# Is negative turbulence intensity right?

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 April 18, 2006, 10:00 Is negative turbulence intensity right? #1 Oliveir Guest   Posts: n/a Hi all.... I have doubt about definition of turbulence intensity when I try to compare CFD turbulence profile with my experiment. TI= u'_RMS(x)/U_mean(x) Should I take absolute value of U_mean(x) while calculating U_mean(x)? CFD shows reverse flow (negative velocity) at some locations. Thanks for help.

 April 18, 2006, 10:35 Re: Is negative turbulence intensity right? #2 Jonas Larsson Guest   Posts: n/a Turbulence inensity is always positive. You should take the absolute value of the mean flow velocity. Check out the CFD-Wiki page on turbulence intensity for a more comprehensive definition. You can find it here: http://www.cfd-online.com/Wiki/Turbulence_intensity

 April 18, 2006, 12:33 Re: Is negative turbulence intensity right? #3 opaque Guest   Posts: n/a Jonas is correct, but I rather say (like in the Wiki information that Jonas added recently) that you should take the speed or norm of the transient averaged velocity vector, i.e. U . Absolute value of a vector is a generalization and may confuse those not used to it.. I rather say the norm of the velocity vector or speed. good luck, Opaque.

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