█ Bubble jet

Younjoung Kang & Yeunwoo Cho, Journal of Fluid Mechanics, 2019, 866, pp.841-864

When an underwater bubble is generated close to a free surface, the resultant surface wave shows an overall rising jet-like behaviour. During this event, the initial spherical bubble expands, collapses and evolves into a non-spherical bubble (a dented sphere, a hemisphere, a spherical frustum or a toroid), migrating downwards away from the free surface; some parts of the bubble are disintegrated and are left behind. The overall behaviour of the bubble and the surface wave altogether can be understood in the context of the action-reaction momentum principle. We study on jet-like surface waves generated by an electric-spark-generated underwater bubble.

• Application areas: Jet printing, Droplet separation, Micro-surface cleaning, Laser-based printing techniques, Underwater explosions
 
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