Suitability evaluation of an equivalent porous medium method for characterizing 2-D flow based on the fracture fractal dimension

Abstract

ABSTRACT An equivalent porous medium (EPM) method is widely utilized in various practical applications of hydrogeological engineering with areas of a fractured geological medium (FGM). However, the suitability of the EPM model still lacks sufficient scientific evaluation when considering the distribution of water head and flow velocity. In this study, the suitability of the EPM model to the fractal dimension of a discrete fracture network (DFN) is analyzed based on numerical simulation experiments. The simulation results of the EPM model are compared with those of the DFN model. Then, a formula is proposed to evaluate the suitability of the EPM model for characterizing two-dimensional flow distribution. The results show that with the increase of the fractal dimension, the suitability of the EPM model decreases first and then increases, and the inflection point gradually appears in advance with the increase of the length–width ratio of the simulation domain. The length–width ratio of the simulation domain has a linear relationship with the suitability of the EPM model, and the slope increases with the increase of the fractal dimension. Finally, a quantitative evaluation method is proposed to calculate the suitability of the EPM model based on the fractal dimension and the length–width ratio of the simulation domain.