Threshold pressure in capillaries with polygonal cross section

An analytical expression for the threshold pressure of capillaries with irr egular polygonal cross section is obtained using the MS-P method. The cases of a regular polygonal, an arbitrary triangular, and a rectangular cross s ection are obtained as particular cases of the general expression. Some reg ularities of the threshold pressure with the shape factor and the wetting p hase saturation for different capillary geometries are reported. The derive d expressions are valid for any value of the contact angle and can be used directly in a pore network simulator. (C) 2001 Academic Press.