2014

NUMERICAL SIMULATIONS OF REGULAR LOCAL PERTURBATION AND TURBULENT MIXING DEVELOPMENT BEHIND VARIOUS-INTENSITY SHOCK WAVES / V. P. Statsenko, Yu. V. Yanilkin, O. G. Sin’kova, O. O. Toporova // P. 3–17.
Development of turbulent mixing and regular local perturbation at an air/SF6 interface driven by a shock traveling through a shock tube with Mach 1.7 to 9.1 in SF6  is explored using the EGAK and TREK codes. We consider the cases of v-shaped and hemicylindrical local perturbation. The calculations were done using 2D and 3D direct numerical simulations. Simulation results were compared with known experimental data.
Keywords: direct numerical simulations, turbulent mixing, local perturbation, turbulent mixing zone, interface, Mach number.

A KINETIC MODEL OF DAMAGE RECOMPACTION IN MATERIALS WITH STRENGTH  / O. N. Ignatova, V. A. Raevsky, I. S. Tselikov //  P. 18 –23.
Recompaction of defects produced by pulsed tensile stresses is not clearly understood today. Simulations are often done using simplified mathematical models that fail to reproduce all recompaction effects.
We propose a damage recompaction model based on the description of the recovery of a single void accounting for the elastoplastic properties of matter. To describe the convergence of voids distributed in the bulk, we consider motion of one special cell in ideally plastic incompressible matter. Using this approximation, we obtained an analytical solution representing the dependence of integral damage on pressure, shear strength and initial damage.
Equations are derived to describe the kinetics of damage recompaction for the case of an arbitrary pressure-time relationship and varied yield strength.
Keywords: damage, recompaction, model, pressure, yield strength, matter with strength.

THE EGAK-MP6 SIX-FLUX 2D-CODE FOR SIMULATIONS OF RAREFIED PLASMA FORMATION AND MOTION IN MAGNETIC FIELD / I. M. Anisina, M. Yu. Eguzhova, V. A. Zhmailo, O. E. Kochetkova, Yu. V. Yanilkin  // P. 24–37.
The paper describes a multi-flux model for simulations of rarefied plasma formation and motion in the geomagnetic field (the multi-flux magneto-hydrodynamic approximation). The 2D-code EGAK-MP6 presented in the paper employs a six-flux modification of this model. Results of Starfish nuclear explosion simulations using the code are reported. The simulation results are compared with existing experimental data.
Keywords: nuclear explosion, Starfish test, EGAK-MP6 code, magnetic field.

AN ANALYTICAL SOLUTION TO THE BENCHMARK PROBLEM OF LASER INTERACTION WITH A FLAT LAYER OF ELECTRON PLASMA / A. I. Golubev, N. P. Pyatakov //P. 38–48.
A benchmark problem of laser interaction with a flat layer of spatially uniform electron plasma is specified. A number of assumptions are made to move from Vlasov’s kinetic equation for electron plasma to a simple hydrodynamic model.
An analytical solution to the problem is obtained. It can be used to test programs for numerical analysis of laser/plasma interaction and for preliminary estimation of spatial steps in such analysis.
Keywords: collisionless plasma, Maxwell’s equations, Vlasov’s equation, hydrodynamic model.

CALCULATIONS OF THE ISOTOPIC COMPOSITION OF REACTOR FUEL IN BURNUP AND RESIDUAL ENERGY RELEASE SIMULATIONS USING THE CONCORD SOFTWARE PACKAGE /  S. V. Mzhachikh, A. V. Alexeev, A. N. Grebennikov, E. A. Gusev, A. A. Ermakov, E. A. Irinichev, S. S. Kasatkin, N. A. Krut’ko // P. 49–64.
Evolution of physical characteristics of an operating reactor is basically governed by the variation of the nuclide composition of its fuel. In addition, it is extremely important to know the isotopic composition, because it underlies safety studies of handling spent nuclear fuel during its storage, transportation and reprocessing.
We describe a software module of the CONCORD package that serves to simulate the process of nuclear kinetics in slow and fast reactors. Sources of data of the module are listed, and methods and models employed are described.
 Keywords: nuclear reactor, isotope kinetics, mathematical modeling, fission fragments, actinide burnup, stiff differential system, Rosenbrock-Wanner difference scheme.

ACCOUNTING FOR UNRESOLVED RESONANCES IN MONTE-CARLO SIMULATIONS OF THE NEUTRON TRANSPORT EQUATION / E. V. Artemieva, N. V. Ivanov, A. G. Mal’kin, T. V. Semenova // P. 65–74.
For a number of isotopes there exists an energy range with unresolved resonances. A special feature of this range is that cross sections at each energy point in this range are random functions, the values of which are determined by statistic laws of distribution of resonance parameters. Two methods of accounting for the unresolved resonances are considered: the method of probability tables and the direct method. The necessity of accounting for the unresolved resonances in neutron transport problems is illustrated by numerical simulations.
Keywords: Monte-Carlo method, neutron transport, unresolved resonances.

THE VERTICAL STRATIFICATION MODEL IN THE SOKRAT-BN THERMAL HYDRAULIC CODE / I. S. Vozhakov, E. V. Usov, D. G. Arkhipov, A. A. Butov, M. E. Kuznetsova // P. 75–81 .
We propose a model that enables physically consistent description of the dynamics of a two-phase vertical stratified flow using a two-fluid approximation with equal phase pressures. This model is based on a modification of the finite-difference approximation of convective terms in the mass and pressure gradient conservation equations accounting for the presence of a distinct boundary between the phases. Examples of consistent stratified two-phase flow simulations are presented.
Keywords: vertical stratification, two-fluid model, SOKRAT-BN.
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