Abstract：An equivalent pore network model (EPNM) describes complex pore structures in a porous media by statistical parameters. Previous studies using such models have focused on seepage and mechanical dispersion, with few studies considering the effect of molecular diffusion on solute transport. In this study, the convection, molecular diffusion and mechanical dispersion of solutes in porous media were studied using an EPNM to predict the solute transport in porous media. A sensitivity analysis of the model parameters was used to study the effect of the pore structure characteristics on the effective diffusion coefficient of the porous media. The influence of molecular diffusion on the hydrodynamic dispersion was analyzed by comparing numerical results with and without molecular diffusion. The results show that the effective diffusion coefficient, which negatively correlates with the throat curvature and positively correlates with the coordinate number and the connection number ratio, is affected by both the pore volume and the pore-throat diffusion capacity. The molecular diffusion correlates with the convection-induced mechanical dispersion to accelerate the solute transport in the low-velocity region. The results of this study show the microscopic mechanisms influencing molecular diffusion for hydrodynamic dispersion as a theoretical basis for predicting the solute transport flux in pore network models.
张兴昊, 林丹彤, 胡黎明. 基于等效孔隙网络模型的水动力弥散数值模拟[J]. 清华大学学报（自然科学版）, 2022, 62(12): 1906-1914.
ZHANG Xinghao, LIN Dantong, HU Liming. Numerical simulations of hydrodynamic dispersion based on an equivalent pore network model. Journal of Tsinghua University(Science and Technology), 2022, 62(12): 1906-1914.
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2022, Vol. 62 
