title: Giant bubble pinch-off.
abstract: Self-similarity has been the paradigmatic picture for the pinch-off of a drop. Here we will show through high-speed imaging and boundary integral simulations that the inverse problem, the pinch-off of an air bubble in water, is not self-similar in a strict sense: A disk is quickly pulled through a water surface, leading to a giant, cylindrical void which after collapse creates an upward and a downward jet. Only in the limiting case of large Froude numbers does the purely inertial scaling h(-logh)(1/4) proportional tau(1/2) for the neck radius h [J. M. Gordillo et al., Phys. Rev. Lett. 95, 194501 (2005)] become visible. For any finite Froude number the collapse is slower, and a second length scale, the curvature of the void, comes into play. Both length scales are found to exhibit power-law scaling in time, but with different exponents depending on the Froude number, signaling the nonuniversality of the bubble pinch-off.
authors.affiliation: Physics of Fluids Group and J.M. Burgers Centre for Fluid Dynamics, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Raymond
authors.initials: R
authors.lastname: Bergmann
authors.forename: Devaraj
authors.initials: D
authors.lastname: van der Meer
authors.forename: Mark
authors.initials: M
authors.lastname: Stijnman
authors.forename: Marijn
authors.initials: M
authors.lastname: Sandtke
authors.forename: Andrea
authors.initials: A
authors.lastname: Prosperetti
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse