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 language | English (US) |
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Article number | 54002 |
Journal | Europhysics Letters |
Volume | 92 |
Issue number | 5 |
DOIs | |
State | Published - Dec 2010 |
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)