Editing Turbulence (section)

== Examples of turbulence ==
[[File:Los Angeles attack sub 2.jpg|thumb|right|[[Laminar flow|Laminar]] and turbulent water flow over the hull of a submarine. As the relative velocity of the water increases turbulence occurs.]]
[[File:Airplane vortex edit.jpg|thumb|right|Turbulence in the [[Wingtip vortices|tip vortex]] from an [[airplane]] wing passing through coloured smoke ]]
* Smoke rising from a [[cigarette]]. For the first few centimeters, the smoke is [[Laminar flow|laminar]]. The smoke [[Plume (fluid dynamics)|plume]] becomes turbulent as its Reynolds number increases with increases in flow velocity and characteristic length scale.
* Flow over a [[golf ball]]. (This can be best understood by considering the golf ball to be stationary, with air flowing over it.) If the golf ball were smooth, the [[boundary layer]] flow over the front of the sphere would be laminar at typical conditions. However, the boundary layer would separate early, as the pressure gradient switched from favorable (pressure decreasing in the flow direction) to unfavorable (pressure increasing in the flow direction), creating a large region of low pressure behind the ball that creates high [[form drag]]. To prevent this, the surface is dimpled to perturb the boundary layer and promote turbulence. This results in higher skin friction, but it moves the point of boundary layer separation further along, resulting in lower drag.
*[[Clear-air turbulence]] experienced during airplane flight, as well as poor [[astronomical seeing]] (the blurring of images seen through the atmosphere).
* Most of the terrestrial [[atmospheric circulation]].
* The oceanic and atmospheric [[mixed layer]]s and intense oceanic currents.
* The flow conditions in many industrial equipment (such as pipes, ducts, precipitators, gas [[scrubber]]s, [[dynamic scraped surface heat exchanger]]s, etc.) and machines (for instance, [[internal combustion engine]]s and [[gas turbine]]s).
* The external flow over all kinds of vehicles such as cars, airplanes, ships, and submarines.
* The motions of matter in stellar atmospheres.
* A jet exhausting from a nozzle into a quiescent fluid. As the flow emerges into this external fluid, shear layers originating at the lips of the nozzle are created. These layers separate the fast moving jet from the external fluid, and at a certain critical Reynolds number they become unstable and break down to turbulence.
* Biologically generated turbulence resulting from swimming animals affects ocean mixing.<ref>{{Cite journal |title = Observations of Biologically Generated Turbulence in a Coastal Inlet |url = https://www.science.org/doi/10.1126/science.1129378 |journal = Science |date = 22 September 2006 |issn = 0036-8075 |pmid = 16990545 |pages = 1768–1770 |volume = 313 |issue = 5794 |doi = 10.1126/science.1129378 |language = en |first1 = Eric |last1 = Kunze |first2 = John F. |last2 = Dower |first3 = Ian |last3 = Beveridge|first4 = Richard |last4 = Dewey |first5 = Kevin P. |last5 = Bartlett |bibcode = 2006Sci...313.1768K |s2cid = 33460051}}</ref>
* [[Snow fence]]s work by inducing turbulence in the wind, forcing it to drop much of its snow load near the fence.
* Bridge supports (piers) in water. When river flow is slow, water flows smoothly around the support legs. When the flow is faster, a higher Reynolds number is associated with the flow. The flow may start off laminar but is quickly separated from the leg and becomes turbulent.
* In many geophysical flows (rivers, atmospheric boundary layer), the flow turbulence is dominated by the coherent structures and turbulent events. A turbulent event is a series of turbulent fluctuations that contain more energy than the average flow turbulence.<ref name="Narasimha">{{cite journal |last1=Narasimha |first1=R. |last2=Rudra Kumar |first2=S. |last3=Prabhu |first3=A. |last4=Kailas |first4=S. V. |title= Turbulent flux events in a nearly neutral atmospheric boundary layer |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |volume=365 |issue=1852 |pages=841–858 |year=2007 | doi=10.1098/rsta.2006.1949 |pmid=17244581 |bibcode = 2007RSPTA.365..841N |s2cid=1975604 |url=http://repository.ias.ac.in/24526/1/322.pdf}}</ref><ref name="Trevethan_Chanson">{{cite journal |last1=Trevethan |first1=M. |author2-link=Hubert Chanson |last2=Chanson |first2=H. |title= Turbulence and Turbulent Flux Events in a Small Estuary |journal=[[Environmental Fluid Mechanics]] |issue=3 |volume=10 |pages=345–368 |year=2010 |doi=10.1007/s10652-009-9134-7 |bibcode=2010EFM....10..345T |s2cid=7680175 |url=http://espace.library.uq.edu.au/view/UQ:205133}}</ref> The turbulent events are associated with coherent flow structures such as eddies and turbulent bursting, and they play a critical role in terms of sediment scour, accretion and transport in rivers as well as contaminant mixing and dispersion in rivers and estuaries, and in the atmosphere.
{{unsolved|physics|Is it possible to make a theoretical model to describe the behavior of a turbulent flow—in particular, its internal structures?}}
*In the medical field of [[cardiology]], a stethoscope is used to detect [[heart sounds]] and [[bruits]], which are due to turbulent blood flow. In normal individuals, heart sounds are a product of turbulent flow as heart valves close. However, in some conditions turbulent flow can be audible due to other reasons, some of them pathological. For example, in advanced [[atherosclerosis]], bruits (and therefore turbulent flow) can be heard in some vessels that have been narrowed by the disease process.
* Recently, turbulence in porous media became a highly debated subject.<ref>{{cite journal |last1=Jin |first1=Y. |last2=Uth |first2=M.-F. |last3=Kuznetsov |first3=A. V. |last4=Herwig |first4=H. |title=Numerical investigation of the possibility of macroscopic turbulence in porous media: a direct numerical simulation study |journal=Journal of Fluid Mechanics |date=2 February 2015 |volume=766 |pages=76–103 |doi=10.1017/jfm.2015.9 |bibcode = 2015JFM...766...76J |s2cid=119946306}}</ref>
* Strategies used by animals for olfactory navigation, and their success, are heavily influenced by turbulence affecting the odor plume.<ref name="Mackenzie">{{cite journal |last1=Mackenzie |first1=Dana |title=How animals follow their nose |journal=Knowable Magazine |publisher=Annual Reviews |date=6 March 2023 |doi=10.1146/knowable-030623-4 |doi-access=free |url=https://knowablemagazine.org/article/living-world/2023/how-animals-follow-their-nose |access-date=13 March 2023 |language=en}}</ref><ref name="Reddy">{{cite journal |last1=Reddy |first1=Gautam |last2=Murthy |first2=Venkatesh N. |last3=Vergassola |first3=Massimo |title=Olfactory Sensing and Navigation in Turbulent Environments |journal=Annual Review of Condensed Matter Physics |date=10 March 2022 |volume=13 |issue=1 |pages=191–213 |doi=10.1146/annurev-conmatphys-031720-032754 |bibcode=2022ARCMP..13..191R |s2cid=243966350 |url=https://www.annualreviews.org/doi/10.1146/annurev-conmatphys-031720-032754 |access-date=13 March 2023 |language=en |issn=1947-5454}}</ref>
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