Papers by Anvar Gubaidullin
Solid Mechanics and Its Applications
Surface Rayleigh waves in porous media have been the subject of a number of investigations before... more Surface Rayleigh waves in porous media have been the subject of a number of investigations before (Dobrin, [1]; Press, Healy, [2]; Macdonald, [3]; Deresiewicz, Rice, [4]; Takeuchi, Saito, [5]; White, [6]; Liu Philip, Wen Jiangang, [7]). In the present paper the features of the Rayleigh waves propagating along the free surface of a porous medium saturated with liquid are investigated by means of two-velocity, twostress tensor model. The dispersion relation is obtained. The frequency dependence of phase velocity, linear decrement of attenuation and coefficients exhibiting damping of amplitude with depth for monochromatic, waves are studied. The pattern of deformation of the near-surface layer during Rayleigh wave propagation is considered.
Journal of Applied Mechanics and Technical Physics
ABSTRACT
The effects of amplification are theoretically and experimentally obtained in different media: ga... more The effects of amplification are theoretically and experimentally obtained in different media: gas-liquid and vapour-liquid mixtures, clay suspension, polymer solutions, etc. All these effects have the same reason: the existence of local deformational inertia which is common for all systems containing gas or vapour bubbles. In the paper, the detailed investigation of such a phenomenon is presented using the numerical methods.
Porous Media: Theory and Experiments, 1999
The features of propagation of longitudinal and transverse waves (LW and TW) in fractured porous ... more The features of propagation of longitudinal and transverse waves (LW and TW) in fractured porous medium (FPM) saturated with liquid are investigated by methods of multiphase mechanics. The mathematical model of FPM accounting for inequality of velocities and pressures of liquid in pores and fractures, liquid mass exchange and nonstationary interaction forces is developed. Processes of monochromatic wave propagation are studied. The dispersion relation is obtained and the effect of model parameters on wave propagation is analysed. It is established that one transverse and three longitudinal waves propagate in FPM saturated with liquid. The fastest LW is a deformational wave and the two others are filtrational. Filtrational waves attenuate much stronger than deformational and transverse waves. Distinction of velocities and pressures in liquid in various pore systems provides an explanation for the existence of the two filtrational waves in porous medium with two different characteristic sizes of pores.
Doklady Physics - DOKL PHYS, 1996
Transport in Porous Media, 1996
The features of propagation of one-dimensional monochromatic waves and dynamics of weak perturbat... more The features of propagation of one-dimensional monochromatic waves and dynamics of weak perturbations with axial and central symmetries in liquid-saturated porous medium are investigated. Non-stationary interaction forces and viscoelastic skeleton characteristics are taken into account. The research is carried out within the two-velocity, two-stress tensor model by applying methods of multiphase media mechanics. The system of equations is solved numerically
Transport in Porous Media, 1992
The peculiarity of linear and nonlinear wave propagation in porous media saturated with liquid or... more The peculiarity of linear and nonlinear wave propagation in porous media saturated with liquid or gas has been investigated by the methods of multiphase media mechanics. It has been shown that for the analysis and interpretation of experimental data, it is expedient to build models taking into account the nonstationary powers of interaction between the solid and liquid phases and the viscouselastic behaviour of the porous media skeleton. Inertia and inertia-viscous powers principally influence wave attentuation in porous media. Two interphase mechanisms of momentum transfer (two stress tensors — in the solid phase and liquid) lead to two types of waves. Attenuation is determined not only by interphase friction, but also by dissipation resulting from intergrain friction in the solid phase, the influence of which multiplexly exceeds the liquid viscosity influence. The real decrement of attenuation may exceed the sphere restricted by the limiting curves corresponding to the frozen and equilibrium schemes of intergrain deformation. The attenuation of momentum perturbation has been studied. The method of discrete Fourier transform has been used. The analysis of experimental data contained in the literature and their comparison with the results of calculations has been carried out.
Pharmaceutical Chemistry Journal, 2007
Data of IR, UV, and NMR (31 P, 1 H, 13 C) spectroscopy, X-ray crystallography, and quantum chemic... more Data of IR, UV, and NMR (31 P, 1 H, 13 C) spectroscopy, X-ray crystallography, and quantum chemical calculations are presented for phosenazid and CAPAH molecules possessing psychotropic properties. In comparison to phosenazid, CAPAH exhibits a broader spectrum of neurotropic activity, which can be related to the presence of the P1-O3 polar ester bond and, therefore, a higher reactivity of this molecule in metabolic processes.
A method is described for investigating unsteady undulatory leakage of a saturated liquid from a ... more A method is described for investigating unsteady undulatory leakage of a saturated liquid from a ruptured high-pressure pipeline. The motion of the liquid-vapor mixture is described via a homogeneous model of a one-velocity saturated stream. The initial differential equations are transformed to a form that can be conveniently integrated by a finite difference scheme with maximum computer-time savings. The method is used to compute leakage of saturated water at high temperature and pressure from a ruptured pipeline.
The Journal of the Acoustical Society of America, 2004
We investigate numerically the frequency dependence of the velocities and damping coefficients of... more We investigate numerically the frequency dependence of the velocities and damping coefficients of the various surface waves that exist on the interface between a fluid half-space and a half-space of a water-saturated porous Biot medium including viscous attenuation. We find that there is a f1 frequency dependence for pure radiation damping. For a sealed-pore surface configuration, the pseudo-Stoneley wave is radiating at high frequencies, but becomes purely viscosity-damped as frequency decreases. For the open-pore surface configuration, the pseudo-Rayleigh wave remains radiative over the entire frequency domain and is damped by a combination of radiation and viscous fluid–solid interaction. It is also found that the pseudo-Rayleigh wave may even become faster than the bulk shear mode, at low frequencies.
Journal of Applied Mechanics and Technical Physics, 1978
In recent years many theoretical and experimental reports have been published on the investigatio... more In recent years many theoretical and experimental reports have been published on the investigation of shock waves in liquids containing gas bubbles [1-11]. The reports on the experimental level are devoted to the investigation of the structures of compression waves in mixtures with rather large bubbles (~ 1 mm) [4-6, 9]. Because of the considerable lengths of the relaxation zones for waves in such mixtures (~ 1 m), comparable 'with the lengths of the shock tubes, the waves observed in [4-6, 9] were nonsteady, as a rule. This was first noted in [8], where the necessity of enlisting the nonsteady theory in the analysis of experimental data was pointed out (up to then only steady wave configurations were studied in the theoretical reports [1, 3-5, 8, 9]). The propagation of a weak nonsteady wave was first studied in [7] on the basis of the Burgers-Korteweg-de Vries model equation. The report [10] is devoted to a description of the general approach to the investigation of nonsteady waves in bubble media. In the present report principal attention is paid to questions of the concrete definition of the model of the dynamic behavior of the medium and to a discussion of recent results. w To describe the nonsteady motions of mixtures of liquids and gas bubbles we use the methods of the mechanics of a continuous medium, assuming that the characteristic linear scales of the flow are much larger than the sizes of the bubbles and the distances between them. We construct the model of the dynamic behavior of the mixture with the following simplifying assumptions:
Fluid Dynamics, 1977
Special aspects of the transmission of transient waves through gas mixtures carrying suspended so... more Special aspects of the transmission of transient waves through gas mixtures carrying suspended solid particles of chemically inert substances are examined. The influence of the parameters of the gas suspension on the conditions governing the occurrence of transient processes is discussed. The interaction of shockwaves with a dust-laden half-space is considered. The results of calculations relating to the decay of an arbitrary discontinuity during the reflection of a shock wave from a wall are presented.
Doklady Physics, 2000
ABSTRACT
Computational Mechanics, 2003
The procedure based on the modified two-step Lax-Wendroff scheme has been suggested for calculati... more The procedure based on the modified two-step Lax-Wendroff scheme has been suggested for calculation of one-dimensional non-stationary motion of porous media described by the mathematical two-velocity model with two stress tensors. Results of computer modeling of the processes of passing the boundary between gas and porous medium by air shock wave and the reflection from rigid wall covered by the porous layer are presented.
Combustion, Explosion, and Shock Waves, 2000
... inedium mid shows (lissil)~ttive 1)rol)erties, one can exI)ect that the waves will dmu t) aft... more ... inedium mid shows (lissil)~ttive 1)rol)erties, one can exI)ect that the waves will dmu t) after several reflections, and an os(:illating total-stress ('rowe con-verging to the 1)ressure upon refle('tion of the shoe'k wave ... The ('haracter of the chan~e in the total stress at the ol)st;u:le (Fig. ...
High Temperature, 2015
Numerical investigation of vibration action on a cylindrical cavity filled with a viscous perfect... more Numerical investigation of vibration action on a cylindrical cavity filled with a viscous perfect gas was performed. The boundaries of the cavity were maintained at a constant temperature equal to the initial one. The problem was solved in the two dimensional axisymmetric statement. The numerical solution to the problem is compared with the analytical solution in the linear approximation. The nonlinear effects are described.
Thermophysics and Aeromechanics, 2014
The influence of the vibrational action on a cylindrical cavity filled with a viscous perfect gas... more The influence of the vibrational action on a cylindrical cavity filled with a viscous perfect gas is studied numerically. The problem is solved in a two-dimensional axisymmetric statement. The cavity walls are thermally insulated. The numerical solution of the problem is compared with the analytic one in the linear approximation. The nonlinear effects and the non-one-dimensional effects are described.
Uploads
Papers by Anvar Gubaidullin