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Exit dynamics of a sphere launched underneath a liquid bath surface

par Wei, Xiaofeng;Li, Dege;Lei, Jing;Li, Jinglu;Rivero Rodriguez, Javier ;Lin, Fangye;Wang, Dongyun;Scheid, Benoît
Référence Physical Review Fluids, 9, 5, 054003
Publication Publié, 2024-12-01

Article révisé par les pairs

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Résumé :

In this paper, we investigate the exit dynamics of a sphere launched underneath a liquid bath surface at a prescribed impact velocity. Spheres with radii approximate or smaller than the capillary length are considered. Following our previous work of a ligament drawn of a liquid bath [J. Fluid Mech. 922, A14 (2021)0022-112010.1017/jfm.2021.505], a two-dimensional model is applied to describe the liquid dynamics, and the whole exit dynamics up to the descent or the pinch-off moments is considered. The process can be sequenced into a partial exit stage that forms a coated layer and a full exit stage with an attached ligament. A bouncing-off regime, a lower pinch-off penetration regime, and an upper pinch-off penetration regime are identified, separating by a penetration Weber number and a switching Weber number. The phase diagram is revealed, where the two critical Weber numbers are functions of the Bond number. By considering the energy evolutions, we show that the impact energy is mainly converted into the surface energy and the gravitational potential energy for the low- and large-gravity cases, respectively. The coated layer is mainly formed in the partial exit stage, whose maximum volume increases with the impact velocity but decreases with gravity effect. Stretching motion is shown to have negligible influence on the local pinch-off behavior, while it determines the appearance and the location of pinch-off. Our results can help to understand the exit behaviors of aquatic animals, and the design of microamphibious aircraft or energy collection devices.