(353e) Dynamics of Drop Formation in Microchannels: Polymeric Fluids, Micellar Solutions, & Tip-Streaming

Arratia, P. E. - Presenter, University of Pennsylvania

The dynamics of drop formation of polymeric fluids and micellar solutions in microchannels are investigated in experiments. Both viscoelasticity and surface tension are found to strongly affect the drop breakup dynamics in a 50 um square-channel. Elastic stresses produce a wealth of interesting phenomena, including tip-streaming, 'beads-on-string', and iterated stretching. The presence of surfactant leads to tip-streaming behavior in viscoelastic fluids that is quite different from the Newtonian counterpart at similar viscosity and capillary number. We quantify our observation by measuring the relevant length and time scales of the system. Simple scaling arguments are provided based on such measurements.