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1

Computational Fluid Dynamics (CFD) Simulation of Air Dense ...  

Science Conference Proceedings (OSTI)

In current study, the experimental results of coal beneficiation in a cylindrical bed are used to set up and evaluate the results of a CFD simulation software.

2

Computational fluid dynamics (CFD) simulations of aerosol in a u-shaped steam generator tube  

E-Print Network (OSTI)

To quantify primary side aerosol retention, an Eulerian/Lagrangian approach was used to investigate aerosol transport in a compressible, turbulent, adiabatic, internal, wall-bounded flow. The ARTIST experimental project (Phase I) served as the physical model replicated for numerical simulation. Realizable k-? and standard k-? turbulence models were selected from the computational fluid dynamics (CFD) code, FLUENT, to provide the Eulerian description of the gaseous phase. Flow field simulation results exhibited: a) onset of weak secondary flow accelerated at bend entrance towards the inner wall; b) flow separation zone development on the convex wall that persisted from the point of onset; c) centrifugal force concentrated high velocity flow in the direction of the concave wall; d) formation of vortices throughout the flow domain resulted from rotational (Dean-type) flow; e) weakened secondary flow assisted the formation of twin vortices in the outflow cross section; and f) perturbations induced by the bend influenced flow recovery several pipe diameters upstream of the bend. These observations were consistent with those of previous investigators. The Lagrangian discrete random walk model, with and without turbulent dispersion, simulated the dispersed phase behavior, incorrectly. Accurate deposition predictions in wall-bounded flow require modification of the Eddy Impaction Model (EIM). Thus, to circumvent shortcomings of the EIM, the Lagrangian time scale was changed to a wall function and the root-mean-square (RMS) fluctuating velocities were modified to account for the strong anisotropic nature of flow in the immediate vicinity of the wall (boundary layer). Subsequent computed trajectories suggest a precision that ranges from 0.1% to 0.7%, statistical sampling error. The aerodynamic mass median diameter (AMMD) at the inlet (5.5 ?m) was consistent with the ARTIST experimental findings. The geometric standard deviation (GSD) varied depending on the scenario evaluated but ranged from 1.61 to 3.2. At the outlet, the computed AMMD (1.9 ?m) had GSD between 1.12 and 2.76. Decontamination factors (DF), computed based on deposition from trajectory calculations, were just over 3.5 for the bend and 4.4 at the outlet. Computed DFs were consistent with expert elicitation cited in NUREG-1150 for aerosol retention in steam generators.

Longmire, Pamela

2007-05-01T23:59:59.000Z

3

A CFD Model for Simulating Urban Flow and Dispersion  

Science Conference Proceedings (OSTI)

A three-dimensional computational fluid dynamics (CFD) model is developed to simulate urban flow and dispersion, to understand fluid dynamical processes therein, and to provide practical solutions to some emerging problems of urban air pollution. ...

Jong-Jin Baik; Jae-Jin Kim; Harindra J. S. Fernando

2003-11-01T23:59:59.000Z

4

CFD Modeling and Simulation in Materials Processing  

Science Conference Proceedings (OSTI)

Jul 31, 2011 ... A Coupled CFD-Thermodynamic-Kinetic Model to Simulate a Gas Stirred ... on Thermal and Thermosolutal Natural Convection in Liquid Alloys.

5

Using a CFD simulation in designing a smoke management system in a building  

Science Conference Proceedings (OSTI)

This paper presents a study on the effectiveness of a smoke exhaust system in a complex building using the Computational Fluid Dynamics (CFD) models. The CFD model FDS (Fire Dynamics Simulator) was used for this study. To simulate fires in the building ...

George Hadjisophocleous; Yoon J. Ko

2006-12-01T23:59:59.000Z

6

Gasification CFD Modeling for Advanced Power Plant Simulations  

Science Conference Proceedings (OSTI)

In this paper we have described recent progress on developing CFD models for two commercial-scale gasifiers, including a two-stage, coal slurry-fed, oxygen-blown, pressurized, entrained-flow gasifier and a scaled-up design of the PSDF transport gasifier. Also highlighted was NETL’s Advanced Process Engineering Co-Simulator for coupling high-fidelity equipment models with process simulation for the design, analysis, and optimization of advanced power plants. Using APECS, we have coupled the entrained-flow gasifier CFD model into a coal-fired, gasification-based FutureGen power and hydrogen production plant. The results for the FutureGen co-simulation illustrate how the APECS technology can help engineers better understand and optimize gasifier fluid dynamics and related phenomena that impact overall power plant performance.

Zitney, S.E.; Guenther, C.P.

2005-09-01T23:59:59.000Z

7

Numerical simulation of the air flow field in a laboratory fume hood using the CFD-ACE(TM) computational fluid dynamics code  

E-Print Network (OSTI)

The purpose of this research was the numerical simulation of the air flow field within a standard laboratory fume hood using the k-6 turbulence model. The study investigated the flow field at different sash openings. The results of the computation realized information on the hood entry losses and other design parameters that are of interest to the users, designers and owners of fume hoods. After the specification of the problem and generation of the mesh, the modeled hood was simulated using CFD-ACE TM , a commercial computational fluid dynamics software package. The code is based on the finite volume method. In defining the grid, due care was exercised in maintaining the cell aspect ratio and grid orthogonality within the recommended limits. The air flow patterns at full open sash compared favorably with experimental results. The results at lowered sash revealed air flow characteristics and slot volume flows that were not reported in previously published literature on fume hoods. These results along with smaller hood entry losses confirmed the better performance of fume hoods at sash openings that are less than half open. Further, comparison between the computed volume flow rates and published design data was favorable.

D'Sousa, Cedric Benedict

1997-01-01T23:59:59.000Z

8

Demonstration of a Computational Fluid Dynamics (CFD) Tool Used...  

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

Demonstration of a Computational Fluid Dynamics (CFD) Tool Used for Data Center Modeling, Thermal Analysis and Operational Management Speaker(s): Saket Karajgikar Date: November...

9

CFD Simulation of Airflow in Ventilated Wall System Report #9  

DOE Green Energy (OSTI)

The objective of this report was to examine air movements in vinyl and brick ventilation cavities in detail, using a state of the art CFD commercial modeling tool. The CFD activity was planned to proceed the other activities in order to develop insight on the important magnitudes of scales occurring during ventilation air flow. This information generated by the CFD model was to be used to modify (if necessary) and to validate the air flow dynamics already imbedded in the hygrothermal model for the computer-based air flow simulation procedures. A comprehensive program of advanced, state-of-the-art hygrothermal modeling was then envisaged mainly to extend the knowledge to other wall systems and at least six representative climatic areas. These data were then to be used to provide the basis for the development of design guidelines. CFD results provided timely and much needed answers to many of the concerns and questions related to ventilation flows due to thermal buoyancy and wind-driven flow scenarios. The relative strength between these two mechanisms. Simple correlations were developed and are presented in the report providing the overall pressure drop, and flow through various cavities under different exterior solar and temperature scenarios. Brick Rainscreen Wall: It was initially expected that a 50 mm cavity would offer reduced pressure drops and increased air flow compared to a 19 mm cavity. However, these models showed that the size of the ventilation slots through the wall are the limiting factor rather than the cavity depth. Of course, once the slots are enlarged beyond a certain point, this could change. The effects of natural convection within the air cavities, driven by the temperature difference across the cavity, were shown to be less important than the external wind speed (for a wind direction normal to the wall surface), when wind action is present. Vinyl Rainscreen Wall: The CFD model of the vinyl rainscreen wall was simpler than that for the brick wall. Constant wall temperatures were used rather than conjugate heat transfer. Although this is appropriate for a thin surface with little heat capacity, it does mean that an empirical correlation between solar radiation (and perhaps wind speed) and vinyl temperature is required to use these results appropriately. The results developed from this CFD model were correlated to weather parameters and construction details so that they can be incorporated into ORNL s advanced hygrothermal models MOISTURE- EXPERT.

Stovall, Therese K [ORNL; Karagiozis, Achilles N [ORNL

2004-01-01T23:59:59.000Z

10

Original papers: Aerodynamic analysis and CFD simulation of several cellulose evaporative cooling pads used in Mediterranean greenhouses  

Science Conference Proceedings (OSTI)

The present work makes an aerodynamic analysis and computational fluid dynamics (CFD) simulation of the four commercial models of corrugated cellulose evaporative cooling pads that are most widely used in Mediterranean greenhouses. The geometric characteristics ... Keywords: Aerodynamic analysis, CFD, Evaporative cooling, Fan and pad, Greenhouse, Pressure drop

A. Franco; D. L. Valera; A. Peña; A. M. Pérez

2011-05-01T23:59:59.000Z

11

Multiscale CFD simulations of entrained flow gasification  

E-Print Network (OSTI)

The design of entrained flow gasifiers and their operation has largely been an experience based enterprise. Most, if not all, industrial scale gasifiers were designed before it was practical to apply CFD models. Moreover, ...

Kumar, Mayank, Ph. D. Massachusetts Institute of Technology

2011-01-01T23:59:59.000Z

12

CFD Simulation and Experimental Testing of Multiphase Flow Inside the MVP Electrical Submersible Pump  

E-Print Network (OSTI)

The MVP is a special type of Electrical Submersible Pumps (ESPs) manufactured by Baker Hughes, model no. G470, and is capable of handling multiphase flow up to 70% Gas Volume Fraction (GVF). Flows at high GVF cause conventional ESPs to surge. However, the special design of the impeller blades of the MVP ESP enables it to handle higher GVF. Dynamic behavior of the multiphase flow is studied experimentally and theoretically for this pump for the first time. In this work, a Computational Fluid Dynamics (CFD) simulation of an entire pump and detailed experimental analysis are performed. Meshing and CFD simulations are performed using the commercially available software ANSYS Fluent. An experimental facility has been designed and constructed to test the pump at different operating conditions. The pump is modeled and tested at two speeds; 3300 and 3600 rpm, using air-water mixtures with GVFs of 0, 5, 10, 25, 32 and 35%. The flow loop is controlled to produce different suction pressures up to 300psi. Pump pressure head is used to validate the CFD model for both single and two phase flows. Single phase CFD model was validated at 100 psi inlet pressure, while two phase models were validated at 200 psi inlet pressure. CFD simulations can predict the behavior of the pump at different speeds, flow rates, GVFs, and inlet pressures. Different diffuser designs are studied and simulated to improve the multistage pump performance. Enhanced diffuser designs increased the pump pressure head to up to 3.2%.

Rasmy Marsis, Emanuel 1983-

2012-12-01T23:59:59.000Z

13

CFD Simulation of Infiltration Heat Recovery  

E-Print Network (OSTI)

residential buildings with dynamic insulation”, 16* AIVCas dynamic insulation, air is drawn through the building

Buchanan, C.R.

2011-01-01T23:59:59.000Z

14

Advanced process engineering co-simulation using CFD-based reduced order models  

Science Conference Proceedings (OSTI)

The process and energy industries face the challenge of designing the next generation of plants to operate with unprecedented efficiency and near-zero emissions, while performing profitably amid fluctuations in costs for raw materials, finished products, and energy. To achieve these targets, the designers of future plants are increasingly relying upon modeling and simulation to create virtual plants that allow them to evaluate design concepts without the expense of pilot-scale and demonstration facilities. Two of the more commonly used simulation tools include process simulators for describing the entire plant as a network of simplified equipment models and computational fluid dynamic (CFD) packages for modeling an isolated equipment item in great detail by accounting for complex thermal and fluid flow phenomena. The Advanced Process Engineering Co-Simulator (APECS) sponsored by the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has been developed to combine process simulation software with CFD-based equipment simulation software so that design engineers can analyze and optimize the coupled fluid flow, heat and mass transfer, and chemical reactions that drive overall plant performance (Zitney et al., 2006). The process/CFD software integration was accomplished using the process-industry standard CAPE-OPEN interfaces.

Lang, Y.-D.; Biegler, L.T.; Munteanu, S.; Madsen, J.I.; Zitney, S.E.

2007-11-04T23:59:59.000Z

15

Radiation-cooled Dew Water Condensers Studied by Computational Fluid Dynamic (CFD)  

E-Print Network (OSTI)

Harvesting condensed atmospheric vapour as dew water can be an alternative or complementary potable water resource in specific arid or insular areas. Such radiation-cooled condensing devices use already existing flat surfaces (roofs) or innovative structures with more complex shapes to enhance the dew yield. The Computational Fluid Dynamic - CFD - software PHOENICS has been programmed and applied to such radiation cooled condensers. For this purpose, the sky radiation is previously integrated and averaged for each structure. The radiative balance is then included in the CFD simulation tool to compare the efficiency of the different structures under various meteorological parameters, for complex or simple shapes and at various scales. It has been used to precise different structures before construction. (1) a 7.32 m^2 funnel shape was studied; a 30 degree tilted angle (60 degree cone half-angle) was computed to be the best compromise for funnel cooling. Compared to a 1 m^2 flat condenser, the cooling efficienc...

Clus, O; Muselli, M; Nikolayev, Vadim; Sharan, Girja; Beysens, D

2007-01-01T23:59:59.000Z

16

Molecular Dynamics Simulations of Vacancy and Oxygen Diffusion ...  

Science Conference Proceedings (OSTI)

A Tale of Two States and More: Modeling of New Generation of Lattice Stability from Zero ... Analysis of Nano Fluid Using CFD-A Hybrid Approach for Cooling Purpose ... Molecular Dynamics Simulations of Grain Boundary Free Energy and

17

CFD Simulation and Measurement Validation of Air Distribution at the Hunan International Exhibition Center  

E-Print Network (OSTI)

The Hunan International Exhibition Center (HIEC) is a large space building. A stratified air-conditioning system on the second floor of the building has been adopted. Due to some problems with the air supply jet diffuser, CFD simulations were carried out to predict air distribution. Meanwhile, field measurement results were used to validate the CFD simulation results. A good agreement of simulated and test results was obtained. Based on simulation results, some analyses and suggestions are put forward to improve air distribution.

Deng, T.; Zhang, Q.; Zhang, G.; Yuan, H.

2006-01-01T23:59:59.000Z

18

A CFD simulation on how the different sizes of silica gel will affect the adsorption performance of silica gel  

Science Conference Proceedings (OSTI)

The application of computational fluid dynamics (CFD) in the area of porous media and adsorption cooling system is becoming more practical due to the significant improvement in computer power. The results from previous studies have shown that CFD can ...

John White

2012-01-01T23:59:59.000Z

19

Using Process/CFD Co-Simulation for the Design and Analysis of Advanced Energy Systems  

Science Conference Proceedings (OSTI)

In this presentation we describe the major features and capabilities of NETL’s Advanced Process Engineering Co-Simulator (APECS) and highlight its application to advanced energy systems, ranging from small fuel cell systems to commercial-scale power plants including the coal-fired, gasification-based electricity and hydrogen plant in the DOE’s $1 billion, 10-year FutureGen demonstration project. APECS is an integrated software suite which allows the process and energy industries to optimize overall plant performance with respect to complex thermal and fluid flow phenomena by combining process simulation (e.g., Aspen Plus®) with high-fidelity equipment simulations based on computational fluid dynamics (CFD) models (e.g., FLUENT®).

Zitney, S.E.

2007-04-01T23:59:59.000Z

20

Performance Evaluation and CFD Simulation of Multiphase Twin-Screw Pumps  

E-Print Network (OSTI)

Twin-screw pumps are economical alternatives to the conventional multiphase system and are increasingly used in the oil and gas industry due to their versatility in transferring the multiphase mixture with varying Gas Void Fraction (GVF). Present work focuses on the experimental and numerical analysis of twin-screw pumps for different operating conditions. Experimental evaluation aims to understand steady state and transient behavior of twin-screw pumps. Detailed steady state evaluation helped form better understanding of twin-screw pumps under different operating conditions. A comparative study of twin-screw pumps and compressors contradicted the common belief that compressor efficiency is better than the efficiency of twin-screw pumps. Transient analysis at high GVF helped incorporate necessary changes in the design of sealflush recirculation loop to improve the efficiency of the pump. The effect of viscosity of the sealflush fluid at high GVF on pump performance was studied. Volumetric efficiency was found to be decreased with increase in viscosity. Flow visualization was aimed to characterize phase distribution along cavities and clearances at low to high GVF. Dynamic pressure variation was studied along the axis of the screw which helped correlate the GVF, velocity and pressure distribution. Complicated fluid flow behavior due to enclosed fluid pockets and interconnecting clearances makes it difficult to numerically simulate the pump. Hence design optimization and performance prediction incorporates only analytical approach and experimental evaluation. Current work represents an attempt to numerically simulate a multiphase twin-screw pump as a whole. Single phase 3D CFD simulation was performed for different pressure rise. The pressure and velocity profile agreed well with previous studies. Results are validated using an analytical approach as well as experimental data. A two-phase CFD simulation was performed for 50% GVF. An Eulerian approach was employed to evaluate multiphase flow behavior. Pressure, velocity, temperature and GVF distributions were successfully predicted using CFD simulation. Bubble size was found to be most dominant parameter, significantly affecting phase separation and leakage flow rate. Better phase separation was realized with increased bubble size, which resulted in decrease in leakage flow rate. CFD results agreed well with experimental data for the bubble size higher than 0.08 mm.

Patil, Abhay

2013-08-01T23:59:59.000Z

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


21

Computational fluid dynamic (CFD) optimization of microfluidic mixing in a MEMS steam generator  

E-Print Network (OSTI)

The challenge of achieving rapid mixing in microchannels is addressed through a computational fluid dynamics (CFD) study using the ADINA-F finite element program. The study is motivated by the need to design an adequate ...

Collins, Kimberlee C. (Kimberlee Chiyoko)

2008-01-01T23:59:59.000Z

22

Two-dimensional computational fluid dynamics and conduction simulations of heat transfer in window frames with internal cavities - Part 1: Cavities only  

E-Print Network (OSTI)

of heat fluxes from CFD and conduction simulations for theapproach to solve the conduction heat-transfer equation. TheFluid Dynamics and Conduction Simulations of Heat Transfer

Gustavsen, Arild; Kohler, Christian; Arasteh, Dariush; Curcija, Dragan

2003-01-01T23:59:59.000Z

23

Comparison between experiments and CFD predictions of mixed convection...  

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

results from a computational fluid dynamics (CFD) simulation of airflow and pollutant dispersion under mixed-convection conditions with experimental data obtained in our 7m x...

24

Simulation of Tailrace Hydrodynamics Using Computational Fluid Dynamics Models  

DOE Green Energy (OSTI)

This report investigates the feasibility of using computational fluid dynamics (CFD) tools to investigate hydrodynamic flow fields surrounding the tailrace zone below large hydraulic structures. Previous and ongoing studies using CFD tools to simulate gradually varied flow with multiple constituents and forebay/intake hydrodynamics have shown that CFD tools can provide valuable information for hydraulic and biological evaluation of fish passage near hydraulic structures. These studies however are incapable of simulating the rapidly varying flow fields that involving breakup of the free-surface, such as those through and below high flow outfalls and spillways. Although the use of CFD tools for these types of flow are still an active area of research, initial applications discussed in this report show that these tools are capable of simulating the primary features of these highly transient flow fields.

Cook, Chris B; Richmond, Marshall C

2001-05-01T23:59:59.000Z

25

The past, present and future of CFD for agro-environmental applications  

Science Conference Proceedings (OSTI)

Computational fluid dynamics (CFD) is a proven simulation tool which caters to almost any field of study. The CFD technique is utilized to simulate, analyze, and optimize various engineering designs. In this review, the discussion is focused on the application ... Keywords: Agriculture, Air, CFD, Environment, Soil, Water

In-Bok Lee; Jessie Pascual P. Bitog; Se-Woon Hong; Il-Hwan Seo; Kyeong-Seok Kwon; Thomas Bartzanas; Murat Kacira

2013-04-01T23:59:59.000Z

26

Developing an integrated building design tool by coupling building energy simulation and computational fluid dynamics programs  

E-Print Network (OSTI)

Building energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing essential information to help design energy-efficient, thermally comfortable and healthy ...

Zhai, Zhiqiang, 1971-

2003-01-01T23:59:59.000Z

27

CFD SIMULATION OF PROPOSED VALIDATION DATA FOR A FLOW PROBLEM RECONFIGURED TO ELIMINATE AN UNDESIRABLE FLOW INSTABILITY  

DOE Green Energy (OSTI)

The U. S. Department of Energy (DOE) is supporting the development of a next generation nuclear plant (NGNP), which will be based on a very high temperature reactor (VHTR) design. The VHTR is a single-phase helium-cooled reactor wherein the helium will be heated initially to 750 °C and later to temperatures approaching 1000 °C. The high temperatures are desired to increase reactor efficiency and to provide a heat source for the manufacture of hydrogen and other applications. While computational fluid dynamics (CFD) has not been used in the past to design or license nuclear reactors in the U. S., it is expected that CFD will be used in the design and safety analysis of forthcoming designs. This is partly because of the maturity of CFD and partly because detailed information is desired of the flow and heat transfer inside the reactor to avoid hot spots and other conditions that might compromise reactor safety. Numerical computations of turbulent flow should be validated against experimental data for flow conditions that contain some or all of the physics expected in the thermal fluid machinery of interest. To this end, a scaled model of a narrow slice of the lower plenum of the prismatic VHTR was constructed and installed in the Idaho National Laboratory’s (INL) matched index of refraction (MIR) test facility and data were taken. The data were then studied and compared to CFD calculations to help determine their suitability for validation data. One of the main findings was that the inlet data, which were measured and controlled by calibrated mass flow rotameters and were also measured using detailed stereo particle image velocimetry (PIV) showed considerable discrepancies in mass flow rate between the two methods. The other finding was that a randomly unstable recirculation zone occurs in the flow. This instability has a very significant effect on the flow field in the vicinity of the inlet jets. Because its time scale is long and because it is apparently a random instability, it was deemed undesirable for a validation data set. It was predicted using CFD that by eliminating the first of the four jets, the recirculation zone could be stabilized. The present paper reports detailed results for the three-jet case with comparisons to the four-jet data inasmuch as three-jet data are still unavailable. Hence, the present simulations are true or blind predictions.

Richard W. Johnson; Hugh M. McIlroy

2010-08-01T23:59:59.000Z

28

Demonstration of a Computational Fluid Dynamics (CFD) Tool Used for Data  

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

Demonstration of a Computational Fluid Dynamics (CFD) Tool Used for Data Demonstration of a Computational Fluid Dynamics (CFD) Tool Used for Data Center Modeling, Thermal Analysis and Operational Management Speaker(s): Saket Karajgikar Date: November 11, 2010 - 12:00pm Location: 90-3122 Seminar Host/Point of Contact: Henry Coles Every Data Center built today is designed with a total capacity in mind, as well as a plan to grow into this final-day load. On a daily basis, Data Center Operations/Management professionals work toward keeping their Data Center as close to this plan as possible by concurrently managing the available power, space, cooling and airflow resources. Unfortunately, lack of communication and information, the pace of change and difficulty in coping with the ever growing power densities of IT equipment can prevent a

29

Flow simulations using particles: bridging computer graphics and CFD  

Science Conference Proceedings (OSTI)

The simulation of the motion of interacting particles is a deceivingly simple, yet powerful and natural method for exploring and animating flows in physical systems as diverse as planetary dark accretion and sea waves, unsteady aerodynamics and nanofluidics.

Petros Koumoutsakos; Georges-Henri Cottet; Diego Rossinelli

2008-08-01T23:59:59.000Z

30

Multiscale and Multiphysic Models in CFD Modeling and Simulation ...  

Science Conference Proceedings (OSTI)

Direct Numerical Simulation of Inclusion Turbulent Deposition at Liquid ... Flow and Shrinkage Pipe Formation on Macrosegregation of Investment Cast -TiAl Alloys ... Numerical Modeling of the Interaction between a Foreign Particle an ...

31

Using CFD Capabilities of CONTAM 3.0 for Simulating Airflow ...  

Science Conference Proceedings (OSTI)

... CFD0 was a CFD program originally developed for ASHRAE research project RP-927 (Chen et al. 1999), and improved by Wang (2007). ...

2010-11-09T23:59:59.000Z

32

CFD simulation of neutral ABL flows Xiaodong Zhang  

E-Print Network (OSTI)

in the atmosphere, prediction of wind load on structure, analysis of wind flow patterns in urban area flow field over different terrains employing Fluent 6.3 software. How accurate the simulation could.2 Problem analysis 18 3.3 User-defined wall functions 18 3.4 Results from different model settings 19 3

33

Air Reverse Circulation Bit Internal Fluid Simulation Based on CFD  

Science Conference Proceedings (OSTI)

The article instructs the work principle of the injector device and its application in the reverse-circulation sampling drilling bit. Then use the fluent fluid engineering emulator software to simulate the internal fluid territory of the injector when ... Keywords: air reverse circulation, bit, injector hole, optimization

Shuqing Hao; Hong-wei Huang; Kun Yin

2009-07-01T23:59:59.000Z

34

Computational simulation of aerosol behaviour.  

E-Print Network (OSTI)

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

Pyykönen, Jouni

2002-01-01T23:59:59.000Z

35

Detailed Simulations of Atmospheric Flow and Dispersion in Downtown Manhattan: An Application of Five Computational Fluid Dynamics Models  

Science Conference Proceedings (OSTI)

Computational fluid dynamics (CFD) model simulations of urban boundary layers have improved in speed and accuracy so that they are useful in assisting in planning emergency response activities related to releases of chemical or biological agents ...

Steven R. Hanna; Michael J. Brown; Fernando E. Camelli; Stevens T. Chan; William J. Coirier; Sura Kim; Olav R. Hansen; Alan H. Huber; R. Michael Reynolds

2006-12-01T23:59:59.000Z

36

Development of CFD-Based Simulation Tools for In-Situ Thermal Processing of Oil Shale/Sands  

Science Conference Proceedings (OSTI)

In our research, we are taking the novel approach of developing and applying high performance computing, computational fluid dynamics (CFD)-based simulation tools to a modified in-situ process for production of oil from oil shale. The simulation tools being developed capture the relevant physical processes and data from a large-scale system. The modified in-situ application is a pilot-scale heat transfer process inside Red Leaf Resourcesâ?? EcoShale capsule. We demonstrate the need to understand fluid flow behavior in the convective channels of the rubblized shale bed as convective heating greatly decreases the time required to heat the oil shale to the production temperature when compared with conductive heating alone. We have developed and implemented a geometry creation strategy for a representative section of the EcoShale capsule, developed a meshing approach to deal with the complicated geometry and produce a well-behaved mesh, analyzed the effects of boundary conditions on the simulation results, and devised a new operator splitting solution algorithm that reduces computational costs by taking advantage of the differing convective and conductive time scales occurring in the simulation. These simulation tools can be applied to a wide range of processes involving convective fluid flow heating in rubblized beds.

None

2012-04-30T23:59:59.000Z

37

COMPUTATIONAL FLUID DYNAMICS MODELING OF SCALED HANFORD DOUBLE SHELL TANK MIXING - CFD MODELING SENSITIVITY STUDY RESULTS  

SciTech Connect

The primary purpose of the tank mixing and sampling demonstration program is to mitigate the technical risks associated with the ability of the Hanford tank farm delivery and celtification systems to measure and deliver a uniformly mixed high-level waste (HLW) feed to the Waste Treatment and Immobilization Plant (WTP) Uniform feed to the WTP is a requirement of 24590-WTP-ICD-MG-01-019, ICD-19 - Interface Control Document for Waste Feed, although the exact definition of uniform is evolving in this context. Computational Fluid Dynamics (CFD) modeling has been used to assist in evaluating scaleup issues, study operational parameters, and predict mixing performance at full-scale.

JACKSON VL

2011-08-31T23:59:59.000Z

38

CFD Simulation of 3D Flow field in a Gas Centrifuge  

SciTech Connect

A CFD method was used to study the whole flow field in a gas centrifuge. In this paper, the VSM (Vector Splitting Method) of the FVM (Finite Volume Method) was used to solve the 3D Navier-Stokes equations. An implicit second-order upwind scheme was adopted. The numerical simulation was successfully performed on a parallel cluster computer and a convergence result was obtained. The simulation shows that: in the withdrawal chamber, a strong detached shock wave is formed in front of the scoop; as the radial position increases, the shock becomes stronger and the distance to scoop front surface is smaller. An oblique shock forms in the clearance between the scoop and the centrifuge wall; behind the shock-wave, the radially-inward motion of gas is induced because of the imbalance of the pressure gradient and the centrifugal force. In the separation chamber, a countercurrent is introduced. This indicates that CFD method can be used to study the complex three-dimensional flow field of gas centrifuges. (authors)

Dongjun Jiang; Shi Zeng [Tsinghua University, Beijing, 100084 (China)

2006-07-01T23:59:59.000Z

39

CFD [computational fluid dynamics] And Safety Factors. Computer modeling of complex processes needs old-fashioned experiments to stay in touch with reality.  

SciTech Connect

Computational fluid dynamics (CFD) is recognized as a powerful engineering tool. That is, CFD has advanced over the years to the point where it can now give us deep insight into the analysis of very complex processes. There is a danger, though, that an engineer can place too much confidence in a simulation. If a user is not careful, it is easy to believe that if you plug in the numbers, the answer comes out, and you are done. This assumption can lead to significant errors. As we discovered in the course of a study on behalf of the Department of Energy's Savannah River Site in South Carolina, CFD models fail to capture some of the large variations inherent in complex processes. These variations, or scatter, in experimental data emerge from physical tests and are inadequately captured or expressed by calculated mean values for a process. This anomaly between experiment and theory can lead to serious errors in engineering analysis and design unless a correction factor, or safety factor, is experimentally validated. For this study, blending times for the mixing of salt solutions in large storage tanks were the process of concern under investigation. This study focused on the blending processes needed to mix salt solutions to ensure homogeneity within waste tanks, where homogeneity is required to control radioactivity levels during subsequent processing. Two of the requirements for this task were to determine the minimum number of submerged, centrifugal pumps required to blend the salt mixtures in a full-scale tank in half a day or less, and to recommend reasonable blending times to achieve nearly homogeneous salt mixtures. A full-scale, low-flow pump with a total discharge flow rate of 500 to 800 gpm was recommended with two opposing 2.27-inch diameter nozzles. To make this recommendation, both experimental and CFD modeling were performed. Lab researchers found that, although CFD provided good estimates of an average blending time, experimental blending times varied significantly from the average.

Leishear, Robert A.; Lee, Si Y.; Poirier, Michael R.; Steeper, Timothy J.; Ervin, Robert C.; Giddings, Billy J.; Stefanko, David B.; Harp, Keith D.; Fowley, Mark D.; Van Pelt, William B.

2012-10-07T23:59:59.000Z

40

OMAE2009-79052 CFD SIMULATION OF WAVE RUN-UP ON A SEMI-SUBMERSIBLE AND COMPARISON WITH EXPERIMENT  

E-Print Network (OSTI)

Use of CFD tools for industrial offshore applications is a common practice nowadays. So is the need for validation of such tools against experimental results. This paper presents one of the CFD tools, ComFLOW, which solves Navier-Stokes equations and employs an improved Volume of Fluid (iVOF) method to find temporary location of fluid’s free surface. The code is used to simulate flow around a semi-submersible offshore platform due to an incoming regular wave. In particular, wave run-up on the semi’s columns and under-deck fluid impact phenomena are investigated on high-accuracy computational grids with number of cells being in range of 10 millions. Results of numerical simulations are compared with experimental data and focus is on local fluid flow details in immediate vicinity of the platform. Wave run-up on the platform’s columns

Bogdan Iwanowski; Marc Lefranc; Rik Wemmenhove

2009-01-01T23:59:59.000Z

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


41

A Coupled CFD-Thermodynamic-Kinetic Model to Simulate a Gas ...  

Science Conference Proceedings (OSTI)

For this purpose, argon gas stirring is commonly used. ... Modeling of Solidification Benchmark of Sn-3% Pb Wt. Alloy under Natural Convection ... CFD Model for Prediction of Liquid Steel Temperature in Ladle during Steel Making and Casting.

42

Hydrogen Sulfide Dispersion Consequences Analysis in Different Wind Speeds: A CFD Based Approach  

Science Conference Proceedings (OSTI)

Hydrogen sulfide (h2s) leakage and dispersion from a sulfide recycle installation in different wind speeds are simulated by implementing a 3D Computational Fluid Dynamics (CFD) model. H2s concentrations of monitor points which represent dispersion contours ... Keywords: CFD, hydrogen Sulfide, dispersion, concenquences analysis, different wind speeds

Bo Zhang; Guo-ming Chen

2009-10-01T23:59:59.000Z

43

CFD Simulation of the CANDU-6 Moderator Circulation Under Normal Operating Conditions  

Science Conference Proceedings (OSTI)

A steady-state 3D simulation for predicting the local subcooling of the moderator in the vicinity of the calandria tubes in a CANDU-6 reactor is performed. For the current simulation, a set of grid structures with the same geometry as the CANDU-6 moderator tank, called 'calandria vessel', is generated and the momentum, heat and continuity equations are solved by CFX-4.3, a CFD code developed by AEA technology. The standard k-{epsilon} turbulence model associated with logarithmic wall treatment is used to model turbulence generation and dissipation within the vessel. The moderator fluid is heavy water. Buoyancy forces are modeled using the Boussinesq approximation in which density is assumed to be a linear function of temperature. The matrix of the calandria tubes in the center region of the calandria vessel is simplified by the porous media approach. The anisotropic hydraulic impedance of the calandria tubes is modeled using the frictional pressure drop correlations suggested by Idelchik and Szymanski. The heat load in this steady-state simulation is conservatively set as 103 MW of 103% full power, consisting of 96.7 MW to the core region and 6.3 MW to the reflector region. The total volumetric flow rate through eight inlet nozzles is 940 L/s and the outlet temperature is constantly 71.0 deg. C. The thermal boundary condition of the circumferential vessel wall is assumed a little heat flux out. As a result, the velocity field and temperature distribution of a CANDU-6 moderator in the operating condition are presented. The flow pattern identified in this simulation is the weak jet momentum-dominated flow, which is generated by the interaction between the buoyancy force by heating and the dominant momentum forces by inlet jets. The calculated maximum temperature of the moderator is 83.0 deg. C at the lower center region of the core, which corresponds to the minimum subcooling of 33.0 deg. C considering the boiling point increase due to the hydrostatic pressure change. (authors)

Bo Wook Rhee; Churl Yoon; Byung-Joo Min [Korea Atomic Energy Research Institute, 150, Dukjin-Dong, Yusong-Gu, Taejon 305-353 (Korea, Republic of)

2002-07-01T23:59:59.000Z

44

Original paper: Validation of CFD simulation for ammonia emissions from an aqueous solution  

Science Conference Proceedings (OSTI)

In order to model and predict ammonia emissions from animal houses, it is important to determine the concentration on the emission surface correctly. In the current literature, Henry's law is usually used to model the mass transfer through the gas-liquid ... Keywords: Ammonia emission, CFD, Concentration boundary condition, Henry's law constant, Vapor-liquid equilibrium

Li Rong; Basman Elhadidi; H. Ezzat Khalifa; Peter V. Nielsen; Guoqiang Zhang

2011-02-01T23:59:59.000Z

45

Dynamic Infrared Simulation.  

E-Print Network (OSTI)

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

Dehlin, Jonas

2006-01-01T23:59:59.000Z

46

AVESTAR® - Gasification Dynamic Simulator  

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

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

47

Fluctuations in molecular dynamics simulations  

Science Conference Proceedings (OSTI)

Statistical fluctuations of a system about its equilibrium state, monitored in a molecular dynamics simulation, are an effective means of computing the thermodynamic and kinetic properties of interfaces in metals and alloys. In this work, three applications ... Keywords: Fluctuations, Grain boundaries, Interfaces, Interfacial free energy, Mobility, Molecular dynamics

J. J. Hoyt; Z. T. Trautt; M. Upmanyu

2010-03-01T23:59:59.000Z

48

A Molecular Dynamics Simulation  

Science Conference Proceedings (OSTI)

Ab Initio Local Energy and Local Stress Calculations: Applications to Materials ... Computational Fluid Dynamics and Experimental Results for the Horizontal .... Films and Applications to a New Generation of Multifunctional Devices/Systems.

49

Simulation of Containment Atmosphere Mixing and Stratification Experiment in the ThAI Facility with a CFD Code  

SciTech Connect

The CFD code CFX4.4 was used to simulate an experiment in the ThAI facility, which was designed for investigation of thermal-hydraulic processes during a severe accident inside a Light Water Reactor containment. In the considered experiment, air was initially present in the vessel, and helium and steam were injected during different phases of the experiment at various mass flow rates and at different locations. The main purpose of the proposed work was to assess the capabilities of the CFD code to reproduce the atmosphere structure with a three-dimensional model, coupled with condensation models proposed by the authors. A three-dimensional model of the ThAI vessel for the CFX4.4 code was developed. The flow in the simulation domain was modeled as single-phase. Steam condensation on vessel walls was modeled as a sink of mass and energy using a correlation that was originally developed for an integral approach. A simple model of bulk phase change was also included. Calculated time-dependent variables together with temperature and volume fraction distributions at the end of different experiment phases are compared to experimental results. (authors)

Babic, Miroslav; Kljenak, Ivo; Mavko, Borut [Reactor Engineering Division, Jozef Stefan Institute, Jamova 39, Ljubljana (Slovenia)

2006-07-01T23:59:59.000Z

50

System dynamics simulation of the telecom industry  

E-Print Network (OSTI)

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

Shapira, Gil, 1971-

2004-01-01T23:59:59.000Z

51

CFD simulation for pedestrian wind comfort and wind safety in urban areas: General decision framework and case study for the Eindhoven University campus  

Science Conference Proceedings (OSTI)

Wind comfort and wind safety for pedestrians are important requirements in urban areas. Many city authorities request studies of pedestrian wind comfort and wind safety for new buildings and new urban areas. These studies involve combining statistical ... Keywords: Building aerodynamics, Built environment, Computational fluid dynamics (CFD), Discomfort and danger, Experimental validation, Guidelines, Wind flow

B. Blocken; W. D. Janssen; T. van Hooff

2012-04-01T23:59:59.000Z

52

Office of Fossil EnergyTOPICAL REPORT: DEVELOPMENT OF CFD_BASED SIMULATION TOOLS FOR IN SITU THERMAL PROCESSING OF OIL SHALE/SANDS  

E-Print Network (OSTI)

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. In our research, we are taking the novel approach of developing and applying high performance computing, computational fluid dynamics (CFD)-based simulation tools to a modified in-situ process for production of oil from oil shale. The simulation tools being developed capture the relevant physical processes and data from a large-scale system. The modified in-situ application

Michal Hradisky; Philip J. Smith; Doe Award; No. De-fe

2009-01-01T23:59:59.000Z

53

Radiation in molecular dynamic simulations  

DOE Green Energy (OSTI)

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

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

2008-10-13T23:59:59.000Z

54

A validation process for multi-phase reacting flow CFD code  

DOE Green Energy (OSTI)

Computational fluid dynamic (CFD) code calculates flow properties for the analysis of a flow system. Flow properties are computed based on conservation principles and various phenomenological models. The accuracy of the computed flow properties highly depends on the validity of the models and the degree of numerical convergence. Validation of a CFD code is essential for application of an engineering system. Multiphase reacting flows are common in industrial applications and few CFD code are available. A CFD code was developed for the simulation of multiphase reacting flows. A validation process was also developed for such a CFD code. The validation was performed for several cases. Examples of industrial devices which are multiphase reacting flow systems include catalytic cracking reactors, glass melting furnaces, coal-fired combustors, and diesel engines.

Chang, S. L.; Zhou, C. Q.; Petrick, M.

2000-05-09T23:59:59.000Z

55

CFD Simulation and Analysis of the Combined Evaporative Cooling and Radiant Ceiling Air-conditioning System  

E-Print Network (OSTI)

Due to such disadvantages as large air duct and high energy consumption of the current all- outdoor air evaporative cooling systems used in the dry region of Northwest China, as well as the superiority of the ceiling cooling system in improving thermal comfort and saving energy, a combined system is presented in this paper. It combines an evaporative cooling system with ceiling cooling, in which the evaporative cooling system handles the entire latent load and one part of the sensible loads, and the ceiling cooling system deals with the other part of sensible loads in the air-conditioned zone, so that the condensation on radiant panels and the insufficiency of cooling capacity can be avoided. The cooling water at 18? used in the cooling coils of ceiling cooling system can be ground water, tap water or the cooled water from cooling towers in the summer. This new air-conditioning system and existing all- outdoor air evaporative cooling system are applied to a project in the city of Lanzhou. Energy consumption analysis of the building is carried out using the energy consumption code. Velocity and temperature distribution in the air-conditioned zone is computed using CFD. According to the results, the energy consumption and indoor human thermal comfort of both systems are then compared. It is concluded that the new system occupies less building space, reduces energy consumption, improves indoor human thermal comfort and saves initial investment.

Xiang, H.; Yinming, L.; Junmei, W.

2006-01-01T23:59:59.000Z

56

NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED BUILDING ENERGY AND CFD SIMULATION  

E-Print Network (OSTI)

for the correct prediction of the convective heat. A finer grid resolution in CFD does not always lead to a more conservation equations of flow on these grid cells. As shown in Figure 1(a), CFD calculates convective heat1 NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED

Chen, Qingyan "Yan"

57

A Molecular Dynamics  

Science Conference Proceedings (OSTI)

A Tale of Two States and More: Modeling of New Generation of Lattice Stability from Zero ... Analysis of Nano Fluid Using CFD-A Hybrid Approach for Cooling Purpose ... Molecular Dynamics Simulations of Grain Boundary Free Energy and

58

A Molecular Dynamic Study  

Science Conference Proceedings (OSTI)

A Tale of Two States and More: Modeling of New Generation of Lattice Stability from Zero ... Analysis of Nano Fluid Using CFD-A Hybrid Approach for Cooling Purpose ... Molecular Dynamics Simulations of Grain Boundary Free Energy and

59

Final report. High resolution CFD and modeling for Diesel engine simulation  

DOE Green Energy (OSTI)

This project focused on developing numerical methods for the simulation of large-scale combustion processes. The particular research focused on algorithm development for compressible flows, the development of geometric techniques for dealing with complex geometries, and their application to problems of independent scientific research, for example, the simulation of laser-induced spark ignited mixture.

Berger, Marsha

2002-07-01T23:59:59.000Z

60

Pollutant dispersion in a large indoor space: Part 2 -Computational Fluid Dynamics (CFD) predictions and comparison with ascale model experiment for isothermal flow  

SciTech Connect

This paper reports on an investigation of the adequacy of Computational fluid dynamics (CFD), using a standard Reynolds Averaged Navier Stokes (RANS) model, for predicting dispersion of neutrally buoyant gas in a large indoor space. We used CFD to predict pollutant (dye) concentration profiles in a water filled scale model of an atrium with a continuous pollutant source. Predictions from the RANS formulation are comparable to an ensemble average of independent identical experiments. Model results were compared to pollutant concentration data in a horizontal plane from experiments in a scale model atrium. Predictions were made for steady-state (fully developed) and transient (developing) pollutant concentrations. Agreement between CFD predictions and ensemble averaged experimental measurements is quantified using the ratios of CFD-predicted and experimentally measured dye concentration at a large number of points in the measurement plane. Agreement is considered good if these ratios fall between 0.5 and 2.0 at all points in the plane. The standard k-epsilon two equation turbulence model obtains this level of agreement and predicts pollutant arrival time to the measurement plane within a few seconds. These results suggest that this modeling approach is adequate for predicting isothermal pollutant transport in a large room with simple geometry.

Finlayson, Elizabeth U.; Gadgil, Ashok J.; Thatcher, Tracy L.; Sextro, Richard G.

2002-10-01T23:59:59.000Z

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


61

A Coupled CFD-PBE Approach Applied to the Simulation of the ...  

Science Conference Proceedings (OSTI)

Direct Numerical Simulation of Inclusion Turbulent Deposition at Liquid ... Flow and Shrinkage Pipe Formation on Macrosegregation of Investment Cast -TiAl Alloys ... Numerical Modeling of the Interaction between a Foreign Particle an ...

62

Review: Application of computational fluid dynamics for modeling and designing photobioreactors for microalgae production: A review  

Science Conference Proceedings (OSTI)

The past decade has seen a rapid increase of numerical simulation studies on photobioreactors (PBRs). Developments in computational fluid dynamics (CFD) and the availability of more powerful computers have paved the way for the modeling and designing ... Keywords: Computational fluid dynamics (CFD), Computer simulation, Microalgae, Photobioreactors

J. P. Bitog; I. -B. Lee; C. -G. Lee; K. -S. Kim; H. -S. Hwang; S. -W. Hong; I. -H. Seo; K. -S. Kwon; E. Mostafa

2011-05-01T23:59:59.000Z

63

The Dalles Dam, Columbia River: Spillway Improvement CFD Study  

DOE Green Energy (OSTI)

This report documents development of computational fluid dynamics (CFD) models that were applied to The Dalles spillway for the US Army Corps of Engineers, Portland District. The models have been successfully validated against physical models and prototype data, and are suitable to support biological research and operations management. The CFD models have been proven to provide reliable information in the turbulent high-velocity flow field downstream of the spillway face that is typically difficult to monitor in the prototype. In addition, CFD data provides hydraulic information throughout the solution domain that can be easily extracted from archived simulations for later use if necessary. This project is part of an ongoing program at the Portland District to improve spillway survival conditions for juvenile salmon at The Dalles. Biological data collected at The Dalles spillway have shown that for the original spillway configuration juvenile salmon passage survival is lower than desired. Therefore, the Portland District is seeking to identify operational and/or structural changes that might be implemented to improve fish passage survival. Pacific Northwest National Laboratory (PNNL) went through a sequence of steps to develop a CFD model of The Dalles spillway and tailrace. The first step was to identify a preferred CFD modeling package. In the case of The Dalles spillway, Flow-3D was as selected because of its ability to simulate the turbulent free-surface flows that occur downstream of each spilling bay. The second step in development of The Dalles CFD model was to assemble bathymetric datasets and structural drawings sufficient to describe the dam (powerhouse, non-overflow dam, spillway, fish ladder entrances, etc.) and tailrace. These datasets are documented in this report as are various 3-D graphical representations of The Dalles spillway and tailrace. The performance of the CFD model was then validated for several cases as the third step. The validated model was then applied to address specific SIS design questions. Specifically, the CFD models were used to evaluate flow deflectors, baffle block removal and the effects of spillwalls. The CFD models were also used to evaluate downstream differences at other locations, such as at the Highway 197 bridge piers and Oregon shore islands, due to alterations in spill pattern. CFD model results were analyzed to quantitatively compare impacts of the spillwall that has subsequently been constructed between bays 6 and 7. CFD model results provided detailed information about how the spillwall would impact downstream flow patterns that complemented results from the 1:80 scale physical model. The CFD model was also used to examine relative differences between the juvenile spill pattern used in previous years and the anticipated spill pattern that will be applied once the wall is complete. In addition, the CFD model examined velocity magnitudes over the downstream basalt shelf to investigate potential for erosion under high flow conditions (e.g., 21 kcfs/bay for bays 1 through 6) with the spillwall in place. Several appendices follow the results and discussion sections of this report. These appendices document the large number of CFD simulations that have been performed by PNNL; both spillway improvement study (SIS) related and those performed for related biological tests.

Cook, Chris B.; Richmond, Marshall C.; Serkowski, John A.

2006-06-01T23:59:59.000Z

64

Phonostat: Thermostatting phonons in molecular dynamics simulations  

E-Print Network (OSTI)

Thermostat algorithms in a molecular dynamics simulation maintain an average temperature of a system by regulating the atomic velocities rather than the internal degrees of freedom. Herein, we present a “phonostat” algorithm ...

Raghunathan, Rajamani

65

LAMMPS Molecular Dynamics Simulator - TMS  

Science Conference Proceedings (OSTI)

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

66

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

DOE Green Energy (OSTI)

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

Tzanos, C. P. (Nuclear Engineering Division)

2007-05-16T23:59:59.000Z

67

Molecular Dynamics Study of Nucleation during Crystallization  

Science Conference Proceedings (OSTI)

A Tale of Two States and More: Modeling of New Generation of Lattice Stability from Zero ... Analysis of Nano Fluid Using CFD-A Hybrid Approach for Cooling Purpose ... Molecular Dynamics Simulations of Grain Boundary Free Energy and

68

Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Horizontal Window Frames with Internal Cavities  

E-Print Network (OSTI)

the two-dimensional heat transfer through building products.Gustavsen, A. 2001. Heat transfer in window frames withand CFD Simulations of Heat Transfer in Horizontal Window

Gustavsen, Arlid

2008-01-01T23:59:59.000Z

69

Dynamics Simulation in a Wave Environment  

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

Coupled Dynamic Simulation in a Wave Coupled Dynamic Simulation in a Wave Environment (Navatek, AEGIR, and WECs) Marine and Hydrokinetics Instrumentation Workshop 9 July 2012 David Kring, Navatek Ltd. Presentation Overview * Introduction to Navatek * AEGIR brief: resistance, seakeeping, global and local loads a 3D, NURBS-based, high-order, Rankine boundary element method ... from same lab as at MIT as WAMIT and SWAN, with pFFT acceleration coupling with controls, structures, aerodynamics, power take-offs * Some WEC applications at Navatek 2 Honolulu, Hawaii, USA Company Background A "Research Shipyard" based in Honolulu, HI Combining simulation-based design with prototype construction

70

Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD  

DOE Green Energy (OSTI)

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

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

1997-09-01T23:59:59.000Z

71

CFD optimization for GDI spray model tuning and enhancement of engine performance  

Science Conference Proceedings (OSTI)

Coupling a 3D Computational Fluid Dynamics (CFD) tool with a rigorous method of decision making is becoming indispensable in the design process of complex systems, as internal combustion engines. CFD based optimization (CFD-O) is here carried out on ... Keywords: CFD based optimization, Charge stratification, Gasoline direct injection, Multidimensional modelling, Spark ignition engines, Split injection

M. Costa; U. Sorge; L. Allocca

2012-07-01T23:59:59.000Z

72

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines  

Science Conference Proceedings (OSTI)

This paper describes the development and application of high performance computing for the acceleration of tactical missile hypergolic propulsion system development. Computational fluid dynamics (CFD) is employed to model the chemically reacting flow ...

Michael J. Nusca; Michael J. McQuaid

2005-06-01T23:59:59.000Z

73

Coupling of a multizone airflow simulation program with computational fluid dynamics for indoor environmental analysis  

E-Print Network (OSTI)

Current design of building indoor environment comprises macroscopIC approaches, such as CONT AM multizone airflow analysis tool, and microscopic approaches that apply Computational Fluid Dynamics (CFD). Each has certain ...

Gao, Yang, 1974-

2002-01-01T23:59:59.000Z

74

Nuclear Energy CFD Application Management System  

Science Conference Proceedings (OSTI)

In modeling and simulation (M&S), it is virtually impossible to separately evaluate the effectiveness of the model from the data used because the results produced rely heavily on the interaction between the two. Both the data and the simulation are responsible for achieving the ultimate goal of providing defensible research and development (R&D) products and decisions. It is therefore vital that data verification and validation (V&V) activities, along with stringent configuration management, be considered part of the overall M&S accreditation process. In support of these goals is the Nuclear Energy CFD Application Management System (NE-CAMS) for nuclear system design and safety analysis. Working with Bettis Laboratory and Utah State University, a plan of action is being developed by the Idaho National Laboratory (INL) that will address the highest and most immediate needs to track and manage computational fluid dynamics (CFD) models and experimental data in an electronic database. The database will intrinsically incorporate the Nuclear Regulatory Commission (NRC) approved policies and procedures for quality. The quality requirements will be such that the model and data must conform to the quality specifications outlined by the NRC before they can be entered into the database. The primary focus of this database is CFD V&V for nuclear industry needs and will, in practice, serve as the best practice guideline that will accommodate NRC regulations. Such a database, along with a prescriptive methodology for how to utilize it, will provide the NRC with accepted CFD results that could potentially be used for licensing. NE-CAMS will incorporate data V&V as key precursors to the distribution of nuclear systems design and safety data, ensuring that these data are appropriate for use in a particular M&S application. Verification will be conducted to provide a level of confidence that the data selected are the most appropriate for the simulation and are properly prepared, i.e., they are complete, correct and conform to predefined procedures and requirements. Validation will ensure that the data accurately represent the real world activity that is being simulated, ensuring the analytical quality of the data. The level of detail and stringency applied against the data V&V activities will be based on a graded approach principle; the higher the risk, the more rigorous the V&V activities. For the V&V activities to be complete, it will be necessary to scrutinize the physical and statistical properties of the extracted data during the overall process. Regardless of the specific technique or methodology, data V&V will be an important component of NE-CAMS.

Hyung Lee; Kimberlyn C. Mousseau

2001-09-01T23:59:59.000Z

75

CFD Modeling of Splash in Molten Materials Processing Operations  

Science Conference Proceedings (OSTI)

A Coupled CFD-Thermodynamic-Kinetic Model to Simulate a Gas Stirred Ladle ... Exercise on Thermal and Thermosolutal Natural Convection in Liquid Alloys.

76

Dynamic simulation recalls condensate piping event  

Science Conference Proceedings (OSTI)

This article describes how experience gained from simulating and reconstructing a condensate piping event will be used by Consolidated Edison to analyze control system problems. A cooperative effort by Con Edison and the Chemical Engineering Department at Polytechnic University used modular modeling system to investigate the probable cause of a Con Edison condensate piping event. Con Edison commissioned the work to serve as a case study for the more general problem of control systems analysis using dynamic simulation and MMS.

Farrell, R.J.; Reneberg, K.O. (Polytechnic Univ., Brooklyn, NY (United States)); Moy, H.C. (Consolidated Edison Co., New York, NY (United States))

1994-05-01T23:59:59.000Z

77

EXAMINATION OF A PROPOSED VALIDATION DATA SET USING CFD CALCULATIONS  

DOE Green Energy (OSTI)

The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from 450 ºC to perhaps 1000 ºC. While computational fluid dynamics (CFD) has not been used for past safety analysis for nuclear reactors in the U. S., it is being considered for such for future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal and accident operational situations. To this end, experimental data have been obtained in a scaled model of a narrow slice of the lower plenum of a prismatic VHTR. The present article presents new results of CFD examinations of these data to explore potential issues with the geometry, the initial conditions, the flow dynamics and the data needed to fully specify the inlet and boundary conditions; results for several turbulence models are examined. Issues are addressed and recommendations about the data are made.

Richard W. Johnson

2009-08-01T23:59:59.000Z

78

Applied Computation 274: Computational Fluid Dynamics Lecturer: David Knezevic  

E-Print Network (OSTI)

, nuclear reactor modeling and blood flow simulation. With major advances in CFD algorithms and computer: With Applications in Incompressible Fluid Dynamics, Oxford University Press, 2005. A. Ern, J.-L. Guermond, Theory

Chen, Yiling

79

Multi-Phase CFD Modeling of Solid Sorbent Carbon Capture System  

Science Conference Proceedings (OSTI)

Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian-Eulerian and Eulerian-Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capture reactors. The results of the simulations show that the FLUENT® Eulerian-Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian-Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian-Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.

Ryan, Emily M.; DeCroix, David; Breault, Ronald W.; Xu, Wei; Huckaby, E. D.; Saha, Kringan; Darteville, Sebastien; Sun, Xin

2013-07-30T23:59:59.000Z

80

A texture-based framework for improving CFD data visualization in a virtual environment  

Science Conference Proceedings (OSTI)

In the field of computational fluid dynamics (CFD) accurate representations of fluid phenomena can be simulated hut require large amounts of data to represent the flow domain. Most datasets generated from a CFD simulation can be coarse, {approx}10,000 nodes or cells, or very fine with node counts on the order of 1,000,000. A typical dataset solution can also contain multiple solutions for each node, pertaining to various properties of the flow at a particular node. Scalar properties such as density, temperature, pressure, and velocity magnitude are properties that are typically calculated and stored in a dataset solution. Solutions are not limited to just scalar properties. Vector quantities, such as velocity, are also often calculated and stored for a CFD simulation. Accessing all of this data efficiently during runtime is a key problem for visualization in an interactive application. Understanding simulation solutions requires a post-processing tool to convert the data into something more meaningful. Ideally, the application would present an interactive visual representation of the numerical data for any dataset that was simulated while maintaining the accuracy of the calculated solution. Most CFD applications currently sacrifice interactivity for accuracy, yielding highly detailed flow descriptions hut limiting interaction for investigating the field.

Gerrick O'Ron Bivins

2005-05-05T23:59:59.000Z

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


81

A texture-based frameowrk for improving CFD data visualization in a virtual environment  

SciTech Connect

In the field of computational fluid dynamics (CFD) accurate representations of fluid phenomena can be simulated but require large amounts of data to represent the flow domain. Most datasets generated from a CFD simulation can be coarse, {approx} 10,000 nodes or cells, or very fine with node counts on the order of 1,000,000. A typical dataset solution can also contain multiple solutions for each node, pertaining to various properties of the flow at a particular node. Scalar properties such as density, temperature, pressure, and velocity magnitude are properties that are typically calculated and stored in a dataset solution. Solutions are not limited to just scalar properties. Vector quantities, such as velocity, are also often calculated and stored for a CFD simulation. Accessing all of this data efficiently during runtime is a key problem for visualization in an interactive application. Understanding simulation solutions requires a post-processing tool to convert the data into something more meaningful. Ideally, the application would present an interactive visual representation of the numerical data for any dataset that was simulated while maintaining the accuracy of the calculated solution. Most CFD applications currently sacrifice interactivity for accuracy, yielding highly detailed flow descriptions but limiting interaction for investigating the field.

Biveins, Gerrick O'Ron

2005-05-01T23:59:59.000Z

82

CFD calculations of S809 aerodynamic characteristics  

DOE Green Energy (OSTI)

Steady-state, two-dimensional CFD calculations were made for the S809 laminar-flow, wind-turbine airfoil using the commercial code CFD-ACE. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data from the Delft University 1.8 m x 1.25 m low-turbulence wind tunnel. This work highlights two areas in CFD that require further investigation and development in order to enable accurate numerical simulations of flow about current generation wind-turbine airfoils: transition prediction and turbulence modeling. The results show that the laminar-to-turbulent transition point must be modeled correctly to get accurate simulations for attached flow. Calculations also show that the standard turbulence model used in most commercial CFD codes, the k-{epsilon} model, is not appropriate at angles of attack with flow separation.

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

1997-01-01T23:59:59.000Z

83

Dynamic Simulation of a Helium Liquefier  

SciTech Connect

Dynamic behavior of a helium liquefier has been studied in detail with a Cryogenic Process REal-time SimulaTor (C-PREST) at the National Institute for Fusion Science (NIFS). The C-PREST is being developed to integrate large-scale helium cryogenic plant design, operation and maintenance for optimum process establishment. As a first step of simulations of cooldown to 4.5 K with the helium liquefier model is conducted, which provides a plant-process validation platform. The helium liquefier consists of seven heat exchangers, a liquid-nitrogen (LN2) precooler, two expansion turbines and a liquid-helium (LHe) reservoir. Process simulations are fulfilled with sequence programs, which were implemented with C-PREST based on an existing liquefier operation. The interactions of a JT valve, a JT-bypass valve and a reservoir-return valve have been dynamically simulated. The paper discusses various aspects of refrigeration process simulation, including its difficulties such as a balance between complexity of the adopted models and CPU time.

Maekawa, R.; Ooba, K.; Mito, T. [National Institute for Fusion Science, Toki, Gifu, 509-5292 (Japan); Nobutoki, M. [Nippon Sanso Co., Kawasaki, Kanagawa, 210-0861 (Japan)

2004-06-23T23:59:59.000Z

84

Physics results from dynamical overlap fermion simulations  

E-Print Network (OSTI)

I summarize the physics results obtained from large-scale dynamical overlap fermion simulations by the JLQCD and TWQCD collaborations. The numerical simulations are performed at a fixed global topological sector; the physics results in the theta-vacuum is reconstructed by correcting the finite volume effect, for which the measurement of the topological susceptibility is crucial. Physics applications we studied so far include a calculation of chiral condensate, pion mass, decay constant, form factors, as well as (vector and axial-vector) vacuum polarization functions and nucleon sigma term.

Shoji Hashimoto

2008-11-08T23:59:59.000Z

85

IGCC Dynamic Simulator and Training Center  

SciTech Connect

Integrated Gasification Combined Cycle (IGCC) is emerging as the technology of choice for providing clean, low-cost electricity for the next generation of coal-fired power plants and will play a central role in the development of high-efficiency, zero-emissions power plants such as FutureGen. Several major utilities and developers recently announced plans to build IGCC plants and other major utilities are evaluating IGCC’s suitability for base-load capacity additions. This recent surge of attention to IGCC power generation is creating a growing demand for experience with the analysis, operation, and control of commercial-scale IGCC plants. To meet this need, the National Energy Technology Laboratory (NETL) has launched a project to develop a generic, full-scope, IGCC dynamic plant simulator for use in establishing a state-of-the-art simulator training center at West Virginia University’s (WVU) National Research Center for Coal and Energy (NRCCE). The IGCC Dynamic Simulator & Training (DS&T) Center will be established under the auspices of the Collaboratory for Process & Dynamic Systems Modeling (“Collaboratory”) organized between NETL, WVU, the University of Pittsburgh, and Carnegie Mellon University.

Zitney, S.E.; Erbes, M.R. (Enginomix, LLC)

2006-10-01T23:59:59.000Z

86

Computational fluid dynamics modelling of sewage sludge mixing in an anaerobic digester  

Science Conference Proceedings (OSTI)

In this paper, the development of a computational fluid dynamics (CFD) model to simulate the mechanical mixing of sewage sludge at laboratory scale is reported. The paper recommends a strategy for modelling mechanically mixed sewage sludge at laboratory ... Keywords: Biogas, CFD, Digestion, Energy, Non-Newtonian fluid, Sewage sludge, Turbulence

J. Bridgeman

2012-02-01T23:59:59.000Z

87

Computational fluid dynamics simulation of chemical reactors: Application of in situ adaptive tabulation to methane thermochlorination chemistry  

SciTech Connect

Recently, a novel algorithm--in situ adaptive tabulation--has been proposed to effectively incorporate detailed chemistry in computational fluid dynamics (CFD) simulations for turbulent reacting flows. In this work, detailed tests performed on a pairwise-mixing stirred reactor (PMSR) model are presented implementing methane thermochlorination chemistry to validate the in situ adaptive tabulation (ISAT) algorithm. The detailed kinetic scheme involves 3 elements (H, C, Cl) and 38 chemical species undergoing a total of 152 elementary reactions. The various performance issues (error control, accuracy, storage requirements, speed-up) involved in the implementation of detailed chemistry in particle-based methods (full PDF methods) are discussed. Using an error tolerance of {epsilon}{sub tol} = 2 x 10{sup {minus}4}, sufficiently accurate results with minimal storage requirements and significantly less computational time than would be required with direct integration are obtained. Based on numerous test simulations, an error tolerance in the range of 10{sup {minus}3}--10{sup {minus}4} is found to be satisfactory for carrying out full PDF simulations of methane thermochlorination reactors. The results presented here demonstrate that the implementation of ISAT makes possible the hitherto formidable task of implementing detailed chemistry in CFD simulations of methane thermochlorination reactors.

Shah, J.J.; Fox, R.O.

1999-11-01T23:59:59.000Z

88

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

DOE Green Energy (OSTI)

The Very High Temperature gas cooled reactor (VHTR) is one of the GEN IV reactor concepts that have been proposed for thermochemical hydrogen production and other process-heat applications like coal gasification. The USDOE has selected the VHTR for further research and development, aiming to demonstrate emissions-free electricity and hydrogen production at a future time. One of the major safety advantages of the VHTR is the potential for passive decay heat removal by natural circulation of air in a Reactor Cavity Cooling System (RCCS). The air-side of the RCCS is very similar to the Reactor Vessel Auxiliary Cooling System (RVACS) that has been proposed for the PRISM reactor design. The design and safety analysis of the RVACS have been based on extensive analytical and experimental work performed at ANL. The Natural Convective Shutdown Heat Removal Test Facility (NSTF) at ANL that simulates at full scale the air-side of the RVACS was built to provide experimental support for the design and analysis of the PRISM RVACS system. The objective of this work is to demonstrate that the NSTF facility can be used to generate RCCS experimental data: to validate CFD and systems codes for the analysis of the RCCS; and to support the design and safety analysis of the RCCS.

Tzanos, C. P.; Nuclear Engineering Division

2007-05-16T23:59:59.000Z

89

SDI CFD MODELING ANALYSIS  

SciTech Connect

The Savannah River Remediation (SRR) Organization requested that Savannah River National Laboratory (SRNL) develop a Computational Fluid Dynamics (CFD) method to mix and blend the miscible contents of the blend tanks to ensure the contents are properly blended before they are transferred from the blend tank; such as, Tank 50H, to the Salt Waste Processing Facility (SWPF) feed tank. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. The transient CFD governing equations consisting of three momentum equations, one mass balance, two turbulence transport equations for kinetic energy and dissipation rate, and one species transport were solved by an iterative technique until the species concentrations of tank fluid were in equilibrium. The steady-state flow solutions for the entire tank fluid were used for flow pattern analysis, for velocity scaling analysis, and the initial conditions for transient blending calculations. A series of the modeling calculations were performed to estimate the blending times for various jet flow conditions, and to investigate the impact of the cooling coils on the blending time of the tank contents. The modeling results were benchmarked against the pilot scale test results. All of the flow and mixing models were performed with the nozzles installed at the mid-elevation, and parallel to the tank wall. From the CFD modeling calculations, the main results are summarized as follows: (1) The benchmark analyses for the CFD flow velocity and blending models demonstrate their consistency with Engineering Development Laboratory (EDL) and literature test results in terms of local velocity measurements and experimental observations. Thus, an application of the established criterion to SRS full scale tank will provide a better, physically-based estimate of the required mixing time, and elevation of transfer pump for minimum sludge disturbance. (2) An empirical equation for a tank with no cooling coils agrees reasonably with the current modeling results for the dual jet. (3) From the sensitivity study of the cooling coils, it was found that the tank mixing time for the coiled tank was about two times longer than that of the tank fluid with no coils under the 1/10th scale, while the coiled tank required only 50% longer than the one without coils under the full scale Tank 50H. In addition, the time difference is reduced when the pumping U{sub o}d{sub o} value is increased for a given tank. (4) The blending time for T-shape dual jet pump is about 20% longer than that of 15{sup o} upward V-shape pump under the 1/10th pilot-scale tank, while the time difference between the two pumps is about 12% for the full-scale Tank 50H. These results are consistent with the literature information. (5) A transfer pump with a solid-plate suction screen operating at 130 gpm can be located 9.5 inches above settled sludge for 2 in screen height in a 85 ft waste tank without disturbing any sludge. Detailed results are summarized in Table 13. Final pump performance calculations were made by using the established CW pump design, and operating conditions to satisfy the two requirements of minimum sludge disturbance, and adequate blending of tank contents. The final calculation results show that the blending times for the coiled and uncoiled tanks coupled with the CW pump design are 159 and 83 minutes, respectively. All the results are provided in Table 16.

Lee, S.

2011-05-05T23:59:59.000Z

90

Applications of Grid techniques in the CFD field  

E-Print Network (OSTI)

up fundermental CFD study in fluid dynamics, for example, mechanism of turbulence. (2) Grid resources 1 can also be used to solve large numbers of small tasks. By modifying one or some parameters like Mach number, angle of attach, iteration steps, CFD... Server MyProxy Server Computing Resources Cambridge CFD Web Portal (CamCFDWP) Fig. 6 Architecture of Cambridge CFD Web Por- tal (CamCFDWP) A successful login window shown in Fig.7. Once the 5 user logs in, it is time for him to submit jobs to remote...

Yang, Xiaobo; Hayes, Mark

2008-06-26T23:59:59.000Z

91

CFD modeling of entrained-flow coal gasifiers with improved physical and chemical sub-models  

Science Conference Proceedings (OSTI)

Optimization of an advanced coal-fired integrated gasification combined cycle system requires an accurate numerical prediction of gasifier performance. While the turbulent multiphase reacting flow inside entrained-flow gasifiers has been modeled through computational fluid dynamic (CFD), the accuracy of sub-models requires further improvement. Built upon a previously developed CFD model for entrained-flow gasification, the advanced physical and chemical sub-models presented here include a moisture vaporization model with consideration of high mass transfer rate, a coal devolatilization model with more species to represent coal volatiles and heating rate effect on volatile yield, and careful selection of global gas phase reaction kinetics. The enhanced CFD model is applied to simulate two typical oxygen-blown entrained-flow configurations including a single-stage down-fired gasifier and a two-stage up-fired gasifier. The CFD results are reasonable in terms of predicted carbon conversion, syngas exit temperature, and syngas exit composition. The predicted profiles of velocity, temperature, and species mole fractions inside the entrained-flow gasifier models show trends similar to those observed in a diffusion-type flame. The predicted distributions of mole fractions of major species inside both gasifiers can be explained by the heterogeneous combustion and gasification reactions and the homogeneous gas phase reactions. It was also found that the syngas compositions at the CFD model exits are not in chemical equilibrium, indicating the kinetics for both heterogeneous and gas phase homogeneous reactions are important. Overall, the results achieved here indicate that the gasifier models reported in this paper are reliable and accurate enough to be incorporated into process/CFD co-simulations of IGCC power plants for systemwide design and optimization.

Ma, J.; Zitney, S.

2012-01-01T23:59:59.000Z

92

Molecular dynamics simulations of ordered alkane chains physisorbed on graphite  

E-Print Network (OSTI)

Molecular dynamics simulations of ordered alkane chains physisorbed on graphite Reinhard Hentschke molecular axes oriented parallel to the substrate. Here we employ molecular dynamics (MD) simulations to obtain more details on the molecular order and dynamics within the alkane lamellae as a function

Peters, Achim

93

Computational fluid dynamics simulation of the air/suppressant flow in an uncluttered F18 engine nacelle  

DOE Green Energy (OSTI)

For the purposes of designing improved Halon-alternative fire suppression strategies for aircraft applications, Computational Fluid Dynamics (CFD) simulations of the air flow, suppressant transport, and air-suppressant mixing within an uncluttered F18 engine nacelle were performed. The release of inert gases from a Solid Propellant Gas Generator (SPGG) was analyzed at two different injection locations in order to understand the effect of injection position on the flow patterns and the mixing of air and suppression agent. An uncluttered engine nacelle was simulated to provide insight into the global flow features as well as to promote comparisons with previous nacelle fire tests and recent water tunnel tests which included little or no clutter. Oxygen concentration levels, fuel/air residence times that would exist if a small fuel leak were present, velocity contours, and streamline patterns are presented inside the engine nacelle. The numerical results show the influence of the gent release location on regions of potential flame extinction due to oxygen inerting and high flame strain. The occurrence of inflow through the exhaust ducts on the aft end of the nacelle is also predicted. As expected, the predicted oxygen concentration levels were consistently higher than the measured levels since a fire was not modeled in this analysis. Despite differences in the conditions of these simulations and the experiments, good agreement was obtained between the CFD predictions and the experimental measurements.

Lopez, A.R.; Gritzo, L.A.; Hassan, B.

1997-06-01T23:59:59.000Z

94

Molecular dynamics simulation of Li surface erosion and bubble formation  

E-Print Network (OSTI)

Molecular dynamics simulation of Li surface erosion and bubble formation Z. Insepov *, A. Hassanein Structure and dynamical properties of liquid Li containing He atoms were studied by the Molecular Dynamics devices. Molecular dynamics (MD) method is capable of studying important collision processes and providing

Harilal, S. S.

95

Molecular Dynamics Simulations of Microscale Fluid Transport  

E-Print Network (OSTI)

Recent advances in micro-science and technology, like Micro-ElectroMechanical Systems (MEMS), have generated a group of unique liquid flow problems that involve characteristic length scales of a micron. Also, in manufacturing processes such as coatings, current continuum models are unable to predict microscale physical phenomena that appear in these nonequilibrium systems. It is suspected that in these systems, molecular-level processes can control the interfacial energy and viscoelastic properties at the liquid/solid boundary. A massively parallel molecular dynamics (MD) code has been developed to better understand microscale transport mechanisms, fluid-structure interactions, and scale effects in micro-domains. Specifically, this MD code has been used to analyze liquid channel flow problems for a variety of channel widths, e.g. 0.005-0.05 microns. This report presents results from MD simulations of Poiseuille flow and Couette flow problems and address both scaling and modeling issues...

C. C. Wong; A. R. Lopez; M.J. Stevens; S. J. Plimpton; Category Uc; Like Micro-electro

1998-01-01T23:59:59.000Z

96

Kinetic Simulations of Fusion Energy Dynamics at the Extreme...  

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

Kinetic Simulations of Fusion Energy Dynamics at the Extreme Scale PI Name: William Tang PI Email: tang@pppl.gov Institution: Princeton Plasma Physics Laboratory Allocation...

97

Computational Fluid Dynamic Simulations of a Regenerative Process...  

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

Fluid Dynamic Simulations of a Regenerative Process for Carbon Dioxide Capture in Advanced Gasification Based Power Systems Background The Department of Energy (DOE) National...

98

Dynamic Simulation of Cell Voltage Resonance Effect in Aluminum ...  

Science Conference Proceedings (OSTI)

Dubal Cell Voltage Drop Initiatives towards Low Energy High Amperage Cells · Dynamic Simulation of Cell Voltage Resonance Effect in Aluminum Electrolysis ...

99

Two-Dimensional Computational Fluid Dynamics and Conduction Simulation...  

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

Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Horizontal Window Frames with Internal Cavities Title Two-Dimensional Computational...

100

Molecular Statics and Molecular Dynamics Simulations of the ...  

Science Conference Proceedings (OSTI)

Presentation Title, Molecular Statics and Molecular Dynamics Simulations of the Critical Stress for Motion of a/3 Screw Dislocations in a-Ti at Low ...

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


101

Molecular Dynamics Simulation of Cavitation in Metallic Glass  

Science Conference Proceedings (OSTI)

We have undertaken a series of molecular dynamics simulations of cavitation under hydrostatic tension in a binary metallic glass analog using pair-wise ...

102

Avestar® - Integrated Gasification Combined Cycle (IGCC) Dynamic Simulator  

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

Integrated Gasification Combined Cycle (IGCC) Dynamic Simulator Integrated Gasification Combined Cycle (IGCC) Dynamic Simulator The AVESTAR® center offers courses using the Integrated Gasification Combined Cycle (IGCC) Dynamic Simulator. The IGCC simulator builds on and reaches beyond existing combined-cycle and conventional-coal power plant simulators to combine--for the first time--a Gasification with CO2 Capture process simulator with a Combined-Cycle power simulator together in a single dynamic simulation framework. The AVESTAR® center IGCC courses provide unique, comprehensive training on all aspects of an IGCC plant, illustrating the high-efficiency aspects of the gasifier, gas turbine, and steam turbine integration. IGCC Operator training station HMI display for overview of IGCC Plant - Train A Reference:

103

CFD MODELING OF ITER CABLE-IN-CONDUIT SUPERCONDUCTORS. PART V: COMBINED MOMENTUM AND HEAT TRANSFER IN RIB ROUGHENED PIPES  

Science Conference Proceedings (OSTI)

Computational Fluid Dynamics (CFD) techniques have been proposed and applied in a series of papers to analyze cable-in-conduit conductors (CICC) for the International Thermonuclear Experimental Reactor (ITER). Previous work on the pressure drop in the central channel of ITER CICC is extended here to the problem of combined heat and momentum transfer. The CFD model, solved by the FLUENT commercial code, is first validated against 2D and 3D data from compact heat exchangers, showing good agreement. The Colburn analogy between the friction factor f and the Nusselt number Nu is not verified in the considered 2D geometries, as shown by both experiment and simulation. The validated CFD model is finally applied to the 3D analysis of central channel-like geometries relevant for ITER CICC. It is shown that the heat transfer coefficient on the central channel side stays relatively close to the smooth-pipe (Dittus-Boelter) value.

Zanino, R.; Giors, S. [Dipartimento di Energetica, Politecnico Torino, I-10129 (Italy)

2008-03-16T23:59:59.000Z

104

Software Framework for Advanced Power Plant Simulations  

SciTech Connect

This report summarizes the work accomplished during the Phase II development effort of the Advanced Process Engineering Co-Simulator (APECS). The objective of the project is to develop the tools to efficiently combine high-fidelity computational fluid dynamics (CFD) models with process modeling software. During the course of the project, a robust integration controller was developed that can be used in any CAPE-OPEN compliant process modeling environment. The controller mediates the exchange of information between the process modeling software and the CFD software. Several approaches to reducing the time disparity between CFD simulations and process modeling have been investigated and implemented. These include enabling the CFD models to be run on a remote cluster and enabling multiple CFD models to be run simultaneously. Furthermore, computationally fast reduced-order models (ROMs) have been developed that can be 'trained' using the results from CFD simulations and then used directly within flowsheets. Unit operation models (both CFD and ROMs) can be uploaded to a model database and shared between multiple users.

John Widmann; Sorin Munteanu; Aseem Jain; Pankaj Gupta; Mark Moales; Erik Ferguson; Lewis Collins; David Sloan; Woodrow Fiveland; Yi-dong Lang; Larry Biegler; Michael Locke; Simon Lingard; Jay Yun

2010-08-01T23:59:59.000Z

105

Bonneville Project: CFD of the Spillway Tailrace  

SciTech Connect

US Army Corps of Engineers, Portland District (CENWP) operates the Bonneville Lock and Dam Project on the Columbia River. High spill flows that occurred during 2011 moved a large volume of rock from downstream of the spillway apron to the stilling basin and apron. Although 400 cubic yards of rocks were removed from the stilling basin, there are still large volumes of rock downstream of the apron that could, under certain flow conditions, move upstream into the stilling basin. CENWP is investigating operational changes that could be implemented to minimize future movement of rock into the stilling basin. A key analysis tool to develop these operational changes is a computational fluid dynamics (CFD) model of the spillway. A free-surface CFD model of the Bonneville spillway tailrace was developed and applied for four flow scenarios. These scenarios looked at the impact of flow volume and flow distribution on tailrace hydraulics. The simulation results showed that areas of upstream flow existed near the river bed downstream of the apron, on the apron, and within the stilling basin for all flows. For spill flows of 300 kcfs, the cross-stream and downstream extent of the recirculation zones along Cascade and Bradford Island was very dependent on the spill pattern. The center-loaded pattern had much larger recirculation zones than the flat or bi-modal pattern. The lower flow (200 kcfs) with a flat pattern had a very large recirculation zone that extended half way across the channel near the river bed. A single flow scenario (300 kcfs of flow in a relatively flat spill pattern) was further interrogated using Lagrangian particle tracking. The tracked particles (with size and mass) showed the upstream movement of sediments onto the concrete apron and against the vertical wall between the apron and the stilling basin from seed locations downstream of the apron and on the apron.

Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.; Romero Gomez, Pedro DJ

2012-11-19T23:59:59.000Z

106

Numerical simulation of cloud droplet formation in a tank  

Science Conference Proceedings (OSTI)

Using the computational fluid dynamics (CFD) code FLUENT 6 together with the fine particle model (FPM), numerical simulations of droplet dynamics in a 12.4m^3 cloud tank were conducted. The coupled fields of water vapor, temperature, flow velocity, particle ... Keywords: Cloud droplet formation, Particle-dynamics modeling, Stirred tank, Turbulence

Matthias Schütze; Frank Stratmann

2008-09-01T23:59:59.000Z

107

Molecular dynamics simulations and drug discovery  

E-Print Network (OSTI)

JE: On the determination of molecular fields. II. From thescalability for parallel molecular dynamics. J Comput PhysKale L, Schulten K: Scalable molecular dynamics with NAMD. J

Durrant, Jacob D; McCammon, J Andrew

2011-01-01T23:59:59.000Z

108

Exploiting hierarchical parallelisms for molecular dynamics simulation on multicore clusters  

Science Conference Proceedings (OSTI)

We have developed a scalable hierarchical parallelization scheme for molecular dynamics (MD) simulation on multicore clusters. The scheme explores multilevel parallelism combining: (1) Internode parallelism using spatial decomposition via message passing; ... Keywords: Molecular dynamics simulation, Multicore cluster, Scalable hierarchical parallelization scheme, Single instruction multiple data

Liu Peng; Manaschai Kunaseth; Hikmet Dursun; Ken-Ichi Nomura; Weiqiang Wang; Rajiv K. Kalia; Aiichiro Nakano; Priya Vashishta

2011-07-01T23:59:59.000Z

109

Anton, a special-purpose machine for molecular dynamics simulation  

Science Conference Proceedings (OSTI)

The ability to perform long, accurate molecular dynamics (MD) simulations involving proteins and other biological macro-molecules could in principle provide answers to some of the most important currently outstanding questions in the fields of biology, ... Keywords: bioinformatics, biomolecular system simulation, computational biology, computational drug design, molecular dynamics, protein folding, protein structure, special-purpose machine

David E. Shaw; Martin M. Deneroff; Ron O. Dror; Jeffrey S. Kuskin; Richard H. Larson; John K. Salmon; Cliff Young; Brannon Batson; Kevin J. Bowers; Jack C. Chao; Michael P. Eastwood; Joseph Gagliardo; J. P. Grossman; C. Richard Ho; Douglas J. Ierardi; István Kolossváry; John L. Klepeis; Timothy Layman; Christine McLeavey; Mark A. Moraes; Rolf Mueller; Edward C. Priest; Yibing Shan; Jochen Spengler; Michael Theobald; Brian Towles; Stanley C. Wang

2007-06-01T23:59:59.000Z

110

Design of an Enterprise Dynamic Performance Simulation and Analysis System  

Science Conference Proceedings (OSTI)

Many problems in enterprise running faced by managers can be resolved by simulation of the corresponding system dynamics model. It is often desirable to forecasting enterprise running in the next period. And managers hope to find the reason quickly if ... Keywords: dynamic performance, simulation, sensitivity, diagnose, performance optimization

Zheng Li; Yueting Chai; Yi Liu

2011-04-01T23:59:59.000Z

111

TANK48 CFD MODELING ANALYSIS  

SciTech Connect

The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitative mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions as the single-phase model. The modeling results show that the flow patterns driven by four pump operation satisfy the solid suspension requirement, and the average solid concentration at the plane of the transfer pump inlet is about 12% higher than the tank average concentrations for the 70 inch tank level and about the same as the tank average value for the 29 inch liquid level. When one of the four pumps is not operated, the flow patterns are satisfied with the minimum suspension velocity criterion. However, the solid concentration near the tank bottom is increased by about 30%, although the average solid concentrations near the transfer pump inlet have about the same value as the four-pump baseline results. The flow pattern results show that although the two-pump case satisfies the minimum velocity requirement to suspend the sludge particles, it provides the marginal mixing results for the heavier or larger insoluble materials such as MST and KTPB particles. The results demonstrated that when more than one jet are aiming at the same position of the mixing tank domain, inefficient flow patterns are provided due to the highly localized momentum dissipation, resulting in inactive suspension zone. Thus, after completion of the indexed solids suspension, pump rotations are recommended to avoid producing the nonuniform flow patterns. It is noted that when tank liquid level is reduced from the highest level of 70 inches to the minimum level of 29 inches for a given number of operating pumps, the solid mixing efficiency becomes better since the ratio of the pump power to the mixing volume becomes larger. These results are consistent with the literature results.

Lee, S.

2011-05-17T23:59:59.000Z

112

AVESTAR® - Natural Gas Combined Cycle (NGCC) Dynamic Simulator  

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

Natural Gas Combined Cycle (NGCC) Dynamic Simulator Natural Gas Combined Cycle (NGCC) Dynamic Simulator A simulator that can provide future engineers with realistic, hands-on experience for operating advanced natural gas combined cycle (NGCC) power plants will soon be available at an innovative U.S. Department of Energy training center. Under a new cooperative research and development agreement signed by the Office of Fossil Energy's National Energy Technology Laboratory (NETL) and Invensys Operations Management, the partners will develop, test, and deploy a dynamic simulator and operator training system (OTS) for a generic NGCC power plant equipped for use with post-combustion carbon capture. NETL will operate the new dynamic simulator/OTS at the AVESTAR (Advanced Virtual Energy Simulation Training and Research) Center in Morgantown, W.Va.

113

Petascale, Adaptive CFD | Argonne Leadership Computing Facility  

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

Petascale, Adaptive CFD Petascale, Adaptive CFD Petascale, Adaptive CFD PI Name: Kenneth Jansen PI Email: jansenke@colorado.edu Institution: U. Colorado-Boulder Allocation Program: ESP Allocation Hours at ALCF: 150 Million Year: 2010 to 2013 Research Domain: Engineering The aerodynamic simulations proposed will involve modeling of active flow control based on synthetic jet actuation that has been shown experimentally to produce large-scale flow changes (e.g., re-attachment of separated flow or virtual aerodynamic shaping of lifting surfaces) from micro-scale input (e.g., a 0.1 W piezoelectric disk resonating in a cavity alternately pushes/pulls out/in the fluid through a small slit to create small-scale vortical structures that interact with, and thereby dramatically alter, the cross flow). This is a process that has yet to be understood fundamentally.

114

The use of dynamic adaptive chemistry in combustion simulation of gasoline surrogate fuels  

Science Conference Proceedings (OSTI)

A computationally efficient dynamic adaptive chemistry (DAC) scheme is described that permits on-the-fly mechanism reduction during reactive flow calculations. The scheme reduces a globally valid full mechanism to a locally, instantaneously applicable smaller mechanism. Previously we demonstrated its applicability to homogeneous charge compression ignition (HCCI) problems with n-heptane [L. Liang, J.G. Stevens, J.T. Farrell, Proc. Combust. Inst. 32 (2009) 527-534]. In this work we demonstrate the broader utility of the DAC scheme through the simulation of HCCI and shock tube ignition delay times (IDT) for three gasoline surrogates, including two- and three-component blends of primary reference fuels (PRF) and toluene reference fuels (TRF). Both a detailed 1099-species mechanism and a skeletal 150-species mechanism are investigated as the full mechanism to explore the impact of fuel complexity on the DAC scheme. For all conditions studied, pressure and key species profiles calculated using the DAC scheme are in excellent agreement with the results obtained using the full mechanisms. For the HCCI calculations using the 1099- and 150-species mechanisms, the DAC scheme achieves 70- and 15-fold CPU time reductions, respectively. For the IDT problems, corresponding speed-up factors of 10 and two are obtained. Practical guidance is provided for choosing the search-initiating species set, selecting the threshold, and implementing the DAC scheme in a computational fluid dynamics (CFD) framework. (author)

Liang, Long; Raman, Sumathy; Farrell, John T. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Stevens, John G. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Department of Mathematical Sciences, Montclair State University, Montclair, NJ 07043 (United States)

2009-07-15T23:59:59.000Z

115

Simulation of chemical reaction dynamics on an NMR quantum computer  

E-Print Network (OSTI)

Quantum simulation can beat current classical computers with minimally a few tens of qubits and will likely become the first practical use of a quantum computer. One promising application of quantum simulation is to attack challenging quantum chemistry problems. Here we report an experimental demonstration that a small nuclear-magnetic-resonance (NMR) quantum computer is already able to simulate the dynamics of a prototype chemical reaction. The experimental results agree well with classical simulations. We conclude that the quantum simulation of chemical reaction dynamics not computable on current classical computers is feasible in the near future.

Dawei Lu; Nanyang Xu; Ruixue Xu; Hongwei Chen; Jiangbin Gong; Xinhua Peng; Jiangfeng Du

2011-05-21T23:59:59.000Z

116

Molecular Dynamics Simulations of Thermoset Polymers for ...  

Science Conference Proceedings (OSTI)

Materials Genomics Past & Future: From CALPHAD to Flight · Modelling the Properties of Multi-Component Commercial Alloys · Molecular Dynamics ...

117

Molecular Dynamics Simulations of Grain Boundary Free Energy ...  

Science Conference Proceedings (OSTI)

A Tale of Two States and More: Modeling of New Generation of Lattice Stability ... Analysis of Nano Fluid Using CFD-A Hybrid Approach for Cooling Purpose.

118

Computer Simulations of Protein Dynamics and Thermodynamics  

Science Conference Proceedings (OSTI)

The computational challenges of producing realistic biomedical simulations are reviewed. Techniques for applying classical mechanics simulation methods to proteins and ways to solve Newton's equations are discussed. Two recent applications of these methods ...

David Case

1993-10-01T23:59:59.000Z

119

Avestar® - Syngas-Fired Combined Cycle Dynamic Simulator  

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

Syngas-Fired Combined Cycle Dynamic Simulator Syngas-Fired Combined Cycle Dynamic Simulator The AVESTAR® center offers courses using the Combined Cycle Simulator, focusing on the power generation process after gasification. This simulator is well-suited for concentrated training on operation and control of the gas and steam turbines; condensate, feed water, and circulating water systems; heat recovery steam generator; and selective catalytic reduction (SCR) unit. Combined cycle simulator startup operations include bringing up the gas turbine to rated speed on natural gas and then switching over to the firing of synthesis gas. Key capabilities of the Combined Cycle Simulator include: Combined Cycle Simulator Operator training station HMI display for overview of Gas Turbine - Train A Normal base load operation

120

Millisecond-scale molecular dynamics simulations on Anton  

Science Conference Proceedings (OSTI)

Anton is a recently completed special-purpose supercomputer designed for molecular dynamics (MD) simulations of biomolecular systems. The machine's specialized hardware dramatically increases the speed of MD calculations, making possible for the first ...

David E. Shaw; Ron O. Dror; John K. Salmon; J. P. Grossman; Kenneth M. Mackenzie; Joseph A. Bank; Cliff Young; Martin M. Deneroff; Brannon Batson; Kevin J. Bowers; Edmond Chow; Michael P. Eastwood; Douglas J. Ierardi; John L. Klepeis; Jeffrey S. Kuskin; Richard H. Larson; Kresten Lindorff-Larsen; Paul Maragakis; Mark A. Moraes; Stefano Piana; Yibing Shan; Brian Towles

2009-11-01T23:59:59.000Z

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


121

Anton, a special-purpose machine for molecular dynamics simulation  

Science Conference Proceedings (OSTI)

The ability to perform long, accurate molecular dynamics (MD) simulations involving proteins and other biological macro-molecules could in principle provide answers to some of the most important currently outstanding questions in the fields of biology, ...

David E. Shaw; Martin M. Deneroff; Ron O. Dror; Jeffrey S. Kuskin; Richard H. Larson; John K. Salmon; Cliff Young; Brannon Batson; Kevin J. Bowers; Jack C. Chao; Michael P. Eastwood; Joseph Gagliardo; J. P. Grossman; C. Richard Ho; Douglas J. Ierardi; István Kolossváry; John L. Klepeis; Timothy Layman; Christine McLeavey; Mark A. Moraes; Rolf Mueller; Edward C. Priest; Yibing Shan; Jochen Spengler; Michael Theobald; Brian Towles; Stanley C. Wang

2008-07-01T23:59:59.000Z

122

Physics issues in simulations with dynamical overlap fermions  

E-Print Network (OSTI)

We discuss the impact of various improvements on simulations of dynamical overlap fermions using the Hybrid Monte Carlo algorithm. We focus on the usage of fat links and multiple pseudo-fermion fields.

Thomas DeGrand; Stefan Schaefer

2004-12-01T23:59:59.000Z

123

Simulated Convective Lines with Leading Precipitation. Part I: Governing Dynamics  

Science Conference Proceedings (OSTI)

This article, the first of two describing a study in which the authors used idealized numerical simulations to investigate convective lines with leading precipitation, addresses the dynamics governing the systems' structures and individual air ...

Matthew D. Parker; Richard H. Johnson

2004-07-01T23:59:59.000Z

124

Dynamical Effects of Aerosol Perturbations on Simulated Idealized Squall Lines  

Science Conference Proceedings (OSTI)

The dynamical effects of increased aerosol loading on the strength and structure of numerically simulated squall lines are explored. Results are explained in the context of RKW theory. Changes in aerosol loading lead to changes in rain drop size ...

Zachary J. Lebo; Hugh Morrison

125

Simulation of the dynamic response of a damped taught string  

E-Print Network (OSTI)

Marine pipeline are facing new issues involved by the increase of the depth of exploited oil and gas reservoirs. This thesis discusses the changes in the dynamic behavior of marine pipelines and proposes a simple simulation ...

Favennec, Hervé

2007-01-01T23:59:59.000Z

126

Scaling studies and conceptual experiment designs for NGNP CFD assessment  

SciTech Connect

The objective of this report is to document scaling studies and conceptual designs for flow and heat transfer experiments intended to assess CFD codes and their turbulence models proposed for application to prismatic NGNP concepts. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. Two aspects of the complex flow in an NGNP are being addressed: (1) flow and thermal mixing in the lower plenum ("hot streaking" issue) and (2) turbulence and resulting temperature distributions in reactor cooling channels ("hot channel" issue). Current prismatic NGNP concepts are being examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses have been applied to determine key non-dimensional parameters and their magnitudes over this operating range. For normal operation, the flow in the coolant channels can be considered to be dominant turbulent forced convection with slight transverse property variation. In a pressurized cooldown (LOFA) simulation, the flow quickly becomes laminar with some possible buoyancy influences. The flow in the lower plenum can locally be considered to be a situation of multiple hot jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentumdominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other. Two types of heat transfer experiments are being considered. One addresses the "hot channel" problem, if necessary. The second type will treat heated jets entering a model plenum. Unheated MIR (Matched-Index-of-Refraction) experiments are first steps when the geometry is complicated. One does not want to use a computational technique which will not even handle constant properties properly. The purpose of the fluid dynamics experiments is to develop benchmark databases for the assessment of CFD solutions of the momentum equations, scalar mixing and turbulence models for typical NGNP plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. As indicated by the scaling studies, in normal full power operation of a typical NGNP conceptual design, buoyancy influences should be negligible in the lower plenum. The MIR experiment will simulate flow features of the paths of jets as they mix in flowing through the array of posts in a lower plenum en route to the single exit duct. Conceptual designs for such experiments are described.

D. M. McEligot; G. E. McCreery

2004-11-01T23:59:59.000Z

127

Large-Scale Hybrid Dynamic Simulation Employing Field Measurements  

Science Conference Proceedings (OSTI)

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

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

2004-06-30T23:59:59.000Z

128

Better HMC integrators for dynamical simulations  

SciTech Connect

We show how to improve the molecular dynamics step of Hybrid Monte Carlo, both by tuning the integrator using Poisson brackets measurements and by the use of force gradient integrators. We present results for moderate lattice sizes.

M.A. Clark, Balint Joo, A.D. Kennedy, P.J. Silva

2010-06-01T23:59:59.000Z

129

Dynamic electrothermal simulation of integrated resistors at device level  

Science Conference Proceedings (OSTI)

This paper presents the dynamic electrothermal simulation of a rectangular resistor integrated on a semi-conductor substrate. Due to the temperature dependence of the electrical conductivity of the resistive sheet, self-heating provokes a coupling between ... Keywords: Electrothermal simulation, Nonlinearity, Structure functions, Thermal impedance, Transient

B. Vermeersch; G. De Mey

2009-09-01T23:59:59.000Z

130

Phase-field Simulations/Molecular Dynamics  

Science Conference Proceedings (OSTI)

The sharp interface model was used to determine the SLI free energy and its anisotropy by fitting to the MD data. Finally, the MD simulation of the B2 growth ...

131

Programmable quantum simulation by dynamic Hamiltonian engineering  

E-Print Network (OSTI)

Quantum simulation is a promising near term application for mesoscale quantum information processors, with the potential to solve computationally intractable problems at the scale of just a few dozen interacting quantum systems. Recent experiments in a range of technical platforms have demonstrated the basic functionality of quantum simulation applied to quantum magnetism, quantum phase transitions, and relativistic quantum mechanics. In all cases, the underlying hardware platforms restrict the achievable inter-particle interaction, forming a serious constraint on the ability to realize a versatile, programmable, quantum simulator. In this work, we address this problem by developing novel sequences of unitary operations that engineer desired effective Hamiltonians in the time-domain. The result is a hybrid programmable analog simulator permitting a broad class of interacting spin-lattice models to be generated starting only with an arbitrary native inter-particle interaction and single-qubit addressing. Building on previous work proving that universal simulation is possible using both entangling gates and single-qubit unitaries, we show how determining the relevant hardware "program" of unitary pulses to implement an arbitrary spin Hamiltonian on such a simulator can be formulated as a linear program that runs in polynomial time and scales efficiently in hardware resources. Our analysis extends from circuit model quantum information to adiabatic quantum evolutions, where our approach allows for the creation of non-native ground state solutions to a computation.

David L. Hayes; Steven T. Flammia; Michael J. Biercuk

2013-09-26T23:59:59.000Z

132

Processes and Procedures for Application of CFD to Nuclear Reactor Safety Analysis  

SciTech Connect

Traditionally, nuclear reactor safety analysis has been performed using systems analysis codes such as RELAP5, which was developed at the INL. However, goals established by the Generation IV program, especially the desire to increase efficiency, has lead to an increase in operating temperatures for the reactors. This increase pushes reactor materials to operate towards their upper temperature limits relative to structural integrity. Because there will be some finite variation of the power density in the reactor core, there will be a potential for local hot spots to occur in the reactor vessel. Hence, it has become apparent that detailed analysis will be required to ensure that local ‘hot spots’ do not exceed safety limits. It is generally accepted that computational fluid dynamics (CFD) codes are intrinsically capable of simulating fluid dynamics and heat transport locally because they are based on ‘first principles.’ Indeed, CFD analysis has reached a fairly mature level of development, including the commercial level. However, CFD experts are aware that even though commercial codes are capable of simulating local fluid and thermal physics, great care must be taken in their application to avoid errors caused by such things as inappropriate grid meshing, low-order discretization schemes, lack of iterative convergence and inaccurate time-stepping. Just as important is the choice of a turbulence model for turbulent flow simulation. Turbulence models model the effects of turbulent transport of mass, momentum and energy, but are not necessarily applicable for wide ranges of flow types. Therefore, there is a well-recognized need to establish practices and procedures for the proper application of CFD to simulate flow physics accurately and establish the level of uncertainty of such computations. The present document represents contributions of CFD experts on what the basic practices, procedures and guidelines should be to aid CFD analysts to obtain accurate estimates of the flow and energy transport as applied to nuclear reactor safety. However, it is expected that these practices and procedures will require updating from time to time as research and development affect them or replace them with better procedures. The practices and procedures are categorized into five groups. These are: 1.Code Verification 2.Code and Calculation Documentation 3.Reduction of Numerical Error 4.Quantification of Numerical Uncertainty (Calculation Verification) 5.Calculation Validation. These five categories have been identified from procedures currently required of CFD simulations such as those required for publication of a paper in the ASME Journal of Fluids Engineering and from the literature such as Roache [1998]. Code verification refers to the demonstration that the equations of fluid and energy transport have been correctly coded in the CFD code. Code and calculation documentation simply means that the equations and their discretizations, etc., and boundary and initial conditions used to pose the fluid flow problem are fully described in available documentation. Reduction of numerical error refers to practices and procedures to lower numerical errors to negligible or very low levels as is reasonably possible (such as avoiding use of first-order discretizations). The quantification of numerical uncertainty is also known as calculation verification. This means that estimates are made of numerical error to allow the characterization of the numerical

Richard W. Johnson; Richard R. Schultz; Patrick J. Roache; Ismail B. Celik; William D. Pointer; Yassin A. Hassan

2006-09-01T23:59:59.000Z

133

Simulating the dynamics of auroral phenomena  

Science Conference Proceedings (OSTI)

Simulating natural phenomena has always been a focal point for computer graphics research. Its importance goes beyond the production of appealing presentations, since research in this area can contribute to the scientific understanding of complex natural ... Keywords: Atmospheric effects, natural phenomena, plasma phenomena, rendering

Gladimir V. G. Baranoski; Justin Wan; Jon G. Rokne; Ian Bell

2005-01-01T23:59:59.000Z

134

Ensemble Simulations with Coupled Atmospheric Dynamic and Dispersion Models: Illustrating Uncertainties in Dosage Simulations  

Science Conference Proceedings (OSTI)

Ensemble simulations made using a coupled atmospheric dynamic model and a probabilistic Lagrangian puff dispersion model were employed in a forensic analysis of the transport and dispersion of a toxic gas that may have been released near Al ...

Thomas T. Warner; Rong-Shyang Sheu; James F. Bowers; R. Ian Sykes; Gregory C. Dodd; Douglas S. Henn

2002-05-01T23:59:59.000Z

135

CFD modeling of commercial-scale entrained-flow coal gasifiers  

SciTech Connect

Optimization of an advanced coal-fired integrated gasification combined cycle system requires an accurate numerical prediction of gasifier performance. Computational fluid dynamics (CFD) has been used to model the turbulent multiphase reacting flow inside commercial-scale entrained-flow coal gasifiers. Due to the complexity of the physical and chemical processes involved, the accuracy of sub-models requires further improvement. Built upon a previously developed CFD model for entrained-flow gasification, the advanced physical and chemical sub-models presented in this paper include a moisture vaporization model with consideration of high mass transfer rate and a coal devolatilization model with more species to represent coal volatiles and the heating rate effect on volatile yield. The global gas phase reaction kinetics is also carefully selected. To predict a reasonable peak temperature of the coal/O{sub 2} flame inside an entrained-flow gasifier, the reserve reaction of H{sub 2} oxidation is included in the gas phase reaction model. The enhanced CFD model is applied to simulate two typical commercial-scale oxygen-blown entrained-flow configurations including a single-stage down-fired gasifier and a two-stage up-fired gasifier. The CFD results are reasonable in terms of predicted carbon conversion, syngas exit temperature, and syngas exit composition. The predicted profiles of velocity, temperature, and species mole fractions inside the entrained-flow gasifier models show trends similar to those observed in a diffusion-type flame. The predicted distributions of mole fractions of major species inside both gasifiers can be explained by the heterogeneous combustion and gasification reactions and the homogeneous gas phase reactions. It was also found that the syngas compositions at the CFD model exits are not in chemical equilibrium, indicating the kinetics for both heterogeneous and gas phase homogeneous reactions are important. Overall, the results achieved here indicate that the gasifier models reported in this paper are reliable and accurate enough to be incorporated into process/CFD co-simulations of IGCC power plants for system-wide design and optimization.

Ma, J.; Zitney, S.

2012-01-01T23:59:59.000Z

136

Modeling and simulation of consumer response to dynamic pricing.  

Science Conference Proceedings (OSTI)

Assessing the impacts of dynamic-pricing under the smart grid concept is becoming extremely important for deciding its full deployment. In this paper, we develop a model that represents the response of consumers to dynamic pricing. In the model, consumers use forecasted day-ahead prices to shift daily energy consumption from hours when the price is expected to be high to hours when the price is expected to be low while maintaining the total energy consumption as unchanged. We integrate the consumer response model into the Electricity Market Complex Adaptive System (EMCAS). EMCAS is an agent-based model that simulates restructured electricity markets. We explore the impacts of dynamic-pricing on price spikes, peak demand, consumer energy bills, power supplier profits, and congestion costs. A simulation of an 11-node test network that includes eight generation companies and five aggregated consumers is performed for a period of 1 month. In addition, we simulate the Korean power system.

Valenzuela, J.; Thimmapuram, P.; Kim, J (Decision and Information Sciences); (Auburn Univ.)

2012-08-01T23:59:59.000Z

137

Lessons Learned From Dynamic Simulations of Advanced Fuel Cycles  

SciTech Connect

Years of performing dynamic simulations of advanced nuclear fuel cycle options provide insights into how they could work and how one might transition from the current once-through fuel cycle. This paper summarizes those insights from the context of the 2005 objectives and goals of the Advanced Fuel Cycle Initiative (AFCI). Our intent is not to compare options, assess options versus those objectives and goals, nor recommend changes to those objectives and goals. Rather, we organize what we have learned from dynamic simulations in the context of the AFCI objectives for waste management, proliferation resistance, uranium utilization, and economics. Thus, we do not merely describe “lessons learned” from dynamic simulations but attempt to answer the “so what” question by using this context. The analyses have been performed using the Verifiable Fuel Cycle Simulation of Nuclear Fuel Cycle Dynamics (VISION). We observe that the 2005 objectives and goals do not address many of the inherently dynamic discriminators among advanced fuel cycle options and transitions thereof.

Steven J. Piet; Brent W. Dixon; Jacob J. Jacobson; Gretchen E. Matthern; David E. Shropshire

2009-04-01T23:59:59.000Z

138

LINAC BEAM DYNAMICS SIMULATIONS WITH PY-ORBIT  

Science Conference Proceedings (OSTI)

Linac dynamics simulation capabilities of the PyORBIT code are discussed. PyORBIT is an open source code and a further development of the original ORBIT code that was created and used for design, studies, and commissioning of the SNS ring. The PyORBIT code, like the original one, has a two-layer structure. C++ is used to perform time-consuming computations, and the program flow is controlled from a Python language shell. The flexible structure makes it possible to use PyORBIT also for linac dynamics simulations. A benchmark of PyORBIT with Parmila and the XAL Online model is presented.

Shishlo, Andrei P [ORNL

2012-01-01T23:59:59.000Z

139

A fully dynamical simulation of central nuclear collisions  

E-Print Network (OSTI)

We present a fully dynamical simulation of central nuclear collisions around mid-rapidity at LHC energies. Unlike previous treatments, we simulate all phases of the collision, including the equilibration of the system. For the simulation, we use numerical relativity solutions to AdS/CFT for the pre-equilibrium stage, viscous hydrodynamics for the plasma equilibrium stage and kinetic theory for the low density hadronic stage. Our pre-equilibrium stage provides initial conditions for hydrodynamics and our results are insensitive to the AdS/hydro switching time. The resulting light particle spectra reproduce the measurements from the ALICE experiment at all transverse momenta.

van der Schee, Wilke; Pratt, Scott

2013-01-01T23:59:59.000Z

140

Formal Calibration Methodology for CFD Model Development to Support the Operation of Energy Efficient Buildings  

E-Print Network (OSTI)

Computational Fluid Dynamics (CFD) is a robust tool for modeling interactions within and between fluids and solids. CFD can help understand and predict phenomena that are difficult to test experimentally leading to cleaner, healthier, and better controlled internal environments. In this research a CFD model of the internal environment of an office space will be developed. The CFD model will then be calibrated using real data taken from a well-positioned wireless sensor network and weather station. The work focuses on developing systematically calibrated CFD models for controlled environments that include clean rooms, health environments, pharmaceutical storage rooms and information and communication technology locations, utilizing wireless sensor networks. The calibrated CFD model will be used to optimize the positions of the physical sensors for the control of energy efficient internal environments by building operators. This could result in significant energy and economic savings and lead to more accurately controlled internal environments.

Hajdukiewicz, M.; Keane, M.; O'Flynn, B.; O'Grady, W.

2010-01-01T23:59:59.000Z

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


141

Molecular Dynamics Simulations on High-Performance Reconfigurable Computing Systems  

Science Conference Proceedings (OSTI)

The acceleration of molecular dynamics (MD) simulations using high-performance reconfigurable computing (HPRC) has been much studied. Given the intense competition from multicore and GPUs, there is now a question whether MD on HPRC can be competitive. ... Keywords: FPGA-based coprocessors, application acceleration, bioinformatics, biological sequence alignment, high performance reconfigurable computing

Matt Chiu; Martin C. Herbordt

2010-11-01T23:59:59.000Z

142

Simulation of Dynamic Characteristic for Passive Hydraulic Mount  

Science Conference Proceedings (OSTI)

Dynamic modeling of Passive Hydraulic Engine Mounts (PHEM) is developed with inertia track, decoupler and throttle. Mathematically, the state equations governing vibration isolation behaviors of the PHEMs are presented and solved by means of the lumped ... Keywords: passive hydraulic mount, simulation, test

Zhang Yunxia; Fang Zuhua

2009-08-01T23:59:59.000Z

143

Dynamic Simulation of DFIG Wind Turbines on FPGA Boards  

E-Print Network (OSTI)

Dynamic Simulation of DFIG Wind Turbines on FPGA Boards Hao Chen, Student Member, IEEE, Song Sun is a friction coefficient. The wind turbine model is based on the relation between the upstream wind speed V w + 1 where p is the air density; Rw is the wind turbine radius; cp (A, (3) is the performance

Zambreno, Joseph A.

144

Molecular Dynamics Simulation of Macromolecules Using Graphics Processing Unit  

E-Print Network (OSTI)

Molecular dynamics (MD) simulation is a powerful computational tool to study the behavior of macromolecular systems. But many simulations of this field are limited in spatial or temporal scale by the available computational resource. In recent years, graphics processing unit (GPU) provides unprecedented computational power for scientific applications. Many MD algorithms suit with the multithread nature of GPU. In this paper, MD algorithms for macromolecular systems that run entirely on GPU are presented. Compared to the MD simulation with free software GROMACS on a single CPU core, our codes achieve about 10 times speed-up on a single GPU. For validation, we have performed MD simulations of polymer crystallization on GPU, and the results observed perfectly agree with computations on CPU. Therefore, our single GPU codes have already provided an inexpensive alternative for macromolecular simulations on traditional CPU clusters and they can also be used as a basis to develop parallel GPU programs to further speedup the computations.

Ji Xu; Ying Ren; Wei Ge; Xiang Yu; Xiaozhen Yang; Jinghai Li

2010-01-21T23:59:59.000Z

145

DOE/NETL IGCC Dynamic Simulator Research and Training Center  

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

NETL IGCC Dynamic Simulator NETL IGCC Dynamic Simulator Research and Training Center 01 Aug 2008 Volume 2: IGCC Process Descriptions DOE/NETL-2008/1324 NETL Collaboratory for Process & Dynamic Systems Research Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement,

146

Wind flow modeling and simulation over the Giza Plateau cultural heritage site in Egypt  

Science Conference Proceedings (OSTI)

In this article, the wind flow over one of the most important Egyptian historical heritage sites, the Giza Plateau, was investigated using the Computational Fluid Dynamics (CFD) state-of-the-art techniques. The present study addresses the influences ... Keywords: Cultural heritage, Giza Plateau, Great Sphinx, computational fluid dynamics, wind modeling and simulation, wind over heritage sites

Ashraf S. Hussein; Hisham El-Shishiny

2009-11-01T23:59:59.000Z

147

Complete CFD analysis of a Velocity XL-5 RG with flight-test verification  

E-Print Network (OSTI)

The Texas A&M Flight Research Laboratory (FRL) recently received delivery of its newest aircraft, the Velocity XL-5 RG. The Velocity can fly faster than the other aircraft owned by the FRL and does not have a propeller in the front of the aircraft to disrupt the air flow. These are definite advantages that make the Velocity an attractive addition to the FRL inventory to be used in boundary-layer stability and transition control. Possible mounting locations built into the aircraft for future projects include hard points in the wings and roof of the fuselage. One of the drawbacks of the aircraft is that it has a canard ahead of the main wing that could disrupt the incoming flow for a wing glove or research requiring test pieces mounted to the hard point in the wing. Therefore, it is necessary to understand the influence the canard and the impact of its wake on the wing of the aircraft before any in-depth aerodynamic research could be completed on the aircraft. A combination of in-flight measurements of the canard wake and Computational Fluid Dynamics (CFD) were used to provide a clear picture of the flowfield around the aircraft. The first step of the project consisted of making a 3-D CAD model of the aircraft. This model was then used for the CFD simulations in Fluent. 2-D, 3-D, inviscid, and viscous simulations were preformed on the aircraft. A pressure rake was designed to house a 5-hole probe and 18 Pitot probes that extended forward of the main wing to measure the location and strength of the canard wake at various flight conditions. There were five primary test points that were recorded at multiple times over the course of three flights. Once all of the data were collected from the flights, the freestream conditions became the inputs into the final, 3-D CFD simulations on the aircraft. The good agreement between the CFD results and the in-flight measurements provided the necessary verification of the CFD model of the aircraft. These results can be used in the future planning and execution of experiments involving the Velocity XL-5 RG.

Schouten, Shane Michael

2008-05-01T23:59:59.000Z

148

Development and Verification of a Computational Fluid Dynamics Model of a Horizontal-Axis Tidal Current Turbine  

DOE Green Energy (OSTI)

This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.

Lawson, M. J.; Li, Y.; Sale, D. C.

2011-10-01T23:59:59.000Z

149

Structural dynamics test simulation and optimization for aerospace components  

SciTech Connect

This paper initially describes an innovative approach to product realization called Knowledge Based Testing (KBT). This research program integrates test simulation and optimization software, rapid fabrication techniques and computational model validation to support a new experimentally-based design concept. This design concept implements well defined tests earlier in the design cycle enabling the realization of highly reliable aerospace components. A test simulation and optimization software environment provides engineers with an essential tool needed to support this KBT approach. This software environment, called the Virtual Environment for Test Optimization (VETO), integrates analysis and test based models to support optimal structural dynamic test design. A goal in developing this software tool is to provide test and analysis engineers with a capability of mathematically simulating the complete structural dynamics test environment within a computer. A developed computational model of an aerospace component can be combined with analytical and/or experimentally derived models of typical structural dynamic test instrumentation within the VETO to determine an optimal test design. The VETO provides the user with a unique analysis and visualization environment to evaluate new and existing test methods in addition to simulating specific experiments designed to maximize test based information needed to validate computational models. The results of both a modal and a vibration test design are presented for a reentry vehicle and a space truss structure.

Klenke, S.E.; Baca, T.J.

1996-06-01T23:59:59.000Z

150

Climate Simulations with an Isentropic Finite Volume Dynamical Core  

SciTech Connect

This paper discusses the impact of changing the vertical coordinate from a hybrid pressure to a hybrid-isentropic coordinate within the finite volume dynamical core of the Community Atmosphere Model (CAM). Results from a 20-year climate simulation using the new model coordinate configuration are compared to control simulations produced by the Eulerian spectral and FV dynamical cores of CAM which both use a pressure-based ({sigma}-p) coordinate. The same physical parameterization package is employed in all three dynamical cores. The isentropic modeling framework significantly alters the simulated climatology and has several desirable features. The revised model produces a better representation of heat transport processes in the atmosphere leading to much improved atmospheric temperatures. We show that the isentropic model is very effective in reducing the long standing cold temperature bias in the upper troposphere and lower stratosphere, a deficiency shared among most climate models. The warmer upper troposphere and stratosphere seen in the isentropic model reduces the global coverage of high clouds which is in better agreement with observations. The isentropic model also shows improvements in the simulated wintertime mean sea-level pressure field in the northern hemisphere.

Chen, Chih-Chieh; Rasch, Philip J.

2012-04-15T23:59:59.000Z

151

A Quasi-Dynamic HVAC and Building Simulation Methodology  

E-Print Network (OSTI)

This thesis introduces a quasi-dynamic building simulation methodology which complements existing building simulators by allowing transient models of HVAC (heating, ventilating and air-conditioning) systems to be created in an analogous way to their design and simulated in a computationally efficient manner. The methodology represents a system as interconnected, object-oriented sub-models known as components. Fluids and their local properties are modeled using discrete, incompressible objects known as packets. System wide pressure and flow rates are modeled similar to electrical circuit models. Transferring packets between components emulates fluid flow, while the system wide fluid circuit formed by the components' interconnections determines system wide pressures and flow rates. A tool named PAQS, after the PAacketized Quasi-dynamic Simulation methodology, was built to demonstrate the described methodology. Validation tests of PAQS found that its steady state energy use predictions differed less than 3% from a comparable steady state model. PAQS was also able to correctly model the transient behavior of a dynamic linear analytical system.

Davis, Clinton Paul

2012-05-01T23:59:59.000Z

152

Ad Hoc Distributed Dynamic Data-Driven Simulations of Surface Transportation Systems  

Science Conference Proceedings (OSTI)

An ad hoc distributed dynamic data-driven simulation is a collection of autonomous online simulations brought together to model an operational system. They offer the potential of increased accuracy, responsiveness, and robustness compared to centralized ... Keywords: ad hoc distributed simulation, dynamic data-driven application system, microscopic simulation model, online simulation

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

2009-04-01T23:59:59.000Z

153

Prototyping Bio-Nanorobots using Molecular Dynamics Simulation  

E-Print Network (OSTI)

This paper presents a molecular mechanics study using a molecular dynamics software (NAMD) coupled to virtual reality (VR) techniques for intuitive Bio-NanoRobotic prototyping. Using simulated Bio-Nano environments in VR, the operator can design and characterize through physical simulation and 3-D visualization the behavior of Bio-NanoRobotic components and structures. The main novelty of the proposed simulations is based on the characterization of stiffness performances of passive joints-based deca-alanine protein molecule and active joints-based viral protein motor (VPL) in their native environment. Their use as elementary Bio-NanoRobotic components (1 dof platform) are also simulated and the results discussed.

Hamdi, Mustapha; Ferreira, A; Mavroidis, Constantinos

2007-01-01T23:59:59.000Z

154

Advanced beam-dynamics simulation tools for RIA.  

Science Conference Proceedings (OSTI)

We are developing multi-particle beam-dynamics simulation codes for RIA driver-linac simulations extending from the low-energy beam transport (LEBT) line to the end of the linac. These codes run on the NERSC parallel supercomputing platforms at LBNL, which allow us to run simulations with large numbers of macroparticles. The codes have the physics capabilities needed for RIA, including transport and acceleration of multiple-charge-state beams, beam-line elements such as high-voltage platforms within the linac, interdigital accelerating structures, charge-stripper foils, and capabilities for handling the effects of machine errors and other off-normal conditions. This year will mark the end of our project. In this paper we present the status of the work, describe some recent additions to the codes, and show some preliminary simulation results.

Garnett, R. W.; Wangler, T. P.; Billen, J. H.; Qiang, J.; Ryne, R.; Crandall, K. R.; Ostroumov, P.; York, R.; Zhao, Q.; Physics; LANL; LBNL; Tech Source; Michigan State Univ.

2005-01-01T23:59:59.000Z

155

Bibliography for Verification and Validation in Computational Simulations  

Science Conference Proceedings (OSTI)

A bibliography has been compiled dealing with the verification and validation of computational simulations. The references listed in this bibliography are concentrated in the field of computational fluid dynamics (CFD). However, references from the following fields are also included: operations research, heat transfer, solid dynamics, software quality assurance, software accreditation, military systems, and nuclear reactor safety. This bibliography, containing 221 references, is not meant to be comprehensive. It was compiled during the last ten years in response to the author's interest and research in the methodology for verification and validation. The emphasis in the bibliography is in the following areas: philosophy of science underpinnings, development of terminology and methodology, high accuracy solutions for CFD verification, experimental datasets for CFD validation, and the statistical quantification of model validation. This bibliography should provide a starting point for individual researchers in many fields of computational simulation in science and engineering.

Oberkampf, W.L.

1998-10-01T23:59:59.000Z

156

The molecular dynamics simulation of ion-induced ripple growth  

Science Conference Proceedings (OSTI)

The wavelength-dependence of ion-sputtering induced growth of repetitive nanostructures, such as ripples has been studied by molecular dynamics (MD) simulations in Si. The early stage of the ion erosion driven development of ripples has been simulated on prepatterned Si stripes with a wavy surface. The time evolution of the height function and amplitude of the sinusoidal surface profile has been followed by simulated ion-sputtering. According to Bradley-Harper (BH) theory, we expect correlation between the wavelength of ripples and the stability of them. However, we find that in the small ripple wavelength ({lambda}) regime BH theory fails to reproduce the results obtained by molecular dynamics. We find that at short wavelengths ({lambda}35 nm is stabilized in accordance with the available experimental results. According to the simulations, few hundreds of ion impacts in {lambda} long and few nanometers wide Si ripples are sufficient for reaching saturation in surface growth for for {lambda}>35 nm ripples. In another words, ripples in the long wavelength limit seems to be stable against ion-sputtering. A qualitative comparison of our simulation results with recent experimental data on nanopatterning under irradiation is attempted.

Suele, P. [Research Institute for Technical Physics and Materials Science, Konkoly Thege u. 29-33, 1125 Budapest (Hungary); Heinig, K.-H. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 51 01 19, 01314 Dresden (Germany)

2009-11-28T23:59:59.000Z

157

GTRF Calculations Using Hydra-TH (L3 Milestone THM.CFD.P5.05)  

SciTech Connect

This report describes the work carried out for completion of the Thermal Hydraulics Methods (THM) Level 3 Milestone THM.CFD.P5.05 for the Consortium for Advanced Simulation of Light Water Reactors (CASL). A series of body-fitted computational meshes have been generated by Numeca's Hexpress/Hybrid, a.k.a. 'Spider', meshing technology for the V5H 3 x 3 and 5 x 5 rod bundle geometries and subsequently used to compute the fluid dynamics of grid-to-rod fretting (GTRF). Spider is easy to use, fast, and automatically generates high-quality meshes for extremely complex geometries, required for the GTRF problem. Hydra-TH has been used to carry out large-eddy simulations on both 3 x 3 and 5 x 5 geometries, using different mesh resolutions. The results analyzed show good agreement with Star-CCM+ simulations and experimental data.

Bakosi, Jozsef [Los Alamos National Laboratory; Christon, Mark A. [Los Alamos National Laboratory; Francois, Marianne M. [Los Alamos National Laboratory; Lowrie, Robert B. [Los Alamos National Laboratory; Nourgaliev, Robert [Los Alamos National Laboratory

2012-09-05T23:59:59.000Z

158

Simulating Soil Carbon Dynamics, Erosion and Tillage with EPIC  

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

Simulating Soil Carbon Dynamics, Erosion Simulating Soil Carbon Dynamics, Erosion and Tillage with EPIC 1 R. C. Izaurralde (cesar.izaurralde@pnl.gov; 202-646-5227) Joint Global Change Research Institute (JGCRI) Pacific Northwest Nat'l Lab. - Univ. of Maryland 901 D St. S.W., Suite 900 Washington, DC 20024-2115 J. R. Williams (williams@brc.tamus.edu; 254-774-6124) Texas A&M University Blackland Research Center 808 East Blackland Road Temple, TX 76502 W. B. McGill (mcgill@unbc.ca) Faculty of Science and Management University of Northern British Columbia 3333 University Way, Prince George, BC V2N 4Z9 N. J. Rosenberg (nj.rosenberg@pnl.gov; 202-646-5029) Joint Global Change Research Institute (JGCRI) Pacific Northwest Nat'l Lab. - Univ. of Maryland 901 D St. S.W., Suite 900 Washington, DC 20024-2115

159

AVESTAR® - Oxy-Coal Carbon Capture (OCCC) Dynamic Simulator  

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

Oxy-Coal Carbon Capture (OCCC) Dynamic Simulator Oxy-Coal Carbon Capture (OCCC) Dynamic Simulator FutureGen 2.0 is a first-of-its-kind, near-zero emissions coal-fueled power plant using oxy-combustion technology to capture the plant's carbon emissions. To help meet the Nation's ever growing demand for clean energy, the FutureGen Industrial Alliance (Alliance) was formed to test and commercialize advanced coal-based systems fully integrated with carbon capture and geologic storage technologies. In cooperation with the U.S. Department of Energy (DOE), the Alliance and its project partners AirLiquide and Babcock & Wilcox, will upgrade an existing power plant in Meredosia, Illinois with oxy-coal carbon capture (OCCC) technology to capture and permanantly store approximately 1.0 million tonnes of CO2 each year.

160

Molecular dynamics simulation of displacement cascades in FeCr alloys  

E-Print Network (OSTI)

Molecular dynamics simulation of displacement cascades in Fe­Cr alloys L. Malerba a,*, D. Terentyev by displacement cascades in the relevant material. Molecular dynamics (MD) is well known to be the simulation tool

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161

Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine  

E-Print Network (OSTI)

A nanoscale-sized Stirling engine with an atomistic working fluid has been modeled using molecular dynamics simulation. The design includes heat exchangers based on thermostats, pistons attached to a flywheel under load, and a regenerator. Key aspects of the behavior, including the time-dependent flows, are described. The model is shown to be capable of stable operation while producing net work at a moderate level of efficiency.

Rapaport, D C

2009-01-01T23:59:59.000Z

162

Dynamic Simulation and Training for IGCC Power Plants  

SciTech Connect

Integrated Gasification Combined Cycle (IGCC) is emerging as the technology of choice for providing clean, low-cost electricity for the next generation of coal-fired power plants and will play a central role in the development of high-efficiency, zero-emissions power plants such as FutureGen. Several major utilities and developers recently announced plans to build IGCC plants and other major utilities are evaluating IGCC’s suitability for base-load capacity additions. This recent surge of attention to IGCC power generation is creating a growing demand for experience with the analysis, operation, and control of commercial-scale IGCC plants. To meet this need, the National Energy Technology Laboratory (NETL) has launched a project to develop a generic, full-scope, IGCC dynamic plant simulator for use in establishing a state-of-the-art simulator training center at West Virginia University’s (WVU) National Research Center for Coal and Energy (NRCCE). The IGCC Dynamic Simulator & Training (DS&T) Center will be established under the auspices of the Collaboratory for Process & Dynamic Systems Modeling (“Collaboratory”) organized between NETL, WVU, the University of Pittsburgh, and Carnegie Mellon University.

Erbes, M.R. (Enginomix, LLC); Zitney, S.E

2006-09-01T23:59:59.000Z

163

Dynamic simulation for IGCC process and control design  

Science Conference Proceedings (OSTI)

Detailed dynamic simulation analysis is a valuable tool that increases the understanding of unit interactions and control system performance in a complex integrated gasification combined-cycle (IGCC) plant. The Sarlux integrated gasification combined cycle (IGCC) plant must simultaneously satisfy electrical power and refinery hydrogen and steam demands (trigeneration gasification). The plant`s gasifier, heat recovery, sulfur removal, hydrogen recovery and steam power generation units are highly integrated and require coordinated control. In this study, dynamic simulation provides insights into the behavior of the process and combined cycle units during normal and upset conditions. The dynamic simulation is used to design a control system that drives the gasifiers to satisfy power, steam and hydrogen demands before a load change or upset is detected by the syngas pressure controller. At the study conclusion, the model will demonstrate how the IGCC plant will respond to the contractual maximum load change rate and process upsets. The study tests the basic process and control system design during the project engineering phase to minimize startup troubleshooting and expensive field changes.

Depew, C.; Martinez, A. [Fluor Daniel, Irvine, CA (United States); Collodi, G.; Meloni, R. [Snamprogetti, Milan (Italy)

1998-01-01T23:59:59.000Z

164

Study of the Effects of Obstacles in Liquefied Natural Gas (LNG) Vapor Dispersion using CFD Modeling  

E-Print Network (OSTI)

The evaluation of the potential hazards related with the operation of an LNG terminal includes possible release scenarios with the consequent flammable vapor dispersion within the facility; therefore, it is important to know the behavior of this phenomenon through the application of advanced simulation tools. Computational Fluid Dynamic (CFD) tools are often used to estimate the exclusion zones in an event of accidental LNG spill. In practice these releases are more likely to occur in the confines of complex geometries with solid obstacles such as LNG terminals, and LNG processing plants. The objective of this research is to study the effects that different obstacles have over the LNG vapor dispersion and the safety distance reduction caused by enhanced mixing. Through parametric analysis it is demonstrated that height, width and shape of the obstacles play an important role in the vapor concentration reduction. The findings of this research may be applied in the design stage of an LNG terminal, to improve the design of passive barriers, and for designing better layout configurations for storage tanks. Simulations results performed with FLACS (Flame Acceleration Simulator), a CFD solver, confirmed that these applications help to reduce safety distances.

Ruiz Vasquez, Roberto

2012-08-01T23:59:59.000Z

165

Molecular Dynamics Simulations of Temperature Equilibration in Dense Hydrogen  

DOE Green Energy (OSTI)

The temperature equilibration rate in dense hydrogen (for both T{sub i} > T{sub e} and T{sub i} < T{sub e}) has been calculated with large-scale molecular dynamics simulations for temperatures between 10 and 300 eV and densities between 10{sup 20}/cc to 10{sup 24}/cc. Careful attention has been devoted to convergence of the simulations, including the role of semiclassical potentials. We find that for Coulomb logarithms L {approx}> 1, Brown-Preston-Singleton [Brown et al., Phys. Rep. 410, 237 (2005)] with the sub-leading corrections and the fit of Gericke-Murillo-Schlanges [Gericke et al., PRE 65, 036418 (2003)] to the T-matrix evaluation of the collision operator, agrees with the MD data to within the error bars of the simulation. For more strongly-coupled plasmas where L {approx}< 1, our numerical results are consistent with the fit of Gericke-Murillo-Schlanges.

Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M; Benedict, L; Hau-Riege, S; Langdon, A; London, R

2008-02-14T23:59:59.000Z

166

Lightweight computational steering of very large scale molecular dynamics simulations  

Science Conference Proceedings (OSTI)

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

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

1996-09-01T23:59:59.000Z

167

Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten  

E-Print Network (OSTI)

Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten Xue Yang using classical molecular dynamic methods. " Low energy deuterium atoms tend to affix to high environment. The deuterium bombardment of monocrystalline tungsten was modeled by molecular dynamics

Harilal, S. S.

168

Visualization of Folktales on a Map by Coupling Dynamic DEVS Simulation within Google Earth  

E-Print Network (OSTI)

Visualization of Folktales on a Map by Coupling Dynamic DEVS Simulation within Google Earth, Google Earth API, Dynamic variable structures Abstract: This paper deals with dynamic visualization of folktales on a map. The visualization is performed using a coupling of dynamic simulation with the google

Paris-Sud XI, Université de

169

Comparative Evaluation of an Eulerian CFD and Gaussian Plume Models Based on Prairie Grass Dispersion Experiment  

Science Conference Proceedings (OSTI)

A theoretical and statistical comparison of a three-dimensional computational fluid dynamics (CFD) model with two Gaussian plume models is proposed on the Prairie Grass data field experiment for neutral conditions, using both maximum arcwise ...

E. Demael; B. Carissimo

2008-03-01T23:59:59.000Z

170

Computational fluid dynamics applications to improve crop production systems  

Science Conference Proceedings (OSTI)

Computational fluid dynamics (CFD), numerical analysis and simulation tools of fluid flow processes have emerged from the development stage and become nowadays a robust design tool. It is widely used to study various transport phenomena which involve ... Keywords: Decision support tools, Greenhouse, Harvesting machines, Sprayers, Tillage

T. Bartzanas; M. Kacira; H. Zhu; S. Karmakar; E. Tamimi; N. Katsoulas; In Bok Lee; C. Kittas

2013-04-01T23:59:59.000Z

171

A scalable parallel algorithm for dynamic range-limited n-tuple computation in many-body molecular dynamics simulation  

Science Conference Proceedings (OSTI)

Recent advancements in reactive molecular dynamics (MD) simulations based on many-body interatomic potentials necessitate efficient dynamic n-tuple computation, where a set of atomic n-tuples within a given spatial range is constructed ... Keywords: dynamic range-limited n-tuple computation, molecular dynamics, parallel computing

Manaschai Kunaseth, Rajiv K. Kalia, Aiichiro Nakano, Ken-ichi Nomura, Priya Vashishta

2013-11-01T23:59:59.000Z

172

Development of directional capabilities to an ultradeep water dynamic kill simulator and simulations runs  

E-Print Network (OSTI)

The world is dependent on the production of oil and gas, and every day the demand increases. Technologies have to keep up with the demand of this resource to keep the world running. Since hydrocarbons are finite and will eventually run out, the increasing demand of oil and gas is the impetus to search for oil in more difficult and challenging areas. One challenging area is offshore in ultradeep water, with water depths greater than 5000 ft. This is the new arena for drilling technology. Unfortunately with greater challenges there are greater risks of losing control and blowing out a well. A dynamic kill simulator was developed in late 2004 to model initial conditions of a blowout in ultradeep water and to calculate the minimum kill rate required to kill a blowing well using the dynamic kill method. The simulator was simple and efficient, but had limitations; only vertical wells could be simulated. To keep up with technology, modifications were made to the simulator to model directional wells. COMASim (Cherokee, Offshore Technology Research Center, Minerals Management Service, Texas A&M Simulator) is the name of the dynamic kill simulator. The new version, COMASim1.0, has the ability to model almost any type of wellbore geometry when provided the measured and vertical depths of the well. Eighteen models with varying wellbore geometry were simulated to examine the effects of wellbore geometry on the minimum kill rate requirement. The main observation was that lower kill rate requirement was needed in wells with larger measured depth. COMASim 1.0 cannot determine whether the inputs provided by the user are practical; COMASim 1.0 can only determine if the inputs are incorrect, inconsistent or cannot be computed. If unreasonable drilling scenarios are input, unreasonable outputs will result. COMASim1.0 adds greater functionality to the previous version while maintaining the original framework and simplicity of calculations and usage.

Meier, Hector Ulysses

2005-08-01T23:59:59.000Z

173

Preliminary analysis of the dynamic heliosphere by MHD simulations  

SciTech Connect

A preliminary analysis of the dynamic heliosphere to estimate the termination shock (TS) distance from the sun around the time when Voyager 1 passed the termination shock at December 16, 2004 is performed by using MHD simulations. For input to this simulation, we use the Voyager 2 solar-wind data. We first find a stationary solution of the 3-D outer heliosphere by assigning a set of LISM parameters as our outer boundary conditions and then the dynamical analysis is performed. The model TS crossing is within 6 months of the observed date. The TS is pushed outward every time a high ram-pressure solar wind pulse arrives. After the end of the high ram-pressure wind, the TS shock shrinks inward. When the last Halloween event passed through the TS at DOY 250, 2004, the TS began to shrink inward very quickly and the TS crossed V1. The highest inward speed of the TS is over 400 km/s. The high ram-pressure solar wind transmitted through the TS becomes a high thermal-pressure plasma in the heliosheath, acting to push the TS inward. This suggests that the position of the TS is determined not only by the steady-state pressure balance condition between the solar wind ram-pressure and the LISM pressure, but by the dynamical ram pressure too. The period when the high ram-pressure solar wind arrives at the TS shock seems to correspond to the period of the TS particle event (Stone et al, 2005, Decker et al., 2005). The TS crossing date will be revised in future simulations using a more appropriate set of parameters for the LISM. This will enable us to undertake a detailed comparison of the simulation results with the TS particle events.

Washimi, H.; Zank, G. P. [Institute of Geophysics and Planetary Physics (IGPP), University of California, Riverside, CA 92521 (United States); Tanaka, T. [Faculty of Science, Kyushu University, Hakozaki, Fukuoka 812-8581 (Japan)

2006-09-26T23:59:59.000Z

174

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

DOE Data Explorer (OSTI)

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

Plimpton, Steve; Thompson, Aidan; Crozier, Paul

175

Standard Problems for CFD Validation for NGNP - Status Report  

DOE Green Energy (OSTI)

The U.S. Department of Energy (DOE) is conducting research and development to support the resurgence of nuclear power in the United States for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The project is called the Next Generation Nuclear Plant (NGNP) Project, which is based on a Generation IV reactor concept called the very high temperature reactor (VHTR). The VHTR will be of the prismatic or pebble bed type; the former is considered herein. The VHTR will use helium as the coolant at temperatures ranging from 250°C to perhaps 1000°C. While computational fluid dynamics (CFD) has not previously been used for the safety analysis of nuclear reactors in the United States, it is being considered for existing and future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal operational and accident situations. The “Standard Problem” is an experimental data set that represents an important physical phenomenon or phenomena, whose selection is based on a phenomena identification and ranking table (PIRT) for the reactor in question. It will be necessary to build a database that contains a number of standard problems for use to validate CFD and systems analysis codes for the many physical problems that will need to be analyzed. The first two standard problems that have been developed for CFD validation consider flow in the lower plenum of the VHTR and bypass flow in the prismatic core. Both involve scaled models built from quartz and designed to be installed in the INL’s matched index of refraction (MIR) test facility. The MIR facility employs mineral oil as the working fluid at a constant temperature. At this temperature, the index of refraction of the mineral oil is the same as that of the quartz. This provides an advantage to the optics used for data gathering. Particle image velocimetry (PIV) is used to take the data. The first standard problem represents several flow physics expected to be present in the lower plenum of the prismatic VHTR. In the lower plenum, heated helium coolant in the form of jets issues downward into the plenum and is then forced to turn ninety degrees and flow toward the exit duct. The lower plenum is filled with cylindrical graphite posts that hold up the core. Figure S-1 provides a plan view of the lower plenum. The red circles represent support posts holding up columns of heated blocks. Grey circles represent support posts under columns of reflector blocks. Helium enters the lower plenum at the junctions of the hexagonal blocks.

Richard W. Johnson; Richard R. Schultz

2010-08-01T23:59:59.000Z

176

Force spectroscopy of polymer desorption: Theory and Molecular Dynamics simulation  

E-Print Network (OSTI)

Forced detachment of a single polymer chain, strongly-adsorbed on a solid substrate, is investigated by two complementary methods: a coarse-grained analytical dynamical model, based on the Onsager stochastic equation, and Molecular Dynamics (MD) simulations with Langevin thermostat. The suggested approach makes it possible to go beyond the limitations of the conventional Bell-Evans model. We observe a series of characteristic force spikes when the pulling force is measured against the cantilever displacement during detachment at constant velocity $v_c$ (displacement control mode) and find that the average magnitude of this force increases as $v_c$ grows. The probability distributions of the pulling force and the end-monomer distance from the surface at the moment of final detachment are investigated for different adsorption energy $\\epsilon$ and pulling velocity $v_c$. Our extensive MD-simulations validate and support the main theoretical findings. Moreover, the simulation reveals a novel behavior: for a strong-friction and massive cantilever the force spikes pattern is smeared out at large $v_c$. As a challenging task for experimental bio-polymers sequencing in future we suggest the fabrication of stiff, super-light, nanometer-sized AFM probe.

J. Paturej; J. L. A. Dubbeldam; V. G. Rostiashvili; A. Milchev; T. A. Vilgis

2013-10-14T23:59:59.000Z

177

A CFD/CSD interaction methodology for aircraft wings  

DOE Green Energy (OSTI)

With advanced subsonic transports and military aircraft operating in the transonic regime, it is becoming important to determine the effects of the coupling between aerodynamic loads and elastic forces. Since aeroelastic effects can significantly impact the design of these aircraft, there is a strong need in the aerospace industry to predict these interactions computationally. Such an analysis in the transonic regime requires high fidelity computational fluid dynamics (CFD) analysis tools, due to the nonlinear behavior of the aerodynamics in the transonic regime and also high fidelity computational structural dynamics (CSD) analysis tools. Also, there is a need to be able to use a wide variety of CFD and CSD methods to predict aeroelastic effects. Since source codes are not always available, it is necessary to couple the CFD and CSD codes without alteration of the source codes. In this study, an aeroelastic coupling procedure is developed to determine the static aeroelastic response of aircraft wings using any CFD and CSD code with little code integration. The aeroelastic coupling procedure is demonstrated on an F/A-18 Stabilator using NASTD (an in-house McDonnell Douglas CFD code) and NASTRAN. In addition, the Aeroelastic Research Wing (ARW-2) is used for demonstration of the aeroelastic coupling procedure by using ENSAERO (NASA Ames Research Center CFD code) and a finite element wing-box code. The results obtained from the present study are compared with those available from an experimental study conducted at NASA Langley Research Center and a study conducted at NASA Ames Research Center using ENSAERO and modal superposition. The results compare well with experimental data.

Bhardwaj, M.K.; Kapania, R.K. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States); Reichenbach, E. [Boeing Co., St. Louis, MO (United States); Guruswamy, G.P. [NASA, Moffett Field, CA (United States). Ames Research Center

1998-01-01T23:59:59.000Z

178

Dynamic Simulation and Optimization of Nuclear Hydrogen Production Systems  

DOE Green Energy (OSTI)

This project is part of a research effort to design a hydrogen plant and its interface with a nuclear reactor. This project developed a dynamic modeling, simulation and optimization environment for nuclear hydrogen production systems. A hybrid discrete/continuous model captures both the continuous dynamics of the nuclear plant, the hydrogen plant, and their interface, along with discrete events such as major upsets. This hybrid model makes us of accurate thermodynamic sub-models for the description of phase and reaction equilibria in the thermochemical reactor. Use of the detailed thermodynamic models will allow researchers to examine the process in detail and have confidence in the accurary of the property package they use.

Paul I. Barton; Mujid S. Kaximi; Georgios Bollas; Patricio Ramirez Munoz

2009-07-31T23:59:59.000Z

179

Dynamic computer simulation of the Fort St. Vrain steam turbines  

SciTech Connect

A computer simulation is described for the dynamic response of the Fort St. Vrain nuclear reactor regenerative intermediate- and low-pressure steam turbines. The fundamental computer-modeling assumptions for the turbines and feedwater heaters are developed. A turbine heat balance specifying steam and feedwater conditions at a given generator load and the volumes of the feedwater heaters are all that are necessary as descriptive input parameters. Actual plant data for a generator load reduction from 100 to 50% power (which occurred as part of a plant transient on November 9, 1981) are compared with computer-generated predictions, with reasonably good agreement.

Conklin, J.C.

1983-01-01T23:59:59.000Z

180

Processed Splitting Algorithms for Rigid-Body Molecular Dynamics Simulations  

E-Print Network (OSTI)

A new approach for integration of motion in many-body systems of interacting polyatomic molecules is proposed. It is based on splitting time propagation of pseudo-variables in a modified phase space, while the real translational and orientational coordinates are decoded by processing transformations. This allows to overcome the barrier on the order of precision of the integration at a given number of force-torque evaluations per time step. Testing in dynamics of water versus previous methods shows that the obtained algorithms significantly improve the accuracy of the simulations without extra computational costs.

Igor P. Omelyan

2008-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "dynamics cfd simulations" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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181

Molecular Dynamics Simulation of Collisions between Hydrogen and Graphite  

E-Print Network (OSTI)

Abstract. Hydrogen adsorption by graphite is examined by classical molecular dynamics simulation using a modified Brenner REBO potential. Such interactions are typical in chemical sputtering experiments, and knowledge of the fundamental behavior of hydrogen and graphene in collisional conditions is essential for modeling the sputtering mechanism. The hydrogen adsorption rate is found to be dependent on the incident hydrogen energy and not on graphene temperature. Rather than destroying the graphene, hydrogen incidence at energies of less than 100 eV can be classified into three regimes of adsorption, reflection and penetration through one or more graphene layers. Incidence at the lowest energies is shown to distort the graphene structure. 1.

unknown authors

2005-01-01T23:59:59.000Z

182

Molecular dynamics simulation of hydrogen diffusion in titanium  

National Nuclear Security Administration (NNSA)

9: Computation Physics 9: Computation Physics Atomistic Simulation of Hydrogen Diffusion in Titanium. Alexandr S. Rokhmanenkov, Alexey Yu. Kuksin, and Vladimir V. Stegailov All-Russia Research Institute of Automatics, Moscow 125412, Russia rohmanenkov@gmail.com Summary Study of the behavior of hydrogen in metals and alloys. The study is based on classical molecular dynamics (MD) and density functional theory (DFT) calculations. Study of the behavior of hydrogen in metals and alloys is of great importance due to the practical uses of hydrogen-metal systems for absorption of nuclear radiation, in neutron sources, for storage of hydrogen, or as catalyzers. This work is devoted to atomistic simulation of hydrogen diffusion in titanium hydrides and the effect of stresses and lattice defects on diffusivity.

183

Structural Modeling and Molecular Dynamics Simulation of the Actin Filament  

DOE Green Energy (OSTI)

Actin is a major structural protein of the eukaryotic cytoskeleton and enables cell motility. Here, we present a model of the actin filament (F-actin) that not only incorporates the global structure of the recently published model by Oda et al. but also conserves internal stereochemistry. A comparison is made using molecular dynamics simulation of the model with other recent F-actin models. A number of structural determents such as the protomer propeller angle, the number of hydrogen bonds, and the structural variation among the protomers are analyzed. The MD comparison is found to reflect the evolution in quality of actin models over the last 6 years. In addition, simulations of the model are carried out in states with both ADP or ATP bound and local hydrogen-bonding differences characterized.

Splettstoesser, Thomas [University of Heidelberg; Holmes, Kenneth [Max Planck Institute, Heidelberg, Germany; Noe, Frank [DFG Research Center Matheon, FU Berlin, Germany; Smith, Jeremy C [ORNL

2011-01-01T23:59:59.000Z

184

Dynamic simulation and performance evaluation of fossil power plants  

Science Conference Proceedings (OSTI)

A dynamic performance model of a standard fossil-fired power plant has been developed. The model contains major components in a plant, including pulverizer, boiler, superheaters, reheaters, economizer, attemperators, pumps, valves, pipings, condenser, turbines, deaerator and low/high pressure feedwater heaters. The EPRI Modular Modeling System (MMS) and Boeing Computer Services' Engineering Analysis System (EASY5) simulation language were used in the analysis. A system control model also developed to simulate the plant control and perform the necessary control functions. The plant model has a general structure and can readily be modified to simulate a specific power plant. To demonstrate the utility of the model, simulation calculations were carried out for a standard coal-fired power plant of the Middle South Services (MSS) during steady state and transient modes of operation. The results were obtained for full load and reduced loads down to 35 percent. In general, good agreement was obtained with the plant heat balance data. 15 refs., 35 figs., 11 tabs.

Hashemi, A.; Lin, C.S.; Munis, A.; Lee, S. (Science Applications International Corp., Hermosa Beach, CA (USA))

1988-12-01T23:59:59.000Z

185

RIAPMTQ/Impact : beam-dynamics simulation tool for RIA.  

Science Conference Proceedings (OSTI)

We have developed a pair of multiparticle beam dynamics codes for end-to-end computer simulations of the proposed RIA heavy-ion driver linac. The two codes are: (1) an adaptation of PARMTEQ called RIAPMTQ for the normal-conducting-linac front end, and (2) IMPACT for the superconducting linac. The codes run on a PC as well as on parallel supercomputing platforms such as NERSC at LBNL. The parallel capability allows us to run simulations with large numbers of macroparticles for the computation of beam halo and beam-losses. The codes are being benchmarked for rms beam properties against previously existing codes at ANL and MSU. The work is being performed by a collaboration including LANL, LBNL, ANL, and Michigan State University (MSU). In this paper we present an overview, the status of the work, comparison of simulation results from RIAPMTQ and the ANL code TRACK for the ANL front-end design, and the first RIAPMTQ/IMPACT end-to-end multiprocessor simulation for the MSU design.

Wangler, T. P.; Billen, J. H.; Garnett, R. W.; Qiang, J.; Ryne, R.; Crandall, K. R.; Ostroumov, P.; Aseev, V. N.; Mustapha, B.; York, R. C.; Wu, X.; Zhao, Q.; Gorelov, D.; Doleans, M.; Physics; LANL; Tech Source; Michigan State Univ.

2006-01-01T23:59:59.000Z

186

A Dissipative-Particle-Dynamics Model for Simulating Dynamics of Charged Colloid  

E-Print Network (OSTI)

A mesoscopic colloid model is developed in which a spherical colloid is represented by many interacting sites on its surface. The hydrodynamic interactions with thermal fluctuations are taken accounts in full using Dissipative Particle Dynamics, and the electrostatic interactions are simulated using Particle-Particle-Particle Mesh method. This new model is applied to investigate the electrophoretic mobility of a charged colloid under an external electric field, and the influence of salt concentration and colloid charge are systematically studied. The simulation results show good agreement with predictions from the electrokinetic theory.

Jiajia Zhou; Friederike Schmid

2013-11-05T23:59:59.000Z

187

Pseudo-random number generation for Brownian Dynamics and Dissipative Particle Dynamics simulations on GPU devices  

Science Conference Proceedings (OSTI)

Highlights: {yields} Molecular Dynamics codes implemented on GPUs have achieved two-order of magnitude computational accelerations. {yields} Brownian Dynamics and Dissipative Particle Dynamics simulations require a large number of random numbers per time step. {yields} We introduce a method for generating small batches of pseudorandom numbers distributed over many threads of calculations. {yields} With this method, Dissipative Particle Dynamics is implemented on a GPU device without requiring thread-to-thread communication. - Abstract: Brownian Dynamics (BD), also known as Langevin Dynamics, and Dissipative Particle Dynamics (DPD) are implicit solvent methods commonly used in models of soft matter and biomolecular systems. The interaction of the numerous solvent particles with larger particles is coarse-grained as a Langevin thermostat is applied to individual particles or to particle pairs. The Langevin thermostat requires a pseudo-random number generator (PRNG) to generate the stochastic force applied to each particle or pair of neighboring particles during each time step in the integration of Newton's equations of motion. In a Single-Instruction-Multiple-Thread (SIMT) GPU parallel computing environment, small batches of random numbers must be generated over thousands of threads and millions of kernel calls. In this communication we introduce a one-PRNG-per-kernel-call-per-thread scheme, in which a micro-stream of pseudorandom numbers is generated in each thread and kernel call. These high quality, statistically robust micro-streams require no global memory for state storage, are more computationally efficient than other PRNG schemes in memory-bound kernels, and uniquely enable the DPD simulation method without requiring communication between threads.

Phillips, Carolyn L. [Applied Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Anderson, Joshua A. [Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Glotzer, Sharon C., E-mail: sglotzer@umich.edu [Applied Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Material Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-08-10T23:59:59.000Z

188

Technical Review of the CENWP Computational Fluid Dynamics Model of the John Day Dam Forebay  

Science Conference Proceedings (OSTI)

The US Army Corps of Engineers Portland District (CENWP) has developed a computational fluid dynamics (CFD) model of the John Day forebay on the Columbia River to aid in the development and design of alternatives to improve juvenile salmon passage at the John Day Project. At the request of CENWP, Pacific Northwest National Laboratory (PNNL) Hydrology Group has conducted a technical review of CENWP's CFD model run in CFD solver software, STAR-CD. PNNL has extensive experience developing and applying 3D CFD models run in STAR-CD for Columbia River hydroelectric projects. The John Day forebay model developed by CENWP is adequately configured and validated. The model is ready for use simulating forebay hydraulics for structural and operational alternatives. The approach and method are sound, however CENWP has identified some improvements that need to be made for future models and for modifications to this existing model.

Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.

2010-12-01T23:59:59.000Z

189

Molecular Dynamics Simulations to Compute the Bulk Response of Amorphous PMMA  

E-Print Network (OSTI)

Molecular Dynamics Simulations to Compute the Bulk Response of Amorphous PMMA S.B. Sane* , T. Cagin of molecular dynamics computations and corresponding values of laboratory measurements are compared to assess computational methods has offered the potential for "molecular dynamics" simulations to predict the mechanical

Goddard III, William A.

190

The application of discrete event simulation and system dynamics in the logistics and supply chain context  

Science Conference Proceedings (OSTI)

Discrete event simulation (DES) and system dynamics (SD) are two modelling approaches widely used as decision support tools in logistics and supply chain management (LSCM). A widely held belief exists that SD is mostly used to model problems at a strategic ... Keywords: Comparison of methods, Discrete-event simulation, Logistics and supply chain management, Simulation modelling, System dynamics

Antuela A. Tako; Stewart Robinson

2012-03-01T23:59:59.000Z

191

Ion dynamics at supercritical quasi-parallel shocks: Hybrid simulations  

Science Conference Proceedings (OSTI)

By separating the incident ions into directly transmitted, downstream thermalized, and diffuse ions, we perform one-dimensional (1D) hybrid simulations to investigate ion dynamics at a supercritical quasi-parallel shock. In the simulations, the angle between the upstream magnetic field and shock nominal direction is {theta}{sub Bn}=30 Degree-Sign , and the Alfven Mach number is M{sub A}{approx}5.5. The shock exhibits a periodic reformation process. The ion reflection occurs at the beginning of the reformation cycle. Part of the reflected ions is trapped between the old and new shock fronts for an extended time period. These particles eventually form superthermal diffuse ions after they escape to the upstream of the new shock front at the end of the reformation cycle. The other reflected ions may return to the shock immediately or be trapped between the old and new shock fronts for a short time period. When the amplitude of the new shock front exceeds that of the old shock front and the reformation cycle is finished, these ions become thermalized ions in the downstream. No noticeable heating can be found in the directly transmitted ions. The relevance of our simulations to the satellite observations is also discussed in the paper.

Su Yanqing; Lu Quanming; Gao Xinliang; Huang Can; Wang Shui [CAS Key Laboratory of Basic Plasma Physics, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China)

2012-09-15T23:59:59.000Z

192

Applications of automatic differentiation in CFD  

DOE Green Energy (OSTI)

Automated multidisciplinary design of aircraft requires the optimization of complex performance objectives with respect to a number of design parameters and constraints. The effect of these independent design variables on the system performance criteria can be quantified in terms of sensitivity derivatives for the individual discipline simulation codes. Typical advanced CFD codes do not provide such derivatives as part of a flow solution. These derivatives are expensive to obtain by divided differences from perturbed solutions, and may be unreliable, particularly for noisy functions. In this paper, automatic differentiation has been investigated as a means of extending iterative CFD codes with sensitivity derivatives. In particular, the ADIFOR automatic differentiator has been applied to the 3-D, thin-layer Navier-Stokes, multigrid flow solver called TLNS3D coupled with the WTCO wing grid generator. Results of a sequence of efforts in which TLNS3D has been successfully augmented to compute a variety of sensitivities are presented. It is shown that sensitivity derivatives can be obtained accurately and efficiently using ADIFOR, although significant advances are necessary for the efficiency of ADIFOR-generated derivative code to become truly competitive with hand-differentiated code.

Carle, A. [Rice Univ., Houston, TX (United States); Green, L.L.; Newman, P.A. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Bischof, C.H. [Argonne National Lab., IL (United States)

1994-06-01T23:59:59.000Z

193

A Dynamic Wind Turbine Simulator of the Wind Turbine Generator System  

Science Conference Proceedings (OSTI)

To study dynamic performances of wind turbine generator system (WTGS), and to determine the control structures in laboratory. The dynamic torque generated by wind turbine (WT) must be simulated. In there paper, a dynamic wind turbine emulator (WTE) is ... Keywords: dynamic wind turbine emulation, wind shear, tower shadow, torque compensation

Lei Lu; Zhen Xie; Xing Zhang; Shuying Yang; Renxian Cao

2012-01-01T23:59:59.000Z

194

Superconducting Circuits for Quantum Simulation of Dynamical Gauge Fields  

E-Print Network (OSTI)

We describe a superconducting-circuit lattice design for the implementation and simulation of dynamical lattice gauge theories. We illustrate our proposal by analyzing a one-dimensional U(1) quantum-link model, where superconducting qubits play the role of matter fields on the lattice sites and the gauge fields are represented by two coupled microwave resonators on each link between neighboring sites. A detailed analysis of a minimal experimental protocol for probing the physics related to string breaking effects shows that despite the presence of decoherence in these systems, distinctive phenomena from condensed-matter and high-energy physics can be visualized with state-of-the-art technology in small superconducting-circuit arrays.

D. Marcos; P. Rabl; E. Rico; P. Zoller

2013-06-07T23:59:59.000Z

195

Video of Simulation of the Dynamics of a Wind-Driven Fire in a ...  

Science Conference Proceedings (OSTI)

Simulation of the Dynamics of a Wind-Driven Fire in a Ranch-Style House – Texas. Wind Driven Fire in Home, Texas, 2009. ...

2013-06-28T23:59:59.000Z

196

Web-based simulation 2: performance prediction of dynamic component substitutions  

Science Conference Proceedings (OSTI)

The Web-based Environment for Systems Engineering (wese) is a web-based modeling and simulation environment in which the level of abstraction of a model can be configured statically (prior to simulation) or dynamically (during ...

Dhananjai M. Rao; Philip A. Wilsey

2002-12-01T23:59:59.000Z

197

Dynamic parameterization to simulate DIN export due to gypsy moth defoliation  

Science Conference Proceedings (OSTI)

A module of dynamic parameterization is added into the HSPF watershed software for simulation of dissolved inorganic nitrogen (DIN) export from forest associated with gypsy moth defoliation. It simulates a changing ecosystem following the breakout of ...

Ping Wang; Lewis C. Linker; Keith N. Eshleman

2003-06-01T23:59:59.000Z

198

Consequences of Urban Stability Conditions for Computational Fluid Dynamics Simulations of Urban Dispersion  

Science Conference Proceedings (OSTI)

The validity of omitting stability considerations when simulating transport and dispersion in the urban environment is explored using observations from the Joint Urban 2003 field experiment and computational fluid dynamics simulations of that ...

Julie K. Lundquist; Stevens T. Chan

2007-07-01T23:59:59.000Z

199

Time-domain non-Monte Carlo noise simulation for nonlinear dynamic circuits with arbitrary excitations  

Science Conference Proceedings (OSTI)

A new, time-domain, non-Monte Carlo method for computer simulation of electrical noise in nonlinear dynamic circuits with arbitrary excitations is presented. This time-domain noise simulation ...

Alper Demir; Edward W. Y. Liu; Alberto L. Sangiovanni-Vincentelli

1994-11-01T23:59:59.000Z

200

Surface detection, meshing and analysis during large molecular dynamics simulations  

SciTech Connect

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

Dupuy, L M; Rudd, R E

2005-08-01T23:59:59.000Z

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


201

Fluidic Catalytic Cracking Power Recovery Dynamic Computer Simulation  

E-Print Network (OSTI)

Fluidic Cat Crackers (FCC) using the catalyst regeneration cycle are candidates for more power efficient operation by the use of high temperature dirty gas expanders. In a previous paper, a computer simulation was described for the steady state operation of the primary mechanical components, specifically the axial compressor and hot gas expander. The present work expands upon the steady state model to add the dynamic characteristics of these elements as well as the effects of the controlling process valves. In many applications the expander will develop more power than the axial compressor can absorb. A power absorbing source, specifically an electrical generator, converts the mechanical excess power into electrical energy. A review of the mechanical equipment and the electrical generator operating modes and controls is needed so that the process designer and operator will know how the system will respond if process upsets were to occur. The program code developed can simulate these elements for specific processes and demonstrate the logic control scheme proposed by the process designer. This information will therefore allow the process operator, process designer and mechanical equipment supplier an understanding of the interplay of the system control elements and define specific operating limits.

Samurin, N. A.

1980-01-01T23:59:59.000Z

202

Enhanced molecular dynamics for simulating porous interphase layers in batteries.  

DOE Green Energy (OSTI)

Understanding charge transport processes at a molecular level using computational techniques is currently hindered by a lack of appropriate models for incorporating anistropic electric fields in molecular dynamics (MD) simulations. An important technological example is ion transport through solid-electrolyte interphase (SEI) layers that form in many common types of batteries. These layers regulate the rate at which electro-chemical reactions occur, affecting power, safety, and reliability. In this work, we develop a model for incorporating electric fields in MD using an atomistic-to-continuum framework. This framework provides the mathematical and algorithmic infrastructure to couple finite element (FE) representations of continuous data with atomic data. In this application, the electric potential is represented on a FE mesh and is calculated from a Poisson equation with source terms determined by the distribution of the atomic charges. Boundary conditions can be imposed naturally using the FE description of the potential, which then propagates to each atom through modified forces. The method is verified using simulations where analytical or theoretical solutions are known. Calculations of salt water solutions in complex domains are performed to understand how ions are attracted to charged surfaces in the presence of electric fields and interfering media.

Zimmerman, Jonathan A.; Wong, Bryan Matthew; Jones, Reese E.; Templeton, Jeremy Alan; Lee, Jonathan (Rice University, Houston, TX)

2009-10-01T23:59:59.000Z

203

Coupling methodology of 1D finite difference and 3D finite volume CFD codes based on the Method of Characteristics  

Science Conference Proceedings (OSTI)

This paper describes the methodology followed to perform a co-simulation between 1D (OpenWAM) and 3D (FLUENT) CFD codes. The Method of Characteristics (MoC) has been chosen to transfer the information between the two domains by properly updating the ... Keywords: 1D modeling, 1D-3D coupling, CFD simulation, Co-simulation, Method of Characteristics, User defined function

J. Galindo; A. Tiseira; P. Fajardo; R. Navarro

2011-10-01T23:59:59.000Z

204

Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films  

E-Print Network (OSTI)

Molecular Dynamics (MD) simulations of nano-scale flows typically utilize fixed lattice crystal interactions between the fluid and stationary wall molecules. This approach cannot properly model thermal interactions at the wall-fluid interface. In order to properly simulate the flow and heat transfer in nano-scale channels, an interactive thermal wall model is developed. Using this model, the Fourier’s law of heat conduction is verified in a 3.24 nm height channel, where linear temperature profiles with constant thermal conductivity is obtained. The thermal conductivity is verified using the predictions of Green-Kubo theory. MD simulations at different wall wettability ( ??f /? ) and crystal bonding stiffness values (K) have shown temperature jumps at the liquid/solid interface, corresponding to the well known Kapitza resistance. Using systematic studies, the thermal resistance length at the interface is characterized as a function of the surface wettability, thermal oscillation frequency, wall temperature and thermal gradient. An empirical model for the thermal resistance length, which could be used as the jump-coefficient of a Navier boundary condition, is developed. Temperature distributions in the nano-channels are predicted using analytical solution of the continuum heat conduction equation subjected to the new temperature jump condition, and validated using the MD results. Momentum and heat transfer in shear driven nanochannel flows are also investigated. Work done by the viscous stresses heats the fluid, which is dissipated through the channel walls, maintained at isothermal conditions. Spatial variations in the fluid density, kinematic viscosity, shear- and energy dissipation rates are presented. The energy dissipation rate is almost a constant for ??f /? < 0.6, which results in parabolic temperature profiles in the domain with temperature jumps due to the Kapitza resistance at the liquid/solid interfaces. Using the energy dissipation rates predicted by MD simulations and the continuum energy equation subjected to the temperature jump boundary conditions developed in this study, the analytical solutions are obtained for the temperature profiles, which agree well with the MD results.

Kim, Bo Hung

2009-05-01T23:59:59.000Z

205

Low Energy Buildings: CFD Techniques for Natural Ventilation and Thermal  

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

Low Energy Buildings: CFD Techniques for Natural Ventilation and Thermal Low Energy Buildings: CFD Techniques for Natural Ventilation and Thermal Comfort Prediction Speaker(s): Malcolm Cook Date: February 14, 2013 - 12:00pm Location: 90-3122 Seminar Host/Point of Contact: Michael Wetter Malcolm's presentation will cover both his research and consultancy activities. This will cover the work he has undertaken during his time spent working with architects on low energy building design, with a particular focus on natural ventilation and passive cooling strategies, and the role computer simulation can play in this design process. Malcolm will talk about the simulation techniques employed, as well as the innovative passive design principles that have led to some of the UK's most energy efficient buildings. In addition to UK building projects, the talk will

206

A Numerical Model for the Dynamic Simulation of a Recirculation Single-Effect Absorption Chiller  

E-Print Network (OSTI)

A Numerical Model for the Dynamic Simulation of a Recirculation Single- Effect Absorption Chiller A dynamic model for the simulation of a new single-effect water/lithium bromide absorption chiller. Keywords: absorption; chiller; modelling; transient; water-lithium bromide; falling film hal-00713904

Recanati, Catherine

207

Dynamic simulation model for non-supplementary firing triple-pressure heat recovery steam generator  

Science Conference Proceedings (OSTI)

By using the modular modeling method, a real-time dynamic simulation model for the non-supplementary tri-pressure reheat Heat Recovery Steam Generator (HRSG) is developed. On the basis of mass and energy conservation law, the paper discusses the model ... Keywords: HRSG, dynamic model, modular modelling, simulation

Ning Cui; Bing-Shu Wang; Xiang-Yang Gong; Jian-Qiang Gao

2007-10-01T23:59:59.000Z

208

The implementation of polarizable and flexible models in molecular dynamics simulations  

Science Conference Proceedings (OSTI)

We discuss a new methodology for implementing polarizable and flexible molecular models - the fluctuating charge and intramolecular potential (fCINTRA) method - in Molecular Dynamics (MD) simulations. An example has been provided for ethanol. In these ... Keywords: message passing interface, molecular dynamics simulation, polarizable and flexible model

Shihao Wang; Natalie M. Cann

2009-06-01T23:59:59.000Z

209

Nanoaggregation and solubility of crude oil asphaltenes from molecular dynamics simulations  

Science Conference Proceedings (OSTI)

The aggregation and solubility of asphaltenes are studied by classical molecular dynamics simulations. Average three-dimensional atomistic models are built on the basis of experimental data for the asphaltenes from a series of crude oil samples. The ... Keywords: Hildebrand, aggregation, asphaltene, forcefield, molecular dynamics, oil, simulation, solubility, solvent

Francesco Frigerio

2009-12-01T23:59:59.000Z

210

Development and Verification of a Computational Fluid Dynamics Model of a Horizontal-Axis Tidal Current Turbine  

SciTech Connect

This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines (HATTs). First, an HATT blade was designed using the blade element momentum method in conjunction with a genetic optimization algorithm. Several unstructured computational grids were generated using this blade geometry and steady CFD simulations were used to perform a grid resolution study. Transient simulations were then performed to determine the effect of time-dependent flow phenomena and the size of the computational timestep on the numerical solution. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.

Lawson, Mi. J.; Li, Y.; Sale, D. C.

2011-01-01T23:59:59.000Z

211

CFD Simulation of Infiltration Heat Recovery  

E-Print Network (OSTI)

Nomenclature Cp= specific heat capacity of air (1006 J/kg K) CP,= specific heat capacity of insulation solidJ/kg K) CPW specific heat capacity of wall sheathing (1200

Buchanan, C.R.

2011-01-01T23:59:59.000Z

212

CFD Simulation of Infiltration Heat Recovery  

E-Print Network (OSTI)

in the outer sheathing (plywood) allow air to leak into thefor turbulence. The plywood sheathing is represented as an

Buchanan, C.R.

2011-01-01T23:59:59.000Z

213

CFD Simulation of Underground Coal Gasification.  

E-Print Network (OSTI)

??Underground Coal Gasification (UCG) is a process in which coal is converted to syngas in-situ. UCG has gained popularity recently as it could be used… (more)

Sarraf Shirazi, Ahad

2012-01-01T23:59:59.000Z

214

Reduced-order, trajectory piecewise-linear models for nonlinear computational fluid dynamics  

E-Print Network (OSTI)

Computational fluid dynamics (CFD) is now widely used throughout the fluid dynamics community and yields accurate models for problems of interest. However, due to its high computational cost, CFD is limited for some ...

Gratton, David, 1979-

2004-01-01T23:59:59.000Z

215

Dynamic simulation of dual-speed wind turbine generation  

SciTech Connect

Induction generators have been used since the early development of utility-scale wind turbine generation. An induction generator is the generator of choice because of its ruggedness, and low cost. With an induction generator, the operating speed of the wind turbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using two induction generators with two different rated speeds. With single- speed operation, the wind turbine operates at different power coefficients (Cp) as the wind speed varies. The operation at maximum Cp can occur only at a single wind speed. However, if the wind speed varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the wind turbine to operate at near maximum Cp over a wider range of wind-speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative to capture more energy than single-speed operation. In this paper, dual-speed operation of a wind turbine will be investigated. One type of control algorithm for dual- speed operation is proposed. Results from a dynamic simulation will be presented to show how the control algorithm works and how power, current and torque of the system vary as the wind turbine is exposed to varying wind speeds.

Muljadi, E.; Butterfield, C.P.

1996-10-01T23:59:59.000Z

216

Dynamic simulation solves process control problem in Oman  

Science Conference Proceedings (OSTI)

A dynamic simulation study solved the process control problems for a Saih Rawl, Oman, gas compressor station operated by Petroleum Development of Oman (PDO). PDO encountered persistent compressor failure that caused frequent facility shutdowns, oil production deferment, and gas flaring. It commissioned MSE (Consultants) Ltd., U.K., to find a solution for the problem. Saih Rawl, about 40 km from Qarn Alam, produces oil and associated gas from a large number of low and high-pressure wells. Oil and gas are separated in three separators. The oil is pumped to Qarn Alam for treatment and export. Associated gas is compressed in two parallel trains. Train K-1115 is a 350,000 standard cu m/day, four-stage reciprocating compressor driven by a fixed-speed electric motor. Train K-1120 is a 1 million standard cu m/day, four-stage reciprocating compressor driven by a fixed-speed electric motor. Train K-1120 is a 1 million standard cu m/day, four-stage centrifugal compressor driven by a variable-speed motor. The paper describes tripping and surging problems with the gas compressor and the control simplifications that solved the problem.

NONE

1998-11-16T23:59:59.000Z

217

A Complexity O(1) priority queue for event driven molecular dynamics simulations  

Science Conference Proceedings (OSTI)

We propose and implement a priority queue suitable for use in event driven molecular dynamics simulations. All operations on the queue take on average O(1) time per collision. In comparison, previously studied queues for event driven molecular dynamics ... Keywords: Molecular dynamics, Priority queue

Gerald Paul

2007-02-01T23:59:59.000Z

218

Understanding Fuming during Metal Refining by CFD  

Science Conference Proceedings (OSTI)

The model accounts for conservation of mass, momentum and energy by the classical ... CFD–Based Modelling on Interfacial Heat Transfer for Water Quenching.

219

Advances in the use of CFD to characterize, design and optimize bioenergy systems  

Science Conference Proceedings (OSTI)

This article is a critical review of the state-of-the-art of computational fluid dynamics (CFD) used to investigate bioreactors that produce biomethane and biohydrogen by means of biochemical conversion technology. First, the issue on rheology of biomaterials ... Keywords: Bioreactor, Computational fluid dynamics, Heat transfer, Light transfer, Mass transfer, Mixing

Binxin Wu

2013-04-01T23:59:59.000Z

220

Dynamic component substitution in web-based simulation  

Science Conference Proceedings (OSTI)

Recent breakthroughs in communication and software engineering has resulted in significant growth of web-based computing. Web-based techniques have been employed for modeling, simulation, and analysis of systems. The models for simulation are usually ...

Dhananjai Madhava Rao; Philip A. Wilsey

2000-12-01T23:59:59.000Z

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


221

Numerical simulations of granular dynamics II. Particle dynamics in a shaken granular material  

E-Print Network (OSTI)

Surfaces of planets and small bodies of our Solar System are often covered by a layer of granular material that can range from a fine regolith to a gravel-like structure of varying depths. Therefore, the dynamics of granular materials are involved in many events occurring during planetary and small-body evolution thus contributing to their geological properties. We demonstrate that the new adaptation of the parallel N-body hard-sphere code pkdgrav has the capability to model accurately the key features of the collective motion of bidisperse granular materials in a dense regime as a result of shaking. As a stringent test of the numerical code we investigate the complex collective ordering and motion of granular material by direct comparison with laboratory experiments. We demonstrate that, as experimentally observed, the scale of the collective motion increases with increasing small-particle additive concentration. We then extend our investigations to assess how self-gravity and external gravity affect collective motion. In our reduced-gravity simulations both the gravitational conditions and the frequency of the vibrations roughly match the conditions on asteroids subjected to seismic shaking, though real regolith is likely to be much more heterogeneous and less ordered than in our idealised simulations. We also show that collective motion can occur in a granular material under a wide range of inter-particle gravity conditions and in the absence of an external gravitational field. These investigations demonstrate the great interest of being able to simulate conditions that are to relevant planetary science yet unreachable by Earth-based laboratory experiments.

Naomi Murdoch; Patrick Michel; Derek C. Richardson; Kerstin Nordstrom; Christian R. Berardi; Simon F. Green; Wolfgang Losert

2013-06-07T23:59:59.000Z

222

Abaqus Simulations of Rock Response to Dynamic Loading  

SciTech Connect

The LANL Geodynamics Team has been applying Abaqus modeling to achieve increasingly complex simulations. Advancements in Abaqus model building and simulation tools allows this progress. We use Lab-developed constitutive models, the fully coupled CEL Abaqus and general contact to simulate response of realistic sites to explosively driven shock.

Steedman, David W. [Los Alamos National Laboratory; Coblentz, David [Los Alamos National Laboratory

2012-08-15T23:59:59.000Z

223

Investigation of combustive flows and dynamic meshing in computational fluid dynamics  

E-Print Network (OSTI)

Computational Fluid Dynamics (CFD) is a ?eld that is constantly advancing. Its advances in terms of capabilities are a result of new theories, faster computers, and new numerical methods. In this thesis, advances in the computational ?uid dynamic modeling of moving bodies and combustive ?ows are investigated. Thus, the basic theory behind CFD is being extended to solve a new class of problems that are generally more complex. The ?rst chapter that investigates some of the results, chapter IV, discusses a technique developed to model unsteady aerodynamics with moving boundaries such as ?apping winged ?ight. This will include mesh deformation and ?uid dynamics theory needed to solve such a complex system. Chapter V will examine the numerical modeling of a combustive ?ow. A three dimensional single vane burner combustion chamber is numerically modeled. Species balance equations along with rates of reactions are introduced when modeling combustive ?ows and these expressions are discussed. A reaction mechanism is validated for use with in situ reheat simulations. Chapter VI compares numerical results with a laminar methane ?ame experiment to further investigate the capabilities of CFD to simulate a combustive ?ow. A new method of examining a combustive ?ow is introduced by looking at the solutions ability to satisfy the second law of thermodynamics. All laminar ?ame simulations are found to be in violation of the entropy inequality.

Chambers, Steven B.

2004-12-01T23:59:59.000Z

224

Designing power system simulators for the smart grid: combining controls, communications, and electro-mechanical dynamics  

Science Conference Proceedings (OSTI)

Open source software has a leading role in research on simulation technology for electrical power systems. Research simulators demonstrate new features for which there is nascent but growing demand not yet provided for by commercial simulators. Of particular interest is the inclusion of models of software-intensive and communication-intensive controls in simulations of power system transients. This paper describes two features of the ORNL power system simulator that help it meet this need. First is its use of discrete event simulation for all aspects of the model: control, communication, and electro-mechanical dynamics. Second is an interoperability interface that enables the ORNL power system simulator to be integrated with existing, discrete event simulators of digital communication systems. The paper concludes with a brief discussion of how these aspects of the ORNL power system simulator might be inserted into production-grade simulation tools.

Nutaro, James J [ORNL

2011-01-01T23:59:59.000Z

225

I12: Quantum Chemical Molecular Dynamics Simulations on ...  

Science Conference Proceedings (OSTI)

To achieve the fabrication with less defects, the dynamic behaviors of ions and radicals with chemical reactions should be clarified. Then, we investigate the ...

226

Simulation of Rising Bubbles Dynamics Using the Lattice Boltzmann Method.  

E-Print Network (OSTI)

?? The main purpose of this thesis was to propose and test a new approach that captures the features of single and multiple bubbles dynamics… (more)

Ngachin, Merlin

2011-01-01T23:59:59.000Z

227

A Simulation-based Study of TCP Dynamics  

Science Conference Proceedings (OSTI)

... End Internet Dynamics", Ph.D. Thesis, LBNL-40319, UCB//CSD-97-945, University of California, Berkley. [20] WR Stevens ...

2009-02-03T23:59:59.000Z

228

Issues in computational fluid dynamics code verification and validation  

SciTech Connect

A broad range of mathematical modeling errors of fluid flow physics and numerical approximation errors are addressed in computational fluid dynamics (CFD). It is strongly believed that if CFD is to have a major impact on the design of engineering hardware and flight systems, the level of confidence in complex simulations must substantially improve. To better understand the present limitations of CFD simulations, a wide variety of physical modeling, discretization, and solution errors are identified and discussed. Here, discretization and solution errors refer to all errors caused by conversion of the original partial differential, or integral, conservation equations representing the physical process, to algebraic equations and their solution on a computer. The impact of boundary conditions on the solution of the partial differential equations and their discrete representation will also be discussed. Throughout the article, clear distinctions are made between the analytical mathematical models of fluid dynamics and the numerical models. Lax`s Equivalence Theorem and its frailties in practical CFD solutions are pointed out. Distinctions are also made between the existence and uniqueness of solutions to the partial differential equations as opposed to the discrete equations. Two techniques are briefly discussed for the detection and quantification of certain types of discretization and grid resolution errors.

Oberkampf, W.L.; Blottner, F.G.

1997-09-01T23:59:59.000Z

229

Performance analysis and optimization of molecular dynamics simulation on Godson-T many-core processor  

Science Conference Proceedings (OSTI)

Molecular dynamics (MD) simulation has broad applications, but its irregular memory-access pattern makes performance optimization a challenge. This paper presents a joint application/architecture study to enhance on-chip parallelism of MD on Godson-T ...

Liu Peng; Aiichiro Nakano; Guangming Tan; Priya Vashishta; Dongrui Fan; Hao Zhang; Rajiv K. Kalia; Fenglong Song

2011-05-01T23:59:59.000Z

230

Qualitative simulation and related approaches for the analysis of dynamic systems  

Science Conference Proceedings (OSTI)

Methods for qualitative simulation allow predictions on the dynamics of a system to be made in the absence of quantitative information, by inferring the range of possible qualitative behaviors compatible with the structure of the system. This article ...

Hidde De Jong

2004-06-01T23:59:59.000Z

231

The Dynamics of an Explosively Developing Cyclone Simulated by a General Circulation Model  

Science Conference Proceedings (OSTI)

The synoptic structure and dynamics of an explosively developing winter extratropical cyclone simulated by NCAR’s CCM2 general circulation model is examined and compared with cyclones that have developed explosively in nature. The primary ...

Karen D. Walthorn; Phillip J. Smith

1998-11-01T23:59:59.000Z

232

A molecular dynamics simulation study of elastic properties of HMX Thomas D. Sewell and Ralph Menikoff  

E-Print Network (OSTI)

. (1989a,b) from a molecular dynamics simulation of the measured structure factor results of Susman et al., and BOLLER,A.,1994, Thermochim. Acta, 238, 227. ZHANG,M., and BOOLCHAND,P.,1994, Science, 266, 1355. 1772

Utah, University of

233

The Effects of Different Climate Input Datasets on Simulated Carbon Dynamics in the Western Arctic  

Science Conference Proceedings (OSTI)

As part of the Western Arctic Linkage Experiment (WALE), simulations of carbon dynamics in the western Arctic (WALE region) were conducted during two recent decades by driving the Terrestrial Ecosystem Model (TEM) with three alternative climate ...

Joy Clein; A. David McGuire; Eugenie S. Euskirchen; Monika Calef

2007-08-01T23:59:59.000Z

234

Transforming molecular biology research through extreme acceleration of AMBER molecular dynamics simulations: sampling for the 99%  

Science Conference Proceedings (OSTI)

This talk will cover recent developments in the acceleration of Molecular Dynamics Simulations using NVIDIA Graphics Processing units with the AMBER software package. In particular it will focus on recent algorithmic improvements aimed at accelerating ...

Ross C. Walker; Levi Pierce; Romelia Salomon

2012-07-01T23:59:59.000Z

235

Simulations of Dynamics and Transport during the September 2002 Antarctic Major Warming  

Science Conference Proceedings (OSTI)

A mechanistic model simulation initialized on 14 September 2002, forced by 100-hPa geopotential heights from Met Office analyses, reproduced the dynamical features of the 2002 Antarctic major warming. The vortex split on 25 September; recovery ...

Gloria L. Manney; Joseph L. Sabutis; Douglas R. Allen; William A. Lahoz; Adam A. Scaife; Cora E. Randall; Steven Pawson; Barbara Naujokat; Richard Swinbank

2005-03-01T23:59:59.000Z

236

Molecular dynamics simulation of hydrogen diffusion in titanium  

National Nuclear Security Administration (NNSA)

of hydrogen-metal systems for absorption of nuclear radiation, in neutron sources, for storage of hydrogen, or as catalyzers. This work is devoted to atomistic simulation of...

237

Simulation of the heat exchangers dynamics in MATLAB&simulink  

Science Conference Proceedings (OSTI)

Heat exchangers that transfer energy from flue gas to steam are important units of thermal power stations. Their inertias are often decisive for the design of the steam temperature control system. In this paper, the analysis and the simulation of the ... Keywords: MATLAB&simulink, S-functions, finite difference method, heat exchangers, partial differential equations, real-time, simulation, superheaters

Pavel Nevriva; Stepan Ozana; Ladislav Vilimec

2009-10-01T23:59:59.000Z

238

Simulating Collisions for Hydrokinetic Turbines. FY2010 Annual Progress Report.  

DOE Green Energy (OSTI)

Computational fluid dynamics (CFD) simulations of turbulent flow and particle motion are being conducted to evaluate the frequency and severity of collisions between marine and hydrokinetic (MHK) energy devices and debris or aquatic organisms. The work is part of a collaborative research project between Pacific Northwest National Laboratory (PNNL) and Sandia National Laboratories , funded by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Wind and Water Power Program. During FY2010 a reference design for an axial flow MHK turbine was used to develop a computational geometry for inclusion into a CFD model. Unsteady simulations of turbulent flow and the moving MHK turbine blades are being performed and the results used for simulation of particle trajectories. Preliminary results and plans for future work are presented.

Richmond, Marshall C.; Rakowski, Cynthia L.; Perkins, William A.; Serkowski, John A.

2010-11-30T23:59:59.000Z

239

Recent CFD-Related Activities at the High  

E-Print Network (OSTI)

· early CFD activities at HFIR · cold-source (and other upgrades)CFD activities at HFIR · LEU Conversion this then at a research reactor ? · 1991 started at HFIR · 1992 graduation · ~ 2003 COMSOL becomes the tool of choice (Freels) Early CFD Activities at HFIR #12;Freels ,CFD Colloquium at UTK,in honor of A, J. Baker, 05

Tennessee, University of

240

The dynamic simulation of organic farming development scenarios - A case study in Slovenia  

Science Conference Proceedings (OSTI)

In this paper a system dynamics model for organic farming development to support government decision making is presented. The system incorporates relevant variables which affect organic farming development. The user seeks answers to strategic questions ... Keywords: Model, Organic farming, Simulation, System dynamics

Rtomir Rozman, Karmen Paek, Miroljub Kljaji?, Martina Bavec, Jernej Turk, Franc Bavec, Davorin Kofja?, Andrej ŠKraba

2013-08-01T23:59:59.000Z

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


241

Using system dynamics for simulation and optimization of one coal industry system under fuzzy environment  

Science Conference Proceedings (OSTI)

In this paper, we have developed a model that integrates system dynamics with fuzzy multiple objective programming (SD-FMOP). This model can be used to study the complex interactions in a industry system. In the process of confirming sensitive parameters ... Keywords: Coal industry planning, Fuzzy set theory, Multiple objective programming, Simulation, System dynamics

Jiuping Xu; Xiaofei Li

2011-09-01T23:59:59.000Z

242

Dynamical Subgrid-Scale Parameterizations from Direct Numerical Simulations  

Science Conference Proceedings (OSTI)

Dynamical subgrid-scale parameterizations of stochastic backscatter, eddy drain viscosity, and net eddy viscosity have been formulated and calculated for two-dimensional turbulent flows on the sphere based on the statistics of direct numerical ...

Jorgen S. Frederiksen; Steven M. Kepert

2006-11-01T23:59:59.000Z

243

ADAPT: abstraction hierarchies to better simulate teamwork under dynamics  

Science Conference Proceedings (OSTI)

In this paper we present a lightweight teamwork implementation by using abstraction hierarchies. The basis of this implementation is ADAPT, which supports Autonomous Dynamic Agent Planning for Teamwork. ADAPT's novelty ...

Meirav Hadad; Avi Rosenfeld

2011-05-01T23:59:59.000Z

244

AMIP Simulation with the CAM4 Spectral Element Dynamical Core  

Science Conference Proceedings (OSTI)

The authors evaluate the climate produced by the Community Climate System Model, version 4, running with the new spectral element atmospheric dynamical core option. The spectral element method is configured to use a cubed-sphere grid, providing ...

K. J. Evans; P. H. Lauritzen; S. K. Mishra; R. B. Neale; M. A. Taylor; J. J. Tribbia

2013-02-01T23:59:59.000Z

245

Numerical Simulation of the Flow Field in 3D Eccentric Annular and 2D Centered Labyrinth Seals for Comparison with Experimental LDA Data  

E-Print Network (OSTI)

The flow field in an annular seal is simulated for synchronous circular whirl orbits with 60Hz whirl frequency and a clearance/radius ratio of 0.0154 using the Fluent Computational Fluid Dynamics (CFD) code. Fluent's Moving Reference Frame model (MRF) is used to render the flow quasi-steady by making transformations to a rotating frame. The computed flow fields for velocity, pressure and shear stress measurements are compared with the experimental data of Winslow, Thames and Cusano. The CFD predictions are found to be in good agreement with the experimental results. The present CFD methodology can be extended to other whirl frequencies and clearances. The dynamic wall pressure distributions in an annular seal for non-circular whirl orbits were obtained using CFD. The simulations were performed using a time dependant solver utilizing Fluent's Dynamic Mesh model and User Defined Functions (UDFs). The wall pressure distributions obtained from the simulations are compared with data of Cusano. The CFD simulations over predicted the pressure field when compared to experimental results however the general trends in pressure contours are similar. The flow fields for varying rotor eccentricities are also studied by performing coordinate transformations and rendering the flow quasi-steady at set eccentricities using Fluent's MRF model. The computed velocity and pressure fields are compared with the time dependant solution obtained using Fluent's Dynamic Mesh model and UDFs for the same eccentricity. Good agreement in the velocity fields is obtained; however the pressure fields require further investigation. 2D Labyrinth seal simulations were performed for comparisons with experimental LDA data from Johnson. The velocity fields match the experimental LDA data to a fair degree of extent; however, Fluent simulations under predicted the secondary recirculation zones in Labyrinth Backward Swirl (LBS) case.

Vijaykumar, Anand

2010-12-01T23:59:59.000Z

246

Dynamic Simulation of Lightning Attachment to Earthed Overhead Transmission Line Structures  

Science Conference Proceedings (OSTI)

In this paper a novel method is presented to investigate lightning stroke attachment to earthed overhead transmission line structures. This method is based on the dynamic simulation of lightning downward leader movement toward the ground in three dimensions. ... Keywords: charge simulation method, downward leader, lightning, transmission line, upward leader

Mohammad Reza Bank Tavakoli; Behrooz Vahidi

2010-07-01T23:59:59.000Z

247

A simulation-and-regression approach for stochastic dynamic programs with endogenous state variables  

Science Conference Proceedings (OSTI)

We investigate the optimum control of a stochastic system, in the presence of both exogenous (control-independent) stochastic state variables and endogenous (control-dependent) state variables. Our solution approach relies on simulations and regressions ... Keywords: Approximate dynamic programming, Hydropower management, Least-squares Monte Carlo, Simulation and regression, Stochastic control

Michel Denault, Jean-Guy Simonato, Lars Stentoft

2013-11-01T23:59:59.000Z

248

Multilevel Task Partition Algorithm for Parallel Simulation of Power System Dynamics  

Science Conference Proceedings (OSTI)

Nowadays task partition for parallel computing is becoming more and more important. Particular in power system dynamic simulation, it is critical to design an efficient partition algorithm to reduce the communication and balance the computation load ... Keywords: graph partition, parallel simulation, power system, task partition

Wei Xue; Shanxiang Qi

2007-05-01T23:59:59.000Z

249

Time-stepping numerical simulation of switched circuits within the nonsmooth dynamical systems approach  

Science Conference Proceedings (OSTI)

The numerical integration of switching circuits is known to be a tough issue when the number of switches is large, or when sliding modes exist. Then, classical analog simulators may behave poorly, or even fail. In this paper, it is shown on two examples ... Keywords: analog simulation, backward Euler algorithm, complementarity dynamical systems, complementarity problems, multivalued systems, power converters, switching circuits, unilateral state constraints

Vincent Acary; Olivier Bonnefon; Bernard Brogliato

2010-07-01T23:59:59.000Z

250

Dynamical Influences of Anvil Shading on Simulated Supercell Thunderstorms  

Science Conference Proceedings (OSTI)

Numerical simulations of supercell thunderstorms including parameterized radiative transfer and surface fluxes are performed using the Advanced Regional Prediction System (ARPS) model to investigate how low-level air temperature deficits within ...

Jeffrey Frame; Paul Markowski

2013-08-01T23:59:59.000Z

251

Dynamic Downscaling of Seasonal Simulations over South America  

Science Conference Proceedings (OSTI)

In this paper multiple atmospheric global circulation model (AGCM) integrations at T42 spectral truncation and prescribed sea surface temperature were used to drive regional spectral model (RSM) simulations at 80-km resolution for the austral ...

Vasubandhu Misra; Paul A. Dirmeyer; Ben P. Kirtman

2003-01-01T23:59:59.000Z

252

Solar Pilot Plant, Phase I. Preliminary design report. Volume II, Book 3. Dynamic simulation model and computer program descriptions. CDRL item 2. [SPP dynamics simulation program  

DOE Green Energy (OSTI)

The mathematical models and computer program comprising the SPP Dynamic Simulation are described. The SPP Dynamic Simulation is a computerized model representing the time-varying performance characteristics of the SPP. The model incorporates all the principal components of the pilot plant. Time-dependent direct normal solar insulation, as corrupted by simulated cloud passages, is transformed into absorbed radiant power by actions of the heliostat field and enclosed receiver cavity. The absorbed power then drives the steam generator model to produce superheated steam for the turbine and/or thermal storage subsystems. The thermal storage subsystem can, in turn, also produce steam for the turbine. The turbine using the steam flow energy produces the mechanical shaft power necessary for the generator to convert it to electrical power. This electrical power is subsequently transmitted to a transmission grid system. Exhaust steam from the turbine is condensed, reheated, deaerated, and pressurized by pumps for return as feedwater to the thermal storage and/or steam generator. A master control/instrumentation system is utilized to coordinate the various plant operations. The master controller reacts to plant operator demands and control settings to effect the desired output response. The SPP Dynamic Simulation Computer program is written in FORTRAN language. Various input options (e.g., insolation values, load demands, initial pressures/temperatures/flows) are permitted. Plant performance may be monitored via computer printout or computer generated plots. The remainder of this document describes the detailed pilot plant dynamic model, the basis for this simulation, and the utilization of this simulation to obtain analytical plant performance results.

None

1977-05-01T23:59:59.000Z

253

Order parameter prediction from molecular dynamics simulations in proteins  

E-Print Network (OSTI)

A molecular understanding of how protein function is related to protein structure will require an ability to understand large conformational changes between multiple states. Unfortunately these states are often separated by high free energy barriers and within a complex energy landscape. This makes it very difficult to reliably connect, for example by all-atom molecular dynamics calculations, the states, their energies and the pathways between them. A major issue needed to improve sampling on the intermediate states is an order parameter -- a reduced descriptor for the major subset of degrees of freedom -- that can be used to aid sampling for the large conformational change. We present a novel way to combine information from molecular dynamics using non-linear time series and dimensionality reduction, in order to quantitatively determine an order parameter connecting two large-scale conformationally distinct protein states. This new method suggests an implementation for molecular dynamics calculations that ma...

Perilla, Juan R

2011-01-01T23:59:59.000Z

254

AMIP Simulation with the CAM4 Spectral Element Dynamical Core  

SciTech Connect

We evaluate the climate produced by the Community Earth System Model, version 1, running with the new spectral-element atmospheric dynamical core option. The spectral-element method is congured to use a cubed-sphere grid, providing quasi-uniform resolution over the sphere, increased parallel scalability and removing the need for polar filters. It uses a fourth order accurate spatial discretization which locally conserves mass and moist total energy. Using the Atmosphere Model Intercomparison Project protocol, we compare the results from the spectral-element dy- namical core with those produced by the default nite-volume dynamical core and with observations.

Evans, Katherine J [ORNL; Lauritzen, Peter [National Center for Atmospheric Research (NCAR); Mishra, Saroj [National Center for Atmospheric Research (NCAR); Neale, Rich [National Center for Atmospheric Research (NCAR); Taylor, Mark [Sandia National Laboratories (SNL); Tribbia, Joe [National Center for Atmospheric Research (NCAR)

2013-01-01T23:59:59.000Z

255

Dynamic Human Reliability Analysis: Benefits and Challenges of Simulating Human Performance  

Science Conference Proceedings (OSTI)

To date, there has been considerable work on dynamic event trees and other areas related to dynamic probabilistic safety assessment (PSA). The counterpart to these efforts in human reliability analysis (HRA) has centered on the development of specific methods to account for the dynamic nature of human performance. In this paper, the author posits that the key to dynamic HRA is not in the development of specific methods but in the utilization of cognitive modeling and simulation to produce a framework of data that may be used in quantifying the likelihood of human error. This paper provides an overview of simulation approaches to HRA; reviews differences between first, second, and dynamic generation HRA; and outlines potential benefits and challenges of this approach.

R. L. Boring

2007-06-01T23:59:59.000Z

256

Extended Lagrangian quantum molecular dynamics simulations of shock-induced chemistry in hydrocarbons  

SciTech Connect

A set of interatomic potentials for hydrocarbons that are based upon the self-consistent charge transfer tight-binding approximation to density functional theory have been developed and implemented into the quantum molecular dynamics code ''LATTE''. The interatomic potentials exhibit an outstanding level of transferability and have been applied in molecular dynamics simulations of tert-butylacetylene under thermodynamic conditions that correspond to its single-shock Hugoniot. We have achieved precise conservation of the total energy during microcanonical molecular dynamics trajectories under incomplete convergence via the extended Lagrangian Born-Oppenheimer molecular dynamics formalism. In good agreement with the results of a series of flyer-plate impact experiments, our SCC-TB molecular dynamics simulations show that tert-butylactylene molecules polymerize at shock pressures around 6.1 GPa.

Sanville, Edward J [Los Alamos National Laboratory; Bock, Nicolas [Los Alamos National Laboratory; Challacombe, William M [Los Alamos National Laboratory; Cawkwell, Marc J [Los Alamos National Laboratory; Niklasson, Anders M N [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Stephen [Los Alamos National Laboratory; Sewell, Thomas D [UNIV OF MISSOURI

2010-01-01T23:59:59.000Z

257

Adaptive Construction Modelling Within Whole Building Dynamic Simulation  

E-Print Network (OSTI)

............................ vii List of Symbols .......................... ix Chapter 1: Introduction ....................... 1 1.1 The need for building energy simulation ............... 1 1.2 The evolution of building energy simulation tools ............ 2 1.3 The need for accurate building fabric modelling ............ 4 1.4 Objective and outline of the present work ............... 5 Chapter 2: Review of Heat and Moisture Transport within Building Materials ...... 8 2.1 Building energy simulation ................... 8 2.1.1 Heat conduction .................... 8 2.1.2 Mass diffusion .................... 16 2.2 Adaptive gridding ...................... 18 2.3 Thermophysical properties ................... 23 2.4 Combined heat and moisture transport ................ 27 2.4.1 Moisture transport in porous building materials .......... 29 2.4.2 Differential equations for combined heat and moisture transport ..... 33 Chapter 3: Adaptive Building Fabric Gridding ................ 37 3.1 Math...

Abdullatif Nakhi Degree; Abdullatif E. Nakhi; Wife Masoumah

1995-01-01T23:59:59.000Z

258

System dynamics model for simulation of the software inspection process  

Science Conference Proceedings (OSTI)

Repairing a defect in the late phases of software development can be a hundred times more expensive than finding and fixing it during the requirements and design phase. Software inspection is a technique that may be used to aid in the identification ... Keywords: defect detection, software inspection, system dynamics

Jailton Jr. De Sousa Coelho, José Luis Braga, Bernardo Giori Ambrósio

2013-08-01T23:59:59.000Z

259

Numerical aspects in the dynamic simulation of geometrically exact rods  

Science Conference Proceedings (OSTI)

Classical geometrically exact Kirchhoff and Cosserat models are used to study the nonlinear deformation of rods. Extension, bending and torsion of the rod may be represented by the Kirchhoff model. The Cosserat model additionally takes into account shearing ... Keywords: Deformable bodies, Geometrically exact rods, Kirchhoff and Cosserat rods, Method of lines, Multibody dynamics, Partial differential algebraic equations, Time integration

Holger Lang; Martin Arnold

2012-10-01T23:59:59.000Z

260

CFD analysis of the effect of elbow radius on pressure drop in multiphase flow  

Science Conference Proceedings (OSTI)

Computational fluid dynamics (CFD) analysis was performed in four different 90 degree elbows with air-water two-phase flows. The inside diameters of the elbows were 6.35mm and 12.7mm with radius to diameter ratios (r/D) of 1.5 to 3. The pressure drops ...

Quamrul H. Mazumder

2012-01-01T23:59:59.000Z

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


261

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

Science Conference Proceedings (OSTI)

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

2013-07-24T23:59:59.000Z

262

Simulation of Dryline Misovortex Dynamics and Cumulus Formation  

Science Conference Proceedings (OSTI)

A dryline and misocyclones have been simulated in a cloud-resolving model by applying specified initial and time-dependent lateral boundary conditions obtained from analyses of the 22 May 2002 International H2O Project (IHOP_2002) dataset. The ...

Michael S. Buban; Conrad L. Ziegler; Edward R. Mansell; Yvette P. Richardson

2012-11-01T23:59:59.000Z

263

System dynamics simulation of the expansion of the Panama Canal  

Science Conference Proceedings (OSTI)

The expansion of the Panama Canal could be the largest project attempted by the Republic of Panama in its 100 years of existence. The objective of this simulation study is to use the Canal Expansion project to develop and demonstrate how more precise ...

Humberto R. Alvarez A.; Dario Solis; Arnoldo R. Cano S.; Serge Sala-Diakanda

2006-12-01T23:59:59.000Z

264

Stochastic Simulation of Nonadiabatic Dynamics at Long Time  

E-Print Network (OSTI)

Using a generalized energy-conserving transition probability, it is shown how nonadiabatic calculations, within the Wigner-Heisenberg representation of quantum mechanics, can be reliably extended to far longer times than those allowed by a primitive sampling scheme. Tackling the spin-boson model as a paradigmatic example, substantial numerical evidence is provided that effective integration of the dynamics can be achieved for a wide range of temperatures and friction.

Uken, Daniel A; Petruccione, Francesco

2010-01-01T23:59:59.000Z

265

Stochastic Simulation of Nonadiabatic Dynamics at Long Time  

E-Print Network (OSTI)

Using a generalized energy-conserving transition probability, it is shown how nonadiabatic calculations, within the Wigner-Heisenberg representation of quantum mechanics, can be reliably extended to far longer times than those allowed by a primitive sampling scheme. Tackling the spin-boson model as a paradigmatic example, substantial numerical evidence is provided that effective integration of the dynamics can be achieved for a wide range of temperatures and friction.

Daniel A. Uken; Alessandro Sergi; Francesco Petruccione

2010-03-16T23:59:59.000Z

266

Darlington tritium removal facility and station upgrading plant dynamic process simulation  

SciTech Connect

Ontario Power Generation Nuclear (OPGN) has a 4 x 880 MWe CANDU nuclear station at its Darlington Nuclear Div. located in Bowmanville. The station has been operating a Tritium Removal Facility (TRF) and a D{sub 2}O station Upgrading Plant (SUP) since 1989. Both facilities were designed with a Distributed Control System (DCS) and programmable logic controllers (PLC) for process control. This control system was replaced with a DCS only, in 1998. A dynamic plant simulator was developed for the Darlington TRF (DTRF) and the SUP, as part of the computer control system replacement. The simulator was used to test the new software, required to eliminate the PLCs. The simulator is now used for operator training and testing of process control software changes prior to field installation. Dynamic simulation will be essential for the ITER isotope separation system, where the process is more dynamic than the relatively steady-state DTRF process. This paper describes the development and application of the DTRF and SUP dynamic simulator, its benefits, architecture, and the operational experience with the simulator. (authors)

Busigin, A. [NITEK USA, Inc., 6405 NW 77 PL, Parkland, FL 33067 (United States); Williams, G. I. D.; Wong, T. C. W.; Kulczynski, D.; Reid, A. [Ontario Power Generation Nuclear, Box 4000, Bowmanville, ON L1C 3Z8 (Canada)

2008-07-15T23:59:59.000Z

267

The optimizing-simulator: merging simulation and optimization using approximate dynamic programming  

Science Conference Proceedings (OSTI)

There is a wide range of simulation problems that involve making decisions during the simulation, where we would like to make the best decisions possible, taking into account not only what we know when we make the decision, but also the impact of the ...

Warren B. Powell

2007-12-01T23:59:59.000Z

268

Real-time dynamic simulator for the Topaz II reactor power system  

SciTech Connect

A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator is a self-contained IBM-PC compatible based system that executes at a speed faster than real-time. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulation of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and causality conditions.

Kwok, K.S.

1994-10-01T23:59:59.000Z

269

11/11/2002 1AVS 49th Int'l Symp. MS-MoA7 (Oct. 29, 2002) -Cho Dynamic Simulation and Optimization  

E-Print Network (OSTI)

'l Symp. MS-MoA7 (Oct. 29, 2002) - Cho Scope & Strategy Multilevel modeling & simulation incorporating dynamics &Multilevel modeling & simulation incorporating dynamics & stochasticsstochastics ESH fluctuations Incorporate capability in models for dynamics & stochastics Process & tool Fundamental science Si

Rubloff, Gary W.

270

Molecular dynamics simulations of the interaction of glucose with imidazole in aqueous solution  

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

Molecular dynamics simulations of the interaction of glucose with imidazole in Molecular dynamics simulations of the interaction of glucose with imidazole in aqueous solution Mo Chen, Yannick J. Bomble, Michael E. Himmel, John W. Brady PII: S0008-6215(11)00592-1 DOI: 10.1016/j.carres.2011.12.008 Reference: CAR 6026 To appear in: Carbohydrate Research Received Date: 15 June 2011 Revised Date: 22 November 2011 Accepted Date: 8 December 2011 Please cite this article as: Chen, M., Bomble, Y.J., Himmel, M.E., Brady, J.W., Molecular dynamics simulations of the interaction of glucose with imidazole in aqueous solution, Carbohydrate Research (2011), doi: 10.1016/j.carres. 2011.12.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and

271

Molecular dynamics simulation of strongly coupled QCD plasmas  

E-Print Network (OSTI)

The properties of a strongly interacting quark plasma are investigated by molecular dynamics method including non-abelian quark-quark potential. Our main goal is to study the thermalization process in this system. We find an interesting resonance-like behaviour: at a characteristic time close to the inverse plasma frequency the quark plasma is heated up substantially via energy transfer from quark potential energy into one particle kinetic energy. Color rotation mechanism enhances the effectivity of this heating process, leading to a very fast thermalization with high temperature.

P. Hartmann; Z. Donko; P. Levai; G. J. Kalman

2006-01-06T23:59:59.000Z

272

Long-time protein folding dynamics from short-time molecular dynamics simulations  

E-Print Network (OSTI)

histogram analysis method (WHAM) [25, 8] and is shown inexchange simulation by WHAM with corresponding uncertaintiesat 302K, as determined by WHAM, and assigning ini- tial

Chodera, J D; Swope, W C; Pitera, J W; Dill, Ken A

2006-01-01T23:59:59.000Z

273

Development of CFD models to support LEU Conversion of ORNL s High Flux Isotope Reactor  

SciTech Connect

The US Department of Energy s National Nuclear Security Administration (NNSA) is participating in the Global Threat Reduction Initiative to reduce and protect vulnerable nuclear and radiological materials located at civilian sites worldwide. As an integral part of one of NNSA s subprograms, Reduced Enrichment for Research and Test Reactors, HFIR is being converted from the present HEU core to a low enriched uranium (LEU) core with less than 20% of U-235 by weight. Because of HFIR s importance for condensed matter research in the United States, its conversion to a high-density, U-Mo-based, LEU fuel should not significantly impact its existing performance. Furthermore, cost and availability considerations suggest making only minimal changes to the overall HFIR facility. Therefore, the goal of this conversion program is only to substitute LEU for the fuel type in the existing fuel plate design, retaining the same number of fuel plates, with the same physical dimensions, as in the current HFIR HEU core. Because LEU-specific testing and experiments will be limited, COMSOL Multiphysics was chosen to provide the needed simulation capability to validate against the HEU design data and previous calculations, and predict the performance of the proposed LEU fuel for design and safety analyses. To achieve it, advanced COMSOL-based multiphysics simulations, including computational fluid dynamics (CFD), are being developed to capture the turbulent flows and associated heat transfer in fine detail and to improve predictive accuracy [2].

Khane, Vaibhav B [ORNL; Jain, Prashant K [ORNL; Freels, James D [ORNL

2012-01-01T23:59:59.000Z

274

Design studies for the transmission simulator method of experimental dynamic substructuring.  

SciTech Connect

In recent years, a successful method for generating experimental dynamic substructures has been developed using an instrumented fixture, the transmission simulator. The transmission simulator method solves many of the problems associated with experimental substructuring. These solutions effectively address: (1) rotation and moment estimation at connection points; (2) providing substructure Ritz vectors that adequately span the connection motion space; and (3) adequately addressing multiple and continuous attachment locations. However, the transmission simulator method may fail if the transmission simulator is poorly designed. Four areas of the design addressed here are: (1) designating response sensor locations; (2) designating force input locations; (3) physical design of the transmission simulator; and (4) modal test design. In addition to the transmission simulator design investigations, a review of the theory with an example problem is presented.

Mayes, Randall Lee; Arviso, Michael

2010-05-01T23:59:59.000Z

275

Molecular dynamics simulation of high strain-rate void nucleation and growth in copper  

Science Conference Proceedings (OSTI)

Isotropic tension is simulated in nanoscale polycrystalline copper with 10 nm grain size using large-scale molecular dynamics. The nanocrystalline copper is fabricated on the computer by growing randomly oriented grains from seed sites in simulations cell. Constant volume strain rates of 10-8 to 10-10 are considered for systems ranging from 10-5 to 10-6 atoms using EAM interatomic potential for copper. The spacing between voids for room temperature single crystal simulations is found to scale approximately as l{approximately}0. 005 Cs/gamma, where Cs is the sound speed and gamma is the strain rate. Below strain rates of about 10-9, only one void is observed to nucleate and grow in the 10 nm polycrystalline simulation cell. The growth of small voids is simulated by cutting a void out of the simulation cell and repeating the isotropic expansion.

Belak, J.

1997-07-01T23:59:59.000Z

276

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

Science Conference Proceedings (OSTI)

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

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

2011-10-01T23:59:59.000Z

277

Low Wind Speed Technology Phase II: Offshore Floating Wind Turbine Concepts: Fully Coupled Dynamic Response Simulations; Massachusetts Institute of Technology  

SciTech Connect

This fact sheet describes a subcontract with Massachusetts Institute of Technology to study dynamic response simulations to evaluate floating platform concepts for offshore wind turbines.

2006-03-01T23:59:59.000Z

278

Langevin dynamics simulations of biomolecules on graphics processors  

E-Print Network (OSTI)

Due to the very long timescales involved (us-s), theoretical modeling of fundamental biological processes including folding, misfolding, and mechanical unraveling of biomolecules, under physiologically relevant conditions, is challenging even for distributed computing systems. Graphics Processing Units (GPUs) are emerging as an alternative programming platform to the more traditional CPUs as they provide high raw computational power that can be utilized in a wide range of scientific applications. Using a coarse-grained Self Organized Polymer (SOP) model, we have developed and tested the GPU-based implementation of Langevin simulations for proteins (SOP-GPU program). Simultaneous calculation of forces for all particles is implemented using either the particle based or the interacting pair based parallelization, which leads to a ~30-fold acceleration compared to an optimized CPU version of the program. We assess the computational performance of an end-to-end application of the SOP-GPU program, where all steps of the algorithm are running on the GPU, by profiling the associated simulation time and memory usage for a number of small proteins, long protein fibers, and large-size protein assemblies. The SOP-GPU package can now be used in the theoretical exploration of the mechanical properties of large-size protein systems to generate the force-extension and force-indentation profiles under the experimental conditions of force application, and to relate the results of single-molecule experiments in vitro and in silico.

A. Zhmurov; R. I. Dima; Y. Kholodov; V. Barsegov

2010-03-04T23:59:59.000Z

279

Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)  

SciTech Connect

The Nuclear Energy Computational Fluid Dynamics Advanced Modeling and Simulation (NE-CAMS) system is being developed at the Idaho National Laboratory (INL) in collaboration with Bettis Laboratory, Sandia National Laboratory (SNL), Argonne National Laboratory (ANL), Utah State University (USU), and other interested parties with the objective of developing and implementing a comprehensive and readily accessible data and information management system for computational fluid dynamics (CFD) verification and validation (V&V) in support of nuclear energy systems design and safety analysis. The two key objectives of the NE-CAMS effort are to identify, collect, assess, store and maintain high resolution and high quality experimental data and related expert knowledge (metadata) for use in CFD V&V assessments specific to the nuclear energy field and to establish a working relationship with the U.S. Nuclear Regulatory Commission (NRC) to develop a CFD V&V database, including benchmark cases, that addresses and supports the associated NRC regulations and policies on the use of CFD analysis. In particular, the NE-CAMS system will support the Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program, which aims to develop and deploy advanced modeling and simulation methods and computational tools for reliable numerical simulation of nuclear reactor systems for design and safety analysis. Primary NE-CAMS Elements There are four primary elements of the NE-CAMS knowledge base designed to support computer modeling and simulation in the nuclear energy arena as listed below. Element 1. The database will contain experimental data that can be used for CFD validation that is relevant to nuclear reactor and plant processes, particularly those important to the nuclear industry and the NRC. Element 2. Qualification standards for data evaluation and classification will be incorporated and applied such that validation data sets will result in well-defined, well-characterized data. Element 3. Standards will be established for the design and operation of experiments for the generation of new validation data sets that are to be submitted to NE-CAMS that addresses the completeness and characterization of the dataset. Element 4. Standards will be developed for performing verification and validation (V&V) to establish confidence levels in CFD analyses of nuclear reactor processes; such processes will be acceptable and recognized by both CFD experts and the NRC.

Kimberlyn C. Mousseau

2011-10-01T23:59:59.000Z

280

Simulation studies of ion dynamic effects on dense plasma line shapes  

DOE Green Energy (OSTI)

Computer simulations have been widely used in studying dense plasma properties including the local field properties important in spectral line broadening calculations. We will review here a more recent use of simulation, possibly less familiar to this audience, where the time dependent ionic microfield generated by computer simulation of a plasma is used directly as a time dependent external potential for the evolution of the electronic structure of an ion. This permits calculation of the dipole correlation function and thus line shapes with the inclusion of ion dynamic effects. 12 refs., 7 figs.

Pollock, E.L.

1986-12-01T23:59:59.000Z

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


281

Molecular dynamics simulation of UO2 nanocrystals melting  

E-Print Network (OSTI)

In this article we study melting of uranium dioxide (UO2) nanocrystals (NC) isolated in vacuum (i.e. non-periodic boundary conditions) using molecular dynamics (MD) in the approximation of pair potentials and rigid ions. We calculate the size dependence of the temperature and heat of melting, the density jump for crystals of cubic shape and volumes up to 1000 nm^3 (50000 particles). Linear and parabolic extrapolations of these dependences to macroscopic (infinite) size are considered, the parabolic is found to be better suited for the analysis of data on the temperature and the heat of melting. The closest to the modern experimental data estimates of the melting temperature of macrocrystals are obtained using the interaction potentials Goel-08 (2969K), Yakub-09 (3105K) and MOX-07 (3291K). The density jump at melting is well reproduced by Yakub-09 (8.66%) and MOX-07 (7.97%). The heat of fusion for all sets of the potentials considered is found to be underestimated by 50-75%, possibly because of the excluded he...

Boyarchenkov, A S; Nekrasov, K A; Kupryazhkin, A Ya

2011-01-01T23:59:59.000Z

282

Dynamic Network Forecasting using SimGrid Simulations Matthieu Imbert and Eddy Caron  

E-Print Network (OSTI)

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

283

Simulant-material experimental investigation of flow dynamics in the CRBR Upper-Core Structure  

Science Conference Proceedings (OSTI)

The results of a simulant-material experimental investigation of flow dynamics in the Clinch River Breeder Reactor (CRBR) Upper Core Structure are described. The methodology used to design the experimental apparatus and select test conditions is detailed. Numerous comparisons between experimental data and SIMMER-II Code calculations are presented with both advantages and limitations of the SIMMER modeling features identified.

Wilhelm, D.; Starkovich, V.S.; Chapyak, E.J.

1982-09-01T23:59:59.000Z

284

A simulated annealing approach with probability matrix for semiconductor dynamic scheduling problem  

Science Conference Proceedings (OSTI)

The dynamic scheduling problem of semiconductor burn-in operations is studied in this paper. The burn-in oven is a batch-processing machine and the size of each job is independent of the oven's capacity. The processing time for each batch is represented ... Keywords: Deadlines, Heuristic, Simulated annealing, Total weighted completion time

Fuh-Der Chou; Hui-Mei Wang; Pei-Chann Chang

2008-11-01T23:59:59.000Z

285

DYNAMIC SIMULATION OF MONO-TUBE CAVITY RECEIVERS FOR DIRECT STEAM GENERATION  

E-Print Network (OSTI)

-tracing study of the heat flux distribution inside the steam receiver is used to spatially refine the modelDYNAMIC SIMULATION OF MONO-TUBE CAVITY RECEIVERS FOR DIRECT STEAM GENERATION José Zapata 1 , John dish has been in operation since 2010 with a mono-tube steam cavity receiver, the SG4 system

286

Dynamic Modeling and Simulation of Hybrid Power Systems Based on Renewable Energy  

Science Conference Proceedings (OSTI)

This paper describes dynamic modeling and simulation results of a renewable energy based hybrid power system. The paper focuses on the combination of solar cell (SC), wind turbine (WT), fuel cell (FC) and ultra-capacitor (UC) systems for power generation. ... Keywords: fuel cell, hybrid power system, renewable energy, solar cell, ultra-capacitor, wind turbine

Teng-Fa Tsao; Po-Hung Chen; Hung-Cheng Chen

2009-10-01T23:59:59.000Z

287

Research article: Fine grained sampling of residue characteristics using molecular dynamics simulation  

Science Conference Proceedings (OSTI)

In a fine-grained computational analysis of protein structure, we investigated the relationships between a residue's backbone conformations and its side-chain packing as well as conformations. To produce continuous distributions in high resolution, we ... Keywords: Backbone conformation, Dynameome, Molecular dynamics simulation, Ramachandran plot, Residue volume, Rotamer, Side-chain packing

Hyun Joo; Xiaotao Qu; Rosemarie Swanson; C. Michael McCallum; Jerry Tsai

2010-06-01T23:59:59.000Z

288

Gasificaton Transport: A Multiphase CFD Approach & Measurements  

DOE Green Energy (OSTI)

The objective of this project was to develop predictive theories for the dispersion and mass transfer coefficients and to measure them in the turbulent fluidization regime, using existing facilities. A second objective was to use our multiphase CFD tools to suggest optimized gasifier designs consistent with aims of Future Gen. We have shown that the kinetic theory based CFD codes correctly compute: (1) Dispersion coefficients; and (2) Mass transfer coefficients. Hence, the kinetic theory based CFD codes can be used for fluidized bed reactor design without any such inputs. We have also suggested a new energy efficient method of gasifying coal and producing electricity using a molten carbonate fuel cell. The principal product of this new scheme is carbon dioxide which can be converted into useful products such as marble, as is done very slowly in nature. We believe this scheme is a lot better than the canceled FutureGen, since the carbon dioxide is safely sequestered.

Dimitri Gidaspow; Veeraya Jiradilok; Mayank Kashyap; Benjapon Chalermsinsuwan

2009-02-14T23:59:59.000Z

289

Numerical Simulation of Liquid Metal Flows under the Influence of ...  

Science Conference Proceedings (OSTI)

A Coupled CFD-Thermodynamic-Kinetic Model to Simulate a Gas Stirred Ladle ... Exercise on Thermal and Thermosolutal Natural Convection in Liquid Alloys.

290

Particle dynamics in two-dimensional random energy landscapes - experiments and simulations  

E-Print Network (OSTI)

The dynamics of individual colloidal particles in random potential energy landscapes were investigated experimentally and by Monte Carlo simulations. The value of the potential at each point in the two-dimensional energy landscape follows a Gaussian distribution. The width of the distribution, and hence the degree of roughness of the energy landscape, was varied and its effect on the particle dynamics studied. This situation represents an example of Brownian dynamics in the presence of disorder. In the experiments, the energy landscapes were generated optically using a holographic set-up with a spatial light modulator, and the particle trajectories were followed by video microscopy. The dynamics are characterized using, e.g., the time-dependent diffusion coefficient, the mean squared displacement, the van Hove function and the non-Gaussian parameter. In both, experiments and simulations, the dynamics are initially diffusive, show an extended sub-diffusive regime at intermediate times before diffusive motion is recovered at very long times. The dependence of the long-time diffusion coefficient on the width of the Gaussian distribution agrees with theoretical predictions. Compared to the dynamics in a one-dimensional potential energy landscape, the localization at intermediate times is weaker and the diffusive regime at long times reached earlier, which is due to the possibility to avoid local maxima in two-dimensional energy landscapes.

Florian Evers; Christoph Zunke; Richard D. L. Hanes; Joerg Bewerunge; Imad Ladadwa; Andreas Heuer; Stefan U. Egelhaaf

2013-02-13T23:59:59.000Z

291

Numerical Simulation of Thunderstorm Outflow Dynamics. Part I: Outflow Sensitivity Experiments and Turbulence Dynamics  

Science Conference Proceedings (OSTI)

In this first paper of a two-part series, a two-dimensional numerical model is developed and used to investigate the dynamics of thunderstorm outflows. By focusing only on the outflow and using essentially inviscid equations and high spatial ...

Kelvin K. Droegemeier; Robert B. Wilhelmson

1987-04-01T23:59:59.000Z

292

A molecular dynamics simulation of the melting points and glass transition temperatures of myo-and neo-inositol  

E-Print Network (OSTI)

A molecular dynamics simulation of the melting points and glass transition temperatures of myo molecular potentials for atomistic simulation studies COMPASS H. Sun, J. Phys. Chem. B 102, 7338 1998 force field and molecular dynamics techniques. Our results show that the calculated heats of sublimation

de Gispert, Adrià

293

Molecular dynamics simulation of erosion and surface evolution of tungsten due to bombardment with deuterium and carbon in  

E-Print Network (OSTI)

Molecular dynamics simulation of erosion and surface evolution of tungsten due to bombardment Available online 24 May 2013 Keywords: Molecular dynamic simulation Carbon irradiation on tungsten t The behavior of tungsten as plasma facing material in fusion environment is investigated using molecular

Harilal, S. S.

294

Computational Particle Dynamic Simulations on Multicore Processors (CPDMu) Final Report â?? Phase I  

SciTech Connect

Statement of Problem - Department of Energy has many legacy codes for simulation of computational particle dynamics and computational fluid dynamics applications that are designed to run on sequential processors and are not easily parallelized. Emerging high-performance computing architectures employ massively parallel multicore architectures (e.g., graphics processing units) to increase throughput. Parallelization of legacy simulation codes is a high priority, to achieve compatibility, efficiency, accuracy, and extensibility. General Statement of Solution - A legacy simulation application designed for implementation on mainly-sequential processors has been represented as a graph G. Mathematical transformations, applied to G, produce a graph representation {und G} for a high-performance architecture. Key computational and data movement kernels of the application were analyzed/optimized for parallel execution using the mapping G {yields} {und G}, which can be performed semi-automatically. This approach is widely applicable to many types of high-performance computing systems, such as graphics processing units or clusters comprised of nodes that contain one or more such units. Phase I Accomplishments - Phase I research decomposed/profiled computational particle dynamics simulation code for rocket fuel combustion into low and high computational cost regions (respectively, mainly sequential and mainly parallel kernels), with analysis of space and time complexity. Using the research team's expertise in algorithm-to-architecture mappings, the high-cost kernels were transformed, parallelized, and implemented on Nvidia Fermi GPUs. Measured speedups (GPU with respect to single-core CPU) were approximately 20-32X for realistic model parameters, without final optimization. Error analysis showed no loss of computational accuracy. Commercial Applications and Other Benefits - The proposed research will constitute a breakthrough in solution of problems related to efficient parallel computation of particle and fluid dynamics simulations. These problems occur throughout DOE, military and commercial sectors: the potential payoff is high. We plan to license or sell the solution to contractors for military and domestic applications such as disaster simulation (aerodynamic and hydrodynamic), Government agencies (hydrological and environmental simulations), and medical applications (e.g., in tomographic image reconstruction). Keywords - High-performance Computing, Graphic Processing Unit, Fluid/Particle Simulation. Summary for Members of Congress - Department of Energy has many simulation codes that must compute faster, to be effective. The Phase I research parallelized particle/fluid simulations for rocket combustion, for high-performance computing systems.

Mark S. Schmalz

2011-07-24T23:59:59.000Z

295

NREL: Computational Science - Wind Energy Simulations  

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

Wind Energy Simulations Wind Energy Simulations Scientists in the Computational Science Center at the National Renewable Energy Laboratory (NREL) are performing wind-farm computational fluid dynamics (CFD) and structural dynamics simulations that will provide a better understanding of the interactions of wind turbine wakes with one another, with the surrounding winds, and with the loads they impose on turbine blades and other components. Large-scale wind power generation deployment is a realistic and largely inevitable proposition as energy security, supply uncertainties, and global climate concerns drive the U.S. to develop diverse sources of domestic, clean, and renewable energy. The U.S. is currently on a path to produce 20% of its electricity from wind energy by 2030, which is a 10-fold increase

296

Development of a dynamic simulator for a natural gas combined cycle (NGCC) power plant with post-combustion carbon capture  

Science Conference Proceedings (OSTI)

The AVESTAR Center located at the U.S. Department of Energy’s National Energy Technology Laboratory and West Virginia University is a world-class research and training environment dedicated to using dynamic process simulation as a tool for advancing the safe, efficient and reliable operation of clean energy plants with CO{sub 2} capture. The AVESTAR Center was launched with a high-fidelity dynamic simulator for an Integrated Gasification Combined Cycle (IGCC) power plant with pre-combustion carbon capture. The IGCC dynamic simulator offers full-scope Operator Training Simulator (OTS) Human Machine Interface (HMI) graphics for realistic, real-time control room operation and is integrated with a 3D virtual Immersive Training Simulator (ITS), thus allowing joint control room and field operator training. The IGCC OTS/ITS solution combines a “gasification with CO{sub 2} capture” process simulator with a “combined cycle” power simulator into a single high-performance dynamic simulation framework. This presentation will describe progress on the development of a natural gas combined cycle (NGCC) dynamic simulator based on the syngas-fired combined cycle portion of AVESTAR’s IGCC dynamic simulator. The 574 MW gross NGCC power plant design consisting of two advanced F-class gas turbines, two heat recovery steam generators (HRSGs), and a steam turbine in a multi-shaft 2x2x1 configuration will be reviewed. Plans for integrating a post-combustion carbon capture system will also be discussed.

Liese, E.; Zitney, S.

2012-01-01T23:59:59.000Z

297

Modeling the Forest or Modeling the Trees A Comparison of System Dynamics and Agent-Based Simulation  

E-Print Network (OSTI)

System Dynamics and Agent-based Simulation are two approaches that use computer simulation for investigating non-linear social and socio-economic systems with a focus on the understanding and qualitative prediction of a system’s behavior. Although the two schools have a broad overlap in research topics they have been relatively unnoticed by each other so far. This paper contributes to the cross-study of System Dynamics and Agent-Based Simulation. It uncovers and contrasts the primary conceptual predispositions underlying the two approaches. Moreover, ideas about how the approaches could be integrated are presented. Key words: System Dynamics, Agent-based Simulation

Nadine Schieritz; Peter M. Milling

2003-01-01T23:59:59.000Z

298

A GAUSSIAN PROCESS BASED APPROACH FOR HANDLING UNCERTAINTY IN VEHICLE DYNAMICS SIMULATION  

E-Print Network (OSTI)

Advances in vehicle modeling and simulation in recent years have led to designs that are safer, easier to handle, and less sensitive to external factors. Yet, the potential of simulation is adversely impacted by its limited ability to predict vehicle dynamics in the presence of uncertainty. A commonly occurring source of uncertainty in vehicle dynamics is the road-tire friction interaction, typically represented through a spatially distributed stochastic friction coefficient. The importance of its variation becomes apparent on roads with ice patches, where if the stochastic attributes of the friction coefficient are correctly factored into real time dynamics simulation, robust control strategies could be designed to improve transportation safety. This work concentrates on correctly accounting in the nonlinear dynamics of a car model for the inherent uncertainty in friction coefficient distribution at the road/tire interface. The outcome of this effort is the ability to quantify the effect of input uncertainty on a vehicle’s trajectory and the associated escalation of risk in driving. By using a space dependent Gaussian ? Address all correspondence to this author.

Kyle Schmitt; Justin Madsen; Mihai Anitescu; Dan Negrut

2008-01-01T23:59:59.000Z

299

Automatic differentiation of advanced CFD codes for multidisciplinary design  

SciTech Connect

Automated multidisciplinary design of aircraft and other flight vehicles requires the optimization of complex performance objectives with respect to a number of design parameters and constraints. The effect of these independent design variables on the system performance criteria can be quantified in terms of sensitivity derivatives which must be calculated and propagated by the individual discipline simulation codes. Typical advanced CFD analysis codes do not provide such derivatives as part of a flow solution; these derivatives are very expensive to obtain by divided (finite) differences from perturbed solutions. It is shown here that sensitivity derivatives can be obtained accurately and efficiently using the ADIFOR source translator for automatic differentiation. In particular, it is demonstrated that the 3-D, thin-layer Navier-Stokes, multigrid flow solver called TLNS3D is amenable to automatic differentiation in the forward mode even with its implicit iterative solution algorithm and complex turbulence modeling. It is significant that using computational differentiation, consistent discrete nongeometric sensitivity derivatives have been obtained from an aerodynamic 3-D CFD code in a relatively short time, e.g. O(man-week) not O(man-year).

Bischof, C.; Corliss, G.; Griewank, A. (Argonne National Lab., IL (United States)); Green, L.; Haigler, K.; Newman, P. (National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center)

1992-01-01T23:59:59.000Z

300

Automatic differentiation of advanced CFD codes for multidisciplinary design  

SciTech Connect

Automated multidisciplinary design of aircraft and other flight vehicles requires the optimization of complex performance objectives with respect to a number of design parameters and constraints. The effect of these independent design variables on the system performance criteria can be quantified in terms of sensitivity derivatives which must be calculated and propagated by the individual discipline simulation codes. Typical advanced CFD analysis codes do not provide such derivatives as part of a flow solution; these derivatives are very expensive to obtain by divided (finite) differences from perturbed solutions. It is shown here that sensitivity derivatives can be obtained accurately and efficiently using the ADIFOR source translator for automatic differentiation. In particular, it is demonstrated that the 3-D, thin-layer Navier-Stokes, multigrid flow solver called TLNS3D is amenable to automatic differentiation in the forward mode even with its implicit iterative solution algorithm and complex turbulence modeling. It is significant that using computational differentiation, consistent discrete nongeometric sensitivity derivatives have been obtained from an aerodynamic 3-D CFD code in a relatively short time, e.g. O(man-week) not O(man-year).

Bischof, C.; Corliss, G.; Griewank, A. [Argonne National Lab., IL (United States); Green, L.; Haigler, K.; Newman, P. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

1992-12-31T23:59:59.000Z

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


301

Beam dynamics and wakefield simulations of the double grating accelerating structure  

Science Conference Proceedings (OSTI)

Laser-driven acceleration in dielectric structures can provide gradients on the order of GeV/m. The small transverse dimension and tiny feature sizes introduce challenges in design, fabrication, and simulation studies of these structures. In this paper we present the results of beam dynamic simulation and short range longitudinal wakefield simulation of the double grating structure. We show the linear trend of acceleration in a dielectric accelerator design and calculate the maximum achievable gradient equal to 0.47E{sub 0} where E0 is maximum electric field of the laser excitation. On the other hand, using wakefield simulations, we show that the loss factor of the structure with 400nm gap size will be 0.12GV/m for a 10fC, 100as electron bunch which is an order of magnitude less than expected gradient near damage threshold of the device.

Najafabadi, B. Montazeri; Byer, R. L.; Ng, C. K.; England, R. J.; Peralta, E. A.; Soong, K.; Noble, R.; Wu, Z. [Stanford University, Stanford, CA (United States); SLAC National Accelerator Laboratory, Menlo Park, CA (United States)

2012-12-21T23:59:59.000Z

302

CFD Research Overview Dr. Chris Roy  

E-Print Network (OSTI)

/gallon, resulting in a total consumption of 26 billion gallons of diesel fuel · With diesel at $2.33/gallon high-efficiency CFD predictions (Roy) and conducting wind tunnel experiments (Devenport) · Auburn were not optimized to minimize drag Tractor-Trailer with Base Flaps Wind-Averaged Drag Coefficient #12

Roy, Chris

303

Beam dynamics simulations and measurements at the Project X Test Facility  

Science Conference Proceedings (OSTI)

Project X, under study at Fermilab, is a multitask high-power superconducting RF proton beam facility, aiming to provide high intensity protons for rare processes experiments and nuclear physics at low energy, and simultaneously for the production of neutrinos, as well as muon beams in the long term. A beam test facility - former known as High Intensity Neutrino Source (HINS) - is under commissioning for testing critical components of the project, e.g. dynamics and diagnostics at low beam energies, broadband beam chopping, RF power generation and distribution. In this paper we describe the layout of the test facility and present beam dynamics simulations and measurements.

Gianfelice-Wendt, E.; Scarpine, V.E.; Webber, R.C.; /Fermilab

2011-03-01T23:59:59.000Z

304

Interactions between Ether Phospholipids and Cholesterol as Determined by Scattering and Molecular Dynamics Simulations  

SciTech Connect

Cholesterol and ether lipids are ubiquitous in mammalian cell membranes, and their interactions are crucial in ether lipid mediated cholesterol trafficking. We report on cholesterol s molecular interactions with ether lipids as determined using a combination of small-angle neutron and Xray scattering, and all-atom molecular dynamics (MD) simulations. A scattering density profile model for an ether lipid bilayer was developed using MD simulations, which was then used to simultaneously fit the different experimental scattering data. From analysis of the data the various bilayer structural parameters were obtained. Surface area constrained MD simulations were also performed to reproduce the experimental data. This iterative analysis approach resulted in good agreement between the experimental and simulated form factors. The molecular interactions taking place between cholesterol and ether lipids were then determined from the validated MD simulations. We found that in ether membranes cholesterol primarily hydrogen bonds with the lipid headgroup phosphate oxygen, while in their ester membrane counterparts cholesterol hydrogen bonds with the backbone ester carbonyls. This different mode of interaction between ether lipids and cholesterol induces cholesterol to reside closer to the bilayer surface, dehydrating the headgroup s phosphate moiety. Moreover, the three-dimensional lipid chain spatial density distribution around cholesterol indicates anisotropic chain packing, causing cholesterol to tilt. These insights lend a better understanding of ether lipid-mediated cholesterol trafficking and the roles that the different lipid species have in determining the structural and dynamical properties of membrane associated biomolecules.

Pan, Jianjun [ORNL; Cheng, Xiaolin [ORNL; Heberle, Frederick A [ORNL; Mostofian, Barmak [ORNL; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Drazba, Paul [ORNL; Katsaras, John [ORNL

2012-01-01T23:59:59.000Z

305

An Event-Driven Hybrid Molecular Dynamics and Direct Simulation Monte Carlo Algorithm  

Science Conference Proceedings (OSTI)

A novel algorithm is developed for the simulation of polymer chains suspended in a solvent. The polymers are represented as chains of hard spheres tethered by square wells and interact with the solvent particles with hard core potentials. The algorithm uses event-driven molecular dynamics (MD) for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in event-driven algorithms, rather, the momentum and energy exchange in the solvent is determined stochastically using the Direct Simulation Monte Carlo (DSMC) method. The coupling between the solvent and the solute is consistently represented at the particle level, however, unlike full MD simulations of both the solvent and the solute, the spatial structure of the solvent is ignored. The algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard wall subjected to uniform shear. The algorithm closely reproduces full MD simulations with two orders of magnitude greater efficiency. Results do not confirm the existence of periodic (cycling) motion of the polymer chain.

Donev, A; Garcia, A L; Alder, B J

2007-07-30T23:59:59.000Z

306

Multi-dimensional computation of compressible reacting flows through porous media to apply to Internal Combustion Engine simulation  

Science Conference Proceedings (OSTI)

In this work, a new multi-dimensional Finite Volume (FV) solver of partial differential equations (PDEs) for compressible and reacting flows through porous media has been developed. The solver makes use of a pseudo-staggered arrangement, in order to ... Keywords: CFD, Computational fluid dynamics, DPF, Diesel exhaust after-treatment simulation, Diesel particulate filters, ICE, Internal combustion engines, Numerical methods, Porous media solver

F. Piscaglia; A. Montorfano; A. Onorati

2010-10-01T23:59:59.000Z

307

Energy of one-dimensional diatomic elastic granular gas: Theory and molecular dynamics Simulation  

E-Print Network (OSTI)

One-dimensional ideal diatomic gas is simulated through possible types of motion of a molecule. Energy of each type of its motion is calculated from theory and numerical method. Calculation of kinetic energy of an atom in translational-vibrational motion is not analytically simple, but it can be solved by numerical method of molecular dynamic simulation. This paper justifies that kinetic energy of a diatomic molecule can be determined by two different approaches. The first is the sum of kinetic energy of each atom and second is the sum of kinetic energy of translational motion and vibrational motion.

Khotimah, Siti Nurul; Widayani,; Waris, Abdul

2011-01-01T23:59:59.000Z

308

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

SciTech Connect

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

Germann, T. C. (Timothy C.)

2001-06-01T23:59:59.000Z

309

A new battery-charging method suggested by molecular dynamics simulations  

E-Print Network (OSTI)

Based on large-scale molecular dynamics simulations, we propose a new charging method that should be capable of charging a Lithium-ion battery in a fraction of the time needed when using traditional methods. This charging method uses an additional applied oscillatory electric field. Our simulation results show that this charging method offers a great reduction in the average intercalation time for Li+ ions, which dominates the charging time. The oscillating field not only increases the diffusion rate of Li+ ions in the electrolyte but, more importantly, also enhances intercalation by lowering the corresponding overall energy barrier.

Hamad, Ibrahim Abou; Wipf, D; Rikvold, P A; 10.1039/b920970k

2010-01-01T23:59:59.000Z

310

Numerical simulation of high-speed penetration-perforation dynamics in layered armor shields  

E-Print Network (OSTI)

Penetration models and calculating algorithms are presented, describing the dynamics and fracture of composite armor shields penetrated by high-speed small arms. A shield considered consists of hard (metal or ceramic) facing and multilayered fabric backing. A simple formula is proved for the projectile residual velocity after perforation of a thin facing. A new plastic-flow jet model is proposed for calculating penetration dynamics in the case of a thick facing of ceramic or metal-ceramic FGM materials. By bringing together the developed models into a calculating algorithm, a computer tool is designed enabling simulations of penetration processes in the above-mentioned shields and analysis of optimization problems. Some results of computer simulation are presented. It is revealed in particular that strength proof of pliable backing can be better as compared with more rigid backing. Comparison of calculations and test data shows sufficient applicability of the models and the tool.

Ayzenberg-Stepanenko, Mark

2012-01-01T23:59:59.000Z

311

Numerical simulation of high-speed penetration-perforation dynamics in layered armor shields  

E-Print Network (OSTI)

Penetration models and calculating algorithms are presented, describing the dynamics and fracture of composite armor shields penetrated by high-speed small arms. A shield considered consists of hard (metal or ceramic) facing and multilayered fabric backing. A simple formula is proved for the projectile residual velocity after perforation of a thin facing. A new plastic-flow jet model is proposed for calculating penetration dynamics in the case of a thick facing of ceramic or metal-ceramic FGM materials. By bringing together the developed models into a calculating algorithm, a computer tool is designed enabling simulations of penetration processes in the above-mentioned shields and analysis of optimization problems. Some results of computer simulation are presented. It is revealed in particular that strength proof of pliable backing can be better as compared with more rigid backing. Comparison of calculations and test data shows sufficient applicability of the models and the tool.

Mark Ayzenberg-Stepanenko; Grigory Osharovich

2012-03-07T23:59:59.000Z

312

Advanced Process Engineering Co-simulation  

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

7 7 AdvAnced Process engineering co-simulAtion Description The National Energy Technology Laboratory (NETL) and its R&D collaboration partners are developing the Advanced Process Engineering Co-Simulator (APECS) as an innovative software tool that combines process simulation with high-fidelity equipment models based on computational fluid dynamics (CFD). Winner of a 2004 R&D 100 Award and a 2007 Federal Laboratory Consortium (FLC) Excellence in Technology Transfer Award, this powerful co-simulation technology, for the first time, provides the necessary level of detail and accuracy essential for engineers to analyze and optimize the coupled fluid flow, heat and mass transfer, and chemical reactions that drive overall plant performance. Combined with advanced visualization and high-performance computing,

313

Bayesian uncertainty quantification and propagation in molecular dynamics simulations: A high performance computing framework  

Science Conference Proceedings (OSTI)

We present a Bayesian probabilistic framework for quantifying and propagating the uncertainties in the parameters of force fields employed in molecular dynamics (MD) simulations. We propose a highly parallel implementation of the transitional Markov chain Monte Carlo for populating the posterior probability distribution of the MD force-field parameters. Efficient scheduling algorithms are proposed to handle the MD model runs and to distribute the computations in clusters with heterogeneous architectures. Furthermore

Panagiotis Angelikopoulos; Costas Papadimitriou; Petros Koumoutsakos

2012-01-01T23:59:59.000Z

314

A Gaussian process-based approach for handling uncertainty in vehicle dynamics simulation.  

Science Conference Proceedings (OSTI)

Advances in vehicle modeling and simulation in recent years have led to designs that are safer, easier to handle, and less sensitive to external factors. Yet, the potential of simulation is adversely impacted by its limited ability to predict vehicle dynamics in the presence of uncertainty. A commonly occurring source of uncertainty in vehicle dynamics is the road-tire friction interaction, typically represented through a spatially distributed stochastic friction coefficient. The importance of its variation becomes apparent on roads with ice patches, where if the stochastic attributes of the friction coefficient are correctly factored into real time dynamics simulation, robust control strategies could be designed to improve transportation safety. This work concentrates on correctly accounting in the nonlinear dynamics of a car model for the inherent uncertainty in friction coefficient distribution at the road/tire interface. The outcome of this effort is the ability to quantify the effect of input uncertainty on a vehicle's trajectory and the associated escalation of risk in driving. By using a space-dependent Gaussian process, the statistical representation of the friction coefficient allows for consistent space dependence of randomness. The approach proposed allows for the incorporation of noise in the observed data and a nonzero mean for inhomogeneous distribution of the friction coefficient. Based on the statistical model considered, consistent friction coefficient sample distributions are generated over large spatial domains of interest. These samples are subsequently used to compute and characterize the statistics associated with the dynamics of a nonlinear vehicle model. The information concerning the state of the road and thus the friction coefficient is assumed available (measured) at a limited number of points by some sensing device that has a relatively homogeneous noise field (satellite picture or ground sensors, for instance). The methodology proposed can be modified to incorporate information that is sensed by each individual car as it advances along its trajectory.

Schmitt, K.; Madsen, J.; Anitescu, M.; Negrut, D.; Mathematics and Computer Science; Univ. of Wisconsin at Madison

2009-01-01T23:59:59.000Z

315

Advanced beam-dynamics simulation tools for the RIA driver linac,Part I: Low energy beam transport and radiofrequency quadrupole  

Science Conference Proceedings (OSTI)

Advanced Beam-Dynamics Simulation Tools for the RIA Driver Linac; Low Energy Beam Transport and Radiofrequency Quadrupole.

Wangler, Thomas P.; Crandall, Kenneth R.; Garnett, Robert W.; Gorelov, Dmitry; Ostroumov, Petr; Qiang, Ji; Ryne, Robert; York, Richard

2003-08-26T23:59:59.000Z

316

A dynamic object-oriented architecture approach to ecosystem modeling and simulation.  

SciTech Connect

Modeling and simulation in support of adaptive ecosystem management can be better accomplished through a dynamic, integrated, and flexible approach that incorporates scientific and technological components into a comprehensive ecosystem-modeling framework. The Integrated Dynamic Landscape Analysis and Modeling System (IDLAMS) integrates ecological models and decision support techniques, through a geographic information system (GIS)-based framework. The Strategic Environmental Research and Development Program (SERDP) sponsored the development of IDLAMS. Initially built upon a GIS framework, IDLAMS is migrating to an object-oriented (OO) architectural framework. An object-oriented architecture is more flexible and modular. It allows disparate applications and dynamic models to be integrated in a manner that minimizes (or eliminates) the need to rework or recreate the system as new models are added to the suite. In addition, an object-oriented design makes it easier to provide run-time feedback among models, thereby making it a more dynamic tool for exploring and providing insight into the interactions among ecosystem processes. Finally, an object-oriented design encourages the reuse of existing technology because OO-IDLAMS is able to integrate disparate models, databases, or applications executed in their native languages. Reuse is also accomplished through a structured approach to building a consistent and reusable object library. This reusability can substantially reduce the time and effort needed to develop future integrated ecosystem simulations.

Dolph, J. E.; Majerus, K. A.; Sydelko, P. J.; Taxon, T. N.

1999-04-09T23:59:59.000Z

317

Finite Element Modelling and Molecular Dynamic Simulations of Carbon nanotubes/ Polymer Composites  

E-Print Network (OSTI)

Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading have been analyzed. Elastic moduli and thermal coefficient of expansion are calculated and their variation with diameter and length is investigated. In particular, the nanotubes are modeled using 3D elastic beam finite elements with six degrees of freedom at each node. The difficulty in modeling multi walled nanotubes is the van der Waal's forces between adjacent layers which are geometrically non linear in nature. These forces are modeled using truss elements. The nanotube-polymer interface in a nano-composite is modeled on a similar basis. While performing the molecular dynamic simulations, the geometric optimization is performed initially to obtain the minimized configuration and then the desired temperature is attained by rescaling the velocities of carbon atoms in the nanotube. Results show that the Young's modulus increases with tube diameter in molecular mechanics whereas decreases in molecular dynamics since the inter-atomic potential due to chemical reactions between the atoms is taken into consideration in molecular dynamics unlike in molecular mechanics.

Gaddamanugu, Dhatri

2009-05-01T23:59:59.000Z

318

Abstract A COUPLED CFD FINITE ELEMENT ANALYSIS METHODOLOGY IN A BIFURCATION PIPE IN A NUCLEAR PLANT HEAT EXCHANGER  

E-Print Network (OSTI)

The accurate calculation of temperature distribution in key parts of a nuclear plant plays a crucial role in maximising the power output and the plant efficiency, whilst ensuring safe operation. The need for making the most profitable use of the available sources of energy requires the full exploitation of plant operational capacity. Temperature dependent material properties mean that increasing the power output in a nuclear plant may reduce the life of the welds in the pipes of the heat exchanger (boiler), operating in very demanding conditions. Rolls-Royce plc was requested to come up with a suitable solution that shielded critical pipe weld locations, reducing local temperatures, so allowing a useful increase in power output from the plant. Part of the heat shield design process was a comprehensive thermal analysis of the installation. Traditionally fluid and solid simulations are conducted separately or using conjugate analysis. Standard methods rely on the application of boundary conditions to the wall surface, which are commonly based on empirical heat transfer coefficient correlations or approximate read across of the CFD results. An alternative approach using conjugate calculations can be adopted, but the computational cost and meshing difficulties in matching the fluid and solid grids makes this unaffordable in terms of analysis time. This paper presents the application of an improved method using a communication library (SC89) between the in-house finite element (FE) code SC03, and the commercial computational fluid dynamics (CFD) code FLUENT. The method has been validated using test data from a Perspex model, where heat transfer coefficients were measured using a transient liquid crystal technique.

J. A. Dixon; A. Guijarro Valencia; P. Irel; P. Ridl; N. Hills

2010-01-01T23:59:59.000Z

319

High Performance Flow Simulations on Graphics Processing Units  

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

High Performance Flow Simulations on Graphics Processing Units High Performance Flow Simulations on Graphics Processing Units Speaker(s): Wangda Zuo Date: June 17, 2010 - 12:00pm Location: 90-3122 Seminar Host/Point of Contact: Michael Wetter Building design and operation often requires real-time or faster-than-real-time simulations for detailed information on air distributions. However, none of the current flow simulation techniques can satisfy this requirement. To solve this problem, a Fast Fluid Dynamics (FFD) model has been developed. The FFD can solve Navier-Stokes equations at a speed of 50 times faster than Computational Fluid Dynamics (CFD). In addition, the computing speed of the FFD program has been further enhanced up to 30 times by executing in parallel on a Graphics Processing Unit (GPU) instead of a Central Processing Unit (CPU). As a whole, the FFD on a GPU

320

Research on Ammonium Bisulfate Formation in Air Preheaters - Experimental Investigation and CFD Modeling  

Science Conference Proceedings (OSTI)

Ammonium bisulfate (ABS) formation and deposition is the most common operating problem affecting air preheaters (APHs) in fossil power plants with post combustion NOx controls that use selective noncatalytic reduction (SNCR) or selective catalytic reduction (SCR). This report describes pilot-scale experiments conducted to better understand ABS chemistry and efforts to develop a computational fluid dynamics (CFD) model of an APH to identify the key phenomena that may affect ABS formation and deposition.

2008-06-30T23:59:59.000Z

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


321

A molecular dynamics simulation of DNA damage induction by ionizing radiation  

E-Print Network (OSTI)

We present a multi-scale simulation of early stage of DNA damages by the indirect action of hydroxyl ($^\\bullet$OH) free radicals generated by electrons and protons. The computational method comprises of interfacing the Geant4-DNA Monte Carlo with the ReaxFF molecular dynamics software. A clustering method was employed to map the coordinates of $^\\bullet$OH-radicals extracted from the ionization track-structures onto nano-meter simulation voxels filled with DNA and water molecules. The molecular dynamics simulation provides the time evolution and chemical reactions in individual simulation voxels as well as the energy-landscape accounted for the DNA-$^\\bullet$OH chemical reaction that is essential for the first principle enumeration of hydrogen abstractions, chemical bond breaks, and DNA-lesions induced by collection of ions in clusters less than the critical dimension which is approximately 2-3 \\AA. We show that the formation of broken bonds leads to DNA base and backbone damages that collectively propagate ...

Abolfath, Ramin M; Chen, Zhe J; Nath, Ravinder

2013-01-01T23:59:59.000Z

322

Dissipative Particle Dynamics Simulation of Pore-Scale Multiphase Fluid Flow  

Science Conference Proceedings (OSTI)

Multiphase fluid flow through porous media involves complex fluid dynamics, and it is difficult to model such complex behavior, on the pore scale, using grid-based continuum models. In this paper, the application of dissipative particle dynamics (DPD), a relatively new mesoscale method, to the simulation of pore-scale multiphase fluid flows under a variety of flow conditions is described. We demonstrate that the conventional DPD method using purely repulsive conservative (nondissipative) particle-particle interactions is capable of modeling single-phase flow fields in saturated porous media. In order to simulate unsaturated multiphase flow through porous media, we applied a modified model for the conservative particle-particle interactions that combines short-range repulsive and long-range attractive interactions. This form for the conservative particle-particle interactions allows the behavior of multiphase systems consisting of gases, liquids, and solids to be simulated. We also demonstrated that the flow of both wetting and nonwetting fluids through porous media can be simulated by controlling the ratios between the fluid-fluid and fluid-solid (fluid-wall) interparticle interaction strengths.

Paul Meakin; Hai Huang; Moubin Liu

2007-04-01T23:59:59.000Z

323

A multi-scale approach to molecular dynamics simulations of shock waves  

DOE Green Energy (OSTI)

Study of the propagation of shock waves in condensed matter has led to new discoveries ranging from new metastable states of carbon [1] to the metallic conductivity of hydrogen in Jupiter, [2] but progress in understanding the microscopic details of shocked materials has been extremely difficult. Complications can include the unexpected formation of metastable states of matter that determine the structure, instabilities, and time-evolution of the shock wave. [1,3] The formation of these metastable states can depend on the time-dependent thermodynamic pathway that the material follows behind the shock front. Furthermore, the states of matter observed in the shock wave can depend on the timescale on which observation is made. [4,1] Significant progress in understanding these microscopic details has been made through molecular dynamics simulations using the popular non-equilibrium molecular dynamics (NEMD) approach to atomistic simulation of shock compression. [5] The NEMD method involves creating a shock at one edge of a large system by assigning some atoms at the edge a fixed velocity. The shock propagates across the computational cell to the opposite side. The computational work required by NEMD scales at least quadratically in the evolution time because larger systems are needed for longer simulations to prevent the shock wave from reflecting from the edge of the computational cell and propagating back into the cell. When quantum mechanical methods with poor scaling of computational effort with system size are employed, this approach to shock simulations rapidly becomes impossible.

Reed, E J; Fried, L E; Manaa, M R; Joannopoulos, J D

2004-09-03T23:59:59.000Z

324

A 2-D Test Problem for CFD Modeling Heat Transfer in Spent Fuel Transfer Cask Neutron Shields  

SciTech Connect

In the United States, commercial spent nuclear fuel is typically moved from spent fuel pools to outdoor dry storage pads within a transfer cask system that provides radiation shielding to protect personnel and the surrounding environment. The transfer casks are cylindrical steel enclosures with integral gamma and neutron radiation shields. Since the transfer cask system must be passively cooled, decay heat removal from spent nuclear fuel canister is limited by the rate of heat transfer through the cask components, and natural convection from the transfer cask surface. The primary mode of heat transfer within the transfer cask system is conduction, but some cask designs incorporate a liquid neutron shield tank surrounding the transfer cask structural shell. In these systems, accurate prediction of natural convection within the neutron shield tank is an important part of assessing the overall thermal performance of the transfer cask system. The large-scale geometry of the neutron shield tank, which is typically an annulus approximately 2 meters in diameter but only 5-10 cm in thickness, and the relatively small scale velocities (typically less than 5 cm/s) represent a wide range of spatial and temporal scales that contribute to making this a challenging problem for computational fluid dynamics (CFD) modeling. Relevant experimental data at these scales are not available in the literature, but some recent modeling studies offer insights into numerical issues and solutions; however, the geometries in these studies, and for the experimental data in the literature at smaller scales, all have large annular gaps that are not prototypic of the transfer cask neutron shield. This paper presents results for a simple 2-D problem that is an effective numerical analog for the neutron shield application. Because it is 2-D, solutions can be obtained relatively quickly allowing a comparison and assessment of sensitivity to model parameter changes. Turbulence models are considered as well as the tradeoff between steady state and transient solutions. Solutions are compared for two commercial CFD codes, FLUENT and STAR-CCM+. The results can be used to provide input to the CFD Best Practices for this application. Following study results for the 2-D test problem, a comparison of simulation results is provided for a high Rayleigh number experiment with large annular gap. Because the geometry of this validation is significantly different from the neutron shield, and due to the critical nature of this application, the argument is made for new experiments at representative scales

Zigh, Ghani; Solis, Jorge; Fort, James A.

2011-01-14T23:59:59.000Z

325

Molecular dynamics simulations of swift heavy ion induced defect recovery in SiC  

SciTech Connect

Swift heavy ions induce a high density of electronic excitations that can cause the formation of amorphous ion tracks in insulators. No ion tracks have been observed in the semiconductor SiC, but recent experimental work suggests that irradiation damaged SiC can undergo defect recovery under swift heavy ion irradiation. It is believed that local heating of the lattice due to the electronic energy deposition can anneal, and thereby recover, some of the disordered structure. We simulate the local heating due to the ions by the inelastic thermal spike model and perform molecular dynamics simulations of dierent model damage states to study the defect recovery on an atomistic level. We find significant recovery of point defects and a disordered layer, as well as recrystallization at the amorphous-to-crystalline interface of an amorphous layer. The simulation results support the swift heavy ion annealing hypothesis.Swift heavy ions induce a high density of electronic excitations that can cause the formation of amorphous ion tracks in insulators. No ion tracks have been observed in the semiconductor SiC, but recent experimental work suggests that irradiation damaged SiC can undergo defect recovery under swift heavy ion irradiation. It is believed that local heating of the lattice due to the electronic energy deposition can anneal, and thereby recover, some of the disordered structure. We simulate the local heating due to the ions by the inelastic thermal spike model and perform molecular dynamics simulations of dierent model damage states to study the defect recovery on an atomistic level. We find significant recovery of point defects and a disordered layer, as well as recrystallization at the amorphous-to-crystalline interface of an amorphous layer. The simulation results support the swift heavy ion annealing hypothesis.

Backman, Marie [University of Tennessee, Knoxville (UTK); Toulemonde, Marcel [CEA-CNRS-ENSICAEN-University of Caen, FRANCE; Pakarinen, Olli H [University of Helsinki; Juslin, Niklas [University of Tennessee, Knoxville (UTK); Djurabekova, Flyura [University of Helsinki; Nordlund, Kai [University of Helsinki; Debelle, Aurelien [Universite Paris Sud, Orsay, France; Weber, William J [ORNL

2013-01-01T23:59:59.000Z

326

Simulation of the atmospheric behavior for the environment of a small-scale wind turbine.  

E-Print Network (OSTI)

??This study investigates a method using computational fluid dynamics (CFD) to model low-elevation atmospheric conditions. There are three goals in this research: to analyze the… (more)

Nguyen, Viet

2011-01-01T23:59:59.000Z

327

Numerical Simulation of an Open Channel Ultraviolet Waste-water Disinfection Reactor.  

E-Print Network (OSTI)

??The disinfection characteristics of an open channel ultra-violet (UV) wastewater disinfection reactor are investigated using a computational fluid dynamics (CFD) model. The model is based… (more)

Saha, Rajib Kumar

2013-01-01T23:59:59.000Z

328

Mesh Requirement Investigation for 2D and 3D Aerodynamic Simulation of Vertical Axis Wind Turbines.  

E-Print Network (OSTI)

??The accuracy of a Computational Fluid Dynamics (CFD) model to capture the complex flow around a small vertical axis wind turbine (VAWT) on 2D and… (more)

Naghib Zadeh, Saman

2013-01-01T23:59:59.000Z

329

Integrated dynamic and simulation model on coupled closed-loop workstation capacity controls in a multi-workstation production system  

Science Conference Proceedings (OSTI)

In this paper, a dynamic model coupled with a simulation model is introduced to control a multi-workstation production system such that a given performance measure is achieved. In particular, we consider closed loop capacity controls for regulating WIP ...

Tao Wu; Leyuan Shi; Benjamin Quirt; N. A. Duffie

2008-12-01T23:59:59.000Z

330

Unsteady Flow Visualization at Part-Load Conditions of a Radial Diffuser Pump: by PIV and CFD  

Science Conference Proceedings (OSTI)

The present study provides flow visualization on complex internal flows in a radial diffuser pump under part-load conditions by using the three-dimensional Navier-Stokes code CFX-10 with Detached Eddy Simulation (DES) turbulence model. Particle Image ... Keywords: CFD, Flow separation, Flow visualization, PIV, Radial pump

J. Feng; F.-K. Benra; H. J. Dohmen

2009-01-01T23:59:59.000Z

331

REVIEW OF EXPERIMENTAL CAPABILITIES AND HYDRODYNAMIC DATA FOR VALIDATION OF CFD BASED PREDICTIONS FOR SLURRY BUBBLE COLUMN REACTORS  

DOE Green Energy (OSTI)

The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.

Donna Post Guillen; Daniel S. Wendt

2007-11-01T23:59:59.000Z

332

REVIEW OF EXPERIMENTAL CAPABILITIES AND HYDRODYNAMIC DATA FOR VALIDATION OF CFD-BASED PREDICTIONS FOR SLURRY BUBBLE COLUMN REACTORS  

DOE Green Energy (OSTI)

The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.

Donna Post Guillen; Daniel S. Wendt; Steven P. Antal; Michael Z. Podowski

2007-11-01T23:59:59.000Z

333

Simulating dislocation loop internal dynamics and collective diffusion using stochastic differential equations  

Science Conference Proceedings (OSTI)

Nanoscale prismatic loops are modeled via a partial stochastic differential equation that describes an overdamped continuum elastic string, with a view to describing both the internal and collective dynamics of the loop as a function of temperature. Within the framework of the Langevin equation, expressions are derived that relate the empirical parameters of the model, the friction per unit length, and the elastic stiffness per unit length, to observables that can be obtained directly via molecular-dynamics simulations of interstitial or vacancy prismatic loop mobility. The resulting expressions naturally exhibit the properties that the collective diffusion coefficient of the loop (i) scales inversely with the square root of the number of interstitials, a feature that has been observed in both atomistic simulation and in situ TEM investigations of loop mobility, and (ii) the collective diffusion coefficient is not at all dependent on the internal interactions within the loop, thus qualitatively rationalizing past simulation results showing that the characteristic migration energy barrier is comparable to that of a single interstitial, and cluster migration is a result of individual (but correlated) interstitial activity.

Derlet, P. M.; Gilbert, M. R.; Dudarev, S. L. [Condensed Matter Theory Group, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); EURATOM/CCFE Fusion Association, Culham Centre for Fusion Energy, Oxfordshire OX14 3DB (United Kingdom)

2011-10-01T23:59:59.000Z

334

CFD Domain and Turbulence Model  

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

Improving Durability of Turbine Components Improving Durability of Turbine Components Through Trenched Film Cooling and Contoured Endwalls Principal Investigator: Prof. David G. Bogard University of Texas at Austin Graduate research assistant: Todd Davidson Co-Principal Investigator: Prof. Karen A. Thole Pennsylvania State University Graduate research assistant: TBD Background image: [Hamed, A., Tabakoff, W., and Wenglarz, R., 2006] UTSR Peer Review Workshop October 20, 2010 2 Project Objectives a. Evaluate the degradation of performance for trench and crater film cooling configurations when subjected to active deposition of contaminants. This will be done on simulated vane and endwall models. b. Design improved trench or crater film cooling configurations that mitigate the degradation effects of deposition of contaminants.

335

Computational Fluid Dynamics Modeling of Atmospheric Flow Applied to Wind Energy Research.  

E-Print Network (OSTI)

??High resolution atmospheric flow modeling using computational fluid dynamics (CFD) has many applications in the wind energy industry. A well designed model can accurately calculate… (more)

Russell, Alan

2009-01-01T23:59:59.000Z

336

CFD Calculation of Nitrogen Gas Quenching for Steel Ring Gears  

Science Conference Proceedings (OSTI)

In this study, we present CFD calculations of gas quenching process during the ... Exercise on Thermal and Thermosolutal Natural Convection in Liquid Alloys.

337

The Limitations of CFD Modeling for Furnace Atmosphere ... - TMS  

Science Conference Proceedings (OSTI)

Feb 1, 2002 ... The Limitations of CFD Modeling for Furnace Atmosphere Troubleshooting by P.F. Stratton, N. Saxena and M. Huggahalli ...

338

CFD Modelling of Heat Transfer in Supersonic Nozzles for ... - TMS  

Science Conference Proceedings (OSTI)

May 1, 2007 ... CFD Modelling of Heat Transfer in Supersonic Nozzles for Magnesium Production by Peter Witt, M.N.H. Khan, and Geoffrey Brooks ...

339

CFD Modeling and Analysis of Casting of Energetic Materials in ...  

Science Conference Proceedings (OSTI)

Multiphase Flow in a Steelmaking Converter Using an Unconventional Lance · Multiphysics CFD Modeling of a Free Falling Jet during Melt-Blowing Slag ...

340

Development of dynamic models of reactive distillation columns for simulation and determination of control  

E-Print Network (OSTI)

Dynamic models of a reactive distillation column have been developed and implemented in this work. A model describing the steady state behavior of the system has been built in a first step. The results from this steady state model have been compared to data provided from an industrial collaborator and the reconciled model formed the basis for the development of a dynamic model. Four controlled and four manipulated variables have been determined in a subsequent step and step tests for the manipulated variables were simulated. The data generated by the step responses was used for fitting transfer functions between the manipulated and the controlled variables. RGA analysis was performed to find the optimal pairing for controller design. Feedback controllers of PID type were designed between the paired variables found from RGA and the controllers were implemented on the column model. Both servo and regulatory problems have been considered and tested.

Chakrabarty, Arnab

2004-12-01T23:59:59.000Z

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


341

Simulation model and the dynamics of relative poverty rates in the presence of some social benefits in Romania  

Science Conference Proceedings (OSTI)

This paper presents some simulations of the relative poverty rates values in the presence of some social benefits in the income of persons / households considered in the Household Budget Survey carried out by the National Institute of Statistics of Romania ... Keywords: dynamics, indicators, relative poverty, simulation model, social benefits

Cristina Stroe; Andreea Cambir; Cornelia Barti; Eva Militaru; Silvia Cojanu; Eliza Lungu; Codruta Dragoiu; Isadora Lazar

2011-07-01T23:59:59.000Z

342

Abstract--A stochastic dynamic programming hydrothermal dispatch model to simulate a bid-based market is  

E-Print Network (OSTI)

on dynamic programming that optimizes and validates the bid prices strategies for each power plant in a hydro-thermal, and simulating them as if they were a single power plant. In a hydro-thermal system as the one simulated several plants. Emphasis is given to hydro reservoir modeling and to the assessment of their market power

Catholic University of Chile (Universidad Católica de Chile)

343

A Simulation Environment for the Dynamic Evaluation of Disaster Preparedness Policies  

E-Print Network (OSTI)

, PhD; Chris Barrett, PhD r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r D and interventions in the days following disasters. Author Affiliation: Network Dynamics and Simulation Science

Swarup, Samarth

344

Visualization of parallel molecular dynamics simulation on a remote visualization platform  

SciTech Connect

Visualization requires high performance computers. In order to use these shared high performance computers located at national centers, the authors need an environment for remote visualization. Remote visualization is a special process that uses computing resources and data that are physically distributed over long distances. In their experimental environment, a parallel raytracer is designed for the rendering task. It allows one to efficiently visualize molecular dynamics simulations represented by three dimensional ball-and-stick models. Different issues encountered in creating their platform are discussed, such as I/O, load balancing, and data distribution.

Lee, T.Y.; Raghavendra, C.S. [Washington State Univ., Pullman, WA (United States); Nicholas, J.B. [Pacific Northwest Lab., Richland, WA (United States). Molecular Science Research Center

1994-09-01T23:59:59.000Z

345

A simulation model of Rio Grande wild turkey dynamics in the Edwards Plateau of Texas  

E-Print Network (OSTI)

I investigated the effect of precipitation and predator abundance on Rio Grande wild turkey (Meleagris gallopavo; RGWT) in Texas. My results suggested that RGWT production was strongly correlated with cumulative winter precipitation over the range of the RGWT in Texas. However, I found no evidence that predator abundance influenced RGWT production, although spatial-asynchrony of predator populations at multiple spatial scales might have masked broad-scale effects. Using the results of these analyses, as well as empirical data derived from the literature and from field studies in the southern Edwards Plateau, I developed a stochastic, density-dependent, sex- and agespecific simulation model of wild turkey population dynamics. I used the model to evaluate the effect of alternative harvest management strategies on turkey populations. Sensitivity analysis of the model suggested that shape of the density-dependence relationship, clutch size, hatchability, juvenile sex ratio, poult survival, juvenile survival, and nonbreeding hen mortality most strongly influenced model outcome. Of these, density-dependence, sex ratio, and juvenile survival were least understood and merit further research. My evaluation of fall hen harvest suggested that current rates do not pose a threat to turkey populations. Moreover, it appears that hen harvest can be extended to other portions of the RGWT range without reducing turkey abundance, assuming that population dynamics and harvest rates are similar to those in the current fall harvest zone. Finally, simulation of alternative hen harvest rates suggested that rates ?5% of the fall hen population resulted in significant declines in the simulated population after 25 years, and rates ?15% resulted in significant risk of extinction to the simulated population.

Schwertner, Thomas Wayne

2003-05-01T23:59:59.000Z

346

Practical issues on CFD use and some industry aspects on research with CFD  

E-Print Network (OSTI)

of non-catalytic NOx reduction in FBC freeboard CFD project planning Fast pyrolysis model, 18.6.2010 2-catalytic NOx reduction in FBC freeboard target: Finding optimal locations for urea injection Injections temperature for NOx reduction is between blue and red areas. Courtesy Metso Power Oy #12;Geometry Fast

Zevenhoven, Ron

347

Cell dynamics simulation of droplet and bridge formation within striped nano-capillaries  

E-Print Network (OSTI)

The kinetics of droplet and bridge formation within striped nano-capillaries is studied when the wetting film grows via interface-limited growth. The phenomenological time-dependent Ginzburg-Landau (TDGL)-type model with thermal noise is used and numerically solved using the cell dynamics method. The model is two-dimensional and consists of undersaturated vapor confined within a nano-capillary made of two infinitely wide flat substrates. The surface of the substrate is chemically heterogeneous with a single stripe of lyophilic domain that exerts long-range attractive potential to the vapor molecule. The dynamics of nucleation and subsequent growth of droplet and bridge can be simulated and visualized. In particular, the evolution of the morphology from droplet or bump to bridge is clearly identified. Crucial role played by the substrate potential on the morphology of bridge of nanoscopic size is clarified. Nearly temperature-independent evolution of capillary condensation is predicted when the interface-limited growth dominates. In addition, it is shown that the dynamics of capillary condensation follows the scenario of capillary condensation proposed by Everett and Haynes three decades ago.

Masao Iwamatsu

2007-08-13T23:59:59.000Z

348

Simulating Collisions for Hydrokinetic Turbines  

SciTech Connect

Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.

Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.

2013-10-01T23:59:59.000Z

349

Dynamics  

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

Hydration Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation E. Mamontov,* ,† D. J. Wesolowski, ‡ L. Vlcek, § P. T. Cummings, §,| J. Rosenqvist, ‡ W. Wang, ⊥ and D. R. Cole ‡ Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473, Chemical Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, Department of Chemical Engineering, Vanderbilt UniVersity, NashVille, Tennessee 37235-1604, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6496, and EnVironmental Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6036 ReceiVed: December 20, 2007; ReVised Manuscript ReceiVed: June 4, 2008 The high energy resolution, coupled with the wide dynamic range, of the new backscattering

350

Equation of state of dense plasmas by ab initio simulations: Bridging the gap between quantum molecular dynamics and orbital-free molecular dynamics at high temperature  

SciTech Connect

The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on the Thomas-Fermi semiclassical approximation and possibly on a gradient correction, is the only simulation method currently available at high temperature. We show in the case of a dense boron plasma that the two approaches give pressures differing by a few percent even at temperatures as high as a few tens of electron-volts. We indicate how the pressures obtained by orbital-free molecular dynamics can be corrected in order to appear as a limit of the quantum molecular dynamics results as temperature increases. We thus obtain a method to calculate the equation of state of a dense plasma up to high temperatures where quantum molecular dynamics cannot be directly implemented.

Danel, J.-F.; Kazandjian, L.; Zerah, G. [CEA, DAM, DIF, F-91297 Arpajon (France)

2012-12-15T23:59:59.000Z

351

A Finite Element-Multibody Dynamics Co-simulation Methodology Applied to FAST  

E-Print Network (OSTI)

A co-simulation methodology is explored whereby a finite element code and a multi-body dynamics code featuring flexible cantilevered beams can be coupled and interactively executed. The floating frame of reference formulation is used to develop the equations of motion. The floating frame is fixed at the blade root. Such a formulation results in ordinary differential equations without added algebraic constraints. A variety of loose coupling and tight coupling schemes are examined for this problem. To synchronize the coupling variables, a Gauss-Seidel type iterative algorithm is used. The resulting fixed-point iterations are accelerated using Aitken’s adaptive relaxation technique. The methodology is evaluated for FAST, a wind turbine aeroelastic simulation code developed by NREL. As with FAST, many multi-body codes which can model flexibility employ modal methods. A proposed addition for FAST to simulate flexible effects using a finite element method module offers a potential to include a variety of non-linearities and also provides possibilities for using a high-fidelity aerodynamics module. The coupling schemes are compared and their applicability and limitations for different scenarios are pointed out. Results validating the approach are provided.

Suryakumar, Vishvas Samuel

2013-05-01T23:59:59.000Z

352

How trehalose protects DNA in the dry state: a molecular dynamics simulation  

E-Print Network (OSTI)

Molecular dynamics simulations were conducted on a system consisting of a decamer DNA solvated by trehalose and water (molecular ratio= 1:2), to mimic a relatively dry state for the DNA molecule. Simulations were performed at two different temperatures, 300 K and 450 K. The B-form DNA structure was shown to be stable at both temperatures. The analysis of hydrogen bonds between trehalose/water and DNA revealed that trehalose and backbone DNA formed the largest number of hydrogen bonds and thus constituted the major effect of structural protection for DNA. The number of hydrogen bonds formed by each OH group of trehalose with the backbone DNA was compared. Different types of trehalose-DNA interactions were analyzed, with no prevalent pattern recognized. Diffusion constants for trehalose and water were also calculated, suggesting a glassy/viscose state of the simulation system. It is believed that trehalose protects DNA in the dry state through the network of hydrogen bonds built by the sugars, which reduces the structural fluctuations of DNA and prevents its denaturation.

Fu, Xuebing

2008-08-01T23:59:59.000Z

353

Molecular dynamics simulations of ion range profiles for heavy ions in light targets  

SciTech Connect

The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion–solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

Lan, C.; Xue, J. M.; Zhang, Y.; Morris, J. R.; Zhu, Zh.; Gao, Yanfei; Wang, Y. G.; Yan, S.; Weber, William

2012-01-01T23:59:59.000Z

354

Molecular dynamics simulations of ion range profiles for heavy ions in light targets  

SciTech Connect

The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (< {approx} 25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

Lan, Chune [Peking University; Xue, Jianming [Peking University; Zhang, Yanwen [ORNL; Morris, James R [ORNL; Zhu, Zihua [Pacific Northwest National Laboratory (PNNL); Gao, Yuan [Peking University; Wang, Yugang [Peking University; Yan, Sha [Peking University; Weber, William J [ORNL

2012-01-01T23:59:59.000Z

355

Molecular dynamics simulations of ion range profiles for heavy ions in light targets  

SciTech Connect

The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (<25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

Lan, Chune; Xue, Jianming; Zhang, Yanwen; Morris, James R.; Zhu, Zihua; Gao, Yuan; Wang, Yugang; Yan, Sha; Weber, William J.

2012-09-01T23:59:59.000Z

356

Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Chloride Salts  

E-Print Network (OSTI)

The Accelerator Research Laboratory at Texas A&M is proposing a design for accelerator-driven subcritical fission in molten salt (ADSMS), a system that destroys the transuranic elements in used nuclear fuel. The transuranics (TRU) are the most enduring hazard of nuclear power. TRU contain high radiotoxicity and have half-lives of a thousand to a million years. The ADSMS core is fueled by a homogeneous chloride-based molten salt mixture containing TRUCl3 and NaCl. Certain thermodynamic properties are critical to modeling both the neutronics and heat transfer of an ADSMS system. There is a lack of experimental data on the density, heat capacity, electrical and thermal conductivities, and viscosity of TRUCl3 salt systems. Molecular dynamics simulations using a polarizable ion model (PIM) are employed to determine the density and heat capacity of these melts as a function of temperature. Green-Kubo methods are implemented to calculate the electrical conductivity, thermal conductivity, and viscosity of the salt using the outputs of the simulations. Results for pure molten salt systems are compared to experimental data when possible to validate the potentials used. Here I discuss chloride salt systems of interest, their calculated properties, and possible sources of error for our simulations.

Baty, Austin Alan

2013-05-01T23:59:59.000Z

357

Computational Fluid Dynamic Analysis of the VHTR Lower Plenum Standard Problem  

DOE Green Energy (OSTI)

The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from 450 ºC to perhaps 1000 ºC. While computational fluid dynamics (CFD) has not been used for past safety analysis for nuclear reactors in the U. S., it is being considered for safety analysis for existing and future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal and accident operational situations. To this end, experimental data have been obtained in a scaled model of a narrow slice of the lower plenum of a prismatic VHTR. The present report presents results of CFD examinations of these data to explore potential issues with the geometry, the initial conditions, the flow dynamics and the data needed to fully specify the inlet and boundary conditions; results for several turbulence models are examined. Issues are addressed and recommendations about the data are made.

Richard W. Johnson; Richard R. Schultz

2009-07-01T23:59:59.000Z

358

COMPUTATIONAL FLUID DYNAMICS MODELING ANALYSIS OF COMBUSTORS  

DOE Green Energy (OSTI)

In the current fiscal year FY01, several CFD simulations were conducted to investigate the effects of moisture in biomass/coal, particle injection locations, and flow parameters on carbon burnout and NO{sub x} inside a 150 MW GEEZER industrial boiler. Various simulations were designed to predict the suitability of biomass cofiring in coal combustors, and to explore the possibility of using biomass as a reburning fuel to reduce NO{sub x}. Some additional CFD simulations were also conducted on CERF combustor to examine the combustion characteristics of pulverized coal in enriched O{sub 2}/CO{sub 2} environments. Most of the CFD models available in the literature treat particles to be point masses with uniform temperature inside the particles. This isothermal condition may not be suitable for larger biomass particles. To this end, a stand alone program was developed from the first principles to account for heat conduction from the surface of the particle to its center. It is envisaged that the recently developed non-isothermal stand alone module will be integrated with the Fluent solver during next fiscal year to accurately predict the carbon burnout from larger biomass particles. Anisotropy in heat transfer in radial and axial will be explored using different conductivities in radial and axial directions. The above models will be validated/tested on various fullscale industrial boilers. The current NO{sub x} modules will be modified to account for local CH, CH{sub 2}, and CH{sub 3} radicals chemistry, currently it is based on global chemistry. It may also be worth exploring the effect of enriched O{sub 2}/CO{sub 2} environment on carbon burnout and NO{sub x} concentration. The research objective of this study is to develop a 3-Dimensional Combustor Model for Biomass Co-firing and reburning applications using the Fluent Computational Fluid Dynamics Code.

Mathur, M.P.; Freeman, Mark (U.S. DOE National Energy Technology Laboratory); Gera, Dinesh (Fluent, Inc.)

2001-11-06T23:59:59.000Z

359

Towards the Integration of APECS and VE-Suite for Virtual Power Plant Co-Simulation  

SciTech Connect

Process modeling and simulation tools are widely used for the design and operation of advanced power generation systems. These tools enable engineers to solve the critical process systems engineering problems that arise throughout the lifecycle of a power plant, such as designing a new process, troubleshooting a process unit or optimizing operations of the full process. To analyze the impact of complex thermal and fluid flow phenomena on overall power plant performance, the Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has developed the Advanced Process Engineering Co-Simulator (APECS). The APECS system is an integrated software suite that combines process simulation (e.g., Aspen Plus) and high-fidelity equipment simulations such as those based on computational fluid dynamics (CFD), together with advanced analysis capabilities including case studies, sensitivity analysis, stochastic simulation for risk/uncertainty analysis, and multi-objective optimization. In this paper we discuss the initial phases of the integration of the APECS system with the immersive and interactive virtual engineering software, VE-Suite, developed at Iowa State University and Ames Laboratory. VE-Suite uses the ActiveX (OLE Automation) controls in the Aspen Plus process simulator wrapped by the CASI library developed by Reaction Engineering International to run process/CFD co-simulations and query for results. This integration represents a necessary step in the development of virtual power plant co-simulations that will ultimately reduce the time, cost, and technical risk of developing advanced power generation systems.

Zitney, S.E.; McCorkle, D. (Iowa State University, Ames, IA); Yang, C. (Reaction Engineering International, Salt Lake City, UT); Jordan, T.; Swensen, D. (Reaction Engineering International, Salt Lake City, UT); Bryden, M. (Iowa State University, Ames, IA)

2007-05-01T23:59:59.000Z

360

Simulating soil C dynamics with EPIC: Model description and testing against long-term data  

SciTech Connect

Soil carbon sequestration (SCS) has emerged as a technology with significant potential to help stabilize atmospheric CO2 concentrations and thus reduce the threat of global warming. Methods and models are needed to evaluate and recommend SCS practices based on their effects on carbon dynamics and environmental quality. EPIC (Environment Policy Integrated Climate) is a widely used and tested model for simulating many agroecosystem processes including plant growth, crop yield, tillage, wind and water erosion, runoff, soil density, and leaching. Here we describe new C and N modules developed in EPIC built on concepts from the Century model to connect the simulation of soil C dynamics to crop management, tillage methods, and erosion processes. The added C and N routines interact directly with soil moisture, temperature, erosion, tillage, soil density, leaching, and translocation functions in EPIC. Equations were also added to describe the effects of soil texture on soil C stabilization. Lignin concentration is modeled as a sigmoidal function of plant age. EPIC was tested against data from a Conservation Reserve Program (CRP) 6-yr experiment at five sites in three U.S. Great Plains states and a 61-y long-term agronomic experiment in Canada. Mean Square Deviations (MSD) calculated for CRP sites were less than 0.01 kg C2 m2, except for one site where it reached 0.025 kg2 C2 m. MSD values in the 61-y experiment ranged between 0.047 and 0.077 kg C2 m2. In conclusion, the version of the EPIC model presented and tested here contains the necessary algorithms to simulate SCS and improve understanding of the interactions among soil erosion, C dynamics, and tillage. A strength of the model as tested is its ability to explain the variability in crop production, C inputs and SOC and N cycling over a wised range soil, cropping and climatic conditions over periods from 6 to 61 years. For example, at the Breton site over 61 years, EPIC accounted for 69% of the variability in grain yields, 89 % of the variability in C inputs and 91 % of the variability in SOC content in the top 15 cm. Continued development is be needed is in understanding why it overpredicts at low SOC and underpredicts at high SOC. Possibilities now exit to connect the C and N cycling parts of EPIC to algorithms to describe denitrification as driven by C metabolism and oxygen availability.

Izaurralde, R Cesar C.; Williams, Jimmy R.; Mcgill, William B.; Rosenberg, Norman J.; Quiroga Jakas, Maria C.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamics cfd simulations" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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361

Effects of confinement on water structure and dynamics and on proton transport: a molecular simulation study  

E-Print Network (OSTI)

Classical molecular dynamics (MD) simulations are performed to study structural and dynamic properties of water confined within graphite surfaces. The surfaces are separated at distances varying between 7 and 14.5 Å and the water density is held constant at 1g/cc. Results at 298 K show the formation of a well-ordered structure constituted by water layers parallel to the graphite surfaces. The water molecules in the layers in contact with the surface have a tendency to orient their dipole parallel to the surface. Such ice-like structures may have different structural and dynamic properties than those of ice. The calculated mean square displacement reveals that the mobilities of the confined water at a separation of 8 Å become similar to that of low-temperature water (213 K) at the same density, although the structures of water are very different. The temperature at which the mobility of water confined at the separation of 7 Å would become similar to that of bulk low-temperature water was found to be 373K. With respect to the dynamics of confined water, a significant blue shift is observed in the intermolecular vibrational modes associated with the O×××O×××O bending and O×××O stretching of molecules linked by hydrogen bonds. The analysis of the geometry of water clusters confined between two graphite surfaces has been performed using ab initio methods. The ab initio calculations yield two preferential orientations of water molecules which are; 1) one O-H bond points to the surface and the other is parallel; 2) both O-H bonds are parallel to the surface. These orientations agree with those found in our MD simulation results. The calculated energy barriers for proton transfer of the confined H3O+-(H2O) complexes between two graphite model surfaces suggest that the confinement enhances the proton transfer at the separation 6-14.5 Å. When the confinement is high, at a separation of 4 Å, the barrier energies are extremely large. The confinement does not enhance proton transfer when the H3O+-(H2O) complexes are located further from the surfaces by more than 8 Å. As a result, the barrier energies start to increase at the separation of 20 Å.

Hirunsit, Pussana

2007-05-01T23:59:59.000Z

362

A CFD-based wind solver for a fast response transport and dispersion model  

SciTech Connect

In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.

Gowardhan, Akshay A [Los Alamos National Laboratory; Brown, Michael J [Los Alamos National Laboratory; Pardyjak, Eric R [UNIV OF UTAH; Senocak, Inanc [BOISE STATE UNIV

2010-01-01T23:59:59.000Z

363

Ultrapdeep water blowouts: COMASim dynamic kill simulator validation and best practices recommendations  

E-Print Network (OSTI)

The petroleum industry is in a constant state of change. Few industries have advanced as far technologically as the petroleum industry has in its relatively brief existence. The produced products in the oil and gas industry are finite. As such, the easier to find and produce hydrocarbons are exploited first. This forces the industry to enter new areas and environments to continue supplying the world's hydrocarbons. Many of these new frontiers are in what is considered ultradeep waters, 5000 feet or more of water. While all areas of the oil and gas industry have advanced their ultradeep water technology, one area has had to remain at the forefront: drilling. Unfortunately, while drilling as a whole may be advancing to keep up with these environments, some segments lag behind. Blowout control is one of these areas developed as an afterthought. This lax attitude towards blowouts does not mean they are not a major concern. A blowout can mean injury or loss of life for rig personnel, as well as large economic losses, environmental damage and damage to the oil or gas reservoir itself. Obviously, up-to-date technology and techniques for the prevention and control of ultradeep water blowouts would be an invaluable part of any oil and gas company's exploration planning and technology suite. To further the development of blowout prevention and control, COMASim Cherokee Offshore, MMS, Texas A&M Simulator) was developed. COMASim simulates the planning and execution of a dynamic kill delivered to a blowout. Through a series of over 800 simulation runs, we were able to find several key trends in both the initial conditions as well as the kill requirements. The final phase of this study included a brief review of current industry deepwater well control best practices and how the COMASim results fit in with them. Overall, this study resulted in a better understanding of ultradeep water blowouts and what takes to control them dynamically. In addition to this understanding of blowouts, COMASim's strengths and weaknesses have now been exposed in order to further develop this simulator for industry use.

Noynaert, Samuel F.

2004-12-01T23:59:59.000Z

364

A simple and effective Verlet-type algorithm for simulating Langevin dynamics  

E-Print Network (OSTI)

We present a revision to the well known Stormer-Verlet algorithm for simulating second order differential equations. The revision addresses the inclusion of linear friction with associated stochastic noise, and we analytically demonstrate that the new algorithm correctly reproduces diffusive behavior of a particle in a flat potential. For a harmonic oscillator, our algorithm provides the exact Boltzmann distribution for any value of damping, frequency, and time step for both underdamped and over damped behavior within the usual the stability limit of the Verlet algorithm. Given the structure and simplicity of the method we conclude this approach can trivially be adapted for contemporary applications, including molecular dynamics with extensions such as molecular constraints.

Grønbech-Jensen, Niels

2013-01-01T23:59:59.000Z

365

A simple and effective Verlet-type algorithm for simulating Langevin dynamics  

E-Print Network (OSTI)

We present a revision to the well known Stormer-Verlet algorithm for simulating second order differential equations. The revision addresses the inclusion of linear friction with associated stochastic noise, and we analytically demonstrate that the new algorithm correctly reproduces diffusive behavior of a particle in a flat potential. For a harmonic oscillator, our algorithm provides the exact Boltzmann distribution for any value of damping, frequency, and time step for both underdamped and over damped behavior within the usual the stability limit of the Verlet algorithm. Given the structure and simplicity of the method we conclude this approach can trivially be adapted for contemporary applications, including molecular dynamics with extensions such as molecular constraints.

Niels Grønbech-Jensen; Oded Farago

2012-12-06T23:59:59.000Z

366

Dynamic Monte Carlo simulation of coupled transport through a narrow multiply-occupied pore  

E-Print Network (OSTI)

Dynamic Monte Carlo simulations are used to study coupled transport (co-transport) through sub-nanometer-diameter pores. In this classic Hodgkin-Keynes mechanism, an ion species uses the large flux of an abundant ion species to move against its concentration gradient. The efficiency of co-transport is examined for various pore parameters so that synthetic nanopores can be engineered to maximize this effect. In general, the pore must be narrow enough that ions cannot pass each other and the charge of the pore large enough to attract many ions so that they exchange momentum. Co-transport efficiency increases as pore length increases, but even very short pores exhibit co-transport, in contradiction to the usual perception that long pores are necessary. The parameter ranges where co-transport occurs is consistent with current and near-future synthetic nanopore geometry parameters, suggesting that co-transport of ions may be a new application of nanopores.

Dezs? Boda; Éva Csányi; Dirk Gillespie; Tamás Kristóf

2013-10-08T23:59:59.000Z

367

High-precision molecular dynamics simulation of UO2-PuO2: pair potentials comparison  

E-Print Network (OSTI)

Our series of articles is devoted to high-precision molecular dynamics simulation of mixed actinide-oxide (MOX) fuel in the rigid ions approximation using high-performance graphics processors (GPU). In the first article we assess 10 most relevant interatomic sets of pair potentials (SPP) by reproduction of solid phase properties of uranium dioxide (UO2) - temperature dependences of the lattice constant, bulk modulus, enthalpy and heat capacity. Measurements were performed with 1K accuracy in a wide temperature range from 300K up to melting point. The best results are demonstrated by two recent SPPs MOX-07 and Yakub-09, which both had been fitted to the recommended thermal expansion in the range of temperatures 300-3100K. Compared with them, the widely used SPPs Basak-03 and Morelon-03 reproduce the experimental data noticeably worse at temperatures above 2500K.

Potashnikov, S I; Nekrasov, K A; Kupryazhkin, A Ya

2011-01-01T23:59:59.000Z

368

Molecular dynamics simulation of interaction of H with vacancy in W  

DOE Green Energy (OSTI)

Molecular dynamics simulations were performed to investigate the interaction between H and vacancy in W using an analytical bond-order potential to describe the interactions between W-W, W-H and H-H. The most stable configuration for H in W is the tetrahedron interstitial site. We calculated the binding energies of an H and a vacancy to an H-vacancy cluster (HnVm) in W, respectively, where n and m ranged from 0 to 10. The binding energy was almost unchanged. The binding energy of a vacancy to H-vacancy cluster is about 0.4eV, which is higher than the binding energy of an H to H-vacancy cluster. Vacancy is much easier to binding with H-vacancy cluster than H. And H is easier to stay in the tetrahedron interstitial site or octahedron interstitial site in bcc W.

Li, Xiaochun; Gao, Fei; Lu, Guang-Hong

2009-09-15T23:59:59.000Z

369

Three dimensional analysis of turbulent steam jets in enclosed structures : a CFD approach.  

SciTech Connect

This paper compares the three-dimensional numerical simulation with the experimental data of a steam blowdown event in a light water reactor containment building. The temperature and pressure data of a steam blowdown event was measured at the Purdue University Multi-Dimensional Integrated Test Assembly (PUMA), a scaled model of the General Electric simplified Boiling Water Reactor. A three step approach was used to analyze the steam jet behavior. First, a 1-Dimensional, system level RELAP5/Mod3.2 model of the steam blowdown event was created and the results used to set the initial conditions for the PUMA blowdown experiments. Second, 2-Dimensional CFD models of the discharged steam jets were computed using PHOENICS, a commercially available CFD package. Finally, 3-Dimensional model of the PUMA drywell was created with the boundary conditions based on experimental measurements. The results of the 1-D and 2-D models were reported in the previous meeting. This paper discusses in detail the formulation and the results of the 3-Dimensional PHOENICS model of the PUMA drywell. It is found that the 3-D CFD solutions compared extremely well with the measured data.

Ishii, M.; NguyenLe, Q.

1999-04-20T23:59:59.000Z

370

Towards CFD Modelling of Critical Heat Flux in Fuel Rod Bundles  

SciTech Connect

The paper describes actual CFD approaches to subcooled boiling and investigates their capability to contribute to fuel assembly design. In a prototype version of the CFD code CFX a wall boiling model is implemented based on a wall heat flux partition algorithm. It can be shown, that the wall boiling model is able, to calculate the cross sectional averaged vapour volume fraction with good agreement to published measurements. The most sensitive parameters of the model are identified. Needs for more detailed experiments are established which are necessary to support further model development. Nevertheless in the paper the model is applied for the investigation of the phenomena inside a hot channel in a fuel assembly. Here the essential parameter is the critical heat flux. Although subcooled boiling represents only a preliminary state toward critical heat flux essential parameters like the swirl, the cross flow between adjacent channels and concentration regions of bubbles can be determined. By calculating the temperature at the rod surface the critical regions can be identified which might later on lead to departure from nucleate boiling and possible damage of the fuel pin. The application of up-to-date CFD with a subcooled boiling model for the simulation of a hot channel enables the comparison and the evaluation of different geometrical designs of the spacer grids of a fuel rod bundle. (authors)

Krepper, Eckhard [Forschungszentrum Rossendorf e.V., Institute of Safety Research, D-01314 Dresden, POB 510119 (Germany); Egorov, Yury [ANSYS Germany GmbH Staudenfeldweg 12, D-83624 Otterfing (Germany); Koncar, Bostjan ['Jozef Stefan' Institute Jamova 39, 1000 Ljubljana (Slovenia)

2006-07-01T23:59:59.000Z

371

A combined Event-Driven/Time-Driven molecular dynamics algorithm for the simulation of shock waves in rarefied gases  

Science Conference Proceedings (OSTI)

A novel combined Event-Driven/Time-Driven (ED/TD) algorithm to speed-up the Molecular Dynamics simulation of rarefied gases using realistic spherically symmetric soft potentials is presented. Due to the low density regime, the proposed method correctly ... Keywords: 47.11.Mn, 47.40.Ki, 47.45.-n, 47.61.Cb, Event-Driven MD, Molecular Dynamics, Non-continuum effects, Shock Waves

Paolo Valentini; Thomas E. Schwartzentruber

2009-12-01T23:59:59.000Z

372

Plant-wide dynamic simulation of an IGCC plant with CO2 capture  

Science Conference Proceedings (OSTI)

To eliminate the harmful effects of greenhouse gases, especially that of CO2, future coalfired power plants need to consider the option for CO2 capture. The loss in efficiency for CO2 capture is less in an Integrated Gasification Combined Cycle (IGCC) plant compared to other conventional coal combustion processes. However, no IGCC plant with CO2 capture currently exists in the world. Therefore, it is important to consider the operability and controllability issues of such a plant before it is commercially built. With this objective in mind, a detailed plant-wide dynamic simulation of an IGCC plant with CO2 capture has been developed. The plant considers a General Electric Energy (GEE)-type downflow radiant-only gasifier followed by a quench section. A two-stage water gas shift (WGS) reaction is considered for conversion of about 96 mol% of CO to CO2. A two-stage acid gas removal (AGR) process based on a physical solvent is simulated for selective capture of H2S and CO2. The clean syngas is sent to a gas turbine (GT) followed by a heat recovery steam generator (HRSG). The steady state results are validated with data from a commercial gasifier. A 5 % ramp increase in the flowrate of coal is introduced to study the system dynamics. To control the conversion of CO at a desired level in the WGS reactors, the steam/CO ratio is manipulated. This strategy is found to be efficient for this operating condition. In the absence of an efficient control strategy in the AGR process, the environmental emissions exceeded the limits by a great extent.

Bhattacharyya, D.; Turton, R.; Zitney, S.

2009-01-01T23:59:59.000Z

373

A comparison of crystalline and molten structures of zirconolite (CaZrTi?O?), a potential plutonium wasteform medium, by molecular dynamics simulation and topological analysis  

E-Print Network (OSTI)

Molecular dynamics simulations of the ceramic compound zirconolite (CaZrTi?O?), a potential crystalline wasteform host for plutonium, were carried out for ideal and experimental crystalline forms and a simulated molten ...

Rich, Sarah Celeste

2008-01-01T23:59:59.000Z

374

Evaluation of a CCSM3 Simulation with a Finite Volume Dynamical Core for the Atmosphere at 1° Latitude × 1.25° Longitude Resolution  

Science Conference Proceedings (OSTI)

A simulation of the present-day climate by the Community Climate System Model version 3 (CCSM3) that uses a Finite Volume (FV) numerical method for solving the equations governing the atmospheric dynamics is presented. The simulation is compared ...

G. Bala; R. B. Rood; A. Mirin; J. McClean; Krishna Achutarao; D. Bader; P. Gleckler; R. Neale; P. Rasch

2008-04-01T23:59:59.000Z

375

Experiment and Simulation of Dynamic Voltage Regulation in Multiple Distributed Energy Resources Systems  

Science Conference Proceedings (OSTI)

Distributed energy (DE) resources are power sources located near load centers and equipped with power electronics converters to interface with the grid, therefore it is feasible for DE to provide reactive power (along with active power) locally for dynamic voltage regulation. In this paper, a synchronous condenser and a microturbine with an inverter interface are implemented in parallel in a distribution system to regulate the local voltage. Developed voltage control schemes for the inverter and the synchronous condenser are presented. Experimental results show that both the inverter and the synchronous condenser can regulate the local voltage instantaneously although the dynamic response of the inverter is much faster than the synchronous condenser. In a system with multiple DEs performing local voltage regulation, the interaction between the DEs is studied. The simulation results show the relationship between the voltages in the system and the reactive power required for the voltage regulation. Also, integrated voltage regulation (multiple DEs performing voltage regulation) can increase the voltage regulation capability of DEs and reduce the capital and operating costs.

Xu, Yan [ORNL; Li, Fangxing [ORNL; Kueck, John D [ORNL; Rizy, D Tom [ORNL

2007-01-01T23:59:59.000Z

376

Molecular Dynamics Simulation of Tri-n-Butyl-Phophate Liquid: A Force Field Comparative Study  

SciTech Connect

Molecular dynamics (MD) simulations were conducted to compare the performance of four force fields in predicting thermophysical properties of tri-n-butyl-phosphate (TBP) in the liquid phase. The intramolecular force parameters used were from the Assisted Model Building with Energy Refinement (AMBER) force field model. The van der Waals parameters were based on either the AMBER or the Optimized Potential for Liquid Simulation (OPLS) force fields. The atomic partial charges were either assigned by performing quantum chemistry calculations or utilized previously published data, and were scaled to approximate the average experimental value of the electric dipole moment. Canonical ensemble computations based on the aforementioned parameters were performed near the atmospheric pressure and temperature to obtain the electric dipole moment, mass density, and self-diffusion coefficient. In addition, the microscopic structure of the liquid was characterized via pair correlation functions between selected atoms. It has been demonstrated that the electric dipole moment can be approximated within 1% of the average experimental value by virtue of scaled atomic partial charges. The liquid mass density can be predicted within 0.5-1% of its experimentally determined value when using the corresponding charge scaling. However, in all cases the predicted self- diffusion coefficient is significantly smaller than a commonly quoted experimental measurement; this result is qualified by the fact that the uncertainty of the experimental value was not available.

Cui, Shengting [ORNL; de Almeida, Valmor F [ORNL; Hay, Benjamin [ORNL; Ye, Xianggui [ORNL; Khomami, Bamin [ORNL

2012-01-01T23:59:59.000Z

377

Dynamic Modeling and Simulation Based Analysis of an Ammonia Borane (AB) Reactor System for Hydrogen Storage  

DOE Green Energy (OSTI)

Research on ammonia borane (AB, NH3BH3) has shown it to be a promising material for chemical hydrogen storage in PEM fuel cell applications. AB was selected by DOE’s Hydrogen Storage Engineering Center of Excellence (HSECoE) as the initial chemical hydride of study because of its high hydrogen storage capacity (up to 19.6% by weight for the release of three molar equivalents of hydrogen gas) and its stability under typical ambient conditions. A model of a bead reactor system which includes feed and product tanks, hot and cold augers, a ballast tank/reactor, a H2 burner and a radiator was developed to study AB system performance in an automotive application and estimate the energy, mass, and volume requirements for this off-board regenerable hydrogen storage material. Preliminary system simulation results for a start-up case and for a transient drive cycle indicate appropriate trends in the reactor system dynamics. A new controller was developed and validated in simulation for a couple of H2 demand cases.

Devarakonda, Maruthi N.; Holladay, Jamelyn D.; Brooks, Kriston P.; Rassat, Scot D.; Herling, Darrell R.

2010-10-02T23:59:59.000Z

378

Non-Fourier heat conduction in a single-walled carbon nanotube: Classical molecular dynamics simulations  

SciTech Connect

Nonstationary heat conduction in a single-walled carbon nanotube was investigated by applying a local heat pulse with duration of subpicoseconds. The investigation was based on classical molecular dynamics simulations, where the heat pulse was generated as coherent fluctuations by connecting a thermostat to the local cell for a short duration. The heat conduction through the nanotube was observed in terms of spatiotemporal temperature profiles. Results of the simulations exhibit non-Fourier heat conduction where a distinct amount of heat is transported in a wavelike form. The geometry of carbon nanotubes allows us to observe such a phenomenon in the actual scale of the material. The resulting spatiotemporal profile was compared with the available macroscopic equations, the so-called non-Fourier heat conduction equations, in order to investigate the applicability of the phenomenological models to a quasi-one-dimensional system. The conventional hyperbolic diffusion equation fails to predict the heat conduction due to the lack of local diffusion. It is shown that this can be remedied by adopting a model with dual relaxation time. Further modal analyses using wavelet transformations reveal a significant contribution of the optical phonon modes to the observed wavelike heat conduction. The result suggests that, in carbon nanotubes with finite length where the long-wavelength acoustic phonons behave ballistically, even optical phonons can play a major role in the non-Fourier heat conduction.

Shiomi, Junichiro; Maruyama, Shigeo [Department of Mechanical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2006-05-15T23:59:59.000Z

379

Package Equivalent Reactor Networks as Reduced Order Models for Use with CAPE-OPEN Compliant Simulation  

SciTech Connect

Engineering simulations of coal gasifiers are typically performed using computational fluid dynamics (CFD) software, where a 3-D representation of the gasifier equipment is used to model the fluid flow in the gasifier and source terms from the coal gasification process are captured using discrete-phase model source terms. Simulations using this approach can be very time consuming, making it difficult to imbed such models into overall system simulations for plant design and optimization. For such system-level designs, process flowsheet software is typically used, such as Aspen Plus® [1], where each component where each component is modeled using a reduced-order model. For advanced power-generation systems, such as integrated gasifier/gas-turbine combined-cycle systems (IGCC), the critical components determining overall process efficiency and emissions are usually the gasifier and combustor. Providing more accurate and more computationally efficient reduced-order models for these components, then, enables much more effective plant-level design optimization and design for control. Based on the CHEMKIN-PRO and ENERGICO software, we have developed an automated methodology for generating an advanced form of reduced-order model for gasifiers and combustors. The reducedorder model offers representation of key unit operations in flowsheet simulations, while allowing simulation that is fast enough to be used in iterative flowsheet calculations. Using high-fidelity fluiddynamics models as input, Reaction Design’s ENERGICO® [2] software can automatically extract equivalent reactor networks (ERNs) from a CFD solution. For the advanced reduced-order concept, we introduce into the ERN a much more detailed kinetics model than can be included practically in the CFD simulation. The state-of-the-art chemistry solver technology within CHEMKIN-PRO allows that to be accomplished while still maintaining a very fast model turn-around time. In this way, the ERN becomes the basis for high-fidelity kinetics simulation, while maintaining the spatial information derived from the geometrically faithful CFD model. The reduced-order models are generated in such a way that they can be easily imported into a process flowsheet simulator, using the CAPE-OPEN architecture for unit operations. The ENERGICO/CHEMKIN-PRO software produces an ERN-definition file that is read by a dynamically linked library (DLL) that can be easily linked to any CAPE-OPEN compliant software. The plug-in unitoperation module has been successfully demonstrated for complex ERNs of coal gasifiers, using both Aspen Plus and COFE process flowsheet simulators through this published CAPE-OPEN interface.

Meeks, E.; Chou, C. -P.; Garratt, T.

2013-03-31T23:59:59.000Z

380

Phase Field Simulations  

Science Conference Proceedings (OSTI)

Mar 6, 2013 ... The anisotropic solid-vapor surface energy for a 2D PFC hexagonal crystal is ... Finally, we examine the dynamic case of step-flow growth of a crystal into ... Thermal and Dispersed-Phase Analysis of Nano Fluid Using CFD-A Hybrid ... gas turbine power generation systems because of its high melting point, ...

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


381

CFD Simulation of Anode Bubble Behavior in Aluminum Reduction ...  

Science Conference Proceedings (OSTI)

Cryoscopic Data for Hall-Héroult Bath Containing Magnesium Fluoride, Calcium Fluoride, Potassium Cryolite, and Sodium Chloride · Current Distribution and ...

382

Simulation of shock-induced melting of Ni using molecular dynamics coupled to a two-temperature model  

E-Print Network (OSTI)

Simulation of shock-induced melting of Ni using molecular dynamics coupled to a two-temperature and electron-phonon coupling, Pmelt and Tmelt change. For a given pressure, the temperature behind the shock conduction and electron-phonon coupling. The decrease in the temperature behind the shock front is enhanced

Zhigilei, Leonid V.

383

Molecular Dynamics Simulation of Phase-Change of Water inside a SWNT Shigeo Maruyama, Tatsuto Kimura and Yasuhiro Igarashi  

E-Print Network (OSTI)

, Bunkyo-ku, Tokyo 113-8656, Japan The phase change of liquid water to ice crystal inside a singleMolecular Dynamics Simulation of Phase-Change of Water inside a SWNT Shigeo Maruyama, Tatsuto, the carbon atoms were cooled at the constant heat-removal rate. The phase change phenomena with various rates

Maruyama, Shigeo

384

Modular Modeling System (MMS): A Code for the Dynamic Simulation of Fossil and Nuclear Power Plants, Volume 2: Programmer's Manual  

Science Conference Proceedings (OSTI)

Now complete and fully documented, the MMS code is available for the dynamic simulation of both fossil-fired and nuclear power plants. The broad range of applications, from troubleshooting new designs to analysis of startup tests, has made this easy-to use code a utility standard since its first-stage release in 1983.

1987-05-01T23:59:59.000Z

385

Modular Modeling System (MMS): A Code for the Dynamic Simulation of Fossil and Nuclear Power Plants, Volume 1: Theory Manual  

Science Conference Proceedings (OSTI)

Now complete and fully documented, the MMS code is available for the dynamic simulation of both fossil-fired and nuclear power plants. The broad range of applications, from troubleshooting new designs to analysis of startup tests, has made this easy-to use code a utility standard since its first-stage release in 1983.

1987-04-01T23:59:59.000Z

386

Numerical simulation of four-field extended magnetohydrodynamics in dynamically adaptive curvilinear coordinates via Newton-Krylov-Schwarz  

Science Conference Proceedings (OSTI)

Numerical simulations of the four-field extended magnetohydrodynamics (MHD) equations with hyper-resistivity terms present a difficult challenge because of demanding spatial resolution requirements. A time-dependent sequence of r-refinement adaptive ... Keywords: Dynamically adaptive grid, Equidistribution principle, MHD, Magnetic reconnection, Monge-Ampère equation, Monge-Kantorovich optimization, NKS, Structured grid, r-Refinement

Xuefei Yuan; Stephen C. Jardin; David E. Keyes

2012-07-01T23:59:59.000Z

387

Benchmark of the IMPACT Code for High Intensity Beam Dynamics Simulation  

E-Print Network (OSTI)

of Beam Dynamics in the SNS Linac," Nuclear Instruments andto study beam dynamics in the SNS linac, the J-PARC linac

Qiang, J.; Ryne, R.D.

2008-01-01T23:59:59.000Z

388

Modeling HCCI using CFD and Detailed Chemistry with Experimental Validation and a Focus on CO Emissions  

DOE Green Energy (OSTI)

Multi-zone CFD simulations with detailed kinetics were used to model engine experiments performed on a diesel engine that was converted for single cylinder, HCCI operation, here using iso-octane as the fuel. The modeling goals were to validate the method (multi-zone combustion modeling) and the reaction mechanism (LLNL 857 species iso-octane), both of which performed very well. The purpose of this paper is to document the validation findings and to set the ground work for further analysis of the results by first looking at CO emissions characteristics with varying equivalence ratio.

Hessel, R; Foster, D; Aceves, S; Flowers, D; Pitz, B; Dec, J; Sjoberg, M; Babajimopoulos, A

2007-04-23T23:59:59.000Z

389

Organization of IGCC processes with reduced order CFD models  

SciTech Connect

Integrated gasificationcombinedcycle(IGCC)plantshavesignificantadvantagesforefficientpowergen- eration withcarboncapture.Moreover,withthedevelopmentofaccurateCFDmodelsforgasificationand combined cyclecombustion,keyunitsoftheseprocessescannowbemodeledmoreaccurately.However, the integrationofCFDmodelswithinsteady-stateprocesssimulators,andsubsequentoptimizationof the integratedsystem,stillpresentssignificantchallenges.Thisstudydescribesthedevelopmentand demonstration ofareducedordermodeling(ROM)frameworkforthesetasks.Theapproachbuildson the conceptsofco-simulationandROMdevelopmentforprocessunitsdescribedinearlierstudies.Here we showhowtheROMsderivedfrombothgasificationandcombustionunitscanbeintegratedwithin an equation-orientedsimulationenvironmentfortheoveralloptimizationofanIGCCprocess.Inaddi- tion toasystematicapproachtoROMdevelopment,theapproachincludesvalidationtasksfortheCFD model aswellasclosed-looptestsfortheintegratedflowsheet.Thisapproachallowstheapplicationof equation-based nonlinearprogrammingalgorithmsandleadstofastoptimizationofCFD-basedprocess flowsheets. TheapproachisillustratedontwoflowsheetsbasedonIGCCtechnology.

Lang, Y.; Zitney, S.; Biegler, L.

2011-01-01T23:59:59.000Z

390

A Robust Four-Fluid Transient Flow Simulator as an Analysis and Decision Making Tool for Dynamic Kill Operation  

E-Print Network (OSTI)

The worst scenario of drilling operation is blowout which is uncontrolled flow of formation fluid into the wellbore. Blowouts result in environmental damage with potential risk of injuries and fatalities. Although not all blowouts result in disaster, outcomes of blowouts are unknown and should be studied before starting an operation. Plans should be available to prevent blowouts or provide safe and secure ways of controlling the well before the drilling operation starts. The plan should include procedures in case of any blowout incident as a proactive measure. A few commercial softwares are available in the industry for dynamic kill and transient modeling. All models are proprietary and very complex which reduces the flexibility of the program for specific cases. The purpose of this study is to develop a pseudo transient hydraulic simulator for dynamic kill operations. The idea and concept is to consider the flow of each phase as a single phase flow. The summation of hydrostatic and frictional pressure of each phase determines the bottomhole pressure during the dynamic kill operation. The simulator should be versatile and capable of handling special cases that may encounter during blowouts. Some of the main features of the proposed dynamic kill simulator include; quick and robust simulation, fluid properties are corrected for pressure and temperature, sensitivity analysis can be performed through slide bars, and capable of handling variety of wellbore trajectories. The results from the proposed simulator were compared to the result of commercial software, OLGA ABC. The results were in agreement with each other. It is recommended to apply the simulator for operations with required kill fluid volumes of one to two wellbore volumes.

Haghshenas, Arash

2013-05-01T23:59:59.000Z

391

Modified Nose-Hoover thermostat for solid state for constant temperature molecular dynamics simulation  

SciTech Connect

Nose-Hoover (NH) thermostat methods incorporated with molecular dynamics (MD) simulation have been widely used to simulate the instantaneous system temperature and feedback energy in a canonical ensemble. The method simply relates the kinetic energy to the system temperature via the particles' momenta based on the ideal gas law. However, when used in a tightly bound system such as solids, the method may suffer from deriving a lower system temperature and potentially inducing early breaking of atomic bonds at relatively high temperature due to the neglect of the effect of the potential energy of atoms based on solid state physics. In this paper, a modified NH thermostat method is proposed for solid system. The method takes into account the contribution of phonons by virtue of the vibrational energy of lattice and the zero-point energy, derived based on the Debye theory. Proof of the equivalence of the method and the canonical ensemble is first made. The modified NH thermostat is tested on different gold nanocrystals to characterize their melting point and constant volume specific heat, and also their size and temperature dependence. Results show that the modified NH method can give much more comparable results to both the literature experimental and theoretical data than the standard NH. Most importantly, the present model is the only one, among the six thermostat algorithms under comparison, that can accurately reproduce the experimental data and also the T{sup 3}-law at temperature below the Debye temperature, where the specific heat of a solid at constant volume is proportional to the cube of temperature.

Chen, Wen-Hwa, E-mail: whchen@pme.nthu.edu.tw [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); National Applied Research Laboratories, Taipei 10622, Taiwan, ROC (China); Wu, Chun-Hung [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Cheng, Hsien-Chie [Department of Aerospace and Systems Engineering, Feng Chia University, Taichung 40724, Taiwan (China)

2011-07-10T23:59:59.000Z

392

Computational Fluid Dynamics (CFD) Modelling on Soot Yield for Fire  

E-Print Network (OSTI)

) , CIBSE Guide E(iii) , etc. All design parameters of the smoke control strategy and architectural design Fire Protection Association, Quincy, MA, USA, 2007. iii CIBSE Guide E, Fire Engineering, 2nd Edition

393

European Conference on Computational Fluid Dynamics ECCOMAS CFD 2006  

E-Print Network (OSTI)

will be applied from 2009, it requires a further 80% reduction in PM and a further 20% reduction in NOx. In order. Shimo, M. Kataoka and H. Fujimoto, "Effect of Cooling of Burned Gas by Vertical Vortex on NOx Reduction://www.ifs.tohoku.ac.jp/edge Key words: Diesel Engine, Exhaust emission reduction, Kriging model Abstract. Diesel engine combustion

Obayashi, Shigeru

394

A comparative study of Lotka-Volterra and system dynamics models for simulation of technology industry dynamics  

E-Print Network (OSTI)

Scholars have developed a range of qualitative and quantitative models for generalizing the dynamics of technological innovation and identifying patterns of competition between rivals. This thesis compares two predominant ...

Ünver, Hakk? Özgür

2008-01-01T23:59:59.000Z

395

Molecular dynamics simulation of montmorillonite and mechanical and thermodynamic properties calculations  

E-Print Network (OSTI)

Nanocomposites refer to the materials in which the defining characteristic size of inclusions is in the order of 10-100nm. There are several types of nanoparticle inclusions with different structures: metal clusters, fullerenes particles and molybdenum selenide, Our research focus is on polymer nanocomposites with inorganic clay particles as inclusions, in particular we used sodium montmorillonite polymer nanocomposite. In our study, modeling and simulations of sodium montmorillonite (Na+-MMT) is currently being investigated as an inorganic nanocomposite material. Na+-MMT clay consists of platelets, one nanometer thick with large lateral dimensions, which can be used to achieve efficient reinforcement of polymer matrices. This nanocomposite has different applications such as a binder of animal feed, a plasticizing agent in cement, brick and ceramic, and a thickener and stabilizer of latex and rubber adhesives. In this study, sodium montmorillonite called Na+-MMT structure is built with the bulk system and the layered system which includes from 1 to 12 layers by using Crystal Builder of Cerius2. An isothermal and isobaric ensemble is used for calculation of thermodynamic properties such as specific heat capacities and isothermal expansion coefficients of Na+-MMT. A canonical ensemble which holds a fixed temperature, volume and number of molecules is used for defining exfoliation kinetics of layered structures and surface formation energies for Na+-MMT layered structures are calculated by using a canonical ensemble. Mechanical properties are used to help characterize and identify the Na+-MMT structure. Several elastic properties such as compliance and stiffness matrices, Young's, shear, and bulk modulus, volume compressibility, Poisson's ratios, Lamé constants, and velocities of sound are calculated in specified directions. Another calculation method is the Vienna Ab-initio Simulation Package (VASP). VASP is a complex package for performing ab-initio quantum-mechanical calculations and molecular dynamic (MD) simulations using pseudopotentials and a plane wave basis set. Cut off energy is optimized for the unit cell of Na+-MMT by using different cut off energy values. Experimental and theoretical cell parameters are compared by using cell shape and volume optimization and root mean square (RMS) coordinate difference is calculated for variation of cell parameters. Cell shape and volume optimization are done for calculating optimum expansion or compression constant.

Atilhan, Selma

2007-05-01T23:59:59.000Z

396

Modification of Defect Structures in Graphene by Electron Irradiation: Ab Initio Molecular Dynamics Simulations  

SciTech Connect

Defects play an important role on the unique properties of the sp2-bonded materials, such as graphene. The creation and evolution of mono-vacancy, di-vacancy, Stone-Wales (SW) and grain boundaries (GBs) under irradiation in graphene are investigated using density functional theory and time-dependent density functional theory molecular dynamics simulations. It is of great interest to note that the patterns of these defects can be controlled through electron irradiation. The SW defects can be created by electron irradiation with energy of above the displacement threshold energy (Td, {approx}19 eV) and can be healed with an energy (14-18 eV) lower than Td. The transformation between four types of divacancies, V2(5-8-5), V2(555-777), V2(5555-6-7777), and V2(55-77) can be realized through bond rotation induced by electron irradiation. The migrations of divancancies, SW defects, and GBs can also be controlled by electron irradiation. Thus, electron irradiation can serve as an important tool to modify morphology in a controllable manner, and to tailor the physical properties of graphene.

Wang, Zhiguo; Zhou, Yungang; Bang, Junhyeok; Prange, Micah P.; Zhang, Shengbai; Gao, Fei

2012-08-02T23:59:59.000Z

397

Molecular-dynamics simulation of clustering processes in sea-ice floes  

E-Print Network (OSTI)

In seasonally ice-covered seas and along the margins of perennial ice pack, i.e. in regions with medium ice concentrations, the ice cover typically consists of separate floes interacting with each other by inelastic collisions. In this paper, hitherto unexplored analogies between this type of ice cover and two-dimensional granular gases are used to formulate a model of ice dynamics at the floe level. The model consists of: (i) momentum equations for floe motion between collisions, formulated in the form of a Stokes-flow problem, with floe-size dependent time constant and equilibrium velocity, and (ii) hard-disk collision model. The numerical algorithm developed is suitable for simulating particle-laden flow of $N$ disk-shaped floes with arbitrary size distribution. The model is applied to study clustering phenomena in sea ice with power-law floe-size distribution. In particular, the influence of the average ice concentration $\\bar{A}$ on the formation and characteristics of clusters is analyzed in detail. The...

Herman, Agnieszka

2011-01-01T23:59:59.000Z

398

Molecular dynamics simulations of H{sub 2} adsorption in tetramethyl ammonium lithium phthalocyanine crystalline structures.  

DOE Green Energy (OSTI)

Tetramethyl ammonium lithium phthalocyanine is explored as a potential material for storage of molecular hydrogen. Density functional theory calculations are used to investigate the molecular structure and the dimer conformation. Additional scans performed to determine the interactions of a H{sub 2} molecule located at various distances from the molecular sites are used to generate a simple force field including dipole-induced-dipole interactions. This force field is employed in molecular dynamics simulations to calculate adsorption isotherms at various pressures. The regions of strongest adsorption are quantified as functions of temperature, pressure, and separation between molecules in the adsorbent phase, and compared to the regions of strongest binding energy as given by the proposed force field. It is found that the total adsorption could not be predicted only from the spatial distribution of the strongest binding energies; the available volume is the other contributing factor even if the volume includes regions of much lower binding energy. The results suggest that the complex anion is primarily involved in the adsorption process with molecular hydrogen, whereas the cation serves to provide access for hydrogen adsorption in both sides of the anion molecular plane, and spacing between the planes.

Lamonte, K.; Gomez Gualdron, D.; Scanlon, L. G.; Sandi, G.; Feld, W.; Balbuena, P. B.; Chemical Sciences and Engineering Division; Texas A& M Univ.; Wright-Patterson Air Force Base; Wright State Univ.

2008-11-01T23:59:59.000Z

399

National Ignition Facility computational fluid dynamics modeling and light fixture case studies  

SciTech Connect

This report serves as a guide to the use of computational fluid dynamics (CFD) as a design tool for the National Ignition Facility (NIF) program Title I and Title II design phases at Lawrence Livermore National Laboratory. In particular, this report provides general guidelines on the technical approach to performing and interpreting any and all CFD calculations. In addition, a complete CFD analysis is presented to illustrate these guidelines on a NIF-related thermal problem.

Martin, R.; Bernardin, J.; Parietti, L.; Dennison, B.

1998-02-01T23:59:59.000Z

400

Force-field development and molecular dynamics simulations of ferrocene-peptide conjugates as a scaffold for hydrogenase mimics.  

Science Conference Proceedings (OSTI)

The increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene-peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene-bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide-bioorganometallic chemistry. Using the automated frequency-matching method (AFMM), optimized intramolecular force-field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum-chemically computed electrostatic potentials. The force field was tested against experimental X-ray crystal structures of dipeptide derivatives of ferrocene-1,1{prime}-dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C2-symmetrical intramolecular hydrogen-bonding pattern, that were stable over 0.1{micro}s MD simulations. The crystal packing properties of ferrocene-1-(D)alanine-(D)proline{prime}-1-(D)alanine-(D)proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 s MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni-Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide-based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene-peptides as minimal enzyme mimics.

De Hatten, Xavier [University of Bordeaux; Cournia, Zoe [Yale University; Smith, Jeremy C [ORNL; Metzler-Nolte, Nils [University of Bochum, Germany

2007-08-01T23:59:59.000Z

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401

Force-field development and molecular dynamics simulations of ferrocene-peptide conjugates as a scaffold for hydrogenase mimics  

Science Conference Proceedings (OSTI)

The increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene-peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene-bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide-bioorganometallic chemistry. Using the automated frequency-matching method (AFMM), optimized intramolecular force-field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum-chemically computed electrostatic potentials. The force field was tested against experimental X-ray crystal structures of dipeptide derivatives of ferrocene-1,1'-dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C{sub 2}-symmetrical intramolecular hydrogen-bonding pattern, that were stable over 0.1 {micro}s MD simulations. The crystal packing properties of ferrocene-1-(D)alanine-(D)proline-1'-(D)alanine-(D)proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 {micro}s MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni-Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide-based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene-peptides as minimal enzyme mimics.

De Hatten, Xavier [University of Bordeaux; Cournia, Zoe [Yale University; Smith, Jeremy C [ORNL; Huc, I [University of Bochum, Germany; Metzler-Nolte, Nils [University of Bochum, Germany

2007-08-01T23:59:59.000Z

402

Investigations of the Application of CFD to Flow Expected in the Lower Plenum of the Prismatic VHTR  

Science Conference Proceedings (OSTI)

The Generation IV (Gen IV) very high temperature reactor (VHTR) will either be a prismatic (block) or pebble bed design. However, a prismatic VHTR reference design, based on the General Atomics Gas Turbine-Modular Helium Reactor (GT-MHR) [General Atomics, 1996] has been developed for preliminary analysis purposes [MacDonald, et al., 2003]. Numerical simulation studies reported herein are based on this reference design. In the lower plenum of the prismatic reference design, the flow will be introduced by dozens of turbulent jets from the core above. The jet flow will encounter rows of columns that support the core. The flow from the core will have to turn ninety degrees and flow toward the exit duct as it passed through the forest of support columns. Due to the radial variation of the power density in the core, the jets will be at various temperatures at the inlet to the lower plenum. This presents some concerns, including that local hot spots may occur in the lower plenum. This may have a deleterious effect on the materials present as well as cause a variation in temperature to be present as the flow enters the power conversion system machinery, which could cause problems with the operation of the machinery. In the past, systems analysis codes have been used to model flow in nuclear reactor systems. It is recognized, however, that such codes are not capable of modeling the local physics of the flow to be able to analyze for local mixing and temperature variations. This has led to the determination that computational fluid dynamic (CFD) codes be used, which are generally regarded as having the capability of accurately simulating local flow physics. Accurate flow modeling involves determining appropriate modeling strategies needed to obtain accurate analyses. These include determining the fineness of the grid needed, the required iterative convergence tolerance, which numerical discretization method to use, and which turbulence model and wall treatment should be employed. It also involves validating the computer code and turbulence model against a series of separate and combined flow phenomena and selecting the data used for the validation. This report describes progress made to identify proper modeling strategies for simulating the lower plenum flow for the task entitled “CFD software validation of jets in crossflow,” which was designed to investigate the issues pertaining to the validation process. The flow phenomenon previously chosen to investigate is flow in a staggered tube bank because it is shown by preliminary simulations to be the location of the highest turbulence intensity in the lower plenum Numerical simulations were previously obtained assuming that the flow is steady. Various turbulence models were employed along with strategies to reduce numerical error to allow appropriate comparisons of the results. It was determined that the sophisticated Reynolds stress model (RSM) provided the best results. It was later determined that the flow is an unsteady flow wherein circulating eddies grow behind the tube and ‘peel off’ alternately from the top and the bottom of the tube. Additional calculations show that the mean velocity is well predicted when the flow is modeled as an unsteady flow. The results for U are clearly superior for the unsteady computations; the unsteady computations for the turbulence stress are similar to those for the steady calculations, showing the same trends. It is clear that strategie

Richard W.Johnson; Tara Gallaway; Donna P. Guillen

2006-09-01T23:59:59.000Z

403

COMPARISON OF EXPERIMENTS TO CFD MODELS FOR MIXING USING DUAL OPPOSING JETS IN TANKS WITH AND WITHOUT INTERNAL OBSTRUCTIONS  

SciTech Connect

This paper documents testing methods, statistical data analysis, and a comparison of experimental results to CFD models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an eight foot diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors such as turbulence, pump fluctuations, and eddies required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations -- or scatter -- occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times were shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy, and determined statistical correction factors that can be applied to CFD models, and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design, and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending, using a pump with dual opposing jets which re-circulate fluids in the tank to promote blending when fluids are added to the tank. In all, eighty-five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of eighty-one tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to Computational Fluid Dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test a quarter tank of water was added to a three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids, and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids was not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but in the absence of experimental validation CFD model scan be extremely misleading as a basis for design and operation decisions.

Leishear, R.; Poirier, M.; Lee, S.; Fowley, M.

2012-06-26T23:59:59.000Z

404

Adaptive-boost molecular dynamics simulation of carbon diffusion in iron  

E-Print Network (OSTI)

We have developed an accelerated molecular dynamics (MD) method to model atomic-scale rare events. In this method, a smooth histogram of collective variables is first estimated by canonical ensemble molecular dynamics ...

Ishii, Akio

405

Influence of Electrification on Microphysical and Dynamical Processes in a Numerically Simulated Thunderstorm  

Science Conference Proceedings (OSTI)

A new three-dimensional dynamics and electrification coupled model is developed to investigate the influence of electrification on microphysical and dynamical processes in thunderstorms. This model includes a four-class ice microphysics scheme, ...

Anping Sun; Hye-Yeong Chun; Jong-Jin Baik; Muhong Yan

2002-11-01T23:59:59.000Z

406

CAPE-OPEN Integration for Advanced Process Engineering Co-Simulation  

SciTech Connect

This paper highlights the use of the CAPE-OPEN (CO) standard interfaces in the Advanced Process Engineering Co-Simulator (APECS) developed at the National Energy Technology Laboratory (NETL). The APECS system uses the CO unit operation, thermodynamic, and reaction interfaces to provide its plug-and-play co-simulation capabilities, including the integration of process simulation with computational fluid dynamics (CFD) simulation. APECS also relies heavily on the use of a CO COM/CORBA bridge for running process/CFD co-simulations on multiple operating systems. For process optimization in the face of multiple and some time conflicting objectives, APECS offers stochastic modeling and multi-objective optimization capabilities developed to comply with the CO software standard. At NETL, system analysts are applying APECS to a wide variety of advanced power generation systems, ranging from small fuel cell systems to commercial-scale power plants including the coal-fired, gasification-based FutureGen power and hydrogen production plant.

Zitney, S.E.

2006-11-01T23:59:59.000Z

407

Improving Health Care Management Through the Use of Dynamic Simulation Modeling and Health Information Systems  

Science Conference Proceedings (OSTI)

To better understand the performance of hospital operations in response to IT-enabled improvement, this paper reports the results of a system dynamics model designed to improve core medical processes. Utilizing system dynamics modeling and emerging Health ... Keywords: Health Information Systems, Heath Care, Hospital Management, Process Improvement, System Dynamics

Daniel Goldsmith; Michael Siegel

2012-01-01T23:59:59.000Z

408

Dissipative particle dynamics simulation of fluid motion through an unsaturated fracture and fracture junction  

Science Conference Proceedings (OSTI)

Multiphase fluid motion in unsaturated fractures and fracture networks involves complicated fluid dynamics, which is difficult to model using grid-based continuum methods. In this paper, the application of dissipative particle dynamics (DPD), a relatively ... Keywords: Dissipative particle dynamics (DPD), Fracture, Fracture flow, Smoothed particle hydrodynamics (SPH), Weight functions

Moubin Liu; Paul Meakin; Hai Huang

2007-03-01T23:59:59.000Z

409

Computational Fluid Dynamics of rising droplets  

SciTech Connect

The main goal of this study is to perform simulations of droplet dynamics using Truchas, a LANL-developed computational fluid dynamics (CFD) software, and compare them to a computational study of Hysing et al.[IJNMF, 2009, 60:1259]. Understanding droplet dynamics is of fundamental importance in liquid-liquid extraction, a process used in the nuclear fuel cycle to separate various components. Simulations of a single droplet rising by buoyancy are conducted in two-dimensions. Multiple parametric studies are carried out to ensure the problem set-up is optimized. An Interface Smoothing Length (ISL) study and mesh resolution study are performed to verify convergence of the calculations. ISL is a parameter for the interface curvature calculation. Further, wall effects are investigated and checked against existing correlations. The ISL study found that the optimal ISL value is 2.5{Delta}x, with {Delta}x being the mesh cell spacing. The mesh resolution study found that the optimal mesh resolution is d/h=40, for d=drop diameter and h={Delta}x. In order for wall effects on terminal velocity to be insignificant, a conservative wall width of 9d or a nonconservative wall width of 7d can be used. The percentage difference between Hysing et al.[IJNMF, 2009, 60:1259] and Truchas for the velocity profiles vary from 7.9% to 9.9%. The computed droplet velocity and interface profiles are found in agreement with the study. The CFD calculations are performed on multiple cores, using LANL's Institutional High Performance Computing.

Wagner, Matthew [Lake Superior State University; Francois, Marianne M. [Los Alamos National Laboratory

2012-09-05T23:59:59.000Z

410

CFD MODELING ANALYSIS OF MECHANICAL DRAFT COOLING TOWER  

Science Conference Proceedings (OSTI)

Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has a MDCT consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to conduct a parametric study for cooling tower performance under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model to achieve the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of the modeling calculations was performed to investigate the impact of ambient and operating conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was benchmarked against the literature data and the SRS test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be presented here.

Lee, S; Alfred Garrett, A; James02 Bollinger, J; Larry Koffman, L

2008-03-03T23:59:59.000Z

411

CFD analysis and experimental investigation associated with the design of the Los Alamos nuclear materials storage facility  

Science Conference Proceedings (OSTI)

The Nuclear Materials Storage Facility (NMSF) at the Los Alamos National Laboratory is being renovated for long-term storage of canisters designed to hold heat-generating nuclear materials, such as powders, ingots, and other components. The continual heat generation within the canisters necessitates a reliable cooling scheme of sufficient magnitude which maintains the stored material temperatures within acceptable limits. The primary goal of this study was to develop both an experimental facility and a computational fluid dynamics (CFD) model of a subsection of the NMSF which could be used to observe general performance trends of a proposed passive cooling scheme and serve as a design tool for canister holding fixtures. Comparisons of numerical temperature and velocity predictions with empirical data indicate that the CFD model provides an accurate representation of the NMSF experimental facility. Minor modifications in the model geometry and boundary conditions are needed to enhance its accuracy, however, the various fluid and thermal models correctly capture the basic physics.

Bernardin, J.D.; Hopkins, S.; Gregory, W.S.; Martin, R.A. [and others

1997-06-01T23:59:59.000Z

412

CFD Predictions of Severe Accident Steam Generator Flows in a 1/7. Scale Pressurized Water Reactor  

SciTech Connect

Computational Fluid Dynamics (CFD) is applied to steam generator inlet plenum mixing as part of a larger plan covering steam generator tube integrity. The technique is verified by comparing predicted results with severe accident natural circulation data from a 1/7. scale Westinghouse facility. This exercise demonstrates that the technique can predict the natural circulation and mixing phenomena relevant to steam generator tube integrity issues. The model includes primary side flow paths for a single hot leg and steam generator. Qualitatively, the experimentally observed flow phenomena are predicted. The paths of the natural circulation flows and the relative flow proportions are correctly predicted. Quantitatively, comparisons are made with temperatures, mass flows, and other parameters. All predictions are generally within 10% of the experimental values. Overall, there is a high degree of confidence in the CFD technique for prediction of the relevant flow phenomena associated with this type of severe accident sequence. (authors)

Boyd, Christopher; Hardesty, Kelly [U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001 (United States)

2002-07-01T23:59:59.000Z

413

System implementation issues of dynamic discrete disaster decision simulation system (D4S2): phase I  

Science Conference Proceedings (OSTI)

Simulation has many advantages in modeling complex systems to facilitate decision making. In this research, an integrated computer system will be developed which incorporates an agent-based discrete event simulator, a geographic information system, a ...

Shengnan Wu; Larry J. Shuman; Bopaya Bidanda; Matthew Kelley; Bryan Lawson; Ken Sochats; Carey D. Balaban

2007-12-01T23:59:59.000Z

414

The Interaction of Radiative and Dynamical Processes during a Simulated Sudden Stratospheric Warming  

Science Conference Proceedings (OSTI)

An analysis of a spontaneous sudden stratospheric warming that occurred during a 2-year integration of the Langley Research Center Atmospheric Simulation Model is presented. The simulated warming resembles observed “wave 1&rdquo warmings in the ...

R. B. Pierce; W. T. Blackshear; W. L. Grose; R. E. Turner; T. D. Fairlie

1993-12-01T23:59:59.000Z

415

AMG for linear systems in engine flow simulations  

Science Conference Proceedings (OSTI)

The performance of three fundamentally different AMG solvers for systems of linear equations in CFD simulations using SIMPLE and PISO algorithm is examined. The presented data is discussed with respect to computational aspects of the parallelisation. ...

Maximilian Emans

2009-09-01T23:59:59.000Z

416

COMPARISON OF EXPERIMENTAL RESULTS TO CFD MODELS FOR BLENDING IN A TANK USING DUAL OPPOSING JETS  

Science Conference Proceedings (OSTI)

Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1- 4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.

Leishear, R.

2011-08-07T23:59:59.000Z

417

PIV Uncertainty Methodologies for CFD Code Validation at the MIR Facility  

SciTech Connect

Currently, computational fluid dynamics (CFD) is widely used in the nuclear thermal hydraulics field for design and safety analyses. To validate CFD codes, high quality multi dimensional flow field data are essential. The Matched Index of Refraction (MIR) Flow Facility at Idaho National Laboratory has a unique capability to contribute to the development of validated CFD codes through the use of Particle Image Velocimetry (PIV). The significance of the MIR facility is that it permits non intrusive velocity measurement techniques, such as PIV, through complex models without requiring probes and other instrumentation that disturb the flow. At the heart of any PIV calculation is the cross-correlation, which is used to estimate the displacement of particles in some small part of the image over the time span between two images. This image displacement is indicated by the location of the largest peak. In the MIR facility, uncertainty quantification is a challenging task due to the use of optical measurement techniques. Currently, this study is developing a reliable method to analyze uncertainty and sensitivity of the measured data and develop a computer code to automatically analyze the uncertainty/sensitivity of the measured data. The main objective of this study is to develop a well established uncertainty quantification method for the MIR Flow Facility, which consists of many complicated uncertainty factors. In this study, the uncertainty sources are resolved in depth by categorizing them into uncertainties from the MIR flow loop and PIV system (including particle motion, image distortion, and data processing). Then, each uncertainty source is mathematically modeled or adequately defined. Finally, this study will provide a method and procedure to quantify the experimental uncertainty in the MIR Flow Facility with sample test results.

Piyush Sabharwall; Richard Skifton; Carl Stoots; Eung Soo Kim; Thomas Conder

2013-12-01T23:59:59.000Z

418

Simulating past and future dynamics of natural ecosystems in the United States. Global Biogeochemical Cycles 17(2)1045  

E-Print Network (OSTI)

[1] Simulations of potential vegetation distribution, natural fire frequency, carbon pools, and fluxes are presented for two DGVMs (Dynamic Global Vegetation Models) from the second phase of the Vegetation/Ecosystem Modeling and Analysis Project. Results link vegetation dynamics to biogeochemical cycling for the conterminous United States. Two climate change scenarios were used: a moderately warm scenario from the Hadley Climate Centre and a warmer scenario from the Canadian Climate Center. Both include sulfate aerosols and assume a gradual CO2 increase. Both DGVMs simulate a reduction of southwestern desert areas, a westward expansion of eastern deciduous forests, and the expansion of forests in the western part of the Pacific Northwest and in north-central California. Both DGVMs predict an increase in total biomass burnt in the next century, with a more pronounced increase under the Canadian scenario. Under the Hadley scenario, both DGVMs simulate increases in total carbon stocks. Under the Canadian scenario, both DGVMs simulate a decrease in live vegetation carbon. We identify similarities in model behavior due to the climate forcing and explain differences by the different structure of the models and their different sensitivity to

Dominique Bachelet; Ronald P. Neilson; Thomas Hickler; Raymond J. Drapek; James M. Lenihan; Martin T. Sykes; Benjamin Smith; Stephen Sitch; Kirsten Thonicke

2003-01-01T23:59:59.000Z

419

DOI: 10.1017/S1464793103006419 Printed in the United Kingdom Vegetation dynamicssimulating responses to climatic change  

E-Print Network (OSTI)

A modelling approach to simulating vegetation dynamics is described, incorporating critical processes of carbon sequestration, growth, mortality and distribution. The model has been developed to investigate the responses of vegetation to environmental change, at time scales from days to centuries and from the local to the global scale. The model is outlined and subsequent tests, against independent data sources, are relatively successful, from the small scale to the global scale. Tests against eddy covariance observations of carbon exchange by vegetation indicated significant differences between measured and simulated net ecosystem production (NEP). NEP is the net of large fluxes due to gross primary production and respiration, which are not directly measured and so there is some uncertainty in explaining differences between observations and simulations. In addition it was noted that closer agreement of fluxes was achieved for natural, or long-lived managed vegetation than for recently managed vegetation. The discrepancies appear to be most closely related to respiratory carbon losses from the soil, but this area needs further exploration. The differences do not scale up to the global scale, where simulated and measured global net biome production were similar, indicating that fluxes measured at the managed observed sites are not typical globally. The model (the Sheffield Dynamic Global Vegetation Model, SDGVM) has been applied to contemporary

F. I. Woodward; M. R. Lomas

2003-01-01T23:59:59.000Z

420

Calibration and Validation of a Spar-Type Floating Offshore Wind Turbine Model using the FAST Dynamic Simulation Tool: Preprint  

DOE Green Energy (OSTI)

In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states.

Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

2012-11-01T23:59:59.000Z

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421

Calibration and Validation of a Spar-Type Floating Offshore Wind Turbine Model using the FAST Dynamic Simulation Tool: Preprint  

SciTech Connect

In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states.

Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

2012-11-01T23:59:59.000Z

422

Numerical Simulation of Squeeze Film Dampers and Study of the Effect of Central Groove on the Dynamic Pressure Distribution  

E-Print Network (OSTI)

Squeeze film dampers are used in the high speed turbo machinery industry and aerospace industries as a means to reduce vibration amplitude, to provide damping, to improve dynamic stability of the rotor bearing system and to isolate structural components. The effects of cavitation included in previous studies were not effective. The effect of different design parameters were not studied thoroughly as experimental investigation of squeeze film dampers is very expensive. Few of them used numerical investigation but the methods they used are either time consuming or complicated. The present study investigated the feasibility of applying a steady state solver, which is computationally less expensive, for analyzing flow field inside the squeeze film dampers. The behavior of dynamic pressure profiles at different operating conditions, and the effect of a central groove on dynamic pressure profiles were also studied. Simulation results of a 3D case which is similar to the one experimentally studied by Delgado were used to establish if the moving reference frame (MRF) model in Fluent 12.1 can be used. A steady state solver in an absolute frame of reference was used to produce whirling motion of the rotor in this study. The inlet pressure of 31kpa and the whirling speed of 50 and 100Hz were used as boundary conditions. The mixture model with three percent dissolved air in lubricant is used to model multiphase flow. Singhal cavitation model is used to model cavitation. The simulations (50,000 iterations) were run until steady state solutions were reached. The results closely agreed with those obtained experimentally by San Andrés and Delgado. Numerical simulations of three-dimensional cases with an additional central groove on the squeeze film land were also performed to predict the effect of central groove on dynamic pressure profiles. Addition central groove reduces the pressures and forces generated by squeeze film damper.

Boppa, Praneetha

2011-08-01T23:59:59.000Z

423

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

Science Conference Proceedings (OSTI)

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

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

2006-02-01T23:59:59.000Z

424

STRUCTURAL VALIDATION OF SYSTEM DYNAMICS AND AGENT-BASED SIMULATION MODELS  

E-Print Network (OSTI)

, population dynamics, energy systems, and urban planning. The usefulness of these models is predicated be opened in the bank; efficiency of the oil refinery can be enhanced under the recommended actions including global warming, population dynamics, energy systems, and urban planning simply defy a face

Tesfatsion, Leigh

425

A next-generation modeling capability assesses wind turbine array fluid dynamics and aeroelastic simulations  

E-Print Network (OSTI)

A next-generation modeling capability assesses wind turbine array fluid dynamics and aeroelastic conditions with turbine models covering the range of scales important for wind plant dynamics to help address the impacts that upwind turbines have on turbines in their wake and give greater insight into overall wind

426

Modeling and simulation of new configuration of dynamic voltage restorer for power quality improvement  

Science Conference Proceedings (OSTI)

The dynamic voltage restorer (DVR) is a custom device that is used to maintain the voltage at the load terminals from various power quality problems from a disturbed incoming supply. In this paper, a novel control strategy is described for mitigation ... Keywords: custom device, dynamic voltage restorer (DVR), power quality, sags, sensitive loads, swells

Rosli Omar; Nasrudin Abdul Rahim

2011-04-01T23:59:59.000Z

427

Dynamics of a Myoglobin Mutant Enzyme: 2D IR Vibrational Echo Experiments and Simulations  

E-Print Network (OSTI)

and A3 substates. The equilibrium protein dynamics for the two distinct substates of the Mb double for both of the substates are analyzed using the center line slope (CLS) method to obtain the frequency on the electronic ground state potential energy surface. Therefore, it is useful to study protein dynamics

Fayer, Michael D.

428

Nonequilibrium molecular dynamics simulation of shear viscosity by a uniform momentum source-and-sink scheme  

Science Conference Proceedings (OSTI)

A uniform momentum source-and-sink scheme of nonequilibrium molecular dynamics (NEMD) is developed to calculate the shear viscosity of fluids in this paper. The uniform momentum source and sink are realized by momentum exchanges of individual atoms in ... Keywords: Molecular fluid, Nonequilibrium molecular dynamics, Shear viscosity, Uniform source-and-sink scheme

Bing-Yang Cao; Ruo-Yu Dong

2012-06-01T23:59:59.000Z

429

Molecular Dynamics Simulation of Solidification in Cu50Zr50 Alloy  

Science Conference Proceedings (OSTI)

Next, MD simulation of melting B2 phase surrounded by liquid was .... Thermochemical Models and Phase Equilibria of Urania Rare Earth Fluorite Phases.

430

Implied Dynamic Feedback of 3D IR Radiative Transfer on Simulated...  

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

of 3D IR Radiative Transfer on Simulated Cloud Fields D. B. Mechem and Y. L. Kogan Cooperative Institute for Mesoscale Meteorological Studies University of Oklahoma Norman,...

431

3D CFD Model of a Multi-Cell High Temperature Electrolysis Stack  

DOE Green Energy (OSTI)

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis stack performance and steam electrolysis in the Idaho National Laboratory Integrated Lab Scale (ILS) experiment. The model is made of 60 planar cells stacked on top of each other operated as Solid Oxide Electrolysis Cells (SOEC). Details of the model geometry are specific to a stack that was fabricated by Ceramatec, Inc1. and tested at the Idaho National Laboratory. Inlet and outlet plenum flow and distribution are considered. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT2. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC userdefined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation overpotential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Variations in flow distribution, and species concentration are discussed. End effects of flow and per-cell voltage are also considered.

G.L. Hawkes; J. E. O'Brien; C. M. Stoots

2007-11-01T23:59:59.000Z

432

Compilation of CFD Models of Various Solid Oxide Electrolyzers Analyzed at the Idaho National Laboratory  

SciTech Connect

Various three dimensional computational fluid dynamics (CFD) models of solid oxide electrolyzers have been created and analyzed at the Idaho National Laboratory since the inception of the Nuclear Hydrogen Initiative in 2004. Three models presented herein include: a 60 cell planar cross flow with inlet and outlet plenums, 10 cell integrated planar cross flow, and internally manifolded five cell planar cross flow. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) module adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Contour plots of local electrolyte temperature, current density, and Nernst potential indicated the effects of heat transfer, endothermic reaction, Ohmic heating, and change in local gas composition. Results are discussed for using these models in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production is reported herein. Contour plots and discussion show areas of likely cell degradation, flow distribution in inlet plenum, and flow distribution across and along the flow channels of the current collectors

Grant Hawkes; James O'Brien

2012-06-01T23:59:59.000Z

433

3-D CFD MODEL OF A MULTI-CELL HIGH TEMPERATURE ELECTROLYSIS STACK  

DOE Green Energy (OSTI)

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis stack performance and steam electrolysis in the Idaho National Laboratory (INL) Integrated Lab Scale (ILS) experiment. The model is made of 60 planar cells stacked on top of each other operated as Solid Oxide Electrolysis Cells (SOEC). Details of the model geometry are specific to a stack that was fabricated by Ceramatec, Inc. and tested at INL. Inlet and outlet plenum flow and distribution are considered. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density, and hydrogen production over a range of stack operating conditions. Variations in flow distribution and species concentration are discussed. End effects of flow and per-cell voltage are also considered.

Grant Hawkes; James O'Brien; Carl Stoots; Brian Hawkes

2009-05-01T23:59:59.000Z

434

Dynamic Simulation Studies of the Frequency Response of the Three U.S. Interconnections with Increased Wind Generation  

SciTech Connect

Utility Systems Efficiencies, Inc. was tasked by Lawrence Berkeley National Laboratory (LBNL) to conduct dynamic simulation studies of the three U.S. interconnections (Eastern, Western, and Texas). The simulations were prepared in support of LBNL's project for the Federal Energy Regulatory Commission to study frequency-response-related issues that must be addressed to operate the power system reliably with large amounts of variable renewable generation. The objective of the simulation studies of each interconnection was to assess the effects of different amounts of wind generation on frequency behavior of each interconnection following a sudden loss of generation. The scenarios created to study these effects considered an operating circumstance in which system load is at or close to its minimum. The event studied was the sudden loss of the largest amount of generation recorded within each interconnection. The simulations calculated the impact of this event on interconnection frequency for three levels of wind generation. In addition to varying the amount of wind generation, the simulations varied the amount of operating reserves between a high level representative of current operating practices and a low level representative of the minimum required by present operating rules.

Mackin, Peter; Daschmans, R.; Williams, B.; Haney, B.; Hung, R.; Ellis, J.

2010-12-20T23:59:59.000Z

435

Dynamic Simulation Studies of the Frequency Response of the Three U.S. Interconnections with Increased Wind Generation  

SciTech Connect

Utility Systems Efficiencies, Inc. was tasked by Lawrence Berkeley National Laboratory (LBNL) to conduct dynamic simulation studies of the three U.S. interconnections (Eastern, Western, and Texas). The simulations were prepared in support of LBNL's project for the Federal Energy Regulatory Commission to study frequency-response-related issues that must be addressed to operate the power system reliably with large amounts of variable renewable generation. The objective of the simulation studies of each interconnection was to assess the effects of different amounts of wind generation on frequency behavior of each interconnection following a sudden loss of generation. The scenarios created to study these effects considered an operating circumstance in which system load is at or close to its minimum. The event studied was the sudden loss of the largest amount of generation recorded within each interconnection. The simulations calculated the impact of this event on interconnection frequency for three levels of wind generation. In addition to varying the amount of wind generation, the simulations varied the amount of operating reserves between a high level representative of current operating practices and a low level representative of the minimum required by present operating rules.

Mackin, Peter; Daschmans, R.; Williams, B.; Haney, B.; Hung, R.; Ellis, J.

2010-12-20T23:59:59.000Z

436

A localised subgrid scale model for fluid dynamical simulations in astrophysics II: Application to type Ia supernovae  

E-Print Network (OSTI)

The dynamics of the explosive burning process is highly sensitive to the flame speed model in numerical simulations of type Ia supernovae. Based upon the hypothesis that the effective flame speed is determined by the unresolved turbulent velocity fluctuations, we employ a new subgrid scale model which includes a localised treatment of the energy transfer through the turbulence cascade in combination with semi-statistical closures for the dissipation and non-local transport of turbulence energy. In addition, subgrid scale buoyancy effects are included. In the limit of negligible energy transfer and transport, the dynamical model reduces to the Sharp-Wheeler relation. According to our findings, the Sharp-Wheeler relation is insuffcient to account for the complicated turbulent dynamics of flames in thermonuclear supernovae. The application of a co-moving grid technique enables us to achieve very high spatial resolution in the burning region. Turbulence is produced mostly at the flame surface and in the interior ash regions. Consequently, there is a pronounced anisotropy in the vicinity of the flame fronts. The localised subgrid scale model predicts significantly enhanced energy generation and less unburnt carbon and oxygen at low velocities compared to earlier simulations.

W. Schmidt; J. C. Niemeyer; W. Hillebrandt; F. K. Roepke

2006-01-23T23:59:59.000Z

437

Analysis of fluid flow and heat transfer in a rib grit roughened surface solar air heater using CFD  

SciTech Connect

This paper presents the study of fluid flow and heat transfer in a solar air heater by using Computational Fluid Dynamics (CFD) which reduces time and cost. Lower side of collector plate is made rough with metal ribs of circular, square and triangular cross-section, having 60 inclinations to the air flow. The grit rib elements are fixed on the surface in staggered manner to form defined grid. The system and operating parameters studied are: e/D{sub h} = 0.044, p/e = 17.5 and l/s = 1.72, for the Reynolds number range 3600-17,000. To validate CFD results, experimental investigations were carried out in the laboratory. It is found that experimental and CFD analysis results give the good agreement. The optimization of rib geometry and its angle of attack is also done. The square cross-section ribs with 58 angle of attack give maximum heat transfer. The percentage enhancement in the heat transfer for square plate over smooth surface is 30%. (author)

Karmare, S.V. [Department of Mechanical Engineering, Government College Engineering, Karad 415 124, Maharashtra (India); Shivaji University, Kolhapur, Maharashtra (India); Tikekar, A.N. [Department of Mechanical Engineering, Walchand College of Engineering, Sangli (India); Shivaji University, Kolhapur, Maharashtra (India)

2010-03-15T23:59:59.000Z

438

Dynamic simulation of a solar-driven carbon dioxide transcritical power system for small scale combined heat and power production  

SciTech Connect

Carbon dioxide is an environmental benign natural working fluid and has been proposed as a working media for a solar-driven power system. In the current work, the dynamic performance of a small scale solar-driven carbon dioxide power system is analyzed by dynamic simulation tool TRNSYS 16 and Engineering Equation Solver (EES) using co-solving technique. Both daily performance and yearly performance of the proposed system have been simulated. Different system operating parameters, which will influence the system performance, have been discussed. Under the Swedish climatic condition, the maximum daily power production is about 12 kW h and the maximum monthly power production is about 215 kW h with the proposed system working conditions. Besides the power being produced, the system can also produce about 10 times much thermal energy, which can be used for space heating, domestic hot water supply or driving absorption chillers. The simulation results show that the proposed system is a promising and environmental benign alternative for conventional low-grade heat source utilization system. (author)

Chen, Y.; Lundqvist, Per [Div. of Applied Thermodynamics and Refrigeration, Department of Energy Technology, Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Pridasawas, Wimolsiri [King Mongkut's University of Technology Thonburi, Dept. of Chemical Engineering, Bangkok (Thailand)

2010-07-15T23:59:59.000Z