Natural convection in vertical enclosures containing simultaneously fluid and porous layers

Abstract

A numerical and experimental study is reported of natural convection in a vertical rectangular fluid enclosure that is partially filled with a fluid-saturated porous medium. Velocities, stresses, temperatures, and heat fluxes are assumed to be continuous across the fluid/porous-medium interface, and the conservation equations for the fluid and the porous regions are combined into a single set of equations for numerical solution. Thermocouples as well as a Mach-Zehnder interferometer are used to measure temperature distributions and infer fluid flow patterns within the fluid and the porous medium. For various test cells, porous-layer configurations and fluid-solid combinations, the model predictions show excellent agreement with the experimental measurements. It is found that the intensity of natural convection is always much stronger in the fluid regions, while the amount of fluid penetrating into the porous medium increases with increasing Darcy and Rayleigh numbers. The degree of penetration of fluid into the porous medium depends strongly on the porous-layer geometry and is less for a horizontal porous layer occupying the lower half of the test cell. If penetration takes place, the flow patterns in the fluid regions are significantly altered and the streamlines show cusps at the fluid/porous-medium interfaces. For a high effective-thermal-conductivity porous medium, natural convection in the medium is suppressed, while the isotherms bend sharply at the fluid/porous-medium interface.

Free convection of composite porous medium in a vertical channel

“…(20), (22), (24), and (26), the solutions for temperature and velocity for both the fluids in regions 1 and 2 using the boundary and interface conditions (27) to (30) …”

“…Several works have appeared on composite layer flows using these conditions or variant of them [7,22,23]. There are numerous other studies available on natural convection in vertical and horizontal enclosures containing various layers of porous media having different permeabilities (Beckerman et al [24] and references therein).…”

Darcian Natural Convection in Inclined Square Cavity Partially Filled Between the Central Square Hole Filled with a Fluid and Inside a Square Porous Cavity Filled with Nanofluid

“…Meanwhile, Beckermann et al (1987) studied natural convection flow and heat transfer between a fluid layer and a porous layer inside a rectangular enclosure. Natural convection heat and mass transfer in solidification was studied by Beckermann et al (1988). On the other hand, Chen and Chen (1989) investigated convective stability in a superposed fluid and porous layer when heated from below, while Le Breton et al (1991) examined heat transfer and fluid flow through fibrous insulation.…”

A numerical investigation of a buoyancy driven flow in a semi-porous cavity: comparative effects of ramped and isothermal wall conditions

“…In order to account for them in our present analysis, we have employed the widely used Brinkman model (often referred to in the literature as Darcy-Brinkman model) to describe the flow in the porous medium of high permeability. In fact, a number of researchers have strongly advocated the appropriateness of this model for high porosity bounded media (Beckermann et al, 1988;Hill and Straughan, 2009a,b;Neale and Nader, 1974;Nield and Bejan, 2006;Nishimura et al, 1986, Singh et al, 1993Singh et al, 2009;Straughan, 2002;Zhao et al, 2004). Porous materials with porosity close to unity are encountered in several industrial and geophysical applications.…”