velocity fluctuations for an unsteady simulation
hi
is there any way in fluent to find velocity fluctuations to calculate turbulence kinetic energy for a transient/unsteady simulation? thanks 
Hi, you are actually talking about DNS of turbulent flow.

No I am performing LES and in post processing i only get an option for sub grid scale turbulence. So i figured out if i have velocity fluctuations i can calculate TKE using equation 1/2(u'^2+v'^2+w'^2) where u',v' and w' are the fluctuating components of the velocity. I also know that i can get fluctuating components by using u'=uubar where u is instanteanous velocty and ubar is the time averaged velocity. I m just not sure how to do it in fluent.

I have 1 idea in mind but not sure if it is correct. So to find velocity fluctuations at a point in the domain...i can turn on the data sampling which will alow me to find average velocity at a specific time and i also have instanteanous velocity at that time, now if i subtract average velocity from the instanteneous velocity am i correct to understand tht i will get fluctuating velocity at tht time at tht point?

if you solve ns eq. like that, you are performing DNS.
non of the turbulent models, including LES, solves for the instantaneous velocity. 
thanks for ur reply. ok i understand wat u mean...but if i want to find mean TKE in LES wat shuld i do n by velocity fluctuations (u', v', w') i meant 'mean' velocity fluctuations. How do i find the fluctuating components of velocity in fluent? sorry if i m bein very confusing, i m confused myself :)

you can use monitor or export during calculation (menu: file > export > ...) to collect transient data.

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