Numerical simulation of viscous flow around a system of bodies on the basis of the Navier-Stokes equations in stream function-vorticity variables

A method of numerical solution of the Navier-Stokes equations in stream function-vortex-pressure variables is suggested to be used in simulating a nonstationary, nonsymmetric flow of a laminar incompressible viscous stream around a pair of rotating cylinders in a channel. Results of calculations which illustrate application of the method under different conditions of flow around bodies are presented. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 118–125, September–October, 2006.     

Explosive fracture of closed cylinders

We present the results of numerical simulation of the process of fracture of thick-walled elastoplastic cylinders with bottoms caused by the explosion of a blasting charge placed inside the cylinders. We show that the influence of the scheme of explosive loading on spalling effects in the walls of the cylinders is significant. Scientific Research Institute of Applied Mathematics and Mechanics, Tomsk, Russia. Translated from Problemy Prochnosti, No. 4, pp. 44–51, July–August, 1997.     

Comparative analysis of turbulence models

A comparative analysis is performed for a complete locally anisotropic turbulence model of the second order and existing turbulence models. The comparison draws on experimental data, data of a direct numerical simulation of the nonstationary Navier-Stokes equations for a developed channel flow and a uniform channel flow with a constant velocity shift, and results for turbulence damping behind a grid. The K-ɛ model and the quasi-isotropic turbulence model are shown to have marked disadvantages, especially in describing turbulent flows with a high degree of anisotropy of pulsatory motion. Use of a locally anisotropic turbulence model improves the accuracy of determining Reynolds stresses. Consideration is given to the advantages and disadvantages of the turbulence models discussed. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 328–339, March—April, 2000.     

Heat conduction of orthotropic half-space for mixed discontinuous boundary conditions

The nonstationary temperature field in a half-space heated across a circular region with a known radius r=R over a surface z=0 of a semibounded body is found Outside the circular region r>R the initial temperature ϕ(r, 0, τ)=T(r, 0, τ)−T₀=0 is maintained on the surface z=0. Particular regularities of development of nonstationary temperature fileds along the axisr=0, z≥0 and over the surface z=0, 0≤r<R are given. Belarusian State University, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 826–833, September–October, 1996.     

The use of an explicit method of identifying objects to solve problems of nonstationary heat conduction

The theoretical principles of an explicit method of identifying multidimensional objects with nonstationary thermal conductivity are described. The solution of problems of measuring nonstationary heat flux and thermal conductivity in the range λ = 0.03–800 W/(m·K), the thermal conductivity of one of the materials of a double-layer system, the temperature dependence of the thermal conductivity, and the combined “thermal conductivity and volume heat capacity” are presented. The results of investigations on thermal models are given. __________ Translated from Izmeritel’naya Tekhnika, No. 6, pp. 32–38, June, 2008.     

Determination of filtration parameters of a layered bed using data of unsteady liquid inflow to a well

A computational algorithm based on the theory of ill-posed problems is proposed for evaluating filtration parameters of a layered bed using the results of nonstationary hydrodynamic investigations of vertical wells. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 128–130, May–June, 2006.     

Nonstationary radiation-gasdynamic model of a laser-plasma accelerator

Based on the system of two-dimensional axisymmetrical continuity equations, Navier-Stokes and energy equations, and the equations of selective heat radiation transfer, a computational model is constructed and conditions of unsteady subsonic flows in a cylindrical channel of a power unit of the laser-plasma accelerator type are investigated. The governing parameters of the model are calculated, at which numerical solutions can be obtained to describe steady laminar gas flow in the neighborhood of the region of heat release, nonstationary oscillatory motions, and nonstationary vortex motion. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 174–179, January–February, 2000.     

On the theory of thin bodies

It is shown that, in accordance with the law of plane sections representing the basis of the theory of thin bodies, two analogies are true: a nonstationary analogy and a stationary one. Within the framework of the stationary analogy, a new-type expansion reducing a three-dimensional problem to a stationary two-dimensional one is introduced. The asymptotic conditions of validity of the stationary and nonstationary analogies were determined and the boundary-layer conceptions for both cases were compared. Solutions of the internal and external problems on a two-dimensional flow in a narrow zone were obtained in the closed form. An asymptotically correct mathematical model of a flow in a film is proposed. The stationary and nonstationary analogies for a swirling flow around a body and a flow around a rotating body were determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 45–54, September–October, 2007.     

Thermal conductivity and quasihomogeneity criterion of disperse materials

We suggest a method of numerical calculation of the effective thermal conductivity and the time for establishing quasihomogeneity of disperse materials. The method is based on the principle of generalized conductivity realizable within the framework of a nonstationary thermal problem. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 3, pp. 441–446, May–June, 1998.     

The first critical heat-flux density of kerosene in stepwise and steady-state releases of heat

Experimental results on determination of stationary and nonstationary first critical densities of heat fluxes for the TS-1 hydrocarbon fuel are presented. As a consequence of the investigations carried out in a wide range of subcoolings and pressures, it has been established that for kerosene, just as for water, hydrogen, and helium, the first nonstationary critical heat-flux density q_cr.1n coincides with the stationary one q_cr1. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 57–60, November–December, 2006.     

Nonstationary flow of solutions of flexible-chain polymers in a porous medium

Aqueous solutions of polyethylene oxide have been studied under the conditions of nonstationary longitudinal flow. The investigations have confirmed the deviations from Darcy’s law according to the mechanism the basis for which is provided by the concepts of a strong strain action of the hydrodynamic field on coiled macromolecules. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 123–127, September–October, 2005.     

Unsteady heat transfer in a system of three coaxial finite cylinders

An integral transformation with the aid of which a solution of the problem of unsteady-state heat transfer in a system of three coaxial finite cylinders with different boundary conditions on their surfaces depending on space and time is presented. Each of the cylinders evolves heat of a certain intensity, depending on time and coordinates. A numerical solution of one variant of the boundary conditions is given and illustrated by figures. The method of transforming the solution of the problem with other boundary conditions is shown. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 140–148, January–February, 2007.     

Analytical methods of investigation of the thermal state of a region with a moving boundary under the conditions of nonstationary heat transfer to the external medium

An analytical method of solution of combined problems of nonstationary heat conduction for a region with a boundary moving according to a known law and with a time-variable coefficient of heat transfer is developed. The idea of splitting the kernel of the obtained generalization of a singular integral Fourier transform with respect to a space variable provides a basis for the method. Theoretical results are used in mathematical simulation of heat transfer processes in the region with a moving boundary under the conditions of nonstationary heat transfer to the external medium. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 125–130, January–February, 2000.     

Conductive-convective drying installations: Problems and calculation

We present a procedure to calculate multicylinder conductive-convective drying installations and equations to determine the temperatures of a paper strip when on cylinders and off them. Dependences are obtained to calculate the intensities of moisture evaporation and reduction of the moisture content of fibrous woodpulp paper materials over corresponding portions, as well as a formula to calculate the relationship between evaporated moisture on cylinders and off them in the “on a drying cylinder-off a drying cylinder” cycles. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 6, pp. 1000–1005, November–December, 1998.     

Estimation of the nonstationary variance of an acoustic signal

A model of the residual fluctuations of a primary-processing subsystem is proposed, on the basis of which the noise immunity of an algorithm for estimating nonstationary variance is investigated. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 57–60, April, 2007.     

Unsteady frictional heating of projections of microirregularities of a sliding contact

A nonstationary mixed problem of heat conduction that models the process of frictional heating in sliding of rough surfaces is solved. I. Franko L'vov State University, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 768–772, September–October, 1996.     

Exact solution of the problem of nonstationary heat conduction for two semispaces in nonideal contact

An exact solution of the nonideal-contact problem of nonstationary heat conduction for two semispaces with constant initial temperatures has been obtained. It is shown that the problem at hand is similar in thermal action to the third boundary-value problem for a semispace bordering on a medium of constant temperature that has a certain value. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 86–87, September–October, 2006.     

Method of paired integral equations withL-parameter in problems of nonstationary heat conduction with mixed boundary conditions for an infinite plate

For solving a nonstationary equation of heat-conduction in cylindrical coordinates with mixed discon-tinuous boundary conditions prescribed on one of the surfaces (z=0) of an infinite plate, a method of paired integral equations with L-parameter is used. Moreover, on the other surface (z=h) of the plate the boundary conditions are prescribed unmixed. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 5, pp. 902–906, September–October, 2000.     

A class of integral transformations for the generalized equation of nonstationary heat conduction

Integral transformations for finding analytical solutions of the boundary-value problems of nonstationary heat conduction for the generalized equation of transfer in an infinite region bounded on the inside by a plane, cylindrical, or spherical surface have been constructed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 123–130, January–February, 2008.     

Temperature mechanisms of the interaction of dislocations with impurities in the processes of transfer of the energy of elastic vibrations

The influence of microplasticity caused by the motion of dislocation segments on the propagation of elastic vibrations in structural materials is considered. It is shown that the character of motion of a dislocation segment exerts its effect on the propagation velocity of an acoustic wave. This fact should be taken into account when nonstationary frequency-phase methods of measuring the physical parameters of a medium are used. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 193–199, July–August, 2007.