Natural, Forced and Mixed Convective Flows in a Square Ventilated Cavity

Abstract

The combined forced and free convection heat transfer and the fluid flow parameters within a square vented cavity were analyzed numerically. The bottom wall was heated by spatially changing the temperature, while the other three walls remain cold. The purpose of this research is to demonstrate how natural convection effects may improve forced convection inside a square cavity. The governing equations were discretized using the finite volume technique in curvilinear coordinates with staggered variables. The present research used a two- and three-step time-splitting technique for the energy and momentum equations, respectively. The Richardson number (Ri) was computed in the range (0.1) to (30), the Reynolds number (Re) was computed in the range (10) to (500), and a fixed Prandtl number was computed (0.71). The associated flow and heat field within the square cavity were represented using a streamline, velocity vector, and isothermal contour. The findings shown that the increase of heat transfer rate is highly dependent on the Richardson number parameters. Richardson number determines the number of big vortices (recirculating flow). It will consist of one at Ri 5, two at Ri 15, and three at Ri 30 with tiny bubbles (minor vortices) growing near the cavity's top and/or lower walls. The behavior of streamlines, isotherms, horizontal and vertical velocity distributions, and the time-dependent variation of the average Nusselt number will be totally different under the three heat transfer regimes of forced, natural, and mixed convection.