A numerical investigation was conducted to study the enhancement of heat transfer in a cavity with heated rectangular blocks and submitted to a vertical jet of fresh air from below. The heated blocks are identical, and the system presents a symmetry with respect to a vertical axis passing through the middle of the opening. The cavity resembles a cooling passage of electronic equipment. The governing equations are solved by using the finite difference method. This study was conducted with the control parameters as: Ra = 10(5), 10(6); 1 less than or equal to Re less than or equal to 1000; C = 0.15 and 0.25 less than or equal to D less than or equal to 0.75. The relative height of the blocks and the geometric parameter of the cavity are kept constant (B = 1/2 and A = 1). The results obtained, with Pr = 0.72, show the validity of multiple solutions on which the resulting heat transfer depends. Some useful correlations are then proposed. (C) 2003 Elsevier Ltd. All rights reserved.