ON THE NATURAL-CONVECTION IN A CAVITY WITH A COOLED TOP WALL AND MULTIPLE PROTRUDING HEATERS

Natural convection in rectangular enclosures with multiple protruding heaters mounted on one side wall is of-relevance to the cooling of ele ctronic equipment. In some configurations, the top wall behaves as the hear sink while the opposing vertical wall and the bottom wall are in sulated. The present work examines the peculiarities introduced in the natural convection process for such configurations. The enclosure con sidered had five protrusions, cavity width to heater length ratio of 1 .2 and cavity height to heater length ratio of 11. It is shown that fo r such configurations, a stable flow exists only at lower Rayleigh num bers and that above a certain critical Rayleigh number, only quasi-ste ady solutions exist. At low Rayleigh numbers (Ra less than or equal t o 1.5 x 10(7)), the flow is stable and characterized by the presence o f a primary flow cell and a counter-rotating secondary cell at the top of the enclosure. At higher Rayleigh numbers (Ra greater than or equ al to 3 x 10(8)), however, the isothermal top wall causes a periodic f low pattern to develop within the enclosure. Several interesting chara cteristics of the flow and temperature fields are presented. Results c ompared with previous experimental and numerical work are found to be in good agreement.