A simple approximate Riemann solver for hyperbolic systems of conservation laws is developed for its use in Godunov schemes. The solver is based on characteristic formulations and is illustrated through Euler and idea...
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A simple approximate Riemann solver for hyperbolic systems of conservation laws is developed for its use in Godunov schemes. The solver is based on characteristic formulations and is illustrated through Euler and ideal magnetohydrodynamical (MHD) equations. The procedure of a high-order Godunov scheme incorporated with the Riemann solver for one-dimensional hyperbolic systems of conservation laws is described in detail. The correctness of the scheme is shown by comparison with the piecewise parabolic method for Euler equations and by comparison with exact solutions of Riemann problems for ideal MHD equations. The robustness of the scheme is demonstrated through numerical examples involving more than one strong shock at the same time. It is shown that the scheme offers the principle advantages of Godunov schemes: robust operation in the presence of strong waves, thin shock fronts, thin contact and slip surface discontinuities. (C) 1995 Academic Press, Inc.
作者：
DAI, WLWOODWARD, PRSchool of Physics and Astronomy
Army High Performance Computing Research Center Supercomputer Institute University of Minnesota 1100 Washington Avenue South Minneapolis Minnesota 55415
In order to understand the interaction between solar wind irregularities and the closed magnetosphere, three‐dimensional (3‐D) computer simulations for ideal magnetohydrodynamical (MHD) equations are performed. This...
In order to understand the interaction between solar wind irregularities and the closed magnetosphere, three‐dimensional (3‐D) computer simulations for ideal magnetohydrodynamical (MHD) equations are performed. This paper considers only the situation in which the initial interstellar magnetic field is either parallel or antiparallel to the magnetospheric magnetic field. The irregularity is modeled as a ball, which initially moves toward the magnetosphere. The penetration of the irregularity in the 3‐D model is found to be less efficient than in a two‐dimensional (2‐D) model. Through a comparison of the present results from 3‐D simulations, not much difference has been found in the efficiency for the irregularity to penetrate into the magnetosphere between two situations in which the interstellar field is parallel or antiparallel to the magnetospheric field.
The DoD highperformancecomputing Modernization Program (HPCMP) is firmly grounded in meeting user requirements, as clearly directed by Congress in both the FY94 and FY95 Appropriations Acts. This paper highlights th...
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Future airdrop systems require the development of very large gliding parachutes capable of delivering 21-ton payloads. This airdrop requirement presents new technology barriers which cannot be addressed by previous me...
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作者：
Stanislav V. KlimenkoDirector
Russian Center of Computing for Physics and Technology Institute for High Energy Physics Protvino Moscow Region 142284 Russia klimenko@mx.ihep.su
Stanislav V. Klimenko; Russians Form center of computing for Physics and technology, Computer in Physics, Volume 9, Issue 1, 1 February 1995, Pages 16–17, https
Stanislav V. Klimenko; Russians Form center of computing for Physics and technology, Computer in Physics, Volume 9, Issue 1, 1 February 1995, Pages 16–17, https
Different implementations on a massively parallel computer system of a semi-Lagrangian method within the numerical weather forecast model HIRLAM are presented. In principle semi-Lagrangian methods on massively paralle...
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Different implementations on a massively parallel computer system of a semi-Lagrangian method within the numerical weather forecast model HIRLAM are presented. In principle semi-Lagrangian methods on massively parallel architectures result in irregular communications, i.e., communications between arbitrary processors. It is shown that the fastest implementation increases the total execution time per time step with an acceptable amount in relation to the advantage of applying a semi-Lagrangian method.< >
作者：
FUCHS, CKOPP, GSCHWAB, AJInstitute of Electric Energy Systems and High-Voltage Technology University of Karlsruhe
Kaiserstrasse 12 76128 Karlsruhe Germany Chistophs Fuchs was born in Sinsheim
germany in 1967. He received the Dipl.-Ing degree in electrical engineering at the University of Karlsruhe in 1992. In April 1993 he joined the Institute of Electric Energy Systems and High-Voltage Technolgoy. His current research interests include analytical and numerical calculation of electromagnetic fields in EMC applications and high-performance computing. Gerhard Kopp was born in Karlsruhe
Germany in 1968. He is studying physics at the University of Karlsruhe and is now working towards his diploma. His thesis deals with numeical calculations of electromagnetic fields. Professor Dr.-Ing. A. J. Schwab graduated in electrical engineering at the Universiyt of Karlsruhe. After receiving his Ph.D. degree he worked as a post-doctoral fellow at MIT in 1970/71. He held appointments at the Universities of Darmstadt and dormund and
eventually was appointed EE Full Professor at the University of Karlsruhe. In 1989 he was appointed Director of the ABB Corporate Research Center at Heidelberg Germany. Since 1994 he has worked again as Professor and Director of the Institute for Electric Energy Systems and High-Voltage Technology at the University of Karlsruhe. He is the author of three books on high-voltage measurements electromagnetic compatibility and field theory concepts that have been published in German English Russian an Chinese. He is a member of the German national society of electrical engineers VDE a member of the Conférence Internationale des Grands Réseaux Electriques (CIGRE) Fellow of the IEEE and at present Chairman of the IEEE Germany Section.
This paper presents a new method in TLM for very efficient computation of highly conducting thin shielding walls. Firstly, the impulse response of a finite conducting sheet is computed analytically via inverse Laplace...
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This paper presents a new method in TLM for very efficient computation of highly conducting thin shielding walls. Firstly, the impulse response of a finite conducting sheet is computed analytically via inverse Laplace transform. Subsequently, a recursive convolution integral is formulated with the analytical impulse response. This allows a very efficient and accurate calculation of the diffusion process through imperfectly conducting walls.
To construct numerical schemes of he Godunov type for solving magnetohydrodynamical (MHD) problems, an approximate method of solving the MHD Riemann problem is required in order to calculate the time-averaged fluxes a...
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To construct numerical schemes of he Godunov type for solving magnetohydrodynamical (MHD) problems, an approximate method of solving the MHD Riemann problem is required in order to calculate the time-averaged fluxes at the interfaces of numerical zones, Such an MHD Riemann solver is presented here which treats all waves emanating from the initial discontinuity as themselves discontinuous. Thus shock jump conditions are used for rarefactions, which limits the applicability of this work to weak rarefactions, the case most important for computation. The solutions from our approximate MHD Riamnn solver consist of two fast waves (either shock or rarefaction) two rotational discontinuities, two rarefaction waves (either shock or rarefaction), and one contact discontinuity for a general MHD Riemann problem. In order to display rotational discontinuities, a three-component model is necessary. Only under very limited circumstances is there no rotational discontinuity involved and thus the two component approximation may be used in the MHD Riemann problem. The solutions of the MHD Riemann problem in the shock tube problem which generates the compound wave in the earlier work contain two fast rarefaction waves, two slow shocks, one contact discontinuity, and one rotational discontinuity in our formalism. (C) 1994 Academic Press, Inc.
作者：
DAI, WLWOODWARD, PRSchool of Physics and Astronomy
Supercomputer Institute Army High Performance Computing Research Center University of Minnesota 1100 Washington Avenue South Minneapolis Minnesota 55415
An extension of the piecewise parabolic method to treat multi-dimensional ideal magnetohydrodynamical equations is presented in this paper. The multidimensional scheme is constructed from a one-dimensional functioning...
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An extension of the piecewise parabolic method to treat multi-dimensional ideal magnetohydrodynamical equations is presented in this paper. The multidimensional scheme is constructed from a one-dimensional functioning code based on the dimensional splitting method originally suggested by Strang. The functioning code is built upon a nonlinear Riemann solver for ideal MHD equations recently developed by the authors. The correctness of the scheme is tested in the steepening of waves in both one- and two-dimensional situations and in Various MHD shock-tube problems which involve all the discontinuities in ideal MHD. The robust character of the scheme is demonstrated in the shock-tube problems and in the interaction between MHD shocks and a cloud. The results of these problems show that the scheme keeps the principal advantages of a high-order Godunov scheme: robust operation in the presence of very strong waves, thin shock fronts with little attendant noise generation, and thin contact discontinuity, (C) 1994 Academic Press. Inc.
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