The picture I mentioned can we viewed at this link. https://ibb.co/1nrRvfr
Reza On Wednesday, July 10, 2019 at 8:09:51 PM UTC-7, Reza Rastak wrote: > > Thank you Daniel, > > I think the way I described the question was a little vague, so I like to > clarify it. Consider the simplified mesh (shown below) with 30 cells, 42 > vertices, and 42 dofs. My desired constraint specifies that all the dofs > corresponding to the vertices on the right edge must have the same value. > So if I call the unknown field 'u', then I like to enforce u6 = u13 = u20 = > u27 = u34 = u41. In my current code, I do something similar to: > > constraint_matrix.reinit(locally_relevant_dofs); > constraint_matrix.add_entry(34, 41, 1.0); > constraint_matrix.add_entry(27, 41, 1.0); > constraint_matrix.add_entry(20, 41, 1.0); > constraint_matrix.add_entry(13, 41, 1.0); > constraint_matrix.add_entry(6, 41, 1.0); > > It works in the serial case. However, it doesn't work when I use multiple > MPI processes. For my actual mesh, it breaks when n_processes >= 5. > Basically I have to make sure that dof 41 is included in the relevant dofs > of all the processes. How to I do that? I think this type of constraint is > different than a periodic boundary condition and I could not find a > dedicated function that takes care of it. > > Thanks, > Reza > > > > > On Wednesday, July 10, 2019 at 7:24:47 PM UTC-7, Daniel Arndt wrote: >> >> Reza, >> >> What exactly do you mean by "link all the dofs of all the nodes along an >> edge of the body together"? >> From the error message above, I assume that you want to identify certain >> degrees of freedom via a ConstraintMatrix (or AffineConstraints) object. >> That is basically what DoFTools::make_periodicity_constraints is doing as >> well. Are you trying to do something similar? >> In any way, you need to make sure that the ConstraintMatrix (or >> AffineConstraints) object can store all the degrees of freedom you want to >> constrain. >> This is normally the set of locally relevant degrees and freedoms and the >> reason why you normally do >> >> constraints.reinit >> <https://www.dealii.org/9.0.0/doxygen/deal.II/classConstraintMatrix.html#ac2726821354883ac97fe7e6181de9792> >> >> (locally_relevant_dofs); >> >> In your case, you need to make sure that you extend this IndexSet by the >> degrees of freedom you want to constrain. Furthermore, all processes need >> to know about all >> the constraints related to these constraints. There is >> AffineConstraints::is_consistent_in_parallel ( >> https://www.dealii.org/current/doxygen/deal.II/classAffineConstraints.html#ad5fb8d3ca686a76ba33eb82d7f52b5fd >> ) >> that checks that this is the case. Of course, you need to pass the >> modified IndexSet there as well instead of just the locally relevant dofs. >> >> Best, >> Daniel >> >> >> Am Mi., 10. Juli 2019 um 20:48 Uhr schrieb Reza Rastak < >> reza....@gmail.com>: >> >>> Hi, >>> >>> >>> I like to link all the dofs of all the nodes along an edge of the body >>> together. So I find the first dof (dof i) located on the edge and then I >>> try to link all the dofs on that edge (except i) to dof i. It does not work >>> if I have sufficiently large number of processes where that edge is chopped >>> by different MPI processes. I know why it does not work, but I don't know >>> any methods that can provide my desired dof constraints. Anyone has >>> attempted to solve something similar? >>> >>> >>> This is the error that I get with 8 MPI processes. >>> >>> -------------------------------------------------------- >>> >>> An error occurred in line <1607> of file >>> </opt/local/dealii-9/deal.II-v9.0.1/include/deal.II/lac/constraint_matrix.h> >>> >>> in function >>> >>> void >>> dealii::ConstraintMatrix::add_entry(dealii::ConstraintMatrix::size_type, >>> dealii::ConstraintMatrix::size_type, double) >>> >>> The violated condition was: >>> >>> !local_lines.size() || local_lines.is_element(column) >>> >>> Additional information: >>> >>> The index set given to this constraint matrix indicates constraints >>> using degree of freedom 580 should not be stored by this object, but a >>> constraint for degree of freedom 736 uses it. >>> >>> -------------------------------------------------------- >>> >>> >>> Regards, >>> >>> >>> Reza >>> >>> >>> -- >>> 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 dea...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/dealii/31e7aedd-b087-41d4-a412-0e211bcb27bd%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/dealii/31e7aedd-b087-41d4-a412-0e211bcb27bd%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- 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. 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