DOUBLE DIFFUSIVE CONVECTION IN A POROUS CAVITY NEAR ITS DENSITY MAXIMUM

Natural convection of cold water around its density maximum in two-dimensional cavity filled with a water-saturated isotropic porous medium is studied numerically. The horizontal walls of the cavity are insulated. The opposing vertical walls are kept at different temperatures theta(h) and theta(c) (theta(h) > theta(c)). The concentration levels at the cold wall and the hot wall are respectively C-c and C-h with C-h > C-c. The governing equations are solved by the finite volume method using the SIMPLE (semi-implicit method for pressure linked equation) algorithm with the QUICK scheme of Hayase et al. The results are presented in the form of streamlines, isotherms, isoconcentrations and mid-height velocity profiles for various values of thermal Rayleigh number, density inversion parameter, buoyancy ratio, Schmidt number, Darcy number and porosity. In addition, results for the average Nusselt number and Sherwood number are presented and discussed for various parametric conditions. It is observed that the Nusselt number and the average Sherwood number behave nonlinearly with increasing buoyancy ratio number.