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Old   August 17, 2005, 10:36
Default BC Problem - internal
Ralf Schmidt
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I have a geometry with several faces inside the fluid volume for reporting e.g. velocities to compare with experimental data.

In Gambit I defined them all as "Internal" BC. But when I am importing the mesh into Fluent, there are two of them that are automatically transformed into walls (when building grid: "Cannot change 11_y0800 to interior because there is only one adjacent cell threat")

What is the problem? The face has a volume on both sides, as like the others. Both faces are defined in Gambit the same way like the others. Is there maybe a maximum number of internal BC that can be handled in Fluent?

Thanks for your answers in advance,

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Old   August 17, 2005, 10:48
Default Re: BC Problem - internal
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This usually means that the faces aren't connected to both volumes. Check to make sure there is only one face where each of these internal BC's lay. If this is the problem, a "wall" BC (where "wall" is the default name given by fluent to un-defined BCs) should have also been created for the coincident faces (since there's two volumes, there are two faces, unless they've been connected, so each face will have it's own BC). If there are two faces, then you can manually connect them in Gambit (and then you'll have to fix your mesh, fix your BC and re-export the mesh).

Also, make sure that you selected the correct faces when defining your internal BCs (if you grabbed a face that should actually be part of another wall or something, then this would explain the error as well).

If neither of those fix the problem, then how did you create the internal faces?

I've never heard of any limit on internal BCs, so I don't think that's the problem.

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Old   August 18, 2005, 03:34
Default you are right!
Ralf Schmidt
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Hi, thanks for your answer. It seems, when I created the geometry, I subtract one volume from the other. Because I retained the subtracted volume, Gambit created a new face and I didn't noticed. Now everything is fixed! Ralf

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