Numerical Investigations for Flow and Transport in a Rough Fracture with a Hydromechanical Effect

Abstract

The flow and transport properties in a rough fracture under effective normal stress conditions are investigated numerically. In this study, a rough fracture is represented by a field of variable apertures spatially correlated by using the non-conditional geostatistical method. In order to represent a nonlinear relationship between the effective normal stress and the fracture aperture, a simple mechanical model is combined with the local flow model. The solute transport is simulated by using the random walk particle following the algorithm. Numerical results show that the fluid flow and solute transport are significantly affected by the geometry of aperture distribution, which is varied with applied effective normal stresses and by the spatial correlation length ratio, which is defined as the ratio of lag distance (λ) to fracture length (L). The most efficient flow path is different with increasing effective normal stress, but maintains almost the same form at its higher values. In addition, solute particles displace only along channels reduced by contact areas increasing with the effective normal stress, and their spatial dispersion thus becomes constant.