ON AN APPROXIMATION OF THE RADIATION TRANSFER EQUATION

Yu. A. Dementyev, Yu. I. Ruzu, I. D. Sofronov, E. N. Tikhomirova
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 3-5.

      A set of single-point algebraic equations is reported, fitting equlibrium nonstationary radiation transfer taking into account grey-matter absorption and isotropic scattering. A cubic octahedron mesh is used. The scheme is conservative, stable, and, mainly, second-order accurate. The approximate solution is characterized by non-increasing amplitude. An array-processor computer may be effectively used. A disadvantage of the scheme cons its in severe time-step 1imi tat ions.

V. N. Ogibin, A. I. Orlov
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 6-9.

      A "majorating cross-section" approach is proposed for solving a transfer equation with Monte-Carlo method. Variants of the approach and associated algorithms of simulating neutron trajectories are considered.

V. I. Igrunov, L. N. Simagin
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 10-13.

      Possibility of using the BESM-6 computer with a tape drive is considered without employing fast directions. The scheme of the channel is provided allowing information exchange between BESM-6 and other types of computers (ES, MINSK-32, ets.) with aid of MT. While exchanging via this channel the BESM-6 runs only under a channel control routine.

A. D. Pantyushin, P. M. Rannev, Yu. I. Samsonov
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 14-16.

      Some questions concerning IZOT-1370 (SM-5400) exchangeable disk drive operation are considered. In particular, we propose variants of replacing failed components which have no domestic analogues. Efforts to achieve disc drive interexchangeability are discussed.

V. E. Neuvazhayev, V. G. Yakovlev
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 17-25.

      A semiempirical model of gravitational mixing is considered with eguation for turbulent kinetic energy. The model includes three constants. Model properties are investigated on self-similar solution for incompressible fluids. Linear dependence of mixing effective width on Atwood number is ascertained. A finite-difference method of solution of equations is given for general, non-self-similar case. A solution is derived for compressible gases with mixing for an automodel problem with two energy release regions.

Yu. A. Dementyev, R. F. Mashinin, V. I. Nagorny, V. G. Rogachov, E. N. Tikhomirova
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 26-28.

      An integral equation is solved describing nonsta- tionary energy transfer by radiation through a region of negligible optical width, retardation and shading being taken into account. A numerical solution technique is qiven based on mesh description of the process. Energy portions are calculated the computational cells exchange with on the radiating surface each time step. Examples of model calculations are supplied.

A. T. Sapozhnikov, A. V. Pershina
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 29-33.

      Computationally-economic interpolation equation of state is proposed for the energy range 0, ~200kj/g and density range ~10^-3, 1,5ρ_ok, where is pressure at S.C. The economy is due to piecewise-analytical representation form of the equation ef state and to using only polinomial and fractionary-rational functions in computational formulas. An approach to select optimal parameters of the equation of state is discussed and their values are given for aluminium, copper, and lead. Thermal characteristics calculated by the equation of state are compared with experimental data shock compression, thermal expansion, and evaporation.

A. V. Nikiforova, V. A. Shumilin
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 34-36.

      Mathematical propositions, general organization, and capabilities of LOM(I) routine intended for evaluating 2D critical parameter λ in multigroup isotropic approximation are given. The routine is written for ES-1060 Computer in PL-1 language. The paper also contains calculations for axisymmetric λ systems and comparison of them with other results.

V. A. Barannikov, A. A. Kibkalo, N. M. Mikiychuk, S. A. Firsov
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 37-40.

      The paper gives a brief description of ES-8504 user point software (AP-4), consisting of cross - system for AP-4 running on the base of BESM-6 computer, providing a full working cycle for creating and debugging routines for AP-4 on BESM-6, and of operating system AP-4 permitting to use the point in job teleprocessing system as a remote input - output package node.

V. A. Zhmaylo, A. A. Sadovoy, N. M. Chulkov
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 41-46.

      Solution of a model problem of cooling gas, which fills up a half-space, due to heat transfer by nonequilibrium radiation is expressed in quadratures. Conditions are analysed concerning transition to equilibrium cooling mode described by heat - transfer equation.

A. V. Rudkevich, V. G. Dvoretsky, V. B. Ivanov, B. A. Kanashov, Yu. V. Markov, V. M. Rayetsky, T. A. Temnoyeva
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 47-56.

      Basic architecture principles are given for information system providing prompt access to facts describing experimental conditions and results of reactor material testing. An approach is proposed for modelling a material field; methods of receiving answers to requests and software for user-system dialogue organization are described.

A. V. Ruddkevich, T. A. Temnoyeva, Yu. V. Markov
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 57-65.

      A way of knowledge representation in a factograhic system of information retrieval is presented based on using semantic networks, indefinite values, and so- called modal functions. On the basis of the suggested approach complex objects vehavior in time is simulated, deductive derivation is given, conclusions are made concerning ability of realization of varions combinations of facts. A way of knowledge representation is described using semi-relational data base which relations are presented by disordered flat files. Time of answer retrieval for request is analysed and recomendations for its optimization are given.

S. A. Stepanenko
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 66-71.

      A class of non-uniform codes is proposed for information "compressing allowing minimization of coding and decoding algorithm complexities. Estimates of decoding algor thm cemolexities are obtained, in the capacity of which logic algorithms are used.

K. N. Baryshnikova, V. V. Zmushko
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 72-75.

      An algorithm of solving heat conduction equation is considered for separate regions. An inconditionally stable, economic difference scheme is constructed on the basis of run method. The maximum principle of flow is proved. The scheme may be applied to solve diffusion problems, especially two-dimensional ones with complex geometry.

N. Yu. Bakayev
VANT. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki. 1984. No 2. P. 76-79.

      A convenient form of solution of direct problem of electromagnetic disturbance spread in homogeneous conducting media is considered for the class of causal pulses.