Droplet detachment and bead formation in visco-elastic fluids

The presence of a very small amount of high molecular weight polymer significantly delays the pinch-off singularity of a drop of water falling from a faucet, and leads to the formation of a long-lived cylindrical filament. In this paper we present experiments, numerical simulations, and theory which examines the pinch-off process in the presence of polymers. The numerical simulations are found to be in excellent agreement with experiment. As a test case, we establish the conditions under which a small bead remains on the filament; we find that this is due to the asymmetry induced by the self-similar pinch-off of the droplet.