Nonsimilar solutions for non-Darcy mixed convection from a nonisothermal horizontal surface in a porous medium

The nonsimilar non-Darcy mixed convection adjacent to a horizontal surface in a saturated porous medium is analyzed. Nonsimilarity solutions are obtained for the case of variable surface temperature in the form T-w(x) = T-infinity + ax(n). The analysis is performed for the entire mixed convection regime which is divided into two regions. The first region covers the forced-convection-dominated regime and the second region covers the free-convection-dominated regime. The Darcy-Brinkman-Forchheimer equation is used as the momentum equation, and the effect of near-wall porosity variation is approximated by an exponential function. The effects of thermal dispersion and variable stagnant thermal conductivities are taken into consideration in the energy equation. Velocity and temperature profiles and local Nusselt numbers are presented for different governing parameters. Effects of non-Darcy flow phenomena on the heat transfer characteristics are thoroughly examined. (C) 1998 Elsevier Science Ltd. All rights reserved.