Boiling in a porous bed

Experimental observations of the heat generation rate at which a porous bed dries out have been made for bed particle sizes ranging from 245 to 4,783 microns in beds up to 40 cm deep with different coolants. The governing mechanisms are identified and used to develop models of the observed phenomena.     

Boiling in a porous bed

Experimental observations of the heat generation rate at which a porous bed dries out have been made for bed particle sizes ranging from 245 to 4,783 microns in beds up to 40 cm deep with different coolants. The governing mechanisms are identified and used to develop models of the observed phenomena.     

Dynamic model of liquid motion in a porous medium

A theory which takes account of the role of inertial effects in liquid motion in a porous medium is developed. For a compressible liquid, not only the hydrodynamic equations but also the thermodynamic transfer equation are formulated. The initiation, propagation, and dissipation characteristics of eddy motion are considered. Matching conditions at the interface between the media and boundary conditions are obtained. An approximate formulation of the problem is given, isolating in the porous medium a basic flow region in which the classical Darcy law is valid. As an illustration, weakly perturbed liquid flow in a plane channel with an insert of porous material is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 89–95, November–December, 1978.     

Motion of a viscoplastic liquid in a porous inhomogeneous medium

Equations of motion are derived for a viscoplastic liquid in a nonuniform medium of type 2 (piecewise uniform) or type 3 (with a variable filtration coefficient) [1] on the assumption that the motion is of steady-state type. Solutions are presented for a parallel flow and a flow with axial symmetry.     

Gas pressure equalization in a porous medium filling a pipe with a closed end under shock loading

The problem of gas pressure equalization in a porous medium filling a pipe with a closed end under shock loading is solved. In this case, the initial filtration velocity behind the shock wave should be specified as initial data, in addition to the shock pressure. It is shown that the shock decays at a finite distance and pressure equalization occurs in a finite time. Approximate submodels of discontinuous and smooth solutions are obtained.     

Thermophoresis particle deposition in a non-Darcy porous medium under the influence of Soret, Dufour effects

Thermophoresis particle deposition in free convection on a vertical plate embedded in a fluid saturated non-Darcy porous medium is studied using similarity solution technique. The effect of Soret and Dufour parameters on concentration distribution, wall thermophoretic deposition velocity, heat transfer and mass transfer is discussed in detail for different values of dispersion parameters (Ra _γ, Ra _ξ) inertial parameter F and Lewis number Le. The result indicates that the Soret effect is more influential in increasing the concentration distribution in both aiding as well as opposing buoyancies. Also, the non-dimensional heat transfer coefficient and non-dimensional mass transfer coefficient changes according to different values of thermophoretic coefficient k.     

Dissociation of hydrates in a porous medium under depressive effects

Institute of Multiphase System Mechanics, Russian Academy of Sciences, Siberian Division, Tyumen' 625000. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 36, No. 4, pp. 120–130, July–August, 1995.     

On the unsteady flow of a compressible liquid through a porous medium

Summary The unsteady flow of a compressible liquid in a porous medium can be described in terms of a non-linear partial differential equation for the liquid pressure or a linear differential equation for the density if gravitational effects are negligible. In gravitational flow fields the formulation yields non-linear equations for both density and pressure. A transformation is given which shows that in the absence of gravitational effects, the solution of the non-linear boundary value problem in terms of the pressure involves no more labour than the solution of the linear problem in terms of the density, contrary to a misconception in the petroleum literature. Furthermore this transformation offers in addition the solution to a heretofore unsolved problem in gravity flow.This research was supported in part by the Office of Naval Research under Contract Nonr-222(04).     

Equilibrium of a crack in a porous medium with injection of the filtering liquid

In connection with the exploitation of petroleum deposits, the article discusses the equilibrium of a porous medium with a crack under conditions of plane deformation, with the steady-state filtration of a liquid injected into the porous medium through a crack. It is assumed that the crack, which has initial zero dimensions, can become wider and longer with a rise in the pressure. The displacement of the sides of the crack is determined on the basis of the theory of elasticity, taking account of the deformation properties of a saturated porous medium. The stress and the displacement are expressed in terms of two analytical Muskhelishvili functions and the complex filtration potential. A change in the volume of the porous medium leads to a discontinuity of the displacements at the feed contour, and to distortion in the filtration region. For a circular stratum, the dimensions of the crack and the mass flow rate of the liquid are determined in the first approximation. The region of values of the pressure in which there exists a stable equilibrium state of the open crack and a steady-state flow of the liquid is found.     

Asymptotic analysis of surface waves at vacuum/porous medium and liquid/porous medium interfaces

Received November 1, 2001 / Published online February 4, 2002     

Temperature and pressure field visualizations in a porous medium dried in superheated steam

This work focuses on heat and mass transfers with phase change in porous media. The experimental analysis was carried out in an aerodynamic return-flow wind tunnel, with very small cylinders of cellular concrete. For the local analysis, the samples were fitted with thermocouples and pressure sensors. A method of temperature and pressure field visualization is developed to highlight the dynamics of transport phenomena. We show two specific phenomena: (1) liquid outflow generated by the overpressure and (2) vaporization of the water inside a two-phase zone that progressively pervades the sample.     

On the convective instability of a liquid in an inclined layer of a porous medium

In this paper we study the stability of the equilibrium of a liquid heated from below, wherein the liquid saturates a planar layer of a porous medium arbitrarily inclined to the direction of gravity. We consider the cases for which the boundaries of the layer are heat-conducting and also thermally insulated. In a horizontal layer with heat-conducting boundaries equilibrium is destroyed by perturbations of cellular structure [1], In a vertical layer the minimum critical temperature gradient corresponds to perturbations of plane-parallel structure. The transition to cellular perturbations in the case of heat-conducting boundaries takes place at an arbitrarily small angle of inclination of the layer to the vertical. For the thermally insulated layer the crisis of equilibrium is connected with plane-parallel perturbations at all angles of inclination.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 127–131, May–June, 1973.The author thanks G. Z. Gershuni for stating the problem and his interest in the work.     

Enhancement of shock waves in a porous medium saturated with a liquid containing soluble-gas bubbles

Evolution of a moderate-intensity shock wave and its enhancement after reflection from a rigid surface embedded in a porous medium are studied experimentally. The medium is saturated with a liquid that has bubbles of a soluble gas. A physical mechanism of shock wave enhancement in a saturated porous medium is proposed. Experimental data on the amplitude and velocity of reflected waves are compared with results of theoretical modeling. The process of gas bubble dissolution behind a shock wave is studied.