Lucas-Washburn kinetics for capillary penetration between periodically corrugated plates

Capillary rise of a liquid between two sinusoidally corrugated plates in a gravitational field is examined in order to study the effect of structural variations perpendicular to the direction of penetration on the rate of capillary penetration. A simplified approach, using the assumptions of the Lucas-Washburn model (1, 2) for kinetics of capillary rise in an isolated cylindrical capillary, is used to calculate the rate of penetration of a liquid from an infinite reservoir into the capillary. It is found that the penetration rate is strongly dependent on the geometrical parameters. Increasing the amplitude of corrugation leads to a significant increase in the time necessary to achieve the equilibrium rise height even though the "effective" capillary gap width remains unchanged. These results emphasize the significance of microstructural information in determining capillary penetration behavior of porous materials.