Editing Bubble ring (section)

===Cavitation bubbles===
[[Cavitation]] bubbles, when near a solid surface, can also become a torus. The area away from the surface has an increased static pressure causing a high pressure jet to develop. This jet is directed towards the solid surface and breaks through the bubble to form a torus shaped bubble for a short period of time. This generates multiple shock waves that can damage the surface.<ref>{{cite journal|last=Brujan|first=E.A.|author2=G.S. Keen|author3=A. Vogel|author4=J.R. Blake|title=The final stage of the collapse of a cavitation bubble close to a rigid boundary|journal=Physics of Fluids|date=January 2002|volume=14|issue=1|url=http://www.bmo.uni-luebeck.de/uploads/tx_wapublications/Brujan__2002_Physics_of_Fluids_The_final_stage_of_the_collapse_of_a_cavitation_bubble_close_to_a_rigid_boundary.pdf|access-date=21 October 2013|doi=10.1063/1.1421102|pages=85|bibcode=2002PhFl...14...85B|s2cid=13668310 |archive-url=https://web.archive.org/web/20160429211955/http://www.bmo.uni-luebeck.de/uploads/tx_wapublications/Brujan__2002_Physics_of_Fluids_The_final_stage_of_the_collapse_of_a_cavitation_bubble_close_to_a_rigid_boundary.pdf|archive-date=29 April 2016|url-status=dead}}</ref>

<gallery mode="packed" style="float:left" heights="120">
File:Vortex ring.gif|A bubble ring forms a [[vortex ring]], shaped like a doughnut which spins [[Toroidal and poloidal|poloidally]] in the direction of the arrows.
File:Bubble-ring-spin.png|The bubble ring travels in the same direction its innermost side rotates.
</gallery>

<gallery mode="packed" style="float:right" heights="160">
File:Nicobulle.JPG|An underwater diver blows a bubble ring.
File:Scuba diver produces a bubble ring 2018-03-07.jpg|A [[scuba diver]] blows a bubble ring.
</gallery>

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