Permeability prediction of isotropic fibrous porous media

Fibrous porous media find application in several industrial engineering disciplines including filtration processes and fuel cells. In the present study a geometric pore-scale model is introduced and used to predict the permeability of isotropic fibrous porous media. The model is based on a unit cell approach in which the fibres of the actual porous medium are modelled based on rectangular geometry. At first the model is used to predict the permeability of cross-flow through an array of unidirectional fibres. The permeability is expressed as a function of the solid volume fraction and a pore-scale linear dimension. In addition a three-dimensional isotropic model is proposed by performing a weighted average on the model for cross-flow and a model from the literature for flow parallel to the fibre axes. The resulting model is compared to a comprehensive collection of experimental data from numerous authors, based on various types of fibrous porous media, including that of entangled polymer networks. The Kozeny ``constant'' is calculated for different solid volume fractions and it is illustrated that the pore-scale model introduced conserves the constancy of the Kozeny constant.