STOKES-FLOW AT INFINITE MARANGONI NUMBER - EXACT-SOLUTIONS FOR THE SPREADING AND COLLAPSE OF A SURFACTANT

The spatio-temporal evolution of an active scalar in surface-tension-d riven flow is studied using a recently developed self-consistent nonli near model. In the one-dimensional case an exact similarity solution i s found which, depending on the initial conditions, describes the spre ading or the finite-time collapse of the scalar. The time-dependence o f the width of the surfactant distribution can be qualitatively unders tood from basic fluid-dynamical principles. The possibility of experim ental verification of the theoretical prediction is briefly discussed.