BUOYANCY DRIVEN FREE CONVECTION TURBULENT HEAT TRANSFER IN AN ENCLOSURE

Abstract

Equations governing natural convection have been solved using a fast and stable finite difference approximation, which has been developed and validated. The low–Reynolds number k − e model has been used in this case because of its high accuracy in turbulence flows.Turbulent flow in an enclosed cavity or box is a model for many flows of practical interest: cooling of electronic equipment; heating of a room; flow in a double glazing unit or ventilation, is encountered in a number of situations of practical importance in our every day encounters.A three-dimensional enclosure in form of a rectangular enclosure containing a convectional heater built into one wall and having a window in the same wall have been studied. The heater is located below the window and the other remaining walls are insulated. The size and position of the window and heater are fixed. The localized heating and cooling induces two boundary layers that collide in the region between the window and heater. The timed averaged equations for Continuity, Momentum and Energy, which are coupled to the Turbulence equations, were solved using a finite difference approximation (F.D.A) technique. The vorticity-vector potential formulation has been employed. A further use of difference false transient factors in different flow regions coupled with non-linear partial differential equations has been employed to fasten convergence of the numerical solution. The results were that the enclosure is stratified into three regions: a cold upper region, a hot region in the area between the heater and the window and a warm lower region..