Re: [Libmesh-users] Periodic boundaries for circular segment domains

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

On Wed, 28 Feb 2018, David Knezevic wrote:

> I would like to implement a periodic boundary condition on a model with
> circular symmetry, e.g. solve on sector of a disk with periodicity. To
> implement this it seems like all I'd need to do is subclass
> PeriodicBoundary and override get_corresponding_pos() to impose the
> appropriate rotation rather than just a translation, and then add the
> PeriodicBoundary subclass object to the system in the usual way. Is that
> indeed all that's required,

Yes, if it's working correctly!

> or would we need something more?

If you have something vector or tensor valued, like e.g. a *velocity*
variable, and your formulation doesn't already use polar coordinates
for the components of that variable, then you're in trouble if you
want anything other than 0/90/180/270 degree rotations, because we
don't currently have any way to specify a periodic BC for one variable
as a weighted sum of other variables.

> Has anyone tried this case before?

We actually have some CI coverage for it thanks to the MOOSE guys:
tests/bcs/periodic/orthogonal_pbc_on_square.i
---
Roy