The Channel Network Model—A Tool for Transport Simulations in Fractured Media

Abstract

AbstractThe Channel Network model and its computer implementation, the code CHAN3D, are presented for simulations of fluid flow and transport of solutes. The tool may be used to simulate and interpret field experiments of flow and transport on a large or small scale. It also may also be used for performance and safety assessments of repositories for nuclear and other hazardous wastes, e.g., chemical wastes. From observations in the field it is deduced that the flow and transport take place in a three‐dimensional network of connected channels. The channels have different properties and are generated in the model from observed stochastic distributions. This allows us to represent the large heterogeneity of the flow distribution commonly observed in the field. Solute transport is modeled considering advection and rock interactions such as matrix diffusion and sorption within the interior of the rock. For repository conditions the main contributions to the dispersion of solutes come from the large variation in the flow field (channeling) and the rock interactions. Objects such as fracture zones, tunnels, and release sources can be incorporated in the model. In addition, a methodology of how data may be obtained for the model is described. Data may be obtained from borehole and laboratory measurements.