MIXED CONVECTION FROM A VERTICAL PLATE IN POROUS-MEDIA WITH SURFACE INJECTION OR SUCTION

The problem of mixed convection along an isothermal vertical plate in porous media with uniform surface injection or suction is studied. The analysis deals with the entire regime of mixed convection by introducing a single parameter chi = [1 + (Ra(x)/Pe(x))1/2]-1, where chi = 1 corresponds to pure forced convection and chi = 0 to pure free convection. This chi parameter describes both buoyancy and forced flow effects. The nonsimilar variable xi = (upsilon0x/alpha)(Pe(x)1/2 + Ra(x)1/2)-1 represents the effect of injection (upsilon0 > 0 or xi > 0) or suction (upsilon0 < 0 or xi < 0) at the wall. The transformed nonlinear system of equations involving these parameters is solved using a finite difference method. Results are presented for temperature and velocity profiles, local wall shear stress, and local Nusselt number for the buoyancy assisting flow condition. It is found that suction increases, whereas injection decreases, the rate of heat transfer at the wall. Correlation equations are given for the local and average Nusselt numbers.