Effect of an impermeable inclusion in an irrigated soil layer on seepage from a channel

In [1] plane steady seepage from a channel through a soil layer into an underlying unpressurized formation with an impermeable inclusion at the top was investigated in the case of constant uniform infiltration to the free surface. The results of numerical calculations are presented and the effect of the physical parameters of the model on the principal seepage characteristics is analyzed. The limiting cases of flow in the absence of the following factors are considered: inclusion [2], channel [3], channel and backwater [4], and backwater and infiltration [5]. A related scheme, the solution for which is obtained from the relations established, but outside the range of the limitation for one of the mapping parameters, is studied.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 71–76, September–October, 1990.The author wishes to thank P. Ya. Kochina for her interest and useful advice.     

Ground water regime in an irrigated soil layer with lower lying strongly permeable pressure level

A solution is found to the problem of planar pressureless steady filtration from a system of equidistance channels of the same thickness through a soil layer to a lower lying pressure level in the case of uniform infiltration (evaporation) to the free surface. The unique solvability of the system of equations for the two unknown transformation parameters is established. The filtration flow rate from a channel is investigated analytically as a function of the infiltration intensity and the magnitude of the backwater.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 168–174, March–April, 1979.I thank N. S. Kolodei for assistance in the calculations and the simulation.     

Systematic drainage of irrigated soils underlain by an impermeable layer

Problems of flow through porous media in which irrigation and drainage are simultaneously taken into account are very often encountered in connection with reclamation projects in arid zones. This article investigates the percolating flow in a soil of finite thickness under conditions of seepage and horizontal closed drainage. The soil is drained by a system of horizontal parallel equidistant circular pipes buried at the same depth. It is assumed that the drains are completely full of water; the pressure head in the soil along the line of contact with the drain is equal to the elevation of its upper point, at which there is no excess pressure. At the surface of the soil the moisture content is constant. This may be the result of a nonuniform irrigation rate distribution. If the irrigation is uniform, the surface layer of soil is nonuniformly moistened: maximum saturation, often supersaturation, occurs midway between the drains, while over the drains the soil is practically dry. The corresponding problem of steady state percolating flow reduces to a boundary-value problem of the theory of analytic functions, by solving which it is possible to determine the irrigation rate distribution needed to ensure uniform humidity of the soil surface. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 66–71, November–December, 1986.     

Filtration of ground waters with drainage flushings of a layer of soil with an impermeable base

Various investigators have recently taken up the question of developing a practical and effective technology for the drainage washing of saline soils [1–6]. As an alternative to continuous flooding with the nonuniformity inherent in this method and the resulting low degree of washing, it is proposed to differentiate the duration of the flooding of individual sectors of the area being washed, taking account of their distance from the drains. This point of view is presented most completely in [3], in which an analysis is made of washing under field conditions. Some of the results of this work are justified theoretically below.     

Infiltration on a strip in the presence of an inclined impermeable horizon

The author examines the effect of infiltration, acting on a strip, on the ground water level for unbounded and semibounded one-dimensional flow models, when the soil is homogeneous and the impermeable horizon has a slight tilt.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 11, No. 2, pp. 139–143, March–April, 1970.     

Flow stability in the Ekman layer on a permeable surface

Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 168–170, November–December, 1991.     

Effect of a permeable partition on convective instability of a horizontal liquid layer

We consider the effect of a thin permeable partition on the static stability of a horizontal liquid layer heated from underneath. The permeable partition is assumed to be plane and situated parallel to the boundary planes in the center of the layer. The resistance of the partition to the flow of liquid from one part of the layer to another leads to an increase in the static stability. We investigate the dependence of the minimum critical Rayleigh number-on the resistance of the partition and the form of the critical motions.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 157–159, January–February, 1977.     

Three-wave interactions between disturbances in the hypersonic boundary layer on impermeable and porous surfaces

The interaction between disturbances in the hypersonic boundary layer on impermeable and porous surfaces is considered within the framework of weakly-nonlinear stability theory. It is established that on the impermeable surface nonlinear interactions between different waves (acoustic and vortex) occur in the parametric resonance regime. The role of pumping wave is played by a plane acoustic wave. The nonlinear interactions take place over a wide frequency range and can lead to the packet growth of Tollmien-Schlichting waves. On the porous surface the analogous interactions are fairly weak and result in a slight decay of the acoustic mode and a slight amplification of the vortex mode. This leads to the dragging out of the laminar flow regime and the regions of linear disturbance growth. In this situation the low-frequency spectrum of the vortex modes may be filled on account of the nonlinear processes occurring in the three-wave systems between the vortex components.     

Experiments on double-diffusion in a composite system comprised of a packed layer of spheres and an underlying fluid layer

In this paper an experimental study is reported on the problem of double-diffusion in a composite system comprised of a liquid-saturated packed layer of spheres and an underlying clear (of solid matrix) fluid layer. The liquid is a mixture of water and ammonium chloride. The initial species concentration of the porous layer is linear and stable and of the clear liquid layer uniform. The system is initially isothermal and it is suddenly cooled from above. The study investigates the evolving temperature and flow fields in the system by utilizing direct temperature measurements as well as holographic interferometry visualization of the density field. The effect of the thermal Rayleigh number, the species Rayleigh number, the thermal conductivity of the beads constituting the porous matrix, and the height of the porous matrix on the evolving temperature and flow fields are determined. Comparisons of the experimental results to the predictions of an existing theoretical model define the limitations of this model and the time domain in which the model performs acceptably well. The findings of this study are relevant to double-diffusion phenomena occuring in the mixed phase and liquid regions of solidifying binary mixtures.     

Formation of the impermeable layer in the process of methane hydrate dissociation in porous media

The problem of decomposition of methane hydrate coexisting with water in a highpermeability reservoir is considered. The asymptotic solution is obtained for the decomposition regime in the negative temperature domain. Energy estimates presented show that an impermeable layer saturated with a hydrate-icemixture can be formed in reservoirs with initial positive temperature. The mathematical model of the process of hydrate decomposition is formulated under the assumption on the presence of such a layer in a high-permeability reservoir. In this case the problem is reduced to a purely thermal problem with two unknown moving boundaries. The water-ice phase transition takes place on the leading boundary, while hydrate dissociates at negative temperatures on the slower boundary. The conditions of existence of the layer saturated with a hydrate-ice mixture which is implemented in reservoirs with the high hydrate content are investigated.     

Effect of gas compressibility on the stability of a boundary layer above a permeable surface at subsonic velocities

In the present study we investigate the stability of a boundary layer for the condition that the velocity perturbations at the permeable surface are nonzero. The stability for the boundary layer of an incompressible liquid in such a formulation was considered in [1]. For the case of subsonic velocities the effect of compressibility on the flow inside the boundary layer is weak, and in the present article this effect was neglected. The unsteady flow in narrow pores of a permeable covering depends strongly on the compressibility of the gas. Therefore, in the derivation of the relation connecting the pressure oscillations at the permeable surface with the oscillations of the flow through it, the effect of the compressibility was taken into consideration. It is shown that the boundary conditions, and therefore also the stability of the boundary layer at the permeable surface, depend considerably on the Mach number, even for a subsonic exterior flow.     

Displacement in the turbulent boundary layer on a permeable plate with supercritical injection

The displacement thickness in a turbulent boundary layer is determined for supercritical injection parameters. Experimental relations between the displacement thickness and the injection parameter are obtained for air, helium, and freon-12 injected into air.     

Combined heat transfer in a boundary layer of a selectiviely absorbing medium on a permeable plate under the conditions of intense radiation heating

Results of a numerical study of unsteady radiative-convective heat transfer in a boundary layer on a thermally thin permeable plate in the presence of intense radiation heating from outside are reported. The conjugate formulation of the problem takes into account the thermal interaction between the plate and an external gas flow. We consider a turbulent flow of an emitting-absorbing medium with the selective character of absorption. Calculation results are analyzed with a view for clarifying the influence of the governing parameters, namely, the relative temperature of an external radiation source, the Stark number, and the injection parameter. The possibility of inversion of a convective heat flux on the plate under the conditions of high-level external radiation is found. Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Sciences, Novosibirisk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 5, pp. 126–133, September–October, 1998.     

Effect of heat flux on boundary layer flow under rotating conditions

The boundary layer flow behaviour in a smooth rotating channel with heated walls is measured by particle image velocimetry (PIV). To simulate the real operation environment of an internal coolant channel in a turbine blade, airflow is analysed in a rotating channel, whose four walls are uniformly heated by Indium Tin Oxide (ITO) glass. The flow is measured in the middle plane of the rotating channel with a Reynolds number equal to 10000 and rotation numbers ranging from 0 to 0.52. The results are presented for the boundary layer flow behaviour with and without heated thermal boundary conditions. The buoyancy force generated by the heated walls influences the flow behaviour under rotating conditions. Separated flow occurs, which substantially influences the turbulent flow behaviours. Sometimes, this buoyancy force can determine the flow behaviours. The results also showed that the displacement thickness and the momentum loss thickness present new changes at different radius positions due to the heated thermal boundary conditions. The displacement thicknesses of both the leading and trailing sides with heated walls are both thicker than those of the leading and trailing sides without heated walls. Then, the difference of the boundary layer thickness between these two cases increases with the increase of rotation number. For momentum loss thickness, a sharp drop happens when the rotation number increases to a certain value. At the large radius position, the drop in momentum loss thickness is much greater than that in the small radius position.     

Comparison of approximate and exact models of leaching in the presence of a horizontal impermeable layer

In [1], the present author investigated an approximate model of two-dimensional flow in the case of leaching of soil in the presence of an impermeable layer when the depression curve is replaced by a fixed horizontal boundary. Later [2] the problem was solved with allowance for and the finding of the depression curve. In the present paper, the flow characteristics in approximate and exact formulations are compared for several variants on the basis of the results of calculations made on the basis of the obtained solutions.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza., No. 3, pp. 168–173, May–June, 1982.I thank N, S. Kolodei for assistance in the calculations.     

Prediction of salt conditions in irrigated soils in the presence of drainage

The equations of convective diffusion are solved for two flat layers, using the method of finite integral transformations. Exact solutions are obtained to the problem in the presence of a descending or ascending filtration flow.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 113–117, November–December, 1972.