Improved estimate of the effective diameter for use in the Kozeny–Carman equation for permeability prediction

Abstract

The Kozeny–Carman equation is widely used to predict the hydraulic conductivity or intrinsic permeability of granular porous media. This paper combines discrete-element modelling and finite-volume flow simulation to examine the Kozeny–Carman equation for permeability prediction of spherical grains with different grain size distributions. A comparison of the modelled permeability with the permeability predicted by the Kozeny–Carman equation shows that the existing equation predicts up to 20% smaller permeability for particle assemblies with non-uniform sizes, especially for gap-graded size distributions. An improved equation is proposed to calculate the effective diameter for use in the empirical Kozeny–Carman equation.