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RUSSIAN FEDERAL NUCLEAR CENTER 
ALLRUSSIAN RESEARCH INSTITUTE OF EXPERIMENTAL PHYSICS 

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Issue N^{o} 3, 2005  TURBULENT MIXING OF TWO FLUIDS OF DIFFERENT DENSITY AND SPEED MOVING IN A GRAVITATIONAL FIELD
T. V. Zabolotnikova, V. E. Neuvazhaev VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 313.
Two fluids of different density located in a gravitational field move with different speed relatively to one another. A case is studied when Reynolds number is large enough, therefore the interface is unstable to small perturbations, it collapses and turbulent mixing takes place. Turbulent mixing appearing as a result of joint action of shear and gravitational instability is theoretically studied. Based on fcemodel an analytical formula for the width of a turbulent mixing zone was derived depending on the initial parameters of the problem: Atwood number , number , acceleration g and initial roughness L_{0} where U_{1} and U_{2}, ρ_{1} and ρ_{2} are speeds and densities of fluids, respectively (a similar formula was derived for lvmodel earlier).
 CUMULATIVE CHARACTER OF INSTABILITY OF A CONDENSED MATTER CURVED SURFACE UNDER SHOCKWAVE LOADING S. M. Bakhrakh, I. Yu. Bezrukova, A. D. Kovaleva, S. S. Kosarim, O. V. Ol’khov VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 1425.
The results of a designtheoretical analysis of the processes taking place on plane shock wave coming to a curved free surface of a condensed matter are set out. It is shown that incipient instability can be of stream formation character. Basic regularities describing development and growth of cumulative disturbances depending on starting conditions and some flow properties of materials are presented.
 NUMERICAL SIMULATIONS OF ID RADIATION TRANSPORT TEST PROBLEMS V. V. Zav’yalov, M. Yu. Kozmanov, V. N. Seleznev, V. E. Chernyakov, A. A. Shestakov VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 2636.
Testing is one of the necessary aspects in development of numerical techniques. When testing a technique it is desirable to use problems having analytical solutions. If there are no such problems the usual practice is to use problems computed to convergence with high mesh refinement. These data are used instead of exact solutions. Numerical simulation results of three ID radiation transport test problems are considered in the paper. The first problem is a widely used test of radiation transport. However, it does not have an exact solution; therefore, numerical simulations with very fine meshes are used to analyze difference techniques. Other problems are based on analytical solutions, which significantly simplify testing of techniques.
 TECHNIQUE TIM FOR CALCULATION OF THREEDIMENSIONAL PROBLEMS OF MECHANICS OF CONTINUA ON UNSTRUCTURED POLYHEDRAL LAGRANGIAN GRIDS S. S. Sokolov, A. L Panov, A. A, Voropinov, I. G. Novikov, I. V. Sobolev, A. V, Yalozo VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 3752.
Technique TIM destined for calculation of threedimensional problems of mechanics of continua on unstructured polyhedral Lagrangian grids is considered. The technique allows to carry out calculations on grids with arbitrary number of relations in nodes (the number of adjoining meshes, edges and faces). The technique is operable on unstructured polyhedral grids of Dirichlet—Voronoy type (four edges converge in each node), on hexahedral grids (six edges converge in each node) and on unstructured polyhedral grids with arbitrary number of relations in nodes. Single calculating algorithms are used for all types of grids. Calculation of initial data and solution of mechanics of continua problems are carried out on the right Cartesian display. To numerically solve the problems of gasdynamics, nonstationary elastoplastic ity and magnetohydrodynamics explicit finitedifference schemes are used; kinematic quantities are kept in countable grid nodes and thermodynamic quantities — in mesh centers. To calculate heat conductivity problems implicit finitedifference scheme is applied.
 SIMULATION OF MELT KEEPING IN A FAST REACTOR VESSEL UNDER SEVERE ACCIDENT CONDITIONS M. V. Kashcheev, I. A. Kuznetsov VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 5364.
The simulator of processes of melt keeping in a fast reactor vessel under fuel assemblies destruction was developed. Mass, momentum and energy conservation equations were solved in a region composed of 15 subregions. Formation of a heatgenerating layer was considered. Correlations for determination of layer formation time and its thickness were found. Simulation of layer zones was conducted. Calculation of boiling and condensation processes for sodium and steel was carried out. Heat sinks in a heat exchangers zone were obtained. The developed simulator is implemented as BRUT program. Using it calculation of molten fuel keeping in a fast reactor vessel under destruction of 6 and 36 fuel assemblies as well as under full melting of an active zone occurring as a result of secondary criticality appearance on prompt neutrons was conducted. On the basis of the conducted simulation we can assert that keeping of a destroyed active zone in a reactor vessel is ensured without its melting.
 APPLICATION OF THE KALMAN FILTERING TECHNIQUE FOR ESTIMATION OF DYNAMIC CHARACTERISTICS OF A FLUING VEHICLE V. M. Ponyatskii VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 6571.
The problem of estimation of parameters of a flying vehicle dynamic model by telemetry data is considered. Estimation is carried out using the Kalman filtering technique. The quality of model identification is conducted with the help of Fisher’s criterion and ecriterion. The results of evaluation of glider and steering gear time constant are presented.
 TRANSPORT PROCEDURES IN POROUS MATTERS: CAPILLARY EFFECTS (MODERN FOREIGN LITERATURE REVIEW) K. A. Potashev, N. D. Yakimov, L P. Breus VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 7279.
The review of the foreign literature dealing with simulation of multiphase flows in porous matters and the related capillary effects appearing on phase interfaces was conducted. The central moment of investigations is revelation of dependence of capillary pressure and relative phase permeability upon saturation, surface tension and other characteristics of porous matters and saturating phases. Statement of facts is mainly based on works dealt with different ecological problems: the forecast of region and rate of soil pollution by liquid matters and investigation of various ways of their penetration into natural porous matters; optimization and designing of artificial capillary barriers capable of containing or taking aside polluting flows from sensitive regions of natural matters; development of methods of polluted soils recovery.
 SIMULATION OF ION MOBILITY IN SOILS AND CLAYEY GROUNDS T. Z. Lygina, M. G. Khramchenkov, R. Kh. Khramchenkova VANT. Ser.: Mat. Mod. Fiz. Proc. 2005. No 3. P. 8085.
The results of mathematical simulation of ion mobility in soils and clayey grounds are presented. Calculations were carried out on the basis of the osmotic cell conception developed by one of the authors. Comparison of the calculations with the experimental data was made. Close fit was obtained that confirmed experimental validity of the used model.
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