Droplet breakup in flow past an obstacle: A capillary instability due to permeability variations

S. Protière, M. Z. Bazant, D. A. Weitz, Howard A. Stone

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

In multiphase flow in confined geometries an elementary event concerns the interaction of a droplet with an obstacle. As a model of this configuration we study the collision of a droplet with a circular post that spans a significant fraction of the cross-section of a microfluidic channel. We demonstrate that there exist conditions for which a drop moves completely around the obstacle without breaking, while for the same geometry but higher speeds the drop breaks. Therefore, we identify a critical value of the capillary number above which a drop will break. We explain the results with a one-dimensional model characterizing the flow in the narrow gaps on either side of the obstacle, which identifies a surface-tension-driven instability associated with a variation in the permeability in the flow direction. The model captures the major features of the experimental observations.

Original languageEnglish (US)
Article number54002
JournalEurophysics Letters
Volume92
Issue number5
DOIs
StatePublished - Dec 2010

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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