A simple, explicit model for the transverse permeability of porous media comprised of alternating layers of tows of varying permeability has been proposed. The development of the model is based on results of numerical simulations as well as an earlier developed analytical model for the permeability of such systems (Markicevic and Papathanasiou, 2003). Based on the above, as well as on physical arguments regarding the flow across such dual porosity media, we formulate an explicit model in terms of dimensionless permeabilities. Extensive validation of the model is carried out through numerical simulations using the CFD package FIDAP. A good agreement between the permeabilities predicted by the simple explicit model and those calculated numerically is found. From this model, the form of a master curve for the permeability of such system has been deduced.