DIFFERENCE GRIDS AND COMMUTATION NETWORKS

I.D. Sofronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 12-19.

      At numerical solution of computational physics problems appreciable is the role of the difference grid which determines interactions among thousands or millions of problem elements.
      In recent years most labor-consuming problems have been solved on multi-processor computers containing several hundreds or thousands of processor elements connected with a commutation network. The paper studies question arises about the effect of similarities and differences in the difference grid and commutation network architectures on the equipment performance.

R.M. Shagaliev, V.A. Shumilin, A.V. Alekseev, I.M. Belyakov, V.V. Evdokimov, O.A. Zvenigorodskaya, A.N. Moskvin, N.P. Pletenev, L.P. Fedotova
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 20-26.

      The paper gives a brief description of SATURN-3 codes, designed for numerical solution of 2D and 3D stationary and nonstationary linear problems of neutron transfer and nonlinear problems of energy transfer (by photons, ions and electrons).
      The paper also states principal methodical propositions, forming the basis of SATURN codes. The main physical-and-mathematical models are formulated, the statements of mathematical techniques, used for solving some classes of multidimensional problems are described. Computed data for test problems are presented.

I.D. Sofronov, B.L. Voronin, S.I. Skrypnik, A.N. Bykov, A.G. Kozub, O.I. Butnev, R.A. Veselov, A.M. Erofeev, A.V. Alekseev, A.A. Kazarin, N.V. Shumilina, A.V. Urm, E.V. Shaporenko, O.A. Pronina
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 27-31.

      Relying on review of early papers as well as on outline of basic principles, methods and algorithms a present state of RAMZES and RAMZES-KP is presented.
      Eulerian and Lagrangian technique and RAMZES codes are meant for computing multidimensional (2D and 3D) gas dynamic motions with regard to heat conduction and other attendant processes. RAMZES-KP complex implements RAMZES technique with concentrations and represents a program system of new generation, allowing to compute complicated 2D and 3D problems on multiprocessor systems.

S.M. Bakhrakh, V.F. Spiridonov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 32-36.

      The problems are discussed of localizing interfaces, not coinciding with computational grid lines. This brings up two main problems: computing quantities in the grid meshes, containing several agents, and computing convectional flows from such meshes. The principles of solving the above problems, used in LEGAK technique are presented. Those principles allow computing interfaces with large distortions. The examples of the above problems computation are offered.

I.D. Sofronov, O.A. Vinokurov, V.V. Zmushko, F.A. Pletenev, T.B. Izmaylova, L.F. Potapkina, P.V. Rybachenko, N.A. Ryabikina, N.V. Sokolova, L.Ya. Trofimova
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 37-41.

      The paper describes MIMOZA complex as of 1999. Test calculations and their comparison with other programs and experimental data are cited. A description is given of 2D spectral computations of asymmetric targets, examined in the experiments on x-rays targets illumination on “ISKRA-5” unit. Computed results were compared with experimental data. The calculated neutron yields and generation time were demonstrated to agree with experimental data well.

I.D. Sofronov, V.I. Delov, L.V. Dmitrieva, A.Yu. Artem´ev, V.I. Budnikov, V.B. Vershinin, N.A. Dmitriev, N.V. Korepova, D.M. Linnik, E.V. Malinovskaya, O.O. Murugova, V.V. Sadchikov, R.Z. Samigullina, S.Yu. Suslova, E.S. Khiteva, Yu.D. Chernyshev
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 42-50.

      D technique brought to the notice is based on one of the oldest 2D Lagrangian gas dynamic technique and successfully used at RFNC-VNIIEF up to now. The paper is aimed at reflecting the main steps of its development and present state.

V.V. Rasskazova, I.D. Sofronov, V.N. Motlokhov, A.N. Shaporenko, A.Yu. Eremenko, P.A. Rasskazov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 51-56.

      The paper describes DMK-2 and DMK-3 complexes designed for computing 2D and 3D gas dynamics problems with regard to strength properties of a substance, heat conduction, detonation of explosives and transfer of solid particles, involved in motion by medium. They are started from the techniques based on regular and irregular Lagrangian difference grids, which can be used simultaneously in different parts of solution domain of the problem under consideration.

S.G. Volkov, B.M, Zhogov, I.D. Sofronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 57-63.

      Free-Lagrangian MEDUZA technique uses irregular space grid and varying template for choosing neighbours to integrate numerically differential equations of gas dynamics. Numerical solution of an equation of heat conduction uses an implicit difference scheme solved by an iterative method. A space gas dynamic grid is used for numerical solution of an equation of heat conduction and gas dynamics and heat conduction are computed step in step. MEDUZA technique has the following peculiarities: use of local grid modifications and mixed cells for simulating interfaces. In the course of the technique use the initial algorithms of local grid modifications and mixed cells calculations were constantly being upgraded. The descriptions of standard and upgraded algorithms are reported. The computations displaying the technique potentialities are exemplified.

A.K. Zhitnik, Yu.K. Kochubey, A.N. Subbotin, E.N. Donskoy, V.N. Eltsov, N.V. Ivanov, A.I. Morenko, L.Z. Morenko, A.B. Ronzhin, V.I. Roslov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 64-67.

      The appearance and development of Monte Carlo method at VNIIEF are briefly outlined. The means of up-to-date programs, using Monte Carlo method and types of the problems solved with them are presented.

I.D. Sofronov, B.P. Tikhomirov, S.V. Bazhenov, A.A. Bazin, V.V. Gorev, N.S. Darova, Yu.A. Dement´ev, Yu.N. Deryugin, I.F. Kazakova, V.M. Melnikov, V.F. Mironova, P.I. Pevnaya, P.A. Perepelkin, L.I. Sizova, G.I. Skidan, E.N. Tikhomirova, N.I. Yurina
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 68-75.

      A numerical method for solving an integral equation of radiation in spectral formulation is discussed. A study was made of diffusive-vacuum model for computing 2D and 3D nonstationary problems of heat transfer in closed optically heterogeneous systems. A difference method for solving 2D problems of radiation diffusion is presented, based on the improved model of radiant heat conduction. The paper gives some difference schemes for solving 3D problems of heat conduction, implemented in codes.

A.N. Grebennikov, V.N. Ivannikova, N.A. Krut´ko, G.G. Farafontov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 76-82.

      A brief overview is given of present state of constant support system for neutron-physical computations, developed at mathematical department of RFNC-VNIIEF.

I.A. Adamskaya, A.I. Prokof´ev, A.I. Sokolova, V.N. Sofronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 83-87.

      The paper gives a review of some codes for solving one-dimensional gas dynamics problems, as well as codes for computing critical parameter of transport equation, developed at mathematical department of RFNC-VNIIEF.

Yu.V. Yanilkin
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 88-94.

      A review is given of the methods, developed within complexes EGAK and TRAK and intended for simulating 2D and 3D flows of multicomponent compressible medium with large distortions, including turbulent stirring stage. The results of numerical problem research are presented.

G.I. Voronov, I.V. Gorev, N.I. Leonova, E.A. Luneva, G.S. Osenkova, Z.V. Suraeva, A.V. Timon´kina
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 95-98.

      A brief description of the development and the latest version of the software for computing thermodynamic functions of equations of state and mean photon paths of EOS-OP Package on PCs is presented.

I.D. Sofronov, V.M. Kukhtin, Aleksey A. Kibkalo, Yu.G. Bartenev, A.I. Lukin, N.N. Abramov, E.L. Shnepov
VANT. Ser.: Mat. Mod. Fiz. Proc. 1999. No 4. P. 99-103.

      A description and grounds are given for basic principles, laid at designing multi-access computer network at RFNC-VNIIEF. A network structure and a brief description of its main components are given.