Gekle Stephan, Snoeijer Jacco H, Lohse Detlef, van der Meer Devaraj
Department of Applied Physics and J.M. Burgers Centre for Fluid Dynamics, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Sep;80(3 Pt 2):036305. doi: 10.1103/PhysRevE.80.036305. Epub 2009 Sep 4.
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 disk, (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 by J. Eggers [Phys. Rev. Lett. 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 disk 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.
在四种物理情形下，对被无粘性流体包围的轴对称气泡的 pinch-off 进行了比较：(i) 冲击盘尾流中的腔体坍塌；(ii) 通过小孔注入的气泡；(iii) 应变流中的气泡破裂；(iv) 初始呈颈状的气泡。我们的边界积分模拟表明，所有系统最终都遵循由 J. Eggers [《物理评论快报》98, 094502 (2007)] 预测的具有缓慢变化指数的普遍行为。然而，发现进入这一最终状态的时间尺度根据所讨论的系统不同而相差几个数量级。对于冲击盘，该时间尺度处于毫秒范围内，而对于气体注入针，普遍行为在 pinch-off 前仅几微秒才开始出现。这些发现调和了近期文献中关于气泡 pinch-off 普遍性的不同观点。
