Effect of double stratification on free convection in a darcian porous medium

The problem of free convection heat and mass transfer from vertical surface embedded in a doubly stratified porous medium has been studied. The similarity solution is presented for the case of uniform heat and mass,flux conditions when the thermal and solutal stratification of the medium arc assumed to have the power function form x(1/3). The flow, temperature and concentration fields are effected by the complex interactions among the diffusion ratio parameter Le and buoyancy ratio parameter N in addition to the flow driving Darcy-Rayleigh number Ra-x. The temperature and concentration profiles are effected due to double stratification of the medium and its effect on the Nusselt and Sherwood numbers is discussed.