Simple hydrodynamic model of fast-mode kinetics in surface-mediated fluid phase separation

We propose here a simple physical model of the fast surface domain growth with the t3/2 algebraic law observed for surface-mediated phase separation of symmetric fluid mixtures. This unusually fast coarsening is likely caused by the hydrodynamic spreading of a more wettable fluid phase on a two-dimensional solid surface via bicontinuous fluid tubes. The gradual change in the growth exponent from 1 to 3/2 with an increase in the quench depth can likely be explained by the shape transition of wetting droplets from hemisphere to disk, which is induced by the increase in the wetting power with the quench depth. We also discuss the slowing down of the fast growth mode in the late stage. This slowing down is likely caused by the constraint that domain growth velocity cannot exceed the viscous-dissipation-limit velocity. {} 1996 The American Physical Society.