L2Projection does not work accurately for mixed grids

[kimauth]

For mixed grids, the L2Projection can only handle one cell type at a time. So e.g. for a grid composed of triangular and quadrilateral elements, we can do a projection within the triangular elements and another (independent) projection within the quadrilateral elements. But if we have a field that lives on both element types, we would want to do one projection of the field onto all nodes. I'll leave this issue a reminder to implement that (and a warning in case someone uses it for mixed grids).

[termi-official]

Just to discuss it here openly: Wouldn't it be benificial to solve this issue in another way, as we discussed earlier over zoom, i.e. by trying to provide a unified iteration interface over different types of elements (opposing the current state of separating the iteration over different types of elements)?

[kimauth]

Possibly, but I would say that's rather a conceptual question how to handle mixed grids in general. (Or am I misunderstanding you?)

It is possible to fix the L2Projection of fields on mixed grids with the current approach (by the MixedDofHandler) - I just can't implement it right now, thus the reminder.

[fredrikekre]

@kimauth this is resolved right?

[KnutAM]

#949