The temperature coefficients of delay of surface acoustic waves in LGS and LGN crystals in a wide temperature range

Numerical analysis of the first-and second-order temperature coefficients of the delay of surface acoustic waves (SAWs) in LGS and LGN crystals was carried out. The calculations were performed along thermostable directions in a wide temperature range. The effect of an aluminium layer having a finite thickness on the SAW temperature characteristics is shown.     

On the convergence for kinetic variational inequality to quasi-static variational inequality with application to elastic-plastic systems with hardening

In this note, a priori estimates for the kinetic problem are obtained that imply, that the kinetic solutions converge to the quasi-static ones, when the size of initial perturbations and the rate of application of the forces tend to 0. An application to three-dimensional elastic-plastic systems with hardening is given. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Generation of the tollmien–schlichting wave in a supersonic boundary layer by two sinusoidal acoustic waves

The problem is solved using parabolized equations of stability for threedimensional perturbations of a compressible boundary layer on a flat plate. Nonlinearity is taken into account by quadratic terms that are most significant in estimates of the viscous critical layer of the stability theory. These terms are determined by the total field of two acoustic perturbations, and the equations become linear and inhomogeneous. The calculations are performed for one acoustic wave being stationary in the reference system fitted to the plate for Mach numbers M=2 and 5. Solutions are presented, which are identified very accurately with Tollmien–Schlichting waves at a rather large distance from the plate edge.     

Advance of the interface of liquids with pressure filtration

The article is a continuation of the investigations of a number of authors [1–3] on the advance of the interface between different liquids: it gives a solution of the problem in the case of one-dimensional filtration of liquids with different viscosities in distorted layers of variable permeability; it indicates a method for determining the interface between multicolored liquids, and the method is generalized for the case of a series of two-dimensional flows, connected by a conformai transformation. The article discusses problems that reduce to formation of the functions determining the flow, and to calculation of the integrals.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 185–191, September–October, 1971.     

Mechanism of formation of vortex rings

It is demonstrated experimentally that a vortex ring is created by the slowing down of the central part of a stream and that during formation of this ring the amount of the mass of liquid participating in its formation can change. The possibility is also established of obtaining liquid vortex blobs in the form of hemispheres or spheroids.Deceased.Translated from Izvestiya Akademii Nauk SSSR. Mekhanika Zhidkosti i Gaza, No. 2, pp. 19–26, March–April, 1973.In conclusion, the author thanks G. A. Lyubimov and A. T. Onufriev for useful discussions of the data from the investigations, and O. M. Belotserkovskii for interest in the work.     

Low-frequency oscillations of the plasma of a circular discharge in crossed electric and magnetic fields

Low-frequency oscillations in a circular discharge plasma are studied experimentally. Values of the magnetic field corresponding to the generation and collapse of ionization oscillations are determined. An analysis of plasma stability in the absence of ionization equilibrium is conducted. Agreement is noted between the theoretical and experimental results.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 171–173, May–June, 1972.     

Investigation of Nonuniformity of the Velocity Distribution in the Shear Layer of an Underexpanded Jet by Electric Discharge Tracing of the Flow

Streamwise and radial components of velocity in the shear layer of an underexpanded jet are measured by the method of spark tracing. The nonuniform distribution of gas-dynamic parameters of the flow in this region is caused by streamwise Görtler-type vortex structures.     

Curvilinear motion of an ellipsoidal bubble

The Lagrange equations are used to investigate the curvilinear motion of an ellipsoidal bubble. At a small inclination of the minor axis of the ellipsoid to the vertical, the ellipsoid begins to oscillate about the equilibrium position and its trajectory begins to swing. Analytic expressions are presented for the oscillation frequency and for the ratio of the swing amplitude to the amplitude of the oscillations of the ellipsoid. It is assumed that the bubble has the form of an axially symmetrical ellipsoid [1].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 90–93, May–June, 1971.     

On the shape of bodies ablating in a supersonic gas stream

When objects move at a high velocity in a dense medium, their front surfaces undergo intense heating. There can then be a strong interaction between the oncoming flow and the surface of the body in which the body is not merely subject to the thermal and force effect of the stream but also significantly changes the flow field itself due to the intense blowing of ablation products from its surface and the change in the geometry of the front surface. Experimental and numerical investigations into the various regimes of strong interaction have established how stable shapes are adopted by bodies ablating in a supersonic gas stream.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 18–21, January–February, 1981.     

Dynamics of an elliptic vortex

The two-dimensional flow of an ideal incompressible fluid is considered. Within an ellipse, the flow has a constant vorticity, while outside the ellipse there is an irrotational flow with circulation. Such motion can be described by Lagrange equations for a dynamical system with an infinite number of degrees of freedom. For a system with four degrees of freedom a new steady solution is obtained and its stability investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 55–60, July–August, 1983.We thank L. I. Sedov for his interest in the work.