A NEW COUPLING TERM FOR DUAL-POROSITY MODELS

Numerous models are available for simulating dual‐porosity flow of groundwater, heat, or solute in a fractured porous medium. Each approach includes various approximations and results in models of varying complexity. One of the simplest models has been proposed by both Barenblatt et al. (1960) and Warren and Root (1963). It assumes that the flow exchange (of fluid, heat, or solute) between the two porosity systems can be written as a linear function of the difference between averaged driving potentials (pressure, temperature, or concentration). This has been called a quasi‐static formulation because it can be shown to be correct only for long dimensionless time. A new formulation of this model is proposed here which retains the original simplicity but is not restricted to very slow transient flows. The integral method is used to derive the coupling term for the early parts of the transient regime. This paper is not subject to U.S. copyright. Published in 1990 by the American Geophysical Union.