Fig. 4.

Axial radius of curvature versus time. The evolution of the axial radius of curvature $r_c$ versus time to the pinch-off shows that as the point of pinch-off is approached, the curvature asymptotes to a constant value (symbols are the same as in Fig. 2). (A) The time evolution of axial radius of curvature is independent of the flow rate but changes when the liquid viscosity or the tube diameter is varied. (B) The data corresponding to all 12 experiments collapse on a single curve when the nondimensional axial radius of curvature is plotted against the nondimensional minimum neck diameter. The nondimensional late-time axial radius of curvature asymptotes to a universal constant $\underset{\tilde{\tau }\to 0}{lim}{\tilde{r}}_c\left(\tilde{\tau }\right)={\tilde{r}}_{cf}\approx 0.07$.