Numerical simulation of buoyant, turbulent flow. I - Free convection along a heated, vertical, flat plate. II - Free and mixed convection in a heated cavity

Numerical models are presented to predict free and mixed convection low Reynolds number turbulent flows. A k-epsilon model and an algebraic stress model are used for the case of free convection along a heated vertical flat plate. Both models are found to yield accurate results for the mean flow and heat transfer, and measurements compare well with previous predictions. In the second part, the simpler k-epsilon formulation, based on the notion of eddy diffusivities for momentum and heat, is extended to predict steady free and mixed flows of air in a strongly heated cavity of arbitrary cross-section and orientation. Numerical calculations indicate that free convection flow is governed by the cavity aspect ratio, inclination angle, and Grashof number. As the relative ratio of inertia to buoyant forces is increased, the details of mixed convection flow are seen to become asymptotically independent of alpha, and as it approaches 1, a Nusselt number miminum is found.