Experimental and numerical analysis of the effect of the position of a bottom wall hot source on natural convection

An experimental and numerical analysis of natural convection in a square cavity with partially active thermal side walls and an additional active source located in the center of the bottom wall is investigated for Rayleigh numbers ranging from 104 to 10(5). The analysis was carried out experimentally through holographic interferometry and numerically using CFD software. Interferograms, streamlines, isotherms and velocity maps are analyzed for three different positions of the hot source. The square cavity of dimensionless height H is made of Plexiglas with four cold sources and a hot source. The sources are made of aluminum and their dimensionless height is H-s = 0.25. The hot source is placed on the bottom cavity wall and its dimensionless position varies from D = 0.4 (corresponds to the middle of the bottom of the cavity) to D = 0.6. The results clearly show that different positions of the hot source have an effect on heat transfer. Two vortices develop inside the cavity. In the symmetrical position, the vortices are independent of Rayleigh number while in the other two configurations the left vortex becomes larger than the right one. D = 0.4 is the best position of the hot source in order to create the fastest velocity field able to remove the heat generated in the cavity in the best way. (C) 2015 Elsevier Ltd. All rights reserved.