The experimental setup.
(a) Large bubble entrapment sequence for a drop impact on the restricted liquid surface. The inner diameter of glass tube D t is 8 mm, D t * = 2.07. (b) A drop impact on a liquid pool (8 × 8 × 10 cm3). Both impact heights H are 49 mm, impact velocities 0.92 m/s, and drop diameters D are 3.86 mm.
The We to Fr plot of primary and large bubble entrapment region. The limits of high-speed jet and primary bubble entrapment are reproduced from Liow's figure.10 The large bubble entrapment region for free surface refers to Pumphrey and Elmore.7 The terminal velocity line refers to Dingle and Lee.23
The plot of large bubble entrapment region: (a) We to D t * and (b) K to D t * . The region of large bubble formation is not continuous and scatters at some discrete range, and the “error bar” denotes the limit of where the bubble is observed to be entrapped.
The periodic appearance of large bubble entrapment. The two sinusoidal traces show the different drop shape at the moment of impact, which refer to drops with D = 3.86 mm and D = 2.64 mm, respectively. The notations and “error bars” denote the large bubble entrapment region in experiments. The pictures of drop with different falling time (released from different height) are captured at the moment of contact with liquid surface.
Size of entrapped large bubble.
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