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interFoam channel hull parasitic currents?

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Old   May 27, 2014, 05:43
Default interFoam channel hull parasitic currents?
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Mirco Brunke
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Hi Foamers,

this is my first post and i'm not sure if it is at the right place... and not so good in writing englisch... But my problem is:

I use interFoam with OpenFoam 2.3. The case is a wind tunnel with two phases and a geometrie inside. Boundary conditions and all other settings are like the tutorial DTCHull in interDyMFoam but without moving mesh. There are only some changes at the velocity. It starts with 0 m/s and then speed up with 0.3m/s² for the whole area.

The result shows, everywhere where the grid split into smaller cells are non-physical velocities near the surface in the air phase. The picture shows a sitution like this. This is the result after 0.1 seconds. So the velocity should be 0.03m/s.

Is here anybody who knows what I did wrong or are these parasitic currents? Is there a trick to handle this problem?

I changed a little bit the interFoam solver after seeing these results. But only at the pEqn.H like some people wrote here in the Forum for parasitic currents (Brackbill or Raeini). But I didn't test the complete code of Raeini. This changing had no effect.


Greetings,
Mock
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Old   June 8, 2014, 09:27
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Bruno Santos
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Greetings Mock and welcome to the forum!

It looks to me that the mesh transition is in a very bad place. Have a look into this blog post of mine, so that you can get a better idea on how important the mesh is, specially "Case two": OpenFOAM: Interesting cases of bad meshes and bad initial conditions

Best regards,
Bruno
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Old   August 9, 2014, 22:23
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Santiago Marquez Damian
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Hi, do you see these spikes at interphases?

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Old   August 11, 2014, 03:15
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Hi santiagomarquezd,

these spikes are at the air-phase. Maybe a these pictures show it better:

ErrorOverview.jpg

ErrorOverview1s.jpg

The red oval shows the location from the upper part of the picture (xz-plane).

Best regards,

Mock

Last edited by Mock; August 11, 2014 at 06:05.
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Old   August 14, 2014, 18:26
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Santiago Marquez Damian
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As Bruno said, probably mesh problems.

Regards.
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