Effect of variable viscosity on non-Darcy free or mixed convection flow on a horizontal surface in a saturated porous medium

The effect of the variable viscosity is considered for non-Darcy free or mixed convection boundary-layer flow on a horizontal surface in a saturated porous medium. The viscosity of the fluid is assumed to be an inverse linear function of the temperature. The partial differential equations governing the nonsimilar flow have been solved numerically using an implicit finite-difference scheme developed by Keller. For the forced convection flow, the self-similar solution exists for the constant free stream velocity and for isothermal and non-isothermal walls, but for the free convection flow self-similar solution exists for only lambda = 1/2 (non-isothermal wall). (C) 2001 Elsevier Science Ltd.