In this paper a new numerical method is presented for the analysis of combined natural convection and radiation heat transfer which has application in many engineering situations such as materials processing, combustion and fire research. Because of the recent interest in the performance of these engineering processes in the low-gravity environmental of space, attention is devoted to both 1-g and low-g applications. The numerical study is based on a two-dimensional mathematical model represented by a set of coupled nonlinear partial differential equations for conservation of mass, momentum, and energy and the integro-differential equations which describe radiative heat transfer. Radiative exchange is formulated using the discrete exchange factor method (DEF). This method considers point to point exchange and provides accurate results over a wide range of radiation parameters. The desirable features of DEF are briefly described. Our numerical results show that the radiation significantly influences the flow and heat transfer in the enclosure. In both low-g and 1-g applications, radiation modifies the temperature profiles and enhances the convective heat transfer at the cold wall. In a low-g environment, convection is weak and radiation can easily become the dominant heat transfer mode. It is also shown that in the top-heated enclosure, volumetric heating by radiation gives rise to an intricate cell pattern in the cavity.
Kassemi, M., Naraghi, M.H., Analysis of Radiation-Natural Convection Interactions in 1-G and Low-G Environments Using the Discrete Exchange Factor Method, AIAA/ASME Thermophysics and Heat Transfer, ASME, New York, NY, HTD-Vol. 137, pp. 189-197, June 18, 1990.