Abstract: A numerical study is carried out to investigate the interaction between mixed convection and thermal radiation in a horizontal ventilated enclosure. Air, a radiatively transparent medium, is admitted into the cavity by injection or suction, by means of two openings placed on the lower part of both right and left vertical sides. Another opening is located on the middle of the top wall to ensure the ventilation. The parameters governing the problem are the Reynolds number, Re, and the emissivity of the walls, ε. The effect of these parameters on flow and thermal fields as well as on the heat transfer rate within the enclosure is examined for the two ventilation modes (injection and suction). Variations, versus the main controlling parameters, of maximum and mean temperatures are also presented. The results indicate, for the two modes of imposed flow, that the thermal radiation affects the flow and thermal structures. Also, it is found that the radiation enhances the global heat transfer so that its contribution is more considerable even for the high values of Re. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.

Key words: Surface radiation, Mixed convection, numerical study, vented cavity, injection, suction