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-   -   PotentialFOam (http://www.cfd-online.com/Forums/openfoam-solving/109434-potentialfoam.html)

sampathevs November 17, 2012 13:47

PotentialFOam
 
Im continuously getting this error when Im running potentialFOam


continuity error = 9.077995892e-08
Interpolated U error = 1.798108527e-05


--> FOAM FATAL ERROR:
No valid model for viscous stress calculation.

From function forces::devRhoReff()
in file forces/forces.C at line 113.

FOAM exiting

its running, but in the last Im getting this . What does this mean? and wil this affect simpleFOAM?

masoudsh June 20, 2016 16:04

Hi

I have this error too,can anybody help me?
It's about adding forces code in controldict.

"--> FOAM FATAL ERROR:
No valid model for viscous stress calculation."


thanks
masoud

Kina June 21, 2016 04:30

That is actually not a problem. It is because potentialFoam cannot calculate the forces calculated in the controlDict functions. You can either ignore the message or simply run potentialFoam the following way.

Code:

potentialFoam -noFunctionObjects
Cheers
Alex

masoudsh June 21, 2016 07:16

Hello Alex

thanks by your answer.
I use "-noFunctionObjects" but this command overrides the function added in controldict,and I don't want to do that.
I want to calculate forces and forces coefficeint SO I added some commands in controldict.
Can you help me?

Best Regards
Masoud

matthewshorter June 21, 2016 08:41

Hello. PotentialFoam solves the inviscid incompressible equations and gives you what is effectively the analytical solution. According to the D'Alembert paradox, the drag on any object in the potential flow field will be 0. The lift may be non zero, but I don't think controlDict is the way to find that- look into using paraView or something other postprocessing tool for that.

masoudsh June 21, 2016 10:32

Hello Matthew

thanks for your reply
I use twophaseEulerfoam
and I have this error too.

"--> FOAM FATAL ERROR:
No valid model for viscous stress calculation."


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