Viscous dissipation effects in mixed convection heat transfer in a porous square cavity

The present paper studied numerically the effect of viscous dissipation on the steady mixed convection in lid-driven cavity filled with porous medium. The left vertical wall of the cavity heated to a temperature (Th) while the right wall cooled to a temperature (Tc), the horizontal walls of cavity are kept adiabatic. A numerical program written in COMSOL Multiphysics software, was developed, to solve the Navier Stokes and energy equations, under the Darcy-Brinkman formulation. In order to investigate the viscous dissipation effect a comparison is made between four models. Moreover, the entropy generation and Nusselt number were studied as a function of Darcy number. The results show that the influence of the different viscous dissipation models on the entropy generation strongly depends on the Darcy number and can in some case reverse the heat transfer from the fluid to the heated wall.