Development of ship waves in a nonhomogeneous liquid

The article discusses the three-dimensional problem of unsteady-state waves arising on a free surface and at the interface between two liquids of different densities, with motion of the source. Analogous problems for steady-state waves in a two-layer liquid have been investigated in [1–6], and for unsteady-state waves in a homogeneous liquid in [7, 8].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 137–146, July–August, 1970.     

Theory of the combustion of small drops of metal

The article discusses the combustion of small drops of metal. It is postulated that the formation of an oxide in the liquid phase starts with the origin of a condensed phase and continues as the result of a reaction between the vapors of the drop and the oxidizer at the surface of the forming particles of the condensed phase. It is shown that the process of the formation of particles of condensed oxide in the gas, for very small drops, has an essentially unsteady-state character. Under these circumstances, a considerable fraction of the vaporization products of a drop does not succeed in condensing after the complete gasification of the drop and remains in the gaseous state.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 47–53, March–April, 1976.     

Accelerated supersonic motion of a plate with a finite angle of attack

The article considers the supersonic unsteady-state motion of a plate with a finite (but infinitely small) angle of attack with an associated shock wave in an ideal gas. The laws governing the change of the velocity and the angle of inclination of the plate are assumed to be arbitrary, and the Strouhal numbers are assumed to be small. Under the latter assumption and with Mach numbers in the perturbed region not too close to unity, the prehistory of the motion is sufficiently well described by the instantaneous values of the parameters of the unsteady state and their derivatives. This fact permits a considerable simplification of the equations describing the perturbed unsteady-state motion, and an analytical solution.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 70–75, July–August, 1970.     

Unsteady-state flow of a gas in a channel,resulting from the motion of a piston,with magnetohydrodynamic offtake of energy and luminescence of the gas

The present paper discusses the one-dimensional unsteady-state flow of a gas resulting from the motion of a piston in the presence of weak perturbing factors, with which the investigation of the perturbed (with respect to the usual self-similar conditions) motion reduces to the solution of ordinary differential equations, is indicated. The distributions of the parameters of the gas between the piston and the shock wave are found. The conditions under which there is acceleration or slowing down of the shock front are clarified. As an example, this paper considers the unsteady-state motion of a conducting gas in a channel with solid electrodes under conditions where electrical energy is generated, and the flow of a gas taking radiation into account, under the assumption of optical transparency of the medium. The theory developed is used to solve the problem of the motion of a thin wedge with a high supersonic velocity in an external axial magnetic field, taking account of the luminescence of the layer of heated gas between the wedge and the shock wave.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 17–25, September–October, 1970.     

Experimental investigation of the characteristics of unsteady-state breakaway zones arising in a supersonic flow at a needle with a screen

An experimental investigation of unsteady-state flow in a breakaway zone arising at a needle installed ahead of a conical screen and ahead of a screen located in a cylindrical resonance cavity was made.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 98–104, July–August, 1977.     

Unsteady-state periodic jet structure created by the pulsed motion of a piston jet generator

The results of an experimental and theoretical investigation of the process of formation of an unsteady-state water jet by the pulsed motion of the piston of a piston jet generator are given. An approximate mathematical model of the generator dynamics which can explain the mechanism of formation of the experimentally obtained periodic transverse thickening structure is considered.Nikolaev. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 172–178, July–August, 1996.     

Formation of a region of interaction and of a wake with the instantaneous start of a plate in an incompressible liquid

The flow arising in an incompressible liquid if, at the initial moment of time, a plate of finite length starts to move with a constant velocity in its plane, is discussed. For the case of an infinite plate, there is a simple exact solution of the Navier—Stokes equations, obtained by Rayleigh. The case of the motion of a semiinfinite plate has also been discussed by a number of authors. Approximate solutions have been obtained in a number of statements; for the complete unsteadystate equations of the boundary layer the statement was investigated by Stewartson (for example, [1–3]); a numerical solution of the problem by an unsteady-state method is given in [4]. The main stress in the present work is laid on investigation of the region of the interaction between a nonviscous flow and the boundary layer near the end of a plate. In passing, a solution of the problem is obtained for a wake, and a new numerical solution is also given for the boundary layer at the plate.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 3–8, March–April, 1977.     

Drop evaporation in a turbulent gas jet

Evaporation of a semidispersive drop system in a turbulent gas jet is considered. A method for calculating drop evaporation in a turbulent gas jet is proposed based on a simplified solution of the scattering problem for an evaporating admixture. Evaporation of water as it is atomized in a turbulent air jet is experimentally studied. Approximate agreement is obtained between the results of the calculations and experiments.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 73–79, January–February 1976.     

Investigation of the properties of a shock wave arising in a supersonic flow of plasma,passing through a transverse magnetic field

In a flow of plasma, set up by an ionizing shock wave and moving through a transverse magnetic field, under definite conditions there arises a gasdynamic shock wave. The appearance of such shock waves has been observed in experimental [1–4] and theoretical [5–7] work, where an investigation was made of the interaction between a plasma and electrical and magnetic fields. The aim of the present work was a determination of the effect of the intensity of the interaction between the plasma and the magnetic field on the velocity of the motion of this shock wave. The investigation was carried out in a magnetohydrogasdynamic unit, described in [8]. The process was recorded by the Töpler method (IAB-451 instrument) through a slit along the axis of the channel, on a film moving in a direction perpendicular to the slit. The calculation of the flow is based on the one-dimensional unsteady-state equations of magnetic gasdynamics. Using a model of the process described in [9], calculations were made for conditions close to those realized experimentally. In addition, a simplified calculation is made of the velocity of the motion of the above shock wave, under the assumption that its front moves at a constant velocity ahead of the region of interaction, while in the region of interaction itself the flow is steady-state.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 86–91, January–February, 1975.     

Unsteady-state filtration from screened water reservoirs and from the storage elements of industrial drainage systems

This paper considers the axisymmetric problem of unsteady-state filtration from a water reservoir or from the storage element of industrial drainage systems, which are round in a plan view.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 165–170, November–December, 1971.     

Mass transfer between particles and a flow in the presence of a volume chemical reaction

The exterior problem of the mass transfer between a spherical drop and a linear shear flow in the presence of a first-order volume reaction is solved in the diffusion boundary layer approximation. A simple approximate expression for calculating the average Sherwood number for a drop or solid particle of arbitrary shape is proposed. At large Péclet numbers this expression is applicable to any type of flow over the entire range of variation of the reaction rate constant. The problem of diffusion to a spherical drop in a translational Stokesian flow in the presence of a first-order volume reaction was investigated in [1].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 109–113, November–December, 1987.     

Calculation of the unsteady-state aerodynamic characteristics of three-dimensional bearing systems

At the present times effective numerical methods have been developed for solving both steady-state and unsteady-state linear problems on the determination of the aerodynamic characteristics of wings of complex form, in a plan view [1–3]. The transition to three-dimensional systems requires the development of new methods. There are a number of known investigations in this direction, for simple three-dimensional configurations [4–7]. The present article proposes a method for solving supersonic problems of the determination of the steady-state and unsteady-state three-dimensional bearing systems. It is a development of known methods for calculating wings of complex form in a plan view. The most effective route is one based on a solution of the problem for stepwise dependences on the time. After this, the transition to any other laws is effected using a packet integral.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 173–176, January–February, 1976.     

Propagation of a flush wave in a prismatic channel

By a water flush there is generally understood an unsteady-state flow of water, arising in millraces, with the breaching (rupture) of a dam. The special characteristics of a flush wave are also possessed by a flow in a lower millrace at some distance from the dam, with the overflow of water arising in the reservoir over the crest of the dam. Usually, the necessary information on the parameters of a flush wave with its motion in natural channels is obtained by numerical solution, in a digital computer, of the equations of not fully established one-dimensional flow [1–3]. These calculations are very labor-consuming and require rather detailed information on the channel. Therefore, it is of practical importance to clarify the overall laws governing the propagation of flush waves in schematized, in particular, in prismatic channels. In some cases, on the basis of such laws, it is possible to make a preliminary diagnosis of the expected scales of the phenomenon.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 39–44, January–February, 1975.     

Spherical flow of a diatomic gas from an evaporating drop

The spherical expansion of gas from an evaporating drop is investigated on the basis of the numerical solution to a model kinetic equation for a gas with rotational degrees of freedom. Examples considered are the stationary evaporation of a drop with given temperature into the vacuum and evaporation of a drop into a gas-filled space under the condition of an energy balance on the drop surface.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 184–187, July–August, 1980.     

Gravity-induced spreading of a drop of a viscous fluid over a surface

The unsteady-state nonlinear problem of spreading of a drop of a viscous fluid on the horizontal surface of a solid under the action of gravity and capillary forces is considered for small Reynolds numbers. The method of asymptotic matching is applied to solve the axisymmetrical problem of spreading when the gravity exerts a significant effect on the dynamics of the drop. The flow structure in the drop is determined at large times in the neighborhood of a self-similar solution. The ranges of applicability of the quasiequilibrium model of drop spreading with a dynamic edge angle and a self-similar solution are found. It is shown that the transition from one flow model to another occurs at very large Bond numbers. Institute of Mechanics of Multiphase Systems, Siberian Division, Russian Academy of Sciences, Tyumen’ 625000. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 3, pp. 59–67, May–June, 1999.     

Unsteady-state filtration of a liquid in a fractured-porous stratum to a well with a hemispherical end-face

A study is made of the motion of a liquid toward a well with a hemispherical end-face with unsteady-state spherical-radial filtration in a fractured-porous stratum consisting of hemispherical regions with different values of the permeability of the system of cracks, superposed one on another. A Laplace transform is used to find exact solutions to the problem of the lowering of the stratum pressure as a function of time and distance as well as of the output of a well working with a constant end-face pressure. The article discusses partial cases corresponding to the exploitation of closed and bounded open fractured-porous strata by a central well with a hemispherical end-face. On the basis of numerical calculations, the effect of the parameters of fractured-porous strata on the change in the indices of the process of their exploitation is established. It is established that, with the exploitation of fractured-porous strata, the process of the lowering of the end-face pressure of the well and its output become stabilized with sufficiently large values of the time.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 115–123, November–December, 1973.     

Chemoconcentration capillary effect associated with the motion of a drop in a liquid

The effect of a surface chemical reaction involving a weak soluble surface active substance on the motion of a drop in a liquid is investigated. It is shown that as a result of the Marangoni effect the non-uniformity in the distribution of the substance along the surface associated with the proper motion of the drop and the chemical reaction has an important influence on the nature of the motion of the drop and on the force exerted by the surrounding Liquid. Under certain conditions this Leads to the development of a thrust proportional to the velocity of the drop (chemoconcentration capillary effect). The condition of occurrence of the thrust is obtained, together with its dependence on various physical parameters.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 147–154, January–February, 1988.     

Development of the region of a turbulized liquid in a stratified medium

The article discusses the plane unsteady-state problem of the development of a region of turbulent pulsations in an incompressible stratified liquid. At the initial moment of time, the energy of the turbulence is given inside a region of finite dimensions. A semiempirical system of equations describing this process is proposed. The article gives the data from numerical calculations, illustrating the original expansion of the region as a result of turbulent diffusion, its subsequent compression along a vertical (collapse) under the action of the forces of buoyancy, and the internal waves generated by the collapse.The work was reported at the International Symposium on Stratified Flows (Novosibirsk, August 29–31, 1972).Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 45–52, May–June, 1974.     

Motion of a drop with allowance for thermocapillary forces

A study is made of the motion of a drop in a viscous medium of nonuniform temperature when the dependence of the surface tension on the temperature at the interface of the two media gives rise to additional tangential stresses leading to thermocapillary convection in fluids. The motions of a spherical drop and a deformed drop (when the surface of the drop is determined in the process of finding the solution) are considered. The shape of the drop surface is calculated for different values of the parameters of the problem. Dependences are obtained for the Reynolds number of the thermocapillary drift of drops in the absence of body forces.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 80–86, July–August, 1982.     

Supersonic unsteady-state flow around bodies of variable form

This paper discusses supersonic flow around a spherical blunt body, whose surface is deformed according to a known law over a certain period of time. An investigation is made of unsteady-state flows during the change in the form of the body as a function of the deflection and the rate of change in the form of the body. The calculations were made for Mach number M =2, 10. The solution is obtained by the grid-characteristic method [1].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 187–191, November–December, 1978.