Periodic cube mesh

The preferred way is to use names instead of numbers.
If you don't have names, you can create a region from a BitArray, like

Region(mesh,BND, BitArray([True,False,False,True]))

This region is defined on the first and last boundary.

Thank you, Joachim!

How can I use this region in, for example, "definedon=mesh.Boundaries(...)"?
Is it possible to assign names to regions?

Best, Philipp

You can set boundary names on a Netgen mesh with
mesh.SetBCName(index, name)
BC indices are 1 based.

Thank you, Christopher!

In the attached script, I tried to do it this way.
However, I always get the following error:
Can you tell me what I am doing wrong?

Thanks for your help.

Best, Philipp

This is a bit messy... A quickfix is to set names for all boundary conditions. I will discuss a nice solution with Joachim when he's back in Vienna.
Best
Christopher