Face data and restart for new staggered
In the old staggered implementation, it was possible to write out face data (velocities) as points to a .vtp file.
This file could then be used for restarting simulations.
Visualizing and analyzing these point-wise face velocities in ParaView is rather cumbersome, so I introduced an IntersectionWriter for the new staggered such that the element edges actually appear graphically (looks like the Surface With Edges representation in ParaView).
However, this class seems overly complicated and furthermore, interior edges always appear twice (one intersection per element). The latter point may make it difficult to use the resulting .vtp files for restarting a simulation, unless we also always write out the dofIdx, too.
How should we proceed here?
(a) Stick to the "old" point-wise solution?
(b) Further improve the intersection writer such that it can also be used within our VTKOutputModule?
(c) Write out .vtp files manually (as done with the points), where the element edges are treated as 2d/1d elements
I guess (c) would be the most readable solution. One could try to figure out the element connectivity stuff for VTK "manually" (don't know yet how complicated that is) or one could use FoamGrid which would make the implementation really simple (at the cost of
an additional dependency).