Allow string periodic for periodic BCs

[marchdf]

Summary

Allow string periodic for periodic BCs.

Basically it's weird to get an error message that says:

std::runtime_error: Setting periodic BC on a periodic face xlo is not allowed

Pull request type

Please check the type of change introduced:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Checklist

The following is included:

• new unit-test(s)
• new regression test(s)
• documentation for new capability

This PR was tested by running:

• the unit tests
  • on GPU
  • on CPU
• the regression tests
  • on GPU
  • on CPU

[mbkuhn]

so, the geom.is_periodic still has to be correct, but this now allows the user to put a periodic argument for that boundary face instead of having to remove the boundary face argument. What happens if a user puts periodic for the face but has geom.is_periodic = 0 for that direction?

[marchdf]

the geom.is_periodic still has to be correct, but this now allows the user to put a periodic argument for that boundary face instead of having to remove the boundary face argument.

yes or (currently) it has to be xlo.type = null, which is weird.

What happens if a user puts periodic for the face but has geom.is_periodic = 0 for that direction?

If I do xlo.type=periodic geometry.is_periodic=0 1 0 then it aborts with:

Invalid BC specification for non-periodic boundary = periodic

[mbkuhn]

works for me!