Computational Fluid Dynamics as a Tool to Estimate Hydraulic Conductivity of Permeable Asphalts

Hydraulic conductivity (k) is critical for designing permeable pavements for safety and environmental reasons. A novel approach for estimating k is through computational fluid dynamics (CFD) applied to permeable asphalt (PA). Specimens of PA are examined in this study to evaluate CFD applicability. Tortuosity, effective porosity, pore size distribution, and specific surface area were determined based on three-dimensional specimen structures reconstructed using x-ray tomography analyses. Using CFD, estimates of k were determined and compared with physical measurements and also with the results obtained from the semi-empirical modified Kozeny-Carman model (KCM). The comparison shows that the numerical simulations with CFD can be a reasonable tool for estimating k and for examining transport of water through PA. Within the constraints of this study, results infer that CFD can provide more representative results for low k in comparison with KCM. For higher k, CFD and KCM results were reasonably comparable.