# Flow/ Velocity Calculation

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November 19, 2012, 15:49
Flow/ Velocity Calculation
#1
Member

Nikunj Raithatha
Join Date: Jul 2012
Location: Washington DC
Posts: 47
Rep Power: 7
Hello All!

As shown in the attached figure, I have fluid passing in positive and negative direction, through a plane. I was wondering, if there is a way to calculate the average flowrate (or even velocity) that is going in positive direction and negative direction separately.

In paraFoam, I tried using "integrateVariable" filter for this plane, but it is giving me integrated total velocity through this plane and not negative and positive values.

Any help in this regard will be greatly appreciated. Thanks for your time.

Regards,
Nikunj.
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November 21, 2012, 19:19
#2
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Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,020
Rep Power: 43
Quote:
 Originally Posted by Nikunj.R Hello All! As shown in the attached figure, I have fluid passing in positive and negative direction, through a plane. I was wondering, if there is a way to calculate the average flowrate (or even velocity) that is going in positive direction and negative direction separately. In paraFoam, I tried using "integrateVariable" filter for this plane, but it is giving me integrated total velocity through this plane and not negative and positive values. Any help in this regard will be greatly appreciated. Thanks for your time. Regards, Nikunj.
Something like (this is just a sketch, assumes that you're either on a faceSet, faceZone or sampledSurface)

Code:
```variables (
"upArea=sum(U.z>0 ? area() : 0);"
"upVelSum=sum(U.z>0 ? U.z*area() : 0);"
);

expression "upVelSum/max(upArea,1e-15)";```
in swak4Foam could do the trick.
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