> On 7 Nov 2018, at 14:23, Floriane Gidel [RPG] <mmfg@leeds.ac.uk> wrote:
>
> Hi Lawrence,
>
> I need a way to distinguish the two subdomains, that are 1) the disk, 2) the square with a hole instead of the disk (see black and blue meshes in the attached figure).
> Can I make the equivalent to the blue mesh (i.e., a square with a hole) using PeriodicUnitSquareMesh ? And if so, can I make sure that the nodes at the boundary of my disk mesh (black) match those of the plane mesh (blue) at the hole boundary?

Ah, that's the bit I was missing. With periodic unit square mesh it is not possible. One could hack something that moved the mesh nodes around to capture the circle appropriately. But that's going to be fiddly too.

Cheers,
Lawrence