A Relation Between Permeability and Size Distribution of Pores

Summary An equation has been derived for the relation between permeability and the size distribution of the pores in isotropic material. If the mean radius of the pores in each of n equal fractions of the total pore space is represented in decreasing order of size by r 1 , r 2 ., and rn cm. respectively, then permeability is given by image where is the porosity in cm. 3 /cm. 2 of porous material, and K is in units of cm. 2 By this means, permeability can be calculated from she curve relating water content to suction. This has been tested on published data for flow of air through porous stones and flow of water through saturated and unsaturated sands. Calculated values have been found to agree satisfactorily with measured values over a wide range of permeability. The Kozeny equation is discussed as a particular case of this equation