Wicking within forests of micropillars

We describe how a wetting liquid brought into contact with a forest of micropillars impregnates this forest. Both the driving and the viscous forces depend on the parameters of the texture (radius b and height h of the pillars, pitch p of the network) and it is found that two different limits characterize the dynamics of wicking. For small posts (hp), the speed of impregnation becomes independent of the pillar height, and becomes mainly fixed by the radius of the posts.