Hi everyone,
Instead of prescribing classical Dirichlet boundary conditions (i.e. the
values for the solution field on the boundary) I am trying to impose the
values for a specific degree of freedom inside my material. My idea was to
iterate over all cells and their faces. Then I use the location of the
center of the face to identify the faces, that have the right position.
When I loop over all degrees of freedom of the face, I can find the DOFs
that correspond to the correct base element, put these into a
"boundary_values" vector and then use MatrixTools::apply_boundary_values to
apply these values (see the following code snippet).
* typename hp::DoFHandler<dim>::active_cell_iteratorcell =
dof_handler.begin_active();for (; cell!=dof_handler.end(); ++cell){
for (unsigned int f = 0; f < GeometryInfo<dim>::faces_per_cell; ++f)
const Point<dim> face_center = cell->face(f)->center(); if
(face_center[2] == 5.0) {
cell->face(f)->get_dof_indices(local_dof_indices_face,0);
for(unsigned int i = 0; i < dofs_per_face; ++i) {
const unsigned int i_group =
fe_face.system_to_base_index(i).first.first; if
(i_group == V_dof) {
boundary_values[local_dof_indices_face[i]]=0; }
} }}MatrixTools::apply_boundary_values (boundary_values,
system_matrix,
locally_relevant_solution_update, system_rhs,false);*
Here I try to apply the value for the electric potential (a scalar value,
associated with the V_dof) on the middle plane of a cube with the
sidelength 10 (i.e. *face_center[2] == 5.0*)
This works fine, if the polynomial order of the FE_Q element is 1, however,
if I increase the order it seems like the value is not applied to the DOFs
between the vertices of the cell (see attached picture). When I apply the
boundary conditions on the surfaces using
*VectorTools::interpolate_boundary_values
*I do not have this issue.
Can anyone give me a tip, what might be the problem?
Thank you,
Markus
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