconds on a CDC CYBER170. This edition of GEOTEMP2 is designated as Version 2.0 by the contributors.« less

  15. Predictive Simulation of Engines

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

    Predictive Simulation of Engines - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs

  16. High Order Seismic Simulations

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

    Order Seismic Simulations on the Intel Xeon Phi Processor (Knights Landing) Alexander Heinecke 1 , Alexander Breuer 2 , Michael Bader 3 , and Pradeep Dubey 1 1 Intel Corporation, 2200 Mission College Blvd., Santa Clara 95054, CA, USA 2 University of California, San Diego, 9500 Gilman Dr., La Jolla 92093, CA, USA 3 Technische Universit¨ at M¨ unchen, Boltzmannstr. 3, D-85748 Garching, Germany Abstract. We present a holistic optimization of the ADER-DG finite element software SeisSol targeting

  17. Fast Analysis and Simulation Team | NISAC

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

    SheetsFast Analysis and Simulation Team content top Fast Analysis and Simulation Team

  18. Les Houches guidebook to Monte Carlo generators for hadron collider physics

    SciTech Connect (OSTI)

    Dobbs, Matt A.; Frixione, Stefano; Laenen, Eric; Tollefson, Kirsten

    2004-03-01

    Recently the collider physics community has seen significant advances in the formalisms and implementations of event generators. This review is a primer of the methods commonly used for the simulation of high energy physics events at particle colliders. We provide brief descriptions, references, and links to the specific computer codes which implement the methods. The aim is to provide an overview of the available tools, allowing the reader to ascertain which tool is best for a particular application, but also making clear the limitations of each tool.

  19. Les Houches Guidebook to Monte Carlo generators for hadron collider physics

    SciTech Connect (OSTI)

    Dobbs, M.A

    2004-08-24

    Recently the collider physics community has seen significant advances in the formalisms and implementations of event generators. This review is a primer of the methods commonly used for the simulation of high energy physics events at particle colliders. We provide brief descriptions, references, and links to the specific computer codes which implement the methods. The aim is to provide an overview of the available tools, allowing the reader to ascertain which tool is best for a particular application, but also making clear the limitations of each tool.

  20. Structural Simulation Toolkit. Lunch & Learn

    SciTech Connect (OSTI)

    Moore, Branden J.; Voskuilen, Gwendolyn Renae; Rodrigues, Arun F.; Hammond, Simon David; Hemmert, Karl Scott

    2015-09-01

    This is a presentation outlining a lunch and learn lecture for the Structural Simulation Toolkit, supported by Sandia National Laboratories.

  1. Look-ahead Dynamic Simulation

    Energy Science and Technology Software Center (OSTI)

    2015-10-20

    Look-ahead dynamic simulation software system incorporates the high performance parallel computing technologies, significantly reduces the solution time for each transient simulation case, and brings the dynamic simulation analysis into on-line applications to enable more transparency for better reliability and asset utilization. It takes the snapshot of the current power grid status, functions in parallel computing the system dynamic simulation, and outputs the transient response of the power system in real time.

  2. Microphysical structure of simulated marine stratocumulus: Effects of physical and numerical approximations

    SciTech Connect (OSTI)

    Stevens, B.; Cotton, W.R.; Feingold, G.

    1996-04-01

    Over the past decade or so the evolution and equilibria of persistent decks of stratocumulus climatologically clinging to the edge of summertime subtropical highs have been an issue of increased scientific inquiry. The particular interest in the microphysical structure of these clouds stems from a variety of hypotheses which suggest that anthropogenic influences or biogenic feedbacks may alter the structure of these clouds in a climatically significant manner. Most of these hypotheses are quite tentative, based as they are on simple formulations of boundary layer structures and interactions between drops and aerosols. This work is concerned with an assessment of the microphysical structure of marine stratocumulus as simulated by an LES-EM model.

  3. Plasma Simulation Program

    SciTech Connect (OSTI)

    Greenwald, Martin

    2011-10-04

    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

  4. simulations | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    simulations NASA features LLNL star-formation simulations These high performance computing (HPC) simulations of star formation account for a broad range of physical processes, including: gravity, supersonic turbulence, hydrodynamics, outflows, magnetic fields, chemistry and ionizing and non-ionizing radiation. Image courtesy of Pak Shing Li/ University

  5. Bio-threat microparticle simulants

    DOE Patents [OSTI]

    Farquar, George Roy; Leif, Roald N

    2012-10-23

    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.

  6. Bio-threat microparticle simulants

    DOE Patents [OSTI]

    Farquar, George Roy; Leif, Roald

    2014-09-16

    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.

  7. Plasma theory and simulation research

    SciTech Connect (OSTI)

    Birdsall, C.K.

    1989-01-01

    Our research group uses both theory and simulation as tools in order to increase the understanding of instabilities, heating, diffusion, transport and other phenomena in plasmas. We also work on the improvement of simulation, both theoretically and practically. Our focus has been more and more on the plasma edge (the sheath''), interactions with boundaries, leading to simulations of whole devices (someday a numerical tokamak).

  8. Fusion Simulation Program

    SciTech Connect (OSTI)

    Project Staff

    2012-02-29

    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.

  9. Distributed Sensors Simulator

    Energy Science and Technology Software Center (OSTI)

    2003-08-30

    The Distributed Sensors Simulator (DSS) is an infrastructure that allows the user to debug and test software for distributed sensor networks without the commitment inherent in using hardware. The flexibility of DSS allows developers and researchers to investigate topological, phenomenological, networking, robustness, and scaling issues; explore arbitrary algorithms for DSNs; and is particularly useful as a proof-of-concept tool. The user provides data on node location and specifications, defines event phenomena, and plugs in the application(s)more » to run. DSS in turn provides the virtual environmental embedding — but exposed to the user like no true embedding could ever be.« less

  10. Energy Simulation Games Lesson

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

    Energy Secretary Talks About SRNL Energy Secretary Talks About SRNL Addthis Description Energy Secretary Talks About SRNL

    Ken Walz Unit Title: Energy Efficiency and Renewable Energy (EERE) Subject: Physical, Env, and Social Sciences Lesson Title: Energy Simulation Games Grade Level(s): 6-12 Lesson Length: 1 hours (+ optional time outside class) Date(s): 7/14/2014 * Learning Goal(s) By the end of this lesson, students will have a deeper understanding of Energy Management, Policy, and Decision

  11. Parameterizing correlations between hydrometeor species in mixed-phase Arctic clouds

    SciTech Connect (OSTI)

    Larson, Vincent E.; Nielsen, Brandon J.; Fan, Jiwen; Ovchinnikov, Mikhail

    2011-08-16

    Mixed-phase Arctic clouds, like other clouds, contain small-scale variability in hydrometeor fields, such as cloud water or snow mixing ratio. This variability may be worth parameterizing in coarse-resolution numerical models. In particular, for modeling processes such as accretion and aggregation, it would be useful to parameterize subgrid correlations among hydrometeor species. However, one difficulty is that there exist many hydrometeor species and many microphysical processes, leading to complexity and computational expense.Existing lower and upper bounds (inequalities) on linear correlation coefficients provide useful guidance, but these bounds are too loose to serve directly as a method to predict subgrid correlations. Therefore, this paper proposes an alternative method that is based on a blend of theory and empiricism. The method begins with the spherical parameterization framework of Pinheiro and Bates (1996), which expresses the correlation matrix in terms of its Cholesky factorization. The values of the elements of the Cholesky matrix are parameterized here using a cosine row-wise formula that is inspired by the aforementioned bounds on correlations. The method has three advantages: 1) the computational expense is tolerable; 2) the correlations are, by construction, guaranteed to be consistent with each other; and 3) the methodology is fairly general and hence may be applicable to other problems. The method is tested non-interactively using simulations of three Arctic mixed-phase cloud cases from two different field experiments: the Indirect and Semi-Direct Aerosol Campaign (ISDAC) and the Mixed-Phase Arctic Cloud Experiment (M-PACE). Benchmark simulations are performed using a large-eddy simulation (LES) model that includes a bin microphysical scheme. The correlations estimated by the new method satisfactorily approximate the correlations produced by the LES.

  12. Confidence in Numerical Simulations

    SciTech Connect (OSTI)

    Hemez, Francois M.

    2015-02-23

    This PowerPoint presentation offers a high-level discussion of uncertainty, confidence and credibility in scientific Modeling and Simulation (M&S). It begins by briefly evoking M&S trends in computational physics and engineering. The first thrust of the discussion is to emphasize that the role of M&S in decision-making is either to support reasoning by similarity or to “forecast,” that is, make predictions about the future or extrapolate to settings or environments that cannot be tested experimentally. The second thrust is to explain that M&S-aided decision-making is an exercise in uncertainty management. The three broad classes of uncertainty in computational physics and engineering are variability and randomness, numerical uncertainty and model-form uncertainty. The last part of the discussion addresses how scientists “think.” This thought process parallels the scientific method where by a hypothesis is formulated, often accompanied by simplifying assumptions, then, physical experiments and numerical simulations are performed to confirm or reject the hypothesis. “Confidence” derives, not just from the levels of training and experience of analysts, but also from the rigor with which these assessments are performed, documented and peer-reviewed.

  13. Energy Simulator Residential Buildings

    Energy Science and Technology Software Center (OSTI)

    1992-02-24

    SERI-RES performs thermal energy analysis of residential or small commercial buildings and has the capability of modeling passive solar equipment such as rock beds, trombe walls, and phase change material. The analysis is accomplished by simulation. A thermal model of the building is created by the user and translated into mathematical form by the program. The mathematical equations are solved repeatedly at time intervals of one hour or less for the period of simulation. Themore » mathematical representation of the building is a thermal network with nonlinear, temperature-dependent controls. A combination of forward finite differences, Jacobian iteration, and constrained optimization techniques is used to obtain a solution. An auxiliary interactive editing program, EDITOR, is included for creating building descriptions. EDITOR checks the validity of the input data and also provides facilities for storing and referencing several types of building description files. Some of the data files used by SERI-RES need to be implemented as direct-access files. Programs are included to convert sequential files to direct-access files and vice versa.« less

  14. Laparoscopic simulation interface

    DOE Patents [OSTI]

    Rosenberg, Louis B.

    2006-04-04

    A method and apparatus for providing high bandwidth and low noise mechanical input and output for computer systems. A gimbal mechanism provides two revolute degrees of freedom to an object about two axes of rotation. A linear axis member is coupled to the gimbal mechanism at the intersection of the two axes of rotation. The linear axis member is capable of being translated along a third axis to provide a third degree of freedom. The user object is coupled to the linear axis member and is thus translatable along the third axis so that the object can be moved along all three degrees of freedom. Transducers associated with the provided degrees of freedom include sensors and actuators and provide an electromechanical interface between the object and a digital processing system. Capstan drive mechanisms transmit forces between the transducers and the object. The linear axis member can also be rotated about its lengthwise axis to provide a fourth degree of freedom, and, optionally, a floating gimbal mechanism is coupled to the linear axis member to provide fifth and sixth degrees of freedom to an object. Transducer sensors are associated with the fourth, fifth, and sixth degrees of freedom. The interface is well suited for simulations of medical procedures and simulations in which an object such as a stylus or a joystick is moved and manipulated by the user.

  15. NII Simulator 1.0

    Energy Science and Technology Software Center (OSTI)

    2009-12-02

    The software listed here is a simulator for SAIC P7500 VACIS non intrusive inspection system. The simulator provides messages similar to those provided by this piece of equipment.To facilitate testing of the Second Line of Defense systems and similar software products from commercial software vendors, this software simulation application has been developed to simulate the P7500 that the Second Line of Defense communications software system must interface with. The primary use of this simulator ismore » for testing of both Sandia developed and DOE contractor developed software.« less

  16. NII Simulator 1.0

    SciTech Connect (OSTI)

    Jorgensen, Craig; Salazar, Anthony; Humphrey, Walter; & Johnson, ALfred

    2009-12-02

    The software listed here is a simulator for SAIC P7500 VACIS non intrusive inspection system. The simulator provides messages similar to those provided by this piece of equipment.To facilitate testing of the Second Line of Defense systems and similar software products from commercial software vendors, this software simulation application has been developed to simulate the P7500 that the Second Line of Defense communications software system must interface with. The primary use of this simulator is for testing of both Sandia developed and DOE contractor developed software.

  17. Transportation Anslysis Simulation System

    Energy Science and Technology Software Center (OSTI)

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not

  18. VHDL Control Routing Simulator

    Energy Science and Technology Software Center (OSTI)

    1995-07-10

    The control router simulates a backplane consisting of up to 16 slot. Slot 0, reserved for a control module (cr-ctrl), generates the system clocks and provides the serial interface to the Gating Logic. The remaining 15 slots (1-15) contain routing modules (cr mod), each having up to 64 serial inputs and outputs with FIFOs. Messages to be transmitted to the Control Router are taken from text files. There are currently 17 such source files. Inmore » the model, the serial output of each source is connected to multiple receivers, so that there are 8 identical messages transmitted to the router for each message file entry.« less

  19. PV Hourly Simulation Tool

    Energy Science and Technology Software Center (OSTI)

    2010-12-31

    This software requires inputs of simple general building characteristics and usage information to calculate the energy and cost benefits of solar PV. This tool conducts and complex hourly simulation of solar PV based primarily on the area available on the rooftop. It uses a simplified efficiency calculation method and real panel characteristics. It includes a detailed rate structure to account for time-of-use rates, on-peak and off-peak pricing, and multiple rate seasons. This tool includes themore » option for advanced system design inputs if they are known. This tool calculates energy savings, demand reduction, cost savings, incentives and building life cycle costs including: simple payback, discounted payback, net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.« less

  20. The selection of turbulence models for prediction of room airflow

    SciTech Connect (OSTI)

    Nielsen, P.V.

    1998-10-01

    The airflow in buildings involves a combination of many different flow elements. It is, therefore, difficult to find an adequate, all-round turbulence model covering all aspects. Consequently, it is appropriate and economical to choose turbulence models according to the situation that is to be predicted. This paper discusses the use of different turbulence models and their advantages in given situations. As an example, it is shown that a simple zero-equation model can be used for the prediction of special situations as flow with a low level of turbulence. A zero-equation model with compensation for room dimensions and velocity level also is discussed. A {kappa}-{epsilon} model expanded by damping functions is used to improve the prediction of the flow in a room ventilated by displacement ventilation. The damping functions especially take into account the turbulence level and the vertical temperature gradient. Low Reynolds number models (LNR models) are used to improve the prediction of evaporation-controlled emissions from building material, which is shown by an example. Finally, large eddy simulation (LES) of room airflow is discussed and demonstrated.

  1. A new subgrid-scale representation of hydrometeor fields using a multivariate PDF

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

    Griffin, Brian M.; Larson, Vincent E.

    2016-06-03

    The subgrid-scale representation of hydrometeor fields is important for calculating microphysical process rates. In order to represent subgrid-scale variability, the Cloud Layers Unified By Binormals (CLUBB) parameterization uses a multivariate probability density function (PDF). In addition to vertical velocity, temperature, and moisture fields, the PDF includes hydrometeor fields. Previously, hydrometeor fields were assumed to follow a multivariate single lognormal distribution. Now, in order to better represent the distribution of hydrometeors, two new multivariate PDFs are formulated and introduced.The new PDFs represent hydrometeors using either a delta-lognormal or a delta-double-lognormal shape. The two new PDF distributions, plus the previous single lognormalmore » shape, are compared to histograms of data taken from large-eddy simulations (LESs) of a precipitating cumulus case, a drizzling stratocumulus case, and a deep convective case. Finally, the warm microphysical process rates produced by the different hydrometeor PDFs are compared to the same process rates produced by the LES.« less

  2. Non-detonable explosive simulators

    DOE Patents [OSTI]

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

    1994-11-01

    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.

  3. The promise of quantum simulation

    SciTech Connect (OSTI)

    Muller, Richard P.; Blume-Kohout, Robin

    2015-07-21

    In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.

  4. Lubricant characterization by molecular simulation

    SciTech Connect (OSTI)

    Moore, J.D.; Cui, S.T.; Cummings, P.T.; Cochran, H.D.

    1997-12-01

    The authors have reported the calculation of the kinematic viscosity index of squalane from nonequilibrium molecular dynamics simulations. This represents the first accurate quantitative prediction of this measure of lubricant performance by molecular simulation. Using the same general alkane potential model, this computational approach offers the possibility of predicting the performance of potential lubricants prior to synthesis. Consequently, molecular simulation is poised to become an important tool for future lubricant development.

  5. The promise of quantum simulation

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

    Muller, Richard P.; Blume-Kohout, Robin

    2015-07-21

    In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.

  6. Welcome - Modeling and Simulation Group

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

    CCS Directorate ORNL Modeling and Simulation Group Computational Sciences & Engineering Division Home Organization Chart Staff Research Areas Major Projects Fact Sheets Publications M&S News Awards Contacts Intership Programs ORNL has lots of opportunities for students to conduct research in scientific fields. Check out our Fellowship and Intership programs Fellowships Interships RAMS Program Modeling and Simulation Group The ORNL Modeling and Simulation Group (MSG) develops

  7. Non-detonable explosive simulators

    DOE Patents [OSTI]

    Simpson, Randall L.; Pruneda, Cesar O.

    1994-01-01

    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.

  8. BERNAS ION SOURCE DISCHARGE SIMULATION

    SciTech Connect (OSTI)

    RUDSKOY,I.; KULEVOY, T.V.; PETRENKO, S.V.; KUIBEDA, R.P.; SELEZNEV, D.N.; PERSHIN, V.I.; HERSHCOVITCH, A.; JOHNSON, B.M.; GUSHENETS, V.I.; OKS, E.M.; POOLE, H.J.

    2007-08-26

    The joint research and development program is continued to develop steady-state ion source of decaborane beam for ion implantation industry. Bemas ion source is the wide used ion source for ion implantation industry. The new simulation code was developed for the Bemas ion source discharge simulation. We present first results of the simulation for several materials interested in semiconductors. As well the comparison of results obtained with experimental data obtained at the ITEP ion source test-bench is presented.

  9. Parallel Power Grid Simulation Toolkit

    Energy Science and Technology Software Center (OSTI)

    2015-09-14

    ParGrid is a 'wrapper' that integrates a coupled Power Grid Simulation toolkit consisting of a library to manage the synchronization and communication of independent simulations. The included library code in ParGid, named FSKIT, is intended to support the coupling multiple continuous and discrete even parallel simulations. The code is designed using modern object oriented C++ methods utilizing C++11 and current Boost libraries to ensure compatibility with multiple operating systems and environments.

  10. A stochastic extension of the explicit algebraic subgrid-scale models

    SciTech Connect (OSTI)

    Rasam, A. Brethouwer, G.; Johansson, A. V.

    2014-05-15

    The explicit algebraic subgrid-scale (SGS) stress model (EASM) of Marstorp et al. [Explicit algebraic subgrid stress models with application to rotating channel flow, J. Fluid Mech. 639, 403432 (2009)] and explicit algebraic SGS scalar flux model (EASFM) of Rasam et al. [An explicit algebraic model for the subgrid-scale passive scalar flux, J. Fluid Mech. 721, 541577 (2013)] are extended with stochastic terms based on the Langevin equation formalism for the subgrid-scales by Marstorp et al. [A stochastic subgrid model with application to turbulent flow and scalar mixing, Phys. Fluids 19, 035107 (2007)]. The EASM and EASFM are nonlinear mixed and tensor eddy-diffusivity models, which improve large eddy simulation (LES) predictions of the mean flow, Reynolds stresses, and scalar fluxes of wall-bounded flows compared to isotropic eddy-viscosity and eddy-diffusivity SGS models, especially at coarse resolutions. The purpose of the stochastic extension of the explicit algebraic SGS models is to further improve the characteristics of the kinetic energy and scalar variance SGS dissipation, which are key quantities that govern the small-scale mixing and dispersion dynamics. LES of turbulent channel flow with passive scalar transport shows that the stochastic terms enhance SGS dissipation statistics such as length scale, variance, and probability density functions and introduce a significant amount of backscatter of energy from the subgrid to the resolved scales without causing numerical stability problems. The improvements in the SGS dissipation predictions in turn enhances the predicted resolved statistics such as the mean scalar, scalar fluxes, Reynolds stresses, and correlation lengths. Moreover, the nonalignment between the SGS stress and resolved strain-rate tensors predicted by the EASM with stochastic extension is in much closer agreement with direct numerical simulation data.