Astrophysics (index)

Brunt-Väisälä Frequency

(Buoyancy Frequency)
(natural frequency of buoyancy waves)

The Brunt-Väisälä Frequency (or Buoyancy Frequency) is a characteristic frequency of buoyancy waves in a stratified fluid, specifically the frequency of the oscillation caused by a vertical displacement of a parcel of fluid within a still body of fluid whose density varies with depth, lying stably within a gravitational field. The concept is used in meteorology and other sciences and applies to stars and planet Atmospheres. It is defined as:

N2 = -(g/ρ0) ∂ρ/∂z
  • N - Brunt-Väisälä frequency.
  • z - depth.
  • ρ - density of the fluid (a function of z).
  • ρ0 - density at the point of disturbance.
  • g - gravitational constant.

(atmosphere,fluid dynamics)
http://en.wikipedia.org/wiki/Brunt-Vaisala_frequency

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