Hi
I've been working and studying deal.ii for 3 or 4 months. So far I been
able to set up a simple time dependent model of heat diffusion with free
and fixed boundary conditions. I also was able to establish material
properties based on material id's.
My question might be very simple. I want to set up a function to
calculate the heat flux in the surface based on a given 'external
temperature' (read from a external file) and the temperature over that
surface (i.e. newtons law of cooling). Based on step 7 I have this piece
of code:
typename DoFHandler<dim>::active_cell_iterator
cell = dof_handler.begin (),
endc = dof_handler.end ();
for (;cell != endc; ++cell)
{
cell_rhs = 0;
for (unsigned int face = 0;
face<GeometryInfo<dim>::faces_per_cell;
++face)
if (cell->face(face)->at_boundary()
&&
(cell->face(face)->boundary_indicator () == 2))
{
fe_face_values.reinit (cell,face);
for (unsigned int q_point = 0;
q_point < n_face_q_points;
++q_point)
{
const double neumann_value
= 'problematic-function';
for (unsigned int i = 0;
i < dofs_per_cell;
++i)
cell_rhs (i) += (neumann_value *
fe_face_values.shape_value(i,q_point)*
fe_face_values.JxW (q_point));
}
}
cell -> get_dof_indices (local_dof_indices);
for (unsigned int i = 0; i<dofs_per_cell; ++i)
{
system_rhs(local_dof_indices [i]) += cell_rhs (i);
}
}
Here I'm trying to establish the neumann boundary condition but in order
to determine the heat flux I need to know the value of temperature over
the face. Are these values the degrees of freedom over the surface? If
so, can I obtain them using get_dof_values (although I don't know
exactly how)?
I'll appreciate any clue you could give me.
Regards
Javier Muñoz
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