Combined Natural Convection–Conduction and Radiation Heat Transfer in a Discretely Heated Open Cavity

Abstract

Combined natural convection, conduction, and radiation heat transfer in an open-top upright cavity containing a discrete heat source has been modeled numerically. The surface emissivity has been varied and its effects on the flow and thermal fields have been determined for different values of Rayleigh number. The complex interaction of the three modes of heat transfer mechanisms is explored by solving the coupled convection, conduction, and radiation equations. It is noted that the inclusion of radiation has a significant effect on the flow, resulting in the formation of a recirculation zone within the cavity. Comparison of the local heat transfer coefficients for the conjugate analysis and no radiation case reveals that the inclusion of radiation has a negligible effect on the heat transfer performance of the heat source. However, comparison of the numerical results with experimental observations shows that accurate prediction of the flow and thermal fields is strongly dependent on the consideration of radiation heat transfer in the numerical case.