Homogenization of contact line dynamics

This paper considers the effects of substrate inhomogeneity on the motion of the three phase contact line. The model employed assumes the slowness of the contact line in comparison to capillary relaxation. The homogenization of this free boundary problem with a spatially periodic velocity law is considered. Formal multiple scales analysis yields a local, periodic problem whose time-averaged dynamics corresponds to the homogenized front velocity. A rigorous understanding of the long time dynamics is developed using comparison techniques. Computations employing boundary integral equations are used to illustrate the consequences of the analysis. Advancing and receding contact angles, pinning and anisotropic motion can be predicted within this framework.