MODELING OF COMBINED RADIATIVE AND CONVECTIVE HEAT TRANSFER IN AN ENCLOSURE WITH A HEAT-GENERATING CONDUCTING BODY

In this paper, we present a numerical study of the radiation-natural convection interactions in a differentially heated enclosure, within which a centered, squared, heat-conducting body generates heat. A specifically developed numerical model based on the finite-volume method and the SIMPLER algorithm is used for the solution of the governing equations. The working fluid (air) is perfectly transparent to the radiation. The Rayleigh number Ra and the temperature-difference ratio Delta T* were varied parametrically. For Pr = 0.71, the results obtained show that: (i) The isotherms and streamlines are strongly affected by the radiation exchange at high Rayleigh numbers (Ra >= 10(6)), (ii) the temperature of the inner body decreases under the radiation exchange effect, (iii) for a constant Ra, the average Nusselt number at the hot and cold walls (Nu(h) and Nu(c)) vary linearly with increasing Delta T*: Nu(h) decreases with Delta T* while Nu(c) increases with Delta T*. Furthermore, the radiation exchange increases both average Nusselt numbers Nu(h) and Nu(c), especially at Ra >= 10(5), and consequently, Delta T(o)* increases.