Forced Wetting Transition and Bubble Pinch-Off in a Capillary Tube
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Univ. of Toronto, ON (Canada)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Technical Univ. of Madrid, Madrid (Spain)
Immiscible fluid-fluid displacement in partial wetting continues to challenge our microscopic and macroscopic descriptions. In this study, we investigate 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 detail 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.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FE0013999; SC0018357
- OSTI ID:
- 1505591
- Alternate ID(s):
- OSTI ID: 1422435
- Journal Information:
- Physical Review Letters, Vol. 120, Issue 8; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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