Universality
A long-standing controversy in the fluid dynamics community until recently has been the pinch-off behavior of a bubble inside a liquid. Our simulations in Gekle et al. Phys. Rev. E 80, 036305 (2009), extending over 12 decades in time, suggest that various systems eventually follow the universal behavior predicted in Eggers et al. Phys. Rev. Lett. 2007, at least under idealized conditions neglecting air dynamics. However, we find that the time scale for the onset of this final regime varies by orders of magnitude depending on the system in question. This observation reconciles the different views expressed in recent literature about bubble pinch-off.
Figure 1: Various pinch-off systems follow the same universal behavior (dashed red line) after an initiation process (time goes from right to left here). The systems here are (i): Impacting disk, (ii): Gas injection through an orifice, (iii): Bubble in a straining flow, (iv): Initially necked bubble.
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Info: Devaraj van der Meer