Slow motion of a granular layer on an inclined plane

The shape of the free surface of a layer of granular material moving on an inclined plane is studied on the basis of a model of a non-Newtonian fluid with a nonlinear relation between the stress tensor and the shear rate of the flow. For small but finite elevations of the free surface, the governing equations are reduced to a quasilinear Burgers equation. Results of a numerical solution are presented for the case of arbitrary elevations. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 2, pp. 117–120, March–April, 1998.     

Mass transfer with gas desorption from the surface of a liquid film in the presence of a cocurrent flow

Results of a thcoretical and experimental study of dynamics and mass transfer during desorption of a gas from a liquid film in the presence of a cocurrent air flow are presented. The calculation model is based on solving integral momentum and diffusion relations for the gaseous and liquid phascs. Both laminar and turbulent regimes of the film flow are analyzed. The experimental study of mass transfer was conducted for carbon dioxide desorption from a water film. Criterial relations for mass transfer in the gaseous and liquid phases are obtained. The experiments showed that the heat-transfer coefficients for the case under study are one order of magnitude grcater than those for the flow of a smooth film. Possible mechanisms of such an appreciable intensification of the liquid-film mass transfer in a cocurrent gas flow are discussed. Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 4, pp. 131–138, July–August, 2000.     

Changes of a porous structure in flow of a monodisperse medium

The motion of fluids with suspended particles in porous media is considered. A mathematical model for the interaction of a monodisperse suspension with a porous structure is proposed. Changes in the parameters of the medium and the flow are studied for equilibrium regimes. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 113–121, March–April, 2000.     

Numerical simulation of aerosol sampling from an air flow to an input tube

The processes of sampling (aspiration) to an input tube of an aspiration probe from an ambient air flow are studied numerically. The air flow is simulated on the basis of three-dimensional Navier-Stokes equations for an incompressible fluid. The method proposed allows calculation of the aspiration efficiency in the case of rather complicated shapes of the limiting trajectories of the particles. Dependences of the aspiration efficiency on the mean velocity of suction of air into the tube and the size of particles for a given free-stream velocity are obtained. Research Institute of Aerobiology, State Research Center of Virusology and Biotechnology “Vector,” Novosibirsk Region, Kol’tsovo 633159. Institute of Computing Technologies, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 5, pp. 113–122, September–October, 1999.     

The flow in a planar-radial vortex chamber. 1. An experimental study of the velocity field in transient and steady flows

Two methods for determining the flow velocity in a vortex chamber of planar-radial geometry under transient and steady-state conditions are proposed. Local flow velocities throughout the entire volume of the chamber are measured, and the flow is found to be rotational. The effect of accumulation of particles heavier than air in the butt-end boundary layer is revealed. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 6, pp. 112–121, November–December, 1999.     

Kinetics of charge-exchange interaction of dense flows

The nonlinear problem of charge exchange between an ion flow and neutral particles is considered. An exact solution of the equations of charge-exchange interaction in plane geometry is found. Parameters determining the effectiveness of interpenetration of dense flows and the structure of the layer of intense interaction are obtained. Institute of Laser Physics, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 11–19, March–April, 2000.     

Solution of the perturbation problem for a shear flow with nonmonotonic velocity profile

Novosibirsk State University, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 36, No. 5, pp. 7–15, September–October, 1995.     

Criterion of formation of a shock wave reflected from a cloud of particles

The problem of the formation of a “collective” shock wave reflected from a cloud of particles, which was previously observed in experiment, is considered. A criterion of formation of a reflected shock wave is obtained based on the numerical and analytical solutions of the problem. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 44–51, May–June, 1998.     

Coalescence of oil drops on the skeleton of a porous medium in filtering a water-oil mixture

Two mathematical models of filtration coalescence of oil drops when a water-oil mixture moves through a porous material are proposed. In the first model, coalescence is interpreted as the process of sorption, i.e., the accumulation of the oil phase on the pore surface up to a definite critical value above which the larger drops involved by a filtration flow stall. The second model assumes that the motion of the sorbed oil and the entire mixture obeys the generalized Darcy laws. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 118–124, November–December, 1998.     

Characteristic properties of the system of equations of a shear flow with nonmonotonic velocity profile

Institute of Hydrodynamics, Russian Academy of Sciences; Novosibirsk State University, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizka, Vol. 36, No. 3, pp. 53–59, May–June, 1995.     

Studying heat exchange of dispersion-drop gas-liquid flow in granular layer

Conclusions Experimental procedure has been developed for physical modeling of monopropellant decomposition in a catalytic packet upon limiting stage of the process, i.e., during evaporation of a liquid in drop conditions. Heat exchange of liquid drops in a catalyst layer heated to high temperatures has been analyzed. Experimental dependence of a volume heat transfer coefficient on grain diameter, liquid flow rate and catalyst material has been obtained. It has been shown that within parameter variations this coefficient is practically independent of the gas velocity and drop diameter. Evaporation mechanism of drops in a heated granular layer has been discussed and carried out. For a more comprehensive examination of the interaction mechanism between the drops and the catalyst layer, a further experimental investigation is necessary in a wider range of change of the basic parameters of the process and use of mathematical modeling in analyzing experimental data. Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 118–123, July–August, 1994.     

Two alternatives of magnetic cumulation

This paper deals with phenomena leading to a considerable increase in magnetic field and energy density during compression of a magnetic flux trapped by a conducting shell and joint deformation of a magnetic field and material. The main features and merits of these two alternative schemes of magnetic cumulation are discussed. A comparison is made between the classical and schock-wave schemes of magnetic compression in a material with a phase transition from a nonconducting to a conducting state. The possibility of magnetic-energy cumulation during stretching of magnetic field line by a transverse flow of a conducting material is considered. Lavrent’ev Institute of Hydrodynamics, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 5, pp. 32–47, September–October, 2000.     

Interaction of a shock wave with a cloud of particles of finite dimensions

Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 2, pp. 26–37, March–April, 1994.     

Kinetic equations for a finely dispersed rarefied gas suspension

Starting from the Liouville equation, the kinetic equations for a finely dispersed rarefied gas-particle medium are derived. The size of the suspension particles is assumed to be much less than the free path of the gas molecules, while their density is so small that interaction between the particles can be neglected. It is shown that in general the dynamics of this gas suspension can be described by a system of two kinetic equations, which differ radically from the Boltzmann equations. Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 165–171, March–April, 1994.     

Two-dimensional problem of a uniform flow of a two-layer fluid of finite depth past a circular cylinder

The linear steady problem of an irrotational uniform flow past a horizontal circular cylinder located in the upper or in the lower layer of a two-layer fluid is solved by the multipole-expansion method. The flow is perpendicular to the axis of the cylinder. The fluid is assumed to be inviscid and incompressible, and the flow in each layer is assumed to be potential. The upper layer can be bounded by a free surface or a solid lid, and the lower layer by a rigid horizontal bottom. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 91–101, November–December, 1998.     

Numerical study of flows of reacting composite mixtures

A distributed mathematical model is proposed to describe a flow of a mixture of gases, fine particles of a reacting metal, and droplets of a hydrocarbon fuel. The heterogeneous chemical reaction of low-temperature oxidation of the metal, the homogeneous oxidation reaction of the reacting vaporized liquid fuel, and the difference in phase velocities and temperatures are taken into account. It is shown that this model can be used to describe the problems of detonation in a mixture of a reacting gas and reacting solid particles, and the problems of ignition of a mixture of aluminum particles and tridecane droplets. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 2, pp. 128–136, March–April, 1999.     

Efficiency of a protective gas film with high injection ratios in a highly turbulent main flow

Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 48–52, January–February, 1994.     

Formation of a petal-shaped structure at the front of an axisymmetric liquid film induced by collision of a drop with a flat surface

A model for the formation of a petal-shaped structure is proposed that is based on Rayleigh-Taylor instability occurring at the stage of transition of supersonic flow to forced flow. At this stage, there is abrupt deceleration of the flow, reaching (10 ⁸–10¹⁰)g. A dispersion relation is derived that allows one to obtain the length of the wave whose amplitude increases with maximum rate. The number of petals formed is determined assuming that this quantity is constant in time. Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 6, pp. 91–96, November–December, 1999.     

Analysis of stability of a thin layer of granular material moving on an inclined plane

The stability of a layer of a granular medium on an inclined plane has been studied within the framework of the model of a non-Newtonian fluid with an index of 2, which ensures the experimentally found quadratic dependence of the shear stress on the shear rate. It is shown analytically and numerically that these flows are stable or unstable depending on the value of the generalized Reynolds number relative to the critical value equal to5 cot α. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 113–117, November–December, 1998.     

Gravity-flow structure in a miscible fluid

Steady-state density flows in a horizontal channel are studied based on a two-layer shallow water model, developed by the author, with allowance for the mixing between the layers. The structure of a gravity flow and the intensity of mixing in the flow head are shown to depend significantly on the channel depth. Conditions behind the flow front, which determine the basic characteristics of a gravity flow, are found. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 79–85, May–June, 1998.