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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 2, 2017 |
USE OF GRADIENT LIMITERS TO SOLVE NAVIER-STOKES EQUATIONS ON ARBITRARY UNSTRUCTURED GRIDS
S. V. Lashkin, A. S. Kozelkov, E. V. Glazunova, N. V. Tarasova, A. V. Yalozo
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 3-17.
The paper analyses the use of gradient limiters on arbitrarily-shaped unstructured grids in the finite volume methods for the Navier-Stokes equation discretization with the SIMPLE algorithm. The effect of limiters on the accuracy of results obtained using the convective gradient schemes of the second order, as well as the accuracy of gradients calculated using the Green-Gauss iterative algorithm is considered. Simulations of compressible and incompressible flows using grids of different topologies are described. An optimal use of limiters for solving problems with the SIMPLE algorithm is recommended.
Key words: gradient limiters, unstructured grids, Navier-Stokes equations, algorithm SIMPLE.
| | IMPLICIT FINITE-VOLUME TVD METHOD FOR THE NUMERICAL SOLUTION OF THE 2D THERMAL RADIATION TRANSPORT EQUATION IN THE P1-APPROXIMATION A. D. Gadzhiev, I. S. Chubareshko, A. A. Shestakov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 18-29.
The numerical simulation of the heat transport problem in the P1-approximation is discussed in a lot of papers. The given paper considers a new scheme for numerically solving the 2D thermal radiation transport equation in the P1-approximation, which is based on the TVD reconstruction. Results of benchmark simulations are presented.
Key words: radiation transport, TVD reconstruction, P1-approximation.
| | SIMULATION OF 2D MHD PROCESSES USING LAGRANGIAN UNSTRUCTURED GRIDS BY THE EXAMPLE OF SIMULATING OPERATION OF EXPLOSIVE OPENING SWITCHES Yu. V. Vlasov, P. V. Duday, A. I. Panov, A. V. Samodolov, S. S. Sokolov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 30-41.
The TIM-2D code was used for the magnetohydrodynamic (MHD) simulation of the process of current switching by an explosive opening switch. The current switching simulation results are presented for the two types of explosive opening switches: breakage of a conductor on a ribbed barrier and breakage using cumulative dielectric jets. The numerical simulation was performed in Lagrangian variables using unstructured computational grids with regard to elastoplastic properties and damage of materials and diffusion of the magnetic field.
Key words: magnetic explosion generator, explosive opening switch, magnetohydrodynamic simulation, ribbed barrier, cumulative jets, electric blasting, Lagrangian code.
| | THE INFLUENCE OF LASER BEAMS POWER IMBALANCE ON SYMMETRY OF ABSORBED ENERGY IN THE CORONA OF DIRECT-DRIVEN TARGETS I. A. Khimich, V. A. Lykov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 42-52.
The absorption of laser energy has been simulated in the geometrical optics approximation with regard to refraction in an isothermal corona and with the exponential law of the radial electron density distribution. Two target illumination configurations are considered: 1) 6 × 8 clusters around the directions passing through the centers of cube faces; 2) 8 × 6 clusters, which axes of symmetry pass through cube corners. According to simulation results, the mean-root-square deviation of the absorbed laser energy in a solid angle under optimal irradiation conditions is Δ ≈ 0,73% and 6 × 8 и Δ ≈ 0,52% for the 6 × 8 and 8 × 6 configurations, respectively. The absorbed energy expansions in spherical harmonics demonstrate that for the chosen target illumination configurations the leading ones are harmonics 4 and 8. The power imbalance of laser beams taken into account in simulations beams leads to degradation of symmetry in the absorbed energy distribution and occurrence of lower harmonics. The mean-root-square deviation of the absorbed laser energy does not exceed 1% , with the standard deviation in the laser beams power not exceeding 3% and 5% for the 6 × 8 and 8 × 6 illumination configurations, respectively.
Key words: direct-driven targets, a megajoule laser facility, power imbalance of laser beams, non-uniformity of absorbed energy.
| | AN ALGORITHM OF CORRECTING A GRID WITH RESPECT TO A DEFORMED DOMAIN OF REVOLUTION O. V. Ushakova
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 53-65.
An algorithm is proposed for correcting boundary nodes of a structured grid with respect to the boundary of a domain of revolution deformed by the pressure of another domain of revolution. A domain of revolution is formed, if a plane generator of a curve consisting of line segments, arcs of circles, and ellipses is turned through 180° around axis. A grid correction algorithm is the necessary step in constructing grids in domains of interest and during the grid reconstruction it allows moving boundary grid nodes directly along the domain boundary – surfaces of revolution of the deformed and deforming bodies, rather than moving them over ruled surfaces of cell faces of the original grid constructed for the domain discretization. The proposed algorithm may be also used independently to reconstruct a grid, whose nodes left the domain boundary. The algorithm implemented in software systems for generating 3D grids and in individual codes in C++ for correcting a grid with respect to a domain boundary allows significantly increasing the effectiveness of mathematical modeling of multicomponent media.
Key words: grids, boundary nodes, domains of revolution, projection.
| | PROSPECTS FOR CREATING MAIN SECURED FIBER-OPTIC SYSTEMS FOR CLASSIFIED DATA TRANSMISSION O. N. Naryshkina, A. V. Svetikov, V. V.Shubin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 66-78.
The paper considers prospects for creating main secured fiber-optic systems to transmit classified data. The standard schematic diagram of such a system and its main parameters are presented. The principal requirements to optical amplifiers used in secured fiber-optic systems are given. The specific features of using equipment to secure the system against data leakage from an optical data link are shown. Experimental investigation results are presented for a pilot 21-link 7-path secured system.
Key words: main secured fiber-optic transmission system, security controller, optical EDFA pre-amplifier.
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