Natural Convection in Porous Media

When the temperature of the saturating fluid phase in a porous medium is not uniform, some flows induced by buoyancy effects may occur. Commonly called free or natural convective movements, these flows depend on density differences due to temperature gradients and boundary conditions. Generally speaking, convective movements which tend to homogenize the whole fluid volume where they take place have two main effects: produce a non-uniform insitu temperature distribution characterized by hot and cold zones, and increase the overall heat transfer.Due to its numerous applications in geophysics and energy-related engineering problems, natural convection in porous media has been receiving increased interest over the last few decades (1,2).In this review, we deal mainly with the presentation of fundamental results obtained through the study of this phenomena in dispersed saturated porous media. Beginning with the formulation of basic equations and boundary conditions, we then successively review:first, the results concerning natural convection in homogeneous isotropic porous layers of wide lateral extent in horizontal or inclined positions,second, the studies on natural convection in confined porous media, i.e., when the lateral extent of the layer is of the same order of magnitude so that the thickness and the lateral thermal boundary effects are taken into account,and finally, the problems related to natural convection in more complex configurations, such as anisotropic porous layers or porous layers saturated by a fluid of non-constant properties.