NUMERICAL STUDY OF NATURAL-CONVECTION FROM A VERTICAL SURFACE DUE TO COMBINED BUOYANCIES

The phenomenon of natural convection mused by combined heat and mass transfer from a vertical surface situated in a binary mixture is numerically studied. A control volume based finite element method with vorticity-stream function formulation is used (as a test method) to solve the transport equations. Excellent consistency is obtained between the results available in the literature and the present numerical solutions. A range of values is considered for thermal Grashof number, buoyancy and concentration ratios, and Prandtl and Schmidt numbers. Both aiding and opposing flows are investigated The results indicate that for a concentration ratio Cr >> 1, the average Nusselt and Sherwood numbers at the vertical surface are independent of Cr; and the complex trends of the transport are profoundly influenced by the buoyancy ratio and the Prandtl and Schmidt numbers. The applicability of Ackermann's classical theory is pointed out, and comprehensive results of the average Nusselt and Sherwood numbers are presented.