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Can RMS velocity even be smaller than mean velocity?

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Old   May 22, 2012, 22:57
Default Can RMS velocity even be smaller than mean velocity?
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Dear all,

I'm using the mixture, k-e, air-water two phases model in FLUENT to simulate bubble column. I calculated with transient mode.

After calculation, I checked the results: RMS velocity magnitude and mean velocity magnitude. I found out that RMS value is even smaller than mean value. Does anyone know how can it be like this? Is there anything wrong?

Thanks a lot.
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Old   May 23, 2012, 01:17
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Sijal Ahmed Memon (turboenginner@gmail.com)
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It can be. RMS is the root mean square of fluctuating components that is u',v' and w'.
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Old   May 23, 2012, 04:18
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Quote:
Originally Posted by Far View Post
It can be. RMS is the root mean square of fluctuating components that is u',v' and w'.
Thanks for your reply.

I have one more question: is RMS calculated as ((x1^2+x2^2+x3^2+...+xn^2)/n)^0.5?
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Old   May 23, 2012, 04:26
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I guess so.
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Old   May 23, 2012, 04:36
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Some links are shared here, where you can find the discussion about the RMS velocity
Trans. SST Intermittency Factor and Viscosity Ratio
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