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RUSSIAN FEDERAL NUCLEAR CENTER 
ALLRUSSIAN RESEARCH INSTITUTE OF EXPERIMENTAL PHYSICS 

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Issue N^{o} 2, 2014  TECHNIQUE FOR NEUTRON SCATTERING ANISOTROPY MODELING IN P_{n}APPROXIMATION
A. N. Ivanov, N. V. Ivanov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 313.
In the multigroup approximation the neutron scattering anisotropy is described by the coefficients of expansion into Legendre polynomials. At numerical problem solving the low order expansions of three or five terms are usually employed. The scattering angle cosine distribution density, retrieved from such expansions, can have negative values, which makes impossible solving the transport problems with the MonteCarlo method in the same setting with difference methods. To avoid this, the initial density is replaced by the equivalent discrete density. The equivalency is understood as the agreement of the density moments. To smoothen the radial effect, the combination of triangular densities preserving the first two initial density moments is added to the discrete density. Key words: MonteCarlo method, neutron transport, scattering anisotropy, multigroup approximation.
 COMPARATIVE ANALYSIS OF THE QUASIDIFFUSION APPROACH AND THE AVERAGED COSINE METHOD FOR SOLVING RADIATION TRANSPORT KINETIC EQUATION IN A SCATTERING AND ABSORBING MEDIUM A. S. Isakova, N. G. Karlykhanov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 1426.
The paper studies the properties of kinetic equation solutions in scattering and absorbing medium on the example of problem calculations with known numerical and (or) analytical solutions using the quasidiffusion method and the method of averaged cosines. The paper shows that the method of averaged cosines along with the TVDapproachbased difference scheme gives more accurate solutions, especially in layered systems, as compared with the quasidiffusion method, for which the traditional difference scheme with the second order of accuracy has been built. Key words: radiation transport, scattering and absorbing medium, quasidiffusion, onemoment transport equations with averaged cosines.
 ON LIQUID CONTRACTION OF A GRID CELL IN THE VOF METHOD S. V. Yatsevich VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 2735.
This paper considers the problem of liquid contraction of a polyhedral grid cell with nonplanar faces at the geometrical reconstruction in the VOF method for numerical solving problems with free surfaces. The paper gives the description of the constructive approach: the form of the working function is determined, its construction is presented. The authors offer the corresponding algorithm of the liquid contraction determination at the free surface piecewiseplanar reconstruction. Key words: free surface, geometrical reconstruction, liquid contraction, grid cell, working function.
 TECHNIQUE OF FATIGUE STRENGTH ESTIMATION FOR MECHANICAL STRUCTURE PARTS UNDER MULTISTAGE RANDOM VIBRATIONAL LOAD N. A. Bilyk, T. N. Artem'eva VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 3644.
The paper describes the method and the algorithm of fatigue strength estimation for mechanical structure parts under multistage random vibration with random spectrum. The acting load is determined at the piece mounting points or on the unsafe crosssection of the part. The method allows the estimation of the part fatigue breakdown probability, the level of cumulative damage at each load stage and for the whole loading period, the mean value and the rootmeansquare deviation of the part lifetime logarithm. The program complex realizing this approach has been created for an AWP. The fatigue strength and the strength reliability were calculated for copper and steel piping under the impact of threestage random vibration at the piece mounting points. The proposed approach is able to decrease the cost of designing and mechanical structures development, and to reduce the duration of preproduction efforts. Key words: random vibration, multistage random vibration, part lifetime, level of cumulative damage, reliability index.
 HYBRID MICROTARGET MODELING FOR INERTIAL HEAVY ION FUSION WITH ACCOUNT FOR NEUTRONNUCLEAR REACTIONS V. T. Zhukov, E. A. Zabrodina, V. S. Imshennik, M. V. Maslennikov, O. V. Nikolayeva, M. D. Churazov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 4558.
A theoretical and calculational justification of the U shell (pusher) using to significantly increase the energy yield was previously made for the hybrid inertial heavy ion fusion power microtarget. This justification included the accounting for the neutronnuclear reactions in the pusher, formulated as generalized Akhiezer and Pomeranchuk solutions for cylindrical symmetry. This paper shows the results of such microtarget study basing on a later more comprehensive mathematical model describing the neutronnuclear processes in the multigroup approximation. The process of microtarget implosion is described in the 3temperature hydrodynamic approximation with account for the thermonuclear reaction kinetics, typical for the deuteriumtritium fuel. The paper includes the results of optimized calculations, proving the prospective character of the hybrid inertial heavy ion fusion microtargets when the natural uranium is used as the pusher material. Key words: hybrid microtarget, neutron transport equation.
 TECHNIQUE FOR GASDYNAMIC QUANTITY TRANSFER FROM ONE REGULAR 3D GRID TO ANOTHER WITH ACCOUNT FOR REESTABLISHED MATERIALS INTERFACE IN MIXED CELLS N. V. Chukhmanov, I. V. Syrov, D. V. Zubanov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 5968.
The paper considers the possibility of gasdynamic quantity transfer from one 3D regularly structured grid to another with account for reestablished materials' interface in mixed cells in the frames of the InterVal3D program. The paper describes the InterVal3D program, its abilities, as well as the underlying recalculation principles. The realized materials' interface reestablishing algorithm is described. The comparative analysis of the recalculation results obtained using the interface reestablishing algorithm and without it in model problems with different spatial grids is given. Key words: InterVal3D program, reinterpolation of gasdynamic quantities, IFP (Integrated File Profile) library, interface, adapted Youngs method.
 PARALLELIZATION METHOD USING 2D GRID DECOMPOSITION FOR NUMERICAL SOLVING THE PROBLEM OF THE 2D THERMAL CONDUCTIVITY EQUATION USING THE KORONA2D TECHNIQUE V. V. Lyapin, R. A. Korolev, A. V. Vetchinnikov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 6977.
The paper describes the parallelization method using 2D grid decomposition, when the lines along each column, calculated on a processor, are overlaid into one and the same column and the whole range. This approach ensures the information completeness on both geometric and thermodynamic parameters of the cells independently of the grid nonorthagonality degree. The paper shows the results of the parallelization accuracy and efficiency test calculations, obtained at different variants of grid decomposition. Key words: KORONA technique, 2D equation of thermal conductivity, 2D grid decomposition, NEWT parallel solver.
 LOGOSPREPOST PREPOSTPROCESSOR. BUSINESSLOGICS LEVEL ARCHITECTURE, DATA STORAGE, IMPORT AND EXPORT A. A. Anishchenko, V. I. Deryugin, V. N. Dyupin, K. V. Ivanov, A. S. Santalov, E. E. Santalova VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 2. P. 7882.
The paper describes the businesslogics level architecture of the LOGOSPrepost program application which is a component of the LOGOS simulation program complex. The paper describes the businesslogics level interaction with the representation and data levels; the issues of data storage, import and export are tackled upon. The solutions which make the application flexible, adjustable and easily upgradable are indicated. Key words: prepostprocessor, LOGOS, architecture, businesslogics, data import, data export.
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