ENH: automatic leak closure

Functionality to add/problem to solve

snappyHexMesh has provision for specifying external, i.e. non-meshed locations. If any part of the resulting mesh connects an inside location to an outside one the meshing stops. It would be nice to automatically close 'small' gaps and continue instead.

Proposal

A topological hole detection algorithm might be good enough. These walk on the initial mesh and attempt to close any 'leaks' in it. Another approach would be to actually 'correct' the input geometry but that would be much more problematic.

What does success look like, and how can we measure that?

Initially just create a castellated, closed mesh. See how it behaves during snapping and layer generation.

Links / references

"A 3D-Hole Closing Algorithm", Zouina Aktouf et al