Thanks Martin for all the help! If I understand correctly, the first approach would assume that both the problems are solved in a fully coupled manner, with all fields updated simultaneously at each solve. For a staggered solution , where I solve the temperature first, and then the stress - I'd either have to manually compute the cell matching between the two objects, before assembling the vector, or abandon the SIMD vectorization, and compute the vector the "old-fashioned" way just for the coupling where information from the two vectors needs to be accessed simultaneously.
Subramanya. सुब्रह्मण्य . On Sun, Jan 5, 2025 at 1:51 AM 'Martin Kronbichler' via deal.II User Group < dealii@googlegroups.com> wrote: > Dear Subramanya, > > The actual cells associated with the integer indices 'cell' (that are > batches in case of SIMD vectorization) are not necessarily the same if you > create two separate MatrixFree objects and initialize each with the > respective DoFHandler for the two fields. If you intend to use coupled > problems like the thermal-stress problem you describe, you should use the > MatrixFree::reinit function that takes both DoFHandler objects as the > arguments to an std::vector<DoFHandler*> and respectively for the affine > constraints. Then, you can initialize FEEvaluation objects using the > 'dof_no' argument in the constructor: > https://www.dealii.org/developer/doxygen/deal.II/classFEEvaluation.html#ade40e452949cbefd4f7e6d5580af81c8 > - it is the second argument next to MatrixFree. > > You can also try to run with separate MatrixFree objects, but then you > need to manually link the two objects and one FEEvaluation needs to be > initialized with an array of cells (that you constructed manually). I have > done that in some applications, and there is at least one code inside > deal.II that does this: > https://github.com/dealii/dealii/blob/8f97fd0dca1eb878bc7ae9922ac89430cab800db/include/deal.II/multigrid/mg_transfer_global_coarsening.templates.h#L4041-L4068 > - but it is much less obvious, so I really recommend the first variant. > > I hope this helps! > > Best regards, > Martin > > Am 03.01.25 um 17:14 schrieb subramanya gautam: > > I am trying to implement a staggered thermal-elastic solver using the > matrix-free multigrid solver approach from step-37. I got an elasticity > solver and a thermal solver working and now I am trying to associate the > two. I have a shared triangulation, with two separate dof_handlers for the > thermal and stress problems. The question I have is when I do the assembly > loop, does the cell refer to the same cell for both the thermal and > elastic problems? > So from step-37, can I just call phi_temp.reinit(cell), and > phi_stress.reinit(cell), and have cell refer to the same physical cell in > the triangulation? > > > for (unsigned int cell = 0; > cell < system_matrix.get_matrix_free()->n_cell_batches(); > ++cell) > { > phi.reinit(cell); > for (const unsigned int q : phi.quadrature_point_indices()) > phi.submit_value(make_vectorized_array > <https://www.dealii.org/current/doxygen/deal.II/vectorization_8h.html#ad7d7e08942faeecf438c75a254e06cbe><double>(1.0), > q); > phi.integrate(EvaluationFlags::values > <https://www.dealii.org/current/doxygen/deal.II/namespaceEvaluationFlags.html#a9b7c6d689cb76386839d0d13640f59aeaf9825c682f693a6a200094641a0d6a58> > ); > phi.distribute_local_to_global(system_rhs); > } > Thanks! > Subramanya. > -- > 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. > To view this discussion visit > https://groups.google.com/d/msgid/dealii/d8f59b24-2a30-4ade-83e4-75bc72112afen%40googlegroups.com > <https://groups.google.com/d/msgid/dealii/d8f59b24-2a30-4ade-83e4-75bc72112afen%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > -- > 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. > To view this discussion visit > https://groups.google.com/d/msgid/dealii/71ea7f4c-19c8-43f6-9037-775aa504b470%40rub.de > <https://groups.google.com/d/msgid/dealii/71ea7f4c-19c8-43f6-9037-775aa504b470%40rub.de?utm_medium=email&utm_source=footer> > . > -- 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. To view this discussion visit https://groups.google.com/d/msgid/dealii/CAHCJNxN82c0u_L8VU31gBS0tK8WxpxkJXmjwB%2Bav5P2jx%2B4-qw%40mail.gmail.com.
