Forced Wetting Transition and Bubble Pinch-Off in a Capillary Tube
Name
PhysRevLett.120.084501.pdf
Size
1.02 MB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Zhao, Benzhong
Alizadeh Pahlavan, Amir
Cueto-Felgueroso Landeira, Luis
Juanes, Ruben
Date Issued
February 2018
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Zhao, Benzhong et al. "Forced Wetting Transition and Bubble Pinch-Off in a Capillary Tube." Physical Review Letters 120, 8 (February 2018): 084501 © 2018 American Physical Society
Version
Final published version
Abstract
Immiscible fluid-fluid displacement in partial wetting continues to challenge our microscopic and macroscopic descriptions. Here, we study the displacement of a viscous fluid by a less viscous fluid in a circular capillary tube in the partial wetting regime. In contrast with the classic results for complete wetting, we show that the presence of a moving contact line induces a wetting transition at a critical capillary number that is contact angle dependent. At small displacement rates, the fluid-fluid interface deforms slightly from its equilibrium state and moves downstream at a constant velocity, without changing its shape. As the displacement rate increases, however, a wetting transition occurs: the interface becomes unstable and forms a finger that advances along the axis of the tube, leaving the contact line behind, separated from the meniscus by a macroscopic film of the viscous fluid on the tube wall. We describe the dewetting of the entrained film, and show that it universally leads to bubble pinch-off, therefore demonstrating that the hydrodynamics of contact line motion generate bubbles in microfluidic devices, even in the absence of geometric constraints.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
http://dx.doi.org/10.1103/PhysRevLett.120.084501
