Re: [Libmesh-users] Periodic BC with adaptive mesh

[Roy S. <roy...@ic...>]

On Thu, 19 Aug 2010, Minq Q wrote:

> I am having a problem when using the periodic BC together with the mesh
> refinement. When one BC is set to refine, the other paired BC is not
> allocated the new nodes as it should.

That's actually correct - the new node is a hanging node on one side
of the boundary, and shouldn't exist on the other until the element on
the other side is refined.

> The strange thing is: The first time of the refinement is OK. But
> from the second time the two paired BCs are become different.

There are currently two issues with combining the periodic BC and the
AMR feature:

The "level 1 conformity" constraint is not supported across the
boundary.  I.e. if you set enforce_level_one to true it will only be
enforced on the mesh interior, not from one side of a periodic
boundary to another.

The mix of AMR and periodic constraint equations may not be working
correctly.  The two features are supposed to be compatible, but when I
wrote the latter I was mostly using one or the other, or at best
running periodic problems where the non-uniform refinement occurred
away from the periodic BC, so I haven't tested it thoroughly.  If you
can set up a test case (as simple as possible, please) where the
constraints are coming out wrong, please post the code to the list,
and we can at least see if it's a simple bug/fix.
---
Roy