
A three-dimensional study of steady laminar natural convection in partially top vented enclosure is investigated numerically. A discrete heat source mounted on the substrate at the bottom wall is used to simulate an electronic component. Three types of heat source are used with vent aspect ratio ranging from 0.0 to 0.1. The problem is described by continuity, momentum and energy partial differential equations, which are expressed in Cartesian coordinates system. The proposed governing equations are transformed to a set of dimensionless partial differential equations which, is solved with finite difference technique. A computer program is developed to solve the present proposed mathematical model. Solutions are obtained for Rayleigh number ranging from 1.0×104 to 1.0×106, enclosure aspect ratios ranging from 0.1 to 1.0 and Prandtl number 0f 0.7. The resulting flow and temperature patterns are discussed. Accordingly, the values of Nusselt number for different values of problem parameters are obtained. Comparisons between the present obtained results and the previous theoretical studies are performed for different values of problem parameters.