TURBULENT MIXING IN CYLINDRICAL EXPERIMENTS OF MESHKOV-NEVMERZHITSKY (THEORY AND COMPUTATIONS)

V.E. Neuvazhayev, A.F. Podkorytova
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 3-8.

The paper by Kamchibekov M.D., Meshkov E.E., Nevmerzhitsky N.V., Sotskov E.A. published in 1996 presents the experimental results of studying turbulent mixing evolution on the unstable boundary of the liquid layer, accelerated by compressed gas for cylindrical and plane geometry. The difference in the rate of turbulent mixing zone evolution revealed is explained by geometry effect.
    The paper under consideration interprets the geometric factor effect by k-model of turbulent mixing. The analytical formulae obtained differ from those of the paper mentioned and allow experimental data computing to display the presence of a common constant, defining the mixing intensity. It agrees satisfactorily with the constant defined previously for a plane geometry by other authors (Yu.A. Kucherenko, A.P. Pylaev, K.J. Reed, etc.).
    Computations with TURINB program, implementing ke -model of turbulent mixing were made. A full description of experimental results is obtained at setting initial roughness on the surface of an accelerated shell, the roughness therewith affects substantially a size of a turbulent mixing area within an observed interval of its transformation.

V.B. Vershinin, V.I. Delov, V.N. Sofronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 9-24.

A computational scheme for elastic-plastic flows is described. A theoretical study of numerical computational technique for solving shear streess relief equations is presented. The paper gives the results of numerical calculations compared with exact solutions.

V. V. Gadzhieva, N. V. Gorin, A. V. Kim, S. Yu. Kuzmin, S. N. Lebedev, T. V. Lebedeva, G.V. Orlov, V. N. Pisarev, N. V. Ptitsyna, E.M. Romanova, V. V. Rykovanova, O. V. Stryakhnina, E. A. Sozinov, A. A. Shestakov, V. M. Shmakov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 25-35.

The paper describes the software package SINARA for calculating some emergency processes in a fast reactor. The movement of multicomponent one-speed medium is simulated. Account is taken of elastic and strength properties of materials, linear heat conduction, neutron transport in kinetic and diffusion approximations, nuclei kinetics, energy release, delayed neutrons. The medium model gives consideration for elasticity, plasticity, compressibility, destruction, fusion, evaporation and multicomponent nature. The finite-difference methods for calculating gas dynamics movement and thermal processes are based on implicit ROMB technique, those for calculating kinetic processes - on diamond model of DS_n-method. The calculations of core emergency energy release effect on reactor vessel were carried out. The potentialities of the developed model for heterogeneous failing medium were tested. An estimation was made of the model suitability for computing accidents inside a reactor vessel. Multistage systems of neutron nuclear constants specially developed for computing dynamic processes in reactors with a liquid metal coolant were used. Base tools for arranging parallel computations in local area networks on various types of computers under OS Unix were created. A geometrical decomposition method with the introduction of internal boundary conditions was applied for parallelizing calculations.

O.V. Diyankov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 36-44.

A new approach to the construction of high accuracy order implicit difference schemes is considered. The PDE operators approximation starts from Pade approximation of an exponent. The paper presents a set of difference schemes with oder of approximation in time and spatial variables from one to three. Numerical solutions monotonizing is treated. The results of test calculations compared with exact solutions are given.

G.P. Prokopov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 45-53.

In the case of modelling of nonstationary flows of heat-conductive gas in three-temperature approximation the system of differential equations is completed by state equations for medium components. It is convenient to set them in the form of functions on density and temperature. The condition of thermodynamic equilibrium imposes restrictions on these functions. The construction of state equations for partially ionized plasma is considered. Plasma is simulated by definition of function of ion charge in the form of exponential function on density and temperature.

M.M. Alimov, M.G. Khramchenkov, A.N. Chekalin, N.D. Yakimov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 54-61.

Polution transfer by underground water includes the totality of interconnected processes. The present model of the underground mass transfer is rather complex for computer simulation. In this connection the development of application programs raises the question of testing them.
    The authors have compiled a test bank on the underground mass transfer, including exact analytical solutions for the problems of filtration and (or) migration through advective and (or) dispersive transfer with (and without) physical chemical factors. A brief overview is given of the analytical solutions known for the authors, which can serve as tests for particular components and the whole package of application programs, intended for computer simulation of underground mass transfer. The tests presented are devided into 3 groups: complete tests, including both filtration and migration, the tests for a filtration problem and the tests for a migration problem.

S.I. Sapronov, V.V. Shumilin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2000. No 3. P. 62-67.

The paper describes the principles of message exchange library implementation in MP-3 multiprocessor environment. The library completely meets the requirements of MPI international standard.