Julian Andrej

This boundary condition does not directly follow just by closing the pressure poisson with a Neumann boundary condition. I'll point to the Nek5000 refrence again. Citing > The open(outflow) boundary...

@wsmoses this came up in an internal discussion and we'd appreciate a slim repo as well.

If you want to keep this branch as a testbed, sure.

> Something is not right with this branch. Currently I see 1320 commits and 1037 files changed. > > Was this branch re-based at some point but then the old...

ping @nnpp-schneier @victor-decaria-nnl

https://github.com/mfem/mfem/blob/9343ffad7b64de9ccf29ad23c740bb02d916c3e1/mesh/submesh/submesh.cpp#L71-L72 We inherit the elements boundary attribute that belongs to the submesh. How can an element have multiple attributes?

Thanks for your detailed description. Is Boundary attribute 3 of the original mesh the last overwritten state s.t. submesh takes the last state in the figure below? 

Adding a MFE which used to work in the original PR for the C++ interface https://fwd.gymni.ch/nsKPWF

@GregTheMadMonk did you check the output values? I only get zeros from the fwddiff in your branch. edit: Just understood your comment now. I hope you find the problem, I'm...

Have you ran `ExchangeFaceNbrData` on the space before you call `GetFaceNbrFE`?