Enhanced Three-Dimensional Mixed Convection in a Horizontal Channel Using a Baffle

Abstract

Three-dimensional mixed convection inside a horizontal rectangular channel with a square heated surface on one of the vertical sidewalls and an infinitely thin baffle installed on the opposite insulated sidewall is numerically investigated. Attention is focused on the influence of the baffle position (−2 to 2), the inclination angle between the baffle and the horizontal (15° to 90°), and the baffle height (0.2 to 0.9) on the flow and thermal characteristics. The other parameters remain unchanged: the Reynolds number (100), Grashof number (50,000) and Prandtl number (0.71). The results show recirculation around the top portion of the heated surface due to strong buoyancy. The heat transfer depends strongly on the relative positions of the baffle and the recirculation. Heat transfer enhancement is obtained with a higher baffle and a larger inclination angle if the baffle is close to the cold main stream. In contrast, the average Nusselt number is slightly smaller if the baffle is surrounded by the recirculation than it is without the baffle. An accurate correlation is proposed for calculating the average Nusselt number over the investigated range of the baffle position and the inclination angle for a fixed baffle height (0.75).