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Why no-slip b.c. does not obtain zero-velocity contour?

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Old   May 15, 2017, 13:14
Default Why no-slip b.c. does not obtain zero-velocity contour?
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Ran
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Greeting O.F.er:

I have a question regarding with no-slip boundary condition.

The simulation case is really simple: flow over a circular cylinder. My confusion is that why velocity contour on the surface of the cylinder is not zero? Is that violate the no-slip b.c?

I am using pisoFoam with O.F. v4.1. ParaView is v5.2.0.

Can someone elaborate a little bit of it?

Thanks,

Ran



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Old   May 16, 2017, 12:46
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Joachim Herb
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You selected the point values of U to be displayed. What happens if you select the cell values (in the menu at the top select U with a box in front of it and not a point).
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Old   May 16, 2017, 16:20
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Ran
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Hi, jherb:

Thanks for your reply.

I have also checked the cell value, but it still gives me zero velocity contour on the surface of the cylinder. Is that something wrong with my understanding of the boundary condition? or it is a bug?

q22.jpg
q11.jpg

Last edited by random_ran; May 16, 2017 at 16:22. Reason: typo
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Old   May 16, 2017, 18:03
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Tobias Holzmann
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The problem should be related to the reader. You are using paraview and not paraFoam, right? So paraview cannot handle the BC. Either use paraFoam or check out the files in your time directories. If for the BC you have »noSlip« and no other value, you are fine and it is really just a problem with displaying the stuff.

A workaround is to rename noSlip to fixedValue. Maybe in the latest ParaView version they fixed it.
Maybe you also can load an empty file named *.OpenFOAM
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Old   May 25, 2017, 08:49
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Wagner C. Galuppo
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Thanks for the answer

I also experienced that this is a dummy exhibit in ParaView. I tried to view the results with the paraFoam -builtin command usage, to check the solution while it was running, and I've got values for the velocity field on the wall. So when I reconstructed it and just checked the results with the paraFoam command, the velocity values for the wall were correct with value zero as expected for a wall with no slip condition. A figure is attached!

Best regards,
Wagner Galuppo

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