Droplet Breakup in Flow Past an Obstacle: A Capillary Instability Due to Permeability Variations
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Author(s)
Protière, S.
Bazant, Martin Z.
Weitz, D. A.
Stone, H. A.
Date Issued
December 2010
Journal
EPL (Europhysics Letters)
Publisher
Institute of Physics Publishing
Citation
Protière, S. et al. “Droplet Breakup in Flow Past an Obstacle: A Capillary Instability Due to Permeability Variations.” EPL (Europhysics Letters) 92.5 (2010): 54002.
Version
Author's final manuscript
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.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mathematics
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Creative Commons Attribution-Noncommercial-Share Alike 3.0
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DOI of Published Version
https://doi.org/10.1209/0295-5075/92/54002
