NON-DARCY MIXED CONVECTION FROM A VERTICAL PLATE IN SATURATED POROUS MEDIA-VARIABLE SURFACE HEAT-FLUX

Nonsimilarity solutions for non-Darcy mixed convection from a vertical impermeable surface embedded in a saturated porous medium are present ed for variable surface heat flux (VHF) of the power-law form. The ent ire mixed convection region is divided into two regimes. One region co vers the forced convection dominated regime and the other one covers t he natural convection dominated regime. The governing equations are fi rst transformed into a dimensionless form by the nonsimilar transforma tion and then solved by a finite-difference scheme. Computations are b ased on Keller Box method and a tolerance of iteration of 10(-5) as a criterion for convergence. Three physical aspects are introduced. One measures the strength of mixed convection where the dimensionless para meter Ra-x/Pe(x)(3/2) characterizes the effect-of buoyancy forces on the forced convection; while the parameter Pe(x)/Ra-x(2/3) characteri zes the effect of forced flow on the natural convection. The second as pect represents the effect of the inertial resistance where the parame ter K'U-infinity/nu is found to characterize the effect of inertial fo rce in the forced convection dominated regime, while the parameter (K' U-infinity/nu)(Ra-x(2/3)/Pe(x)) characterizes the effect of inertial force in the natural convection dominated regime. The third aspect is the effect of the heating condition at the wall on the mixed convectio n, which is presented by m, the power index of the power-law form heat ing condition. Numerical results for both heating conditions are carri ed out. Distributions of dimensionless temperature and velocity profil es for both Darcy and non-Darcy models are presented.