[MOAB-dev] exchange tags over interface entities

[Lorenzo Alessio Botti]

> 1. Take state vector X, residual vector F (starts empty)
> 2. Evaluate X onto local interface quadrature points QX (your ghost Vec).
> 3. Gather parts of QX to owner of each quadrature point.
> 4. Solve Riemann problems at owned interface quadrature points to produce interface fluxes QF.
> 5. Broadcast QF from owner to ghoster.
> 6. (perhaps concurrently with above) evaluate interior and use fluxes QF when they arrive.


My strategy is different.
Since I know that I have to evaluate QX at each non-linear iteration instead of communicating QX
I communicate the shape function evaluations on partition interfaces, say SX, once and for all (as soon as the mesh doesn't change).
So at each iteration I just have to communicate the dofs for each ghost element and I'm able to compute
QX. I do the same for derivatives, I communicate once and for all SDX and evaluate QDX using the dofs.
I assemble both the matrix and the rhs, possibly at the same time to avoid redundant flux evaluations.
Do you think that this is suboptimal?

Lorenzo