Hello Daniel,
Thanks for your reply and help. I am attaching a part of the code herewith.
Thanks and regards,
Anup.
On Tuesday, November 29, 2016 at 9:41:19 AM UTC-6, Daniel Arndt wrote:
>
> Anup,
>
> I am trying to implement the periodic boundary condition for a nonlinear
>> parabolic equation (scalar).
>> I have considered a *parallelepiped *as shown in the attached pdf. I
>> want to impose periodic
>> BC at x=0 and x=w surfaces. I have used an offset vector as appearing in
>> the piece of code
>> below, which I formed based on my understanding from the documentation
>> (it is tangential to the
>> surface x = w). Could you please tell
>> me if it is the correct expression. I think the problem is in this vector
>> only, because when I reduce the
>> angle theta to zero, it works. Boundary x =0 and x=w are numbered as 1
>> and 11, respectively.
>> I also tried with the offset vector : Tensor<1, dim>(0., 0., -
>> w*tan(theta))
>> Any suggestion and help would be appreciated.
>>
>> constraints_eta1.clear();
>> std::vector<GridTools::PeriodicFacePair<typename
>> DoFHandler<dim>::cell_iterator> > periodicity_vector1;
>> GridTools::collect_periodic_faces(dof_handler_eta, 1, 11, 0,
>> periodicity_vector1,
>> Tensor<1, dim>(0., 0.,
>> w*tan(theta)));
>>
>> DoFTools::make_periodicity_constraints<DoFHandler<dim>
>> >(periodicity_vector1, constraints_eta1);
>> constraints_eta1.close();
>>
> That looks and sounds correct if the vertices of the bounding
> parallelepiped have the coordinates
> (0|0|0), (w|0|tan(theta)*w), (0|h|0), (w|h|tan(theta)*w), (0|0|L),
> (w|0|L+tan(theta)*w), (0|h|L), (w|h|L+tan(theta)*w)
>
> Can you confirm that the coarse cells have the correct boundary
> indicators? Would you have a minimal code?
>
> Best,
> Daniel
>
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template <int dim>
void Solid<dim>::run()
{
make_grid();
system_setup();
}
////////////////////////////////////////////
template <int dim>
Point<dim> grid_y_transform (const Point<dim> &pt_in)
{
const double &x = pt_in[0];
const double &z = pt_in[2];
const double z_upper = 45.0 + 0.5413861341550015*x;
const double z_lower = 0.0 + 0.5413861341550015*x;
const double theta = z/45.0;
const double y_transform = (1-theta)*z_lower + theta*z_upper;
Point<dim> pt_out = pt_in;
pt_out[2] = y_transform;
return pt_out;
}
///////////////////////////////////////////////////////////////
template <int dim>
void Solid<dim>::make_grid()
{
std::vector< unsigned int > repetitions(dim, parameters.elements_per_edge);
repetitions[dim-3] = parameters.elements_per_width;
if (dim == 3)
repetitions[dim-2] = 1;
const Point<dim> bottom_left = (dim == 3 ? Point<dim>(0.0, -parameters.thickness, 0.0) : Point<dim>(0.0, 0.0));
const Point<dim> top_right = (dim == 3 ? Point<dim>(parameters.width, parameters.thickness,
parameters.length) :
Point<dim>(parameters.width, parameters.length));
GridGenerator::subdivided_hyper_rectangle(triangulation,
repetitions,
bottom_left,
top_right);
const double tol_boundary = 1e-6;
typename Triangulation<dim>::active_cell_iterator cell =
triangulation.begin_active(), endc = triangulation.end();
for (; cell != endc; ++cell)
for (unsigned int face = 0;
face < GeometryInfo<dim>::faces_per_cell; ++face)
if (cell->face(face)->at_boundary() == true)
{
if (std::abs(cell->face(face)->center()[0] - 0.0) < tol_boundary)
cell->face(face)->set_boundary_id(1);
else if (std::abs(cell->face(face)->center()[0] - parameters.width) < tol_boundary)
cell->face(face)->set_boundary_id(11);
}
GridTools::transform(&grid_y_transform<dim>, triangulation);
GridTools::scale(parameters.scale, triangulation);
}
/////////////////////////////////////////////////////////////////////
template <int dim>
void Solid<dim>::system_setup()
{
dof_handler_eta.distribute_dofs (fe_eta);
const unsigned int n_dofs_eta = dof_handler_eta.n_dofs();
constraints_eta1.clear();
std::vector<GridTools::PeriodicFacePair<typename DoFHandler<dim>::cell_iterator> > periodicity_vector1;
GridTools::collect_periodic_faces(dof_handler_eta, 1, 11, 0, periodicity_vector1,
Tensor<1, dim>(0., 0., 0.5413861341550015*parameters.width*1e-9));
DoFTools::make_periodicity_constraints<DoFHandler<dim> >(periodicity_vector1, constraints_eta1);
constraints_eta1.close();
}
