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Periodic boundary condition with free slip wall

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Old   March 13, 2017, 05:08
Smile Periodic boundary condition with free slip wall
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Kailash
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Hi all,
I have used a periodic boundary condition for opposite walls of a square channel. These walls are free slip walls because the geometry assumed is a part of the actual flow volume. The simulation is diverging. Is it because the slip walls try to get the extrapolated velocities of the adjacent cell layer and at the same time try to get the same conditions of the opposite wall ( the periodic wall) and is the concept of using these two conditions wrong?


Thank You in advance

With Regards,
Kailash
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Old   March 13, 2017, 10:20
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No, when you create an interface at runtime the faces from the boundary are put into the interface. You can see how well this holds by going to tools > representations > volume mesh > region > boundaries and see how many faces are in each surface.

Your problem is likely elsewhere.
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Old   March 15, 2017, 03:25
Default Periodic boundary condtion
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Kailash
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Thank you. I would also like to know if the mesh at the corners in the attached picture is conformed enough. At the corners there are a few prism layer cells. can they possibly cause the problem ?

Thank you in advance
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File Type: jpg GPF_poly_non_porous_periodic_Mesh Scene 1.jpg (103.2 KB, 6 views)
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Old   March 15, 2017, 20:59
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They could cause a problem depending on the physics. For these types of interfaces it's better to move the interface further into the smaller channel, which prevents the prisms from collapsing.
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