Buoyancy frequency (Physics & Chemistry)
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Physics & Chemistry (main)
Buoyancy frequency
March 30, 2010, 12:00 am
October 28, 2011, 4:35 pm
| This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion. |
Buoyancy frequency is the frequency with which a parcel or particle of fluid displaced a small vertical distance from its equilibrium position in a stable environment will oscillate. This concept, also termed the Brunt–Väisälä frequency, can apply to a liquid or gaseous medium. The parcel will oscillate in simple harmonic motion with an angular frequency defined by:
where g is the gravitational acceleration, θ is the potential temperature, α is the thermal expansion coefficient, and β is the saline contraction coefficient. In practice, the equivalent formula:
is often used, where c is the velocity of sound, although care must be taken to consistently evaluate ρ and c.
Further Reading:
- Physical Oceanography Index
- J. S. Turner. Buoyancy Effects in Fluids. Cambridge Univ. Press, 1973.
- Trevor McDougall, Steve Thorpe, and Carl Gibson. Small-scale turbulence and mixing in the ocean: a glossary. In J. Nihoul and B. Jamart, editors, Small-Scale Turbulence and Mixing in the Ocean, pages 3-9. Elsevier, 1987.
