This study presents a numerical simulation of fluid flow and heat transfer due to natural convection within a square chamber (square cavity), fully filled with a yield stress fluid obeying the Bingham model of behavior. Two dimensional, steady state, laminar flow with differentially heated vertical walls (side walls) and insulated horizontal walls (top and bottom) have been considered. Plasticity effects on heat mass transfer are investigated for nominal values of Rayleigh number (Ra) in the range of  We have fixed the Prandtl number  and Bingham number  to mimic a real incompressible plastic fluid. It is found that the average Nusselt number  increases with the increasing of Rayleigh number for the both cases Newtonian and non-Newtonian fluids. However, for the same value of Rayleigh number, the average Nusselt number of Bingham fluid presents a diminution comparing with the Newtonian fluid, due to yield stress effects on the convective term.

natural convection, numerical simulation, laminar flow, square cavity, Bingham fluid, heat and mass transfer, Nusselt number.