NON-ERGODIC EFFECTS ON SOLUTE TRANSPORT IN RANDOMLY HETEROGENOUS POROUS MEDIA

摘要

Solute transport in randomly heterogeneous porous media is a complicated process. When the source area of a plume is small, it induces an uncertainty on the ensemble average of the plume center of mass in the movement of contaminant. This phenomenon is referred to non-ergodic transport. The nonergodic transport in two dimensions is investigated in this study. The results show that the nonergodic effect prolongs the whole transport process and leads to a smaller asymptotic longitudinal macrodispersion coefficient and a lower peak transverse macrodispersion coefficient than does the ergodic condition. The configuration of the source area affects the macrodispersion coefficient significantly. When the elongation of source area is parallel to the mean flow direction, the longitudinal macrodispersion coefficient reaches a smaller value than that from the ergodic condition. Further, anomalous negative transverse macrodispersion coefficients may appear. If the elongation of source area is perpendicular to the mean flow direction, the non-ergodic effect mitigates when the source area is enlarged. The model effects caused by different correlation functions of hydraulic conductivity on non-ergodic transport are found to be less significant than the non-ergodic effect.