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-   -   Using potentialFoam with simpleBuoyantFoam (http://www.cfd-online.com/Forums/openfoam-solving/59513-using-potentialfoam-simplebuoyantfoam.html)

lasb August 10, 2007 05:12

Hi, I am trying to use the
 
Hi,

I am trying to use the simpleBouyantFoam solver with inlets and outlets.

The problem is that it is complaining over a continuity error in the outflow.

--> FOAM FATAL ERROR : Continuity error cannot be removed by adjusting the outflow.

Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.

Total flux : 76.8043
Specified mass inflow : 10.4276
Specified mass outflow : 0
Adjustable mass outflow : 1.17153e-16


From function adjustPhi(surfaceScalarField& phi, const volVectorField& U,const volScalarField& p
in file cfdTools/general/adjustPhi/adjustPhi.C at line 111.

FOAM exiting

So I tried to look at my boundaryconditions. They seem fine. Then I looked at potentialFoam. My problem is that if I want to initialise the outflow. p is calculated as p/rho. That is: the dimensions for p are not the same in potentialFoam as they are in bouyantSimpleFoam.

If someone has any ideas how to solve/omit this problem I would be very happy.

Best Regards,
Lasse

hjasak August 10, 2007 05:22

Yes: take the same geometry, s
 
Yes: take the same geometry, solve potential flow separately and copy ONLY the velocity field.

Alternatively (I take it you've got zeroGradient on U at outlet), set the initial field to something that is non-zero and try again.

Please let me know what happens, I'm interested if I'm guessing right.

Hrv

lasb August 10, 2007 07:27

Hi, Thanks for replying so
 
Hi,

Thanks for replying so fast.

You were right. If I run potentialFoam and then copy the velocity field and run it with buoyantSimpleFoam it works. But it can only run for a limited amount of time, then it says:

--> FOAM FATAL ERROR : Maximum number of iterations exceeded

I can see that it is crashing trying to calculate pd. I'm not sure how to solve this.

Any ideas?

Lasse

hjasak August 10, 2007 07:49

The solver itself is not limit
 
The solver itself is not limited in any way: there is no question of the solver running to a limited amount of time or any similar dishonesty.

I bet it is failing when trying to calculate some material properties as a function of temperature and pressure using Janaf. Try using constant material properties - it should run without trouble. Onc eyou get that sorted out, switch back to Janaf and see what happens.

Enjoy,

Hrv

lasb August 10, 2007 08:31

Thanks, I bet you're right.
 
Thanks, I bet you're right.

I'm still learning OpenFOAM and has no idea where I can find material properties nor how to switch them on and off. Where do I do that?

I don't know what Janaf is, but I guess it's not that important.

Sorry for my stupid questions.

Lasse


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