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Flow of a thin liquid layer due to ambient disturbances

1987; Wiley; Volume: 33; Issue: 5 Linguagem: Inglês

10.1002/aic.690330513

1547-5905

Kenneth J. Ruschak,

Surfactants and Colloidal Systems

Abstract A closed‐form solution for the transient deformation of a thin liquid layer caused by ambient pressure disturbances predicts the level of disturbances that will produce significant flow in the time available. The effects of viscosity, gravity, surface tension, and a soluble surface‐active agent are included in the analysis. The major simplification is the use of the lubrication approximation to the equations of flow. Nearly stationary pressure disturbances are found to be more dangerous than moving disturbances. Surface tension gradients arising from convection of surfactant in the surface oppose flow and reduce the film deformation. The thermodynamic properties of the surfactant, as well as its diffusion coefficient, are important in determining whether significant surface tension gradients develop. However, the effectiveness of a surfactant at minimizing film deformation also depends upon flow parameters such as the natural time scale for flow.