Capillary spreading of a droplet in the partially wetting regime using a diffuse-interface model

The spreading of a liquid droplet on a smooth solid surface in thepartially wetting regime is studied using a diffuse-interface model,based on the Cahn-Hilliard theory. Following \cite{Jac00} the modelis extended to include non-90$^{\circ}$ contact angles. Thediffuse-interface model applied considers the ambient fluid displacedby the droplet while spreading as a liquid. The governing equationsof the model for the axisymmetric case are solved numerically using afinite/spectral element method. The viscosity of the ambient fluid isfound to affect the time scale of spreading, but the general spreadingbehaviour remains unchanged. Wettability expressed in terms of theequilibrium contact angle is seen to influence the spreading kineticsfrom the early stages of spreading. The results showagreement with the experimental data reported in the literature.