Mixed Convection Heat Transfer Enhancement in a Vented Cavity Filled with a Nanofluid

In this paper, a numerical investigation is carried out on mixed convection in a vertical vented rectangular enclosure filled with Al۲O۳-water nanofluid. The mixed convection effect is attained by heating the right wall by a constant hot temperature and cooling the cavity by an injected or sucked imposed flow. The effects of some pertinent parameters such as the Reynolds number, ۱۰۰  Re  ۵۰۰۰, the solid volume fraction of the nanoparticles, ۰    ۰.۱, and the aspect ratio of the cavity, ۱  A  ۴, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes. For a value of the aspect ratio A = ۲, the obtained results demonstrate that the increase of volume fraction of nanoparticles contributes to an enhancement of the heat transfer and to an increase of the mean temperature within the cavity. Also, it was revealed that the fluid suction mode yields the best heat transfer performance. In the case when A is varied from ۱ to ۴, it was obtained that the heat transfer enhancement, using nanofluids, is more pronounced at shallow enclosures than at tall ones.