Issue No 1, 2004 |
APPLICATION OF THE PIECEWISE PARABOLIC METHOD TO CONVECTIVE FLOW CALCULATIONS USING LAGRANGIAN-EULERIAN GRID
S. M. Bakhrakh, I. Yu. Bezrukova, S. N. Pronevich
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 3-11.
A piecewise parabolic method to compute convective flows is implemented within LEGAK complex for computing time-dependent multi-component medium flows in Lagrangian-Eulerian setting. The computation of test (shock wave movement) and methodical (ellipsoid dispersion, growth of gas interface instability as a shock passes through) tasks showed the efficiency and availability of a piecewise parabolic method for enhancement of calculations accuracy.
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| NUMERICAL STUDY OF TURBULENCE MIXING FOR RICHTMYER-MESHKOV INSTABILITY PROBLEM N. V. Zmitrenko, M. E. Ladonkina, V. F. Tishkin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 12-27.
A numerical study is made of dynamics of hydrodynamic instability growth and turbulence appearance on insulating gas-air interface for conditions corresponding to experiments on the shock tube. Computations were run with NUT complex, including parallel code version using 270 processors. The relation between turbulence characteristics and initial perturbations spectrum is established. It is shown that the dependence of E(q) ~ q-11/3, observed earlier in other computations and experiments is valid for spectral density of the energy E(q) in the dissipation region.
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| NON-UNIQUENESS OF RAREFACTION SHOCK WAVES: THE ROLE OF INTERPHASE KINETICS Yu. A. Bondarenko, V. N. Sofronov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 28-46.
The rarefaction wave data available from literature relies upon the assumption that any discontinuous solutions of gas-dynamic equations should be derived by disappearing viscosity method. In this study the rarefaction wave properties were gained analytically for the case of gas-dynamic equations regularization using interphase kinetics. It is proved that if equations-of-state for two pure phases do not overlap, then rarefaction waves, obtained with the artificial interphase kinetics coincide with those obtained with the disappearing viscosity. If equations-of-state for pure phases do overlap these shock waves differ essentially. It is confirmed by 1D gas-dynamic calculations.
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| SMOOTHING ALGORITHMS FOR HIGH-FREQUENCY PERTURBATION OF THE VELOCITY FIELDS AS APPLIED TO MULTI-CELL COMPUTATIONS ON A MULTIPROCESSOR S. M. Bakhrakh, V. V. Borlyaev, N. A. Volodina, M. O. Zaitseva, A. D. Kovaleva, O. N. Kulygina, L. A. Ryabchun
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 47-54.
The paper centers on studying several types of smoothing operators for high-frequency perturbations within LEGAK-2D complex as applied to multi-cell computations. A smoothing operator by the fourth-order differences with weighting factors is ordinary used within LEGAK-2D programs. This operator was modified with regard to all defects and entered into LEGAK-2D complex. The smoothing operators of physical viscosity type and Chen smoothing operator are also entered into this complex. The results of test computations using proposed smoothing operators are presented. The recommendations for their use are given.
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| ASYMMETRIC FLOW ABOUT A CONE F. A. Maksimov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 55-62.
The paper presents results of the simulation of flow about a cone at the angle of attack with generation of asymmetric flow pattern on the leeward side. The simulation uses the Navier-Stokes equations in the thin layer approximation with the method of establishment.
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| SOME UNCERTAINTY EVALUATION RESULTS FOR ROUND-OFF COMPUTATIONS EXAMPLEFIED BY A LINEAR ALGEBRA APPLICATION A. S. Sukhikh, V. I. Fedianin, V. F. Yudintsev
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 63-69.
A 2D heat conduction application with the known exact solution was used as an example for fitting two formula parameters for estimation of relative round-off computation error.
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| DEVELOPMENT OF VISUALIZATION TOOLS FOR PARALLEL COMPUTATING SOFTWARE. PARALLEL PROGRAM OPTIMIZATION V. L. Averbukh, A. Yu. Baidalin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 70-80.
The paper constitutes a review of current status of software visualization for parallel computations and description of the authors projects in the area of developing visual performance tuning for the domestic parallel programming system DVM.
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| IDENTIFICATION OF MULTIDIMENSIONAL NON-STATIONARY DYNAMIC OBJECTS WITH KALMAN FILTRATION METHOD V. M. Ponyatsky
VANT. Ser.: Mat. Mod. Fiz. Proc. 2004. No 1. P. 81-86.
The problem of dynamic processes identification from measured information signals is studied. The Kalman filtration method is used for model parameters estimation. The results of real processes testing and identification are presented.
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