Berlin 2015 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 38: Wetting, Micro and Nanofluidics (joint session CPP/ DY)
DY 38.10: Vortrag
Mittwoch, 18. März 2015, 17:30–17:45, C 243
Coexistence of Various Instabilities on a Single Liquid Filament — Michael Hein1, •Jean-Baptiste Fleury1, and Ralf Seemann1,2 — 1Saarland University, Experimental Physics, Saarbruecken, Germany — 2Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany
Droplet based microfluidics exploits the decay of a liquid filament or cylinder into droplets of micrometric size. While the physics of droplet breakup on small scales remains a field of vivid interest, droplet based microfluidic systems have become widely used both in fundamental science and application such as (bio-)analytics or micro-chemistry. We present experimental research on the formation of droplets by breakup of a squeezed liquid filament surrounded by an immiscible phase that flows over a topographic step. This non-equilibrium process arises from the interplay between flow properties and interfacial instabilities when the filament is suddenly released from confinement at the step. In contrast to previous studies, a rich variety of different droplet breakup regimes was observed for the used geometry which are characterized by the coexistence of multiple liquid instabilities on a single filament. Surprisingly, these instabilities can be of different type while the filament is exposed to a symmetric flow-field. This spontaneous symmetry breaking is a nontrivial consequence of volume throughput constraints of each individual instability and allows for the specific production of heterogeneous droplet families from one single filament under constant flow rates.
(Michael Hein, Jean-Baptiste Fleury and Ralf Seemann, Submitted)