Specific features of electrification of weakly conducting media flowing through a plane channel with walls of different electrochemical properties

A flow of a multicomponent weakly conducting medium in a plane channel is studied. The medium consists of a carrier dielectric liquid and a small admixture of ions. The channel walls have different electrochemical properties. It is shown that, in the case of a weak foreign electrolyte, the volume and surface electrochemical processes are nonequilibrium along the entire length of the channel. It is also shown that in the saturation state there exists a finite negative charge flow through one of the walls and a positive charge flow of the same magnitude through the other wall.     

Investigation of the mechanisms of the onset of instability in weakly conduction media in electric fields

The initial stable state (of rest or laminar flow) of a weakly-conducting viscous multicomponent fluid in a plane channel, whose walls are electrodes with electrochemical properties varied in the process of investigation, are considered. The conventional electrohydrodynamic models of a medium with one or two charged particle components, whose concentrations are low compared with that of the neutral particles of the carrying fluid, are used. The time-dependent two-dimensional problem of the formation of the medium structure in the inter-electrode space after the voltage from the electrodes has been turned on is numerically solved. The obtained distributions of the Coulomb forces acting on the medium make it possible to develop several possible scenarios of the disturbance development, similar with those known in fluid dynamics. The realization of any of these scenarios considerably depends on the conditions at the electrode surfaces.     

Spherical blast waves in multicomponent media

The solution of the problem of propagation of a wave in soils is presented for the case when the wave is produced by the detonation of a spherical charge of some explosive material (EM). The solution is obtained on a computer by the method of characteristics. The soils are regarded as multicomponent media consisting of solid particles, water, and air in conformity with the model proposed in [1, 2]. The dependence of the pressure, velocity of the particles, and the density in the wave front on the distance is determined; the variation of these parameters with time at fixed points of the medium is also determined. The results are compared with the results of tests [1, 2]. Their close agreement for different contents of the components indicates the applicability of the multicomponent model to soils. The limits of applicability of the model are determined. The propagation of a plane wave under the same conditions was investigated in [3].     

Theory of plastic deformation for multicomponent porous media

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 115–120, September–October, 1991.     

Forces acting on a weakly conductive dielectric in an electric field

The nature of the forces acting on a weakly conductive liquid dielectric in an electric field will be considered. In the general case there act upon the liquid dielectric a Coulomb force related to space charge and a polarization force [1]. In many studies the motion of a conductive liquid dielectric has been explained by the presence of the polarization force, with the Coulomb force being ignored. In the present study it will be demonstrated that the force related to space charge may be larger than or of the same order as the forces connected with polarization of the medium and, generally speaking, must be considered in describing the equations of motion in concrete cases.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 155–157, January–February, 1977.     

Momentum and energy exchange in nonequilibrium multicomponent media

In multicomponent media, the equilibrium states are defined by thermodynamic equilibrium conditions in the form of the equalities between the pressures and temperatures of the components, the maximum entropy principle (or the free-energy minimum) for the mixture, and the equality of the velocities of the components. The conservation laws for the components allow for their interaction with each other in the form of forces and energy fluxes containing the differences of the velocities, pressures, and temperatures of the components. The form of momentum and energy exchange between each component and the continuum expressing the collective properties of the ensemble of components, is also considered. It is shown that these momentum and energy fluxes are different from zero only for the states of multicomponent media with velocity nonequilibrium.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 7–15, January–February, 2005.     

Numerical simulation of flow of multicomponent mixtures in porous media

A study is made of the isothermal flow of multicomponent mixtures in a porous medium, accompanied by phase transitions, interphase mass exchange, and change in the physicochemical properties of the phases [1–3], It is assumed that at each point of the flow region, phase equilibrium is established instantaneously and the flow velocities of the separate phases conform to Darcy's law. Approximate solutions of problems of displacing oil by high-pressure gas were obtained in [1]. By generalizing the theory developed in [4], a study is made in [5] of the structure of the exact solutions of the problems of the flow of three-component systems which describe the displacement of oil by different reactants (gases, solvents, micellar solutions). The numerical solutions of the problems of multicomponent system flow are considered in [2, 3, 6, 7]. This paper presents a numerical method which is distinguished from the well-known ones [2, 3, 6, 7] by the following characteristics. The flow equations are approximated by a completely conservative finite-difference scheme of the implicit pressure-explicit saturation type, the calculation being carried out using Newton's method of iteraction with spect to both the pressure and the composition of the mixture. The minimum derivative principle [8] is used in the approximation of the divergence terms of the equations. The phase equilibrium is calculated using the equation of state.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 101–110, July–August, 1985.     

Transition to steady-state solutions of the equations of multicomponent flow through porous media

The question of the dynamics of the approach to steady-state solutions is examined in relation to the system of equations of equilibrium multicomponent two-phase flow through porous media [1, 2]. The equations are analyzed in the linear approximation for the case of small fluctuations. An expression is obtained for the characteristic transition time. Numerical modeling is carried out for substantial deviations from the steady-state solution. The problem of the plane linear displacement of a ten-component gas-condensate mixture by an enriched gas with subsequent transition to the extraction regime is solved. It is shown that the change in phase compositions and pressure proceeds with characteristic times of the order of the time required to create a spatially nonuniform distribution of the mixture properties during injection. However, the change in the saturations and overall composition takes place in times approximately 200 times greater than the injection time. The question of the existence of discontinuous steady-state solutions of the system of equations investigated is considered, and in the case of a binary mixture it is shown that such solutions cannot be realized.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 130–135, November–December, 1988.The author is grateful to V. N. Nikolaevskii for discussing his work.     

Consideration of variable viscosity in the dynamics of soils and porous multicomponent media

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 119–126, May–June, 1990.     

Modeling viscosity and diffusion of plasma for pure elements and multicomponent mixtures from weakly to strongly coupled regimes

An analytic model is presented that predicts viscosity and diffusion of plasma for pure elements and multicomponent mixtures, from the high-temperature low-density weakly coupled regime to the low-temperature high-density strongly coupled regime. It relies on a pseudo-ion in jellium modeling that incorporates the effect of electron screening on the ion–ion interaction in the pseudo-ionization. Mixtures are treated using approximate kinetic expressions and mixing laws applied to the excess viscosity and self-diffusion of pure elements. Comparisons are made with classical and quantum molecular dynamics results to assess its accuracy. The mean deviations are in the range 20–40% with almost no predictions further than a factor of 2 over many decades of variation. Applications of this model in the inertial confinement fusion context could help in predicting the appearance and the growth of hydrodynamic instabilities.     

Steady and unsteady regimes of flow of a multicomponent sorbable mixture through porous media

The paper contains an analysis, confirmed by computer-calculated numerical examples, of the one-dimensional nonstationary system of equations describing the concentration distributions of sorbable gases or liquids in a porous sorbent and in a flow through it. Solutions in the form of propagating waves are investigated in detail. The wave regimes for model sorption isotherms are classified. A representation for quasitraveling and quasispreading waves is introduced.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 114–123, November–December, 1982.