The effect of variable viscosity on boundary-layer heat transfer in a porous medium

In this work we present a theoretical analysis of forced-convection heat transfer over a flat surface imbedded in a saturated porous medium, considering that the viscosity of the fluid varies with temperature. The velocity and temperature profiles are described by means of a similarity solution. The effect of viscosity variations is quantified for the case of a fluid whose dependence of viscosity on temperature is linear. Illustrative results indicate that, for liquids, this effect should be taken into account, even for relatively low temperature gradients. This confirms experimental observations made in previous works.