MEASUREMENT OF VOID SIZE CORRELATION IN INHOMOGENEOUS POROUS-MEDIA

In previous works, we have described a void space reconstruction metho d based on non-wetting fluid intrusion, wetting fluid drainage, and im age analysis data. The method has been applied to a wide range of subs tances, including sandstone, compressed and sintered powders, paper su bstrates and coatings, soil and fibrous mats. We have also demonstrate d in a previous work that the spatial correlation of similarly sized v oids within inhomogeneous porous media has a huge effect on permeabili ty. We therefore describe a method of measuring such correlation, suit able for use in our void space reconstructions. The method involves a cubic spline smoothing of a variogram of the void sizes in a binary im age of the porous medium. It has been successfully tested on an artifi cially correlated void network, comprising two sintered glass discs of different Void size ranges. Stereological effects, caused by the off- centre sectioning of voids, can interfere with the variogram features. Our method is shown to be insensitive to artificially generated stere ological interference. The method is also applied to sandstone samples .