Droplet detachment and bead formation in visco-elastic fluids

TL;DR

This paper investigates how small amounts of high molecular weight polymers affect droplet pinch-off and bead formation in visco-elastic fluids through experiments, simulations, and theory, revealing the conditions for bead retention on filaments.

Contribution

It provides a combined experimental, numerical, and theoretical analysis of droplet pinch-off in visco-elastic fluids, highlighting the role of polymers in delaying pinch-off and causing bead formation.

Findings

Polymer presence delays pinch-off and creates long-lived filaments.

Numerical simulations match experimental results closely.

Conditions for bead retention on the filament are identified.

Abstract

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.