The eect of porosity on natural convective ¯ow and heat transfer in a ¯uid saturated porous medium has been investigated using
Galerkin's ®nite element method. A generalised non-Darcy ¯ow model with porosity as a separate parameter is used. Results indicate
that the non-Darcy regime is highly sensitive to porosity changes. A variation of the order of 40% in the average Nusselt number
is possible with change in the porosity, for the Rayleigh and Darcy number ranges considered. Ó 1998 Elsevier Science Inc. All
rights reserved.