Droplet motion on chemically heterogeneous substrates with mass transfer. II. Three-dimensional dynamics

We consider a thin droplet that spreads over a flat, horizontal and chemically heterogeneous surface. The droplet is subjected to changes in its volume though a prescribed, arbitrary spatiotemporal function, which varies slowly and vanishes along the contact line. A matched asymptotics analysis is undertaken to derive a set of evolution equations for the Fourier harmonics of nearly circular contact lines, which is applicable in the long-wave limit of the Stokes equations with slip. Numerical experiments highlight the generally excellent agreement between the long-wave model and the derived equations, demonstrating that these are able to capture many of the features which characterize the intricate interplay between substrate heterogeneities and mass transfer on droplet motion.