Numerical studies of solute transport in a fractured medium subject to near- and non-equilibrium mass transfer

Numerical investigations of solute transport in a fractured medium consisting of a plane fracture surrounded by a rock matrix are conducted. The transport in the liquids is described by advection-diffusion equations, while the boundary interactions within the rock matrix are modeled by use of isotherms. Near-equilibrium and non-equilibrium conditions are considered, and computations are carried out for a wide range of rock matrix and interaction parameters. We find that if the solute travel time is much greater than the time constant governing the rate of adsorption-desorption occurring in the rock matrix, nearequilibrium conditions may be assumed. However, if the travel time is comparable to the time constant, then the non-equilibrium considerations are important