Effects of Wall Conduction and Darcy Number on Laminar Mixed Convection in a Horizontal Square Porous Channel

This paper investigates the effects of peripheral wall conduction and Darcy number on laminar mixed convection in the fully developed region of a horizontal square porous channel with a uniform heat input. Because of the combined effects on nonaxisymmetric channel configuration, buoyancy-induced secondary flow, and noninfinite wall conduction parameter, the flow and heat transfer characteristics are greatly affected by the peripherally nonuniform wall temperature distribution. A modified Darcy-Forchheimer-Ergun flow model in the porous medium and a finite-difference method are applied. Secondary flow patterns, isotherms, wall temperature distributions, the friction factor, and the Nusselt number are presented for a flow in the Darcian porous medium (Da→0) to a pure fluid flow (Da → ∞) with Kp = 10⁻⁴ − 10⁴, Gr = 0 − 10¹⁰, and Pr = 0.1, 0.73, 7.2, and 100. Wall temperature distributions and the Nusselt numbers are compared with existing experimental data.