Modeling-Computer Simulations At Fish Lake Valley Area (Deymonaz...
Modeling-Computer Simulations At Fish Lake Valley Area (Deymonaz, Et Al., 2008) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Modeling-Computer...
Modeling-Computer Simulations At Nw Basin & Range Region (Pritchett...
Modeling-Computer Simulations At Nw Basin & Range Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Modeling-Computer...
Modeling-Computer Simulations At Nw Basin & Range Region (Biasi...
Modeling-Computer Simulations At Nw Basin & Range Region (Biasi, Et Al., 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Modeling-Computer...
Modeling-Computer Simulations At Nevada Test And Training Range...
Modeling-Computer Simulations At Nevada Test And Training Range Area (Sabin, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity:...
Modeling-Computer Simulations At San Juan Volcanic Field Area...
Area Exploration Technique Modeling-Computer Simulations Activity Date Usefulness useful DOE-funding Unknown Notes In this study we combine thermal maturation models, based on the...
Modeling-Computer Simulations At Fenton Hill HDR Geothermal Area...
Modeling-Computer Simulations At Fenton Hill HDR Geothermal Area (Brown & DuTeaux, 1997) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity:...
Modeling-Computer Simulations At Walker-Lane Transitional Zone...
Pritchett, 2004) Exploration Activity Details Location Walker-Lane Transition Zone Geothermal Region Exploration Technique Modeling-Computer Simulations Activity Date Usefulness...
Modeling-Computer Simulations At Central Nevada Seismic Zone...
Modeling-Computer Simulations At Central Nevada Seismic Zone Region (Pritchett, 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity:...
Modeling-Computer Simulations At Central Nevada Seismic Zone...
Modeling-Computer Simulations At Central Nevada Seismic Zone Region (Biasi, Et Al., 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity:...
Modeling-Computer Simulations At Stillwater Area (Wisian & Blackwell...
Exploration Activity Details Location Stillwater Area Exploration Technique Modeling-Computer Simulations Activity Date Usefulness not indicated DOE-funding Unknown References...
Modeling-Computer Simulations At Desert Peak Area (Wisian & Blackwell...
Exploration Activity Details Location Desert Peak Area Exploration Technique Modeling-Computer Simulations Activity Date Usefulness not indicated DOE-funding Unknown References...
Modeling-Computer Simulations At Dixie Valley Geothermal Area...
W. Wisian, David D. Blackwell (2004) Numerical Modeling Of Basin And Range Geothermal Systems Additional References Retrieved from "http:en.openei.orgwindex.php?titleModel...
Modeling-Computer Simulations At Kilauea East Rift Geothermal...
East Rift Zone Notes Three models were made from data collected in the exploratory well HGP-A. The models simulated constant heat sources from a vertical dike, a magma chamber,...
Simulating Reionization in Numerical Cosmology
Aaron Sokasian; Tom Abel; Lars E. Hernquist
2001-05-10
The incorporation of radiative transfer effects into cosmological hydrodynamical simulations is essential for understanding how the intergalactic medium (IGM) makes the transition from a neutral medium to one that is almost fully ionized. Here, we present an approximate numerical method designed to study in a statistical sense how a cosmological density field is ionized by a set of discrete point sources. A diffuse background radiation field is also computed self-consistently in our procedure. The method requires relatively few time steps and can be employed with simulations having high resolution. We describe the details of the algorithm and provide a description of how the method can be applied to the output from a pre-existing cosmological simulation to study the systematic reionization of a particular ionic species. As a first application, we compute the reionization of He II by quasars in the redshift range 3 to 6.
Numerical wind speed simulation model
Ramsdell, J.V.; Athey, G.F.; Ballinger, M.Y.
1981-09-01
A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.
Numerical Simulation on Laser Fusion in China
Zhu Shaoping; Pei Wenbing; Xu Yan; Gu Peijun; Lan Ke; Ye Wenhua; Wu Junfeng; Li Jinghong; Gao Yaoming; Zheng Chunyang; Li Shuanggui; Mo Zeyao; Yan Jun [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Zhang Weiyan [National High-Tech Inertial Confinement Fusion Committee of China, Beijing 100088 (China)
2009-05-02
Numerical simulation is a powerful tool to get insight into the physics of laser fusion. Much effort has been devoted to develop the numerical simulation code series named LARED in China. The code series LARED are composed of six parts and enable us to have the simulation capability for the key processes in laser fusion. In recent years, a number of numerical simulations using LARED have been carried out and the simulation is checked by experiments done at the laser facility SG-II and SG-III prototype. In the present talk, some details of LARED code series will be introduced, and some simulation results, especially recent work on the opacities, will be shown.
NUMERICAL SIMULATIONS OF CHROMOSPHERIC MICROFLARES
Jiang, R. L.; Fang, C.; Chen, P. F., E-mail: fangc@nju.edu.c [Department of Astronomy, Nanjing University, Nanjing 210093 (China)
2010-02-20
With gravity, ionization, and radiation being considered, we perform 2.5 dimensional (2.5D) compressible resistive magnetohydrodynamic (MHD) simulations of chromospheric magnetic reconnection using the CIP-MOCCT scheme. The temperature distribution of the quiet-Sun atmospheric model VALC and the helium abundance (10%) are adopted. Our 2.5D MHD simulation reproduces qualitatively the temperature enhancement observed in chromospheric microflares. The temperature enhancement DELTAT is demonstrated to be sensitive to the background magnetic field, whereas the total evolution time DELTAt is sensitive to the magnitude of the anomalous resistivity. Moreover, we found a scaling law, which is described as DELTAT/DELTAt {approx} n{sub H} {sup -1.5} B {sup 2.1}eta{sub 0} {sup 0.88}. Our results also indicate that the velocity of the upward jet is much greater than that of the downward jet, and the X-point may move up or down.
Numerical simulations of quasar absorbers
Tom Theuns
2005-07-25
The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to constrain the star formation history and the feedback processes acting in large and small galaxies. Simulations have been instrumental in investigating to what extent these parameters can be unambiguously constrained with current and future data. This paper is meant as an introduction to this subject, and reviews techniques and methods for simulating the intergalactic medium.
Numerical Simulations of Bouncing Jets
Bonito, Andrea; Lee, Sanghyun
2015-01-01
Bouncing jets are fascinating phenomenons occurring under certain conditions when a jet impinges on a free surface. This effect is observed when the fluid is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs also for non-Newtonian fluids when the jets falls in a vessel at rest containing the same fluid. We investigate numerically the impact of the experimental setting and the rheological properties of the fluid on the onset of the bouncing phenomenon. Our investigations show that the occurrence of a thin lubricating layer of air separating the jet and the rest of the liquid is a key factor for the bouncing of the jet to happen. The numerical technique that is used consists of a projection method for the Navier-Stokes system coupled with a level set formulation for the representation of the interface. The space approximation is done with adaptive finite elements. Adaptive refinement is shown to be very important to capture the thin layer of air that is responsible for the bouncing.
Development of Numerical Simulation Capabilities for In Situ...
Office of Scientific and Technical Information (OSTI)
Development of Numerical Simulation Capabilities for In Situ Heating of Oil Shale Citation Details In-Document Search Title: Development of Numerical Simulation Capabilities for In...
Numerical simulations for low energy nuclear reactions including...
Office of Scientific and Technical Information (OSTI)
Numerical simulations for low energy nuclear reactions including direct channels to validate statistical models Citation Details In-Document Search Title: Numerical simulations for...
Numerical simulations of strong incompressible magnetohydrodynamic turbulence
Mason, J.; Cattaneo, F.; Perez, J. C.; Boldyrev, S.
2012-05-15
Magnetised plasma turbulence pervades the universe and is likely to play an important role in a variety of astrophysical settings. Magnetohydrodynamics (MHD) provides the simplest theoretical framework in which phenomenological models for the turbulent dynamics can be built. Numerical simulations of MHD turbulence are widely used to guide and test the theoretical predictions; however, simulating MHD turbulence and accurately measuring its scaling properties is far from straightforward. Computational power limits the calculations to moderate Reynolds numbers and often simplifying assumptions are made in order that a wider range of scales can be accessed. After describing the theoretical predictions and the numerical approaches that are often employed in studying strong incompressible MHD turbulence, we present the findings of a series of high-resolution direct numerical simulations. We discuss the effects that insufficiencies in the computational approach can have on the solution and its physical interpretation.
Threedimensional numerical simulation for various geometries
Herbin, Raphaèle
modelling and numerical simulation of natural gasfed solid oxide cells (Solid Oxide Fuel Cell, SOFC) at a stationary regime. The principle of a Solid Oxide Fuel Cell (SOFC) is based on the conversion of the chemical is taken into account in the present model. The SOFC systems seem to be of great interest for use
Numerical simulation of an electroweak oscillon
Graham, N. [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States)
2007-10-15
Numerical simulations of the bosonic sector of the SU(2)xU(1) electroweak standard model in 3+1 dimensions have demonstrated the existence of an oscillon--an extremely long-lived, localized, oscillatory solution to the equations of motion--when the Higgs mass is equal to twice the W{sup {+-}} boson mass. It contains total energy roughly 30 TeV localized in a region of radius 0.05 fm. A detailed description of these numerical results is presented.
Numerical simulations for width fluctuations in compound elastic...
Office of Scientific and Technical Information (OSTI)
simulations for width fluctuations in compound elastic and inelastic scattering at low energies Citation Details In-Document Search Title: Numerical simulations for width...
Numerical Simulation of Laminar Reacting Flows with Complex Chemistry
Bell, John B.
Numerical Simulation of Laminar Reacting Flows with Complex Chemistry M S Day and J B Bell Lawrence: 47.40.Fw, 82.40.Py Submitted to: Combust. Theory Modelling #12;Numerical Simulation of Laminar
Numerical Simulations Unravel the Cosmic Web
C. -A. Faucher-Giguere; A. Lidz; L. Hernquist
2008-03-03
The universe is permeated by a network of filaments, sheets, and knots collectively forming a "cosmic web.'' The discovery of the cosmic web, especially through its signature of absorption of light from distant sources by neutral hydrogen in the intergalactic medium, exemplifies the interplay between theory and experiment that drives science, and is one of the great examples in which numerical simulations have played a key and decisive role. We recount the milestones in our understanding of cosmic structure, summarize its impact on astronomy, cosmology, and physics, and look ahead by outlining the challenges faced as we prepare to probe the cosmic web at new wavelengths.
Direct numerical simulation of turbulent reacting flows
Chen, J.H. [Sandia National Laboratories, Livermore, CA (United States)
1993-12-01
The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.
Collisionless microinstabilities in stellarators. II. Numerical simulations
Proll, J. H. E.; Xanthopoulos, P.; Helander, P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)
2013-12-15
Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.
Direct numerical simulations of aeolian sand ripples
Orencio Duran; Philippe Claudin; Bruno Andreotti
2014-11-07
Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns out to be driven by resonant grain trajectories, whose length is close to a ripple wavelength and whose splash leads to a mass displacement towards the ripple crests. The pattern selection results from a compromise between this destabilizing mechanism and a diffusive downslope transport which stabilizes small wavelengths. The initial wavelength is set by the ratio of the sediment flux and the erosion/deposition rate, a ratio which increases linearly with the wind velocity. We show that this scaling law, in agreement with experiments, originates from an interfacial layer separating the saltation zone from the static sand bed, where momentum transfers are dominated by mid-air collisions. Finally, we provide quantitative support for the use the propagation of these ripples as a proxy for remote measurements of sediment transport.
Development of Numerical Simulation Capabilities for In Situ...
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Numerical Simulation Capabilities for In Situ Heating of Oil Shale Hoda, Nazish ExxonMobil Upstream Research Company, Houston, TX, USA; Fang, Chen ExxonMobil Upstream Research...
Numerical simulation of the environmental impact of hydraulic...
Office of Scientific and Technical Information (OSTI)
Numerical simulation of the environmental impact of hydraulic fracturing of tightshale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs,...
Energy stable schemes and numerical simulations of two phase ...
Title: Energy stable schemes and numerical simulations of two phase complex fluids by the phase-field method Abstact: We present an energetic variational ...
Direct Numerical Simulations and Robust Predictions of Cloud...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
cloud. Credit: Computational Science and Engineering Laboratory, ETH Zurich, Switzerland Direct Numerical Simulations and Robust Predictions of Cloud Cavitation Collapse PI Name:...
Numerical Simulation of Laminar Reacting Flows with Complex Chemistry
Bell, John B.
Numerical Simulation of Laminar Reacting Flows with Complex Chemistry M S Day and J B Bell Lawrence Simulation of Laminar Reacting Flows 2 1. Introduction Detailed modelling of time-dependent reacting ows
A numerical model simulation of longshore transport for Galveston Island
Gilbreath, Stephen Alexander
1995-01-01
The shoreline changes, deposition patterns, and longshore transport rates were calculated for the coast of Galveston Island using a numerical model simulation. The model only simulated changes due to waves creating longshore currents. East Beach...
Direct Numerical Simulation of the Flow in a Pebble Bed
Ward, Paul
2014-06-24
at Argonne National Laboratory, to conduct both large eddy simulation (LES) and direct numerical simulation (DNS) of fluid flow through a single face-centered cubic sphere lattice with periodic boundary conditions. Multiple LES were conducted with varying...
Numerical Simulation of Free Standing Hybrid Risers
Hou, Tiancong
2014-08-13
and offloading (FPSO). The numerical scheme is mainly based on an existing in-house numerical code, known as COUPLE. In using COUPLE, URA is modeled as a rigid body. The URA connects a vertical steel riser and a flexible jumper, both of which are modeled by beam...
Numerical simulations of the intergalactic medium
Tom Theuns
2002-09-05
The intergalactic medium at redshifts 2--6 can be studied observationally through the absorption features it produces in the spectra of background quasars. Most of the UV-absorption lines arise in mildly overdense regions, which can be simulated reliably with current hydrodynamical simulations. Comparison of observed and simulated spectra allows one to put contraints on the model's parameters.
Numerical Simulations for Jet-Proton Interaction
McDonald, Kirk
inside the jet. Setup of the Simulation of the Circular Jet downstream upstream #12;3 Sergei's result at the Initial Time Energy deposition at x=0 plane, the pressure unit is bar upstream downstream #12;4 Results of the Simulation of the Elliptic Jet downstream upstream #12;7 Jet surface at 0 and 140 microsecond Results from
Numerical Simulations of MHD Turbulence in Accretion Disks
Steven A. Balbus; John F. Hawley
2002-03-20
We review numerical simulations of MHD turbulence. The last decade has witnessed fundamental advances both in the technical capabilities of direct numerical simulation, and in our understanding of key physical processes. Magnetic fields tap directly into the free energy sources in a sufficiently ionized gas. The result is that adverse angular velocity and adverse temperature gradients, not the classical angular momentum and entropy gradients, destabilize laminar and stratified flow. This has profound consequences for astrophysical accretion flows, and has opened the door to a new era of numerical simulation experiments.}
Numerical techniques of rigid body simulation
Eberle, David Michael
2001-01-01
. One of the goals of this thesis is overcoming this restriction. Collision detection is only one of the many hurdles which arise in simulating collisions between rigid bodies. To calculate the appropriate response of colliding bodies, the point...
Numerical simulation of flow separation control by oscillatory fluid injection
Resendiz Rosas, Celerino
2005-08-29
In this work, numerical simulations of flow separation control are performed. The sep-aration control technique studied is called 'synthetic jet actuation'. The developed code employs a cell centered finite volume scheme which handles viscous...
Numerical Simulation Study on Transpired Solar Air Collector
Wang, C.; Guan, Z.; Zhao, X.; Wang, D.
2006-01-01
The unglazed transpired solar air collector is now a well-recognized solar air heater for heating outside air directly. In this article, researchers introduced numerical simulation tools into the solar air collector research area, analyzed...
Validation of Eddy-renewal model by numerical simulation
Garbe, Christoph S.
Validation of Eddy-renewal model by numerical simulation Li-Ping Hung1,2 , Christoph S. Garbe1, E-mail: wttsai@ncu.edu.tw Abstract. The eddy-renewal model proposes that the dominant vortical flows as the diffusivity effect in the thin diffusive sublayer beneath surface. Key Words: eddy-renewal model, numerical
NUMERICAL SIMULATIONS OF TRANSVERSE COMPRESSION AND DENSIFICATION IN WOOD
Nairn, John A.
NUMERICAL SIMULATIONS OF TRANSVERSE COMPRESSION AND DENSIFICATION IN WOOD John A. Nairn1 Professor- terials is a useful tool for stress analysis and for failure modeling. Although FEA of wood as an anisotropic continuum is used, numerical modeling of realistic wood structures, including details of wood
Astrophysical jets: Observations, numerical simulations, and laboratory experiments
Bellan, Paul M.
Astrophysical jets: Observations, numerical simulations, and laboratory experiments P. M. Bellan,1; published online 22 April 2009 This paper provides summaries of ten talks on astrophysical jets given of observation, numerical modeling, and laboratory experiment. One essential feature of jets, namely
Numerical and laboratory simulations of auroral acceleration
Gunell, H.; De Keyser, J.; Mann, I.
2013-10-15
The existence of parallel electric fields is an essential ingredient of auroral physics, leading to the acceleration of particles that give rise to the auroral displays. An auroral flux tube is modelled using electrostatic Vlasov simulations, and the results are compared to simulations of a proposed laboratory device that is meant for studies of the plasma physical processes that occur on auroral field lines. The hot magnetospheric plasma is represented by a gas discharge plasma source in the laboratory device, and the cold plasma mimicking the ionospheric plasma is generated by a Q-machine source. In both systems, double layers form with plasma density gradients concentrated on their high potential sides. The systems differ regarding the properties of ion acoustic waves that are heavily damped in the magnetosphere, where the ion population is hot, but weakly damped in the laboratory, where the discharge ions are cold. Ion waves are excited by the ion beam that is created by acceleration in the double layer in both systems. The efficiency of this beam-plasma interaction depends on the acceleration voltage. For voltages where the interaction is less efficient, the laboratory experiment is more space-like.
Numerical simulation of water flow around a rigid fishing net
Roger Lewandowski; Géraldine Pichot
2006-12-20
This paper is devoted to the simulation of the flow around and inside a rigid axisymmetric net. We describe first how experimental data have been obtained. We show in detail the modelization. The model is based on a Reynolds Averaged Navier-Stokes turbulence model penalized by a term based on the Brinkman law. At the out-boundary of the computational box, we have used a "ghost" boundary condition. We show that the corresponding variational problem has a solution. Then the numerical scheme is given and the paper finishes with numerical simulations compared with the experimental data.
NUMERICAL SIMULATION OF AIR POLLUTION DYNAMICS DUE TO
Olszewski Jr., Edward A.
spots. Global weather patterns effected. CO2 and other pollutant emissions contributing to globalNUMERICAL SIMULATION OF AIR POLLUTION DYNAMICS DUE TO POINT SOURCE EMISSIONS FROM AN INDUSTRIAL, and ultimately effects the global climate balance. · About 60% of emissions from point sources · Major pollutants
Flow Forcing Techniques for Numerical Simulation of Combustion Instabilities
Nicoud, Franck
Flow Forcing Techniques for Numerical Simulation of Combustion Instabilities A. KAUFMANN* and F of combustion instabilities in gas turbine combustors require the knowledge of flame transfer functions. Those flame) and for one case where a CFD code is necessary (a laminar Bunsen-type flame). © 2002
Numerical Simulation in Applied Geophysics. From the Mesoscale to the
Santos, Juan
Seismic wave propagation is a common technique used in hydrocarbon exploration geophysics, mining's crust and induce attenuation, dispersion and anisotropy of the seismic waves observed at the macroscale process. Numerical Simulation in Applied Geophysics. From the Mesoscale to the Macroscale p. #12
Stress and diffusion induced interface motion: Modelling and numerical simulations
Styles, Vanessa
Stress and diffusion induced interface motion: Modelling and numerical simulations Harald Garcke of Mathematics, University of Sussex, Brighton, BN1 9QH, U.K. Abstract We propose a phase field model for stress stress effects. In this paper we will demonstrate that the model can also be used to describe other
Direct Numerical Simulations and Modeling of Jets in Crossflow
Mahesh, Krishnan
Direct Numerical Simulations and Modeling of Jets in Crossflow A THESIS SUBMITTED TO THE FACULTY. i #12;To my parents and my grandparents, and to Ramnath ii #12;Abstract Jets in crossflow are used to study the different aspects of round jets in a crossflow. The first problem studies
Control of Jets in Crossflow using Direct Numerical Simulations
Mahesh, Krishnan
Control of Jets in Crossflow using Direct Numerical Simulations A THESIS SUBMITTED TO THE FACULTY in crossflow by axial pulsing. Our main idea is that pulsing generates vortex rings; the effect of pulsing on jets in crossflow can therefore be explained by studying the behavior of vortex rings in crossflow
Numerical simulation of ceramic breeder pebble bed thermal creep behavior
Abdou, Mohamed
Numerical simulation of ceramic breeder pebble bed thermal creep behavior Alice Ying *, Hulin Huang Abstract The evolution of ceramic breeder pebble bed thermal creep deformation subjected to an external of ceramic breeder pebble beds under thermomechanical loads is necessary to ensure that the integrity of beds
Numerical Simulations Concerning the Propagation of Protostellar Jets
Numerical Simulations Concerning the Propagation of Protostellar Jets A thesis submitted, Miruna, Natalie, Olena, Pat, Prakash, Ram, Rhona, Shane, Simon, Sri, Timur, Toby, Tolis, Tony, Tom;#12;Summary A protostellar jet is a highly supersonic stream of material which heralds the birth of a star
Numerical Simulation of the December 26, 2004: Indian Ocean Tsunami
Kirby, James T.
Numerical Simulation of the December 26, 2004: Indian Ocean Tsunami J. Asavanant1, M. Ioualalen2, N. Kaewbanjak1, S. Grilli3, P. Watts4, and J. Kirby5 Abstract: The December 26, 2004 tsunami is one of the most devastating tsunami in recorded history. It was generated in the Indian Ocean off the western coast
NUMERICAL SIMULATION OF NATURAL GAS-SWIRL BURNER
Ala Qubbaj
2005-03-01
A numerical simulation of a turbulent natural gas jet diffusion flame at a Reynolds number of 9000 in a swirling air stream is presented. The numerical computations were carried out using the commercially available software package CFDRC. The instantaneous chemistry model was used as the reaction model. The thermal, composition, flow (velocity), as well as stream function fields for both the baseline and air-swirling flames were numerically simulated in the near-burner region, where most of the mixing and reactions occur. The results were useful to interpret the effects of swirl in enhancing the mixing rates in the combustion zone as well as in stabilizing the flame. The results showed the generation of two recirculating regimes induced by the swirling air stream, which account for such effects. The present investigation will be used as a benchmark study of swirl flow combustion analysis as a step in developing an enhanced swirl-cascade burner technology.
Numerical Code for LHCD Simulations with Self-consistent Treatment of Alpha Particles in Tokamak Geometry
Carmignani, B
2005-01-01
Numerical simulations of welds of thick steel pieces of interest for the thermonuclear fusion ITER machine
Design and numerical simulation of thermionic electron gun
Hosseinzadeh, M
2015-01-01
This paper reports the simulation of an electron gun. The effects of some parameters on the beam quality were studied and optimal choices were identified. It gives numerical beam qualities in common electrostatic triode gun, and the dependences on design parameters such as electrode geometries and bias voltages to these electrodes are shown. An electron beam of diameter 5 mm with energy of five kilo electron volt was assumed for simulation process. Some design parameters were identified as variable parameters in the presence of space charge. These parameters are the inclination angle of emission electrode, the applied voltage to focusing electrode, the gap width between the emission electrode and the focusing electrode and the diameter of the focusing electrode. The triode extraction system is designed and optimized by using CST software (for Particle Beam Simulations). The physical design of the extraction system is given in this paper. From the simulation results, it is concluded that the inclination angle ...
A fast direct numerical simulation method for characterising hydraulic roughness
Chung, Daniel; MacDonald, Michael; Hutchins, Nicholas; Ooi, Andrew
2015-01-01
We describe a fast direct numerical simulation (DNS) method that promises to directly characterise the hydraulic roughness of any given rough surface, from the hydraulically smooth to the fully rough regime. The method circumvents the unfavourable computational cost associated with simulating high-Reynolds-number flows by employing minimal-span channels (Jimenez & Moin 1991). Proof-of-concept simulations demonstrate that flows in minimal-span channels are sufficient for capturing the downward velocity shift, that is, the Hama roughness function, predicted by flows in full-span channels. We consider two sets of simulations, first with modelled roughness imposed by body forces, and second with explicit roughness described by roughness-conforming grids. Owing to the minimal cost, we are able to conduct DNSs with increasing roughness Reynolds numbers while maintaining a fixed blockage ratio, as is typical in full-scale applications. The present method promises a practical, fast and accurate tool for character...
Numerical simulation model for vertical flow in geothermal wells
Tachimori, M.
1982-01-01
A numerical simulation model for vertical flow in geothermal wells is presented. The model consists of equations for the conservation of mass, momentum, and energy, for thermodynamic state of water, for friction losses, for slip velocity relations, and of the criteria for various flow regimes. A new set of correlations and criteria is presented for two-phase flow to improve the accuracy of predictions; bubbly flow - Griffith and Wallis correlation, slug flow - Nicklin et al. one, annular-mist flow - Inoue and Aoki and modified by the author. The simulation method was verified by data from actual wells.
Numerical simulations of the decay of primordial magnetic turbulence
Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C (Canada); Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Brandenburg, Axel [Nordita, AlbaNova University Center, Roslagstullsbacken 23, 10691 Stockholm (Sweden); Department of Astronomy, Stockholm University, SE 10691 Stockholm (Sweden); Tevzadze, Alexander G. [Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Faculty of Exact and Natural Sciences, Tbilisi State University, 1 Chavchavadze Avenue Tbilisi, GE-0128 (Georgia); Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)
2010-06-15
We perform direct numerical simulations of forced and freely decaying 3D magnetohydrodynamic turbulence in order to model magnetic field evolution during cosmological phase transitions in the early Universe. Our approach assumes the existence of a magnetic field generated either by a process during inflation or shortly thereafter, or by bubble collisions during a phase transition. We show that the final configuration of the magnetic field depends on the initial conditions, while the velocity field is nearly independent of initial conditions.
Transient productivity index for numerical well test simulations
Blanc, G.; Ding, D.Y.; Ene, A.
1997-08-01
The most difficult aspect of numerical simulation of well tests is the treatment of the Bottom Hole Flowing (BHF) Pressure. In full field simulations, this pressure is derived from the Well-block Pressure (WBP) using a numerical productivity index which accounts for the grid size and permeability, and for the well completion. This productivity index is calculated assuming a pseudo-steady state flow regime in the vicinity of the well and is therefore constant during the well production period. Such a pseudo-steady state assumption is no longer valid for the early time of a well test simulation as long as the pressure perturbation has not reached several grid-blocks around the well. This paper offers two different solutions to this problem: (1) The first one is based on the derivation of a Numerical Transient Productivity Index (NTPI) to be applied to Cartesian grids; (2) The second one is based on the use of a Corrected Transmissibility and Accumulation Term (CTAT) in the flow equation. The representation of the pressure behavior given by both solutions is far more accurate than the conventional one as shown by several validation examples which are presented in the following pages.
Numerical simulation of multi-layered textile composite reinforcement forming
Wang, P.; Hamila, N.; Boisse, P.
2011-05-04
One important perspective in aeronautics is to produce large, thick or/and complex structural composite parts. The forming stage presents an important role during the whole manufacturing process, especially for LCM processes (Liquid Composites Moulding) or CFRTP (Continuous Fibre Reinforcements and Thermoplastic resin). Numerical simulations corresponding to multi-layered composite forming allow the prediction for a successful process to produce the thick parts, and importantly, the positions of the fibres after forming to be known. This paper details a set of simulation examples carried out by using a semi-discrete shell finite element made up of unit woven cells. The internal virtual work is applied on all woven cells of the element taking into account tensions, in-plane shear and bending effects. As one key problem, the contact behaviours of tool/ply and ply/ply are described in the numerical model. The simulation results not only improve our understanding of the multi-layered composite forming process but also point out the importance of the fibre orientation and inter-ply friction during formability.
Diffusive mesh relaxation in ALE finite element numerical simulations
Dube, E.I.
1996-06-01
The theory for a diffusive mesh relaxation algorithm is developed for use in three-dimensional Arbitary Lagrange/Eulerian (ALE) finite element simulation techniques. This mesh relaxer is derived by a variational principle for an unstructured 3D grid using finite elements, and incorporates hourglass controls in the numerical implementation. The diffusive coefficients are based on the geometric properties of the existing mesh, and are chosen so as to allow for a smooth grid that retains the general shape of the original mesh. The diffusive mesh relaxation algorithm is then applied to an ALE code system, and results from several test cases are discussed.
Numerical simulation of carbon arc discharge for nanoparticle synthesis
Kundrapu, M.; Keidar, M.
2012-07-15
Arc discharge with catalyst-filled carbon anode in helium background was used for the synthesis of carbon nanoparticles. In this paper, we present the results of numerical simulation of carbon arc discharges with arc current varying from 10 A to 100 A in a background gas pressure of 68 kPa. Anode sublimation rate and current voltage characteristics are compared with experiments. Distribution of temperature and species density, which is important for the estimation of the growth of nanoparticles, is obtained. The probable location of nanoparticle growth region is identified based on the temperature range for the formation of catalyst clusters.
PHYSICAL AND NUMERICAL SIMULATIONS OF SUBSIDENCE ABOVE HIGH EXTRACTION COAL MINES
Sutherland, Herbert; Heckes, Albert; Taylor, Lee
1984-01-01
and the formation of a subsidence trough. The data fromNUMERICAL SIMULATIONS OF SUBSIDENCE ABOVE HIGH EXTRACTION
A MultiLevel Preconditioner with Applications to the Numerical Simulation of Coating Problems
Zhang, Jun
A MultiLevel Preconditioner with Applications to the Numerical Simulation of Coating Problems of unstructured sparse linear systems arising from the numerical simulation of coating problems. The coef ficient unstructured sparse linear systems from the numerical simulation of coating problems. Coating is a delicate
Numerical Relativity in Spherical Polar Coordinates: Off-center Simulations
Thomas W. Baumgarte; Pedro J. Montero; Ewald Müller
2015-06-03
We have recently presented a new approach for numerical relativity simulations in spherical polar coordinates, both for vacuum and for relativistic hydrodynamics. Our approach is based on a reference-metric formulation of the BSSN equations, a factoring of all tensor components, as well as a partially implicit Runge-Kutta method, and does not rely on a regularization of the equations, nor does it make any assumptions about the symmetry across the origin. In order to demonstrate this feature we present here several off-centered simulations, including simulations of single black holes and neutron stars whose center is placed away from the origin of the coordinate system, as well as the asymmetric head-on collision of two black holes. We also revisit our implementation of relativistic hydrodynamics and demonstrate that a reference-metric formulation of hydrodynamics together with a factoring of all tensor components avoids problems related to the coordinate singularities at the origin and on the axes. As a particularly demanding test we present results for a shock wave propagating through the origin of the spherical polar coordinate system.
MHD Remote Numerical Simulations: Evolution of Coronal Mass Ejections
L. Hernandez-Cervantes; A. Santillan; A. R. Gonzalez-Ponce
2008-12-22
Coronal mass ejections (CMEs) are solar eruptions into interplanetary space of as much as a few billion tons of plasma, with embedded magnetic fields from the Sun's corona. These perturbations play a very important role in solar--terrestrial relations, in particular in the spaceweather. In this work we present some preliminary results of the software development at the Universidad Nacional Autonoma de Mexico to perform Remote MHD Numerical Simulations. This is done to study the evolution of the CMEs in the interplanetary medium through a Web-based interface and the results are store into a database. The new astrophysical computational tool is called the Mexican Virtual Solar Observatory (MVSO) and is aimed to create theoretical models that may be helpful in the interpretation of observational solar data.
Electromagnetic Pulse Propagation over Nonuniform Earth Surface: Numerical Simulation
Alexei V. Popov; Vladimir V. Kopeikin
2007-04-14
We simulate EM pulse propagation along the nonuniform earth surface using so called time-domain parabolic equation. To solve it by finite differences, we introduce a time-domain analog of the impedance boundary condition and a nonlocal BC of transparency reducing open computational domain to a strip of finite width. Numerical examples demonstrate influence of soil conductivity on the wide-band pulse waveform. For a high-frequency modulated EM pulse, we develop an asymptotic approach based on the ray structure of the monochromatic wave field at carrier frequency. This radically diminishes the computation costs and allows for pulsed wave field calculation in vast domains measured by tens of thousands wavelengths.
Numerical simulation of linear fiction welding (LFW) processes
Fratini, L.; La Spisa, D. [University of Palermo-Dept. of Industrial engineering (Italy)
2011-05-04
Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining ''unweldable'' materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries.LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. This paper is a comparative test between the numerical model in two dimensions, i.e. in plane strain conditions, and in three dimensions of a LFW process of AISI1045 steel specimens. It must be observed that the 3D model assures a faithful simulation of the actual threedimensional material flow, even if the two-dimensional simulation computational times are very short, a few hours instead of several ones as the 3D model. The obtained results were compared with experimental values found out in the scientific literature.
A Flux-Limited Numerical Method for the MHD Equations to Simulate Propulsive Plasma Flows
Choueiri, Edgar
to be effective tools in plasma propulsion research, a higher order accu- rate solver that captures MHD shocks approach, numerical simulations are valuable tools in plasma thruster research. More- over, simulations can Simula- tions The importance of numerical simulation in advancing plasma thruster research was realized
Energy and enstrophy transfer in numerical simulations of two-dimensional' turbulence
Vallis, Geoff
Energy and enstrophy transfer in numerical simulations of two-dimensional' turbulence Mathew E a significant fraction of the flow field,w and energy spectra from these simulations have slopes significantly October 1992; accepted 25 March 1993) Numerical simulations of statistically steady two-dimensional (2-D
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolarNewsusceptometer under pressureNavyNumerical simulations of current
Advanced Numerical Methods and Software Approaches for Semiconductor Device Simulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Carey, Graham F.; Pardhanani, A. L.; Bova, S. W.
2000-01-01
In this article we concisely present several modern strategies that are applicable to driftdominated carrier transport in higher-order deterministic models such as the driftdiffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of “upwind” and artificial dissipation schemes, generalization of the traditional Scharfetter – Gummel approach, Petrov – Galerkin and streamline-upwind Petrov Galerkin (SUPG), “entropy” variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of themore »methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. We have included numerical examples from our recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and we emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, we briefly consider some aspects of software frameworks. These include dial-an-operator approaches such as that used in the industrial simulator PROPHET, and object-oriented software support such as those in the SANDIA National Laboratory framework SIERRA.« less
Numerical simulations for nodal domains and spectral minimal partitions
Vial, Grégory
unpublished results of [HHO2] with efficient numerical computations. This is the main goal of this paper
Taylor, John R.
UNIVERSITY OF CALIFORNIA, SAN DIEGO Numerical Simulations of the Stratified Oceanic Bottom Boundary of Philosophy in Mechanical Engineering by John R. Taylor Committee in charge: Sutanu Sarkar, Chair Thomas Simulation of Stably Stratified Open Channel Flow . . . . . 6 1. Introduction
Analysis of Cold Air Distribution System in an Office Building by the Numerical Simulation Method
Jian, Y.; Li, D.; Xu, H.; Ma, X.
2006-01-01
Numerical simulation is carried out in this paper to calculate indoor air patterns, which include angles of inlet direction and induced ratios in a typical official room. According to the simulation results, the indoor air distribution and indoor...
Numerical simulation of three-dimensional electrical flow through geomaterials
Akhtar, Anwar Saeed
1998-01-01
95 99 V ELECTRICAL FLOW AROUND AN ELECTRICAL CONE PENETROMETER 104 5. 1 INTRODUCTION 5. 2 ANALYTICAL SOLUTION FOR ELECTRICAL FLOW AROUND AN ELECTRICAL CONE PENETROMETER 5. 3 NUMERICAL INVESTIGATION 5. 4 COMPARISON OF ANALYTICAL AND NUMERICAL... RESULTS 5. 5 CONCLUSION AND APPLICATION 5. 5. 1 Utilization of Numerical Results 104 106 110 113 115 116 VI EXPERIMENTAL EQUIPMENT DESIGN 121 6. 1 INTRODUCTION 6. 2 ELECTRICAL POWER SOURCE 6. 3 ELECTRICAL RESISTIVITY CONE PENETROMETER 6. 4...
Numerical simulation of flow and mixing behavior of solids on a moving grate combustion system
Columbia University
Numerical simulation of flow and mixing behavior of solids on a moving grate combustion system by #12;ii Numerical simulation of flow and mixing behavior of solids on a moving grate combustion system, and to a large extent influences the combustion process. Municipal solid waste (MSW) is not a uniform fuel
OBJECT ORIENTED PROGRAMMING TECHNIQUES AND FAC METHOD IN NUMERICAL RESERVOIR SIMULATION \\Lambda
the reservoir. Combining the need for an accurate approximation of these moving features with the needOBJECT ORIENTED PROGRAMMING TECHNIQUES AND FAC METHOD IN NUMERICAL RESERVOIR SIMULATION \\Lambda in numerical simulation of flow through hydrocarbon reservoirs within limitations in computing time and memory
Numerical simulation of vortical flows in the near field of jets from notched circular nozzles
Liu, Feng
Numerical simulation of vortical flows in the near field of jets from notched circular nozzles Keywords: Jet Vortex Computational fluid dynamics Direct numerical simulation Non-circular nozzles a b s t r a c t The vortex dominated flows in the near field of jets from notched circular nozzles
Raman, Sethu
(HIC) associated with an urban area can significantly alter lower tropospheric winds and lowObservations and Numerical Simulations of Urban Heat Island and Sea Breeze Circulations over New disaster on September 11, 2001. An ARPS model numerical simulation was conducted to explore the complex
Mahesh, Krishnan
Upstream entrainment in numerical simulations of spatially evolving round jets Pradeep C. Babu) Direct numerical simulation is used to study the effect of entrainment near the inflow nozzle on spatially evolving round jets. Inflow entrainment is obtained by providing a buffer region upstream
The matching of 3D Rolie-Poly viscoelastic numerical simulations with experimental polymer melt flow
Jimack, Peter
Kingdom J. Embery and D. Auhl IRC in Polymer Science and Technology, Department of Physics and AstronomyThe matching of 3D Rolie-Poly viscoelastic numerical simulations with experimental polymer melt of commercial viscoelastic polymer melts. Numerical simulation techniques have steadily advanced over the last
Field Survey and Numerical Simulations: A Review of the 1998 Papua New Guinea Tsunami
Lynett, Patrick
Field Survey and Numerical Simulations: A Review of the 1998 Papua New Guinea Tsunami PATRICK J (PNG) tsunami of 1998 is re-examined through a detailed review of the field survey as well as numerous of frequency dispersion on the landslide-generated tsunami. The numerical comparisons indicate that the NLSW
Numerical simulation of micro-fluidic passive and active mixers
Kumar, Saurabh
2002-01-01
the flow rate. Hence, output channels exhibit predetermined concentration values, which allow concentration dependent chemistry experiments in each output channel. Convective diffusive transport in this micro mixer is studied numerically and theoretically...
Numerical Simulations of Gamma-Ray Burst Explosions
Lazzati, Davide; López-Cámara, Diego
2015-01-01
Gamma-ray bursts are a complex, non-linear system that evolves very rapidly through stages of vastly different conditions. They evolve from scales of few hundred kilometers where they are very dense and hot to cold and tenuous on scales of parsecs. As such, our understanding of such a phenomenon can truly increase by combining theoretical and numerical studies adopting different numerical techniques to face different problems and deal with diverse conditions. In this review, we will describe the tremendous advancement in our comprehension of the bursts phenomenology through numerical modeling. Though we will discuss studies mainly based on jet dynamics across the progenitor star and the interstellar medium, we will also touch upon other problems such as the jet launching, its acceleration, and the radiation mechanisms. Finally, we will describe how combining numerical results with observations from Swift and other instruments resulted in true understanding of the bursts phenomenon and the challenges still lyi...
13.4 A HIGH RESOLUTION NUMERICAL SIMULATION OF THE LANDFALL OF HURRICANE OPAL (1995)
Wilhelmson, Robert
1995-01-01
13.4 A HIGH RESOLUTION NUMERICAL SIMULATION OF THE LANDFALL OF HURRICANE OPAL (1995) Glen Romine at: http://pampa.ncsa.uiuc.edu/~romine/opal.html Recent high-resolution simulations within a high-resolution (1.1 km) simulation of Hurricane Opal (1995) carried out using the MM5. The primary
NUMERICAL SIMULATION OF TRACER TESTS IN HETEROGENEOUS AQUIFER
Jiao, Jiu Jimmy
of the hydraulic conductivity using borehole flowmeters in a total of 49 fully penetrating wells, Rehfeldt et al. is simulated using three-dimensional (3D) hydraulic conductivity distributions derived from the borehole flow- meter test data. The simulated plume is more sensitive to the way the hydraulic conductivity field
Numerical thermalization in particle-in-cell simulations with Monte-Carlo collisions
Lai, P. Y.; Lin, T. Y.; Lin-Liu, Y. R.; Chen, S. H.
2014-12-15
Numerical thermalization in collisional one-dimensional (1D) electrostatic (ES) particle-in-cell (PIC) simulations was investigated. Two collision models, the pitch-angle scattering of electrons by the stationary ion background and large-angle collisions between the electrons and the neutral background, were included in the PIC simulation using Monte-Carlo methods. The numerical results show that the thermalization times in both models were considerably reduced by the additional Monte-Carlo collisions as demonstrated by comparisons with Turner's previous simulation results based on a head-on collision model [M. M. Turner, Phys. Plasmas 13, 033506 (2006)]. However, the breakdown of Dawson's scaling law in the collisional 1D ES PIC simulation is more complicated than that was observed by Turner, and the revised scaling law of the numerical thermalization time with numerical parameters are derived on the basis of the simulation results obtained in this study.
Numerical simulations of supercell interactions with thermal boundaries
Kay, Michael Paul
1999-01-01
to examine the effects of the interaction of simulated supercede thunderstorms with thermal boundaries on storm morphology and low-level rotation. This study differs from previous supercede modeling studies that use homogeneous initial conditions. A non...
Numerical simulation of tsunami waves generated by deformable submarine landslides
Kirby, James T.
wave model Tsunami wave Numerical modeling a b s t r a c t This paper presents a new submarine energy is mostly concentrated on a narrow band of the dominant slide direction for the waves generated-up along the coast. For example, submarine mass failure is considered as one of the major sources
Direct Numerical Simulation of Solid Deformation During Dendritic Solidification
Beckermann, Christoph
solidification is a common phe- nomenon in metal casting and can lead to defects such as hot tears, macro is caused by external forces, for example through the rolls in continuous casting, mold wall movement of the mush can lead to numerous defects in a solidified casting, including hot tears, macrosegregation
Numerical Simulation of Groundwater Withdrawal at the Nevada Test Site
Carroll, Rosemary; Giroux, Brian; Pohll, Greg; Hershey, Ronald; Russell, Charles; Howcroft, William
2004-01-28
Alternative uses of the Nevada Test Site (NTS) may require large amounts of water to construct and/or operate. The only abundant source of water at the NTS is groundwater. This report describes preliminary modeling to quantify the amount of groundwater available for development from three hydrographic areas at the NTS. Modeling was conducted with a three-dimensional transient numerical groundwater flow model.
Course: Numerical Simulation in Applied Geophysics. From the Mesoscale to the Macroscale
Santos, Juan
Course: Numerical Simulation in Applied Geophysics. From the Mesoscale to the Macroscale Professor variations in the fluid and solid matrix properties, fine layering, frac- tures and craks at the mesoscale
Mass and charge flow in nanopores: numerical simulation via mesoscale models
Cecconi, Fabio
Mass and charge flow in nanopores: numerical simulation via mesoscale models Mauro Chinappi1 at nanoscale is here addressed via a recent developed mesoscale approach. In particular the flow
NUMERICAL SIMULATION OF ELECTROMECHANICAL DYNAMICS IN PACED CARDIAC TISSUE Xiaopeng Zhao
Zhao, Xiaopeng
NUMERICAL SIMULATION OF ELECTROMECHANICAL DYNAMICS IN PACED CARDIAC TISSUE Henian Xia Xiaopeng Zhao of Tennessee Knoxville, TN 37996 kwong@utk.edu ABSTRACT We study electromechanical dynamics in paced cardiac physics fields are integrated, including electrophysiology, electromechanics, and mechanoelectrical
Ravago Bastardo, Delmira Cristina
2005-08-29
The main objective of this research is to compare the performance of cyclic steam injection using horizontal wells based on the analytical model developed by Gunadi against that based on numerical simulation. For comparison, a common reservoir...
Roy, Subrata
1 American Institute of Aeronautics and Astronautics Numerical Simulation of a Gas Turbine of combustion by using nanosecond pulsed plasma actuators for a gas turbine combustor. Moreau [2] and Corke et
Numerical simulation of the hydrodynamical combustion to strange quark matter
Niebergal, Brian; Ouyed, Rachid; Jaikumar, Prashanth
2010-12-15
We present results from a numerical solution to the burning of neutron matter inside a cold neutron star into stable u,d,s quark matter. Our method solves hydrodynamical flow equations in one dimension with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change from heat released in forming the stable quark phase. Our numerical results suggest burning front laminar speeds of 0.002-0.04 times the speed of light, much faster than previous estimates derived using only a reactive-diffusive description. Analytic solutions to hydrodynamical jump conditions with a temperature-dependent equation of state agree very well with our numerical findings for fluid velocities. The most important effect of neutrino cooling is that the conversion front stalls at lower density (below {approx_equal}2 times saturation density). In a two-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.
HEP/123-qed Numerical simulation of deformable drops with soluble
-matrix interfaces and in the bulk fluids using a novel 3D adaptive finite-element method. The method is based. For clean drops (no surfactant), our simulations confirm (for the first time to our knowledge) a well known decreasing Cac with respect to the clean-drop case. However, at large coverages close to the maximum packing
Numerical Simulation of Pulse-Tube Refrigerators: 1D model I.A. Lyulina1
Eindhoven, Technische Universiteit
of a piston, an aftercooler (AC), a regenerator, a cold heat exchanger (CHX), a tube, a hot heat exchanger numerical model has been introduced to study steady oscillatory heat and mass transfer in the tube section, numerical simulation, high resolution scheme 1 Introduction The pulse tube is a relatively new type
Ismagilov, Rustem F.
Effects of Shear Rate on Propagation of Blood Clotting Determined Using Microfluidics and Numerical-ismagilov@uchicago.edu Abstract: This paper describes microfluidic experiments with human blood plasma and numerical simulations removed. In addition, these results demonstrate the utility of simplified mechanisms and microfluidics
A Simulation and Decision Framework for Selection of Numerical Solvers in Scientific Computing
Burns, Peter
A Simulation and Decision Framework for Selection of Numerical Solvers in Scientific Computing by the journal ACM Transactions On Mathematical Software (ACM 2004 [1]) and the Numerical Recipes published Peter Bunus Department of Computer and Information Science Linköping University, Sweden petbu
NUMERICAL SIMULATIONS OF LONG TERM UNSATURATED FLOW AND ACID MINE DRAINAGE AT WASTE ROCK PILES
Aubertin, Michel
NUMERICAL SIMULATIONS OF LONG TERM UNSATURATED FLOW AND ACID MINE DRAINAGE AT WASTE ROCK PILES Omar present a numerical modeling study of unsaturated water flow and acid mine drainage in idealized (but of oxygen diffusion and acid mine drainage through the waste rock piles showed that oxygen is generally
Numerical Investigation of a Transverse Jet in a Supersonic Crossflow using Large Eddy Simulation
Paris-Sud XI, Université de
Numerical Investigation of a Transverse Jet in a Supersonic Crossflow using Large Eddy Simulation injected fuel jets in hot supersonic crossflows. This paper describes the numerical algorithm being used into a supersonic crossflow computed on a coarse mesh. These results are discussed and similarity
Kirby, James T.
Numerical simulation of the 2011 Tohoku tsunami: Comparison with field observations and sensitivity history, created a major tsunami that caused numerous deaths and enormous destruction on the nearby Hon- shu coast. Various tsunami sources were developed for this event, based on inverting seismic or GPS
Numerical simulation of survey misalignment effects in the ATA structure
Close, E.R.
1981-02-01
A computer program MSALIGN incorporating solenoidal magnet positioning errors, survey alignment errors, and structure support sag has been written and used to simulate the Advanced Test Accelerator (ATA) inorder to investigate the effects of errors on the transported beam. Runs using up to 10K particles to represent the beam were made over ensembles of up to 100 misaligned machines. They show that for the ATA design tolerances the resultant beam steering is acceptable and easily corrected using steering magnets. Also, that for changes within a factor of 2 to 3 over design values the variation is linear. The program MSALIGN is general in design. Given the appropriate misalignment procedure it can simulate other machines or study other types of errors.
Numerical simulation of optical feedback on a quantum dot lasers
Al-Khursan, Amin H., E-mail: ameen_2all@yahoo.com [Thi-Qar University, Nassiriya Nanotechnology Research Laboratory (NNRL), Science College (Iraq); Ghalib, Basim Abdullattif [Babylon University, Laser Physics Department, Science College for Women (Iraq); Al-Obaidi, Sabri J. [Al-Mustansiriyah University, Physics Department, Science College (Iraq)
2012-02-15
We use multi-population rate equations model to study feedback oscillations in the quantum dot laser. This model takes into account all peculiar characteristics in the quantum dots such as inhomogeneous broadening of the gain spectrum, the presence of the excited states on the quantum dot and the non-confined states due to the presence of wetting layer and the barrier. The contribution of quantum dot groups, which cannot follow by other models, is simulated. The results obtained from this model show the feedback oscillations, the periodic oscillations which evolves to chaos at higher injection current of higher feedback levels. The frequency fluctuation is attributed mainly to wetting layer with a considerable contribution from excited states. The simulation shows that is must be not using simple rate equation models to express quantum dots working at excited state transition.
OTC 23597-MS Numerical Simulation of Floating Offshore Wind Turbines Including Aero-
Sweetman, Bert
OTC 23597-MS Numerical Simulation of Floating Offshore Wind Turbines Including Aero- Elasticity methodology is presented for simulation of dynamic behavior of floating offshore wind turbines. Wind forces. Introduction and Background The economic potential of offshore deep water wind turbines has not yet been fully
Three dimensional numerical simulations of the UPS-292-SC engine
O'Rourke, P.J.; Amsden, A.A.
1987-01-01
We present and analyze three-dimensional calculations of the spray, mixing and combustion in the UPS-292 stratified charge engine for three different operating conditions, corresponding to overall air-fuel ratios between 22.4 and 61.0. The numerical calculations are performed with KIVA, a multidimensional arbitrary-mesh, finite-difference hydrodynamics program for internal combustion engine applications. The calculations use a mesh of 10,000 computational cells, which conform to the shape of the piston bowl and cylinder and move to follow piston motion. Each operating condition is calculated from intake valve closure at 118/sup 0/ BTDC to 90/sup 0/ ATDC and requires approximately three hours of CRAY-XMP computer time.
Numerical Simulations of Leakage from Underground LPG Storage Caverns
Yamamoto, Hajime; Pruess, Karsten
2004-09-01
To secure a stable supply of petroleum gas, underground storage caverns for liquified petroleum gas (LPG) are commonly used in many countries worldwide. Storing LPG in underground caverns requires that the surrounding rock mass remain saturated with groundwater and that the water pressure be higher than the liquid pressure inside the cavern. In previous studies, gas containment criteria for underground gas storage based on hydraulic gradient and pressure have been discussed, but these studies do not consider the physicochemical characteristics and behavior of LPG such as vaporization and dissolution in groundwater. Therefore, while these studies are very useful for designing storage caverns, they do not provide better understanding of the either the environmental effects of gas contamination or the behavior of vaporized LPG. In this study, we have performed three-phase fluid flow simulations of gas leakage from underground LPG storage caverns, using the multiphase multicomponent nonisothermal simulator TMVOC (Pruess and Battistelli, 2002), which is capable of solving the three-phase nonisothermal flow of water, gas, and a multicomponent mixture of volatile organic chemicals (VOCs) in multidimensional heterogeneous porous media. A two-dimensional cross-sectional model resembling an actual underground LPG facility in Japan was developed, and gas leakage phenomena were simulated for three different permeability models: (1) a homogeneous model, (2) a single-fault model, and (3) a heterogeneous model. In addition, the behavior of stored LPG was studied for the special case of a water curtain suddenly losing its function because of operational problems, or because of long-term effects such as clogging of boreholes. The results of the study indicate the following: (1) The water curtain system is a very powerful means for preventing gas leakage from underground storage facilities. By operating with appropriate pressure and layout, gas containment can be ensured. (2) However , in highly heterogeneous media such as fractured rock and fault zones, local flow paths within which the gas containment criterion is not satisfied could be formed. To eliminate such zones, treatments such as pre/post grouting or an additional installment of water-curtain boreholes are essential. (3) Along highly conductive features such as faults, even partially saturated zones possess certain effects that can retard or prevent gas leakage, while a fully unsaturated fault connected to the storage cavern can quickly cause a gas blowout. This possibility strongly suggests that ensuring water saturation of the rock surrounding the cavern is a very important requirement. (4) Even if an accident should suddenly impair the water curtain, the gas plume does not quickly penetrate the ground surface. In these simulations, the plume takes several months to reach the ground surface.
Evaluation of Residential Hot Water Distribution Ssytems by Numeric Simulation
Wendt, ROBERT
2005-08-17
The objective of this project was to evaluate the performance and economics of various domestic hot water distribution systems in representative California residences. While the greatest opportunities for improved efficiency occur in new construction, significant improvements can also be made in some existing distribution systems. Specific objectives of the project tasks were: (1) Simulate potential energy savings of, perform cost-benefit analyses of, and identify market barriers to alternative new systems. (2) Simulate potential energy savings of, perform cost-benefit analyses of, and identify market barriers to maintenance, repair, and retrofit modifications of existing systems. (3) Evaluate potential impact of adopting alternative hot water distribution systems and report project findings. The outcome of this project is to provide homeowners, homebuilders, systems suppliers, municipal code officials and utility providers (both electric and water/sewer) with a neutral, independent, third party, cost-benefit analysis of alternative hot water distribution systems for use in California. The results will enable these stakeholders to make informed decisions regarding which system is most appropriate for use.
On numerical turbulence generation for test-particle simulations
Tautz, R. C. [Zentrum fuer Astronomie und Astrophysik, Technische Universitaet Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany); Dosch, A. [Center for Space Plasmas and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, Alabama 35805 (United States)
2013-02-15
A modified method is presented to generate artificial magnetic turbulence that is used for test-particle simulations. Such turbulent fields are obtained from the superposition of a set of wave modes with random polarizations and random directions of propagation. First, it is shown that the new method simultaneously fulfils requirements of isotropy, equal mean amplitude and variance for all field components, and vanishing divergence. Second, the number of wave modes required for a stochastic particle behavior is investigated by using a Lyapunov approach. For the special case of slab turbulence, it is shown that already for 16 wave modes the particle behavior agrees with that shown for considerably larger numbers of wave modes.
On the relevance of numerical simulations to booming sand
Patrick Richard; Sean Mcnamara; Merline Tankeo
2012-01-04
We have performed a simulation study of 3D cohesionless granular flows down an inclined chute. We find that the oscillations observed in [L.E. Silbert, Phys. Rev. Lett., 94, 098002 (2005)] near the angle of repose are harmonic vibrations of the lowest normal mode. Their frequencies depend on the contact stiffness as well as on the depth of the flow. Could these oscillations account for the phenomena of "booming sand"? We estimate an effective contact stiffness from the Hertz law, but this leads to frequencies several times higher than observed. However, the Hertz law also predicts interpenetrations of a few nanometers, indicating that the oscillations frequencies are governed by the surface stiffness, which can be much lower than the bulk one. This is in agreement with previous studies ascribing the ability to sing to the presence of a soft coating on the grain surface.
Numerical simulation of plasma heating of a composite powder particle
Demetriou, M.D.; Lavine, A.S.; Ghoniem, N.M.
1999-07-01
The use of fine composite powder particles (composed of a ceramic core and a metallic coating) in plasma spraying processes is desirable in developing thin film coatings that possess high abrasion as well as high fracture resistance. Quantitative knowledge of the thermal behavior of a composite particle in a plasma beam is essential in optimizing the process variables to achieve uniform melting of the coating material. In this work, a numerical model is developed to analyze the in-flight thermal behavior of a spherically symmetric WC-Co composite particle travelling in an argon arc-jet DC plasma under strongly unsteady plasma conditions. The model gives quantitative as well as qualitative information about the thermal response of the heated particle. The important features that are addressed are the temperature response of the particle; the history of the location of the melting and vaporization fronts; and the physical state of the particle at the end of its flight. For the conditions investigated, it was determined that the internal conduction resistance is negligible as compared to the net external resistance. However, the presence of the ceramic base was found to affect the transient heating process since its content in the particle composition determines the time constant of the process. Another interesting observation is that proper selection of the particle injection speed and injection location can be effective means for optimizing the heating process and achieving uniform melting of the coating material.
The Numerical Simulation Of A Transitional Flow In The VKI-GENOA Turbine Cascade
Yershov, Sergiy; Yakovlev, Viktor; Gryzun, Maria
2015-01-01
This study presents a numerical simulation of a 3D viscous flow in the VKI-Genoa cascade that takes into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes equations and the two-equation k-omega SST turbulence model. The algebraic Production Term Modification model is used for modeling the laminar-turbulent transition. Computations of both fully turbulent and transitional flows are carried out. The contours of the Mach number, the turbulence kinetic energy, the entropy function, as well as limiting streamlines are presented. The analysis of the numerical results demonstrates the influence of the laminar-turbulent transition on the secondary flow pattern. The comparison between the present computational results and the existing experimental and numerical data shows that the proposed approach reflects sufficiently the physics of the laminar-turbulent transition in turbine cascades.
Numerical simulation of flow distribution for pebble bed high temperature gas cooled reactors
Yesilyurt, Gokhan
2004-09-30
to be investigated. No detailed complete calculations for this kind of reactor to address these local phenomena are available. This work is an attempt to bridge this gap by evaluating this effect. I.2 TURBULENCE MODEL SELECTION The simulation of these local... number of numerical studies on flows around spherical bodies, none of them use the necessary turbulence models that are required to simulate flow where strong separation exists. With the development of high performance computers built for applications...
McKenzie, Jeffrey M.
Groundwater flow with energy transport and waterice phase change: Numerical simulations saturated, coupled porewater-energy transport, with freezing and melting porewater, and includes propor for groundwater and energy transport with ice formation and melting are proposed that may be used by other
Wang, Yuqing
0 Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated is eventually dissipated due to surface friction. Since the energy production rate is a linear function while intensifies. When the dissipation rate eventually reaches the production rate, the TC has no excess energy
Wang, Yuqing
Energy Production, Frictional Dissipation, and Maximum Intensity of a Numerically Simulated is eventually dissipated due to surface friction. Since the energy production rate is a linear function while intensifies. When the dissipation rate eventually reaches the production rate, the TC has no excess energy
Kochevsky, A N
2005-01-01
The paper describes capabilities of numerical simulation of liquid flows with solid and/or gas admixtures in centrifugal pumps using modern commercial CFD software packages, with the purpose to predict performance curves of the pumps treating such media. In particular, the approaches and multiphase flow models available in the package CFX-5 are described; their advantages and disadvantages are analyzed.
TONUS TOkamaks and NUmerical Simulations Inria project-team in Strasbourg.
Helluy, Philippe
TONUS TOkamaks and NUmerical Simulations Inria project-team in Strasbourg. IRMA (CNRS UMR 7501 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Tokamak plasma modeling 8 3.1 Controlled fusion and ITER in confining a very hot hydrogen plasma inside a toroidal chamber, called a tokamak. In addition to physics
Acoustic pulse propagation in an urban environment using a three-dimensional numerical simulation
North Carolina at Chapel Hill, University of
- cally complex problem that has many practical applications. In urban planning and city design, acoustic and scattering play a significant role in acoustic energy transport in urban areas, especially in cases whenAcoustic pulse propagation in an urban environment using a three-dimensional numerical simulation
Cloud patterns lee of Hawaii Island: A synthesis of satellite observations and numerical simulation
Xie, Shang-Ping
Cloud patterns lee of Hawaii Island: A synthesis of satellite observations and numerical simulation; accepted 29 April 2008; published 15 August 2008. [1] Standing well above the trade wind inversion, Hawaii. To illustrate the circulation effect, lee cloud formation is compared between tall Hawaii and short Kauai
Numerical simulation of detonation processes in a variable cross-section chamber
Texas at Arlington, University of
in a combustion chamber with variable cross- sections are numerically simulated for a hydrogenair reacting flow facilities [2]. The pri- mary advantage of detonation combustion as com- pared to deflagration is its rapid energy release. This rapid energy release allows the design of pulse detona- tion engines with high
Numerical simulations of dense clouds on steep slopes: Application to powder-snow avalanches
Saramito, Pierre
Numerical simulations of dense clouds on steep slopes: Application to powder-snow avalanches results. The interest of the results for powder- snow avalanches is discussed, concluding that two. Introduction A powder-snow avalanche is a dense cloud of suspended snow particles moving down a steep slope
Numerical Simulation of Mesoscale Circulations in a Region of Contrasting Soil Types
Raman, Sethu
Numerical Simulation of Mesoscale Circulations in a Region of Contrasting Soil Types SETHU RAMAN,1 AARON SIMS,1,2 ROBB ELLIS,1 and RYAN BOYLES 1 Abstract--Mesoscale processes that form due to changes on mesoscale processes are examined. Climatological analyses indicate increased convective precipitation
American Institute of Aeronautics and Astronautics Numerical Simulation of Detonation Processes in a
Texas at Arlington, University of
The detonation processes occurring in a combustion chamber with variable cross-sections are numerically simulated, such as in propulsion1 and in high-enthalpy ground test facilities. 2 The primary advantage of detonation combustion can be sought for the above-mentioned applications. Time-accurate computational fluid dynamics (CFD
Schlegel, H. Bernhard
A Numerical Simulation of Nonadiabatic Electron Excitation in the Strong Field Regime: Linear of the electronic optical response of a series of linear polyenes in strong laser fields. Ethylene, butadiene and 760 nm. Time evolution of the electron population indicates not only the electrons, but also lower
Towards Numerical Simulation of Cavitating Flows in Complex M. Mattson and K. Mahesh
Mahesh, Krishnan
Towards Numerical Simulation of Cavitating Flows in Complex Geometries M. Mattson and K. Mahesh (Aerospace Engineering and Mechanics, University of Minnesota) 27th Symposium on Naval Hydrodynamics Seoul of bubbles in complex geometries, with specific applica- tion to modeling cavitation instabilities
Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass
Miller, Richard S.
Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass R. S is performed in order to evaluate the performance and optimal operating conditions of vortex pyrolysis reactors particle pyrolysis is coupled with a compressible Reynolds stress transport model for the turbulent reactor
PHYSICS OF FLUIDS 24, 103306 (2012) Numerical simulation of turbulent sediment transport,
Claudin, Philippe
2012-01-01
PHYSICS OF FLUIDS 24, 103306 (2012) Numerical simulation of turbulent sediment transport, from bed October 2012) Sediment transport is studied as a function of the grain to fluid density ratio using two), vertical velocities are so small that sediment transport occurs in a thin layer at the surface
Ducted Turbine Blade Optimization Using Numerical Simulation Michael Shives and Curran Crawford
Pedersen, Tom
Ducted Turbine Blade Optimization Using Numerical Simulation Michael Shives and Curran Crawford analysis and optimization of ducted turbines. The model is similar to standard blade element momentum. This eliminates many assumptions used in applying the typical blade element momentum (BEM) theory to a turbine
Numerical simulations of radon as an in situ partitioning tracer for quantifying NAPL
Semprini, Lewis
Numerical simulations of radon as an in situ partitioning tracer for quantifying NAPL contaminationpull partitioning tracer tests using radon-222 to quantify non- aqueous phase liquid contamination. J. Contam. Hydrol. 58, 129146] of pushpull tests using radon as a naturally occurring partitioning tracer
Fringer, Oliver B.
Threedimensional, nonhydrostatic numerical simulation of nonlinear internal wave generation in the Luzon Strait. A wave generation is stronger in the southern portion of the Luzon Strait because diurnal internal tidal beams augment the amplitude of the semidiurnal A waves. B wave generation is stronger
Modeling and Numerical Simulation of Bioheat Transfer and Biomechanics in Soft Tissue
Zhang, Jun
Modeling and Numerical Simulation of Bioheat Transfer and Biomechanics in Soft Tissue #3; Wensheng techniques are eÆcient. Key words: Bioheat transfer, biomechanics, discretization, iterative solver. 1 do in engineering area by solving constitutive equations. One of the major diÆculties in biomechanics
Numerical Simulation of the December 26, 2004 Indian Ocean Tsunami using a Boussinesq model
Kirby, James T.
tsunami education or tsunami warning system in the re- gion exaccerbated the number of fatalities, even. Scientists had been warning of the growing exposure of coastal residents to tsunami hazards for yearsNumerical Simulation of the December 26, 2004 Indian Ocean Tsunami using a Boussinesq model Philip
Numerical methods for the simulation of salt migration in regional groundwater
Vuik, Kees
Numerical methods for the simulation of salt migration in regional groundwater flow E.S. van Baaren . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2.3 Groundwater flow equation . . . . . . . . . . . . . . . . . 10 2.3 Solute transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.2.2 Groundwater equation . . . . . . . . . . . . . . . . . . . . 20 3.2.3 Solute transport
Fleck, Norman A.
2005-01-01
in gas turbines for propulsion and power generation [14]. The systems are susceptible to performanceMaterials Science and Engineering A 404 (2005) 2632 Numerical simulations of crack formation from pegs in thermal barrier systems with NiCoCrAlY bond coats H.X. Zhua, N.A. Flecka,, A.C.F. Cocksb, A
Numerical Simulations of the Wave Bottom Boundary Layer over Sand Ripples
Slinn, Donald
Numerical Simulations of the Wave Bottom Boundary Layer over Sand Ripples by Thomas Pierro A Thesis over sand ripples, and to compare the results with flows over a smooth bed to determine how wave energy energy dissipation rates are quantified and a better understanding of oscillatory flow over sand ripples
Numerical Simulations Reveal the Origin of QPOs in Black Hole Candidates
Sandip K. Chakrabarti
2005-01-14
We present results of various types of numerical simulations of black hole accretion disks and find that those flows which are relatively non-dissipative and which contain accretion shocks are the best candidates so far. The power density spectra (PDS) reveal the aspects which are similar to what are observed in black hole candidates.
Numerical Simulation and Multiple Realizations for Sensitivity Study of Shale Gas Reservoir
Mohaghegh, Shahab
SPE 141058 Numerical Simulation and Multiple Realizations for Sensitivity Study of Shale Gas. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract Shale gas in the United States the largest conventional gas accumulations in the world. Shale gas success is directly the result
Numerical simulation of air/water multiphase flows for ceramic sanitary ware design by multiple GPUs
8 Numerical simulation of air/water multiphase flows for ceramic sanitary ware design by multiple and manufacturing of plumbing products such as ceramic sanitary wares. In order to re-produce the complex/water multiphase flows for ceramic sanitary ware design by multiple GPUs Being a world-wide leading company, TOTO
Numerical simulation of a thermoacoustic couple A. I. Abd El-Rahmana
Paris-Sud XI, Université de
Numerical simulation of a thermoacoustic couple A. I. Abd El-Rahmana and E. Abdel-filled half-wavelength thermoacoustic refrigerator. The finite volume method is used, and the solid and air in thermoacoustic refrigerators, characterizing and optimizing their performance, and building models
Numerical simulation of breaking waves by a multi-scale turbulence model
Zhao, Qun
and diffusion are of the same order at the trough level. Above the trough level, turbulent convection dominates-dimensional MAC type finite difference method. The third-order upwind scheme proposed by Kawamura and KawaharaNumerical simulation of breaking waves by a multi-scale turbulence model Qun Zhaoa,*, Steve
Numerical simulation of wire-coating: the influence of temperature boundary conditions
Wapperom, Peter
Numerical simulation of wire-coating: the influence of temperature boundary conditions Peter-2800 Lyngby (Danmark) Abstract A finite element program has been used to analyze the wire-coating and power-law index will be examined. Keywords: polymeric fluids; wire coating; Carreau model; nonisothermal
Numeric Simulation of Heat Transfer and Electrokinetic Flow in an Electroosmosis-Based
Le Roy, Robert J.
Numeric Simulation of Heat Transfer and Electrokinetic Flow in an Electroosmosis-Based Continuous is dedicated to under- standing the fluid flow and heat transfer mechanisms occurring in continuous flow PCR are discussed in detail. The importance of each heat transfer mechanism for different situations is also
Direct numerical simulation of turbulent heat transfer in annuli: effect of heat flux ratio.
Paris-Sud XI, Université de
Direct numerical simulation of turbulent heat transfer in annuli: effect of heat flux ratio. M-la-Vall´ee cedex 2, France (Dated: October 23, 2008) Abstract Fully developed turbulent flow and heat transfer square (rms) of temperature fluctuations, turbulent heat fluxes, heat transfer, ...). To validate
Numerical Simulation of Horizontal Continuous Casting Process of C194 Copper Alloy
Huang Guojie; Xie Shuisheng; Cheng Lei; Cheng Zhenkang [State Key Laboratory for Fabrication and Processing of Nonferrous Metals, Beijing General Research Institute for Non-ferrous Metals, China, 100088 (China)
2007-05-17
Horizontal Continuous Casting (H.C.C) is an important method to cast C194 copper ingot. In this paper, numerical simulation is adopted to investigate the casting process in order to optimize the H.C.C technical parameters, such as the casting temperature, casting speed and cooling intensity. According to the numerical results, the reasonable parameters are that the casting temperature is between 1383K{approx}1463K, the casting speed is between 7.2m/h{approx}10.8m/h and the speed of cooling water is between 3.6m/s{approx}4.6m/s. The results of numerical simulation provide the significant reference to the subsequent experiments.
Numerical simulations of multi-shell plasma twisters in the solar atmosphere
Murawski, K; Musielak, Z E; Dwivedi, B N
2015-01-01
We perform numerical simulations of impulsively generated Alfv\\'en waves in an isolated photospheric flux tube, and explore the propagation of these waves along such magnetic structure that extends from the photosphere, where these waves are triggered, to the solar corona, and analyze resulting magnetic shells. Our model of the solar atmosphere is constructed by adopting the temperature distribution based on the semi-empirical model and specifying the curved magnetic field lines that constitute the magnetic flux tube which is rooted in the solar photosphere. The evolution of the solar atmosphere is described by 3D, ideal magnetohydrodynamic equations that are numerically solved by the FLASH code. Our numerical simulations reveal, based on the physical properties of the multi-shell magnetic twisters and the amount of energy and momentum associated with them, that these multi-shell magnetic twisters may be responsible for the observed heating of the lower solar corona and for the formation of solar wind. Moreov...
2D numerical simulation of the MEP energy-transport model with a finite difference scheme
Romano, V. . E-mail: romano@dmi.unict.it
2007-02-10
A finite difference scheme of Scharfetter-Gummel type is used to simulate a consistent energy-transport model for electron transport in semiconductors devices, free of any fitting parameters, formulated on the basis of the maximum entropy principle. Simulations of silicon n{sup +}-n-n{sup +} diodes, 2D-MESFET and 2D-MOSFET and comparisons with the results obtained by a direct simulation of the Boltzmann transport equation and with other energy-transport models, known in the literature, show the validity of the model and the robustness of the numerical scheme.
Sagert, I; Fattoyev, F J; Postnikov, S; Horowitz, C J
2015-01-01
Neutron star and supernova matter at densities just below the nuclear matter saturation density is expected to form a lattice of exotic shapes. These so-called nuclear pasta phases are caused by Coulomb frustration. Their elastic and transport properties are believed to play an important role for thermal and magnetic field evolution, rotation and oscillation of neutron stars. Furthermore, they can impact neutrino opacities in core-collapse supernovae. In this work, we present proof-of-principle 3D Skyrme Hartree-Fock (SHF) simulations of nuclear pasta with the Multi-resolution ADaptive Numerical Environment for Scientific Simulations (MADNESS). We perform benchmark studies of $^{16} \\mathrm{O}$, $^{208} \\mathrm{Pb}$ and $^{238} \\mathrm{U}$ nuclear ground states and calculate binding energies via 3D SHF simulations. Results are compared with experimentally measured binding energies as well as with theoretically predicted values from an established SHF code. The nuclear pasta simulation is initialized in the so...
Analysis of the flamelet concept in the numerical simulation of laminar partially premixed flames
Consul, R.; Oliva, A.; Perez-Segarra, C.D.; Carbonell, D.; de Goey, L.P.H.
2008-04-15
The aim of this work is to analyze the application of flamelet models based on the mixture fraction variable and its dissipation rate to the numerical simulation of partially premixed flames. Although the main application of these models is the computation of turbulent flames, this work focuses on the performance of flamelet concept in laminar flame simulations removing, in this way, turbulence closure interactions. A well-known coflow methane/air laminar flame is selected. Five levels of premixing are taken into account from an equivalence ratio {phi}={infinity} (nonpremixed) to {phi}=2.464. Results obtained using the flamelet approaches are compared to data obtained from the detailed solution of the complete transport equations using primitive variables. Numerical simulations of a counterflow flame are also presented to support the discussion of the results. Special emphasis is given to the analysis of the scalar dissipation rate modeling. (author)
A new dipolar potential for numerical simulations of polar fluids on the 4D hypersphere
Caillol, Jean-Michel; Trulsson, Martin
2014-09-28
We present a new method for Monte Carlo or Molecular Dynamics numerical simulations of three-dimensional polar fluids. The simulation cell is defined to be the surface of the northern hemisphere of a four-dimensional (hyper)sphere. The point dipoles are constrained to remain tangent to the sphere and their interactions are derived from the basic laws of electrostatics in this geometry. The dipole-dipole potential has two singularities which correspond to the following boundary conditions: when a dipole leaves the northern hemisphere at some point of the equator, it reappears at the antipodal point bearing the same dipole moment. We derive all the formal expressions needed to obtain the thermodynamic and structural properties of a polar liquid at thermal equilibrium in actual numerical simulation. We notably establish the expression of the static dielectric constant of the fluid as well as the behavior of the pair correlation at large distances. We report and discuss the results of extensive numerical Monte Carlo simulations for two reference states of a fluid of dipolar hard spheres and compare these results with previous methods with a special emphasis on finite size effects.
Guidoboni, Giovanna
2007-01-01
J. Non-Newtonian Fluid Mech. 142 (2007) 36Â62 Review On the numerical simulation of Bingham visco-plastic various results and methods concerning the numerical simulation of Bingham visco-plastic flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 2. On the modeling of Bingham viscous plastic flow
Modeling-Computer Simulations | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History ViewMayo, Maryland: Energy ResourcesDec(Pritchett, 2004) | Open Energy
Numerical simulation of alumina spraying in argon-helium plasma jet
Chang, C.H.
1992-01-01
A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)
Numerical simulation of alumina spraying in argon-helium plasma jet
Chang, C.H.
1992-08-01
A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)
Direct numerical simulations of fluid flow, heat transfer and phase changes
Juric, D.; Tryggvason, G.; Han, J.
1997-04-01
Direct numerical simulations of fluid flow, heat transfer, and phase changes are presented. The simulations are made possible by a recently developed finite difference/front tracking method based on the one-field formulation of the governing equations where a single set of conservation equations is written for all the phases involved. The conservation equations are solved on a fixed rectangular grid, but the phase boundaries are kept sharp by tracking them explicitly by a moving grid of lower dimension. The method is discussed and applications to boiling heat transfer and the solidification of drops colliding with a wall are shown.
Modelling and Numerical Simulation of Gas Migration in a Nuclear Waste Repository
Bourgeat, Alain; Smai, Farid
2010-01-01
We present a compositional compressible two-phase, liquid and gas, flow model for numerical simulations of hydrogen migration in deep geological radioactive waste repository. This model includes capillary effects and the gas diffusivity. The choice of the main variables in this model, Total or Dissolved Hydrogen Mass Concentration and Liquid Pressure, leads to a unique and consistent formulation of the gas phase appearance and disappearance. After introducing this model, we show computational evidences of its adequacy to simulate gas phase appearance and disappearance in different situations typical of underground radioactive waste repository.
Rossi, Tuomas P; Sakko, Arto; Puska, Martti J; Nieminen, Risto M
2015-01-01
We present an approach for generating local numerical basis sets of improving accuracy for first-principles nanoplasmonics simulations within time-dependent density functional theory. The method is demonstrated for copper, silver, and gold nanoparticles that are of experimental interest but computationally demanding due to the semi-core d-electrons that affect their plasmonic response. The basis sets are constructed by augmenting numerical atomic orbital basis sets by truncated Gaussian-type orbitals generated by the completeness-optimization scheme, which is applied to the photoabsorption spectra of homoatomic metal atom dimers. We obtain basis sets of improving accuracy up to the complete basis set limit and demonstrate that the performance of the basis sets transfers to simulations of larger nanoparticles and nanoalloys as well as to calculations with various exchange-correlation functionals. This work promotes the use of the local basis set approach of controllable accuracy in first-principles nanoplasmon...
Rider, William; Kamm, J. R.; Tomkins, C. D.; Zoldi, C. A.; Prestridge, K. P.; Marr-Lyon, M.; Rightley, P. M.; Benjamin, R. F.
2002-01-01
We consider the detailed structures of mixing flows for Richtmyer-Meshkov experiments of Prestridge et al. [PRE 00] and Tomkins et al. [TOM 01] and examine the most recent measurements from the experimental apparatus. Numerical simulations of these experiments are performed with three different versions of high resolution finite volume Godunov methods. We compare experimental data with simulations for configurations of one and two diffuse cylinders of SF{sub 6} in air using integral measures as well as fractal analysis and continuous wavelet transforms. The details of the initial conditions have a significant effect on the computed results, especially in the case of the double cylinder. Additionally, these comparisons reveal sensitive dependence of the computed solution on the numerical method.
Numerical simulations of stripping effects in high-intensity hydrogen ion linacs
Carneiro, J.-P.; Mustapha, B.; Ostroumov, P.N.; /Argonne
2008-12-01
Numerical simulations of H{sup -} stripping losses from blackbody radiation, electromagnetic fields, and residual gas have been implemented into the beam dynamics code TRACK. Estimates of the stripping losses along two high-intensity H{sup -} linacs are presented: the Spallation Neutron Source linac currently being operated at Oak Ridge National Laboratory and an 8 GeV superconducting linac currently being designed at Fermi National Accelerator Laboratory.
Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target
Lomov, I; Liu, B; Georgevich, V; Antoun, T
2007-07-31
We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.
Draxl, C.; Churchfield, M.; Mirocha, J.; Lee, S.; Lundquist, J.; Michalakes, J.; Moriarty, P.; Purkayastha, A.; Sprague, M.; Vanderwende, B.
2014-06-01
Wind plant aerodynamics are influenced by a combination of microscale and mesoscale phenomena. Incorporating mesoscale atmospheric forcing (e.g., diurnal cycles and frontal passages) into wind plant simulations can lead to a more accurate representation of microscale flows, aerodynamics, and wind turbine/plant performance. Our goal is to couple a numerical weather prediction model that can represent mesoscale flow [specifically the Weather Research and Forecasting model] with a microscale LES model (OpenFOAM) that can predict microscale turbulence and wake losses.
K. V. Parchevsky; A. G. Kosovichev
2006-12-14
Results of numerical 3D simulations of propagation of acoustic waves inside the Sun are presented. A linear 3D code which utilizes realistic OPAL equation of state was developed by authors. Modified convectively stable standard solar model with smoothly joined chromosphere was used as a background model. High order dispersion relation preserving numerical scheme was used to calculate spatial derivatives. The top non-reflecting boundary condition established in the chromosphere absorbs waves with frequencies greater than the acoustic cut-off frequency which pass to the chromosphere, simulating a realistic situation. The acoustic power spectra obtained from the wave field generated by sources randomly distributed below the photosphere are in good agreement with observations. The influence of the height of the top boundary on results of simulation was studied. It was shown that the energy leakage through the acoustic potential barrier damps all modes uniformly and does not change the shape of the acoustic spectrum. So the height of the top boundary can be used for controlling a damping rate without distortion of the acoustic spectrum. The developed simulations provide an important tool for testing local helioseismology.
Some effects of data base variations on numerical simulations of uranium migration
Carnahan, C.L.
1987-12-01
Numerical simulations of migration of chemicals in the geosphere depend on knowledge of identities of chemical species and on values of chemical equilibrium constants supplied to the simulators. In this work, some effects of variability in assumed speciation and in equilibrium constants were examined, using migration of uranium as an example. Various simulations were done of uranium migration in systems with varying oxidation potential, pH, and mator component content. A simulation including formation of aqueous species UO/sub 2//sup 2 +/, UO/sub 2/CO/sub 3//sup 0/, UO/sub 2/(CO/sub 3/)/sub 2//sup 2 -/, UO/sub 2/(CO/sub 3/)/sub 3//sup 4 -/, (UO/sub 2/)/sub 2/CO/sub 3/(OH)/sub 3//sup -/, UO/sub 2//sup +/, U(OH)/sub 4//sup 0/, and U(OH)/sub 5//sup -/ is compared to simulation excluding formation of UO/sub 2//sup +/ and U(OH)/sub 5//sup -/. These simulations relied on older data bases, and they are compared to a further simulation using recently published data on formation of U(OH)/sub 4//sup 0/, (UO/sub 2/)/sub 2/CO/sub 3/(OH)/sub 3//sup -/, UO/sub 2/(CO/sub 3/)/sub 5//sup 5 -/, and U(CO/sub 3/)/sub 5//sup 6 -/. Significant differences in dissolved uranium concentrations are noted among the simulations. Differences are noted also in precipitation of two solids, USiO/sub 4/(c) (coffinite) and CaUO/sub 4/(c) (calcium uranate), although the solubility products of the solids were not varied in the simulations. 18 refs., 9 figs., 2 tabs.
Two-dimensional numerical simulation of boron diffusion for pyramidally textured silicon
Ma, Fa-Jun Duttagupta, Shubham; Shetty, Kishan Devappa; Meng, Lei; Hoex, Bram; Peters, Ian Marius; Samudra, Ganesh S.
2014-11-14
Multidimensional numerical simulation of boron diffusion is of great relevance for the improvement of industrial n-type crystalline silicon wafer solar cells. However, surface passivation of boron diffused area is typically studied in one dimension on planar lifetime samples. This approach neglects the effects of the solar cell pyramidal texture on the boron doping process and resulting doping profile. In this work, we present a theoretical study using a two-dimensional surface morphology for pyramidally textured samples. The boron diffusivity and segregation coefficient between oxide and silicon in simulation are determined by reproducing measured one-dimensional boron depth profiles prepared using different boron diffusion recipes on planar samples. The established parameters are subsequently used to simulate the boron diffusion process on textured samples. The simulated junction depth is found to agree quantitatively well with electron beam induced current measurements. Finally, chemical passivation on planar and textured samples is compared in device simulation. Particularly, a two-dimensional approach is adopted for textured samples to evaluate chemical passivation. The intrinsic emitter saturation current density, which is only related to Auger and radiative recombination, is also simulated for both planar and textured samples. The differences between planar and textured samples are discussed.
Figueroa, Aldo [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209 (Mexico)] [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209 (Mexico); Meunier, Patrice; Villermaux, Emmanuel [Aix-Marseille Univ., CNRS, Centrale Marseille, IRPHE, Marseille F-13384 (France)] [Aix-Marseille Univ., CNRS, Centrale Marseille, IRPHE, Marseille F-13384 (France); Cuevas, Sergio; Ramos, Eduardo [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, A.P. 34, Temixco, Morelos 62580 (Mexico)] [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, A.P. 34, Temixco, Morelos 62580 (Mexico)
2014-01-15
We present a combination of experiment, theory, and modelling on laminar mixing at large Péclet number. The flow is produced by oscillating electromagnetic forces in a thin electrolytic fluid layer, leading to oscillating dipoles, quadrupoles, octopoles, and disordered flows. The numerical simulations are based on the Diffusive Strip Method (DSM) which was recently introduced (P. Meunier and E. Villermaux, “The diffusive strip method for scalar mixing in two-dimensions,” J. Fluid Mech. 662, 134–172 (2010)) to solve the advection-diffusion problem by combining Lagrangian techniques and theoretical modelling of the diffusion. Numerical simulations obtained with the DSM are in reasonable agreement with quantitative dye visualization experiments of the scalar fields. A theoretical model based on log-normal Probability Density Functions (PDFs) of stretching factors, characteristic of homogeneous turbulence in the Batchelor regime, allows to predict the PDFs of scalar in agreement with numerical and experimental results. This model also indicates that the PDFs of scalar are asymptotically close to log-normal at late stages, except for the large concentration levels which correspond to low stretching factors.
Van Eerten, Hendrik J.; MacFadyen, Andrew I.
2012-06-01
We discuss jet dynamics for narrow and wide gamma-ray burst (GRB) afterglow jets and the observational implications of numerical simulations of relativistic jets in two dimensions. We confirm earlier numerical results that sideways expansion of relativistic jets during the bulk of the afterglow emission phase is logarithmic in time and find that this also applies to narrow jets with half opening angle of 0.05 rad. As a result, afterglow jets remain highly nonspherical until after they have become nonrelativistic. Although sideways expansion steepens the afterglow light curve after the jet break, the jet edges becoming visible dominates the jet break, which means that the jet break is sensitive to the observer angle even for narrow jets. Failure to take the observer angle into account can lead to an overestimation of the jet energy by up to a factor of four. This weakens the challenge posed to the magneter energy limit by extreme events such as GRB090926A. Late-time radio calorimetry based on a spherical nonrelativistic outflow model remains relevant when the observer is approximately on-axis and where differences of a few in flux level between the model and the simulation are acceptable. However, this does not imply sphericity of the outflow and therefore does not translate to high observer angles relevant to orphan afterglows. For more accurate calorimetry and in order to model significant late-time features such as the rise of the counterjet, detailed jet simulations remain indispensable.
Terascale direct numerical simulations of turbulent combustion using S3D
Chen, Jackie; Klasky, Scott A; Hawkes, Evatt R; Sankaran, Ramanan; Choudhary, Alok; Yoo, Chun S; Liao, Wei-keng; Podhorszki, Norbert
2009-01-01
Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory intensive loops in the code. Through the careful application of loop transformations, data reuse in cache is exploited thereby reducing memory bandwidth needs, and hence, improving S3D's nodal performance. To enhance collective parallel I/O in S3D, an MPI-I/O caching design is used to construct a two-stage write-behind method for improving the performance of write-only operations. The simulations generate tens of terabytes of data requiring analysis. Interactive exploration of the simulation data is enabled by multivariate time-varying volume visualization. The visualization highlights spatial and temporal correlations between multiple reactive scalar fields using an intuitive user interface based on parallel coordinates and time histogram. Finally, an automated combustion workflow is designed using Kepler to manage large-scale data movement, data morphing, and archival and to provide a graphical display of run-time diagnostics.
Numerical simulations of impulsively generated Alfvén waves in solar magnetic arcades
Chmielewski, P.; Murawski, K.; Musielak, Z. E.; Srivastava, A. K.
2014-09-20
We perform numerical simulations of impulsively generated Alfvén waves in an isolated solar arcade, which is gravitationally stratified and magnetically confined. We study numerically the propagation of Alfvén waves along the magnetic structure that extends from the lower chromosphere, where the waves are generated, to the solar corona, and analyze the influence of the arcade size and the width of the initial pulses on the wave propagation and reflection. Our model of the solar atmosphere is constructed by adopting the temperature distribution based on the semi-empirical VAL-C model and specifying the curved magnetic field lines that constitute the asymmetric magnetic arcade. The propagation and reflection of Alfvén waves in this arcade is described by 2.5-dimensional magnetohydrodynamic equations that are numerically solved by the FLASH code. Our numerical simulations reveal that the Alfvén wave amplitude decreases as a result of a partial reflection of Alfvén waves in the solar transition region, and that the waves that are not reflected leak through the transition region and reach the solar corona. We also find the decrement of the attenuation time of Alfvén waves for wider initial pulses. Moreover, our results show that the propagation of Alfvén waves in the arcade is affected by the spatial dependence of the Alfvén speed, which leads to phase mixing that is stronger for more curved and larger magnetic arcades. We discuss the processes that affect the Alfvén wave propagation in an asymmetric solar arcade and conclude that besides phase mixing in the magnetic field configuration, the plasma properties of the arcade, the size of the initial pulse, and the structure of the solar transition region all play a vital role in the Alfvén wave propagation.
Naziar, J.; Couch, R.; Davis, M.
1996-01-01
Traditionally, aeropropulsion structural performance and aerodynamic performance have been designed separately and later mated together via flight testing. In today`s atmosphere of declining resources, it is imperative that more productive ways of designing and verifying aeropropulsion performance and structural interaction be made available to the aerospace industry. One method of obtaining a more productive design and evaluation capability is through the use of numerical simulations. Currently, Lawrence Livermore National Laboratory has developed a generalized fluid/structural interaction code known as ALE3D. This code is capable of characterizing fluid and structural interaction for components such as the combustor, fan/stators, inlet and/or nozzles. This code solves the 3D Euler equations and has been applied to several aeropropulsion applications such as a supersonic inlet and a combustor rupture simulation. To characterize aerodynamic-structural interaction for rotating components such as the compressor, appropriate turbomachinery simulations would need to be implemented within the ALE3D structure. The Arnold Engineering Development Center is currently developing a three-dimensional compression system code known as TEACC (Turbine Engine Analysis Compressor Code). TEACC also solves the 3D Euler equations and is intended to simulate dynamic behavior such as inlet distortion, surge or rotating stall. The technology being developed within the TEACC effort provides the necessary turbomachinery simulation for implementation into ALE3D. This paper describes a methodology to combine three-dimensional aerodynamic turbomachinery technology into the existing aerodynamic-structural interaction simulation, ALE3D to obtain the desired aerodynamic and structural integrated simulation for an aeropropulsion system.
Wu, X.; Gao, J.; Wu, W.
2006-01-01
with double heat sources are numerically simulated. The model is verified by experimental data. The results of the study show that thermal stratification characteristics exist in indoor temperature fields. The paper also analyzes the influence of different...
Laprea-Bigott, Marcelo
1976-01-01
SIMULATION OF FLUID DISPLACEMENT IN POROUS MEDIA ? IMPROVED METHODS TO MINIMIZE NUMERICAL DISPERSION AND GRID ORIENTATION EFFECTS A Thesis by MARCELO LAPREA-BIGOTT Submitted to the Graduate College of Texas A8M University in partial... fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1976 Major Subject: Petroleum Engineering SIMULATION OF FLUID DISPLACEMENT IN POROUS MEDIA - IMPROVED METHODS TO MINIMIZE NUMERICAL DISPERSION AND GRID ORIENTATION EFFECTS A...
A review on recent advances in the numerical simulation for coalbed-methane-recovery process
Wei, X.R.; Wang, G.X.; Massarotto, P.; Golding, S.D.; Rudolph, V. [University of Queensland, Brisbane, Qld. (Australia)
2007-12-15
The recent advances in numerical simulation for primary coalbed methane (CBM) recovery and enhanced coalbed-methane recovery (ECBMR) processes are reviewed, primarily focusing on the progress that has occurred since the late 1980s. Two major issues regarding the numerical modeling will be discussed in this review: first, multicomponent gas transport in in-situ bulk coal and, second, changes of coal properties during methane (CH{sub 4}) production. For the former issues, a detailed review of more recent advances in modeling gas and water transport within a coal matrix is presented. Further, various factors influencing gas diffusion through the coal matrix will be highlighted as well, such as pore structure, concentration and pressure, and water effects. An ongoing bottleneck for evaluating total mass transport rate is developing a reasonable representation of multiscale pore space that considers coal type and rank. Moreover, few efforts have been concerned with modeling water-flow behavior in the coal matrix and its effects on CH{sub 4} production and on the exchange of carbon dioxide (CO{sub 2}) and CH{sub 4}. As for the second issue, theoretical coupled fluid-flow and geomechanical models have been proposed to describe the evolution of pore structure during CH{sub 4} production, instead of traditional empirical equations. However, there is currently no effective coupled model for engineering applications. Finally, perspectives on developing suitable simulation models for CBM production and for predicting CO{sub 2}-sequestration ECBMR are suggested.
A phase screen model for simulating numerically the propagation of a laser beam in rain
Lukin, I P; Rychkov, D S; Falits, A V [Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation); Lai, Kin S; Liu, Min R [DSO National Laboratories 20 (Singapore)
2009-09-30
The method based on the generalisation of the phase screen method for a continuous random medium is proposed for simulating numerically the propagation of laser radiation in a turbulent atmosphere with precipitation. In the phase screen model for a discrete component of a heterogeneous 'air-rain droplet' medium, the amplitude screen describing the scattering of an optical field by discrete particles of the medium is replaced by an equivalent phase screen with a spectrum of the correlation function of the effective dielectric constant fluctuations that is similar to the spectrum of a discrete scattering component - water droplets in air. The 'turbulent' phase screen is constructed on the basis of the Kolmogorov model, while the 'rain' screen model utiises the exponential distribution of the number of rain drops with respect to their radii as a function of the rain intensity. Theresults of the numerical simulation are compared with the known theoretical estimates for a large-scale discrete scattering medium. (propagation of laser radiation in matter)
Claudin, Philippe
simulation of turbulent sediment transport O. Durán (1,2) , B. Andreotti (1) , P. Claudin (1) 1. Laboratoire Carolina 27515, USA Abstract Sediment transport is studied by means of two phase numerical simulations to empirical transport laws. The vertical velocities of the grains are small and sediment transport occurs
Torres-Verdín, Carlos
SPE 159250 Forecasting Gas Production in Organic Shale with the Combined Numerical Simulation algorithm to forecast gas production in organic shale that simultaneously takes into account gas diffusion-than-expected permeability in shale-gas formations, while Langmuir desorption maintains pore pressure. Simulations confirm
Mohaghegh, Shahab
1 CO2-Driven Enhanced Gas Recovery and Storage in Depleted Shale Reservoir- A Numerical Simulation for storage and enhanced gas recovery may be organic-rich shales, which CO2 is preferentially adsorbed comprehensive simulation studies to better understand CO2 injection process in shale gas reservoir. This paper
Mahesh, Krishnan
simulation of turbulent jets in crossflow Suman Muppidi and Krishnan Mahesh University of Minnesota, Minneapolis, MN, 55455, USA Direct numerical simulations are used to study a round turbulent jet in a laminar crossflow. The velocity ratio of the jet to that of the crossflow is 5.7 and the Reynolds number based
NUMERICAL SIMULATIONS OF THE EFFECTS OF CHANGING FUEL FOR TURBINES FIRED BY NATURAL GAS AND SYNGAS
Sabau, Adrian S; Wright, Ian G
2007-01-01
Gas turbines in integrated gasification combined cycle (IGCC) power plants burn a fuel gas (syngas) in which the proportions of hydrocarbons, H2, CO, water vapor, and minor impurity levels may vary significantly from those in natural gas, depending on the input feed to the gasifier and the gasification process. A data structure and computational methodology is presented for the numerical simulation of a turbine thermodynamic cycle for various fuel types, air/fuel ratios, and coolant flow rates. The approach used allowed efficient handling of turbine components and different variable constraints due to fuel changes. Examples are presented for a turbine with four stages and cooled blades. The blades were considered to be cooled in an open circuit, with air provided from appropriate compressor stages. Results are presented for the temperatures of the hot gas, alloy surface (coating-superalloy interface), and coolant, as well as for cooling flow rates. Based on the results of the numerical simulations, values were calculated for the fuel flow rates, airflow ratios, and coolant flow rates required to maintain the superalloy in the first stage blade at the desired temperature when the fuel was changed from natural gas (NG) to syngas (SG). One NG case was conducted to assess the effect of coolant pressure matching between the compressor extraction points and corresponding turbine injection points. It was found that pressure matching is a feature that must be considered for high combustion temperatures. The first series of SG simulations was conducted using the same inlet mass flow and pressure ratios as those for the NG case. The results showed that higher coolant flow rates and a larger number of cooled turbine rows were needed for the SG case. Thus, for this first case, the turbine size would be different for SG than for NG. In order to maintain the original turbine configuration (i.e., geometry, diameters, blade heights, angles, and cooling circuit characteristics) for the SG simulations, a second series of simulations was carried out by varying the inlet mass flow while keeping constant the pressure ratios and the amount of hot gas passing the first vane of the turbine. The effect of turbine matching between the NG and SG cases was approximately 10 C, and 8 to 14% for rotor inlet temperature and total cooling flows, respectively. These results indicate that turbine-compressor matching, before and after fuel change, must be included in turbine models. The last stage of the turbine, for the SG case, experienced higher inner wall temperatures than the corresponding case for NG, with the temperature of the vane approaching the maximum allowable limit. This paper was published by ASME as paper no. GT2007-27530.
Numerical simulation of gas flow through unsaturated fractured rock at Yucca Mountain, Nevada
Cooper, C.A.
1990-01-01
Numerical analysis is used to identify the physical phenomena associated with barometrically driven gas (air and water vapor) flow through unsaturated fractured rock at Yucca Mountain, Nevada. Results from simple finite difference simulations indicate that for a fractured rock scenario, the maximum velocity of air out of an uncased 10 cm borehole is 0.002 m s{sub {minus}1}. An equivalent porous medium (EPM) model was incorporated into a multiphase, multicomponent simulator to test more complex conceptual models. Results indicate that for a typical June day, a diurnal pressure wave propagates about 160 m into the surrounding Tiva Canyon hydrogeologic unit. Dry air that enters the formation evaporates water around the borehole which reduces capillary pressure. Multiphase countercurrent flow develops in the vicinity of the hole; the gas phase flows into the formation while the liquid phase flows toward the borehole. The effect occurs within 0.5 m of the borehole. The amount of water vapor leaving the formation during 1 day is 900 cm{sup 3}. This is less than 0.1% of the total recharge into the formation, suggesting that the barometric effect may be insignificant in drying the unsaturated zone. However, gas phase velocities out of the borehole (3 m s{sup {minus}1}), indicating that observed flow rates from wells along the east flank of Yucca Mountain were able to be simulated with a barometric model.
Two-scale numerical simulation of the weakly compressible 1D isentropic Euler equations
Frénod, Emmanuel
to simulate plasmas submitted to strong magnetic field. Of course, simulations of magnetic confinement fusion
Virial theorem analysis of 3D numerical simulations of MHD self-gravitating turbulence
Mohsen Shadmehri; Enrique Vazquez-Semadeni; Javier Ballesteros-Paredes
2001-11-30
We discuss the virial balance of all members of a cloud ensemble in numerical simulations of self-gravitating MHD turbulence. We first discuss the choice of reference frame for evaluating the terms entering the virial theorem (VT), concluding that the balance of each cloud should be measured in its own reference frame. We then report preliminary results suggesting that a) the clouds are far from virial equilibrium, with the ``geometric'' (time derivative) terms dominating the VT. b) The surface terms in the VT are as important as the volume ones, and tend to decrease the action of the latter. c) This implies that gravitational binding should be considered including the surface terms in the overall balance.
A direct numerical simulation method for complex modulus of particle dispersions
T. Iwashita; T. Kumagai; R. Yamamoto
2010-04-24
We report an extension of the smoothed profile method (SPM)[Y. Nakayama, K. Kim, and R. Yamamoto, Eur. Phys. J. E {\\bf 26}, 361(2008)], a direct numerical simulation method for calculating the complex modulus of the dispersion of particles, in which we introduce a temporally oscillatory external force into the system. The validity of the method was examined by evaluating the storage $G'(\\omega)$ and loss $G"(\\omega)$ moduli of a system composed of identical spherical particles dispersed in an incompressible Newtonian host fluid at volume fractions of $\\Phi=0$, 0.41, and 0.51. The moduli were evaluated at several frequencies of shear flow; the shear flow used here has a zigzag profile, as is consistent with the usual periodic boundary conditions.
Skinner, M Aaron
2015-01-01
Radiation feedback from young star clusters embedded in giant molecular clouds (GMCs) is believed to be important to the control of star formation. For the most massive and dense clouds, including those in which super star clusters (SSCs) are born, pressure from reprocessed radiation exerted on dust grains may disperse a significant portion of the cloud mass back into the interstellar medium (ISM). Using our radiaton hydrodynamics (RHD) code, Hyperion, we conduct a series of numerical simulations to test this idea. Our models follow the evolution of self-gravitating, strongly turbulent clouds in which collapsing regions are replaced by radiating sink particles representing stellar clusters. We evaluate the dependence of the star formation efficiency (SFE) on the size and mass of the cloud and $\\kappa$, the opacity of the gas to infrared (IR) radiation. We find that the single most important parameter determining the evolutionary outcome is $\\kappa$, with $\\kappa \\gtrsim 15 \\text{ cm}^2 \\text{ g}^{-1}$ needed ...
Numerical simulation of laminar plasma dynamos in a cylindrical von Karman flow
Khalzov, I. V.; Brown, B. P.; Schnack, D. D.; Forest, C. B. [University of Wisconsin, 1150 University Avenue, Madison, Wisconsin 53706 (United States); Ebrahimi, F. [University of New Hampshire, 8 College Road, Durham, New Hampshire 03824 (United States)
2011-03-15
The results of a numerical study of the magnetic dynamo effect in cylindrical von Karman plasma flow are presented with parameters relevant to the Madison Plasma Couette Experiment. This experiment is designed to investigate a broad class of phenomena in flowing plasmas. In a plasma, the magnetic Prandtl number Pm can be of order unity (i.e., the fluid Reynolds number Re is comparable to the magnetic Reynolds number Rm). This is in contrast to liquid metal experiments, where Pm is small (so, Re>>Rm) and the flows are always turbulent. We explore dynamo action through simulations using the extended magnetohydrodynamic NIMROD code for an isothermal and compressible plasma model. We also study two-fluid effects in simulations by including the Hall term in Ohm's law. We find that the counter-rotating von Karman flow results in sustained dynamo action and the self-generation of magnetic field when the magnetic Reynolds number exceeds a critical value. For the plasma parameters of the experiment, this field saturates at an amplitude corresponding to a new stable equilibrium (a laminar dynamo). We show that compressibility in the plasma results in an increase of the critical magnetic Reynolds number, while inclusion of the Hall term in Ohm's law changes the amplitude of the saturated dynamo field but not the critical value for the onset of dynamo action.
Numerical simulation of laminar plasma dynamos in a cylindrical von K\\'arm\\'an flow
Khalzov, I V; Ebrahimi, F; Schnack, D D; Forest, C B; 10.1063/1.3559472
2011-01-01
The results of a numerical study of the magnetic dynamo effect in cylindrical von K\\'arm\\'an plasma flow are presented with parameters relevant to the Madison Plasma Couette Experiment. This experiment is designed to investigate a broad class of phenomena in flowing plasmas. In a plasma, the magnetic Prandtl number Pm can be of order unity (i.e., the fluid Reynolds number Re is comparable to the magnetic Reynolds number Rm). This is in contrast to liquid metal experiments, where Pm is small (so, Re>>Rm) and the flows are always turbulent. We explore dynamo action through simulations using the extended magnetohydrodynamic NIMROD code for an isothermal and compressible plasma model.We also study two-fluid effects in simulations by including the Hall term in Ohm's law. We find that the counter-rotating von K\\'arm\\'an flow results in sustained dynamo action and the self-generation of magnetic field when the magnetic Reynolds number exceeds a critical value. For the plasma parameters of the experiment, this field ...
Numerical simulation of the compressor coil of the plasma dynamic accelerator
Thomas, P.
1997-01-01
The plasma dynamic accelerator accelerates a plasma to very high velocities in a coaxial accelerator and then compresses it in a compressor coil, achieving high densities. The axial component of the current distribution, extending from the tip of the coaxial accelerator`s center electrode to the coil turns, causes compressing forces, the radial component yields accelerating forces. The rapid change of the coil current induces azimuthal eddy currents in the plasma that interact with the coil`s magnetic field, again yielding Lorentz forces. Aerodynamic compression may also be an important effect. A new two-dimensional magnetohydrodynamics code is used to investigate which of these effects are really important for the compression. The code allows one to simulate all effects mentioned separately and in combination. In a first step only aerodynamic compression is considered. Then each electromagnetic effect is imposed on the system. Finally, a complete simulation of the compressor coil is performed. The analysis of the results provides new insights in the way the coil operates. This paper presents important aspects of the mathematical model and of the numerical implementation and reports results.
Zhao Xinghai; Mathews, Grant J.
2011-01-15
General relativistic corrections to the expansion rate of the Universe arise when the Einstein equations are averaged over a spatial volume in a locally inhomogeneous cosmology. It has been suggested that they may contribute to the observed cosmic acceleration. In this paper, we propose a new scheme that utilizes numerical simulations to make a realistic estimate of the magnitude of these corrections for general inhomogeneities in (3+1) spacetime. We then quantitatively calculate the volume averaged expansion rate using N-body large-scale structure simulations and compare it with the expansion rate in a standard FRW cosmology. We find that in the weak gravitational field limit, the converged corrections are slightly larger than the previous claimed 10{sup -5} level, but not large enough nor even of the correct sign to drive the current cosmic acceleration. Nevertheless, the question of whether the cumulative effect can significantly change the expansion history of the Universe needs to be further investigated with strong-field relativity.
Hindmarsh, Mark; Rummukainen, Kari; Weir, David J
2015-01-01
We present details of numerical simulations of the gravitational radiation produced by a first order {thermal} phase transition in the early universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow $L_\\text{f}$) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to $L_\\text{f}$ and the square of the fluid kinetic energy density. We identify a dimensionless parameter $\\tilde\\Omega_\\text{GW}$ characterising the efficiency of this "acoustic" gravitational wave production whose value is $8\\pi\\tilde\\Omega_\\text{GW} \\simeq 0.8 \\pm 0.1$ across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope appr...
Mark Hindmarsh; Stephan J. Huber; Kari Rummukainen; David J. Weir
2015-04-13
We present details of numerical simulations of the gravitational radiation produced by a first order {thermal} phase transition in the early universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow $L_\\text{f}$) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to $L_\\text{f}$ and the square of the fluid kinetic energy density. We identify a dimensionless parameter $\\tilde\\Omega_\\text{GW}$ characterising the efficiency of this "acoustic" gravitational wave production whose value is $8\\pi\\tilde\\Omega_\\text{GW} \\simeq 0.8 \\pm 0.1$ across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope approximation. Not only is the power spectrum steeper (apart from an initial transient) but the gravitational wave energy density is generically two orders of magnitude or more larger.
Numerical simulations of two-phase Taylor-Couette turbulence using an Euler-Lagrange approach
Spandan, Vamsi; Verzicco, Roberto; Lohse, Detlef
2015-01-01
Two-phase turbulent Taylor-Couette (TC) flow is simulated using an Euler-Lagrange approach to study the effects of a secondary phase dispersed into a turbulent carrier phase (here bubbles dispersed into water). The dynamics of the carrier phase is computed using Direct Numerical Simulations (DNS) in an Eulerian framework, while the bubbles are tracked in a Lagrangian manner by modelling the effective drag, lift, added mass and buoyancy force acting on them. Two-way coupling is implemented between the dispersed phase and the carrier phase which allows for momentum exchange among both phases and to study the effect of the dispersed phase on the carrier phase dynamics. The radius ratio of the TC setup is fixed to $\\eta=0.833$, and a maximum inner cylinder Reynolds number of $Re_i=8000$ is reached. We vary the Froude number ($Fr$), which is the ratio of the centripetal to the gravitational acceleration of the dispersed phase and study its effect on the net torque required to drive the TC system. In a two-phase TC...
GPU accelerated flow solver for direct numerical simulation of turbulent flows
Salvadore, Francesco [CASPUR – via dei Tizii 6/b, 00185 Rome (Italy)] [CASPUR – via dei Tizii 6/b, 00185 Rome (Italy); Bernardini, Matteo, E-mail: matteo.bernardini@uniroma1.it [Department of Mechanical and Aerospace Engineering, University of Rome ‘La Sapienza’ – via Eudossiana 18, 00184 Rome (Italy)] [Department of Mechanical and Aerospace Engineering, University of Rome ‘La Sapienza’ – via Eudossiana 18, 00184 Rome (Italy); Botti, Michela [CASPUR – via dei Tizii 6/b, 00185 Rome (Italy)] [CASPUR – via dei Tizii 6/b, 00185 Rome (Italy)
2013-02-15
Graphical processing units (GPUs), characterized by significant computing performance, are nowadays very appealing for the solution of computationally demanding tasks in a wide variety of scientific applications. However, to run on GPUs, existing codes need to be ported and optimized, a procedure which is not yet standardized and may require non trivial efforts, even to high-performance computing specialists. In the present paper we accurately describe the porting to CUDA (Compute Unified Device Architecture) of a finite-difference compressible Navier–Stokes solver, suitable for direct numerical simulation (DNS) of turbulent flows. Porting and validation processes are illustrated in detail, with emphasis on computational strategies and techniques that can be applied to overcome typical bottlenecks arising from the porting of common computational fluid dynamics solvers. We demonstrate that a careful optimization work is crucial to get the highest performance from GPU accelerators. The results show that the overall speedup of one NVIDIA Tesla S2070 GPU is approximately 22 compared with one AMD Opteron 2352 Barcelona chip and 11 compared with one Intel Xeon X5650 Westmere core. The potential of GPU devices in the simulation of unsteady three-dimensional turbulent flows is proved by performing a DNS of a spatially evolving compressible mixing layer.
Terascale Direct Numerical Simulations of Turbulent Combustion: Capabilities and Limits (PReSS Talk)
Yoo, Chun Sang
2009-03-26
The rapid growth in computational capabilities has provided great opportunities for direct numerical simulations (DNS) of turbulent combustion, a type of simulations without any turbulence model. With the help of terascale high performance supercomputing (HPC) resources, we are now able to provide fundamental insight into turbulence-chemistry interaction in simple laboratory-scale turbulent flames with detailed chemistry using three-dimensional (3D) DNS. However, the actual domain size of 3D-DNS is still limited within {approx} O(10 cm{sup 3}) due to its tremendously high grid resolution required to resolve the smallest turbulent length scale as well as flame structures. Moreover, 3D-DNS will require more computing powers to investigate next-generation engines, of which operating conditions will be characterized by higher pressures, lower temperatures, and higher levels of dilution. In this talk, I will discuss the capabilities and limits of DNS of turbulent combustion and present some results of ignition/extinction characteristics of a highly diluted hydrogen flame counter-flowing against heated air. The results of our recent 3D-DNS of a spatially-developing turbulent lifted hydrogen jet flame in heated coflow will also be presented. The 3D-DNS was performed at a jet Reynolds number of 11,000 with {approx} 1 billion grid points, which required 3.5 million CPU hours on Cray XT3/XT4 at Oak Ridge National Laboratories.
Yang, Xiaofan; Scheibe, Timothy D.; Richmond, Marshall C.; Perkins, William A.; Vogt, Sarah J.; Codd, Sarah L.; Seymour, Joseph D.; Mckinley, Matthew I.
2013-04-01
A significant body of current research is aimed at developing methods for numerical simulation of flow and transport in porous media that explicitly resolve complex pore and solid geometries, and at utilizing such models to study the relationships between fundamental pore-scale processes and macroscopic manifestations at larger (i.e., Darcy) scales. A number of different numerical methods for pore-scale simulation have been developed, and have been extensively tested and validated for simplified geometries. However, validation of pore-scale simulations of fluid velocity for complex, three-dimensional (3D) pore geometries that are representative of natural porous media is challenging due to our limited ability to measure pore-scale velocity in such systems. Recent advances in magnetic resonance imaging (MRI) offer the opportunity to measure not only the pore geometry, but also local fluid velocities under steady-state flow conditions in 3D and with high spatial resolution. In this paper, we present a 3D velocity field measured at sub-pore resolution (tens of micrometers) over a centimeter-scale 3D domain using MRI methods. We have utilized the measured pore geometry to perform 3D simulations of Navier-Stokes flow over the same domain using direct numerical simulation techniques. We present a comparison of the numerical simulation results with the measured velocity field. It is shown that the numerical results match the observed velocity patterns well overall except for a variance and small systematic scaling which can be attributed to the known experimental error in the MRI measurements. The comparisons presented here provide strong validation of the pore-scale simulation methods and new insights for interpretation of uncertainty in MRI measurements of pore-scale velocity. This study also provides a potential benchmark for future comparison of other pore-scale simulation methods.
TOUGH2: A general-purpose numerical simulator for multiphase nonisothermal flows
Pruess, K. [Lawrence Berkeley Lab., CA (United States)
1991-06-01
Numerical simulators for multiphase fluid and heat flows in permeable media have been under development at Lawrence Berkeley Laboratory for more than 10 yr. Real geofluids contain noncondensible gases and dissolved solids in addition to water, and the desire to model such `compositional` systems led to the development of a flexible multicomponent, multiphase simulation architecture known as MULKOM. The design of MULKOM was based on the recognition that the mass-and energy-balance equations for multiphase fluid and heat flows in multicomponent systems have the same mathematical form, regardless of the number and nature of fluid components and phases present. Application of MULKOM to different fluid mixtures, such as water and air, or water, oil, and gas, is possible by means of appropriate `equation-of-state` (EOS) modules, which provide all thermophysical and transport parameters of the fluid mixture and the permeable medium as a function of a suitable set of primary thermodynamic variables. Investigations of thermal and hydrologic effects from emplacement of heat-generating nuclear wastes into partially water-saturated formations prompted the development and release of a specialized version of MULKOM for nonisothermal flow of water and air, named TOUGH. TOUGH is an acronym for `transport of unsaturated groundwater and heat` and is also an allusion to the tuff formations at Yucca Mountain, Nevada. The TOUGH2 code is intended to supersede TOUGH. It offers all the capabilities of TOUGH and includes a considerably more general subset of MULKOM modules with added capabilities. The paper briefly describes the simulation methodology and user features.
Numerical relativity simulations of thick accretion disks around tilted Kerr black holes
Vassilios Mewes; José A. Font; Filippo Galeazzi; Pedro J. Montero; Nikolaos Stergioulas
2015-06-12
In this work we present 3D numerical relativity simulations of thick accretion disks around {\\it tilted} Kerr black holes. We investigate the evolution of three different initial disk models with a range of initial black hole spin magnitudes and tilt angles. For all the disk-to-black hole mass ratios considered ($0.044-0.16$) we observe significant black hole precession and nutation during the evolution. This indicates that for such mass ratios, neglecting the self-gravity of the disks by evolving them in a fixed background black hole spacetime is not justified. We find that the two more massive models are unstable against the Papaloizou-Pringle (PP) instability and that those PP-unstable models remain unstable for all initial spins and tilt angles considered, showing that the development of the instability is a very robust feature of such PP-unstable disks. The tilt between the black hole spin and the disk is strongly modulated during the growth of the PP instability, causing a partial global realignment of black hole spin and disk angular momentum in the most massive model with constant specific angular momentum $l$. For the model with non-constant $l$-profile we observe a long-lived $m=1$ non-axisymmetric structure which shows strong oscillations of the tilt angle in the inner regions of the disk. We attribute this effect to the development of Kozai-Lidov oscillations. Our simulations also confirm earlier findings that the development of the PP instability causes the long-term emission of large amplitude gravitational waves, predominantly for the $l=m=2$ multipole mode. The imprint of the BH precession on the gravitational waves from tilted BH-torus systems remains an interesting open issue that would require significantly longer simulations than those presented in this work.
Jha, Pallavi; Kumar Verma, Nirmal [Department of Physics, University of Lucknow, Lucknow-226007 (India)
2014-06-15
A one-dimensional numerical model for studying terahertz radiation generation by intense laser pulses propagating, in the extraordinary mode, through magnetized plasma has been presented. The direction of the static external magnetic field is perpendicular to the polarization as well as propagation direction of the laser pulse. A transverse electromagnetic wave with frequency in the terahertz range is generated due to the presence of the magnetic field. Further, two-dimensional simulations using XOOPIC code show that the THz fields generated in plasma are transmitted into vacuum. The fields obtained via simulation study are found to be compatible with those obtained from the numerical model.
Olshanskii, Maxim A.
and accurate numerical methods for computing flows with free surfaces and interfaces, see, e.g., [1, 2 is studied in a series of numerical experiments. Institute of Numerical Mathematics, Russian Academy@math.uh.edu Department of Energy Resources Engineering, Stanford University and Institute of Numerical Mathematics
Kirby, James T.
Numerical Simulation of the 2011 Tohoku Tsunami Based on a New Transient FEM Co-seismic Source Abstract--In this work, we simulate the 2011 M9 Tohoku-Oki tsunami using new coseismic tsunami sources com- pare observations and numerical simulations of the tsunami's far- and near-field coastal impact
Zhang, Meng
2008-10-10
SIMULATIONS OF JET-FRONT GRAVITY WAVES OVER NORTH AMERICA AND NORTH ATLANTIC OCEAN A Thesis by MENG ZHANG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 2008 Major Subject: Atmospheric Sciences SATELLITE OBSERVATIONS AND NUMERICAL SIMULATIONS OF JET-FRONT GRAVITY WAVES OVER NORTH AMERICA AND NORTH ATLANTIC OCEAN A Thesis by MENG ZHANG Submitted to the Office...
Numerical simulations of quiet sun magnetism: On the contribution from a small-scale dynamo
Rempel, M.
2014-07-10
We present a series of radiative MHD simulations addressing the origin and distribution of the mixed polarity magnetic field in the solar photosphere. To this end, we consider numerical simulations that cover the uppermost 2-6 Mm of the solar convection zone and we explore scales ranging from 2 km to 25 Mm. We study how the strength and distribution of the magnetic field in the photosphere and subsurface layers depend on resolution, domain size, and boundary conditions. We find that 50% of the magnetic energy at the ? = 1 level comes from fields with the less than 500 G strength and that 50% of the energy resides on scales smaller than about 100 km. While the probability distribution functions are essentially independent of resolution, properly describing the spectral energy distribution requires grid spacings of 8 km or smaller. The formation of flux concentrations in the photosphere exceeding 1 kG requires a mean vertical field strength greater than 30-40 G at ? = 1. The filling factor of kG flux concentrations increases with overall domain size as the magnetic field becomes organized by larger, longer-lived flow structures. A solution with a mean vertical field strength of around 85 G at ? = 1 requires a subsurface rms field strength increasing with depth at the same rate as the equipartition field strength. We consider this an upper limit for the quiet Sun field strength, which implies that most of the convection zone is magnetized close to the equipartition. We discuss these findings in view of recent high-resolution spectropolarimetric observations of quiet Sun magnetism.
Physical mechanism and numerical simulation of the inception of the lightning upward leader
Li Qingmin [Beijing Key Lab of High Voltage and EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing 102206 (China) and State Key Lab of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Lu Xinchang; Shi Wei; Zhang Li; Zou Liang; Lou Jie [Shandong Provincial Key Lab of UHV Technology and Gas Discharge, School of Electrical Engineering, Shandong University, Jinan 250061 (China)
2012-12-15
The upward leader is a key physical process of the leader progression model of lightning shielding. The inception mechanism and criterion of the upward leader need further understanding and clarification. Based on leader discharge theory, this paper proposes the critical electric field intensity of the stable upward leader (CEFISUL) and characterizes it by the valve electric field intensity on the conductor surface, E{sub L}, which is the basis of a new inception criterion for the upward leader. Through numerical simulation under various physical conditions, we verified that E{sub L} is mainly related to the conductor radius, and data fitting yields the mathematical expression of E{sub L}. We further establish a computational model for lightning shielding performance of the transmission lines based on the proposed CEFISUL criterion, which reproduces the shielding failure rate of typical UHV transmission lines. The model-based calculation results agree well with the statistical data from on-site operations, which show the effectiveness and validity of the CEFISUL criterion.
A numerical simulation of solar energetic particle dropouts during impulsive events
Wang, Y.; Qin, G. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, M. [Department of Physics and Space Science, Florida Institute of Technology, Melbourne, FL 32901 (United States); Dalla, S., E-mail: ywang@spaceweather.ac.cn, E-mail: gqin@spaceweather.ac.cn [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire PR1 2HE (United Kingdom)
2014-07-10
This paper investigates the conditions for producing rapid variations of solar energetic particle (SEP) intensity commonly known as 'dropouts'. In particular, we use numerical model simulations based on solving the focused transport equation in the three-dimensional Parker interplanetary magnetic field to put constraints on the properties of particle transport coefficients in both directions perpendicular and parallel to the magnetic field. Our calculations of the temporal intensity profile of 0.5 and 5 MeV protons at the Earth show that the perpendicular diffusion must be small while the parallel mean free path is long in order to reproduce the phenomenon of SEP dropouts. When the parallel mean free path is a fraction of 1 AU and the observer is located at 1 AU, the perpendicular to parallel diffusion ratio must be below 10{sup –5} if we want to see the particle flux dropping by at least several times within 3 hr. When the observer is located at a larger solar radial distance, the perpendicular to parallel diffusion ratio for reproducing the dropouts should be even lower than that in the case of 1 AU distance. A shorter parallel mean free path or a larger radial distance from the source to observer will cause the particles to arrive later, making the effects of perpendicular diffusion more prominent and SEP dropouts disappear. All of these effects require the magnetic turbulence that resonates with the particles to be low everywhere in the inner heliosphere.
Evaluation and Numerical Simulation of Tsunami for Coastal Nuclear Power Plants of India
Sharma, Pavan K.; Singh, R.K.; Ghosh, A.K.; Kushwaha, H.S. [Bhabha Atomic Research Centre-Trombay, Mumbai 400 085 (India)
2006-07-01
Recent tsunami generated on December 26, 2004 due to Sumatra earthquake of magnitude 9.3 resulted in inundation at the various coastal sites of India. The site selection and design of Indian nuclear power plants demand the evaluation of run up and the structural barriers for the coastal plants: Besides it is also desirable to evaluate the early warning system for tsunami-genic earthquakes. The tsunamis originate from submarine faults, underwater volcanic activities, sub-aerial landslides impinging on the sea and submarine landslides. In case of a submarine earthquake-induced tsunami the wave is generated in the fluid domain due to displacement of the seabed. There are three phases of tsunami: generation, propagation, and run-up. Reactor Safety Division (RSD) of Bhabha Atomic Research Centre (BARC), Trombay has initiated computational simulation for all the three phases of tsunami source generation, its propagation and finally run up evaluation for the protection of public life, property and various industrial infrastructures located on the coastal regions of India. These studies could be effectively utilized for design and implementation of early warning system for coastal region of the country apart from catering to the needs of Indian nuclear installations. This paper presents some results of tsunami waves based on different analytical/numerical approaches with shallow water wave theory. (authors)
Bu, De-Fu; Gan, Zhao-Ming; Yang, Xiao-hong
2015-01-01
In previous works, it has been shown that strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole thus it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem based on hydrodynamical numerical simulations. For this aim, we have taken into account the gravity of both the central black hole and the nuclear star clusters. When calculating the latter, we assume that the velocity dispersion of stars is a constant and the gravitational potential of the nuclear star cluster $\\propto \\sigma^2 \\ln (r)$, where $\\sigma$ is the velocity dispersion of stars and $r$ is the distance from the center of the galaxy. Different from previous works, we focus on the region where the gravitational potential is dominated by the star cluster. We find that, same as the accretion flow at small radii, the mass inflow rate decreases inward and the flow is convectively unstable. However, trajectory analysis has sh...
Numerical Simulations of the Island-Induced Circulations over the Island of Hawaii during HaRP
Chen, Yi-Leng
Numerical Simulations of the Island-Induced Circulations over the Island of Hawaii during HaRP YANG YANG AND YI-LENG CHEN Department of Meteorology, SOEST, University of Hawaii at Manoa, Honolulu, Hawaii island-scale circulations over the island of Hawaii during the Hawaiian Rainband Project (HaRP, 11 July
Xie, Shang-Ping
The Thermal Wake of Kauai Island: Satellite Observations and Numerical Simulations* YANG YANG, SHANG-PING XIE, AND JAN HAFNER International Pacific Research Center, SOEST, University of Hawaii at Manoa, Honolulu, Hawaii (Manuscript received 12 February 2007, in final form 12 December 2007) ABSTRACT
Bell, John B.
Multidimensional Numerical Simulation of a Pulse Combustor \\Lambda Daniel L. Marcus, Richard B Abstract We have developed a new threedimensional modeling capability to study the behavior of pulsedimensional, reacting fluid dynamics in the combustion chamber and in corporates lowerdimensional approximations
Torres-Verdín, Carlos
Numerical simulation of dual-laterolog measurements in the presence of dipping, anisotropic Modern hydrocarbon development techniques make extensive use of highly deviated and horizontal wells-laterolog measurements acquired in 3D logging environments to appraise the reliability of measurement and interpretation
Komatitsch, Dimitri
derivatives or analytical expressions to compute the rotational Green's tensor. We validate the method using Numerical Simulation of Ground Rotations along 2D Topographical Profiles under the Incidence-Sesma, R. Madec, and D. Komatitsch Abstract The surface displacement field along a topographical profile
Boyer, Edmond
Introduction Flattening the Earth Continuation procedure Flat Earth Numerical simulations Continuation from a flat to a round Earth model in the coplanar orbit transfer problem M. Cerf1, T. Haberkorn, SADCO 2011, March 2nd M. Cerf, T. Haberkorn, E. Tr´elat Continuation from a flat to a round Earth model
Kirby, James T.
for the purpose of a tsunami warning system. In this context we describe the Thailand case study of the 26th, warning system, Thailand case study Introduction Any fast deformation of the ocean sea floor may, in some2 Keynote 2 How Numerical Simulations May Contribute to Tsunami Risk Preparedness: The 26 December
Aktinol, Eduardo
2014-01-01
Numerical Simulation of Pool Boiling: A Review. ” Journal ofBooth, W. (2012). “Nucleate Pool Boiling Experiments (NPBX)and Booth, W. , “ ,Nucleate Pool Boiling Experiments (NPBX)
Celani, F; Tripodi, P; Petrocchi, A; Nakamura, M; Di Gioacchino, D; Marini, P; Di Stefano, V; Preparata, Giuliano; Verpelli, M
1995-01-01
Numerical simulation of deuterium loading profile in palladium and palladium alloy plates from experimental data of absorbed mole rate obtained using $\\mu$s pulsed electrolysis
Test of some numerical limiters for the conservative PSM scheme for 4D Drift-Kinetic simulations
Jerome Guterl; Jean-Philippe Braeunig; Nicolas Crouseilles; Virginie Grandgirard; Guillaume Latu; Michel Mehrenberger; Eric Sonnendrücker
2010-12-13
The purpose of this work is simulation of magnetised plasmas in the ITER project framework. In this context, Vlasov-Poisson like models are used to simulate core turbulence in the tokamak in a toroidal geometry. This leads to heavy simulation because a 6D dimensional problem has to be solved, 3D in space and 3D in velocity. The model is reduced to a 5D gyrokinetic model, taking advantage of the particular motion of particles due to the presence of a strong magnetic field. However, accurate schemes, parallel algorithms need to be designed to bear these simulations. This paper describes a Hermite formulation of the conservative PSM scheme which is very generic and allows to implement different semi-Lagrangian schemes. We also test and propose numerical limiters which should improve the robustness of the simulations by diminishing spurious oscillations. We only consider here the 4D drift-kinetic model which is the backbone of the 5D gyrokinetic models and relevant to build a robust and accurate numerical method.
Test of some numerical limiters for the conservative PSM scheme for 4D Drift-Kinetic simulations
Guterl, Jerome; Crouseilles, Nicolas; Grandgirard, Virginie; Latu, Guillaume; Mehrenberger, Michel; Sonnendrücker, Eric
2010-01-01
The purpose of this work is simulation of magnetised plasmas in the ITER project framework. In this context, Vlasov-Poisson like models are used to simulate core turbulence in the tokamak in a toroidal geometry. This leads to heavy simulation because a 6D dimensional problem has to be solved, 3D in space and 3D in velocity. The model is reduced to a 5D gyrokinetic model, taking advantage of the particular motion of particles due to the presence of a strong magnetic field. However, accurate schemes, parallel algorithms need to be designed to bear these simulations. This paper describes a Hermite formulation of the conservative PSM scheme which is very generic and allows to implement different semi-Lagrangian schemes. We also test and propose numerical limiters which should improve the robustness of the simulations by diminishing spurious oscillations. We only consider here the 4D drift-kinetic model which is the backbone of the 5D gyrokinetic models and relevant to build a robust and accurate numerical method.
Garain, Sudip K; Chakrabarti, Sandip K
2013-01-01
We study the spectral and timing properties of a two component advective flow (TCAF) around a black hole by numerical simulation. Several cases have been simulated by varying the Keplerian disk rate and the resulting spectra and lightcurves have been produced for all the cases. The dependence of the spectral states and quasi-periodic oscillation (QPO) frequencies on the flow parameters is discussed. We also find the earlier explanation of arising of QPOs as the resonance between infall time scale and cooling time scale remain valid even for Compton cooling.
Nikoleris, Teo
1988-01-01
NUMERICAL SIMULATION OF THE NON-ISOTHERMAL DEVELOPING FLOXV OF A NONLINEAR VISCOELASTIC FLUID IN A RECTANGULAR CHANNEL A Thesis by TEO NIKOLERIS Submitted to the Graduate College of Texas A&M University in partial fulfillment... developing flow of a nonlinear viscoelas- tic fluid. The temperature dependence of the rheological parameters was imposed using an Arrhenius-like exponential relationship. The flow was creeping, at the early stages of thermal development and wall cooling...
Saleh, Habeeb H.
1990-01-01
Structure Alignment CHAPTER III DESCRIPTION OF THE EXPERIMENTAL FACILITY III. I Description of FFTF The Fast Flux Test Facility (FFTF) is a 400-MWt, sodium-cooled, low-pressure, high-temperarure, fast neutron flux, nuclear fission reactor plant...NUMERICAL SIMULATION OF INTERMEDIATE HEAT EXCHANGER OF THE LIQUID METAL FAST BREEDER REACTOR USING COMMIX-1B A Thesis by HABEEB H. SALEH Submitted to the Office of Graduate Studies of Texas A@M University in partial fulfillment...
Pham, Van Sang
We present a systematic, multiscale, fully detailed numerical modeling for dynamics of fluid flow and ion transport covering Ohmic, limiting, and overlimiting current regimes in conductance of ion-selective membrane. By ...
Three-dimensional numerical manifold method simulations for blocky rock analysis
Shentu, Longfei
2011-01-01
After decades of development, people realize that there are wider and more various applications of numerical modeling and analysis. However, current feasible software tools cannot satisfy engineering and commercial goals. ...
t -software package for numerical simulations of radioactive contaminant transport in groundwater
Frolkovic, Peter
in groundwater Peter Frolkovic Michael Lampe Gabriel Wittum September 16, 2005 Abstract The software package r3t or as numerical solution of some groundwater flow model, e.g., the density driven flow problem. The matrix Di = Di
On the numerical simulation of the instationary free fall of a solid in a fluid.
from meteorology, sedimentology and aerospace engineering to biology. We present a new numerical method], sedimentology [1], aerospace engineering [21] and biology (e.g. models for animal flights [2]). Recently
Not Available
2012-02-01
New code will help accelerate design improvements by providing a high-fidelity simulation tool to study power performance, structural loading, and the interactions between devices in arrays.
Direct numerical simulations of type Ia supernovae flames II: The rayleigh-taylor instability
Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.
2004-01-01
Weaver, T. A. 1994, in Supernovae, Les Houches, Session LIV,Simulations of Type Ia Supernovae Flames II: The Rayleigh-Subject headings: supernovae: general — white dwarfs —
Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability
Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.
2003-01-01
Simulations of Type Ia Supernovae Flames I: The Landau-Subject headings: supernovae: general — white dwarfs —could occur in Type Ia supernovae (Niemeyer & Woosley 1997),
Godfrey, Brendan B.
2014-01-01
relativistic plasma drift in EM-PIC code, American Institutebeam multidimensional PIC simulations employing theusing the Particle-In-Cell (PIC) technique in the laboratory
Hindi, Haitham; Prabhakar, Shyam; Fox, John D.; Linscott, Ivan; Teytelman, Dmitri; /SLAC
2011-08-31
We present a technique for the design and verification of efficient bunch-by-bunch controllers for damping longitudinal multibunch instabilities. The controllers attempt to optimize the use of available feedback amplifier power - one of the most expensive components of a feedback system - and define the limits of the closed loop system performance. Our design technique alternates between analytic computation of single bunch optimal controllers and verification on a multibunch numerical simulator. The simulator uses PEP-II parameters and identifies unstable coupled bunch modes, their growth rates and their damping rates with feedback. The results from the simulator are shown to be in reasonable agreement with analytical calculations based on the single bunch model. The technique is then used to evaluate the performance of a variety of controllers proposed for PEP-II.
Modeling Computer Viruses MSc Thesis (Afstudeerscriptie)
Amsterdam, University of
Modeling Computer Viruses MSc Thesis (Afstudeerscriptie) written by Luite Menno Pieter van Zelst About half a year ago, Alban Ponse, my thesis supervisor, suggested that the topic of `computer viruses indus- try and the creators of computer viruses. After all, the anti-virus industry stands to lose a lot
:,; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ain, A; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corpuz, A; Corsi, A; Costa, C A; Coughlin, M W; Coughlin, S; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Donath, A; Donovan, F; Dooley, K L; Doravari, S; Dossa, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H; Ehrens, P; Eichholz, J; Eikenberry, S S; Endr?czi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, C; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gushwa, K; Gustafson, E K; Gustafson, R; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Hooper, S; Hopkins, P; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N; Kim, N G; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I
2014-01-01
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave astrophysics communities. The purpose of NINJA is to study the ability to detect gravitational waves emitted from merging binary black holes and recover their parameters with next-generation gravitational-wave observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete binary black hole hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a "blind injection challenge" similar to that conducted in recent LIGO and Virgo science runs, we added 7 hybrid waveforms to two months of data recolored to predictions of Advanced LIGO and Advanced Virgo sensitivity curves during their first observing runs. The resulting data was analyzed by gravitational-wave detection algorithms and 6 of the waveforms were recovered w...
3D-radiation hydro simulations of disk-planet interactions: I. Numerical algorithm and test cases
H. Klahr; W. Kley
2005-10-13
We study the evolution of an embedded protoplanet in a circumstellar disk using the 3D-Radiation Hydro code TRAMP, and treat the thermodynamics of the gas properly in three dimensions. The primary interest of this work lies in the demonstration and testing of the numerical method. We show how far numerical parameters can influence the simulations of gap opening. We study a standard reference model under various numerical approximations. Then we compare the commonly used locally isothermal approximation to the radiation hydro simulation using an equation for the internal energy. Models with different treatments of the mass accretion process are compared. Often mass accumulates in the Roche lobe of the planet creating a hydrostatic atmosphere around the planet. The gravitational torques induced by the spiral pattern of the disk onto the planet are not strongly affected in the average magnitude, but the short time scale fluctuations are stronger in the radiation hydro models. An interesting result of this work lies in the analysis of the temperature structure around the planet. The most striking effect of treating the thermodynamics properly is the formation of a hot pressure--supported bubble around the planet with a pressure scale height of H/R ~ 0.5 rather than a thin Keplerian circumplanetary accretion disk. We also observe an outflow of gas above and below the planet during the gap opening phase.
Modeling and numerical techniques for high-speed digital simulation of nuclear power plants
Wulff, W.; Cheng, H.S.; Mallen, A.N.
1987-01-01
Conventional computing methods are contrasted with newly developed high-speed and low-cost computing techniques for simulating normal and accidental transients in nuclear power plants. Six principles are formulated for cost-effective high-fidelity simulation with emphasis on modeling of transient two-phase flow coolant dynamics in nuclear reactors. Available computing architectures are characterized. It is shown that the combination of the newly developed modeling and computing principles with the use of existing special-purpose peripheral processors is capable of achieving low-cost and high-speed simulation with high-fidelity and outstanding user convenience, suitable for detailed reactor plant response analyses.
Meador, Charles Michael
2011-02-22
Improvements to gas turbine efficiency depend closely on cooling technologies, as efficiency increases with turbine inlet temperature. To aid in this process, simulations that consider real engine conditions need to be ...
Numerical Simulation of Land Subsidence in the Los Banos-Kettleman City Area, California
Larson, Keith J; Basagaoglu, Hakan; Marino, Miguel
2001-01-01
risk assessment of land subsidence in Shanhai. EnvironmentelObserved and simulated land subsidence for extenso meter 1 .and Miller, R. E. 1975. land subsidence due to ground water
Abd. Rahim, Mohd. Razi
2010-08-26
This doctoral project dissertation deals with the investigation of simulation/analysis in the product development process of specialized heavy ground vehicle engineering which posts some of the most challenging engineering ...
COMPARING TWO NUMERICAL MODELS IN SIMULATING HYDRODYNAMICS AND SEDIMENT TRANSPORT AT A DUAL
US Army Corps of Engineers
The overall wave energy along this coast is mild with average breaker heights estimated to be 0.25-0.30 m with Delft University of Technology (Lesser et al. 2004) and has been applied to simulate coastal systems
An adaptive framework for high-order, mixed-element numerical simulations
Caplan, Philip Claude Delhaye
2014-01-01
This work builds upon an adaptive simulation framework to allow for mixed-element meshes in two dimensions. Contributions are focused in the area of mesh generation which employs the Lk norm to produce various mesh types. ...
deYoung, Brad
, 1980). In some subpolar glacial fjords, however, the glacial ice melting can be masked by the muchCirculation induced by subglacial discharge in glacial fjords: Results from idealized numerical). The connection between ice and ocean boundaries in Arctic environments can be through glacial fjords
of the corresponding acoustic wave equation. 1. Introduction For the typical dimensions of microfluidic structures and small 1 mm particles can be understood in terms of the acoustic eigenmodes or standing ultra-sound wavesAcoustic resonances in microfluidic chips: full-image micro-PIV experiments and numerical
Melnik, Roderick
2003-01-01
and accounting for the coupling of the solids to surrounding fluid/gas media has been analysed numerically with piezoceramic shells widely used in transducer applications, ultrasonic SAW devices and flow-meters, biomedical engineering applications and smart materials and structures technology [5,6,14,15]. Such advanced applications
Robust Numerical Simulation of Porosity Evolution in Chemical Vapor Infiltration III: Three Space
Jin, Shi
is an important technol- ogy to fabricate ceramic matrix composites (CMC's). In this paper, a three) is an important and widely used tech- nology for fabricating fiber reinforced ceramic matrix composite (CMC's). Numerous types of composites can be fabricated by the CVI [1][2]. In the CVI process of fabricating
Numerical simulations of large deformation of thin shell structures using meshfree methods
Li, Shaofan
, sheet metal forming, crash-worthiness test, civil structure design, pressure vessel liability avoiding ill-conditioning as well as stiffening in numerical computations. The main advantage of such 3-D engineering signi®cance as well as technical dif®culties can be best measured by the seemingly ever
Numerical simulation of transient, incongruent vaporization induced by high power laser
Tsai, C.H.
1981-01-01
A mathematical model and numerical calculations were developed to solve the heat and mass transfer problems specifically for uranum oxide subject to laser irradiation. It can easily be modified for other heat sources or/and other materials. In the uranium-oxygen system, oxygen is the preferentially vaporizing component, and as a result of the finite mobility of oxygen in the solid, an oxygen deficiency is set up near the surface. Because of the bivariant behavior of uranium oxide, the heat transfer problem and the oxygen diffusion problem are coupled and a numerical method of simultaneously solving the two boundary value problems is studied. The temperature dependence of the thermal properties and oxygen diffusivity, as well as the highly ablative effect on the surface, leads to considerable non-linearities in both the governing differential equations and the boundary conditions. Based on the earlier work done in this laboratory by Olstad and Olander on Iron and on Zirconium hydride, the generality of the problem is expanded and the efficiency of the numerical scheme is improved. The finite difference method, along with some advanced numerical techniques, is found to be an efficient way to solve this problem.
Martin, V.; Egido, J.L.; Khoo, T.L.; Lauritsen, T.
1993-11-11
The electromagnetic decay of the nuclei {sup 152-154-156}Dy is analyzed using microscopic Hartree-Fock calculations at finite temperature. The theoretical collective transition probabilities are implemented in numerical simulations to produce theoretical espectra. Thermal shape fluctuations are also taken into account. The inclusion of these correlation is crucial in order to understand the main features of the collective E2 spectra of these isotopes at different energies. The theoretical calculations suggest a shape change as responsible for the unusual features of the spectrum of the nucleus {sup 154}Dy at high energy.
Particle velocity based universal algorithm for numerical simulation of hydraulic fractures
Wrobel, Michal
2014-01-01
In the paper, we propose a new effective mathematical formulation and resulting universal numerical algorithm capable of tackling various HF models in the framework of a unified approach. The presented numerical scheme is not limited to any particular elasticity model or crack propagation regime. Its basic assumptions are: i) proper choice of independent and dependent variables (with the direct utilization of a new one - the reduced particle velocity), ii) tracing the fracture front by use of the speed equation which can be integrated in a closed form and sets an explicit relation between the crack propagation speed and the coefficients in the asymptotic expansion of the crack opening, iii) proper regularization techniques, iv) improved temporal approximation, v) modular algorithm architecture. The application of the new dependent variable, the reduced particle velocity, instead of the usual fluid flow rate, facilitates the computation of the crack propagation speed from the local relation based on the speed ...
Use of a speed equation for numerical simulation of hydraulic fractures
Linkov, Alexander M
2011-01-01
The paper treats the propagation of a hydraulically driven crack. We explicitly write the local speed equation, which facilitates using the theory of propagating interfaces. It is shown that when neglecting the lag between the liquid front and the crack tip, the lubrication PDE yields that a solution satisfies the speed equation identically. This implies that for zero or small lag, the boundary value problem appears ill-posed when solved numerically. We suggest e - regularization, which consists in employing the speed equation together with a prescribed BC on the front to obtain a new BC formulated at a small distance behind the front rather than on the front itself. It is shown that - regularization provides accurate and stable results with reasonable time expense. It is also shown that the speed equation gives a key to proper choice of unknown functions when solving a hydraulic fracture problem numerically.
Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Isvoranu, Dragos D.; Cizmas, Paul G. A.
2003-01-01
This article presents the development of a numerical algorithm for the computation of flow and combustion in a turbine combustor. The flow and combustion are modeled by the Reynolds-averaged Navier-Stokes equations coupled with the species-conservation equations. The chemistry model used herein is a two-step, global, finite-rate combustion model for methane and combustion gases. The governing equations are written in the strong conservation form and solved using a fully implicit, finite-difference approximation. The gas dynamics and chemistry equations are fully decoupled. A correction technique has been developed to enforce the conservation of mass fractions. The numerical algorithm developed herein has beenmore »used to investigate the flow and combustion in a one-stage turbine combustor.« less
Numerical simulation: Toward the design of high-efficiency planar perovskite solar cells
Liu, Feng; Zhu, Jun E-mail: sydai@ipp.ac.cn; Wei, Junfeng; Li, Yi; Lv, Mei; Yang, Shangfeng; Zhang, Bing; Yao, Jianxi; Dai, Songyuan E-mail: sydai@ipp.ac.cn
2014-06-23
Organo-metal halide perovskite solar cells based on planar architecture have been reported to achieve remarkably high power conversion efficiency (PCE, >16%), rendering them highly competitive to the conventional silicon based solar cells. A thorough understanding of the role of each component in solar cells and their effects as a whole is still required for further improvement in PCE. In this work, the planar heterojunction-based perovskite solar cells were simulated with the program AMPS (analysis of microelectronic and photonic structures)-1D. Simulation results revealed a great dependence of PCE on the thickness and defect density of the perovskite layer. Meanwhile, parameters including the work function of the back contact as well as the hole mobility and acceptor density in hole transport materials were identified to significantly influence the performance of the device. Strikingly, an efficiency over 20% was obtained under the moderate simulation conditions.
Shlapakovski, Anatoli; Beilin, Leonid; Bliokh, Yuri; Donskoy, Moshe; Krasik, Yakov E. [Physics Department, Technion, Haifa 32000 (Israel); Hadas, Yoav [Department of Applied Physics, Rafael, PO Box 2250, Haifa 31021 (Israel); Schamiloglu, Edl [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
2014-05-07
Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated.
Kajimura, Y. [Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Japan Science and Technology Agency (JST), CREST 4-1-8 Hon-chou, Kawaguchi, Saitama 332-0012 (Japan); Matsuda, N.; Hayashida, K.; Maeno, A.; Nakashima, H. [Department of Advanced Energy Engineering Science, Interdisciplinary Graduate school of Engineering Sciences, Kyushu University, Kasugakouen 6-1, Kasuga, Fukuoka 816-580 (Japan)
2008-12-31
Numerical simulations of plasma behavior in a magnetic nozzle of a Laser-Plasma Driven Nuclear Electric Propulsion System are conducted. The propellant is heated and accelerated by the laser and expanded isotropically. The magnetic nozzle is a combination of solenoidal coils and used to collimate and guide the plasma to produce thrust. Simulation calculations by a three-dimensional hybrid code are conducted to examine the plasma behaviors in the nozzle and to estimate the thrust efficiency. We also estimate a fraction ({alpha}) of plasma particles leaking in the forward (spacecraft) direction. By a combination of a few coils, we could decrease {alpha} value without degrading the thrust efficiency. Finally, the shaped propellant is proposed to increase the thrust efficiency.
Molenkamp, C.R.; Grossman, A.
1999-12-20
A network of small balloon-borne transponders which gather very high resolution wind and temperature data for use by modern numerical weather predication models has been proposed to improve the reliability of long-range weather forecasts. The global distribution of an array of such transponders is simulated using LLNL's atmospheric parcel transport model (GRANTOUR) with winds supplied by two different general circulation models. An initial study used winds from CCM3 with a horizontal resolution of about 3 degrees in latitude and longitude, and a second study used winds from NOGAPS with a 0.75 degree horizontal resolution. Results from both simulations show that reasonable global coverage can be attained by releasing balloons from an appropriate set of launch sites.
Soker, N.; Sarazin, C.L.; O'Dea, C.P.
1988-04-01
Three-dimensional numerical hydrodynamic simulations are used to study the bending of radio jets. The simulations are compared with observations of jets in narrow-angle-tail radio sources. Two mechanisms for the observed bending are considered: direct bending of quasi-continuous jets by ram pressure from intergalactic gas and bending by pressure gradients in the interstellar gas of the host galaxy, the pressure gradients themselves being the result of ram pressure by intergalactic gas. It is shown that the pressure gradients are much less effective in bending jets, implying that the jets have roughly 30 times lower momentum fluxes if they are bent by this mechanism. Ram-pressure bending produces jets with kidney-shaped cross sections; when observed from the side, these jets appear to have diffuse extensions on the downstream side. On the other hand, pressure-gradient bending causes the jets to be densest near their upstream side. 31 references.
Numerical simulation of the photoisomerization of retinal from the cis to the trans form
Sinha, Indrani
2009-05-15
systems including ethylene, 2-butene, and stilbene. The cis-trans isomerization is modeled and in each case the results agree well with those obtained from other computational and empirical methods. Next, we use the tight-binding model to simulate...
Jones, Nathan
2012-10-19
mechanisms is to reduce the computational time needed to simulate a problem. The focus of this work is on the validity of reduced methane-air combustion mechanisms, particularly pertaining to satisfying the entropy inequality. While much of this work involves...
LÃ¶hner, Rainald
Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, 229-8510, Japan Abstract A code to simulate. Introduction A detonation is a shock wave sustained by the energy released by combustion. The typical case even for the current study. Recently, detonation has been applied to the next generation engines
Numerical simulation of Lewis number effects on lean premixed turbulent flames
Bell, John B.
turbulent flames for lean hydrogen, propane and methane mixtures in two dimensions. Each simulation is broken indicating local extinction. Keywords: turbulent premixed combustion, low Mach number flow for propane, methane and hydrogen using de- tailed chemistry and transport, corresponding to Le > 1, Le 1
Low level jet development during a numerically simulated return flow event
Igau, Richard Charles
1994-01-01
The evolution of the southerly low level jet during a return flow event is studied using output from the Penn State/NCAR Mesoscale Model (Version 4). Three geographically different southerly low level jets (LLJ's) develop in the simulation: one over...
Simulation of a Polar Low Case in the North Atlantic with different regional numerical models
Zahn, Matthias
by the DWD (German Weather Service) by means of their forecast model HRM (High Resolution Model) and another University Press, Cambridge. (a) CLM (b) REMO (c) HRM, DWD (d) BWK Figure 1: 1(a)- 1(c)10m wind velocity pressure from CLM and REMO simulations and HRM analysis, DWD, respectively, at 15/10/93, 6:00, 1(d) surface
Numerical simulation of a fuel droplet laden exothermic reacting mixing layer
Miller, Richard S.
the gas phase. The simulation parameters study the effects of the fuel composition, reaction stoichiometry role of carrier gas fuel to the reaction. Local flame extinction is markedly increased for non to the large occurrence in a variety of natural and practical applications, multiphase tur- bulent combustion
Lang, Richard Anthony
2004-09-30
of comminution in a sheared granular material. The model, based on the Discrete Element Method, simulates a layer of 2-D circular grains subjected to normal stress and sheared at constant velocity. An existing code was modified to allow grains to break when...
Wang, Bin
Tropical Cyclogenesis Associated with Rossby Wave Energy Dispersion of a Preexisting Typhoon. Part (1987) and Fiorino and Els- berry (1989) showed that a cyclonic vortex experiences Rossby wave energy) ABSTRACT The cyclogenesis events associated with the tropical cyclone (TC) energy dispersion are simulated
Pahn, T.; Jonkman, J.; Rolges, R.; Robertson, A.
2012-11-01
Physically measuring the dynamic responses of wind turbine support structures enables the calculation of the applied loads using an inverse procedure. In this process, inverse means deriving the inputs/forces from the outputs/responses. This paper presents results of a numerical verification of such an inverse load calculation. For this verification, the comprehensive simulation code FAST is used. FAST accounts for the coupled dynamics of wind inflow, aerodynamics, elasticity and turbine controls. Simulations are run using a 5-MW onshore wind turbine model with a tubular tower. Both the applied loads due to the instantaneous wind field and the resulting system responses are known from the simulations. Using the system responses as inputs to the inverse calculation, the applied loads are calculated, which in this case are the rotor thrust forces. These forces are compared to the rotor thrust forces known from the FAST simulations. The results of these comparisons are presented to assess the accuracy of the inverse calculation. To study the influences of turbine controls, load cases in normal operation between cut-in and rated wind speed, near rated wind speed and between rated and cut-out wind speed are chosen. The presented study shows that the inverse load calculation is capable of computing very good estimates of the rotor thrust. The accuracy of the inverse calculation does not depend on the control activity of the wind turbine.
Perez, Jean Carlos; Chandran, Benjamin D. G.
2013-10-20
We present direct numerical simulations of inhomogeneous reduced magnetohydrodynamic (RMHD) turbulence between the Sun and the Alfvén critical point. These are the first such simulations that take into account the solar-wind outflow velocity and the radial inhomogeneity of the background solar wind without approximating the nonlinear terms in the governing equations. RMHD turbulence is driven by outward-propagating Alfvén waves (z {sup +} fluctuations) launched from the Sun, which undergo partial non-WKB reflection to produce sunward-propagating Alfvén waves (z {sup –} fluctuations). We present 10 simulations with different values of the correlation time ?{sub c{sub sun}{sup +}} and perpendicular correlation length L{sub ?} of outward-propagating Alfvén waves at the coronal base. We find that between 15% and 33% of the z {sup +} energy launched into the corona dissipates between the coronal base and Alfvén critical point. Between 33% and 40% of this input energy goes into work on the solar-wind outflow, and between 22% and 36% escapes as z {sup +} fluctuations through the simulation boundary at r = r{sub A}. The z {sup ±} power spectra scale like k{sub perpendicular}{sup -?{sup ±}}, where k is the wavenumber in the plane perpendicular to B{sub 0}. In our simulation with the smallest value of ?{sub c{sub sun}{sup +}} (?2 minutes) and largest value of L{sub ?} (2 × 10{sup 4} km), we find that ?{sup +} decreases approximately linearly with increasing ln (r), reaching a value of 1.3 at r = 11.1 R{sub ?}. Our simulations with larger values of ?{sub c{sub sun}{sup +}} exhibit alignment between the contours of constant ?{sup +}, ?{sup –}, ?{sub 0}{sup +}, and ?{sub 0}{sup -}, where ?{sup ±} are the Elsässer potentials and ?{sub 0}{sup ±} are the outer-scale parallel Elsässer vorticities.
The LIGO Scientific Collaboration; the Virgo Collaboration; the NINJA-2 Collaboration; :; J. Aasi; B. P. Abbott; R. Abbott; T. Abbott; M. R. Abernathy; T. Accadia; F. Acernese; K. Ackley; C. Adams; T. Adams; P. Addesso; R. X. Adhikari; C. Affeldt; M. Agathos; N. Aggarwal; O. D. Aguiar; A. Ain; P. Ajith; A. Alemic; B. Allen; A. Allocca; D. Amariutei; M. Andersen; R. Anderson; S. B. Anderson; W. G. Anderson; K. Arai; M. C. Araya; C. Arceneaux; J. Areeda; S. M. Aston; P. Astone; P. Aufmuth; C. Aulbert; L. Austin; B. E. Aylott; S. Babak; P. T. Baker; G. Ballardin; S. W. Ballmer; J. C. Barayoga; M. Barbet; B. C. Barish; D. Barker; F. Barone; B. Barr; L. Barsotti; M. Barsuglia; M. A. Barton; I. Bartos; R. Bassiri; A. Basti; J. C. Batch; J. Bauchrowitz; Th. S. Bauer; B. Behnke; M. Bejger; M. G. Beker; C. Belczynski; A. S. Bell; C. Bell; G. Bergmann; D. Bersanetti; A. Bertolini; J. Betzwieser; P. T. Beyersdorf; I. A. Bilenko; G. Billingsley; J. Birch; S. Biscans; M. Bitossi; M. A. Bizouard; E. Black; J. K. Blackburn; L. Blackburn; D. Blair; S. Bloemen; M. Blom; O. Bock; T. P. Bodiya; M. Boer; G. Bogaert; C. Bogan; C. Bond; F. Bondu; L. Bonelli; R. Bonnand; R. Bork; M. Born; V. Boschi; Sukanta Bose; L. Bosi; C. Bradaschia; P. R. Brady; V. B. Braginsky; M. Branchesi; J. E. Brau; T. Briant; D. O. Bridges; A. Brillet; M. Brinkmann; V. Brisson; A. F. Brooks; D. A. Brown; D. D. Brown; F. Brückner; S. Buchman; T. Bulik; H. J. Bulten; A. Buonanno; R. Burman; D. Buskulic; C. Buy; L. Cadonati; G. Cagnoli; J. Calderón Bustillo; E. Calloni; J. B. Camp; P. Campsie; K. C. Cannon; B. Canuel; J. Cao; C. D. Capano; F. Carbognani; L. Carbone; S. Caride; A. Castiglia; S. Caudill; M. Cavaglià; F. Cavalier; R. Cavalieri; C. Celerier; G. Cella; C. Cepeda; E. Cesarini; R. Chakraborty; T. Chalermsongsak; S. J. Chamberlin; S. Chao; P. Charlton; E. Chassande-Mottin; X. Chen; Y. Chen; A. Chincarini; A. Chiummo; H. S. Cho; J. Chow; N. Christensen; Q. Chu; S. S. Y. Chua; S. Chung; G. Ciani; F. Clara; J. A. Clark; F. Cleva; E. Coccia; P. -F. Cohadon; A. Colla; C. Collette; M. Colombini; L. Cominsky; M. Constancio Jr.; A. Conte; D. Cook; T. R. Corbitt; M. Cordier; N. Cornish; A. Corpuz; A. Corsi; C. A. Costa; M. W. Coughlin; S. Coughlin; J. -P. Coulon; S. Countryman; P. Couvares; D. M. Coward; M. Cowart; D. C. Coyne; R. Coyne; K. Craig; J. D. E. Creighton; S. G. Crowder; A. Cumming; L. Cunningham; E. Cuoco; K. Dahl; T. Dal Canton; M. Damjanic; S. L. Danilishin; S. D'Antonio; K. Danzmann; V. Dattilo; H. Daveloza; M. Davier; G. S. Davies; E. J. Daw; R. Day; T. Dayanga; G. Debreczeni; J. Degallaix; S. Deléglise; W. Del Pozzo; T. Denker; T. Dent; H. Dereli; V. Dergachev; R. De Rosa; R. T. DeRosa; R. DeSalvo; S. Dhurandhar; M. Díaz; L. Di Fiore; A. Di Lieto; I. Di Palma; A. Di Virgilio; A. Donath; F. Donovan; K. L. Dooley; S. Doravari; S. Dossa; R. Douglas; T. P. Downes; M. Drago; R. W. P. Drever; J. C. Driggers; Z. Du; S. Dwyer; T. Eberle; T. Edo; M. Edwards; A. Effler; H. Eggenstein; P. Ehrens; J. Eichholz; S. S. Eikenberry; G. Endr?czi; R. Essick; T. Etzel; M. Evans; T. Evans; M. Factourovich; V. Fafone; S. Fairhurst; Q. Fang; S. Farinon; B. Farr; W. M. Farr; M. Favata; H. Fehrmann; M. M. Fejer; D. Feldbaum; F. Feroz; I. Ferrante; F. Ferrini; F. Fidecaro; L. S. Finn; I. Fiori; R. P. Fisher; R. Flaminio; J. -D. Fournier; S. Franco; S. Frasca; F. Frasconi; M. Frede; Z. Frei; A. Freise; R. Frey; T. T. Fricke; P. Fritschel; V. V. Frolov; P. Fulda; M. Fyffe; J. Gair; L. Gammaitoni; S. Gaonkar; F. Garufi; N. Gehrels; G. Gemme; E. Genin; A. Gennai; S. Ghosh; J. A. Giaime; K. D. Giardina; A. Giazotto; C. Gill; J. Gleason; E. Goetz; R. Goetz; L. Gondan; G. González; N. Gordon; M. L. Gorodetsky; S. Gossan; S. Goßler; R. Gouaty; C. Gräf; P. B. Graff; M. Granata; A. Grant; S. Gras; C. Gray; R. J. S. Greenhalgh; A. M. Gretarsson; P. Groot; H. Grote; K. Grover; S. Grunewald; G. M. Guidi; C. Guido; K. Gushwa; E. K. Gustafson; R. Gustafson; D. Hammer; G. Hammond; M. Hanke; J. Hanks; C. Hanna; J. Hanson; J. Harms; G. M. Harry; I. W. Harry; E. D. Harstad; M. Hart; M. T. Hartman; C. -J. Haster; K. Haughian; A. Heidmann; M. Heintze; H. Heitmann; P. Hello; G. Hemming; M. Hendry; I. S. Heng; A. W. Heptonstall; M. Heurs; M. Hewitson; S. Hild; D. Hoak; K. A. Hodge; K. Holt; S. Hooper; P. Hopkins; D. J. Hosken; J. Hough; E. J. Howell; Y. Hu; B. Hughey; S. Husa; S. H. Huttner; M. Huynh; T. Huynh-Dinh; D. R. Ingram; R. Inta; T. Isogai; A. Ivanov; B. R. Iyer; K. Izumi; M. Jacobson; E. James; H. Jang; P. Jaranowski; Y. Ji; F. Jiménez-Forteza; W. W. Johnson; D. I. Jones; R. Jones; R. J. G. Jonker; L. Ju; Haris K; P. Kalmus; V. Kalogera; S. Kandhasamy; G. Kang; J. B. Kanner; J. Karlen; M. Kasprzack; E. Katsavounidis; W. Katzman; H. Kaufer; K. Kawabe; F. Kawazoe; F. Kéfélian; G. M. Keiser; D. Keitel; D. B. Kelley; W. Kells; A. Khalaidovski
2014-01-05
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave astrophysics communities. The purpose of NINJA is to study the ability to detect gravitational waves emitted from merging binary black holes and recover their parameters with next-generation gravitational-wave observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete binary black hole hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a "blind injection challenge" similar to that conducted in recent LIGO and Virgo science runs, we added 7 hybrid waveforms to two months of data recolored to predictions of Advanced LIGO and Advanced Virgo sensitivity curves during their first observing runs. The resulting data was analyzed by gravitational-wave detection algorithms and 6 of the waveforms were recovered with false alarm rates smaller than 1 in a thousand years. Parameter estimation algorithms were run on each of these waveforms to explore the ability to constrain the masses, component angular momenta and sky position of these waveforms. We also perform a large-scale monte-carlo study to assess the ability to recover each of the 60 hybrid waveforms with early Advanced LIGO and Advanced Virgo sensitivity curves. Our results predict that early Advanced LIGO and Advanced Virgo will have a volume-weighted average sensitive distance of 300Mpc (1Gpc) for $10M_{\\odot}+10M_{\\odot}$ ($50M_{\\odot}+50M_{\\odot}$) binary black hole coalescences. We demonstrate that neglecting the component angular momenta in the waveform models used in matched-filtering will result in a reduction in sensitivity for systems with large component angular momenta. [Abstract abridged for ArXiv, full version in PDF
NUMERICAL SIMULATIONS OF CHROMOSPHERIC ANEMONE JETS ASSOCIATED WITH MOVING MAGNETIC FEATURES
Yang, Liping; He, Jiansen; Tu, Chuanyi; Zhang, Lei; Peter, Hardi; Feng, Xueshang; Zhang, Shaohua
2013-11-01
Observations with the space-based solar observatory Hinode show that small-scale magnetic structures in the photosphere are found to be associated with a particular class of jets of plasma in the chromosphere called anemone jets. The goal of our study is to conduct a numerical experiment of such chromospheric anemone jets related to the moving magnetic features (MMFs). We construct a 2.5 dimensional numerical MHD model to describe the process of magnetic reconnection between the MMFs and the pre-existing ambient magnetic field, which is driven by the horizontal motion of the magnetic structure in the photosphere. We include thermal conduction parallel to the magnetic field and optically thin radiative losses in the corona to account for a self-consistent description of the evaporation process during the heating of the plasma due to the reconnection process. The motion of the MMFs leads to the expected jet and our numerical results can reproduce many observed characteristics of chromospheric anemone jets, topologically and quantitatively. As a result of the tearing instability, plasmoids are generated in the reconnection process that are consistent with the observed bright moving blobs in the anemone jets. An increase in the thermal pressure at the base of the jet is also driven by the reconnection, which induces a train of slow-mode shocks propagating upward. These shocks are a secondary effect, and only modulate the outflow of the anemone jet. The jet itself is driven by the energy input due to the reconnection of the MMFs and the ambient magnetic field.
Weakly first-order phase transitions: the epsilon expansion vs. numerical simulations
Peter Arnold; Stephen R. Sharpe; Laurence G. Yaffe; Yan Zhang
1996-10-31
Some phase transitions of cosmological interest may be weakly first-order and cannot be analyzed by a simple perturbative expansion around mean field theory. We propose a simple two-scalar model--the cubic anisotropy model--as a foil for theoretical techniques to study such transitions, and we review its similarities and dissimilarities to the electroweak phase transition in the early universe. We present numerical Monte Carlo results for various discontinuities across very weakly first-order transitions in this model and, as an example, compare them to epsilon-expansion results. For this purpose, we have computed through next-to-next-to-leading order in epsilon.
Grossman, A; Molenkamp, C R
1999-08-25
A proposal has been made to establish a high density global network of atmospheric micro transponders to record time, temperature, and wind data with time resolution of {le} 1 minute, temperature accuracy of {+-} 1 K, spatial resolution no poorer than {approx}3km horizontally and {approx}0.1km vertically, and 2-D speed accuracy of {le} 1m/s. This data will be used in conjunction with advanced numerical weather prediction models to provide increases in the reliability of long range weather forecasts. Major advances in data collection technology will be required to provide the proposed high-resolution data collection network. Systems studies must be undertaken to determine insertion requirements, spacing, and evolution of the transponder ensemble, which will be used to collect the data. Numerical models which provide realistic global weather pattern simulations must be utilized in order to perform these studies. A global circulation model with a 3{sup o} horizontal resolution has been used for initial simulations of the generation and evolution of transponder distributions. These studies indicate that reasonable global coverage of transponders can be achieved by a launch scenario consisting of the sequential launch of transponders at specified heights from a globally distributed set of launch sites.
Numerical simulation of ion charge breeding in electron beam ion source
Zhao, L., E-mail: zhao@far-tech.com; Kim, Jin-Soo [FAR-TECH, Inc., San Diego, California 92122 (United States)] [FAR-TECH, Inc., San Diego, California 92122 (United States)
2014-02-15
The Electron Beam Ion Source particle-in-cell code (EBIS-PIC) tracks ions in an EBIS electron beam while updating electric potential self-consistently and atomic processes by the Monte Carlo method. Recent improvements to the code are reported in this paper. The ionization module has been improved by using experimental ionization energies and shell effects. The acceptance of injected ions and the emittance of extracted ion beam are calculated by extending EBIS-PIC to the beam line transport region. An EBIS-PIC simulation is performed for a Cs charge-breeding experiment at BNL. The charge state distribution agrees well with experiments, and additional simulation results of radial profiles and velocity space distributions of the trapped ions are presented.
Numerical simulations of solar energetic particle event timescales associated with ICMES
Qi, S -Y; Wang, Y
2015-01-01
Recently, S.W. Kahler studied the solar energetic particle (SEP) event timescales associated with coronal mass ejections (CMEs) from spacecraft data analysis. They obtained different timescales of SEP events, such as TO, the onset time from CME launch to SEP onset, TR, the rise time from onset to half the peak intensity (0.5Ip), and TD, the duration of the SEP intensity above 0.5Ip. In this work, we solve SEPs transport equation considering ICME shocks as energetic particle sources. Our simulations show similar results to Kahler's spacecraft data analysis that the weighted average of TD increases with both CME speed and width. Besides, our simulations show the results which were not achieved from the observation data analysis, i.e., TD is directly dependent on CME speed, but not dependent on CME width.
Numerical simulation of high-speed penetration-perforation dynamics in layered armor shields
Ayzenberg-Stepanenko, Mark
2012-01-01
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.
Numerical simulation of high-speed penetration-perforation dynamics in layered armor shields
Mark Ayzenberg-Stepanenko; Grigory Osharovich
2012-03-07
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.
Final Report: A Model Management System for Numerical Simulations of Subsurface Processes
Zachmann, David
2013-10-07
The DOE and several other Federal agencies have committed significant resources to support the development of a large number of mathematical models for studying subsurface science problems such as groundwater flow, fate of contaminants and carbon sequestration, to mention only a few. This project provides new tools to help decision makers and stakeholders in subsurface science related problems to select an appropriate set of simulation models for a given field application.
Egorov, I.
2014-06-15
This paper describes the development of a computation model of a pulsed voltage generator for a repetitive electron accelerator. The model is based on a principle circuit of the generator, supplemented with the parasitics elements of the construction. Verification of the principle model was achieved by comparison of simulation with experimental results, where reasonable agreement was demonstrated for a wide range of generator load resistance.
Numerical Simulation of the Flow of a Power Law Fluid in an Elbow Bend
Kanakamedala, Karthik
2010-07-14
equations are given by, ????? = ????? + ?? + ??? where, ? is the Laplacian operator ? is the density of the body ? is the body force ? is the velocity vector However, the fluid being dealt within the problem is a non-Newtonian power law fluid... parameters. This problem finds applications mainly in the food and polymer industries where non-Newtonian fluids flow through different piping sections. The elbow geometry used for performing the simulations consists of a straight portion of ??? both after...
Karra, Satish
2009-05-15
[35] developed a stability analysis for the ax- isymmetric Rayleigh instability as well as the non-axisymmetric whipping instability in Newtonian fluids. According to them, the Rayleigh instability due to electrical forces is equivalent to the surface... for viscoelasticity between the beads. . . . . . . . 19 7 Typical result for the discrete particle model showing the bending loop in the jet. Top view shows that the envelope of the jet trajectory is a cone. The number of beads for this simulation N = 100 and non...
Li, X.; Li, N.; Fang, F.; Zhao, D.
2006-01-01
spraying, can be distinctly seen in the shrinkage section of the crossbeam bottom and exists a sticking point in the backward position. The distance ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency Vol.IV-3-1 augments along... analysis Fig.6. is the airflow velocity simulated results in the plenum, the velocity of the shrinkage section in the crossbeam bottom is biggest, it is obvious that there are many eddies in the back corner of the crossbeam (against velocity direction...
Marxen, Olaf, E-mail: olaf.marxen@vki.ac.be [Center for Turbulence Research, Building 500, Stanford University, Stanford, CA 94305-3035 (United States) [Center for Turbulence Research, Building 500, Stanford University, Stanford, CA 94305-3035 (United States); Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo, 72, 1640 Rhode-St-Genèse (Belgium); Magin, Thierry E. [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo, 72, 1640 Rhode-St-Genèse (Belgium)] [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo, 72, 1640 Rhode-St-Genèse (Belgium); Shaqfeh, Eric S.G.; Iaccarino, Gianluca [Center for Turbulence Research, Building 500, Stanford University, Stanford, CA 94305-3035 (United States)] [Center for Turbulence Research, Building 500, Stanford University, Stanford, CA 94305-3035 (United States)
2013-12-15
A new numerical method is presented here that allows to consider chemically reacting gases during the direct numerical simulation of a hypersonic fluid flow. The method comprises the direct coupling of a solver for the fluid mechanical model and a library providing the physio-chemical model. The numerical method for the fluid mechanical model integrates the compressible Navier–Stokes equations using an explicit time advancement scheme and high-order finite differences. This Navier–Stokes code can be applied to the investigation of laminar-turbulent transition and boundary-layer instability. The numerical method for the physio-chemical model provides thermodynamic and transport properties for different gases as well as chemical production rates, while here we exclusively consider a five species air mixture. The new method is verified for a number of test cases at Mach 10, including the one-dimensional high-temperature flow downstream of a normal shock, a hypersonic chemical reacting boundary layer in local thermodynamic equilibrium and a hypersonic reacting boundary layer with finite-rate chemistry. We are able to confirm that the diffusion flux plays an important role for a high-temperature boundary layer in local thermodynamic equilibrium. Moreover, we demonstrate that the flow for a case previously considered as a benchmark for the investigation of non-equilibrium chemistry can be regarded as frozen. Finally, the new method is applied to investigate the effect of finite-rate chemistry on boundary layer instability by considering the downstream evolution of a small-amplitude wave and comparing results with those obtained for a frozen gas as well as a gas in local thermodynamic equilibrium.
Numerical simulation of a thermoacoustic refrigerator. 2: Stratified flow around the stack
Worlikar, A.S.; Knio, O.M.; Klein, R.
1998-08-10
The unsteady, two-dimensional, thermally stratified flow in the neighborhood of an idealized thermoacoustic stack is analyzed using a low-Mach-number model that extends the adiabatic flow scheme developed in part 1 (Journal of Computational Physics 127, 424 (1996)). The extension consists of incorporation of numerical solvers for the energy equations in the fluid and the stack plates, and construction and implementation of fast Poisson solver for the velocity potential based on a domain decomposition/boundary Green`s function technique. The unsteady computations are used to predict the steady-state, acoustically generated temperature gradient across a two-dimensional couple and to analyze its dependence on the amplitude of the prevailing resonant wave. Computed results are compared to theoretical predictions and experimental data.
Numerical simulation study on fluid dynamics of plasma window using argon
Huang, S.; Zhu, K.; Shi, B. L.; Lu, Y. R.; Hershcovitch, A.; Yang, L.; Zhang, X. Y.; Wei, G. D.
2013-07-15
In this paper, a numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the arc and flow field of plasma window, which is used as a windowless vacuum sealing device. The gas inlet, arc creation-developing and plasma expansion segments are all incorporated together in the integral model. An axis-symmetry cathode structure (hollow cathode) is used in the model. Current distribution of the arc is presented and discussed. The temperature, velocity, and pressure field are presented to show the physical mechanisms for the high pressure gap within the plasma window. Flow acceleration and viscosity effect are concluded as the main reasons for the pressure drop. The result for the pressure distribution in the cylindrical tube section has a good agreement with the analytical model. The validation for the sealing ability of plasma window is verified.
Three dimensional numerical simulations of the UPS-292 stratified charge engine
O'Rourke, P.J.; Amsden, A.A.
1987-01-01
The authors present and analyze three-dimensional calculations of the spray, mixing and combustion in the UPS-292 stratified charge engine for three different operating conditions, corresponding to overall air-fuel ratios between 22.4 and 61.0. The numerical calculations are performed with KIVA, a multidimensional arbitrary-mesh, finite-difference hydrodynamics program for internal combustion engine applications. The calculations use a mesh of 10,000 computational cells. Each operating condition is calculated from intake valve closure at 118/sup 0/ BTDC to 90/sup 0/ ATDC and requires approximately three hours of CRAY-XMP computer time. Combustion occurs primarily in the wake of the spark plug, and to include the effects of the spark plug on the flow field, we use a novel internal obstacle treatment. The methodology, in which internal obstacles are represented by computational particles, promises to be applicable to the calculation of the flows around intake and exhaust valves.
Hakan Ozaltun & Herman Shen
2011-11-01
This article presents assessment of the mechanical behavior of U-10wt% Mo (U10Mo) alloy based monolithic fuel plates subject to irradiation. Monolithic, plate-type fuel is a new fuel form being developed for research and test reactors to achieve higher uranium densities within the reactor core to allow the use of low-enriched uranium fuel in high-performance reactors. Identification of the stress/strain characteristics is important for understanding the in-reactor performance of these plate-type fuels. For this work, three distinct cases were considered: (1) fabrication induced residual stresses (2) thermal cycling of fabricated plates; and finally (3) transient mechanical behavior under actual operating conditions. Because the temperatures approach the melting temperature of the cladding during the fabrication and thermal cycling, high temperature material properties were incorporated to improve the accuracy. Once residual stress fields due to fabrication process were identified, solution was used as initial state for the subsequent simulations. For thermal cycling simulation, elasto-plastic material model with thermal creep was constructed and residual stresses caused by the fabrication process were included. For in-service simulation, coupled fluid-thermal-structural interaction was considered. First, temperature field on the plates was calculated and this field was used to compute the thermal stresses. For time dependent mechanical behavior, thermal creep of cladding, volumetric swelling and fission induced creep of the fuel foil were considered. The analysis showed that the stresses evolve very rapidly in the reactor. While swelling of the foil increases the stress of the foil, irradiation induced creep causes stress relaxation.
Simulation of surface waves with porous boundaries in a 2-D numerical wave tank
Koo, Weoncheol
1999-01-01
for the degree of MASTER OF SCIENCE Approved as to style and content by: Moo-Hyu Kim (Chair of Committee) Hamn-Chi g Chen (Member) Robert O. Reid (Member) M. Nied e i ( ead of Departm nt) May 1999 Major Subject: Ocean Engineering ABSTRACT Simulation.... Moo-Hyun Kim for the guidance, assistance and supervision he has shown in completing this thesis. The patience and encouragement he has shown when various problems occurred are much appreciated. I also want to thank Dr. Hamn-Ching Chen...
Numerical Simulation of Earth Pressure on Head Chamber of Shield Machine with FEM
Li Shouju; Kang Chengang [State Key Laboratory of structural analysis for industrial equipment, Dalian University of Technology, Dalian 116023 (China); Sun, Wei [School of Mechanical Engineering, Dalian University of Technology, Dalian 116023 (China); Shangguan Zichang [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116023 (China); Institute of Civil Engineering, Dalian Fishery University, Dalian 116023 (China)
2010-05-21
Model parameters of conditioned soils in head chamber of shield machine are determined based on tree-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated in different aperture ratio cases for rotating cutterhead of shield machine. Relationship between pressure transportation factor and aperture ratio of shield machine is proposed by using aggression analysis.
Non-linear numerical simulations of magneto-acoustic wave propagation in small-scale flux tubes
E. Khomenko; M. Collados; T. Felipe
2008-01-25
We present results of non-linear, 2D, numerical simulations of magneto-acoustic wave propagation in the photosphere and chromosphere of small-scale flux tubes with internal structure. Waves with realistic periods of three to five minutes are studied, after applying horizontal and vertical oscillatory perturbations to the equilibrium model. Spurious reflections of shock waves from the upper boundary are minimized thanks to a special boundary condition. This has allowed us to increase the duration of the simulations and to make it long enough to perform a statistical analysis of oscillations. The simulations show that deep horizontal motions of the flux tube generate a slow (magnetic) mode and a surface mode. These modes are efficiently transformed into a slow (acoustic) mode in the vA acoustic) mode propagates vertically along the field lines, forms shocks and remains always within the flux tube. It might deposit effectively the energy of the driver into the chromosphere. When the driver oscillates with a high frequency, above the cut-off, non-linear wave propagation occurs with the same dominant driver period at all heights. At low frequencies, below the cut-off, the dominant period of oscillations changes with height from that of the driver in the photosphere to its first harmonic (half period) in the chromosphere. Depending on the period and on the type of the driver, different shock patterns are observed.
Chang Hyun Baek; Hyesung Kang; Jongsoo Kim; Dongsu Ryu
2005-06-08
We study thermal-gravitational instability in simplified models for protogalactic halos using three-dimensional hydrodynamic simulations. The simulations followed the evolution of gas with radiative cooling down to T = 10^4 K, background heating, and self-gravity. Then cooled and condensed clouds were identified and their physical properties were examined in detail. During early stage clouds start to form around initial density peaks by thermal instability. Small clouds appear first and they are pressure-bound. Subsequently, the clouds grow through compression by the background pressure as well as gravitational infall. During late stage cloud-cloud collisions become important, and clouds grow mostly through gravitational merging. Gravitationally bound clouds with mass M_c > ~6 X 10^6 Msun are found in the late stage. They are approximately in virial equilibrium and have radius R_c = \\~150 - 200 pc. Those clouds have gained angular momentum through tidal torque as well as merging, so they have large angular momentum with the spin parameter ~ 0.3. The clouds formed in a denser background tend to have smaller spin parameters. We discuss briefly the implications of our results on the formation of protoglobular cluster clouds in protogalactic halos. (abridged)
Numerical magnetohydrodynamic simulations of expanding flux ropes: Influence of boundary driving
Tacke, Thomas; Dreher, Jürgen [Theoretische Physik I, Ruhr-Universität Bochum, Bochum (Germany)] [Theoretische Physik I, Ruhr-Universität Bochum, Bochum (Germany); Sydora, Richard D. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)] [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)
2013-07-15
The expansion dynamics of a magnetized, current-carrying plasma arch is studied by means of time-dependent ideal MHD simulations. Initial conditions model the setup used in recent laboratory experiments that in turn simulate coronal loops [J. Tenfelde et al., Phys. Plasmas 19, 072513 (2012); E. V. Stenson and P. M. Bellan, Plasma Phys. Controlled Fusion 54, 124017 (2012)]. Boundary conditions of the electric field at the “lower” boundary, intersected by the arch, are chosen such that poloidal magnetic flux is injected into the domain, either localized at the arch footpoints themselves or halfway between them. These conditions are motivated by the tangential electric field expected to exist in the laboratory experiments due to the external circuit that drives the plasma current. The boundary driving is found to systematically enhance the expansion velocity of the plasma arch. While perturbations at the arch footpoints also deform its legs and create characteristic elongated segments, a perturbation between the footpoints tends to push the entire structure upwards, retaining an ellipsoidal shape.
Schenone, Elisa; Gerbeau, Jean-Frédéric
2015-01-01
This work is dedicated to the simulation of full cycles of the electrical activity of the heart and the corresponding body surface potential. The model is based on a realistic torso and heart anatomy, including ventricles and atria. One of the specificities of our approach is to model the atria as a surface, which is the kind of data typically provided by medical imaging for thin volumes. The bidomain equations are considered in their usual formulation in the ventricles, and in a surface formulation on the atria. Two ionic models are used: the Courtemanche-Ramirez-Nattel model on the atria, and the "Minimal model for human Ventricular action potentials" (MV) by Bueno-Orovio, Cherry and Fenton in the ventricles. The heart is weakly coupled to the torso by a Robin boundary condition based on a resistor- capacitor transmission condition. Various ECGs are simulated in healthy and pathological conditions (left and right bundle branch blocks, Bachmann's bundle block, Wolff-Parkinson-White syndrome). To assess the n...
Two-dimensional numerical simulation of a Stirling engine heat exchanger
Ibrahim, M.B.; Tew, R.C.; Dudenhoefer, J.E.
1994-09-01
This paper describes the first phase of an effort to develop multidimensional models of Stirling engine components; the ultimate goal is to model an entire engine working space. More specifically, this paper describes parallel plate and tubular heat exchanger models with emphasis on the central part of the channel (i.e., ignoring hydrodynamic and thermal end effects). The model assumes: Laminar, incompressible flow with constant thermophysical properties. In addition, a constant axial temperature gradient is imposed. The governing equations, describing the model, have been solved Crack-Nicloson finite-difference scheme. Model predictions have been compared with analytical solutions for oscillating/reversing flow and heat transfer in order to check numerical accuracy. The simplifying assumptions will later be relaxed to permit modeling of incompressible, laminar/turbulent flow that occurs in Stirling heat exchanger. Excellent agreement has been obtained for the model predictions with analytical solutions available for both flow in circular tubes and between parallel plates. Also the heat transfer computational results are in good agreement with the heat transfer analytical results for parallel plates.
PROBABILISTIC SIMULATION OF SUBSURFACE FLUID FLOW: A STUDY USING A NUMERICAL SCHEME
Buscheck, Timothy Eric
1980-03-01
There has been an increasing interest in probabilistic modeling of hydrogeologic systems. The classical approach to groundwater modeling has been deterministic in nature, where individual layers and formations are assumed to be uniformly homogeneous. Even in the case of complex heterogeneous systems, the heterogeneities describe the differences in parameter values between various layers, but not within any individual layer. In a deterministic model a single-number is assigned to each hydrogeologic parameter, given a particular scale of interest. However, physically there is no such entity as a truly uniform and homogeneous unit. Single-number representations or deterministic predictions are subject to uncertainties. The approach used in this work models such uncertainties with probabilistic parameters. The resulting statistical distributions of output variables are analyzed. A numerical algorithm, based on axiomatic principles of probability theory, performs arithmetic operations between probability distributions. Two subroutines are developed from the algorithm and incorporated into the computer program TERZAGI, which solves groundwater flow problems in saturated, multi-dimensional systems. The probabilistic computer program is given the name, PROGRES. The algorithm has been applied to study the following problems: one-dimensional flow through homogeneous media, steady-state and transient flow conditions, one-dimensional flow through heterogeneous media, steady-state and transient flow conditions, and two-dimensional steady-stte flow through heterogeneous media. The results are compared with those available in the literature.
Wainwright, Carroll L.; Aguirre, Anthony [SCIPP and Department of Physics, University of California, Santa Cruz, CA, 95064 (United States); Johnson, Matthew C. [Department of Physics and Astronomy, York University, Toronto, On, M3J 1P3 (Canada); Peiris, Hiranya V. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Lehner, Luis [Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada); Liebling, Steven L., E-mail: cwainwri@ucsc.edu, E-mail: mjohnson@perimeterinstitute.ca, E-mail: h.peiris@ucl.ac.uk, E-mail: aguirre@scipp.ucsc.edu, E-mail: llehner@perimeterinstitute.ca, E-mail: steve.liebling@liu.edu [Department of Physics, Long Island University, Brookville, NY, 11548 (United States)
2014-03-01
The theory of eternal inflation in an inflaton potential with multiple vacua predicts that our universe is one of many bubble universes nucleating and growing inside an ever-expanding false vacuum. The collision of our bubble with another could provide an important observational signature to test this scenario. We develop and implement an algorithm for accurately computing the cosmological observables arising from bubble collisions directly from the Lagrangian of a single scalar field. We first simulate the collision spacetime by solving Einstein's equations, starting from nucleation and ending at reheating. Taking advantage of the collision's hyperbolic symmetry, the simulations are performed with a 1+1-dimensional fully relativistic code that uses adaptive mesh refinement. We then calculate the comoving curvature perturbation in an open Friedmann-Robertson-Walker universe, which is used to determine the temperature anisotropies of the cosmic microwave background radiation. For a fiducial Lagrangian, the anisotropies are well described by a power law in the cosine of the angular distance from the center of the collision signature. For a given form of the Lagrangian, the resulting observational predictions are inherently statistical due to stochastic elements of the bubble nucleation process. Further uncertainties arise due to our imperfect knowledge about inflationary and pre-recombination physics. We characterize observational predictions by computing the probability distributions over four phenomenological parameters which capture these intrinsic and model uncertainties. This represents the first fully-relativistic set of predictions from an ensemble of scalar field models giving rise to eternal inflation, yielding significant differences from previous non-relativistic approximations. Thus, our results provide a basis for a rigorous confrontation of these theories with cosmological data.
Numerical simulation of a wave-guide mixing layer on a Cray C-90
Greenough, J.A.; Crutchfield, W.Y.; Rendleman, C.A.
1995-05-19
The development of a three-dimensional spatially evolving compressible mixing layer is investigated numerically using a parallel implementation of Adaptive Mesh Refinement (AMR) on a Cray C-90. The parallel implementation allowed the flow to be highly resolved while significantly reducing the wall-clock runtime. A sustained computation rate of 5.3 Gigaflops including I/O was obtained for a typical production run on a 16 processor machine. A novel mixing layer configuration is investigated where a pressure mismatch is maintained between the two inlet streams. In addition, the sonic character of the two streams is sufficiently different so that the pressure relief wave is trapped in the high speed stream. The trapped wave forces the mixing layer to form a characteristic cellular pattern. The cellular structure introduces curvature into the mixing layer that excites centrifugal instabilities characterized by large-scale counter-rotating vortical pairs embedded within the mixing layer. These are the dominant feature of the flow. Visualizations of these structures in cross-section show the pumping action which lifts dense fluid up into light gas. This effect has a strong impact on mixing enhancement as monitored by a conserved scalar formulation. Once the large-scale structures axe well established in the flow and undergo intensification from favorable velocity gradients, the time-averaged integrated product shows almost a four-fold increase. A spectral analysis of the flow-field over the cellular structures, as part of a full space-time analysis, shows these structures to be zero-frequency modes that develop from low level essentially broad-banded noise. This characterization of the vortical structures and their appearance is consistent with a recent linear stability analysis, of a mixing layer over a curved wall that predicts the most unstable modes to be zero frequency streamwise vortices.
Toriumi, Shin; Katsukawa, Yukio
2015-01-01
Light bridges, the bright structure dividing umbrae in sunspot regions, show various activity events. In Paper I, we reported on analysis of multi-wavelength observations of a light bridge in a developing active region (AR) and concluded that the activity events are caused by magnetic reconnection driven by magnetconvective evolution. The aim of this second paper is to investigate the detailed magnetic and velocity structures and the formation mechanism of light bridges. For this purpose, we analyze numerical simulation data from a radiative magnetohydrodynamics model of an emerging AR. We find that a weakly-magnetized plasma upflow in the near-surface layers of the convection zone is entrained between the emerging magnetic bundles that appear as pores at the solar surface. This convective upflow continuously transports horizontal fields to the surface layer and creates a light bridge structure. Due to the magnetic shear between the horizontal fields of the bridge and the vertical fields of the ambient pores,...
Numerical simulation of a thermoacoustic refrigerator. I. Unsteady adiabatic flow around the stack
Worlikar, A.S.; Knio, O.M.
1996-09-01
A low Mach-number compressible flow model for the simulation of acoustically driven flow in a thermoacoustic stack is constructed. The model is based on the assumption that the acoustic wavelength is much larger than the characteristic hydrodynamic lengthscale. Thus, a simplified description of the flow is obtained which still retains the essential features of acoustically induced velocity oscillations near solid boundaries. A vorticity-based formulation of the governing equation is derived which relies on the Helmholtz decomposition of the velocity vector into irrotational and divergence-free components. Irrotational motion is used to represent the action of acoustic waves. Meanwhile the divergence-free velocity component is used to capture the nonlinear vortical perturbations due to no-slip boundaries. A simplified version of the model is applied to analyze unsteady flow in the neighborhood of an idealized thermo-acoustic stack which consists of a periodic array of thin plates placed in an acoustic standing wave. Computed results are used to analyze, for different stack configurations, the nonlinear response of the flow to different acoustic driving amplitudes and frequencies. In particular, it is shown that the flow is dominated by the motion of vortices which result from the shedding of boundary layers from the edges of the stack. The dependence of energy losses on stack configuration and operating conditions is also examined. 28 refs., 23 figs., 2 tabs.
Neeraj Gupta
2008-03-31
A series of numerical simulations of carbon dioxide (CO{sub 2}) injection were conducted as part of a program to assess the potential for geologic sequestration in deep geologic reservoirs (the Rose Run and Copper Ridge formations), at the American Electric Power (AEP) Mountaineer Power Plant outside of New Haven, West Virginia. The simulations were executed using the H{sub 2}O-CO{sub 2}-NaCl operational mode of the Subsurface Transport Over Multiple Phases (STOMP) simulator (White and Oostrom, 2006). The objective of the Rose Run formation modeling was to predict CO{sub 2} injection rates using data from the core analysis conducted on the samples. A systematic screening procedure was applied to the Ohio River Valley CO{sub 2} storage site utilizing the Features, Elements, and Processes (FEP) database for geological storage of CO{sub 2} (Savage et al., 2004). The objective of the screening was to identify potential risk categories for the long-term geological storage of CO{sub 2} at the Mountaineer Power Plant in New Haven, West Virginia. Over 130 FEPs in seven main classes were assessed for the project based on site characterization information gathered in a geological background study, testing in a deep well drilled on the site, and general site conditions. In evaluating the database, it was apparent that many of the items were not applicable to the Mountaineer site based its geologic framework and environmental setting. Nine FEPs were identified for further consideration for the site. These FEPs generally fell into categories related to variations in subsurface geology, well completion materials, and the behavior of CO{sub 2} in the subsurface. Results from the screening were used to provide guidance on injection system design, developing a monitoring program, performing reservoir simulations, and other risk assessment efforts. Initial work indicates that the significant FEPs may be accounted for by focusing the storage program on these potential issues. The screening method was also useful in identifying unnecessary items that were not significant given the site-specific geology and proposed scale of the Ohio River Valley CO{sub 2} Storage Project. Overall, the FEP database approach provides a comprehensive methodology for assessing potential risk for a practical CO{sub 2} storage application. An integrated numerical fate and transport model was developed to enable risk and consequence assessment at field scale. Results show that such an integrated modeling effort would be helpful in meeting the project objectives (such as site characterization, engineering, permitting, monitoring and closure) during different stages. A reservoir-scale numerical model was extended further to develop an integrated assessment framework which can address the risk and consequence assessment, monitoring network design and permitting guidance needs. The method was used to simulate sequestration of CO{sub 2} in moderate quantities at the Mountaineer Power Plant. Results indicate that at the relatively low injection volumes planned for pilot scale demonstration at this site, the risks involved are minor to negligible, owing to a thick, low permeability caprock and overburden zones. Such integrated modeling approaches coupled with risk and consequence assessment modeling are valuable to project implementation, permitting, monitoring as well as site closure.
A STELLAR WIND ORIGIN FOR THE G2 CLOUD: THREE-DIMENSIONAL NUMERICAL SIMULATIONS
De Colle, Fabio; Raga, A. C.; Contreras-Torres, Flavio F.; Toledo-Roy, Juan C.
2014-07-10
We present three-dimensional, adaptive mesh refinement simulations of G2, a cloud of gas moving in a highly eccentric orbit toward the galactic center. We assume that G2 originates from a stellar wind interacting with the environment of the Sgr A* black hole. The stellar wind forms a cometary bubble which becomes increasingly elongated as the star approaches periastron. A few months after periastron passage, streams of material begin to accrete on the central black hole with accretion rates M-dot ?10{sup ?8} M {sub ?} yr{sup –1}. Predicted Br? emission maps and position-velocity diagrams show an elongated emission resembling recent observations of G2. A large increase in luminosity is predicted by the emission coming from the shocked wind region during periastron passage. The observations, showing a constant Br? luminosity, remain puzzling, and are explained here assuming that the emission is dominated by the free-wind region. The observed Br? luminosity (?8 × 10{sup 30} erg s{sup –1}) is reproduced by a model with a v{sub w} = 50 km s{sup –1} wind velocity and a 10{sup –7} M {sub ?} yr{sup –1} mass-loss rate if the emission comes from the shocked wind. A faster and less dense wind reproduces the Br? luminosity if the emission comes from the inner, free-wind region. The extended cometary wind bubble, largely destroyed by the tidal interaction with the black hole, reforms a few years after periastron passage. As a result, the Br? emission is more compact after periastron passage.
Modeling-Computer Simulations At Valles Caldera - Sulphur Springs...
DOE-funding Unknown Notes A computer program capable of two-dimensional modeling of gravity data was used in interpreting gravity observations along profiles A--A' and B--B'...
Modeling-Computer Simulations At Valles Caldera - Redondo Geothermal...
DOE-funding Unknown Notes A computer program capable of two-dimensional modeling of gravity data was used in interpreting gravity observations along profiles A--A' and B--B'...
Modeling-Computer Simulations At Long Valley Caldera Geothermal...
surrounding a vertically dipping prolate spheroid source during an active period of time-dependent deformation between 1995 and 2000 at Long Valley caldera. We model a rapid...
Modeling-Computer Simulations At Dixie Valley Geothermal Area...
for noble gas abundances and their helium isotropic compositions. It was found that the geothermal fluids range from 0.70 to 0.76 Ra, and approximately 7.5% of the total helium...
Modeling-Computer Simulations At Long Valley Caldera Geothermal...
and seismic data was conducted in 2003 to investigate the cause of recent uplift of the resurgent dome. Notes Modeling of deformation and microgravity data suggests...
Modeling-Computer Simulations At Nw Basin & Range Region (Laney...
previous seismic experiments and earthquake-monitoring projects, and data donated from mining, geothermal, and petroleum companies. We also collected (May 2002 and August 2004) two...
Modeling-Computer Simulations At Walker-Lane Transitional Zone...
previous seismic experiments and earthquake-monitoring projects, and data donated from mining, geothermal, and petroleum companies. We also collected (May 2002 and August 2004) two...
Modeling-Computer Simulations At Long Valley Caldera Geothermal...
estimated temperatures ranging from 240 to 273C, then flow laterally to the east and mix with cool groundwater that infiltrate and recharge the system along ring fractures and...
Modeling-Computer Simulations At Nw Basin & Range Region (Blackwell...
systems References D. D. Blackwell, K. W. Wisian, M. C. Richards, Mark Leidig, Richard Smith, Jason McKenna (2003) Geothermal Resource Analysis And Structure Of Basin And Range...
Modeling-Computer Simulations At Northern Basin & Range Region...
systems References D. D. Blackwell, K. W. Wisian, M. C. Richards, Mark Leidig, Richard Smith, Jason McKenna (2003) Geothermal Resource Analysis And Structure Of Basin And Range...
Modeling-Computer Simulations At Dixie Valley Geothermal Area...
vein structure associated with ore deposits. References David D. Blackwell, Richard P. Smith, Al Waibel, Maria C. Richards, Patrick Stepp (2009) Why Basin and Range Systems are...
Modeling-Computer Simulations At Central Nevada Seismic Zone...
systems References D. D. Blackwell, K. W. Wisian, M. C. Richards, Mark Leidig, Richard Smith, Jason McKenna (2003) Geothermal Resource Analysis And Structure Of Basin And Range...
Modeling-Computer Simulations At Long Valley Caldera Geothermal...
LVEW are best matched using modeled solutions for a flow system consisting of a rock matrix with finite hydraulic conductivity cut by a steeply dipping fracture with infinite...
Modeling-Computer Simulations At White Mountains Area (Goff ...
useful DOE-funding Unknown Notes Review and identification of 24 potential sites for EGS development across the U.S., as well as modeling of the representative geologic systems...
Modeling-Computer Simulations At Fenton Hill HDR Geothermal Area...
useful DOE-funding Unknown Notes Review and identification of 24 potential sites for EGS development across the U.S., as well as modeling of the representative geologic systems...
Modeling-Computer Simulations At Dixie Valley Geothermal Area...
and Multi-Scale Geothermal Fluid Connections in the Dixie Valley-Central Nevada Seismic Belt Area- Implications from Mt Resistivity Surveying Additional References Retrieved from...
Modeling-Computer Simulations At Valles Caldera - Redondo Geothermal...
Keiiti Aki, Michael C. Fehler (1995) A Shallow Attenuating Anomaly Inside The Ring Fracture Of The Valles Caldera, New Mexico Additional References Retrieved from "http:...
Modeling-Computer Simulations (Combs, Et Al., 1999) | Open Energy
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Modeling-Computer Simulations (Laney, 2005) | Open Energy Information
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Modeling-Computer Simulations (Lewicki & Oldenburg, 2004) | Open Energy
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Modeling-Computer Simulations (Ozkocak, 1985) | Open Energy Information
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Modeling-Computer Simulations (Ranalli & Rybach, 2005) | Open Energy
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Modeling-Computer Simulations (Walker, Et Al., 2005) | Open Energy
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Modeling-Computer Simulations At Central Nevada Seismic Zone Region
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Modeling-Computer Simulations At Central Nevada Seismic Zone Region
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History ViewMayo, Maryland: Energy ResourcesDec 2005MinnehahaElectricInformation Walker, Et(Pritchett,
Modeling-Computer Simulations At Dixie Valley Geothermal Area (Blackwell,
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History ViewMayo, Maryland: Energy ResourcesDec 2005MinnehahaElectricInformation Walker,2010) |Et Al.,
Modeling-Computer Simulations At Dixie Valley Geothermal Area (Wannamaker,
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Modeling-Computer Simulations At Long Valley Caldera Geothermal Area
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History ViewMayo, Maryland: Energy ResourcesDec 2005MinnehahaElectricInformation2008) | Open(Battaglia,
Modeling-Computer Simulations At Long Valley Caldera Geothermal Area
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Modeling-Computer Simulations At Long Valley Caldera Geothermal Area
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Modeling-Computer Simulations At Valles Caldera - Redondo Geothermal Area
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Modeling-Computer Simulations At Valles Caldera - Sulphur Springs
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Modeling-Computer Simulations At Valles Caldera - Sulphur Springs
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Modeling-Computer Simulations At Yellowstone Region (Laney, 2005) | Open
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Modeling-Computer Simulations (Gritto & Majer) | Open Energy Information
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Modeling-Computer Simulations At Long Valley Caldera Geothermal Area
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Modeling-Computer Simulations At Long Valley Caldera Geothermal Area
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Modeling-Computer Simulations At Valles Caldera - Redondo Geothermal Area
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Rafa, S. Molins; Trebotich, D.; Steefel, C. I.; Shen, C.
2012-02-01
The scale-dependence of geochemical reaction rates hinders their use in continuum scale models intended for the interpretation and prediction of chemical fate and transport in subsurface environments such as those considered for geologic sequestration of CO{sub 2}. Processes that take place at the pore scale, especially those involving mass transport limitations to reactive surfaces, may contribute to the discrepancy commonly observed between laboratory-determined and continuum-scale or field rates. Here, the dependence of mineral dissolution rates on the pore structure of the porous media is investigated by means of pore scale modeling of flow and multicomponent reactive transport. The pore scale model is comprised of high performance simulation tools and algorithms for incompressible flow and conservative transport combined with a general-purpose multicomponent geochemical reaction code. The model performs direct numerical simulation of reactive transport based on an operator-splitting approach to coupling transport and reactions. The approach is validated with a Poiseuille flow single-pore experiment and verified with an equivalent 1D continuum-scale model of a capillary tube packed with calcite spheres. Using the case of calcite dissolution as an example, the high resolution model is used to demonstrate that non-uniformity in the flow field at the pore scale has the effect of decreasing the overall reactivity of the system, even when systems with identical reactive surface area are considered. The effect becomes more pronounced as the heterogeneity of the reactive grain packing increases, particularly where the flow slows sufficiently such that the solution approaches equilibrium locally and the average rate becomes transport-limited.
Kwon, Kyung; Fan, Liang-Shih; Zhou, Qiang; Yang, Hui
2014-09-30
A new and efficient direct numerical method with second-order convergence accuracy was developed for fully resolved simulations of incompressible viscous flows laden with rigid particles. The method combines the state-of-the-art immersed boundary method (IBM), the multi-direct forcing method, and the lattice Boltzmann method (LBM). First, the multi-direct forcing method is adopted in the improved IBM to better approximate the no-slip/no-penetration (ns/np) condition on the surface of particles. Second, a slight retraction of the Lagrangian grid from the surface towards the interior of particles with a fraction of the Eulerian grid spacing helps increase the convergence accuracy of the method. An over-relaxation technique in the procedure of multi-direct forcing method and the classical fourth order Runge-Kutta scheme in the coupled fluid-particle interaction were applied. The use of the classical fourth order Runge-Kutta scheme helps the overall IB-LBM achieve the second order accuracy and provides more accurate predictions of the translational and rotational motion of particles. The preexistent code with the first-order convergence rate is updated so that the updated new code can resolve the translational and rotational motion of particles with the second-order convergence rate. The updated code has been validated with several benchmark applications. The efficiency of IBM and thus the efficiency of IB-LBM were improved by reducing the number of the Lagragian markers on particles by using a new formula for the number of Lagrangian markers on particle surfaces. The immersed boundary-lattice Boltzmann method (IBLBM) has been shown to predict correctly the angular velocity of a particle. Prior to examining drag force exerted on a cluster of particles, the updated IB-LBM code along with the new formula for the number of Lagrangian markers has been further validated by solving several theoretical problems. Moreover, the unsteadiness of the drag force is examined when a fluid is accelerated from rest by a constant average pressure gradient toward a steady Stokes flow. The simulation results agree well with the theories for the short- and long-time behavior of the drag force. Flows through non-rotational and rotational spheres in simple cubic arrays and random arrays are simulated over the entire range of packing fractions, and both low and moderate particle Reynolds numbers to compare the simulated results with the literature results and develop a new drag force formula, a new lift force formula, and a new torque formula. Random arrays of solid particles in fluids are generated with Monte Carlo procedure and Zinchenko's method to avoid crystallization of solid particles over high solid volume fractions. A new drag force formula was developed with extensive simulated results to be closely applicable to real processes over the entire range of packing fractions and both low and moderate particle Reynolds numbers. The simulation results indicate that the drag force is barely affected by rotational Reynolds numbers. Drag force is basically unchanged as the angle of the rotating axis varies.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Schilling, Oleg; Mueschke, Nicholas J.
2010-10-18
Data from a 1152X760X1280 direct numerical simulation (DNS) of a transitional Rayleigh-Taylor mixing layer modeled after a small Atwood number water channel experiment is used to comprehensively investigate the structure of mean and turbulent transport and mixing. The simulation had physical parameters and initial conditions approximating those in the experiment. The budgets of the mean vertical momentum, heavy-fluid mass fraction, turbulent kinetic energy, turbulent kinetic energy dissipation rate, heavy-fluid mass fraction variance, and heavy-fluid mass fraction variance dissipation rate equations are constructed using Reynolds averaging applied to the DNS data. The relative importance of mean and turbulent production, turbulent dissipationmore »and destruction, and turbulent transport are investigated as a function of Reynolds number and across the mixing layer to provide insight into the flow dynamics not presently available from experiments. The analysis of the budgets supports the assumption for small Atwood number, Rayleigh/Taylor driven flows that the principal transport mechanisms are buoyancy production, turbulent production, turbulent dissipation, and turbulent diffusion (shear and mean field production are negligible). As the Reynolds number increases, the turbulent production in the turbulent kinetic energy dissipation rate equation becomes the dominant production term, while the buoyancy production plateaus. Distinctions between momentum and scalar transport are also noted, where the turbulent kinetic energy and its dissipation rate both grow in time and are peaked near the center plane of the mixing layer, while the heavy-fluid mass fraction variance and its dissipation rate initially grow and then begin to decrease as mixing progresses and reduces density fluctuations. All terms in the transport equations generally grow or decay, with no qualitative change in their profile, except for the pressure flux contribution to the total turbulent kinetic energy flux, which changes sign early in time (a countergradient effect). The production-to-dissipation ratios corresponding to the turbulent kinetic energy and heavy-fluid mass fraction variance are large and vary strongly at small evolution times, decrease with time, and nearly asymptote as the flow enters a self-similar regime. The late-time turbulent kinetic energy production-to-dissipation ratio is larger than observed in shear-driven turbulent flows. The order of magnitude estimates of the terms in the transport equations are shown to be consistent with the DNS at late-time, and also confirms both the dominant terms and their evolutionary behavior. These results are useful for identifying the dynamically important terms requiring closure, and assessing the accuracy of the predictions of Reynolds-averaged Navier-Stokes and large-eddy simulation models of turbulent transport and mixing in transitional Rayleigh-Taylor instability-generated flow.« less
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Schilling, Oleg [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Mueschke, Nicholas J. [Texas A and M Univ., College Station, TX (United States)
2010-01-01
Data from a 1152X760X1280 direct numerical simulation (DNS) of a transitional Rayleigh-Taylor mixing layer modeled after a small Atwood number water channel experiment is used to comprehensively investigate the structure of mean and turbulent transport and mixing. The simulation had physical parameters and initial conditions approximating those in the experiment. The budgets of the mean vertical momentum, heavy-fluid mass fraction, turbulent kinetic energy, turbulent kinetic energy dissipation rate, heavy-fluid mass fraction variance, and heavy-fluid mass fraction variance dissipation rate equations are constructed using Reynolds averaging applied to the DNS data. The relative importance of mean and turbulent production, turbulent dissipation and destruction, and turbulent transport are investigated as a function of Reynolds number and across the mixing layer to provide insight into the flow dynamics not presently available from experiments. The analysis of the budgets supports the assumption for small Atwood number, Rayleigh/Taylor driven flows that the principal transport mechanisms are buoyancy production, turbulent production, turbulent dissipation, and turbulent diffusion (shear and mean field production are negligible). As the Reynolds number increases, the turbulent production in the turbulent kinetic energy dissipation rate equation becomes the dominant production term, while the buoyancy production plateaus. Distinctions between momentum and scalar transport are also noted, where the turbulent kinetic energy and its dissipation rate both grow in time and are peaked near the center plane of the mixing layer, while the heavy-fluid mass fraction variance and its dissipation rate initially grow and then begin to decrease as mixing progresses and reduces density fluctuations. All terms in the transport equations generally grow or decay, with no qualitative change in their profile, except for the pressure flux contribution to the total turbulent kinetic energy flux, which changes sign early in time (a countergradient effect). The production-to-dissipation ratios corresponding to the turbulent kinetic energy and heavy-fluid mass fraction variance are large and vary strongly at small evolution times, decrease with time, and nearly asymptote as the flow enters a self-similar regime. The late-time turbulent kinetic energy production-to-dissipation ratio is larger than observed in shear-driven turbulent flows. The order of magnitude estimates of the terms in the transport equations are shown to be consistent with the DNS at late-time, and also confirms both the dominant terms and their evolutionary behavior. These results are useful for identifying the dynamically important terms requiring closure, and assessing the accuracy of the predictions of Reynolds-averaged Navier-Stokes and large-eddy simulation models of turbulent transport and mixing in transitional Rayleigh-Taylor instability-generated flow.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Schilling, Oleg; Mueschke, Nicholas J.
2010-10-18
Data from a 1152X760X1280 direct numerical simulation (DNS) of a transitional Rayleigh-Taylor mixing layer modeled after a small Atwood number water channel experiment is used to comprehensively investigate the structure of mean and turbulent transport and mixing. The simulation had physical parameters and initial conditions approximating those in the experiment. The budgets of the mean vertical momentum, heavy-fluid mass fraction, turbulent kinetic energy, turbulent kinetic energy dissipation rate, heavy-fluid mass fraction variance, and heavy-fluid mass fraction variance dissipation rate equations are constructed using Reynolds averaging applied to the DNS data. The relative importance of mean and turbulent production, turbulent dissipationmore »and destruction, and turbulent transport are investigated as a function of Reynolds number and across the mixing layer to provide insight into the flow dynamics not presently available from experiments. The analysis of the budgets supports the assumption for small Atwood number, Rayleigh/Taylor driven flows that the principal transport mechanisms are buoyancy production, turbulent production, turbulent dissipation, and turbulent diffusion (shear and mean field production are negligible). As the Reynolds number increases, the turbulent production in the turbulent kinetic energy dissipation rate equation becomes the dominant production term, while the buoyancy production plateaus. Distinctions between momentum and scalar transport are also noted, where the turbulent kinetic energy and its dissipation rate both grow in time and are peaked near the center plane of the mixing layer, while the heavy-fluid mass fraction variance and its dissipation rate initially grow and then begin to decrease as mixing progresses and reduces density fluctuations. All terms in the transport equations generally grow or decay, with no qualitative change in their profile, except for the pressure flux contribution to the total turbulent kinetic energy flux, which changes sign early in time (a countergradient effect). The production-to-dissipation ratios corresponding to the turbulent kinetic energy and heavy-fluid mass fraction variance are large and vary strongly at small evolution times, decrease with time, and nearly asymptote as the flow enters a self-similar regime. The late-time turbulent kinetic energy production-to-dissipation ratio is larger than observed in shear-driven turbulent flows. The order of magnitude estimates of the terms in the transport equations are shown to be consistent with the DNS at late-time, and also confirms both the dominant terms and their evolutionary behavior. Thus, these results are useful for identifying the dynamically important terms requiring closure, and assessing the accuracy of the predictions of Reynolds-averaged Navier-Stokes and large-eddy simulation models of turbulent transport and mixing in transitional Rayleigh-Taylor instability-generated flow.« less
Mohaghegh, Shahab
capability of being able to replicate the pressure and saturation distribution throughout the reservoirSPE 153844 Grid-Based Surrogate Reservoir Modeling (SRM) for Fast Track Analysis of Numerical Reservoir Simulation Models at the Grid block Level Shahab D. Mohaghegh, West Virginia University
Bell, John B.
the interaction of a laminar flame with decaying isotropic turbulence. Early studies of this type using single, and assume a mixture model for species diffusion. The single-grid scheme that forms the basis for ourNumerical Simulation of Premixed Turbulent Methane Combustion J. B. Bell, M. S. Day, A. S. Almgren
Michael Boyle; Alessandra Buonanno; Lawrence E. Kidder; Abdul H. Mroué; Yi Pan; Harald P. Pfeiffer; Mark A. Scheel
2008-10-06
Expressions for the gravitational wave (GW) energy flux and center-of-mass energy of a compact binary are integral building blocks of post-Newtonian (PN) waveforms. In this paper, we compute the GW energy flux and GW frequency derivative from a highly accurate numerical simulation of an equal-mass, non-spinning black hole binary. We also estimate the (derivative of the) center-of-mass energy from the simulation by assuming energy balance. We compare these quantities with the predictions of various PN approximants (adiabatic Taylor and Pade models; non-adiabatic effective-one-body (EOB) models). We find that Pade summation of the energy flux does not accelerate the convergence of the flux series; nevertheless, the Pade flux is markedly closer to the numerical result for the whole range of the simulation (about 30 GW cycles). Taylor and Pade models overestimate the increase in flux and frequency derivative close to merger, whereas EOB models reproduce more faithfully the shape of and are closer to the numerical flux, frequency derivative and derivative of energy. We also compare the GW phase of the numerical simulation with Pade and EOB models. Matching numerical and untuned 3.5 PN order waveforms, we find that the phase difference accumulated until $M \\omega = 0.1$ is -0.12 radians for Pade approximants, and 0.50 (0.45) radians for an EOB approximant with Keplerian (non-Keplerian) flux. We fit free parameters within the EOB models to minimize the phase difference, and confirm degeneracies among these parameters. By tuning pseudo 4PN order coefficients in the radial potential or in the flux, or, if present, the location of the pole in the flux, we find that the accumulated phase difference can be reduced - if desired - to much less than the estimated numerical phase error (0.02 radians).
Rosenberg, Duane L; Pouquet, Dr. Annick; Mininni, Dr. Pablo D.; Marino, Dr. Raffaele
2015-01-01
We report results on rotating stratified turbulence in the absence of forcing, with large-scale isotropic initial conditions, using direct numerical simulations computed on grids of up to $4096^3$ points. The Reynolds and Froude numbers are respectively equal to $Re=5.4\\times 10^4$ and $Fr=0.0242$. The ratio of the Brunt-V\\"ais\\"al\\"a to the inertial wave frequency, $N/f$, is taken to be equal to 5, a choice appropriate to model the dynamics of the southern abyssal ocean at mid latitudes. This gives a global buoyancy Reynolds number $R_B=ReFr^2=32$, a value sufficient for some isotropy to be recovered in the small scales beyond the Ozmidov scale, but still moderate enough that the intermediate scales where waves are prevalent are well resolved. We concentrate on the large-scale dynamics and confirm that the Froude number based on a typical vertical length scale is of order unity, with strong gradients in the vertical. Two characteristic scales emerge from this computation, and are identified from sharp variations in the spectral distribution of either total energy or helicity. A spectral break is also observed at a scale at which the partition of energy between the kinetic and potential modes changes abruptly, and beyond which a Kolmogorov-like spectrum recovers. Large slanted layers are ubiquitous in the flow in the velocity and temperature fields, and a large-scale enhancement of energy is also observed, directly attributable to the effect of rotation.
Oldenburg, C.M.
2013-01-01
for estimates of the oil and gas flow rate from the Macondoteam and carried out oil and gas flow simulations using theoil-gas system. The flow of oil and gas was simulated using
Torres-Verdín, Carlos
of simulation of electromagnetic borehole resistivity measurements for the assessment of rock formation self-adaptive method. The resulting grid enables fast simulations (few seconds per logging position of 3D simulators of resistivity log- ging measurements have been developed within the oil industry
Chen, Jacqueline H.; Hawkes, Evatt R.
2004-08-01
Direct numerical simulation (DNS) with complex chemistry was used to study statistics of displacement and consumption speeds in turbulent lean premixed methane-air flames. The main focus of the study is an evaluation of the extent to which a turbulent flame in the thin reaction zones regime can be described by an ensemble of strained laminar flames. Conditional averages with respect to strain for displacement and consumption speeds are presented over a wide range of strain typically encountered in a turbulent flame, compared with previous studies that either made local pointwise comparisons or conditioned the data on small strain and curvature. The conditional averages for positive strains are compared with calculated data from two different canonical strained laminar configurations to determine which is the optimal representation of a laminar flame structure embedded in a turbulent flame: the reactant-to-product (R-to-P) configuration or the symmetric twin flame configuration. Displacement speed statistics are compared for the progress-variable isosurface of maximum reaction rate and an isosurface toward the fresh gases, which are relevant for both modeling and interpretation of experiment results. Displacement speeds in the inner reaction layer are found to agree very well with the laminar R-to-P calculations over a wide range of strain for higher Damkhler number conditions, well beyond the regime in which agreement was expected. For lower Damkhler numbers, a reduced response to strain is observed, consistent with previous studies and theoretical expectations. Compared with the inner layer, broader and shifted probability density functions (PDFs) of displacement speed were observed in the fresh gases, and the agreement with the R-to-P calculations deteriorated. Consumption speeds show a poorer agreement with strained laminar calculations, which is attributed to multidimensional effects and a more attenuated unsteady response to strain fluctuations; however, they also show less departure from the unstrained laminar value, suggesting that detailed modeling of this quantity may not be critical for the conditions considered. For all quantities investigated, including CO production, the R-to-P laminar configuration provides an improved description relative to the twin flame configuration, which predicts qualitatively incorrect trends and overestimates extinction.
Auletta, C.; Raiconi, G.; De Luca, R.; Pace, S.
1995-05-01
We have performed numerical simulations of a field-cooled dc susceptibility experiment carried out for granular superconductors by modeling these systems with a simple Josephson-junction array proposed by the authors. By this analysis the temperature dependence of the positive field-cooled susceptibility at very low values of the applied magnetic field, observed by Braunisch {ital et} {ital al}. [Phys. Rev. Lett. 68, 1908 (1992)] for some ceramic superonductors, has been reproduced and interpreted.
Towards Real Earth Models --Computational Geophysics on Unstructured Tetrahedral Meshes?
Farquharson, Colin G.
Towards Real Earth Models -- Computational Geophysics on Unstructured Tetrahedral Meshes? Colin tetrahedral meshes. EM geophysics on unstructured tetrahedral meshes. Disadvantages, difficulties, challenges. Conclusions. #12;Outline: Geological models! Advantages of unstructured tetrahedral meshes. EM geophysics
Tavassoli, Armin
1999-01-01
The 2-dimensional, viscous and incompressible flow past a circular cylinder is investigated by solving the Navier-stokes equation. solved using CFD (Computational Fluid These equations are numerically Dynamics) methods on ...
Phung, Anh Ngoc
1995-01-01
, bristle diameter, bristle free length, seal backplate diameter, and lift-off gap. Numerical flow visualization illustrates the three-dimensional flow field, showing the circumferential, axial, and radial components of velocity near the bristle surface...
Boppa, Praneetha
2012-10-19
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...
Salpeter, Nathaniel
2012-07-16
This work focuses on both high fidelity experimental and numerical thermal hydraulic studies and advanced frequency decomposition methods. The major contribution of this work is a proposed method for spatio-temporal decomposition of frequencies...
Daniel A. Hemberger; Geoffrey Lovelace; Thomas J. Loredo; Lawrence E. Kidder; Mark A. Scheel; Béla Szilágyi; Nicholas W. Taylor; Saul A. Teukolsky
2013-09-23
The behavior of merging black holes (including the emitted gravitational waves and the properties of the remnant) can currently be computed only by numerical simulations. This paper introduces ten numerical relativity simulations of binary black holes with equal masses and equal spins aligned or anti-aligned with the orbital angular momentum. The initial spin magnitudes have $|\\chi_i| \\lesssim 0.95$ and are more concentrated in the aligned direction because of the greater astrophysical interest of this case. We combine this data with five previously reported simulations of the same configuration, but with different spin magnitudes, including the highest spin simulated to date, $\\chi_i \\approx 0.97$. This data set is sufficiently accurate to enable us to offer improved analytic fitting formulae for the final spin and for the energy radiated by gravitational waves as a function of initial spin. The improved fitting formulae can help to improve our understanding of the properties of binary black hole merger remnants and can be used to enhance future approximate waveforms for gravitational wave searches, such as Effective-One-Body waveforms.
Gedney, S.D.
1987-09-01
The electromagnetic pulse (EMP) produced by a high-altitude nuclear blast presents a severe threat to electronic systems due to its extreme characteristics. To test the vulnerability of large systems, such as airplanes, missiles, or satellites, they must be subjected to a simulated EMP environment. One type of simulator that has been used to approximate the EMP environment is the Large Parallel-Plate Bounded-Wave Simulator. It is a guided-wave simulator which has properties of a transmission line and supports a single TEM model at sufficiently low frequencies. This type of simulator consists of finite-width parallel-plate waveguides, which are excited by a wave launcher and terminated by a wave receptor. This study addresses the field distribution within a finite-width parallel-plate waveguide that is matched to a conical tapered waveguide at either end. Characteristics of a parallel-plate bounded-wave EMP simulator were developed using scattering theory, thin-wire mesh approximation of the conducting surfaces, and the Numerical Electronics Code (NEC). Background is provided for readers to use the NEC as a tool in solving thin-wire scattering problems.
Skibinski, Jakub; Wejrzanowski, Tomasz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02507 Warsaw (Poland); Caban, Piotr [Institute of Electronic Materials Technology, Wolczynska 133, 01919 Warsaw (Poland); Kurzydlowski, Krzysztof J. [Warsaw University of Technology, Faculty of Materials Science and Engineering Woloska, 141, 02507 Warsaw (Poland)
2014-10-06
In the present study numerical simulations of epitaxial growth of gallium nitride in Metal Organic Vapor Phase Epitaxy reactor AIX-200/4RF-S is addressed. Epitaxial growth means crystal growth that progresses while inheriting the laminar structure and the orientation of substrate crystals. One of the technological problems is to obtain homogeneous growth rate over the main deposit area. Since there are many agents influencing reaction on crystal area such as temperature, pressure, gas flow or reactor geometry, it is difficult to design optimal process. According to the fact that it's impossible to determine experimentally the exact distribution of heat and mass transfer inside the reactor during crystal growth, modeling is the only solution to understand the process precisely. Numerical simulations allow to understand the epitaxial process by calculation of heat and mass transfer distribution during growth of gallium nitride. Including chemical reactions in numerical model allows to calculate the growth rate of the substrate and estimate the optimal process conditions for obtaining the most homogeneous product.
Rasool, Syed Ahmed
1994-01-01
A vast amount of research has been conducted on the subject of pressure drop in muldphase flow systems. The simulator developed for this research incorporates the Beggs and Brill model for pressure drop prediction with an ...
Archibald, Richard Andrew
2009-01-01
We present the results of fully three dimensional, post-Newtonian hydrodynamical simulations of the dynamical evolution of mergers between compact stellar remnants (neutron stars and black holes). Although the code is ...
Oldenburg, C.M.
2013-01-01
for estimates of the oil and gas flow rate from the Macondooil-gas system. The flow of oil and gas was simulated usingmaximal flow rates of oil and gas. With the conceptual model
Zhu, Chen
drainage, potential radionuclide migration in fouled waste repositories, metal contaminant transport scale a radioactive waste, commonly called Naturally Occurring Radioactive Material (NORM) or technology Simulations of Reactions and Mass Transport CHEN ZHU* Department of Geological Sciences, Indiana University
Baudouin, Lucie
A controlled distributed parameter model for a fluid-flexible structure system: numerical consider the problem of active reduction of vibrations in a fluid-flexible structure system and the sloshing of the fuel inside the wing's tank. The control is performed using piezoelectric patches
Matteo Viel; Martin G. Haehnelt; Volker Springel
2006-04-20
We implement the hydro-PM (HPM) technique (Gnedin & Hui 1998) in the hydrodynamical simulation code GADGET-II and quantify the differences between this approximate method and full hydrodynamical simulations of the Lyman-alpha forest in a concordance LCDM model. At redshifts z=3 and z=4, the differences between the gas and dark matter (DM) distributions, as measured by the one-point distribution of density fluctuations, the density power spectrum and the flux power spectrum, systematically decrease with increasing resolution of the HPM simulqation. However, reducing these differences to less than a few percent requires a significantly larger number of grid-cells than particles, with a correspondingly larger demand for memory. Significant differences in the flux decrement distribution remain even for very high resolution hydro-PM simulations, particularly at low redshift. At z=2, the differences between the flux power spectra obtained from HPM simulations and full hydrodynamical simulations are generally large and of the order of 20-30 %, and do not decrease with increasing resolution of the HPM simulation. This is due to the presence of large amounts of shock-heated gas, a situation which is not adequately modelled by the HPM approximation. We confirm the results of Gnedin & Hui (1998) that the statistical properties of the flux distribution are discrepant by > 5-20 % when compared to full hydrodynamical simulations. The discrepancies in the flux power spectrum are strongly scale- and redshift-dependent and extend to large scales. Considerable caution is needed in attempts to use calibrated HPM simulations for quantitative predictions of the flux power spectrum and other statistical properties of the Lyman-alpha forest.
Martin, V.; Egido, J.L.; Khoo, T.L.; Lauritsen, T.
1995-06-01
The electromagnetic decay of the nuclei {sup 152,154,156}Dy is analyzed using microscopic Hartree-Fock calculations at finite temperature. The theoretical collective transition probabilities are implemented in numerical simulations to produce theoretical spectra. Thermal shape fluctuations are also taken into account. The inclusion of these correlation is crucial in order to understand the main features of the collective {ital E}2 spectra of these isotopes at different energies. The theoretical calculations suggest a shape change as responsible for the unusual features of the spectrum of the nucleus {sup 154}Dy at high energy.
Kusmierczyk, P; Wrobel, M
2012-01-01
The problem of hydraulic fracture for the PKN model is considered within the framework of approach presented recently by Linkov (2011). The modified formulation is further enhanced by employing an improved regularized boundary condition near the crack tip. This increases solution accuracy especially for singular leak-off regimes. A new dependent variable having clear physical sense is introduced. A comprehensive analysis of numerical algorithms based on various dependent variables is provided.
Koldanov, V. A.; Korobkov, S. V.; Gushchin, M. E.; Kostrov, A. V. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)
2011-08-15
The electromagnetic fields excited by circular loop antennas in a magnetized plasma in the whistler frequency range are simulated by the finite-difference time-domain method. The spatial structure of quasi-monochromatic fields excited in the near- and far-field zones by an antenna with a harmonic current, as well as the dynamics of the electromagnetic field excited by an antenna with a current in the form of a single video pulse, is studied. Simulations performed for a uniform plasma and uniform ambient magnetic field agree well with the results of theoretical analysis and model laboratory experiments performed on large-scale plasma devices.
Numerical Simulations of Violent Free Surface by a Coupled Level-Set and Volume-of-Fluid Method
Zhao, Yucheng
2014-04-18
in conjunction with the Finite-Analytical Navier-Stokes (FANS) method for time-domain simulations of violent free surface flow problems. In this method, immiscible two-phase flow is modeled as a single continuum with variable fluid properties across...
Eindhoven, Technische Universiteit
of a piston, an aftercooler (AC), a regenerator, a cold heat exchanger (CHX), a tube, a hot heat exchanger ( numerical model has been introduced to study steady oscillatory heat and mass transfer in the tube section, numerical simulation, high resolution scheme 1 Introduction The pulse tube is a relatively new type
C. S. S. Brandao; J. C. N. de Araujo
2012-04-24
A way to probe alternative theories of gravitation is to study if they could account for the structures of the universe. We then modified the well-known Gadget-2 code to probe alternative theories of gravitation through galactic dynamics. As an application, we simulate the evolution of spiral galaxies to probe alternative theories of gravitation whose weak field limits have a Yukawa-like gravitational potential. These simulations show that galactic dynamics can be used to constrain the parameters associated with alternative theories of gravitation. It is worth stressing that the recipe given in the present study can be applied to any other alternative theory of gravitation in which the superposition principle is valid.
Brandao, C. S. S.; De Araujo, J. C. N., E-mail: claudiosoriano.uesc@gmail.com, E-mail: jcarlos.dearaujo@inpe.br [Divisao de Astrofisica, Instituto Nacional de Pesquisas Espaciais, S. J. Campos, SP 12227-010 (Brazil)
2012-05-01
A way to probe alternative theories of gravitation is to study if they could account for the structures of the universe. We therefore modified the well-known Gadget-2 code to probe alternative theories of gravitation through galactic dynamics. As an application, we simulate the evolution of spiral galaxies to probe alternative theories of gravitation whose weak field limits have a Yukawa-like gravitational potential. These simulations show that galactic dynamics can be used to constrain the parameters associated with alternative theories of gravitation. It is worth stressing that the recipe given in this study can be applied to any other alternative theory of gravitation in which the superposition principle is valid.
Previtali, V.; Stancari, G.; Valishev, A.; /Fermilab; Shatilov, D.N.; /Novosibirsk, IYF
2012-05-01
Transverse beam diffusion for the Tevatron machine has been calculated using the Lifetrac code. The following effects were included: random noise (representing residual gas scattering, voltage noise in the accelerating cavities) lattice nonlinearities and beam-beam interactions. The time evolution of particle distributions with different initial amplitudes in Hamiltonian action has been simulated for 6 million turns, corresponding to a time of about 2 minutes. For each particle distribution, several cases have been considered: a single beam in storage ring mode, the collider case and the effects of a hollow electron beam collimator. The diffusion coefficient for some representative points in the amplitude space has been calculated by fitting the time evolution of delta-like particle distributions using the diffusion equation, for different machine conditions. The results confirm a strong efficiency of the electron lens as an halo diffusive enhancer, leading to diffusion coefficients which are at least a factor 10K higher than the values obtained for the collision case. This result is confirmed by the Frequency Map Analysis, which shows a clear intensification of resonance lines for particle amplitudes larger than the electron lens inner radius. If compared with past experiments, the simulations successfully reproduce the diffusion coefficients for the beam core, but still present a large discrepancy for halo particles, still under investigation.
Spiga, D; Pareschi, G
2015-01-01
Future X-ray telescopes like SIMBOL-X will operate in a wide band of the X-ray spectrum (from 0.1 to 80 keV); these telescopes will extend the optical performances of the existing soft X-ray telescopes to the hard X-ray band, and in particular they will be characterized by a angular resolution (conveniently expressed in terms of HEW, Half-Energy- Width) less than 20 arcsec. However, it is well known that the microroughness of the reflecting surfaces of the optics causes the scattering of X-rays. As a consequence, the imaging quality can be severely degraded. Moreover, the X-ray scattering can be the dominant problem in hard X-rays because its relevance is an increasing function of the photon energy. In this work we consistently apply a numerical method and an analytical one to evaluate the X-ray scattering impact on the HEW of an X-ray optic, as a function of the photon energy: both methods can also include the effects of figure errors in determining the final HEW. A comparison of the results obtained with th...
Oudini, N.; Taccogna, F.; Aanesland, A.
2014-06-15
Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of ??=?1, with a parametric study for ? up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.
Ewing, Richard E.
and Information Volume 1, Number 1, Pages 116 HIGH PERFORMANCE COMPUTING IN PETROLEUM APPLICATIONS RICHARD E in petroleum applications is to try to optimize the recovery of hydrocarbon from permeable underground the complex geomechanical, physical, and multiphase fluid flow processes that accompany the various recov- ery
Pruess, K.; Nordbotten, J.
2010-12-28
We have used the TOUGH2-MP/ECO2N code to perform numerical simulation studies of the long-term behavior of CO{sub 2} stored in an aquifer with a sloping caprock. This problem is of great practical interest, and is very challenging due to the importance of multi-scale processes. We find that the mechanism of plume advance is different from what is seen in a forced immiscible displacement, such as gas injection into a water-saturated medium. Instead of pushing the water forward, the plume advances because the vertical pressure gradients within the plume are smaller than hydrostatic, causing the groundwater column to collapse ahead of the plume tip. Increased resistance to vertical flow of aqueous phase in anisotropic media leads to reduced speed of updip plume advancement. Vertical equilibrium models that ignore effects of vertical flow will overpredict the speed of plume advancement. The CO{sub 2} plume becomes thinner as it advances, yet the speed of advancement remains constant over the entire simulation period of up to 400 years, with migration distances of more than 80 km. Our simulations include dissolution of CO{sub 2} into the aqueous phase and associated density increase, and molecular diffusion. However, no convection develops in the aqueous phase because it is suppressed by the relatively coarse (sub-) horizontal gridding required in a regional-scale model. A first crude sub-grid-scale model was developed to represent convective enhancement of CO{sub 2} dissolution. This process is found to greatly reduce the thickness of the CO{sub 2} plume, but, for the parameters used in our simulations, does not affect the speed of plume advancement.
Gokaltun, Seckin; Munroe, Norman; Subramaniam, Shankar
2014-12-31
This study presents a new drag model, based on the cohesive inter-particle forces, implemented in the MFIX code. This new drag model combines an existing standard model in MFIX with a particle-based drag model based on a switching principle. Switches between the models in the computational domain occur where strong particle-to-particle cohesion potential is detected. Three versions of the new model were obtained by using one standard drag model in each version. Later, performance of each version was compared against available experimental data for a fluidized bed, published in the literature and used extensively by other researchers for validation purposes. In our analysis of the results, we first observed that standard models used in this research were incapable of producing closely matching results. Then, we showed for a simple case that a threshold is needed to be set on the solid volume fraction. This modification was applied to avoid non-physical results for the clustering predictions, when governing equation of the solid granular temperate was solved. Later, we used our hybrid technique and observed the capability of our approach in improving the numerical results significantly; however, improvement of the results depended on the threshold of the cohesive index, which was used in the switching procedure. Our results showed that small values of the threshold for the cohesive index could result in significant reduction of the computational error for all the versions of the proposed drag model. In addition, we redesigned an existing circulating fluidized bed (CFB) test facility in order to create validation cases for clustering regime of Geldart A type particles.
Cartier-Michaud, T; Sarazin, Y; Abiteboul, J; Bufferand, H; Dif-Pradalier, G; Garbet, X; Grandgirard, V; Latu, G; Norscini, C; Passeron, C; Tamain, P
2015-01-01
The Projection on Proper elements (PoPe) is a novel method of code control dedicated to 1) checking the correct implementation of models, 2) determining the convergence of numerical methods and 3) characterizing the residual errors of any given solution at very low cost. The basic idea is to establish a bijection between a simulation and a set of equations that generate it. Recovering equations is direct and relies on a statistical measure of the weight of the various operators. This method can be used in any dimensions and any regime, including chaotic ones. This method also provides a procedure to design reduced models and quantify the ratio costs to benefits. PoPe is applied to a kinetic and a fluid code of plasma turbulence.
The Burn-UD code for the numerical simulations of the Hadronic-to-Quark-Matter phase transition
Ouyed, Amir; Koning, Nico; Ouyed, Rachid
2015-01-01
Burn-UD is a hydrodynamic combustion code used to model the phase transition of hadronic to quark matter with particular application to the interior of neutron stars. Burn-UD models the flame micro-physics for different equations of state (EoS) on both sides of the interface, i.e. for both the ash (up-down-strange quark phase) and the fuel (up-down quark phase). It also allows the user to explore strange quark seeding produced by different processes including DM annihilation inside neutron stars. The simulations provide a physical window to diagnose whether the combustion process will simmer quietly and slowly, lead to a transition from deflagration to detonation or a (quark) core-collapse explosion. Such an energetic phase transition (a Quark-Nova) would have consequences in high-energy astrophysics and could aid in our understanding of many still enigmatic astrophysical transients. Furthermore, having a precise understanding of the phase transition dynamics for different EoSs could aid further in constraini...
Developments in Petroleum Science, 6 FUNDAMENTALS OF NUMERICAL
Santos, Juan
Developments in Petroleum Science, 6 FUNDAMENTALS OF NUMERICAL RESERVOIR SIMULATION DONALD WCongressCatalogingin PublicationData Peaceman, Donald W Fundamentals of numerical reservoir simulation. (develrpents in petroleum
Leonid M. Ozernoy; Nick N. Gorkavyi; Tanya Taidakova
2000-01-18
Using numerical simulations, we examine the structure of a cometary population near a massive planet, such as a giant planet of the Solar system, starting with one-planet approximation (the Sun plus one planet). By studying the distributions of comets in semimajor axis, eccentricity, pericenter, and apocenter distances, we have revealed several interesting features in these distributions. The most remarkable ones include (i) spatial accumulation of comets near the planetary orbit (which we call the `cometary belt') and (ii) avoidance of resonant orbits by comets. Then we abandon one-planet approximation and examine as to how a cometary belt is modified when the influence of all four giant planets is taken into consideration. To this end, we simulate a stationary distribution of comets, which results from the gravitational scattering of the Kuiper belt objects on the four giant planets and accounts for the effects of mean motion resonances. Accounting for the influence of four giant planets makes the cometary belts overlapping, but nevertheless keeping almost all their basic features found in one-planet approximation. In particular, the belts maintain the gaps in the (a,e)- and (a,i)-space similar to the Kirkwood gaps in the main asteroid belt. We conclude that the large-scale structure of the Solar system is featured by the four cometary belts expected to contain 20-30 millions of scattered comets, and only a tiny fraction of them is currently visible as Jupiter-, Saturn-, etc. family comets.
NUMERICAL SIMULATION OF VORTEX BREAKDOWN
Prete, Vincenza Del
2011-01-01
irrotational vortex. NRC Con. Aero Rep. LR-378. Hald, O. &vortex breakdown" phenomenon. Aero Dept. , Imperial ColI.
NUMERICAL SIMULATION OF VORTEX BREAKDOWN
Prete, Vincenza Del
2011-01-01
axis of the tube and is called the vortex core. The basicthe tube plus a perturbation caused by the vortex breakdown.of the tube. Thus the occurrence of the vortex breakdown
Numerical Simulations of Bouncing Jets
Lee, Sanghyun
2014-07-18
The Kaye effect is a fascinating phenomenon of a leaping shampoo stream which was first described by Alan Kaye in 1963 as a property of non-Newtonian fluid. It manifest itself when a thin stream of non-Newtonian fluid is poured into a dish of fluid...
Sandia Energy - Direct Numerical Simulation
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; Johnson, Jeffrey N.
2015-04-18
Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on twomore »general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.« less
Vijaykumar, Anand
2011-02-22
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 ...
Bell, John B.
and Dufour effects, and radiative heat transfer, and assume a mixture-averaged model for differential species methods, low Mach number flows Turbulent premixed combustion is a major active research topic without introducing models for turbulence or turbulence chemistry interaction. We outline the numerical
Modeling-Computer Simulations At Akutan Fumaroles Area (Kolker, Et Al.,
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Modeling-Computer Simulations At Central Nevada Seismic Zone Region (Biasi,
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Modeling-Computer Simulations At Chocolate Mountains Area (Alm, Et Al.,
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Modeling-Computer Simulations At Coso Geothermal Area (1999) | Open Energy
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Modeling-Computer Simulations At Dixie Valley Geothermal Area (Kennedy &
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Modeling-Computer Simulations At Dixie Valley Geothermal Area (Wisian &
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Modeling-Computer Simulations At Fenton Hill HDR Geothermal Area (Brown &
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Modeling-Computer Simulations At Fenton Hill HDR Geothermal Area (Goff &
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Modeling-Computer Simulations At Fish Lake Valley Area (Deymonaz, Et Al.,
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Modeling-Computer Simulations At Hawthorne Area (Lazaro, Et Al., 2010) |
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Modeling-Computer Simulations At Kilauea East Rift Geothermal Area (Rudman
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Modeling-Computer Simulations At Nevada Test And Training Range Area
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Modeling-Computer Simulations At Northern Basin & Range Region (Biasi, Et
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Modeling-Computer Simulations At Northern Basin & Range Region (Blackwell,
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Modeling-Computer Simulations At Northern Basin & Range Region (Pritchett,
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Modeling-Computer Simulations At Nw Basin & Range Region (Biasi, Et Al.,
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Modeling-Computer Simulations At Nw Basin & Range Region (Blackwell, Et
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Modeling-Computer Simulations At Nw Basin & Range Region (Pritchett, 2004)
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Modeling-Computer Simulations At Obsidian Cliff Area (Hulen, Et Al., 2003)
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Modeling-Computer Simulations At Raft River Geothermal Area (1983) | Open
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Modeling-Computer Simulations At Stillwater Area (Wisian & Blackwell, 2004)
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Modeling-Computer Simulations At The Needles Area (Bell & Ramelli, 2009) |
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Modeling-Computer Simulations At U.S. West Region (Laney, 2005) | Open
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Modeling-Computer Simulations At U.S. West Region (Sabin, Et Al., 2004) |
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Modeling-Computer Simulations At U.S. West Region (Williams & Deangelo,
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Modeling-Computer Simulations At Walker-Lane Transitional Zone Region
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Modeling-Computer Simulations At Walker-Lane Transitional Zone Region
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Modeling-Computer Simulations At Walker-Lane Transitional Zone Region
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Modeling-Computer Simulations At White Mountains Area (Goff & Decker, 1983)
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Modeling-Computer Simulations At Coso Geothermal Area (1980) | Open Energy
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Modeling-Computer Simulations At Coso Geothermal Area (2000) | Open Energy
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Modeling-Computer Simulations At Cove Fort Area (Toksoz, Et Al, 2010) |
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Modeling-Computer Simulations At Desert Peak Area (Wisian & Blackwell,
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Modeling-Computer Simulations At Geysers Area (Goff & Decker, 1983) | Open
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Modeling-Computer Simulations At Raft River Geothermal Area (1977) | Open
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Modeling-Computer Simulations At Raft River Geothermal Area (1979) | Open
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Modeling-Computer Simulations At Raft River Geothermal Area (1980) | Open
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Modeling-Computer Simulations At San Juan Volcanic Field Area (Clarkson &
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Simulation 4, 239-250, 2003 Traffic Flow CA Model in Which Only the Cars Following the Trail of the Ahead Car from the NS model in that only the cars following the trail of the ahead car can be delayed. In other words, a car with spacing ahead longer than the car velocity limit M can not be delayed in the new model
Maruyama, Shigeo
with macrolayer model of Maruyama, we simulated the transient boiling curve for water and fluorinert FC-72(C6F14 boiling processes are very important in steel production and safety evaluations in nuclear reactors conduction within the heater. The transient boiling curves for water and FC-72 were predicted. The transient
Ng, Chung-Sang
8/26/10 10:33 AMAPS -52nd Annual Meeting of the APS Division of Plasma Physics - Eve...er Numerical/131043 Bulletin of the American Physical Society 52nd Annual Meeting of the APS Division of Plasma Physics - Eve...er Numerical Simulations of Coronal Heating: Reduced MHD via GPGPUs Page 2 of 2http://meetings.aps
Garcia, C. Amanda; Halford, Keith J.; Laczniak, Randell J.
2010-02-12
Hydraulic conductivities of volcanic and carbonate lithologic units at the Nevada Test Site were estimated from flow logs and aquifer-test data. Borehole flow and drawdown were integrated and interpreted using a radial, axisymmetric flow model, AnalyzeHOLE. This integrated approach is used because complex well completions and heterogeneous aquifers and confining units produce vertical flow in the annular space and aquifers adjacent to the wellbore. AnalyzeHOLE simulates vertical flow, in addition to horizontal flow, which accounts for converging flow toward screen ends and diverging flow toward transmissive intervals. Simulated aquifers and confining units uniformly are subdivided by depth into intervals in which the hydraulic conductivity is estimated with the Parameter ESTimation (PEST) software. Between 50 and 150 hydraulic-conductivity parameters were estimated by minimizing weighted differences between simulated and measured flow and drawdown. Transmissivity estimates from single-well or multiple-well aquifer tests were used to constrain estimates of hydraulic conductivity. The distribution of hydraulic conductivity within each lithology had a minimum variance because estimates were constrained with Tikhonov regularization. AnalyzeHOLE simulated hydraulic-conductivity estimates for lithologic units across screened and cased intervals are as much as 100 times less than those estimated using proportional flow-log analyses applied across screened intervals only. Smaller estimates of hydraulic conductivity for individual lithologic units are simulated because sections of the unit behind cased intervals of the wellbore are not assumed to be impermeable, and therefore, can contribute flow to the wellbore. Simulated hydraulic-conductivity estimates vary by more than three orders of magnitude across a lithologic unit, indicating a high degree of heterogeneity in volcanic and carbonate-rock units. The higher water transmitting potential of carbonate-rock units relative to volcanic-rock units is exemplified by the large difference in their estimated maximum hydraulic conductivity; 4,000 and 400 feet per day, respectively. Simulated minimum estimates of hydraulic conductivity are inexact and represent the lower detection limit of the method. Minimum thicknesses of lithologic intervals also were defined for comparing AnalyzeHOLE results to hydraulic properties in regional ground-water flow models.
Prokopidis, Konstantinos P
2013-01-01
A novel 3-D higher-order finite-difference time-domain framework with complex frequency-shifted perfectly matched layer for the modeling of wave propagation in cold plasma is presented. Second- and fourth-order spatial approximations are used to discretize Maxwell's curl equations and a uniaxial perfectly matched layer with the complex frequency-shifted equations is introduced to terminate the computational domain. A numerical dispersion study of second- and higher-order techniques is elaborated and their stability criteria are extracted for each scheme. Comparisons with analytical solutions verify the accuracy of the proposed methods and the low dispersion error of the higher-order schemes.
Grossman, A.; Errico, R.M.
1999-11-29
The vertical motion of constant density atmospheric balloons has been considered via an equation of motion for the vertical displacement of a balloon, due to vertical air motion, which can be numerically solved for balloon positions. Initial calculations are made for a constant density atmosphere. Various vertical wind models with relatively large amplitudes are applied to the model to determine how tightly the balloons are coupled to the reference level and the time scale for the balloons to change to the wind driven reference altitude. A surface launch of a balloon to a 6 km reference altitude is modeled using a detailed atmospheric pressure-density-temperature profile in the equation of motion. The results show the balloons to be relatively tightly coupled ({approx} 50-100 m) to the reference altitude.
Not Available
1989-11-01
The Department of Energy (DOE) is preparing an Environmental Impact Statement (EIS) as part of the process for continuing operation of three reactors at the Savannah River Site (SRS). As required by the National Environmental Policy Act (NEPA), the EIS must address the potential environmental consequences to human health and the environment of this major federal action.'' Some of the possible consequences are related to subsurface transport of radionuclides released to seepage basins during normal reactor operation. To assist in the evaluation of the potential subsurface environmental impacts of these releases, Camp Dresser McKee Inc. (CDM) was contracted in June of 1989 to develop a three-dimensional groundwater flow and contaminant transport model which will simulate the movement of radionuclides at each of the reactor areas after they enter the groundwater system through the seepage basins. This report describes the development, calibration, and simulation results of the groundwater flow and contaminant transport model developed for this task. 10 refs., 63 figs., 11 tabs.
Bianconi, Andrea
2014-01-01
Background: The epidemiology of the slightly radioactive contrast agent named Thorotrast presents a very long latency period between the injection and the development of the related pathologies. It is an example of the more general problem posed by a radioactive internal contaminant whose effects are not noteworthy in the short term but become dramatic in the long period. A point that is still to be explored is fluctuations (in space and time) in the localized absorption of radiation by the tissues. Methods: A Monte Carlo simulation code has been developed to study over a 30 year period the daily absorption of alpha radiation by micrometer sized portions of tissue placed at a distance of 0-100 micrometers from a model source, that approximates a compact thorium dioxide source in liver or spleen whose size is larger or equal to 20 micrometers. The biological depletion of the daughter nuclei of the thorium series is taken into account. The initial condition assumes chemically purified natural thorium. Results: ...
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Deiterding, Ralf
2011-01-01
Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniquesmore »in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.« less
Modeling Computational Security in Long-Lived Systems, Version 2 Ran Canetti1,2
International Association for Cryptologic Research (IACR)
Modeling Computational Security in Long-Lived Systems, Version 2 Ran Canetti1,2 , Ling Cheung2 Introduction Computational security in long-lived systems: Security properties of cryptographic protocols computational power. This type of security degrades progressively over the lifetime of a protocol. However, some
Modeling Computational Security in Long-Lived Systems Ran Canetti1,2
International Association for Cryptologic Research (IACR)
Modeling Computational Security in Long-Lived Systems Ran Canetti1,2 , Ling Cheung2 , Dilsun Kaynar Introduction Computational security in long-lived systems: Security properties of cryptographic protocols protocols, security relies on the assumption that adversarial entities have lim- ited computational power
Creative Commons Copyright 2013 Some Rights Reserved CMC: A Model Computer Science Curriculum
Iyer, Sridhar
for K-12 Schools 3rd Edition, Released June 2013 Technical Report: TR-CSE-2013-52 Department of Computer-12 Schools Creative Commons Copyright © 2013 Some Rights Reserved 2 CMC: A Model Computer Science Curriculum for K-12 Schools 3rd Edition June, 2013 Authors Sridhar Iyer*, Farida Khan, Sahana Murthy
Disruptive Innovation in Numerical Hydrodynamics
Waltz, Jacob I.
2012-09-06
We propose the research and development of a high-fidelity hydrodynamic algorithm for tetrahedral meshes that will lead to a disruptive innovation in the numerical modeling of Laboratory problems. Our proposed innovation has the potential to reduce turnaround time by orders of magnitude relative to Advanced Simulation and Computing (ASC) codes; reduce simulation setup costs by millions of dollars per year; and effectively leverage Graphics Processing Unit (GPU) and future Exascale computing hardware. If successful, this work will lead to a dramatic leap forward in the Laboratory's quest for a predictive simulation capability.
10.34 Numerical Methods Applied to Chemical Engineering, Fall 2001
Beers, Kenneth J.
Numerical methods for solving problems arising in heat and mass transfer, fluid mechanics, chemical reaction engineering, and molecular simulation. Topics: numerical linear algebra, solution of nonlinear algebraic equations ...
Numerical simulation of electrokinetically driven micro flows
Hahm, Jungyoon
2005-11-01
are systematically studied. As a first application, flow and species transport control in a grooved micro-channel using local electrokinetic forces are studied. Locally applied electric fields, zeta potential patterned grooved surfaces, and geometry are manipulated...
Methods for Numerical Flow Simulation Rolf Rannacher
models of laminar hemodynamical flows. We discuss space and time dis- cretization with emphasis as flow control and model calibration. We concen- trate on laminar flows in which all relevant spatial-Stokes equations The continuum mechanical model of the flow of a viscous Newtonian fluid is the system
NUMERICAL SIMULATION OF INCOMPRESSIBLE FLOWS IN ...
to transitions to turbulence in rotating flows and to design corresponding dynamic ..... but possess special structures such that the equation (c1B + c2D)x = f can.
Numerical simulation of undersea cable dynamics
Ablow, C.M.; Schechter, S.
1983-01-01
A fully three-dimensional code has been written to compute the motion of a towed cable. The code is based on a robust and stable finite difference approximation to the differential equations derived from basic dynamics. A 3500-ft cable pulled at 18.5 knots (hr/sup -1/) through a circular turn of 700 yd radius has been computed in about half of the real time of the maneuver. The computed displacements are close to the measured ones; the changes in depth are within 2%.
Numerical Simulations ANSYS FLUENT 14.0
partially contact end of cartridge due to machining variations, neutron-induced swelling, thermal expansion
Numerical Simulation of Pulse-Tube Refrigerators
Tijsseling, A.S.
. . . . . . . . . . . . . . . . . . 51 3.3.1 A model problem . . . . . . . . . . . . . . . . . 52 3.3.2 Two-grid LUGR with fixed refinement area . . . . . . . . 53 3.3.3 Two-grid LUGR with moving refinement area . . . . . . . 55 4 in fully developed pipe flow . . . . 76 5 Flow and heat transfer computations for the pulse tube 81 5.1 One
Direct Numerical Simulation of Cosmological Reionization /
So, Geoffrey C.
2013-01-01
hydrogen reionization. Shown are projections of density, radiation energy density,hydrogen reionization. Shown are projections of density, radiation energy density,
A numerical sensitivity analysis of streamline simulation
Chaban Habib, Fady Ruben
2005-02-17
.9.................................................................................................. 88 4.60 Homogeneous with qinj=50 Bbls/D varying SegIT value.............................. 89 4.61 Homogeneous line to line with qinj=50 Bbls/D using different ? t. ............... 90 4.62 Homogeneous line to block at same PVI using ? t=20... days........................... 92 4.63 Homogeneous line to block at same PVI using ? t=5 days............................. 93 4.64 PermX distribution for heterogeneous model in gravity cases....................... 94 4.65 Heterogeneous line...
Numerical Simulations of Protoplanetary Igor Novikov
Froebrich, Dirk
medium with the PPN stellar wind model. The properties of investigated post-AGB outflows are dependent Jørgensen, Javier Eguidazu, Joern Foertsch, Josh Cave, Merlin Urban, Myles O'Donoghue, Niklas Scholz, Rob Mc to mass loss in the form of high velocity, collimated winds which shock and shape the ejected shell
Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; Johnson, Jeffrey N.
2015-04-18
Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.
Souza, Paulo Victor Santos
2015-01-01
Flow of viscous fluids are not usually discussed in detail in general and basic courses of physics. This is due in part to the fact that the Navier-Stokes equation has analytical solution only for a few restricted cases, while more sophisticated problems can only be solved by numerical methods. In this text, we present a computer simulation of wind tunnel, i.e., we present a set of programs to solve the Navier-Stokes equation for an arbitrary object inserted in a wind tunnel. The tunnel enables us to visualize the formation of vortices behind object, the so-called von K\\'arm\\'an vortices, and calculate the drag force on the object. We believe that this numerical wind tunnel can support the teacher and allow a more elaborate discussion of viscous flow. The potential of the tunnel is exemplified by the study of the drag on a simplified model of wing whose angle of attack can be controlled. A link to download the programs that make up the tunnel appears at the end.
Toward portable programming of numerical linear algebra on manycore...
Office of Scientific and Technical Information (OSTI)
Resource Relation: Conference: Toward petaflop numerical simulation on parallel hybrid architectures held June 6-10, 2011 in Sophia Antipolis, France.; Related Information:...
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; Johnson, Jeffrey N.
2015-04-18
Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on twomore »general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.« less
Direct Numerical Simulation and Large Eddy Simulation of Compressible Turbulence
Erlebacher, Gordon
of attention in the fluid dynamics community, owing perhaps to, the renewed interest in the de sign,b) Unfortunately, it is unlikely that the near future will bring about experiments detailed enough to confirm and in the definition of kinetic energy add a degree of complexity to the interpre tation of intermodal energy
COMPARING SIMULATION METHODS FOR FIRE SPREADING ACROSS A FUEL BED
Wainer, Gabriel
choice to solve the problem. Diffusion processes (oil spills, fire spread, insect infestation, etcCOMPARING SIMULATION METHODS FOR FIRE SPREADING ACROSS A FUEL BED Alexandre Muzy Computer Modeling computer simulation of a semi-physical fire spread model. Forest fire is a com- plex phenomenon, which
A NUMERICAL STUDY OF A FULLY CONSERVATIVE METHOD FOR HYPERELASTICVISCOPLASTIC
New York at Stoney Brook, State University of
based on a new approach to the simulation of materials undergoing large de formation. Our numericalA NUMERICAL STUDY OF A FULLY CONSERVATIVE METHOD FOR HYPERELASTICVISCOPLASTIC MATERIALS XIAO LIN algorithm for the simulation of the impact of hyperelasticviscoplastic materials in two dimensions
Kaper, Tasso J. Kramer, Mark A.; Rotstein, Horacio G.
2013-12-15
Rhythmic neuronal oscillations across a broad range of frequencies, as well as spatiotemporal phenomena, such as waves and bumps, have been observed in various areas of the brain and proposed as critical to brain function. While there is a long and distinguished history of studying rhythms in nerve cells and neuronal networks in healthy organisms, the association and analysis of rhythms to diseases are more recent developments. Indeed, it is now thought that certain aspects of diseases of the nervous system, such as epilepsy, schizophrenia, Parkinson's, and sleep disorders, are associated with transitions or disruptions of neurological rhythms. This focus issue brings together articles presenting modeling, computational, analytical, and experimental perspectives about rhythms and dynamic transitions between them that are associated to various diseases.
Numerical Model Construction with Closed Observables
Felix Dietrich; Gerta Köster; Hans-Joachim Bungartz
2015-10-18
Performing analysis, optimization and control using simulations of many-particle systems is computationally demanding when no macroscopic model for the dynamics of the variables of interest is available. In case observations on the macroscopic scale can only be produced via legacy simulator code or live experiments, finding a model for these macroscopic variables is challenging. In this paper, we employ time-lagged embedding theory to construct macroscopic numerical models from output data of a black box, such as a simulator or live experiments. Since the state space variables of the constructed, coarse model are dynamically closed and observable by an observation function, we call these variables closed observables. The approach is an online-offline procedure, as model construction from observation data is performed offline and the new model can then be used in an online phase, independent of the original. We illustrate the theoretical findings with numerical models constructed from time series of a two-dimensional ordinary differential equation system, and from the density evolution of a transport-diffusion system. Applicability is demonstrated in a real-world example, where passengers leave a train and the macroscopic model for the density flow onto the platform is constructed with our approach. If only the macroscopic variables are of interest, simulation runtimes with the numerical model are three orders of magnitude lower compared to simulations with the original fine scale model. We conclude with a brief discussion of possibilities of numerical model construction in systematic upscaling, network optimization and uncertainty quantification.
142 Los Alamos Science Number 29 2005 Direct Numerical
Kurien, Susan
142 Los Alamos Science Number 29 2005 Direct Numerical Simulations of Turbulence Data Generation visualization tools. Los Alamos scientists have been able to simulate flows of Reynolds numbers up to 105 subdomain of the 20483 turbulence simulation performed on the ASC Q machine at Los Alamos. The ASC Q machine
The effect of shear on heat budgets in a simulated Mesoscale Convective System
Shaw, Justin David
2000-01-01
The evolution and structure of simulated Mesoscale Convective Systems (MCS) were examined using the Collaborative Model for Multiscale Atmospheric Simulations. Three numerical simulations were performed, with the amount ...
International Association for Cryptologic Research (IACR)
Modeling Computational Security in LongLived Systems # ## Ran Canetti 1,2 , Ling Cheung 2 , Dilsun Introduction Computational security in longlived systems: Security properties of cryptographic protocols computational power. This type of security degrades progressively over the lifetime of a protocol. However, some
High performance computing and numerical modelling
,
2014-01-01
Numerical methods play an ever more important role in astrophysics. This is especially true in theoretical works, but of course, even in purely observational projects, data analysis without massive use of computational methods has become unthinkable. The key utility of computer simulations comes from their ability to solve complex systems of equations that are either intractable with analytic techniques or only amenable to highly approximative treatments. Simulations are best viewed as a powerful complement to analytic reasoning, and as the method of choice to model systems that feature enormous physical complexity such as star formation in evolving galaxies, the topic of this 43rd Saas Fee Advanced Course. The organizers asked me to lecture about high performance computing and numerical modelling in this winter school, and to specifically cover the basics of numerically treating gravity and hydrodynamics in the context of galaxy evolution. This is still a vast field, and I necessarily had to select a subset ...
The NumLab Numerical Laboratory J. Maubach 1 and A. Telea 2
Eindhoven, Technische Universiteit
The NumLab Numerical Laboratory J. Maubach 1 and A. Telea 2 Department of Mathematics and Computer environments addresses numerical simulation, interac- tive visualisation and computational steering. Most- bling numerical simulations from computational and visualisation blocks, as well as building such blocks
Numerical study of high heat ux pool boiling heat transfer Ying He a,*, Masahiro Shoji b
Maruyama, Shigeo
Numerical study of high heat ¯ux pool boiling heat transfer Ying He a,*, Masahiro Shoji b , Shigeo simulation model of boiling heat transfer is proposed based on a numerical macrolayer model [S. Maruyama, M. Shoji, S. Shimizu, A numerical simulation of transition boiling heat transfer, in: Proceedings
Assessment of the MUSTA approach for numerical relativistic dynamics
Blakely, P. M.; Nikiforakis, N.; Henshaw, W. D.
2015-03-04
waves 1. Introduction The numerical solution of the relativistic hydrodynamical equa- tions is of importance to the simulation of astrophysical phe- nomena such as gamma-ray bursts, supernova core-collapse, and relativistic wind accretion. Although...
Numerical and Experimental Investigation of Tidal Current Energy Extraction
Sun, Xiaojing
2008-01-01
Numerical and experimental investigations of tidal current energy extraction have been conducted in this study. A laboratory-scale water flume was simulated using commercial computational fluid dynamics (CFD) code FLUENT. ...
An investigation of the numerical treatment of condensation
Sasson, Joseph
The simulation of complete condensation continues to challenge the numerical methods currently used for multi-phase flow modeling; especially at low pressures, the change of phase process from a two-phase mixture to liquid ...
Numerical Study of Abutment Scour in Cohesive Soils
Chen, Xingnian
2010-01-16
. Numerical simulations of overtopping flow in straight rectangular channel, straight compound channel and channel bend have been conducted. The bridge deck is found to be able to change the flow distribution and the bed shear stress will increase...
NUMERICAL ANALYSIS OF A FINITE ELEMENT SCHEME FOR THE APPROXIMATION OF HARMONIC MAPS INTO SURFACES
Bartels, Soeren
NUMERICAL ANALYSIS OF A FINITE ELEMENT SCHEME FOR THE APPROXIMATION OF HARMONIC MAPS INTO SURFACES Geometric partial differential equations and their analysis as well as numerical simulation have recently
Computation and Visualisation in the NumLab Numerical Laboratory
Telea, Alexandru C.
for the underlying mathematics. Assembling numerical simulations from computational and visualisation blocks, as wellComputation and Visualisation in the NumLab Numerical Laboratory J.M.L. Maubach1 and A.C. Telea1 Eindhoven University of Technology, Department of Mathematics and Computer Science, Postbox 513, NL-5600 MB
.g., water flooding, polymer flooding, thermal flooding, etc. To this end, accurate numerical simulation
RIGOROUS MODELING AND SIMULATION OF MECHATRONIC SYSTEMS
Taylor, James H.
RIGOROUS MODELING AND SIMULATION OF MECHATRONIC SYSTEMS James H. Taylor Professor Emeritus, Systems on mechatronic systems. Emphasis is placed on rigorous techniques and selecting the most appropriate method mentioned above for mechatronic systems. Key Words: Mechatronic systems, modeling, simulation, numerical
Introduction to exact numerical computation
Escardó, Martín
Introduction to exact numerical computation Notes 2 Floating-point computation 4 3 Exact numerical (called the operational semantics) for computing a syntactical representative of the mathematical entity
Numerical Investigation of turbulent coupling boundary layer of air-water interaction flow
Liu, Song, S.M. Massachusetts Institute of Technology
2005-01-01
Air-water interaction flow between two parallel flat plates, known as Couette flow, is simulated by direct numerical simulation. The two flowing fluids are coupled through continuity of velocity and shear stress condition ...
Numerical modeling of species transport in turbulent flow and experimental study on aerosol sampling
Vijayaraghavan, Vishnu Karthik
2007-04-25
Numerical simulations were performed to study the turbulent mixing of a scalar species in straight tube, single and double elbow flow configurations. Different Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation ...
Hamann, Bernd
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS Int. J. Numer. Anal geomechanics Boris Jeremi!cc1, *,y , Gerik Scheuermann2,3 , Jan Frey3 , Zhaohui Yang1 , Bernd Hamann2 , Kenneth is the visualization of stress tensors resulting from 3D numerical simulations in computational geomechanics
Acoustic Simulation COMP 768 Presentation
Lin, Ming C.
) · Variation of pressure governed by Helmholtz's Acoustic Wave Equation (a PDE) · Use a numerical method;Auralization 7[Funkhouser03] #12;Acoustic Phenomena · In reality, sound waves exhibit: Reflection (specular · Statistical Acoustics · Hybrid Acoustics 10 #12;Numerical Simulation · Sound modeled as pressure waves: P(x, t
Self-similar radiation from numerical Rosenau-Hyman compactons
Rus, Francisco Villatoro, Francisco R.
2007-11-10
The numerical simulation of compactons, solitary waves with compact support, is characterized by the presence of spurious phenomena, as numerically induced radiation, which is illustrated here using four numerical methods applied to the Rosenau-Hyman K(p, p) equation. Both forward and backward radiations are emitted from the compacton presenting a self-similar shape which has been illustrated graphically by the proper scaling. A grid refinement study shows that the amplitude of the radiations decreases as the grid size does, confirming its numerical origin. The front velocity and the amplitude of both radiations have been studied as a function of both the compacton and the numerical parameters. The amplitude of the radiations decreases exponentially in time, being characterized by a nearly constant scaling exponent. An ansatz for both the backward and forward radiations corresponding to a self-similar function characterized by the scaling exponent is suggested by the present numerical results.
Not Available
1992-12-01
The effort of the experimental group has been concentrated on the CERN ALEPH and FERMILAB D0 collider experiments and completion of two fixed target experiments. The BNL fixed target experiment 771 took the world`s largest sample of D(1285) and E/iota(1420) events, using pion, kaon and antiproton beams. Observing the following resonances: 0{sup {minus_plus}} [1280], 1{sup {plus}{plus}} [1280], 0{sup {minus_plus}} [1420], 0{sup {minus_plus}} [1470], 1{sup {plus_minus}} [1415]. The Fermilab fixed target experiment E711, dihadron production in pN interactions at 800 GeV, completed data reduction and analysis. The atomic weight dependence, when parameterized as {sigma}(A) = {sigma}{sub o}A{sup {alpha}}, yielded a value of {alpha} = 1.043 {plus_minus} 0.011 {plus_minus} .012. The cross section per nucleon and angular distributions was also measured as a function of two particle mass and agrees very well with QCD calculations. The D0 Fermilab Collider Experiment E740 began its first data taking run in April 1992. The CERN collider experiment ALEPH at LEP is presently taking more data. The Z mass and width, the couplings to the upper and lower components of the hadronic isospin doublet, forward-backward asymmetries of hadronic events, and measurements of the fragmentation process have been made. The effort of detector development for the SSC has substantially increased with particular emphasis on scintillators, both in fibers and plates. Work has continued on higher-order QCD calculations using the Monte Carlo technique developed previously. This year results for WW, ZZ, WZ, and {sub {gamma}{gamma}} production have been published. A method for incorporating parton showering in such calculations was developed and applied to W production. The multicanonical Monte Carlo algorithm has stood up to the promises anticipated; it was used in multicanonical simulations of first-order phase transitions and for spin glass systems.
An Interactive Course in Numerical Methods for the Earth Susan E. Allen
Stockie, John
are typically in physics, mathematics, chemistry, biology or geography, and exposure to numerical computing science are becoming more and more dependent on numerical simulation, modelling, and computationally courses in numerical methods using MatlabTM as the programming language, or a graduate-level mathematics
The phase diagram of QCD from lattice simulations Massimo D'Elia
Heller, Barbara
'Universit`a di Pisa and INFN - Sezione di Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy Numerical simulations
Lattice Boltzmann Model for Numerical Relativity
Ilseven, E
2015-01-01
In the Bona-Masso formulation, Einstein equations are written as a set of flux conservative first order hyperbolic equations that resemble fluid dynamics equations. Based on this formulation, we construct a lattice Boltzmann model for Numerical Relativity. Our model is validated with well-established tests, showing good agreement with analytical solutions. Furthermore, we show that by increasing the relaxation time, we gain stability at the cost of losing accuracy, and by decreasing the lattice spacings while keeping a constant numerical diffusivity, the accuracy and stability of our simulations improves. Finally, in order to show the potential of our approach a linear scaling law for parallelisation with respect to number of CPU cores is demonstrated. Our model represents the first step in using lattice kinetic theory to solve gravitational problems.
Grid-independent Issue in Numerical Heat Transfer
Yao Wei; Wang Jian; Liao Guangxuan
2006-09-26
Grid independent is associated with the accuracy or even rationality of numerical results. This paper takes two-dimensional steady heat transfer for example to reveal the effect of grid resolution on numerical results. The law of grid dependence is obtained and a simple mathematical formula is presented. The production acquired here can be used as the guidance in choosing grid density in numerical simulation and get exact grid independent value without using infinite fine grid. Through analyzing grid independent, we can find the minimum number of grid cells that is needed to get grid-independent results. Such strategy can save computational resource while ensure a rational computational result.
MESOSCALE SIMULATIONS OF POWDER COMPACTION
Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)
2009-12-28
Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.
Method for simulating discontinuous physical systems
Baty, Roy S. (Albuquerque, NM); Vaughn, Mark R. (Albuquerque, NM)
2001-01-01
The mathematical foundations of conventional numerical simulation of physical systems provide no consistent description of the behavior of such systems when subjected to discontinuous physical influences. As a result, the numerical simulation of such problems requires ad hoc encoding of specific experimental results in order to address the behavior of such discontinuous physical systems. In the present invention, these foundations are replaced by a new combination of generalized function theory and nonstandard analysis. The result is a class of new approaches to the numerical simulation of physical systems which allows the accurate and well-behaved simulation of discontinuous and other difficult physical systems, as well as simpler physical systems. Applications of this new class of numerical simulation techniques to process control, robotics, and apparatus design are outlined.
Fundamentals of plasma simulation
Forslund, D.W.
1985-01-01
With the increasing size and speed of modern computers, the incredibly complex nonlinear properties of plasmas in the laboratory and in space are being successfully explored in increasing depth. Of particular importance have been numerical simulation techniques involving finite size particles on a discrete mesh. After discussing the importance of this means of understanding a variety of nonlinear plasma phenomena, we describe the basic elements of particle-in-cell simulation and their limitations and advantages. The differencing techniques, stability and accuracy issues, data management and optimization issues are discussed by means of a simple example of a particle-in-cell code. Recent advances in simulation methods allowing large space and time scales to be treated with minimal sacrifice in physics are reviewed. Various examples of nonlinear processes successfully studied by plasma simulation will be given.
Numerical studies of galaxy formation using special purpose hardware
Matthias Steinmetz
2002-01-25
I review recent progress in numerically simulating the formation and evolution of galaxies in hierarchically clustering universes. Special emphasis is given to results based on high-resolution gas dynamical simulations using the N-body hardware integrator GRAPE. Applications address the origin of the spin of disk galaxies, the structure and kinematics of damped Lyman-alpha systems, and the origin of galaxy morphology and of galaxy scaling laws.
Numerical Simulations of Subsonic and Transonic Open-Cavity Flows
to Graduate Research Assistant, Department of Mechanical Engineering and Florida Center for Advanced Aero Center for Advanced Aero-Propulsion, agn13@my.fsu.edu. Assistant Professor, Department of Mechanical Engineering and Florida Center for Advanced Aero-Propulsion, ktaira@fsu.edu. §Eminent Scholar and Professor
Numerical Simulation of Shock-Dispersed Fuel Charges
Bell, John B.; Day, Marcus; Beckner, Vincent; Rendleman, Charles; Kuhl, Allen L.; Neuwald, P.
2005-01-01
SDF charge in which a 0.5 g PETN booster charge is used toproducts from the composite (PETN/TNT) charge in the 6.6 lbehavior of a composite TNT/PETN charge in a calorimeter.
Numerical simulation of granular flows Pierre A. Gremaud
in the Geosciences (Soil Mechanics). Mathematical model: The approach taken is that of Continuum Mechanics. The mechanical properties of the grains are described by a small number of assumptions and parameters. Friction
Direct numerical simulation of turbulent Taylor–Couette flow
2007-08-23
Brindley (1984) proposed a mathematical model by partitioning the flow into interior. (Taylor ... A comprehensive verification for several parameters was conducted, ... The cylinder axis is aligned with the z-axis of the coordinate system
Numerical Simulation of a Laboratory-Scale Turbulent Slot Flame
Bell, John B.
detailed chemical kinetics and a mixture model for differential species diffusion. Methane chemistry are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second
Turbulent Supersonic Channel Flow: Direct Numerical Simulation and Modeling
Heinz, Stefan
modeling: the turbulence frequency production mechanism, wall damping effects on turbulence model frequency production mechanisms and wall damping effects may be explained very well on the basis, Chik w = wall viscosity = kinematic viscosity, = T = turbulent kinematic viscosity, Ck d = pressure
Numerical simulation of laminar reacting flows with complex chemistry
Day, M.S.
2011-01-01
of two-dimensional axisymmetric laminar diff usion flames byof a confined axisymmetric laminar diffusion flame using aalgorithms for premixed laminar steady-state flames. Comb.
Numerical Simulations of Leakage from Underground LPG Storage Caverns
Yamamoto, Hajime; Pruess, Karsten
2004-01-01
U. Case History: Blowout at an LPG Storage Cavern in Sweden,and Heads at an Underground LPG Storage Cavern Site, Journalof Leakage from Underground LPG Storage Caverns Hajime