title: Simultaneous thermal and surfactant-induced Marangoni effects in thin liquid films.
abstract: The deformation of a thin liquid film in the presence of a surfactant monolayer, varying temperature distributions, and limited mass flux is considered. Use of lubrication theory yields a coupled pair of partial differential equations for the film height and surfactant surface monolayer concentration. The long-wave stability of the isothermal film is examined over a wide range of parameter values. It is shown that droplet patterns are obtained under certain thermal conditions for both an isothermal and nonisothermal underlying substrate. For the case of a localized thermal gradient initially imposed at the air-liquid interface, severe film thinning beneath the heat source was observed, which was not accompanied by droplet formation; pseudo steady states are observed in this case. In all situations the surfactant is found to rigidify the air-liquid interface, retarding thermally driven flow, while evaporation (condensation) acts to destabilize (stabilize) the film.
authors.affiliation: Department of Chemical Engineering and Chemical Technology, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: B D
authors.initials: BD
authors.lastname: Edmonstone
authors.forename: O K
authors.initials: OK
authors.lastname: Matar