Hello Deal.ii Friends,
I want to set 2 constraints (P = 0 and \delta P = 0) on the scalar pressure
variable on a single point (4, 0.1) at the outlet. Here, \delta P is the
Newton's iteration update value for P.
I used "constraints_hp_nonzero" to interpolate the real boundary values for
my physical problem and "constraints_newton_boundary" to interpolate the
Newton updates values on the boundaries.
I found that one can only set one type of constraint on a singel index.
Therefore, the following snippet code would generate errors, since I was
trying to set 2 different constraints simultaneously on the same dof index.
Point<dim> point(4.0, 0.1);
std::set<unsigned int> constrained_dofs;
const unsigned int pressure_component = extractor_stokes_pressure.component;
for (const auto &cell :
dof_handler.active_cell_iterators())
{
if (cell->is_locally_owned() )
{
for (unsigned int v=0;
v<GeometryInfo<dim>::vertices_per_cell; ++v)
{
if (cell->vertex(v).distance(point) < 1e-8)
{
// get the index
unsigned int dof_index =
cell->vertex_dof_index(v,
pressure_component);
if (constrained_dofs.find(dof_index) ==
constrained_dofs.end())
{
pcout << "index" << dof_index <<
std::endl;
//constraints_newton_boundary.add_line(dof_index);
constraints_hp_nonzero.add_line(dof_index);
constrained_dofs.insert(dof_index);
}
}
}
}
}
Back to my problem.
If I want to successfully impose the 2 constraints: P=0 and delta P=0 on
point (4,0.1), does it exist a better way? Could you kindly give me some
hints?
I appreciate any reply to my question here.
Regards,
Lee
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