Mathematical treatment of the discharge of a laminar hot gas in a stagnant colder atmosphere

We study the boundary-layer approximation of the classical mathematical model that describes the discharge of a laminar hot gas in a stagnant colder atmosphere of the same gas. We prove the existence and uniqueness of solutions to a nondegenerate problem (without zones of stagnation of gas temperature or velocity). The asymptotic behavior of these solutions is also studied __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 192–205, July–August, 2008.     

Linearized Burnett Equation for the Dynamic Pressure of a Relativistic Gas

The linearized Burnett equation for the dynamic pressure of a relativistic gas of hadrons is calculated from a relativistic kinetic theory. It is shown, as in a previous paper [1], that the coefficient of the term with a non-homogeneous temperature field, – the heating term – is bigger than the one with the divergence of the four-velocity, – the bulk viscosity term.     

Thermohydrodynamics of continuous-wave CO2 lasers with a closed cycle of the flow

The problem of pressure losses upon gas motion along a closed circuit containing channels in which heat is supplied to and removed from the gas is studied. The object where the pressure losses are studied is a CO₂ laser with a crossflow. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 1, pp. 3–13, January–February, 2000.     

Formation of a gas hydrate due to injection of a cold gas into a porous reservoir partly saturated by water

Specific features of formation of gas hydrates due to injection of a gas into a porous medium initially filled by a gas and water are considered. Self-similar solutions of an axisymmetric problem, which describe the distributions of the basic parameters in the reservoir, are constructed. The existence of solutions is demonstrated, which predict gas hydrate formation both on the frontal surface and in the volume zone. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 137–150, May–June, 2008.     

Investigation of high-speed combustible gas ignited by a hot gas jetproduced in the shock tube

The high-speed combustible gas ignited by a hot gas jet, which is induced by shock focusing, was experimentally investigated. By use of the separation mode of shock tube, the test section of a single shock tube is split into two parts, which provide the high-speed flow of combustible gas and pilot flame of hot gas jet, respectively. In the interface of two parts of test sections the flame of jet was formed and spread to the high-speed combustible gas. Two kinds of the ignitions, 3-D “line-flame ignition” and 2-D “plane-flame ignition”, were investigated. In the condition of 3-D “line-flame ignition” of combustion, thicker hot gas jet than pure air jet, was observed in schlieren photos. In the condition of 2-D “plane-flame ignition” of combustion, the delay time of ignition and the angle of flame front in schlieren photos were measured, from which the velocity of flame propagation in the high-speed combustible gas is estimated in the range of 30–90m/s and the delay time of ignition is estimated in the range of 0.12–0.29ms. PACS 47.40.Nm; 82.40.FpPart of this paper was presented at the 5th International Workshop on Shock/Vortex Interaction, Kaohsiung, October 27–31, 2003.     

Reflection of pressure waves of moderate intensity at a solid wall in a liquid with bubbles of a readily soluble gas

The present paper is concerned with an experimental study of the process of gas dissolution behind a shock wave in a liquid with bubbles of a readily soluble gas, the influence of gas dissolution on the wave evolution, and strengthening of the shock wave after reflection from a solid wall. Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 5, pp. 19–24, September–October, 1998.     

On the transient regime in nonstationary supersonic flow past a body

The transient regime in gas flow past a stepwise accelerated body is analyzed by the method of singular perturbations at small Froude numbers. A marked effect of the initial conditions on the shock layer gas flow is demonstrated. The problem of flow past a wedge is solved in quadratures. St.Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 111–121, January–February, 1997.     

Possibility of reaching higher contents of a gas in a liquid using shock waves

The effect of shock waves on gas absorption by liquid in bubbly media with different degrees of gas solubility is studied. It is shown that a shock wave acting on a gas-liquid medium can significantly enhance the mass transfer between the gas and the liquid. Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 64–70, March–April, 2000.     

Numerical study of the interaction of a supersonic gaseous jet with a planar target

Various regimes of interaction of an axisymmetric supersonic underexpanded jet of a gas with both a finite and an infinite planar target are studied numcrically. The model of an idcal perfect gas and one variant of Godunov's highly accurate scheme are used. The calculated and experimental frequency spectra of pressure oscillations in the center of the target are compared: their good agreement is obscrved. Institute of Numerical Simulation. Siberian Division, Russian Academy of Sciences. 660036 Krasuoyarsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 4, pp. 106–111, July–August, 2000.     

Resonant oscillations of a gas in an open-ended tube in a weak turbulence regime

An analytical theory of resonant oscillations of a gas in an open-ended tube is developed. The gas flow in the tube is assumed to be turbulent. A model of gas flow near the open end of the tube is constructed. This model allows a boundary condition that is free of empirical parameters to be obtained. Theoretical results are in reasonable agreement with experimental data obtained by other authors. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 92–99, May–June, 1998.     

Description of the anomalous Rayleigh-Taylor instability on the basis of the model of dynamics of a three-velocity three-temperature mixture

A problem of evolution of the Rayleigh-Taylor instability on a sinusoidally perturbed interface in the field of artificial gravity is studied on the basis of the model of a three-velocity three-temperature mixture of gases. If the upper part of the mixture consists of the light and heavy gases (the heavy gas is heavier than the pure gas at the bottom, but the mixture as a whole is lighter than the pure gas), it is demonstrated that the growth of perturbations with formation of mixture jets penetrating into the pure gas is observed in a certain range of concentrations of the heavy gas. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 1, pp. 58–67, January–february, 2009.     

Unsteady filtration of a gas

The unsteady filtering flow of a gas described by the equations of motion proposed by Khristianovich in [1] is investigated. It is shown that for the gas flow in the pores a critical regime can develop when the reduced velocity (an analog of the Mach number in gas dynamics) is less than unity. The reduced velocity is the ratio of the flow velocity to the velocity of propagation of small filtering perturbations at a given point of the flow. St Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 201–203, January–February, 1994.     

Assessing the consequences of gas cloud transport over a stand of forest

A mathematical continuum model of a stand of forest for assessing the consequences of the movement of a gas cloud, formed as a result of an accident, industrial gas emission, or production testing, is presented. The Navier-Stokes, continuity and diffusion equations are used to investigate the accumulation of harmful impurities by the stand and their subsequent removal. The two-dimensional problem is solved in the natural variables (velocity and pressure) using the Belotserkovskii procedure and the geometric splitting method. Perm. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 79–87, July–August, 2000.     

Gas dynamics of a selectively excited gas

In order to describe the motion of a selectively excited gas, model kinetic equations are proposed in the present study, and they are used to construct the equations of gas dynamics. There is consideration of the one-dimensional problem of heat transmission between plates across a selectively excited gas. Discontinuities are found in the temperature on the boundaries of the phases. It is shown that a selectively excited gas may be used to transmit heat from a cold body to a hot one. Moscow. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 151–158, September–October, 1988.     

Effect of the accommodation coefficient on transfer processes in a supersonic rarefied gas flow around a transversely aligned cylinder

A supersonic flow around a cylinder is studied by the direct statistical Monte Carlo method in a wide range of rarefaction: from regimes close to continuum to free-molecular flow. The effect of the accommodation coefficient on the flow near the cylinder and on heat transfer between the gas and the cylinder is examined. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 64–72, May–June, 2008.     

An asymptotically self-similar solution of the problem of three-dimensional gas flow through a porous medium

An exact solution of the Cauchy problem is constructed for the equation describing the three-dimensional molecular diffusion of a gas. The result obtained is a natural generalization of the solution of the analogous Boussinesq problem. Dnepropetrovsk. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 178–180, September–October, 1988.     

Direct simulation Monte Carlo study of the formation and growth of clusters in the case of vapor expansion from a suddenly switched spherical source

The processes of formation of silicon clusters in the case of vapor expansion from a suddenly switched spherical source into an ambient inert gas are considered. Vapor expansion and condensation are described by the direct simulation Monte Carlo method. A model of clusterization is proposed, which describes reactions leading to the growth and decomposition of clusters and corresponding energytransfer processes. The main features of cluster formation in the case of vapor expansion into a gas are considered. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 1, pp. 101–109, January–February, 2009.     

Gas injection from the surface of a triangular plate in a hypersonic flow

The flow formed as a result of gas injection through the permeable surface of a triangular plate is investigated in the regime of strong viscous-inviscid interaction between the hypersonic flow and the laminar boundary layer. The features of the flow past strongly cooled surfaces with the formation of supercritical and subcritical flow regions in the boundary layer are studied. The injected gas distribution ensuring the existence of self-similar solutions in the supercritical flow regions is obtained. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 125–133, January–February, 2000. The study was carried out with the support of the Russian Foundation for Basic Research (project No. 96-01-01391).     

Motion of a gas inclusion in a capillary under the action of vibration

The motion of gas inclusions in a liquid-filled duct under the action of vibration for comparable cross-sectional dimensions of the inclusion and the duct is studied. Two limiting cases of inclusion motion differing with respect to the drag mechanism are considered. For low velocities, it is assumed that the drag is mainly determined by the capillary forces and the friction in the liquid film separating the gas inclusion from the duct wall. As the inclusion velocity increases, the main contribution to the drag is made by such mechanisms as flow separation, the formation of a low-pressure region in the wake, etc. It is demonstrated that due to the vibration a gas inclusion traveling in a capillary under the action of steady forces is halted at certain points of the capillary. The capillary behaves like a filter, impermeable for inclusions smaller than a certain threshold size. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 85–92, May–June, 1998. The work received financial support from the Russian Foundation for Basic Research (project No.96-01-01813).     

Determination of the catalytic activity of materials by solving the equations of a nonequilibrium multicomponent boundary layer on a flat plate

A method is presented for determining the dependence of the probability of heterogeneous recombination γw from results of measurements of the heat flux Q_w to the surface of a catalytic sensor exposed to a pulsed supersonic flow of gas dissociated by an incident shock wave propagating in a shock tube. It is shown that the accuracy of the determination of γw depends not only on the accuracy of the measurements in the experiment, but also on the results of mathematical modeling of the flow of the dissociated gas over the surface of the body. Results from an analysis of an experiment are presented. Institute of Applied Mathematics and Mechanics at Tomsk University, Tomsk 634050. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 4, pp. 110–117, July–August, 1998.