On the Theory of Acoustic Scanning of Damage to Underground Pipelines

Acoustical Physics - The paper studies the evolution of a pulsed signal initiated by the pushing of a cylindrical piston and propagating through a stationary fluid filling a buried pipeline with an...     

On the Dynamics of Harmonic Filtration Waves in a Hydraulic Fracture Perpendicular to the Wellbore

Acoustical Physics - The paper studies the propagation of low-frequency harmonic pressure waves in a fracture formed by hydraulic fracturing and perpendicular to the wellbore in a porous and...     

Acoustic waves in a liquid with a bubble screen

In this work, certain peculiarities of the dynamics of pressure waves in a liquid containing bubbles are studied. The specification of a model of bubbly liquids with regard to acoustic damping of the bubbles is considered. Our theoretical results are compared with experimental ones.Received: 30 June 2002, Accepted: 2 February 2003, Published online: 11 June 2003     

Forced nonlinear oscillations of a gas bubble in a large spherical flask (resonator) filled with a fluid

Radial oscillations of a gas bubble in a large spherical flask filled with a fluid are considered. We derive an equation of the change of the bubble radius by the known law of pressure variation at the boundary of the liquid volume (the law of motion of the piston) for a period of time during which, repeatedly reflected from the piston, the leading front of the reflected-from-the bubble perturbations reaches the bubble. For further calculations of the change of the bubble radius, recurrent relations which include the wave reflected from the bubble in the previous cycle and its subsequent reflection from the piston are obtained. Under harmonic action of the piston on the fluid-bubble system, a certain periodic regime with a package of bubble oscillations is established. Institute of Mechanics, Ural Scientific Center, Russian Academy of Sciences, Ufa 450000. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 5, pp. 77–87, September–October, 1998.     

Two-Dimensional Pressure Waves in a Fluid with Bubbles

The specific features of wave evolution in a fluid with a finite bubble zone are studied. The two-dimensional effects are taken into account. The results for two-dimensional wave evolution in a uniform bubbly fluid are also presented.     

Self-similar problem of decomposition of gas hydrates in a porous medium upon depression and heating

We consider the specifics of decomposition of gas hydrates under thermal and depressive action on a porous medium completely filled with a solid hydrate in the initial condition. The existence of volumetric-expansion zones, in which the hydrate coexists in equilibrium with water and gas, is shown to be possible in high-permeable porous media. The self-similar problems of hydrate decomposition upon depression and heating are studied. Ii is shown that there are solutions according to which hydrate decomposition can occur both on the surface of phase transitions and in the volumetric region. We note that, in the first case, decomposition is possible without heat supply to a medium and even with heat removal. Institute of Mechanics of Multiphase Systems, Siberian Division, Russian Academy of Sciences, Tyumen' 625000. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 111–118, May–June, 1998.     

Allowance for nonstationary heat and mass transfer in the propagation of small perturbations in a liquid with bubbles

The propagation of small perturbations in a liquid with vapor-gas bubbles is studied. Heat and mass transfer between the phases is taken into account on the basis of the exact equations of heat conduction and diffusion. The aim of the present investigation is to make more precise the results of an earlier paper [1] of the author and verify the applicability of using fixed coefficients of heat and mass transfer for nonstationary heat and mass transfer between a pulsating bubble and the liquid.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 157–162, July–August, 1979.     

Dynamics of detonation waves in an annular layer of a round pipe

The dynamics of axisymmetric detonation waves in a round pipe containing an annular near-wall bubble layer with a combustible gaseous mixture are studied. The situations in which within the annular layer there are a pure liquid or a bubbly mixture with an inert (unexplosive) gas are considered.     

Calculation of Heavy Gas Spreading Over the Earth Surface by a Three-Dimensional Model

A mathematical model is constructed for motion of a heavy gas along the underlying terrain on the basis of equations of gas dynamics with allowance for the force of gravity, transfer by air masses, and turbulent diffusion. With the use of the method of coarse particles, the time dependences of the coordinates of the fore front, upper boundary, and volume of the cloud of a heavy gas in the presence and absence of wind are analyzed. It is shown that turbulent diffusion leads to a linear increase in cloud volume in time. Three-dimensional shapes of the heavy gas cloud are obtained for various ambient conditions. It is shown that, despite diffusion, the heavy gas spreads predominantly along the underlying terrain.     

Explosive discharge of a gas-saturated liquid from channels and tanks

A mathematical model for the discharge of a gas-saturated liquid from cylindrical channels is developed. Two limiting cases of linear and quadratic, relations between the flow friction force and the flow velocity are considered. It is established that the process of evacuation, from a semi-infinite channel consists of two stages. In the initial stage, the flow drag can be ignored, and the process of discharge is described by a Riemann wave solution. For the next stage, in which inertia is insignificant, nonlinear equations are obtained and self-similar solutions are constructed for them. The problem of flow through a slot in a tank of finite volume is solved. It is shown that the discharge proceeds either in a gas-dynamic choking regime or in a subsonic regime, depending on the conditions inside the tank and at the outlet. Examples of numerical calculations are given. Institute of Mechanics, Ufa Scientific Center, Russian Academy of Sciences, Ufa 450000 Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 1, pp. 64–73, January–February, 1999.