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RUSSIAN FEDERAL NUCLEAR CENTER 
ALLRUSSIAN RESEARCH INSTITUTE OF EXPERIMENTAL PHYSICS 

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Issue N^{o} 2, 2017  USE OF GRADIENT LIMITERS TO SOLVE NAVIERSTOKES 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. 317.
The paper analyses the use of gradient limiters on arbitrarilyshaped unstructured grids in the finite volume methods for the NavierStokes 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 GreenGauss 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, NavierStokes equations, algorithm SIMPLE.
 IMPLICIT FINITEVOLUME TVD METHOD FOR THE NUMERICAL SOLUTION OF THE 2D THERMAL RADIATION TRANSPORT EQUATION IN THE P_{1}APPROXIMATION A. D. Gadzhiev, I. S. Chubareshko, A. A. Shestakov VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 1829.
The numerical simulation of the heat transport problem in the P_{1}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 P_{1}approximation, which is based on the TVD reconstruction. Results of benchmark simulations are presented. Key words: radiation transport, TVD reconstruction, P_{1}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. 3041.
The TIM2D 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 DIRECTDRIVEN TARGETS I. A. Khimich, V. A. Lykov VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 4252.
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 meanrootsquare 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 meanrootsquare 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: directdriven targets, a megajoule laser facility, power imbalance of laser beams, nonuniformity 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. 5365.
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 FIBEROPTIC SYSTEMS FOR CLASSIFIED DATA TRANSMISSION O. N. Naryshkina, A. V. Svetikov, V. V.Shubin VANT. Ser.: Mat. Mod. Fiz. Proc. 2017. No 2. P. 6678.
The paper considers prospects for creating main secured fiberoptic 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 fiberoptic 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 21link 7path secured system. Key words: main secured fiberoptic transmission system, security controller, optical EDFA preamplifier.
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