Hi Bastien,
Which version of deal.II are you using? There is the recently added
add_periodicity()
<https://www.dealii.org/8.4.0/doxygen/deal.II/classparallel_1_1distributed_1_1Triangulation.html#a9539cda687eeb08c602bceac11807987>
function
that helps join otherwise unrelated faces for distributed triangulations.
See also step-45 <https://www.dealii.org/8.4.0/doxygen/deal.II/step_45.html>
for
an example as to how it is used.
On a tangential but related note, this type of "periodic" boundary
condition is in all likelihood not appropriate for elasticity. See, for
example,
@Article{Miehe2003a,
Title = {Computational micro-to-macro transitions for
discretized micro-structures of heterogeneous materials at finite strains
based on the minimization of averaged incremental energy},
Author = {Miehe, Christian},
Journal = {Computer Methods in Applied Mechanics and
Engineering},
Year = {2003},
Number = {5},
Pages = {559--591},
Volume = {192}
}
for the correct definition of the periodicity constraint (namely a periodic
displacement jump based on the volume averaged deformation gradient) for
elasticity.
I hope that this helps,
J-P
On Wednesday, June 1, 2016 at 2:10:36 AM UTC+2, Bastien Lauras wrote:
>
> Hi,
>
> I am working on a 2D square, a incompressible neo-hookean material. I've
> used step 44 and modified it to work on a two field formulation (*u* and
> p).
> I am trying to implement periodic boundary conditions for the vertical
> displacement on lateral faces (right and left).
> My left face has boundary indicator 1, and my right face has boundary
> indicator 3.
>
> In the make_constraints function, I've added, after constraints.clear() :
>
> DoFTools::make_hanging_node_constraints (dof_handler_ref, constraints);
> // I have local refinement in my code
>
> std::vector<GridTools::PeriodicFacePair<typename
> DoFHandler<dim>::cell_iterator> >
> periodicity_vector;
>
> const unsigned int direction = 0; // I've tried 0 and 1, I didn't
> understan what it really was
>
> GridTools::collect_periodic_faces(dof_handler_ref, 1, 3, direction,
> periodicity_vector);
>
> const FEValuesExtractors::Scalar x_displacement(0);
> const FEValuesExtractors::Scalar y_displacement(1);
>
> DoFTools::make_periodicity_constraints<DoFHandler<dim> >
> (periodicity_vector, constraints, fe.component_mask(y_displacement));
>
>
> And then I apply Dirichlet boundary conditions on face 1 and 3 on the
> horizontal displacement (x_displacement).
> I've also added the command :
>
> DoFTools::make_hanging_node_constraints (dof_handler_ref, constraints);
>
> before making my sparsity pattern.
> My triangulation is not a parallel::distributed one. I'm working on
> multithreads with the workstream::run of step 44.
>
>
> The problem is that my periodic boundary conditions are not enforced. The
> make_periodicity_constraints command does not change the number of
> constrained degrees of freedom (that I compute using a loop over the DOFs
> and calling constraints.is_constrained(i)).
> And moreover, I can see on my outputs that there is definitely no
> periodicity on my vertical displacement.
>
> Where can the problem come from?
>
> Thanks a lot for your help beforehand!
>
> Bastien Lauras
>
>
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