dolfin team mailing list archive

[Harish Narayanan <harish.mlists@xxxxxxxxx>]

On 2/17/10 3:44 PM, Anders Logg wrote:
> It is now possible to specify the direction of interior facets such
> that one may know which side of a facet is ('+') and which side is
> ('-').
> 
> To use this, attach a MeshFunction over the facets that specifies for
> each facet which cell (by the cell index) that is the first ('+') side
> of the cell:
> 
>   MeshFunction<uint>* facet_orientation = mesh.data().create_mesh_function("facet orientation");
> 
> Then just fill in the appropriate values in facet_orientation.
> 
> This is useful for integration over facets where the two sides are not
> treated symmetrically, for example using upwinding or in multiphysics
> problems with an interior boundary cutting through the mesh.

I am trying to use this (from Python) and it is not clear to me how this
works.

I do:

orientation = mesh.data().mesh_function("facet orientation")
# Populate the mesh function orientation

How is this information used in the assembler?

Harish