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PdRefCell and pdRefValue in InterFoam

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Old   November 10, 2008, 21:30
Default Hi there I want to run interF
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Sara Schairer
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Hi there
I want to run interFoam. I get as an error message: keyword pdRefCell is undefined in dictionary...
When I add pdRefCell in fvSolutions the next error message is about the missing keyword pdRefValue.
What do these values mean and why do I need them? The damBreak tutorial doesn't need them.
Even when I add both keywords and set them to 1 just to give it a try I get another error message saying:
Continuity error cannot be removed by adjusting the outflow.
But my velocity boundary conditions look alright - at least to me.
What else could I change? Any ideas?
Thanks, Sara
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Old   November 11, 2008, 00:36
Default Hi Sara, you need pdRefValu
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Christian Winkler
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Hi Sara,

you need pdRefValue because interFoam uses a pressure difference relative to a reference pressure. So you should set pdRefValue to, lets say, 100000 (=1bar). Setting it to 1 results in a nearly perfect vacuum....;-)

Best regards from Stuttgart
Christian
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Old   November 11, 2008, 02:13
Default http://www.cfd-online.com/Open
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Sara Schairer
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Danke
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Old   November 11, 2008, 07:07
Default Hi Christian, my question
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Nikolaos Spyrou
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Hi Christian,

my question might sound stupid but I'm confused by your answer. When talking about incompressible flows the typical sentense im my mind is "the absolute pressure level does not matter, only relative pressure is important".

So please tell me what effectively happens when sara changes the pdRefValue from 1 to 100000?

Niko
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Old   November 11, 2008, 07:53
Default Hi Nikolaos, hmm, no stupid
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Christian Winkler
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Hi Nikolaos,

hmm, no stupid question at all. I should refrain from answering question at 5:30 in the morning.

Actually you are right with your statement "the absolute pressure level does not matter, only relative pressure is important".

I think compressible most of the time.....

So back to Saras question:

The error "Continuity error cannot be removed by adjusting the outflow." comes from "adjustPhi.C".
@Sara: I suppose you have a problem with your boundary conditions.

Also have a look at http://www.cfd-online.com/OpenFOAM_D...tml?1130471352

Sorry for the confusion
Best regards
Christian
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