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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 4, 2010 |
ACCOUNTING FOR TRANSPORT EFFECTS IN RADIATION TRANSPORT SIMULATIONS IN THE DIFFUSION APPROXIMATION
N. G. Karlykhanov, M. Yu. Kozmanov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 3-9.
Two approaches for including transport effects in radiation transport simulations in the spectral diffusion approximation are considered. The range of applicability of the proposed approaches is studied. It is shown that the simulation results obtained using the proposed approaches - provided that some conditions are satisfied - are close to the simulation results obtained in the transport statement.
Key words: radiation transport, spectral quasi-diffusion, spectral diffusion, accounting for transport effects.
| | MATHEMATICAL MODELING OF SHOCK-WAVE VISCOUS HEAT-CONDUCTING GAS FLOWS BASED ON THE ASYMPTOTIC MODEL A. L. Adrianov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 10-26.
We model the interaction of a pressure discontinuity with a shear layer in viscous and non-viscous problem statements. The pressure discontinuity is represented schematically by a curvilinear surface of a strong gas dynamic discontinuity, which satisfies generalized zero- and first-order asymptotic relations accounting for viscosity and heat conduction. A time-independent analytical solution to the problem is obtained. One of particular solutions is compared with the corresponding numerical solution of complete Navier-Stokes equations. It is shown that explicit neglecting of this viscosity-heat conduction factor in the differential model in perturbed flow simulations may lead to a wrong result. The influence of the boundary effect on the viscosity-heat conduction factor is analyzed.
Key words: curvilinear pressure discontinuity, viscous heat-conducting perfect gas, shear layer, schematic representation of pressure discontinuity as a surface of strong gas dynamic discontinuity, generalized differential conditions (relationships) on curvilinear pressure discontinuity, Navier-Stokes equations, Reynolds number, asymptotic approach, boundary effect, additional differential constraint, vortexlb model, non-viscous solution, analytical solution.
| | ON TEMPERATURE DEPENDENCE OF INTERATOMIC POTENTIAL FOR MOLECULAR DYNAMICS SIMULATION OF URANIUM DIOXIDE PROPERTIES Yu. S. Nagornov, R. Yu. Makhmud-Akhunov, B. М. Kostishko, V. N. Golovanov, V. V. Svetukhin, А. V. Kats
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 27-34.
The new approach to choose the interatomic interaction potential for simulation of thermal properties change of stoichiometric uranium dioxide using molecular dynamics method has been applied. According to Ehrenfest theorem and time averaged interaction potential, the potential parameters have been chosen as slowly varying temperature dependencies. The calculated values of constant grid, enthalpy and heat capacities for constant volume and pressure agree with test data within small limits for a wide range of temperatures from 250 tolb 3,150 K, which is confirmed by perspectiveness of the given approach.
Key words: molecular dynamics, uranium dioxide, simulation, potential.
| | AN INTEGRATED SIMULATION SUPPORT SYSTEM FOR THE LEGAK-3D CODE P. A. Avdeev, M. V. Artamonov, S. M. Bakhrakh, S. V. Velichko, V. F. Spiridonov, M. M. Pristash
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 35-43.
We discuss a service part of the LEGAK-3D code, which serves for pre-processing, simulation support and post-processing of simulation results. In addition to different kinds of visualization and editing of all problem components, the system enables high-level operations with these components (design), such as transfer of components from one section to another with addition of new or replacement of existing components. Analysis of simulation results is provided both by means of context menu during data display, and by individual tools (including external applications).
Key words: LEGAK-3D code, simulation support, post-processing, problem section.
| | INTEGRAL PERFORMANCE INDICES FOR MULTIPROCESSORS Yu. G. Bartenev, G. G. Bliznyuk, Yu. V. Logvin, Yu. V. Shatokhina
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 44-51.
Described here is the calculation technique of the main integral performance indices for multiprocessors in terms of hardware operation (operability, loss due to fault/fail, maintenance and downtime of equipment), as well as in terms of hardware efficiency (parallel problems load, mean size of counting problems, CPU downtime).
Evaluation technique has been developed for CPU downtime due to fault/fail of different components of computation system and reliability figure analysis characterizing performance reliability of robust component subset of computational system.
The common form for integral performance indices of computation systems has been suggested for the enterprises using different multiprocessor systems, which gives the possibility to compare the operation efficiency.
Given here is the integral performance indices calculation for real computation systems using the described technique.
Key words: multiprocessor performance, multiprocessor efficiency, multiprocessor computation indices.
| | SOME DATA FORMATS FOR REPRESENTATION OF ARBITRARY-TYPE 2D UNSTRUCTURED GRIDS A. A. Voropinov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 52-63.
A number of data formats are considered for the representation of arbitrary-type 2D (surface) unstructured grids (composed of arbitrary polygons, with an arbitrary number of edges in nodes). The proposed data formats use the principle of distinguishing the grid's key element. We provide measured memory consumption and estimated speed of processing for the proposed data formats. The overhead for executing the algorithms to collect grid element neighborhood data was measured for the case of gas dynamics simulations using the TIM-2D code.
Key words: arbitrary-type unstructured grid, data format.
| | A NEUTRON SOURCE FOR A HYBRID (FUSION + FISSION) SYSTEM E. A. Zabrodina, D. G. Koshkarev, M. D. Churazov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 64-70.
Steady-state burning of a deuterium streem in the Z-pinch configuration is considered in the hydrodynamic approximation. Assessment of the possible use of produced neutrons in a hybrid (Fusion + Fission) energy system is provided.
Key words: hybrid energy system, Z-pinch, deuterium plasma streem, uranium blanket.
| | ON REGULAR RECOVERY ALGORITHM FOR NON-SMOOTH SOLUTIONS OF FREDHOLM INTEGRAL EQUATIONS OF THE FIRST KIND Т. I. Serezhnikova
VANT. Ser.: Mat. Mod. Fiz. Proc. 2010. No 4. P. 71-78.
Analyzed here is the technique and numerical experiments for (one-dimensional) Fredholm integral equations of the first kind at geophysical field extension and antenna synthesis.
The regular algorithm is based on Tykhonov regularity using Lipschitz space norm function as a stabilizer, additional use of prox-technique and subgradient processes for non-smooth minimization problems. The short description of the used convergence theorems (with references) and subgradients applicability is given.
Simulation results are described; estimated accuracy is given as well as recommendations for practical parameterization of computations and accuracy control.
Numerical experiments confirm that the suggested technique can be used in mathematical simulation of various applied problems to reestablish Fredholm integral equation of the first kind. The given technique can be used to reestablish smooth (continuous) solutions, as well as kinked, discontinuous, maximum-close solutions.
Key words: Fredholm integral equation, non-smooth solution, Tykhonov regularity, proximal method, subgradient process.
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