Effect of porous inserts on turbulent heat transport past an abrupt expansion in a channel

Resumo

This paper presents numerical results for turbulent heat transfer in channels presenting a sudden expansion and obstructed by a porous layer. The turbulence model of Pedras and de Lemos (2001) is further developed to consider heat transfer analysis. The concept of double decomposition introduced by Pedras and de Lemos (2000) is extended to the energy equation and a set of macroscopic transport equations for flow and heat transfer analysis is proposed. Within the porous inserts, additional terms are considered for the turbulence kinetic energy equation and its dissipation rate. Governing equations for the mean and turbulent fields are written in their high Reynolds form and are discretized by means of the control volume method. Wall proximity is treated with the wall function approach and the algebraic equation set is relaxed with the SIMPLE method. Solution is sought for both the clear fluid region and the porous material in a unique computational domain. The effects of thickness and permeability of the inserts on flow pattern and heat transfer features are assessed. It is found that for some combinations of thickness and permeability, the recirculating bubble right after the step is completely suppressed, improving the heat transfer characteristics for the lower wall. © 2002 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.