Facet orientation code in interior facet assembly is disabled

[Martin Sandve Alnæs]

In Assembler.cpp, assemble_interior_facets, the call to facet->adjacent_cells is disabled. This seems to be something related to getting interior facets working in parallel? Can it now be enabled again?

[Martin Sandve Alnæs]

@chris_richardson @garth-wells know anything about this?

[Prof Garth Wells]

I'll take a look, but I suspect that it's no longer required since the addition of ghosted meshes.

Interior facet integrals are working (in serial, and since recently also in parallel).

[Anders Logg (Chalmers)]

Another related issue is support for facet orientation in SystemAssembler. As far as I know, this has never been supported (only in Assembler).

[Chris Richardson]

What happens now when you ask for an interior facet integral in parallel without setting ghost_mode? I tried, and got:

*** Error:   Unable to complete call to function build().
*** Reason:  Assertion facet->is_ghost() failed.

which is not very informative...

[Martin Sandve Alnæs]

It is required, it is a feature to enable specifying what is the + and - sides of each facet in interior facet integrals.

The array with somewhat misleading name "facet_orientation" contains the cell number that is to be cell 0 (which is cell + if I recall correctly).

There may be a more intuitive way to specify it though, but it is a needed feature for asymmetric interior facet integrals where + and - matters.

[Martin Sandve Alnæs]

https://bitbucket.org/fenics-project/dolfin/pull-request/199/remove-facet_orientation-and-make-ds-pick/diff#comment-4710398

[Martin Sandve Alnæs]

I've pushed but need a reminder to self to add the docstring:

If cell_domains is provided, the '+' and '-' sides are chosen such that the cell_domains value in the cell at the '+' side cell is larger than the cell_domains value in the cell at the '-' side cell. If the values are equal or the cell_domains are not provided, the sides are chosen arbitrarily.

[Martin Sandve Alnæs]

Removing milestone: 1.6 (automated comment)