ABSTRACT

The effects of variation (in the transverse direction, in layers) of permeability and thermal conductivity, on fully developed forced convection in a parallel-plate channel filled with a saturated porous medium, is investigated analytically on the basis of a Brinkman model, for the case of isoflux boundaries and a two-step variation. The results demonstrate that the effect of permeability variation is that an above-average permeability near the walls leads to an increase in Nusselt number, and this is explained in terms of variation in the curvature of the temperature profile. This effect of permeability variation becomes less important as the Darcy number increases. The effect of conductivity variation is more complex; there are two opposing effects and the Nusselt number is not always a monotonic function of the conductivity variation. This effect of conductivity variation retains its importance as the Darcy number increases.