[morteza08]

Dear Friends

I have modelled a 3d pipe in Gambit and Fluent.
To validate the results I have to calculate the friction factor in the pipe.
There are so many threads in cfd-online , but there is not any satisfying response.
I read in a tutorial that I have to calculate the friction factor using the below formula:

f=(8*shear stress)/(density* average velocity^2)

But, the question is here, how can I calculate the mean velocity?
in which plane i have to calculate that?
and how to calculate the shear stress?



the pipe diameter : 0.12m
velocity : 12.17 m/s along negative z

Please read the attached file.


thank you in advance
Morteza


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