Abstract:

 The coalescence process between two small liquid drops in surfactant solutions has been studied. A model is developed for the dynamics of the thinning dimpled film in which the influence of London-van der Waals forces is considered. The effects of surface diffusion, interfacial viscosities, and interfacial tension gradient on coalescence are investigated. The coalescence time, which is the time required for the thinning and rupture of the liquid film, is expressed as a function of the drop sizes, the physical properties of two liquid phases, and inter facial properties. The predictions are in good agreement with the previous experimental data.

Key words: Liquid drop, Coalescence time, Liquid film flow