Modelling the effect of capillary pressure on a liquid flow in a porous medium

Abstract When the free surface of liquid flowing downward through a porous medium comes into the medium, the liquid flow is made difficult due to a capillary pressure that arises at the meniscus. Practically, such a capillary pressure should become important when the top surface of a riser in ingots and castings solidifies to form a mushy zone, because it makes the feeding of liquid to compensate for solidification shrinkage difficult. A model is put forward to evaluate the effect of the capillary pressure on the liquid flow in a porous medium. Using the model, the apparent permeability of the medium is predicted and is compared with experimental results presented in the previous paper.