Issue No 4, 2005 |
GEPARD TECHNIQUE FOR SIMILATION OF CONNECTED AEROHYDROELASTICITY PROBLEMS
G. V. Gorbenko, Yu. V. Yanilkin, A. V. Gorodnichev, A. A. Smolyakov, E. A. Golovko, V. Yu. Kolobyanin, P. B. Loginov, A. S. Razumkov, V. I. Tarasov, I. N. Chistyakova, N. A. Khovrin
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 3-14.
The paper describes GEPARD technique presenting connection between EGAK and DRACON techniques and TREK and DRACON techniques and designed for solution of complex two- and three-dimensional problems of polyphase medium dynamics including dynamics of solids under gas-dynamic (hydrodynamic) loading (the so-called connected aero- and hydroelasticity problems). Peculiarities of the mentioned techniques and principles of connection organization between them in consistent and multiple-processor modes are presented. Calculation results of the techniques taken separately as well as in connection mode are compared with experimental data.
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| TECHNOLOGY OF PREPARATION OF GROUP MACROSCOPIC CONSTANTS AND PROCEDURE OF THEIR REFINEMENT IN CALCULATING NEUTRON TRANSPORT PROBLEMS | A. N. Grebennikov | , | | , | A. V. Alekseev | , | S. V. Mzhachikh | , | N. A. Krut`ko |
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 15-24.
The paper describes the system of constant assurance of neutron-physical calculations, particularly in solving non-stationary problems of neutron transport and problems of energy-release in group kinetic approximation developed in RFNC-VNIIEF. The essence of the system lies in application of a closed technological chain of data processing: including work with libraries of estimated neutron data, working-out of recommendations for application of different libraries of constants for problems of different kinds, calculation of group constants and their refinement while calculating non-stationary problems of neutron transport.
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| SHOCK-FREE COMPRESSION OF SYMMETRIC PRISMES WITH ISOTHERMAL GAS O. B. Khairullina
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 25-37.
The problem of computation of gas-dynamic parameters for shock-free compression of a gas tetrahedral infinite prism with a cross square section is considered. The solution is constructed using characteristic series. For isothermal gas, the exact expression of gas velocity potential and the form of compressive piston is obtained according to the definitely given law of prism edge movement on the plane of symmetry. The solution describes the process of full shock-free collapse of gas into a straight line. The gas-dynamic magnitudes behavior is investigated for this compression.
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| METHOD OF CONTACT BOUNDARY COMPUTATION FOR IRREGULAR POLYHEDRAL GRIDS IN TIM TECHNIQUE S. S. Sokolov, A. V. Yalozo
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 38-45.
Development of a simulator allowing to calculate contact interaction of solids on irregular polyhedral Lagrangian grids in three-dimensional approximation is considered in the paper. Contact boundary of solids is described with the help of triangulated surface obtained by triangulation of solids surfaces used in TIM technique calculations. Specially developed algorithms are used to form and keep this surface. Algorithm of inelastic collision is posited in calculation algorithm for interaction of two triangular surfaces. The results of test calculations showing efficiency of calculation technique for contact boundary movement on methodical and test problems are presented. The developed algorithm for calculation of contact boundary movement allows to expand the class of simulated problems in 3D-statement in TIM technique.
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| CONSTRUCTION TECHNIQUE FOR A POLYHEDRAL SHEET GRID ON THE BASIS OF A MULTANGULAR IRREGULAR GRID A. A. Voropinov, S. S. Sokolov, A. I. Panov
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 46-52.
Construction technique for an irregular three-dimensional grid on the basis of a two-dimensional regular quadrangular grid or an irregular multangular grid is described. Construction of a two-dimensional grid is realized by partitioning of domains into subdomains, filling of each domain by a grid, overlapping of transformations and joining of subdomains into one countable domain. Construction of a three-dimensional grid is carried out per sheet by relocating of a two-dimensional grid along a specified vector in space or by its turning around a specified axis. Both the initial two-dimensional grid and the grid obtained after calculating of initial movement stage using two-dimensional technique may serve as an initial grid. Both techniques allow to construct grids for several countable domains.
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| RECONSTRUCTION OF TOROIDAL PLASMA BOUNDARY USING VIDEO IMAGE D. P. Kostomarov, A. A. Lukianitsa, F. S. Zaitsev, A. B. Trefilov, V. V. Zlobin
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 53-68.
A new algorithm for plasma boundary reconstruction using video filming data is suggested. The problem of camera calibration is solved. A priori and a posteriori estimations of algorithms discrepancy are obtained. Sufficiently high accuracy of solution of the ill-posed inverse problem is demonstrated. The new method of reconstruction of space position of a curve with photo image or its analogues can be used for a wide class of image processing problems.
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| APPLICATION OF RRM TECHNIQUE FOR CALCULATIONS IN EGAK AND TREK TECHNIQUES Yu. V. Yanilkin, V. Yu. Kolobyanin, I. N. Chistyakova, M. Yu. Eguzhova
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 69-79.
Calculation results of EGAK and TREK techniques applying different methods of approximation of convective terms of equations (donor technique, RRM technique and concentration technique) are given. All calculations are conducted in Euler statement. The paper presents comparison and analysis of results obtained in calculations showing that concerning accuracy RRM technique has doubtless advantage over donor technique, and over concentration technique in some cases. Algorithm for combination of RRM and concentration techniques keeping their best features is suggested.
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| OPTIMAL COOLING OF HEATED THIN-WALLED SYSTEMS UNDER HEAT-REFLECTION BREAKDOWN N. I. Obodan, N. A. Guk
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 80-85.
Behavior of a thin-walled system (plate) located in a thermal field and subjected to cooling after heat-reflection breakdown is considered. Under forced cooling a residual stress field appears in a system which can bring both to local collapse in the neighborhood of a defective part and to plate splitting in zones distant from breakdown spot. To prevent these effects it is necessary to define cooling law optimizing the process with relation to toughness and fastness assurance. A mathematical model is presented by thermoelasticity equations with additional deformations. Solution of a heat conductivity problem in a finite element form is used to describe temperature field. A problem of cooling control is formulated; optimal control is shown to be a step function having a finite number of break points. Construction algorithm for a cooling function is presented. Calculation results are given: cooling of a plate with the use of a construction algorithm for a cooling control function is shown to lead to appearance of residual stress of an essentially lower amplitude.
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| TEST ANALYTICAL SOLUTIONS OF A BRINE TRANSPORT EQUATION IN A WATER-BEARING STRATUM V. M. Konyukhov, A. N. Chekalin
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 86-97.
Analytical solutions of a one-dimensional equation of hyperbolic type describing brine filtration are made. Test problems containing basic specific features of desired solution are considered such as appearance, evolution and interference of saturation jumps arising on lines of discontinuity of absolute permeability; moving of saturation jumps with variable amplitude downstream the filtration flow as well as upstream; formation of motionless pollution core on the boundary of absolute permeability break in downstream filtration flow; dependence of boundary conditions describing modes of brine inflow into the porous medium from solution inside filtration area.
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| THE PUZZLE OF GODUNOV METHOD G. P. Prokopov
VANT. Ser.: Mat. Mod. Fiz. Proc.. 2005. No 4. P. 98-101.
In Godunov method for computational solution of gas-dynamic problems much success is achieved owing to the use of the additional entropy conservation law for smooth solutions and the postulate of its non-decrease on breaks. The question arises as to whether all the authors declaring Godunov-type methods pay proper attention to it.
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