Hello all, I am writing an MPI parallel DG code for linear advection equation, just for understanding the parallel programming paradigm of deal.II.
To evaluate numerical flux at a face connecting two subdomains, I only require the solution (from a different mpi process) at dofs which lie on the face; the dofs which lie inside the neighboring cell (of the neighbor subdomain) are not required. Consequently, I think the ghost indices for my solution vector would be those provided by the function DoFTools::dof_indices_with_subdomain_association() <https://www.dealii.org/current/doxygen/deal.II/namespaceDoFTools.html#ab90e386944d5b107b6694f742d57d960>, rather than DoFTools::extract_locally_relevant_dofs() <https://www.dealii.org/current/doxygen/deal.II/namespaceDoFTools.html#af0eef74bf66f0bfa8847f66fe6c8908d>. However, the documentation of the former function states Note that this function is of questionable use for DoFHandler objects built > on parallel::distributed::Triangulation since in that case ownership of > individual degrees of freedom by MPI processes is controlled by the DoF > handler object, not based on some geometric algorithm in conjunction with > subdomain id. In particular, the degrees of freedom identified by the > functions in this namespace as associated with a subdomain are not the same > the DoFHandler class identifies as those it owns. What is the meaning of the second line? I suppose this has something to do with the FiniteElement type of the dof handler. Does this mean to say that irrespective of whether the FiniteElement has dofs on cell faces or not, this function approves a dof if it is geometrically residing on a face? This behaviour is actually what I want because although FE_DGQ element doesn't attach any dofs to cell faces, I want to get dof indices of the dofs (geometrically) lying on the face. Thanks! Vachan -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/f1a506a4-f652-43fd-9b02-c948f1eca49d%40googlegroups.com.
