Editing Vortex ring (section)

===Separated vortex rings===
[[File:Photos-photos 1088103921 Floating.jpg|thumb|Pappus of the dandelion which produces a separated vortex ring in order to stabilize flight]]
There has been research and experiments on the existence of separated vortex rings (SVR) such as those formed in the wake of the [[Pappus (botany)|pappus]] of a [[Taraxacum|dandelion]]. This special type of vortex ring effectively stabilizes the seed as it travels through the air and increases the lift generated by the seed.<ref>{{Cite journal|last1=Ledda|first1=P. G.|last2=Siconolfi|first2=L.|last3=Viola|first3=F.|last4=Camarri|first4=S.|last5=Gallaire|first5=F.|date=2019-07-02|title=Flow dynamics of a dandelion pappus: A linear stability approach|journal=Physical Review Fluids|volume=4|issue=7|page=071901|doi=10.1103/physrevfluids.4.071901|bibcode=2019PhRvF...4g1901L|issn=2469-990X|hdl=11568/998044|s2cid=198429309 |url=https://research.utwente.nl/en/publications/f98244a1-97b0-4aa2-8a22-bcf113eb8d18 |hdl-access=free}}</ref><ref name=":0">{{Cite journal|last1=Cummins|first1=Cathal|last2=Seale|first2=Madeleine|last3=Macente|first3=Alice|last4=Certini|first4=Daniele|last5=Mastropaolo|first5=Enrico|last6=Viola|first6=Ignazio Maria|last7=Nakayama|first7=Naomi|date=2018|title=A separated vortex ring underlies the flight of the dandelion|journal=Nature|volume=562|issue=7727|pages=414–418|doi=10.1038/s41586-018-0604-2|pmid=30333579|bibcode=2018Natur.562..414C|s2cid=52988814|issn=0028-0836|url=http://eprints.gla.ac.uk/171858/7/171858.pdf}}</ref> Compared to a standard vortex ring, which is propelled downstream, the axially symmetric SVR remains attached to the pappus for the duration of its flight and uses drag to enhance the travel.<ref name=":0" /><ref>{{Cite journal|last=Yamamoto|first=Kyoji|date=November 1971|title=Flow of Viscous Fluid at Small Reynolds Numbers Past a Porous Sphere|journal=Journal of the Physical Society of Japan|volume=31|issue=5|page=1572|doi=10.1143/JPSJ.31.1572|bibcode=1971JPSJ...31.1572Y}}</ref> These dandelion seed structures have been used to create tiny battery-free wireless sensors that can float in the wind and be dispersed across a large area.<ref>{{Cite journal |last1=Iyer |first1=Vikram |last2=Gaensbauer |first2=Hans |last3=Daniel |first3=Thomas L. |last4=Gollakota |first4=Shyamnath |date=2022-03-17 |title=Wind dispersal of battery-free wireless devices |url=https://www.nature.com/articles/s41586-021-04363-9 |journal=Nature |language=en |volume=603 |issue=7901 |pages=427–433 |doi=10.1038/s41586-021-04363-9 |pmid=35296847 |bibcode=2022Natur.603..427I |s2cid=247499662 |issn=0028-0836|url-access=subscription }}</ref>