Dear All,
I still have problem with implying boundary condition on the curved domain.
consider we produce quarter of a ring in 2D with the function
"quarter_hyper_shell" and want to impose Neumann boundary condition on the
outer surface. In fact we have a force normal to this surface. The other
boundary conditions for straight lines are axisymmetry boundary condition.
What I did is given as follow:
for (unsigned int face=0; face<GeometryInfo<dim>::faces_per_cell; ++face)
if (cell->face(face)->at_boundary() == true
&& cell->face(face)->boundary_id() == 11)
{
scratch.fe_face_values_ref.reinit(cell, face);
for (unsigned int f_q_point=0; f_q_point<n_q_points_f; ++f_q_point)
{
const double time_ramp = (time.current() / time.end());
const double eta_orderM =
(local_quadrature_point_history[f_q_point].get_eta_boundary_value_mechanic())
* time_ramp; *// The multiplication of Neumann value (for example heat
flux in heat equation or traction force normal to the surface in mechanic)
and time_ramp*.
static const Tensor<1, dim> normals =
scratch.fe_face_values_ref.normal_vector(f_q_point); * // Extracting the
normal vectors of the selected face*
const Tensor<1, dim> neumann_value = eta_orderM * normals;
for (unsigned int i=0; i<dofs_per_cell; ++i)
{
const unsigned int i_group =fe.system_to_base_index(i).first.first;
if (i_group == u_dof)
{
const unsigned int component_i =
fe.system_to_component_index(i).first;
const double JxW = scratch.fe_face_values_ref.JxW(f_q_point);
data.cell_rhs(i) -= neumann_value[component_i] *
scratch.fe_face_values_ref.shape_value(i, f_q_point) * JxW;
}
}
}
}
The problem is that with changing the sign of the data.cell_rhs(i), the
direction of the force did not change. In fact, The ring is under
compression, however, in the result, it seems that it is under tension. It
would be very kind of you if you tell me which part I am making mistake. I
know this website is not for code reviewing, but I really appreciate your
time and help.
Bests,
Benhour
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