Can RMS velocity even be smaller than mean velocity?
 

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.

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?

I guess so.

Some links are shared here, where you can find the discussion about the RMS velocity
http://www.cfd-online.com/Forums/flu...ity-ratio.html