Bernhard,
> I' am trying to solve the stationary Navier-Stokes benchmark Problem with
> configuration 2 given in
>
> https://ganymed.math.uni-heidelberg.de/Paper/braackrichter-200410.pdf
>
> The initial mesh is attached.
>
> Here i used to following code fragment to set the boundary conditions for the
> newton update:
>
>
> template
> void set_newton_bc(DoFHandler& dof_handler, ConstraintMatrix &
> constraints, Dirichlet_Boundary dirichlet_doundary_enforcement =
> Dirichlet_Boundary::strong)
> {
>
> std::vector component_mask(dof_handler.get_fe(0).n_components(),
> true);
> component_mask[dim] = false;
>
> VectorTools::interpolate_boundary_values(dof_handler, 0,
> ZeroFunction(dof_handler.get_fe(0).n_components()), constraints,
> component_mask);
> VectorTools::interpolate_boundary_values(dof_handler, 2,
> ZeroFunction(dof_handler.get_fe(0).n_components()), constraints,
> component_mask);
>
>
>
> VectorTools::interpolate_boundary_values(dof_handler, 80,
> ZeroFunction(dof_handler.get_fe(0).n_components()), constraints,
> component_mask);
> IndexSet indexset;
> std::set boundaryids;
> boundaryids.clear();
> boundaryids.insert(80);
>
> DoFTools::extract_boundary_dofs(dof_handler,ComponentMask(component_mask),indexset,boundaryids);
> indexset.print(std::cout);
> }
>
>
> The last part of the code fragment is just to get an output of the index set
> of the DoF which belong to boundary 80.
So to summarize, you are interpolating boundary conditions on boundaries with
boundary_id 0, 2, 80, and then you are outputting all DoFs on boundary 80.
> The set is given by
> [...]
>
> If manually look in the set of active cells for the DoFs which belong to
> one
> of the "problematic" points i find
>
>
> *231* : comp =0 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 0
> 636 : comp =0 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 1
> *2048* : comp =1 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 0
> 2453 : comp =1 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 1
> *3865* : comp =2 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 0
> 4270 : comp =2 at the node located in 4.50e-01 2.50e-01
> 2.05e-01 on level 1
>
> However the bold ones are not contained in the indexset, an do have troubles
> at this points, when i would like to apply
> constraintmatrix.distribute(newton_update);
Even though I might have an idea where you are going, your message does not
actually contain a *question* :-) Can you describe what you expect, what you
see, and how the two differ? In other words, what the actual *problem* is?
Best
W.
--
Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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