Effect of liquid films on the isothermal drying of porous media.

We study the effects of liquid films on the isothermal drying of porous media. They are important for the transport of liquid to an evaporation interface, far from the receding liquid clusters. Through a transformation, the drying problem is mapped to the Laplace equation around the percolation liquid clusters. From its solution, the properties of drying are obtained in terms of the capillary number. Consistent with experimental evidence, film flow is shown to accelerate drying significantly.