Numerical Study on Gas Diffusion in Partially Connected Porous Media reconstructed by Hierarchical Simulated Annealing Approach

In this work, gas diffusion through partially connected porous media (PCPM) is numerically studied through combination of CFD modeling and simulated annealing. To be specific, PCPM are first characterized by statistical morphological descriptors (SMDs) based on the entire and interconnected pore space, respectively. Two hierarchical simulated annealing (HSA) algorithms based on these two set of descriptors are developed to obtain the corresponding digital reconstructions. Using the pore-scale modeling and appropriate averaging, the effective diffusivity of gas diffusion through these PCPM are calculated. Interestingly, it is found that the effective diffusivity at REV-scale is well approximated by the constructed PCPM based on the entire pore space; whereas those based on the interconnected pore space underestimate its values. The results reveal the complicated dependence of the effective diffusivity on the underlying pore structure