Macroscopic Description of the Forced Convection Process in Porous Media Flows

Abstract

As in the clear flow case, the forced convection process in porous media flows can be characterized by a thermally developing region and a fully developed region. In this study, microscopic laminar flow simulations are carried out in a bi-dimensional porous medium to study the characteristics of each region. For the two porosities simulated, 65% and 85%, the spatial variation of the macroscopic heat transfer coefficient and the streamwise thermal dispersion is computed for different Pe numbers. The dependence of the thermal entry length on the Pe number is also computed. This quantity is found to be larger than five Representative Elementary Volumes for Pe numbers larger than 2500. This shows that, for high Pe numbers, the thermal entrance effect is not limited to the pore-scale and that macroscopic models used in the open literature are only accurate in the fully developed region.