Dear all, I am now solving a problem using adaptive finite element method. The boundary condition is Dirichlet condition. When the cells on boundary are locally refined, the hanging node constraints are conflicting with inhomogeneous constraints.
In Constraints on degrees of freedom <https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html>, section Dealing with conflicting constraints, it says: If you want the hanging node constraints to win, then first build these through the DoFTools::make_hanging_node_constraints() <https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html#ga3eaa31a679484e80c193e74e8a967dc8> function. Then interpolate the boundary values using VectorTools::interpolate_boundary_values() <https://www.dealii.org/8.4.1/doxygen/deal.II/namespaceVectorTools.html#af6f700f193e9d5b52e9efe55e9b872d5> into the same ConstraintMatrix <https://www.dealii.org/8.4.1/doxygen/deal.II/classConstraintMatrix.html> object. If the latter function encounters a boundary node that already is constrained, it will simply ignore the boundary values at this node and leave the constraint untouched. But in documentation of VectorTools::project_boundary_values_curl_conforming <https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html#ga1c6685360c01c9c46eeb7575e8ef68ac>, it says: If the ConstraintMatrix <https://www.dealii.org/8.4.1/doxygen/deal.II/classConstraintMatrix.html> constraints contained values or other constraints before, the new ones are added or the old ones overwritten, if a node of the boundary part to be used was already in the list of constraints. This is handled by using inhomogeneous constraints. Please note that when combining adaptive meshes and this kind of constraints, the Dirichlet conditions should be set first, and then completed by hanging node constraints, in order to make sure that the discretization remains consistent. See the discussion on conflicting constraints in the module on Constraints on degrees of freedom <https://www.dealii.org/8.4.1/doxygen/deal.II/group__constraints.html>. I was totally confused. Which one is right? Best regards, Ce Qin -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
