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

Abstract

A numerical study has been per- formed on mixed convection inside an open cav- ity 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 chan- nel are adiabatic. Three different cases are con- sidered by applying uniform heat flux on (a) the inflow side (assisting forced flow); (b) the out- flow side (opposing forced flow); (c) the bot- tom horizontal surface (transverse flow). The Galerkin weighted residual method of finite ele- ment formulation is used to discretize the govern- ing equations. For mixed convection, the influ- ential 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 temper- ature 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.