Approach to Universality in Axisymmetric Bubble Pinch-Off

TL;DR

This study compares four physical realizations of axisymmetric bubble pinch-off, demonstrating that they all eventually follow a universal behavior, with the onset timing varying significantly across different systems.

Contribution

The paper shows that diverse bubble pinch-off scenarios converge to a universal behavior, with onset times depending on the specific physical setup.

Findings

All systems follow universal behavior predicted by prior theory.

Onset time for universal behavior varies from microseconds to milliseconds.

Reconciles differing views on bubble pinch-off universality.

Abstract

The pinch-off of an axisymmetric air bubble surrounded by an inviscid fluid is compared in four physical realizations: (i) cavity collapse in the wake of an impacting disc, (ii) gas bubbles injected through a small orifice, (iii) bubble rupture in a straining flow, and (iv) a bubble with an initially necked shape. Our boundary-integral simulations suggest that all systems eventually follow the universal behavior characterized by slowly varying exponents predicted in [Eggers et al., PRL 98, 094502 (2007)]. However, the time scale for the onset of this final regime is found to vary by orders of magnitude depending on the system in question: while for the impacting disc it is well in the millisecond range, for the gas injection needle universal behavior sets in only a few microseconds before pinch-off. These findings reconcile the different views expressed in recent literature about the universal nature of bubble pinch-off.