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-   -   what is "rms-fluctuation velocity"? (https://www.cfd-online.com/Forums/main/4005-what-rms-fluctuation-velocity.html)

Hai-Wen Ge October 16, 2001 03:59

what is "rms-fluctuation velocity"?
 
Dear All, Who can tell me what's the meaning of "rms-fluctuation velocity"? what's the physical meaning of it? How to compute it? thanks!

Lionel Larcheveque October 16, 2001 05:38

Re: what is "rms-fluctuation velocity"?
 
Hi,

the "rms-fluctuation velocity" is defined as : u'=sqrt{ M(u^2) - [M(u)]^2 }, where M is an average operator (time averaging, and space averaging if there are homogeneous flow directions). From a statistical point of view, this is the standard deviation of the random variable u. From a physical point of view, this may be related to the intensity of the turbulence. For example, the turbulent kinetic energy is classically defined as : k=.5(u'^2+v'^2+w'^2)

best regards


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