Fluid-dynamical model for antisurfactants

Conn, Justin J. A. and Duffy, Brian R. and Pritchard, David and Wilson, Stephen K. and Halling, Peter J. and Sefiane, Khellil (2016) Fluid-dynamical model for antisurfactants. Physical Review E, 93 (4). 043121. ISSN 1539-3755

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    Abstract

    We construct a fluid-dynamical model for the flow of a solution with a free surface at which surface tension acts. This model can describe both classical surfactants, which decrease the surface tension of the solution relative to that of the pure solvent, and ‘anti-surfactants’ (such as many salts when added to water, and small amounts of water when added to alcohol) which increase it. We demonstrate the utility of the model by considering the linear stability of an infinitely deep layer of initially quiescent fluid. In particular, we predict the occurrence of a novel instability driven by surface-tension gradients, which occurs for anti-surfactant, but not for surfactant, solutions.