Three dimensional numerical study of natural convective heat transfer of liquid for two heaters installed in a cubic enclosure

Steady-state laminar natural convection in a cubic enclosure with a cold vertical wall and two hot square heaters on the opposite wall is studied numerically. The enclosure is filled with various liquids. Three-dimensional form of Navier-Stokes equations are solved by employing SIMPLE algorithm. Computations are performed for a range of Rayleigh number from 10 ³ to 10 ⁷ while enclosure aspect ratio varies from 0.05 to 1.6. The effects of Rayleigh number, enclosure aspect ratio and Prandtl number on heat transfer characteristics are studied in detail. The results show that the flow field is very complex and heat transfer from the heaters is not uniform. The effects of Prandtl number are negligible in the range from 5 to 140 with other parameters keeping constant. This allows the use of liquids such as water for studying other dielectric liquids provided the flow geometry and other non-dimensional parameters are similar. The overall Nusselt number increases with Rayleigh number markedly. It also is affected by enclosure aspect ratio. It attains the maximum value when aspect ratio is in the range of 0.05-0.3 and decreases as enclosure aspect ratio varies from 0.3 to 1.6. Also various settings of cooling face and arrangement of heaters are studied, the results showing that these have considerable effects on heat transfer of both heaters.