Stability of Shapes Held by Surface Tension and Subjected to Flow

Results of three problems are summarized in this contribution. Each involves the fundamental capillary instability of an interfacial bridge and is an extension of previous work. The first two problems concern equilibrium shapes of liquid bridges near the stability boundary corresponding to maximum length (PlateauRayleigh limit). For the first, a previously formulated nonlinear theory to account for imposed gravity and interfacial shear disturbances in an isothermal environment [1,2] is quantitatively tested in experiment. For the second problem, the liquid bridge is subjected to a shear that models the effect of a thermocapillary flow generated by a ring heater in a liquid encapsulated float-zone configuration[3]. In the absence of gravity, this symmetric perturbation can stabilize the bridge to lengths on the order of 30% beyond the Plateau-Rayleigh (PR) limit, which is on the order of heretofore unexplained shuttle observations. The third problem considers the dynamics of collapse and pinchoff of a film bridge (no gravity) --what happens in the absence of stabilization. Here we summarize experimental efforts to measure the self-similar cone-and-crater structure predicted by a previous theory[4].