Dynamics of surface waves in wetting films

Acoustically excited linear waves in wetting films are described theoretica lly and their dispersion relation is derived. The analysis is based on the Reynolds lubrication theory, assuming interfacial mobility on the two film surfaces. The final result accounts for both the Marangoni effect on the li quid/gas surface and the slippage on the solid/liquid interface. New phenom ena are pointed which are related to the thickness dependence of the surfac e tension and the adsorption dependence of the disjoining pressure. It is s hown that these effects are important for the wave dynamics, and can even l ead to film instability. (C) 1998 Elsevier Science B.V. All rights reserved .