Showing papers in "Journal of Applied Mechanics and Technical Physics in 1985"

Interaction of air shock waves with porous compressible materials

Abstract: J. J. Keller, "Nonlinear acoustic resonances in shock tubes with varying cross-sectional area," Z. Angew. Math. Phys., 28, No. i, 107 (1977). L. P. Gor'kov, "Nonlinear acoustic oscillations of a gas column in a closed tube," Inzh. Zh., 3, No. 2 (1963). W. Chester, "Resonant oscillations in closed tubes," J. Fluid Mech., 18, Part ii (1964). A. N. Kraiko and A. L. Ni, "Nonlinear acoustics approximation in problems of gas oscillations in tubes," Prikl. Mat. Mekh., 44, No. 1 (1980). A. L. Ni, "Nonlinear resonant oscillations of a gas in a tube under the action of a periodically varying pressure," Prikl. Mat. Mekh., 47, No. 4 (1983). Sh. U. Galiev, N. A. Ii'gamov and A. V. Sadykov, "Periodic shock waves in a gas," Izv. Akad. Nauk SSSR, Mekh. Zhidk. Gaza, No. 2 (1970). M. P. Mortell and B. R. Seymour, "A finite-rate theory of quadratic resonance in a closed tube," J. Fluid Mech., 112, 411 (1981).

Analogy between density stratification and rotation effects

Abstract: 7. L. T. Chernyi, "Uniform flow of electrified aerosols carrying a unipolar charge in an accelerating electric field," Dokl. Akad. Nauk SSSR, 273, No. 3 (1983). 8. L. I. Sedov, Mechanics of Continuous Media [in Russian]T 3rd ed., Vols. 1 and 2, Nauka, Moscow (1976). 9. P. V. Vorob'ev, "Method for investigating the operating efficiency of aerosol charging devices," in: Reports at the Scientificotechnical Conference on the NIR, Results for 1966-1967 [in Russian], Moscow Power Institute (MEI), Moscow (1967). i0. L. M. Levin, Investigations in the Physics of Coarsely Dispersed Aerosols [in Russian], Izd. Akad. Nauk SSSR, Moscow (1961). ii. S. P. Belyaev, N. K. Nikiforova, V. V. Smirnov, and G. I. Shchelchkov, Electron-Optical Methods of Investigating Aerosols [in Russian], Energoizdat, Moscow (1981). ANALOGY BETWEEN DENSITY STRATIFICATION AND ROTATION EFFECTS V. A. Vladimirov UDC 532.5.51+532.5.527 The resemblance (analogy) between the properties of rotating and density-stratified flows was first noted by Rayleigh in 1916 [i]. Since that time, a whole series of studies have been published in which this analogy is successfully employed to solve problems of wave theory and stability theory and to describe secondary regimes and turbulence. Some of these achievements are reviewed in [2, 3]. Although the successes achieved in using the analogy to obtain new results are impor- tant, our general understanding of the question is unsatisfactory. One problem is the dis- connectedness of the examples with references to which the analogy has been demonstrated. The degree of proximity on the basis of which results from the two domains are considered to be analogous varies from identicalness to very distant similarity. There has been no classi- fication of the examples of the analogy on the basis of general principles. The limits of applicability of the analogy remain unclear. The present study is an attempt to clarify these points. From the most general standpoint, the analogy between stratification and rotation ef- fects is a consequence of the known principle of mechanics which states that following tran- sition to the corresponding moving frame of reference any part of the true acceleration of an object can be regarded as a "body force" field. This approach is attractive because of its simplicity and universality. However, it turns out that in all nontrivial cases it is useless owing to the velocity dependence of the "body force" field. A good example is pro- vided by the equations of motion of a fluid written in a rotating coordinate system. Here the Coriolis force has to be taken as the "body force." Clearly, the introduction of "body forces" of this sort cannot give any basis for transposing the known results for a uniform gravitational field to a new domain. At the same time, there are more subtle and also more productive means of explaining the analogy. At present, the only possible way of unifying the theories is mathematical. The motions of a rotating and a stratified fluid will be analogous if they are governed by equations of similar form. The degree of similarity must be such that the description of a certain class of motions in one field makes an important contribution to the solution of a related problem in the other. Given this approach, the analogy question reduces to the prob- lem of classifying the corresponding differential equations. In general form this problem is extremely complex. The present study offers several examples illustrating the possi- bility of progressing along this path. Two levels of analogy, differing considerably with respect to the rigorousness of the requirements, are examined: i) the level of similarity of the initial nonlinear equations of motion of the rotating and stratified fluids; 2) the similarity of the linearized equations Of motion or their corollaries (e.g., spectral problems for linear waves and stability theory). Comparison of the equations makes it possible to state that the properties of the mo- tions of a rotating fluid are, generally speaking, much more complex than those of a strati- Novosibirsk. Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 58-68, May-June, 1985. Original article submitted March 22, 1984. 0021-8944/85/2603-0353509.50 9 1985 Plenum Publishing Corporation 353

Diffusion of a strong magnetic field in a dense plasma

Abstract: The authors consider the plane diffusion of a transverse magnetic field from a vacuum into a dense plasma in the collisional regime. A magnetic pinch discharge on the surface of an insulator can be considered as a special case of diffusion in a plasma of infinite density. The authors consider strong magnetic fields such that the plasma can be assumed to be completely ionized. The diffusion of a magnetic field in a hydrogen plasma at small values of the time is discussed.

Hydrodynamic drag of a ball containing a conduction-type source of electromagnetic fields

Abstract: This paper presents the results of numerical experiments using a conduction source in the regime of internal source operation It is confirmed that the total drag of a self-moving sphere can be less than its classical value The example of such a flow permits the assertion that the internal source EBF possess the capability of reducing the hyrodynamic drag of small span bodies

Electrical conductivity of shock compressed condensed argon at pressures from 20 to 70 GPa

Abstract: This paper measures the distribution of sigma in liquid argon behind a plane steadystate shock wave using the two-probe method. A diagram of the experimental equipment is shown which illustrates the plane shock wave generator, explosive charge, aluminum of iron striker plate, screen, dielectric insert, and other features of the apparatus. The change in sigma with duration of the material's stay in the compressed state indicates the absence of thermodynamic equilibrium in the argon near the shock wave front.

Propagation of stress waves in layered media under impact loading (acoustical approximation)

Abstract: This paper analyzes the generation of stress waves in a planar layered medium under impact loading in the acoustical approximation and it explores the possibility of preventing scabbing. A model of an elastic layered medium is presented and an analysis of wave processes in the three-layer plate is discussed. The analysis given is useful in its simplicity for the understanding and on-line prediction of the wave pattern generated in impact or explosive loading of multilayer plates.

Exact equations and transport coefficients for a multicomponent gas mixture with a partially ionized plasma

Abstract: Molecular transport processes are governing in many problems associated with-the flow of high-temperature multicomponent gas mixtures. Thus, a flow with a partially dissociated and ionized multicomponent gas is realized in problem of viscous heat-conducting gas flow around bodies in practically the whole flow domain outside the bow shock on the most heatstressed section of the trajectory, where convective heat transfer predominates, during entry in the atmosphere of planets of the solar system. Molecular transport processes in such a mixture govern directly the molecular heat and mass fluxes, the viscous friction force, as well as the rate of thermochemical destruction of the streamlined surface [i]. Transport processes play an important role in the flow of a weakly ionized plasma in a MHD generator [2], gas-phase nuclear reactors [3], and other problems. Consequently, a sufficiently rigorous and complete study of the behavior of the transfer coefficients in a broad temperature and pressure range is a problem of practical importance, and even more so since experimental investigations of multicomponent plasmas at high temperatures are related to great complexities in the diagnostics. It is also important to note that a study of all the necessary properties of a complete set of transfer coefficients has not been performed up to now because of the complexity of the appropriate formulas given by the kinetic theory of gases in the exposition in [4]. Of the experimental papers, [5-7] should be noted, in which the investigation of certain transfer properties of air, nitrogen, hydrogen, and argon was performed (mainly the heat conduction and viscosity coefficients only). Numerical computations were carried out in [8-11] for the transport properties of ionized gases by kinetic theory methods [4] with high approximations taken into account in a polynomial expansion of the distribution functions in Sonin polynomials. However, for flows of chemically equilibrium hightemperature gases for which effective coefficients are introduced in the hydrodynamics equations with additional terms associated with component transfer, heat liberation in reactions, and the use of quasineutrality conditions of the ionized mixtures taken into account (a strict determination of the complete set of effective transfer coefficients is given in [12, 13]), computations of all the effective coefficients in the hydrodynamics equations have never been performed successively. Up to now there is not sufficient information in the literature about the influence of any coefficient in any element temperature, pressure, and concentration range, nor about the role of taking account of high approximation in the computation of the transport coefficients for determining the heat flux, the component diffusion fluxes, and the viscous friction force [14].