Periodic boundary condition with free slip wall
 

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

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.

Periodic boundary condtion
 

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

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.