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| [[File:Bubble Ring in Sunlight.JPG|thumb|right|300px|{{center|Bubble ring}}]]
| | Marvella is what you can call her but it's not the most feminine title out there. What I adore performing is playing baseball but I haven't produced a dime with it. Years ago we moved to North Dakota and I adore every working day living right here. He utilized to be unemployed but now he is a meter reader.<br><br>Also visit my website [http://santamariaschool.org/content/tips-about-how-overcome-candidiasis-easily santamariaschool.org] |
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| A '''bubble ring''', or '''toroidal bubble''', is an underwater [[vortex ring]] where an air bubble occupies the core of the vortex, forming a ring shape. The ring of air as well as the nearby water spins [[Toroidal and poloidal|poloidally]] as it travels through the water, much like a flexible bracelet might spin when it is rolled on to a person's arm. The faster the bubble ring spins, the more stable it becomes.<ref>Yoona SS and Heister SD (2004) [http://solarcellaerosol.korea.ac.kr/papers/paper-journal/ssyoon5_BLI_PoF2004.pdf "A nonlinear atomization model based on a boundary layer instability mechanism"] ''Physics of Fluids'', '''16''' (1): 47–61.</ref> Bubble rings and [[smoke ring]]s are both examples of [[vortex ring]]s—the physics of which is still under active study in [[fluid dynamics]].<ref>Ruban VP and Rasmussen JJ (2003) [http://link.aps.org/doi/10.1103/PhysRevE.68.056301 "Toroidal bubbles with circulation in ideal hydrodynamics: A variational approach"] ''Phys. Rev'', '''68''' (5).</ref><ref>Wang QX, Yeo KS, Khoo BC and Lam KY (2005) [http://web.mat.bham.ac.uk/Q.X.Wang/papers_pdf/toroidal_bubble_wqx.pdf "Vortex ring modelling of toroidal bubbles"] ''JournalTheoretical and Computational Fluid Dynamics'', '''19''' (5): 1432-2250.</ref> Devices have been invented which generate bubble vortex rings.<ref>United States Patent: [http://www.google.co.nz/patents?hl=en&lr=&vid=USPAT7300040&id=O-KcAAAAEBAJ&oi=fnd&dq=%22ring+bubbles%22&printsec=abstract#v=onepage&q&f=false Simple method for the controlled production of vortex ring bubbles of a gas] Issued patent: 6824125, 30 November 2004.</ref><ref>United States Patent: [http://www.google.co.nz/patents?id=O-KcAAAAEBAJ&printsec=description&zoom=4#v=onepage&q&f=false Simple, mechanism-free device, and method to produce vortex ring bubbles in liquids] Patent number: 7300040. 27 November 2007.</ref>
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| ==Physics==
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| {{external media
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| |video1=[https://www.youtube.com/watch?v=TMCf7SNUb-Q Dolphin play bubble rings] ''[[SeaWorld]]''
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| |video2=[https://www.youtube.com/watch?v=mHyTOcfF99o Extraordinary toroidal vortices] ''YouTube''<ref>Note that although a number of ''YouTube'' videos refer to bubble rings as toroidal vortices, they are in fact [[Toroidal and poloidal|poloidal vortices]]</ref>
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| |video3=[https://www.youtube.com/watch?v=0zriSpg-dpU Bubble ring Time warp - In slow motion] ''YouTube''
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| }}
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| As the bubble ring rises a lift force pointing downward that is generated by the vorticity acts on the bubble in order to counteract the buoyancy force. This reduces the bubbles velocity and increases its diameter. The ring becomes thinner, despite the total volume inside the bubble increasing as the external water pressure decreases.<ref>{{cite journal|last=Cheng|first=M.|coauthors=J. Lou, T.T. Lim|title=Motion of a bubble ring in a viscous fluid|journal=Physics of Fluids|year=2013|volume=25|url=http://scitation.aip.org/docserver/fulltext/aip/journal/pof2/25/6/1.4811407.pdf?expires=1386197422&id=id&accname=freeContent&checksum=F7F77F63D0578CF01E3477EB897B8A08|accessdate=15 October 2013}}</ref> Bubble rings fragment into rings of spherical bubbles when the ring becomes thinner than a few millimetres. This is due to [[Plateau-Rayleigh instability]]. When the bubble reaches a certain thickness, surface tension effects distort the bubble's surface pulling it apart into separate bubbles. Circulation of the fluid around the bubble helps to stabilize the bubble for a longer duration, counteracting the effects of Plateau-Rayleigh instability. Below is the equation for Plateau-Rayleigh instability with circulation as a stabilizing term:
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| ::<math> \omega^2= \left ( \frac{kaK_1}{ka} \right ) \left [ (1-k^2 a^2) \frac{T}{pa^3} - \frac{\Gamma^2}{4\pi^2 a^4} \right ] </math>
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| where ω is the growth rate, k is the wave number, a is the radius of the bubble cylinder, T is the surface tension, Γ is the circulation, and K<small>0</small> and K<small>1</small> are [[Bessel functions]]. When ω is positive the bubble is stable due to circulation and when ω is negative, surface tension effects destabilize it and break it up.<ref>Lundgren TS and Mansour NN (1991) [http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=397147 "Vortex ring bubbles"] ''Journal of Fluid Mechanics'', '''224''':177-196.</ref> Circulation also has an effect on the velocity and radial expansion of the bubble. Circulation increases the velocity while reducing the rate of radial expansion. Radial expansion however is what diffuses energy by stretching the vortex.<ref>{{cite journal|last=Cheng|first=M.|coauthors=J. Lou, T.T. Lim|title=Motion of a bubble ring in a viscous fluid|journal=Physics of Fluids|year=2013|volume=25|url=http://scitation.aip.org/docserver/fulltext/aip/journal/pof2/25/6/1.4811407.pdf?expires=1386197422&id=id&accname=freeContent&checksum=F7F77F63D0578CF01E3477EB897B8A08|accessdate=15 October 2013}}</ref> Instability happens more quickly in turbulent water, but in calm water divers can achieve an external diameter of a metre or more before the bubble fragments.
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| ===Buoyancy induced toroidal bubbles===
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| As an air bubble rises, there is a difference in pressure between the top and bottom of the bubble. The higher pressure at the bottom of the bubble pushes the bubble's bottom surface up faster than the top surface rises. This creates a fluid jet that moves up through the center of the bubble. If the fluid jet has enough energy, it will puncture the top of the bubble and create a bubble ring. Because of the motion of the fluid moving through the center of the bubble, the bubble begins to rotate. This rotation moves the fluid around the bubble creating a toroidal vortex. If the surface tension of the fluid interface or the viscosity of the liquid is too high, then the liquid jet will be more broad and will not penetrate the top of the bubble. This results in a spherical cap bubble.<ref>{{cite journal|last=Chen|first=Li|coauthors=Suresh V. Garimella, John A. Reizes, Eddie Leonardi|title=The development of a bubble rising in a viscous liquid|journal=Journal of Fluid Mechanics|year=1999|volume=387|pages=61–96|accessdate=15 October 2013}}</ref> Air bubbles with a diameter greater than about two centimeters become toroidal in shape due to the pressure differences.<ref>{{Cite journal |title=Ring Bubbles of Dolphins|author1=Ken Marten |author2=Karim Shariff |author3=Suchi Psarakos |author4=Don J. White |journal=Scientific American |url=http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=D0CD2470-180D-4C42-88B6-654E90AB55D}}.</ref>
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| ===Cavitation bubbles===
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| [[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.|coauthors=G.S. Keen, A. Vogel, J.R. Blake|title=The final stage of the collapse of a cavitation bubble close to a rigid boundary|journal=Physics of Fluids|year=January|month=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|accessdate=21 October 2013}}</ref>
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| <gallery widths=200>
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| 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
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| File:Bubble-ring-spin.png|The bubble ring travels in the same direction its innermost side rotates
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| File:Nicobulle.JPG|A underwater diver blows a bubble ring
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| </gallery>
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| {{clear}}
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| ==Cetaceans==
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| [[Cetacean]]s, such as [[beluga whale]]s, [[dolphin]]s and [[humpback whale]]s, blow bubble rings. Dolphins sometimes engage in complex play behaviours, creating bubble rings on purpose, seemingly for amusement.<ref>{{cite web | url=http://www.deepocean.net/deepocean/index.php?science09.php | title=The physics of bubble rings and other diver's exhausts|accessdate=2006-10-24}}</ref> There are two main methods of bubble ring production: rapid puffing of a burst of air into the water and allowing it to rise to the surface, forming a ring; or creating a toroidal vortex with their flukes and injecting a bubble into the [[helical]] vortex currents thus formed. The dolphin will often then examine its creation visually and with sonar. They will sometimes play with the bubbles, distorting the bubble rings, breaking smaller bubble rings off of the original or splitting the original ring into two separate rings using their beak. They also appear to enjoy biting the vortex-rings they've created, so that they burst into many separate normal bubbles and then rise quickly to the surface. Dolphins also have the ability to form bubble rings with their flukes by using the reservoir of air at the surface.<ref>{{cite web | url=http://www.bubblerings.com/bubblerings/media.cfm | title=Bubble rings: Videos and Stills | accessdate=2006-10-24}}</ref>
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| {{clear}}
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| <gallery widths=200>
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| File:Delphinapterus leucas Bubble Ring.JPG|[[Beluga whale]]s blowing bubble rings
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| File:Humpback-bubble-spiral Olson.jpg|Aerial view of a [[Humpback whale|humpback]] [[Humpback whale#Feeding and predation|bubble net]]
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| </gallery>
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| [[Humpback whale]]s use another type of bubble ring when they forage for fish. They surround a [[Shoaling and schooling|school]] of [[forage fish]] with a circular [[Humpback whale#Feeding|bubble net]] and herd them into a [[bait ball]].<ref>{{cite news
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| |first=Deb
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| |last=Acklin
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| |title= Crittercam Reveals Secrets of the Marine World
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| |url=http://news.nationalgeographic.com/news/2002/06/0624_020624_TVbubble.html
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| |work=
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| |publisher= National Geographic News
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| |date=2005-08-05
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| |accessdate=2007-11-01 }}</ref>
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| ==Human divers==
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| [[File:Soapbubbles-SteveEF.jpg|thumb|right|Boy blowing soap bubbles from a bubble ring]]
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| Some [[scuba divers]] and [[free-diving|freedivers]] can create bubble rings by blowing air out of their mouth in a particular manner. Long bubble rings also can form spontaneously in turbulent water such as heavy surf.
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| ==Other uses of the term==
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| The term "bubble ring" is also used in other contexts. A common children's toy for blowing soap bubbles is called a bubble ring, and replaces the [[bubble pipe]] toy that was traditionally used for many years. Soapsuds are suspended on a ring connected by a stem to the screwcap of a bottle containing soapsuds.<ref>Erhard G (2006) [http://books.google.co.nz/books?id=mesU4WbE5CIC&pg=PA277&dq=%22bubble+ring%22|%22bubble+rings%22&hl=en&ei=R835S7iKLtCXcb7o_eYL&sa=X&oi=book_result&ct=result&resnum=39&ved=0CNcBEOgBMCY#v=onepage&q=%22bubble%20ring%22|%22bubble%20rings%22&f=false ''Designing with plastics''] Page 227. Hanser Verlag. ISBN 978-1-56990-386-5</ref>
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| ==See also==
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| * [[Carousel feeding]]
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| * [[Smoke ring]]
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| * [[Vortex ring toys]]
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| {{clear}}
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| ==References==
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| {{reflist|32em}}
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| ==Further references==
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| * Das1 D and Kumar V (2005) [http://pdf.aiaa.org/preview/CDReadyMAERO05_1140/PV2005_2953.pdf "Experimental Investigation of the Trajectory of Compressible Vortex Rings"] 11th AIAA/CEAS Aeroacoustics Conference (26th AIAA Aeroacoustics Conference).
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| * Hameroff SR, Kaszniak AW and Scott A (1998) [http://books.google.co.nz/books?id=dliyExsqYGwC&pg=PA558&dq=%22bubble+ring%22|%22bubble+rings%22&hl=en&ei=R835S7iKLtCXcb7o_eYL&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFgQ6AEwCQ#v=onepage&q=%22bubble%20ring%22|%22bubble%20rings%22&f=false ''Toward a science of consciousness II: the second Tucson discussions and debates''] Page 558. MIT Press. ISBN 978-0-262-08262-4.
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| * Lundgren TS and Mansour NN (1991) [http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=397147 "Vortex ring bubbles"] ''Journal of Fluid Mechanics'', '''224''':177-196.
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| * Marten K, Shariff K, Psarakos S and White DJ (1996) “Ring bubbles of dolphins. A number of bottlenose dolphins in Hawaii can create shimmering, stable rings and helices of air as part of play” ''Scientific American'', '''275''' (2): 82-87.
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| * McCowan B, Marino L, Vance E, Walke L and Reiss D (2000) [http://faculty.vetmed.ucdavis.edu/faculty/bjmccowan/Pubs/McCowanetal.JCP.2000.pdf "Bubble Ring Play of Bottlenose Dolphins (Tursiops truncatus): Implications for Cognition"] ''Journal of Comparative Psychology'', '''l14''' (1):98-106.
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| == External links ==
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| {{Commons category|Bubble rings}}
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| * [http://earthtrust.org/delringgallery.html Dolphin bubble rings]
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| * [http://www.metacafe.com/watch/1041454/dolphin_play_bubble_rings/ Dolphin bubble rings (video)]
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| * [https://www.youtube.com/watch?v=quiDUHNsq2E Dolphin make and play bubble rings (video)]
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| * [https://www.youtube.com/watch?v=TMCf7SNUb-Q&feature=related Dolphin play bubble rings (video)]
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| * [http://bubblerings.com/bubblerings/media.cfm Various videos of bubble rings]
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| *[http://www.bubblerings.com/ BubbleRings.com]
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| [[Category:Vortices]]
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Marvella is what you can call her but it's not the most feminine title out there. What I adore performing is playing baseball but I haven't produced a dime with it. Years ago we moved to North Dakota and I adore every working day living right here. He utilized to be unemployed but now he is a meter reader.
Also visit my website santamariaschool.org