


Since 1978 Published in Sarov (Arzamas16), Nizhegorodskaya oblast 
RUSSIAN FEDERAL NUCLEAR CENTER 
ALLRUSSIAN RESEARCH INSTITUTE OF EXPERIMENTAL PHYSICS 

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Issue N^{o} 4, 2019  A METHOD FOR MULTIDIMENSIONAL ELECTRODYNAMIC SIMULATIONS ON UNSTRUCTURED MESHES
I. V. Sobolev VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 320.
The paper describes numerical simulations of electrodynamic equations on unstructured polyhedral meshes by a secondorder Godunovtype method. For ideal magnetohydrodynamics we use three difference schemes based on an approximate Riemann solver. We also discuss exclusion of the numerical magnetic charge by the CT method. The difference scheme for Maxwell’s equations employs an exact Riemann solver. Test simulations are presented and compared with published data. Key words: Maxwell’s equations, equations of ideal magnetohydrodynamics, Godunov method, unstructured meshes.
 INCORPORATING SPECTRAL AND KINETIC EFFECTS IN THE RADIATIVE HEAT TRANSFER APPROXIMATION FOR RADIATIVE TRANSFER SIMULATIONS N. G. Karlykhanov VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 2131.
The paper considers an approach to averaging the radiative transfer equation over spectrum and angular variable. As distinct from the known methods, the algorithm under consideration reduces an averaged problem to an equation for the radiative heat transfer approximation. It is demonstrated that the simulation results obtained using the proposed algorithm  provided that some conditions are satisfied  are close to the simulation results obtained in the kinetic statement. As applied to optically thick media, this algorithm is shown to naturally transform into the radiative heat transfer approximation with a mean Rosseland path. Key words: heat transfer, quasidiffusion, quasispectral property.
 APPLICATION OF A RELAXATION MODEL OF FRACTURED VISCOELASTICITY FOR THE DESCRIPTION OF HIGHEXPLOSIVE SPECIMEN TESTING USING A SPLITHOPKINSON PRESSURE BAR O. M. Velichko VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 3250.
A singlematerial viscoelastic model of a fractured medium is considered, which has been formulated based on publications of US authors, and its modification for viscous relaxation and fracture growth kinetics is presented. An approximate computational algorithm accelerating the process of model fitting for an HMXbased high explosive has been developed. The fitting is based on the criterion of acceptable agreement between calculated data and results of HE specimen testing on a splitHopkinson pressure bar apparatus from a publication of Russian authors. Numerical modeling of HE specimen deformation is performed based on a computational model implemented by the Godunov method. Key words: HE, deformation and fracture, fractured viscoelastic model, Godunov method, numerical modeling.
 SINGLEPHASE FLOW SIMULATIONS USING AN ALGEBRAIC MULTIGRID SOLVER FOR SYSTEMS OF LINEAR ALGEBRAIC EQUATIONS Yu. N. Deryugin, P. A. Mashenkin VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 5165.
Usability of an algebraic multigrid solver for systems of linear algebraic equations in underground hydrodynamic simulations is considered. A methodology for solving the problems of singlephase flow in nonuniform and anisotropic porous media on unstructured meshes composed of convex nonselfintersecting cells is presented. It is shown experimentally that the efficiency of using the algebraic multigrid solver grows with increasing nonuniformity of bed rock and increasing problem mesh size. The algebraic multigrid solver is compared with the Krylovtype PCG solver in error convergence and computing time. Key words: SLAE (system of linear algebraic equations), algebraic multigrid solver, underground hydrodynamics, approximation on unstructured mesh.
 REPEATED USE OF A HIERARCHICAL DATA STRUCTURE IN AN ALGEBRAIC MULTIGRID SOLVER FOR SYSTEMS OF LINEAR ALGEBRAIC EQUATIONS Yu. G. Bartenev, A. P. Karpov VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 6677.
Repeated use of a hierarchical data structure generated in an algebraic multigrid preconditioner and solver for a series of SLAEs with the same matrix profile is considered. This approach, called partial construction of a multigrid algebraic solver fully preconstructed for a previous SLAE, involves updating merely the coefficients of the preconstructed coarse matrices without changing their structure. Examples of using a combination of full and partial construction of an algebraic multigrid solver in different modifications of its implementation are given. This solver construction approach in the PMLP/ParSol and some other libraries is shown to considerably reduce the time of solving SLAEs in simulations of different physical processes. The issue of adaptive combination of full and partial algebraic multigrid solver construction is discussed in brief. Key words: system of linear algebraic equations, sparse matrices, algebraic multigrid preconditioners and solvers, hydrodynamic equations, aerodynamic equations, equations of heat transfer in solids, equations of liquid diffusion in porous media, equations of radiant heat transfer, series of SLAEs with the same matrix profile, iterative solvers ÑG, BiCGStab.
 "CORIDA": A PROGRAM PACKAGE FOR PREDICTING RADIATION FIELDS BASED ON THE VARIATIONS IN THE PROPERTIES OF RADIATION SOURCES AND ENGINEERING SECURITY BARRIERS A. I. Blokhin, P. A. Blokhin, Yu. E. Vaneev, I. V. Sipachev VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 7887.
The paper describes the functionality and structure of a program package called CORIDA being developed for radiation safety analysis of legacy nuclear facilities and radioactive waste disposal sites. Results of such computations are heavily dependent on the emissive properties of radioactive wastes; that is why the program package includes a nuclide kinetics module. Neutron and photon transport is simulated using the TDMCC code. To simplify the preprocessing procedure in the programspecific format, the program package contains a special graphics editor and a data converter for problem geometry, materials and radiation sources. Results of testing the nuclide kinetics module and the program package as a whole are reported. Key words: program package, radioactive wastes, nuclide kinetics, radiative transfer simulations, graphics editor, data converter, yield, dose rate.
 FUNCTIONALITY OF THE "OptIMUS" VISUALIZATION AND INTEGRATION PLATFORM FOR SIMULATIONS OF WEAPONS AND MILITARY AND SPECIALPURPOSE EQUIPMENT O. V. Kovalenko, I. A. Kryuchkov, A. V. Ogorodnikov, D. V. Ezhov, D. S. Sobanin VANT. Ser.: Mat. Mod. Fiz. Proc. 2019. No 4. P. 8895.
The paper provides an overview of the software approaches and technologies employed in the OptIMUS visualization and integration platform. We demonstrate capabilities of the platform for mutual integration of different technologies, including artificial intelligence (AI), in a single program package for multiagent simulations enabling the development of sophisticated intelligent models of different weapons and military equipment designs. Practical examples are provided to show how these approaches and technologies can be used to simulate physical protection systems and develop predictive models of adversary impact on logistics entities of the Armed Forces of the Russian Federation. Key words: OptIMUS visualization and integration platform, multiagent simulation, artificial intelligence, metaheuristic optimization, intelligent agents, domainspecific language, navigation network, weapons, military and specialpurpose equipment.
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