Spreading, retraction, and sustained oscillations of surfactant-laden lenses

We examine the dynamics of surfactant laden-lenses spreading over liquid substrates. We use the lubrication theory in combination with models for the spreading process, the effects of surfactant at the contact line and the sorption kinetics above and below the critical micelle concentration. Our model is solved numerically using a finite-element formulation. We carry out a full parametric study and simulate a wide range interesting behaviour ranging from complete spreading of the lens, to spreading followed by retraction, to sustained pulsating oscillations.