Internal flow mechanism in filter cakes

The definition of filtration resistance is modified by considering relative solid‐liquid velocity. The internal flow mechanism in a filter cake is reexamined in view of the movement of solids during compression. Under conditions of short filtrations involving highly concentrated slurries, the velocity of solids is shown to be comparable to the velocity of the liquid. A differential equation is proposed for the flow through compressible cakes in which the pressure gradient is assumed proportional to the difference in average velocities of the liquid and solid rather than to the average velocity of the liquid alone. An improved definition of the average filtration resistance is developed on the basis of the new flow equation.