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Blowing up epsilon using wall BC interfoam

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Old   May 12, 2017, 18:14
Default Blowing up epsilon using wall BC interfoam
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Jose
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Hello FOAM users

Currently I'm facing some difficulties in the solution of a simple case of a 3d rectangular duct spillway simulation. I am using interFoam with an initial volume of fluid after running the setFields utility. I have run the case with the following BC:

The results are OK when defining the side walls as symmetry but if I turn them into a wall BC, the bounds for epsilon after 1/3 of the simulation time (30s) blows up and the automatic adjusted timestep get as low as 1e-34. I have done a bigger model in the Y direction and also I have done a more refined mesh, in order to see if the thin model is the cause of the problem, but I'm still having the same error in the execution when changing the symmetry BC to wall BC. Does anybody have any idea of this behavior?

Thanks in advance
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Old   May 13, 2017, 02:04
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Uwe Pilz
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If your image shows the actual geometry: You have only 2 cells in spanwise direction. Every cell has to fulfill a b.c. then. I recommend to use more cells, at least 6, better 8.
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Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)
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Old   May 14, 2017, 21:47
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Thank you for your response Mr. Pilz
I have run other geometries longer in the spanwise direction and also with dense meshes, about 100 divisions in the spanwise direction, and I keep having trouble in the solution. Epsilon keeps blowing up and the timestep getting small on each iteration.
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Old   May 15, 2017, 01:39
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May you provide an example, for I may look at the case by myself? Of course I prefer a simple one, which shows the effect.
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