Momentum flux: Difference between revisions
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<div class="definition"><div class="short_definition">The vertical [[flux]] of horizontal [[momentum]], equal to the force per unit area, or [[stress]].</div><br/> <div class="paragraph">The [[Reynolds stress]] (τ<sub>''R''</sub>) can be determined from the [[covariance]] of the fluctuations of the horizontal (''u''′, ''v''′) and vertical (''w''′) [[wind]] components, by <div class="display-formula"><blockquote>[[File:ams2001glos-Me28.gif|link=|center|ams2001glos-Me28]]</blockquote></div> where ρ is air density. A direct measurement is possible with eddy-correlation techniques, or an indirect determination can be made using [[Monin–Obukhov similarity]] flux-profile relationships (<br/>''also called'' [[universal functions]]). The relation between the [[velocity]] scale ([[friction velocity]] ''u''<sub>*</sub>) and the momentum flux is <div class="display-formula"><blockquote>[[File:ams2001glos-Me29.gif|link=|center|ams2001glos-Me29]]</blockquote></div> Momentum flux can be associated with either [[mean velocity]] components, internal [[gravity waves]], or with turbulent velocity fluctuations. For [[turbulence]], the momentum flux is also called the Reynolds stress. For waves, it is related to [[mountain wave]] drag.</div><br/> </div> | <div class="definition"><div class="short_definition">The vertical [[flux]] of horizontal [[momentum]], equal to the force per unit area, or [[stress]].</div><br/> <div class="paragraph">The [[Reynolds stresses|Reynolds stress]] (τ<sub>''R''</sub>) can be determined from the [[covariance]] of the fluctuations of the horizontal (''u''′, ''v''′) and vertical (''w''′) [[wind]] components, by <div class="display-formula"><blockquote>[[File:ams2001glos-Me28.gif|link=|center|ams2001glos-Me28]]</blockquote></div> where ρ is air density. A direct measurement is possible with eddy-correlation techniques, or an indirect determination can be made using [[Monin–Obukhov similarity theory|Monin–Obukhov similarity]] flux-profile relationships (<br/>''also called'' [[universal functions]]). The relation between the [[velocity]] scale ([[friction velocity]] ''u''<sub>*</sub>) and the momentum flux is <div class="display-formula"><blockquote>[[File:ams2001glos-Me29.gif|link=|center|ams2001glos-Me29]]</blockquote></div> Momentum flux can be associated with either [[mean velocity]] components, internal [[gravity waves]], or with turbulent velocity fluctuations. For [[turbulence]], the momentum flux is also called the Reynolds stress. For waves, it is related to [[mountain wave]] drag.</div><br/> </div> | ||
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Latest revision as of 16:27, 25 April 2012
momentum flux
The Reynolds stress (τR) can be determined from the covariance of the fluctuations of the horizontal (u′, v′) and vertical (w′) wind components, by where ρ is air density. A direct measurement is possible with eddy-correlation techniques, or an indirect determination can be made using Monin–Obukhov similarity flux-profile relationships (
also called universal functions). The relation between the velocity scale (friction velocity u*) and the momentum flux is Momentum flux can be associated with either mean velocity components, internal gravity waves, or with turbulent velocity fluctuations. For turbulence, the momentum flux is also called the Reynolds stress. For waves, it is related to mountain wave drag.
also called universal functions). The relation between the velocity scale (friction velocity u*) and the momentum flux is
