video: Evolution of neck shrinkage and eventual bubble pinch-off in a capillary tube. view more
Credit: Movie courtesy of Amir A. Pahlavan.
A study explores the dynamics of the physical process by which bubbles pinch off. The pinch-off of a bubble involves formation of a singularity, which is expected to be independent of the details of the experimental setup and thus to exhibit universal dynamics. However, bubble pinch-off has been shown to be nonuniversal when it occurs in a large tank of viscous liquid. Ruben Juanes and colleagues explored the dynamics of bubble formation and pinch-off in the highly confined conditions within a capillary tube. Whereas in a large tank the neck of the bubble contracts linearly with time, the neck of the bubble in a capillary tube contracted in 2 distinct stages. Initially, the neck radius varied with the 1/5 power of time, before transitioning to a linear dependence on time shortly before pinch-off. Unlike the case of liquid in a large tank, bubble formation in the capillary tube was insensitive to the details of the experimental conditions. The first stage of pinch-off, driven by movement of the contact line where liquid, gas, and solid phases meet, effectively erases the memory of the system, leading to universal dynamics. According to the authors, the results have implications for bubble and drop formation in confined conditions, such as in microfluidic technology and geophysics.
Article #18-19744: "Restoring universality to the pinch-off of a bubble," by Amir A. Pahlavan, Howard A. Stone, Gareth H. McKinley, and Ruben Juanes.
MEDIA CONTACT: Ruben Juanes, Massachusetts Institute of Technology, Cambridge, MA; tel: 617-253-7191; e-mail: juanes@mit.edu
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Journal
Proceedings of the National Academy of Sciences