Theoretical Analysis of Natural Convection in an Enclosure Filled with Disconnected Conducting Square Solid Blocks

Two different approaches have been implemented to interpret the existing data in Merrikh and Lage (2005a, in: Pop, Ingham, Transport Phenomena in Porous Media, Elsevier, Oxford) pertinent to the pore-scale simulation of natural convection in a laterally heated square enclosure filled with a fluid bathing discrete, disconnected and conducting solid blocks. Mathematical analysis of the problem based on the least squares method leads us to a Nu-Ra correlation with the solid-to-fluid thermal conductivity ratio and the porous medium permeability as the controlling parameters. In this study, while the porosity is fixed, the permeability is varied by changing either the block size or the number of blocks. Hence, three independent variables N, Ra, and κ being the number of blocks, Rayleigh number, and the conductivity ratio between the solid and the fluid, respectively, affect the overall heat transfer process. Based on a simplified thermal resistance approach, an alternative correlation is proposed to predict the Nusselt number as a function of the aforementioned parameters. Detailed analysis of the results and the expected errors are presented.