ex04 broken without InterfaceMesh1D

Following 078fd379cc550976ab6264feed6a44767de48afc for #195, `python docs/examples/ex04.py

NameError: name 'InterfaceMesh1D' is not defined

[kinnala]

I’ve started again to work with these mortar methods so I’ll probably create better support at some point. I’d like to also cover 3D cases but it’s going to be much trickier to match elements over the interface.

[gdmcbain]

O. K., thanks, that makes sense.

That’s a whole new thing then. I don’t think there is any smooth geometry in the library thus far?

But one must be careful to not make any assumptions that are not true in the general case.

Indeed.

Actually though I imagine (without having tried it) that it should be possible to handle the conforming case (in two or three dimensions, maybe even also in one?) without modification to the library, just by defining an entry in the Mesh.boundaries attribute along the interface and then a FacetBasis there and treating the subdomains separately as in ex26. So that might not get in the way of a future implementation for curved nonconformal interfaces. I’m not working on conjugate heat transfer right at the moment but will doubtless return to it sooner or later and will probably look at segregrated versus monolithic solution (with conformal interface) then. I might also get to fluid–solid interaction one day.