Kelvin–Helmholtz instability
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (March 2010) |
The Kelvin–Helmholtz instability (after
Theory overview and mathematical concepts
If the density and velocity vary continuously in space (with the lighter layers uppermost, so that the fluid is RT-stable), the dynamics of the Kelvin-Helmholtz instability is described by the Taylor–Goldstein equation:
Numerically, the Kelvin–Helmholtz instability is simulated in a temporal or a spatial approach. In the temporal approach, the flow is considered in a periodic (cyclic) box "moving" at mean speed (absolute instability). In the spatial approach, simulations mimic a lab experiment with natural inlet and outlet conditions (convective instability).
Discovery and history
The existence of the Kelvin-Helmholtz instability was first discovered by German physiologist and physicist Hermann von Helmholtz in 1868. Helmholtz identified that "every perfect geometrically sharp edge by which a fluid flows must tear it asunder and establish a surface of separation".
Throughout the early 20th Century, the ideas of Kelvin-Helmholtz instabilities were applied to a range of stratified fluid applications. In the early 1920s,
Geophysical observations of the Kelvin-Helmholtz instability were made through the late 1960s/early 1970s, for clouds,[7] and later the ocean. [8]
See also
- Rayleigh–Taylor instability
- Richtmyer–Meshkov instability
- Mushroom cloud
- Plateau–Rayleigh instability
- Kármán vortex street
- Taylor–Couette flow
- Fluid mechanics
- Fluid dynamics
- Reynolds number
- Turbulence
Notes
- ^ a b Fox, Karen C. (30 December 2014). "NASA's Solar Dynamics Observatory Catches "Surfer" Waves on the Sun". NASA-The Sun-Earth Connection: Heliophysics. NASA.
- ^ Sutherland, Scott (March 23, 2017). "Cloud Atlas leaps into 21st century with 12 new cloud types". The Weather Network. Pelmorex Media. Retrieved 24 March 2017.
- ^ .
- ISSN 0004-637X.
- .
- ISSN 1941-6016.
- .
- S2CID 67827521.
References
- Lord Kelvin (William Thomson)(1871). "Hydrokinetic solutions and observations". Philosophical Magazine. 42: 362–377.
- Hermann von Helmholtz (1868). "Über discontinuierliche Flüssigkeits-Bewegungen [On the discontinuous movements of fluids]". Monatsberichte der Königlichen Preussische Akademie der Wissenschaften zu Berlin. 23: 215–228.
- Article describing discovery of K-H waves in deep ocean: Broad, William J. (April 19, 2010). "In Deep Sea, Waves With a Familiar Curl". New York Times. Retrieved April 23, 2010.
External links
- Hwang, K.-J.; Goldstein; Kuznetsova; Wang; Viñas; Sibeck (2012). "The first in situ observation of Kelvin-Helmholtz waves at high-latitude magnetopause during strongly dawnward interplanetary magnetic field conditions". J. Geophys. Res. 117 (A08233): n/a. hdl:2060/20140009615.
- Giant Tsunami-Shaped Clouds Roll Across Alabama Sky - Natalie Wolchover, Livesciencevia Yahoo.com
- Tsunami Cloud Hits Florida Coastline
- Vortex formation in free jet - YouTube video showing Kelvin Helmholtz waves on the edge of a free jet visualised in a scientific experiment.
- Wave clouds over Christchurch City
- Kelvin-Helmholtz clouds, in Barmouth, Gwynedd, on 18 February 2017