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Models for a Vertical Draining Film with an Insoluble Surfactant


Speaker: Richard Braun, Unversity of Delaware
Location: 693 Kerr
Start time: Mon, Oct 22 2001, 4:00PM

The drainage of the thin fluids layers, or lamellae, in a foam may be modeled by a vertical draining thin liquid film. A sequence of mathematical models is described that attempts to explain some aspects of the drainage of the film. Lubrication theory is used to derive the nonlinear PDEs that describe the film; all models assume an insoluble surfactant. The models include effects from gravity, viscosity, surface tension and its dependence on surface concentration (the Marangoni effect), and surface viscosity; they may also include nonlinear equations of state. The models are able to predict very well the fast and slow limits of the drainage observed experimentally; a limited range of intermediate drainage rates has been described by these models to date. The limitations of the models and possible extensions will be discussed.

Coffee and cookies will be served at 3:30.