Hi,
any chance I could get your help with that? I'm trying to use the code of @Jie-Cheng <https://github.com/Jie-Cheng> for Block Preconditioner (https://github.com/dealii/code-gallery/tree/893bdb5b0a770758fce98859ab4d137f95e62a50/time_dependent_navier_stokes) for a case of fully periodic boundary conditions, but then it gives me the error that [B^T (diag M)^{-1} B]^{-1} not invertible. Any ideas why this could happen or how could I fix it? I have increased the number of iterations for the CG solver and I also tried to use gmres, but none of them ways worked. The way I impose the Periodic Boundary conditions is the following. I have a unit square domain with boundary ids 1,2,3 and 4 for the four sides. std::vector<GridTools::PeriodicFacePair<typename Triangulation::cell_iterator> > periodicity_vector; std::vector<GridTools::PeriodicFacePair<typename Triangulation::cell_iterator> > periodicity_vector1; FullMatrix<double> rotation_matrix(dim); rotation_matrix[0][0]=1.; rotation_matrix[1][1]=1.; GridTools::collect_periodic_faces(triangulation, 2, 3, 1, periodicity_vector, Tensor<1, dim>(), rotation_matrix); GridTools::collect_periodic_faces(triangulation, 4, 1, 0, periodicity_vector1, Tensor<1, dim>(), rotation_matrix); triangulation.add_periodicity(periodicity_vector); triangulation.add_periodicity(periodicity_vector1); DoFTools::make_periodicity_constraints(dof_handler, 2, 3, 1, constraints); DoFTools::make_periodicity_constraints(dof_handler, 4, 1, 0, constraints); Thank you for your help in advance, I've been stuck with that a long time now and I really don't understand what's the problem. Best, Magda -- 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.
