Simulations of Rupture in Thin Films of Evaporating Liquids

Abstract

Evolution of dry patches in a thin film of a volatile liquid on a uniformly heated plate is investigated in the framework of a lubrication-type model. The effects of surface tension, evaporation, thermocapillarity, and disjoining pressure are taken into account. Dry areas on the plate are modeled by isothermal microscopic films, which are in thermodynamic equilibrium with the vapor. For non-polar liquids such equilibrium is achieved due to van der Waals forces. Simulations indicate formation of a well-defined capillary ridge around a growing dry patch and show increase in the contact line speed with time. For polar liquids the microscopic film is formed by combined action of van der Waals and electrical double layer forces, the capillary ridge is very small and the contact line speed quickly approaches a constant value. Numerical simulations demonstrate that the proposed model is capable of describing a number of complicated phenomena observed in dewetting of evaporating films.