Two Dimensional Numerical Simulation of Mixed Convection in a Rectangular Open Enclosure

A numerical study has been performed on mixed convection inside an open cavity on the bottom of a channel. One of the three walls of the cavity experiences a uniform heat flux while the other walls and the top of the channel are adiabatic. Three different cases are considered by applying uniform heat flux on (a) the inflow side (assisting forced flow); (b) the outflow side (opposing forced flow); (c) the bottom horizontal surface (transverse flow). The Galerkin weighted residual method of finite element formulation is used to discretize the governing equations. For mixed convection, the influential parameters are the Grashof number (Gr), Richardson number (Ri) and Reynolds number (Re) by which different fluid and heat transfer characteristics inside the cavity are obtained. In the present study, velocity vectors, streamlines, isotherms, non-dimensional vertical velocities, maximum non-dimensional heated wall temperature and average Nusselt number of the heated wall are reported for Ri = 0.1 to 100, Re = 100 and the ratio of channel and cavity heights (H/D) with the range of 0.1 to 1.5. With the increase of Richardson numbers, the convective heat transfer becomes predominant over the conduction heat transfer. From the computation, it is observed that the higher heat transfer occurs for opposing forced flow situation at low Richardson number. For higher Richardson number, a better thermal performance is achieved for the transverse flow case.