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Since 1978
Published in Sarov (Arzamas-16), Nizhegorodskaya oblast |
RUSSIAN FEDERAL
NUCLEAR CENTER -
ALL-RUSSIAN RESEARCH INSTITUTE
OF EXPERIMENTAL PHYSICS |
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 Русский |  English
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Issue No 3, 2013 |
THE METHOD OF DISCRETE ORDINATES WITH TVD-RECON STRUCTION AND A SYNTHETIC METHOD OF ITERATION ACCELERATION FOR THE NUMERICAL SOLUTION OF HEAT TRANSPORT EQUATION
A. A. Gadzhiev, D. A. Koshutin, A. A. Shestakov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 3-15.
The development of an effective numerical scheme to solve the heat transport equation is a complex problem. The paper describes a new technique for the numerical solution of 1D heat transport equation. The idea of this new approach consists in applying the method of discrete ordinates with TVD-reconstruction to solve the transport equation and a synthetic method on the base of P1-application to accelerate convergence of iterations when solving the transport equation together with the energy equation.
Key words: radiation transport, TVD-scheme, iterative method.
| | COMPARATIVE ANALYSIS OF QUASI-DIFFUSION APPROACH AND METHOD OF AVERAGED COSINES FOR SOLVING THE RADIATION TRANSPORT EQUATION A. S. Isakova, N. G. Karlykhanov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 16-29.
Properties of the transport equation solutions obtained with the quasi-diffusion method and method of averaged cosines were studied by the example of problems having analytical solutions. It is shown that the method of averaged cosines can give a less accurate result in comparison with the quasi-diffusion method. Basing on the comparative analysis the paper offers to use a combination of the two methods, i.e. at each point of space preference is automatically given to the method providing the highest accuracy of solution.
Key words: radiation transport, quasi-diffusion, TVD-approach, single transport equations with averaged cosines.
| | ABOUT ONE FEATURE OF TWO SIMMETRICALLY CONVERGING PLANE WAVES OF FUSION BURN K. V. Khishchenko, A. A. Charakhchian
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 30-40.
The paper considers a 1D problem of two equal laser pulses simultaneously and symmetrically impacting a plane solid DT-fuel layer. There have been studied two options with different initial densities of mixture: normal density  at atmospheric pressure and density . The problem is set up for equations of single-speed two-temperature hydrodynamics with regard to electron and ion heat conduction, intrinsic plasma emission, and fuel heating by  -particles from the primary DT-reaction and laser radiation, which is absorbed completely in the vicinity of point with critical density. The study is focused on fusion burn waves converging to the plane of symmetry and emerging at some choice of the layer thickness and laser radiation parameters. It is shown that such waves have an interesting feature: a flow with compression velocity profile  , where tangent of slope angle  increases with time t with respect to space coordinate x, occurs in front of the combustion wave. As a result, quick compression (relative to a cold fuel) takes place in front of the wave. With the initial density of fuel , the density of fuel in front of the wave becomes 100 times (and even more) higher and comparable with the density expected from the use of the first driver according to the concept of quick ignition. The neutron energy gain of DT-reaction is ~ 45 for initial density and ~ 500 for initial density .
Key words: inertial confinement fusion, slow combustion wave, fusion burn wave, flows with linear velocity profile.
| | MATHEMATICAL AND NUMERICAL MODELS OF THE OVERLAND RUNOFF OF RAINFALLS ON THE RIVER SYSTEM’S DRAINAGE SURFACE V. M. Konyukhov, A. A. Saveliev, M. G. Khramchenkov, A. N. Chekalin, N. E. Galiullina
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 41-54.
The mathematical modeling and numerical simulation issues are considered for the overland runoff of rainfalls on the river system’s drainage surface. A mathematical model includes equations of a 2D kinematic wave, space-and-time variations of the water layer thickness on the drainage surface with regard to rainfalls and water absorption. The paper offers an approximate approach based on the capillary imbibition model to determine the water content in subsaturation area (soil). The specific features of solutions to the problem have been studied. It is shown, in particular, that no overland runoff is generated at initial time of liquid falls because water is completely absorbed by soil. The retarded argument and the overland runoff origination time are calculated from the algebraic equation system. If rainfalls continue after a short period of no falls the retarded argument value should be recalculated. The finite-difference method is used to solve the problem numerically. An algorithmic model has been developed and implemented in the software system that allows the surface water runoff calculations. The paper gives an example of studies for the overland runoff in the Mesha river basin in the Republic of Tatarstan.
Key words: numerical simulation, kinematic wave, overland runoff, drainage surface, subsaturation area, capillary imbibition.
| | S-MPI SOFTWARE SYSTEM FOR THE DEVELOPMENT, OPTIMIZATION AND EXECUTION OF PARALLEL APPLICATIONS ON SUPERCOMPUTER CLUSTERS G. I. Voronov, V. D. Trushchin, V. V. Shumilin, D. V. Yezhov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 55-60.
Effective, reliable and easy-to-use software systems that support MPI-2 standard and provide quick development, optimization and execution of massively parallel applications are needed to effectively use advanced computing clusters. Implementation of such software systems requires resolving a set of theoretic and practical problems and of most importance among them are the problems of scalability, resilience, adaptation to advanced communication environments, etc. The paper describes S-MPI software system developed under contract with the RF Ministry of Education and Science, which includes S-MPI library and tools for the analysis of validity and efficiency of parallel applications. The S-MPI performance is compared with those of the two other commonly used MPI-2 implementations.
Key words: MPI, parallel computations, validation, tools for analysis.
| | IMPLEMENTATION OF PROCESS BINDING TOOLS IN MPI LIBRARY TO IMPROVE THE PERFORMANCE OF PARALLE APPLICATIONS A. V. Baiduraev, S. I. Sapronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 61-64.
The paper describes original tools providing reservation of certain computational resources for a given process during the application runtime. These tools integrated within the particular MPI implementation allow parallel applications to use the given computation environment more effectively and thereby improve the performances of applications and enhance the given implementation competitiveness. In addition to their target function, the binding tools collect a large set of data on the application execution environment to provide a wide spectrum of information services. The user interface of tools has been implemented with the mechanism of environment variables and options in a command line used to start up an application. The user command semantics is oriented to an abstract model of the multicore cluster architecture. The source code structure allows easily integrating binding tools within the particular MPI implementation.
Key words: MPI, parallel computations, allocation, reservation.
| | PARALLEL APPLICATION DEBUGGER (PDB) V. K. Fedorov, S. N. Kiselev
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 65-71.
Capabilities of an interactive debugger of parallel applications are described. The interaction pattern is given for the program components of the debugger and the user interface with its main components is described. The paper also presents the user interface. The debugger is oriented to Unix/Linux platforms. It provides debugging programs written in C, C++, and Fortran with the use of MPI and OpenMP standards.
Key words: multiprocessor computing system, debugger, parallel application.
| | EFRVIEWER PROGRAM FOR NUMERICAL ANALYSIS OF ORIGINAL AND CALCULATED DATA IN NUMERICAL SIMULATION OF PHYSICAL PROCESSES N. V. Popova, A. K. Menshikova
VANT. Ser.: Mat. Mod. Fiz. Proc. 2013. No 3. P. 72-78.
The paper describes EFRVIEWER application. It is intended for viewing, editing and processing data resulted from the numerical simulation of physical processes using the RFNC-VNIIEF application suits and represented in the form of binaries in EFR format. Being a kind of service utility EFRVIEWER provides (via GUI) the user access to the job’s binary code in an easy-to-use form by means of hypertext, tables and plots.
Key words: EFR library, EFR format, user interface, job, cutest, time step, domain, array, grid, numerical analysis, viewing, editing, search, comparison, heterogeneous computer complex.
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