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RUSSIAN FEDERAL
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ALL-RUSSIAN RESEARCH INSTITUTE
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Issue No 3, 2016


THE DIFFERENCE SCHEME APPROXIMATION VISCOSITY AND SIMULATIONS OF VISCOUS FLUID FLOWS

Yu. V. Yanilkin, O. O. Toporova, A. L. Stadnik, L. E. Korzakova
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 3-17.

The paper briefly describes the original equations and difference scheme used for the simulation of viscous and inviscid gas dynamic multimaterial flows in Eulerian variables with the EGAK code. A theoretical estimate of the scheme viscosity of the difference scheme used in the code is presented. Test computations have been carried out and they demonstrate the validity of using the theoretical estimate of the scheme viscosity in simulations for the particular problems.


Key words: molecular viscosity, scheme viscosity, Eulerian method, the EGAK code.
A NUMERICAL METHOD OF FINDING THE HYDRAULIC CHARACTERISTIC OF A NONSTATIONARY FLOW OF VISCOELASTIC FLUID IN A WELL

Kh.M. Gamzaev
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 18-25.

The nonstationary motion of a viscoelastic circulating fluid in a drilled well is considered. To describe the process, it is suggested to use a mathematical model built on the basis of a rheological model of Maxwellian viscoelastic fluid. The problem of finding the hydraulic characteristic of the circulating fluid flow has been formulated within this model. The problem is reduced to an inverse problem of reconstructing the time dependence for the hyperbolic equation’s right-hand part. A difference analog to the inverse problem has been developed and a computational algorithm has been offered to solve the resultant system of difference equations.


Key words: viscoelastic fluid, washing out of well, hydraulic characteristic, inverse problem.
LOGOS CODE PACKAGE: THE METHOD OF SOLVING THE STATIC STRENGTH PROBLEMS FOR THIN-WALLED AND FRAMED STRUCTURES ON THE BASIS OF THE SOLID-SHELL TECHNOLOGY

R. A. Barabanov, D.Yu. D’yanov, I.I. Kanygin, V.F. Spiridonov, E.A. Filimonkin, K.V. Tsiberev
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 26-36.

A technology of simulating the structure deformation process by expanding the structural finite elements (shell and beam elements) to obtain solid elements of continuum (hexahedrons, triangular prisms) has been developed and implemented in the static strength module of the LOGOS code package. This technology allows simulating the nonlinear deformation of thin-walled structures with shell and beam elements owing to the earlier implemented capabilities for solid elements. The basic procedures and algorithms of the implemented method are described, results of test simulations of nonlinear problems with regard to geometrical nonlinearity are presented and compared with the available benchmark solutions.


Key words: LOGOS code package, static strength, the finite element method, nonlinear straining, the solid-shell technology.
ON A POSSIBILITY ОF HOMOGENEOUS PORE ORIGINATIONA IN A GRAIN-BOUNDARY REGION UNDER THE IMPACT OF POST-CASCADE SHOCK WAVES

A.V. Markidonov, V.D. Starostenkov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 37-46.

The molecular dynamics studies demonstrate that a directed flux of vacancies resulting in the origination of pores due to tensile stresses behind the shock wave front occurs under the impact of post-cascade shock waves. Pores originated at the grain-boundary dislocations and their further displacement under the impact of shock waves cause the growth of one grain owing to the absorption of the neighboring grain. The described phenomena are observed at temperatures, which are insufficiently high to start the diffusion process.


Key words: computer simulation, the molecular dynamics method, the embedded atom method, shock wave, defects, vacancy, pore, grain boundary, stair rod dislocation.
THE STRUCTURE OF 3D STATIONARY ISOBARIC DUAL WAVES IN AN IDEAL INCOMPRESSIBLE FLUID.
PART1. REDUCTION OF THE GOVERNING EQUATION SYSTEM

V. E. Shemarulin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 47-61.

The study of the structure of isobaric (inertial) flows of an ideal incompressible fluid continued. Non-trivial (inconstant) isobaric flows fall into two classes: the rank 1 flows (simple waves) and the rank 2 flows (dual waves). In the previous paper the author comprehensively described the structure of simple waves – both the 2D nonstationary and 3D stationary waves.
The present paper consisting of 2 parts describes the structure of 3D stationary isobaric dual waves. In Part 1 of the paper a governing system of functional equations implicitly defining isobaric 3D stationary dual waves is reduced to an equivalent system, which is more convenient for studying. In the next part, it will be shown that the reduced equation system solutions have a simple geometric structure and a variety of local solutions to the system (the main structural components, which assemblies represent all dual waves considered here) will be explicitly described.


Key words: isobaric flows, 3D stationary dual waves, a governing system of functional equations, a reduced system.
THE PROMISING HYBRID TOPOLOGY KNS FOR INTERPROCESSOR COMUNICATION SYSTEMS ON THE BASIS OF SMPO-10G

V. G. Basalov, A.A. Kholostov
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 62-69.

The paper describes the hybrid topology KNS for communication networks of multiprocessor systems on the basis of SMPO-10G system for interprocessor communications. The adaptive routing algorithms developed for this topology are described, which allow building the shortest message paths free of interlocking states and provide a high level of fault tolerance of the communication network and its balanced loading. Comparative analysis of the main architectural and technical characteristics of most popular topologies used to create communication networks for high-performance multiprocessor computing systems is presented.


Key words: multiprocessor computing system, communication networks, interprocessor communication system SMPO-10G, hybrid topology KNS, adaptive routing algorithms, virtual channel.
CONTROL OF FIBER-OPTIC LINK DAMAGES IN DISTRIBUTED INFORMATION-COMPUTER NETWORKS USING THE INTEGRAL REFLECTOMETRY AND DIRECT DETECTION METHODS

K. I. Balashov, V. V. Shubin
VANT. Ser.: Mat. Mod. Fiz. Proc. 2016. No 3. P. 70-79.

Results of the development of the way of controlling damages in a fiber-optic link of distributed information-computer network using the integral reflectometry and direct detection methods are presented. It is demonstrated that in time domain the optical reflectometry method is preferable in comparison with the direct detection method. The optical reflectometry method limitation, in time domain, consists in a weak waveform of backward scattering leading to delay in decision making. It is shown how these shortcomings can be removed by using the integral reflectometry method. To improve reliability and increase the speed of operations, it is suggested to use the integral reflectometry method in combination with the direct detection method within one controlling device. The calculation of parameters and structural diagram of the device are presented.


Key words: fiber-optic link, distributed information-computer network, fiber-optic damages, the integral reflectometry method, the direct detection method.
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