Learning Forum

[zoelle.wong]

I have experience with creating a periodic boundary conidtions, but I've never seen this issue before: Non-Intersected faces found for matching interface periodic-walls! Please improve the alignment of interface zones!

The off-set was automatically set; how can I check the off-set for my current setup? The walls that I'm specifying as periodic are in the second screenshot below. Thank you!

 

[Rob]

Check what's set in Mesh Interfaces and also under Periodic in the Boundary Conditions menu. 

[zoelle.wong]

I used the "auto" off set and ANSYS automatically computed -5deg. What can I do in the mesh to improve the offset?

[Rob]

5 degrees? Can you confirm as the image looks a little larger than that. 

[zoelle.wong]

 

my thought process is that the offset is largely due to my mesh being a volumetric, unstructured mesh (as seen by the the 2 periodic BC interfaces in image)

[Rob]

That's right, but the angle looks closer to 90 degrees. 

[zoelle.wong]

ah i see- the angle between the two faces are 90deg. should i change the mesh such that the angle between the two faces is 180deg?

[Rob]

No, 90 degrees is generally a good angle - you've reduced the cell count but not created a sharp angle at the axis. It's the right choice in many cases....  The solver is usually very good at the calculation. Can you set the fluid rotation reference (axis) to x (default is z) and recalculate? I'm wondering if that's an issue. 

[zoelle.wong]

For the solver, i set it to be an auto conformal, origin at (0,0,0),  axis of rotation (1,0,0,), and the auto-offset was calculated as -5deg. I think the offset might be too large; I did manuall decrease the offset at different angles less than 5deg but then the periodic BC wasn't built 

[Rob]

The offset should be equal to the angle between the two periodic boundaries. 

[zoelle.wong]

thank you that worked! changing the offset to 90deg fixed the issue. lastly- how can i check the periodic BCs are being enforced correctly? there's a way for me to "mirror" the blocks but would that be showing the mirrored BCs or projecting the flow field results as a mirror image? 

[Rob]

Don't mirror, use Periodic Instancing from the ribbon. Display tab. It's changed since I last looked at the function too.