Wavelet-Based Analysis of Parametric Vibrations of Flexible Plates

Wavelet-based methods are reviewed, and their advantages in comparison to standard approaches are outlined. Then, a wavelet analysis is performed to investigate parametric vibrations of flexible plates under a sinusoidal load. In particular, a scenario leading from regular motion to chaos is analyzed     

Influence of Molecular Characteristics of a Substance on Detonation Phenomena

In the present study, the molecular-dynamics method has been used to examine the influence of the thermal effect of the chemical reaction on processes in a detonating molecular crystal (propagation velocity and structure of the detonation wave, delay time of the chemical reaction, and energy macrocharacteristics of the crystal in the disturbed region). Molecular-dynamics data are compared with predictions of the continuum theory of detonation; in particular, fulfillment of the Chapman–Jouguet condition is verified.     

Investigation of the rarefied gas flow around a circular cylinder in stationary and oscillatory regimes

Numerically, on the basis of the Krook kinetic equation, the rarefied gas flow around a circular cylinder is investigated in stationary and oscillatory regimes. The flows around a rotating cylinder and a cylinder with a nonuniformly heated surface are considered. The Knudsen numbers at which the lift force acting on the rotating cylinder changes sign are calculated. It is shown that at low Knudsen numbers a lift force acts on the nonuniformly heated cylinder.     

Laminar boundary layer in a flow past an aerofoil with a circular cavity

The paper describes a numerical study of a method of preventing the separation of a laminar boundary layer from the forward section of a symmetric aerofoil, the flow past which does not separate at zero angle of incidence. In order to increase the maximum angle of incidence at which the flow has still not separated, a circular cavity (vortex cell) located almost completely inside the aerofoil is introduced on the segment vulnerable to separation. The asymptotics of the corresponding flow at high Reynolds number are described using the Prandtl-Batchelor model. Krasnodar. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 52–57, March–April, 1998. The work was financially supported by the International Science Foundation (grants M4K000 and M4K300) and by the Russian Foundation for Fundamental Research (project No. 96-01-01290).     

Application of rainbow schlieren deflectometry for concentration measurements in an axisymmetric helium jet

 The rainbow schlieren deflectometry technique was used to measure oxygen concentrations in a laminar, isothermal helium jet discharged vertically into ambient air. The concentration distributions were inferred from the color schlieren image by taking into consideration the sampling interval and noise in measurements, especially near the jet center. Excellent quantitative agreement was reached between measurements from schlieren and a continuous sampling probe. This work demonstrates the capability of the schlieren technique for providing accurate, spatially-resolved, nonintrusive, full-field of view measurements of species concentration in an isothermal binary system. Because the basic quantity measured is the refractive index, the present schlieren technique can be extended for quantitative measurements of other scalar flow properties related to the refractive index. Received: 21 April 1997 / Accepted: 14 November 1997     

The Stress–Strain State of Geometrically and Physically Nonlinear Plates with One-Sided Corrosive Wear

A technique is proposed to investigate one-sided corrosive wear. The problem is solved with regard for geometric and physical nonlinearity. Two, Dolinskii's and Gutman's corrosion models are considered. The quasistatic problem is solved by the method of variational iterations, which reduce ordinary differential equations to a system of nonlinear equations with approximation o(h ²) to be solved by Newton's method. At each step, to allow for physical nonlinearity, the method of variable elastic parameters is used. Also a technique is developed to consider various boundary conditions and ⁱ(e ⁱ) diagrams. Specific numerical results are presented.     

Excitation of Van Kampen-case waves

The response of a fluid with a shear flow having a slightly curved profile to an external vertical impact force, harmonic with respect to the horizontal coordinate and concentrated in a narrow layer, is calculated. The cases of an ideal and a viscous fluid are considered.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 115–119, January–February, 1987.The author wishes to thank G. I. Barenblatt, M. A. Mironov, and S. A. Rybak for useful discussions.     

Boundary kinetic effects in the problem of slow flow over an evaporating heat-conducting spherical particle

It is shown that for sufficiently large values of the thermal conductivity of the condensed phase' as compared with the thermal conductivity of the vapor (/' Kn) the effects associated with the presence of a Knudsen layer on the evaporating surface must be taken into account in order to obtain a solution of the problem of a spherical particle in a slow (Re, 1) continuum (Knudsen number Kn 1) flow of its own vapor. The drag is calculated for various types of boundary conditions on the particle surface.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 134–139, March–April, 1987.In conclusion the authors wish to thank V. S. Galkin and M. N. Kogan for useful discussions.     

Stretching of squeezed liquid under the action of its own weight

The stretching of a liquid sample, squeezed out in the vertical direction from an aperture of an arbitrary form, is investigated. The problem of controlling the dimensions of the aperture or the rate of squeezing for obtaining samples of a given configuration is discussed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 10–14, September–October, 1975.     

Limiting energy characteristics of pulsed tea co2 lasers

The article presents the results of experimental studies on the determination of the characteristics of the process of absorption of large specific electrical energy densities in a wide range of pressures (0.1–0.5 atm CO₂?2N₂?0.5H₂). The presence of limitations (E₀/p ≥45 V/cm · torr, Q/p=? 1 J/cm³ · atm) which are responsible for the region of existence of a diffusional discharge was established, which made it possible to determine the relationship between the limiting electrical energy density which can be absorbed in the discharge, the initial parameters of the system, and the amount of radiated energy.