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-   -   Prob in rms velocity components, pls help.. (https://www.cfd-online.com/Forums/cfx/111350-prob-rms-velocity-components-pls-help.html)

sakurabogoda January 4, 2013 08:39

Prob in rms velocity components, pls help..
 
I am using CFX Post and there when I want to get axial, tangential and radial velocity components I have to go to Trubo mode and specify the rotational axis and then do the “calculate velocity components”.

But my problem is,

01. When I need rms values of each component how can I obtain them? (I need to plot them in a chart)

I used “Transient Statistics” in CFX Pre and inserted max, min and rms for velocity.

02. But in CFX-post why I cannot find these variables?

I am very glad if someone can help me to solve my issues.

sakurabogoda January 10, 2013 09:49

Anybody can help me????

If I input a variable in CFX Post for rms tangential velocity, is it correct?

rms tanV= sqrt(Velocity.Circumferential^2)

I concern is whether Velocity.Circumferential is a fluctuating velocity or not?

Does anyone has experienced in this????????????

Possa January 10, 2013 15:26

Hello,

To be able to plot residuals (RMS, MAX) in CFX-Post you have to do the following in the CFX-Pre:
- Check the box "Output Equations Residuals" and "All" under the Trn Results tab in the Output control. Do the same in the Results tab also in the Output control.
When this definition file runs in the solver it will record residuals and then you can visualize them in the Post.

Regards,
Possa.

sakurabogoda January 15, 2013 22:39

Finally found it.. very simple.
When specify rms velocity in transient statistics, all rms velocity values for axial, tangential and radial can be visualize in Post.
I couldn't see it as I did steady state analysis and not transient i think. :)

Mina_Shahi February 13, 2013 09:13

Quote:

Originally Posted by sakurabogoda (Post 402072)
Finally found it.. very simple.
When specify rms velocity in transient statistics, all rms velocity values for axial, tangential and radial can be visualize in Post.
I couldn't see it as I did steady state analysis and not transient i think. :)

Hi

I also need to plot rms value of the stream wise velocity fluctuation in my fluid domain(√(u' u' )) .
since before running the transient case i specify velocity in the transinet statistics. so in my variables i have velocity correlation uu.Trnavg.
is that sqrt(velocity correlation uu) representing (√(u' u' )) ?

sakurabogoda February 13, 2013 22:30

Hi Mina,

Trnavg is arithmetic avg of velocity, you can define sqrt of U in transient statistics and then you can see Trnrms in CFX Post variable list.


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