some question about the move mesh function

[huyanzhuo]

Dear All:

i use the move_mesh function just like step-42

template < int dim >

    void step<dim>::move_mesh(const TrilinosWrappers::MPI::Vector &state_change) const

    {

      pcout<<"moving the mesh ..." <<std::endl;

      std::vector<bool> vertex_touched(triangulation.n_vertices(), false);

      for (typename DoFHandler<dim>::active_cell_iterator cell =dof_handler.begin_active();cell != dof_handler.end(); ++cell)

        if (cell->is_locally_owned())                                                       

          for (unsigned int v = 0; v < GeometryInfo<dim>::vertices_per_cell; ++v)         

            {

              if(vertex_touched[cell->vertex_index(v)] == false)

              {

                vertex_touched[cell->vertex_index(v)] = true;

                Point<dim> vertex_displacement;

                for (unsigned int d = 0; d < dim; ++d)                                 

                  vertex_displacement[d] = state_change(cell->vertex_dof_index(v, d));

                cell->vertex(v) += vertex_displacement;

              }

            }

    }

it works well on my own computer. but when use the mpirun in a server, the result shows a departure on the boundry of mesh belongs to  different process

does anyone has the same problem?

[Daniel Arndt]

huyanzhou,

you might want to have a look at parallel::distributed::Triangulation::communicate_locally_moved_vertices (https://www.dealii.org/current/doxygen/deal.II/classparallel_1_1distributed_1_1Triangulation.html#a247598f1323a9f847832e60d6c840469).

Best,

Daniel

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[huyanzhuo]

thanks very much for your reply!

I try to use the communicate_locally_moved_vertices, it fixes the departure of mesh belongs to different mesh . but there still remains some problem 

you can see that the mesh is consistent on the boundry, but not smooth in the inner mesh ,there are some shallow hole  on the surface

my code is as follows

    template < int dim >

    void step<dim>::move_mesh(const TrilinosWrappers::MPI::Vector &state_change) 

    {

      pcout<<"moving the mesh ..." <<std::endl;

      std::vector<bool> vertex_touched(triangulation.n_vertices(), false);

      parallel::distributed::Triangulation< dim > *distributed_triangulation = &triangulation;

      const std::vector<bool> locally_owned_vertices = GridTools::get_locally_owned_vertices(triangulation);

      for (typename DoFHandler<dim>::active_cell_iterator cell =dof_handler.begin_active();cell != dof_handler.end(); ++cell)

        if (cell->is_locally_owned())                                                       

          for (unsigned int v = 0; v < GeometryInfo<dim>::vertices_per_cell; ++v)         

            {

              if(vertex_touched[cell->vertex_index(v)] == false)

              {

                vertex_touched[cell->vertex_index(v)] = true;

                Point<dim> vertex_displacement;

                for (unsigned int d = 0; d < dim; ++d)                                 

                  vertex_displacement[d] = state_change(cell->vertex_dof_index(v, d));

                cell->vertex(v) += vertex_displacement;

              }

            }

      distributed_triangulation->communicate_locally_moved_vertices(locally_owned_vertices);

      typename Triangulation<dim>::active_cell_iterator

      cell = triangulation.begin_active(),

      endc = triangulation.end();

      for (; cell!=endc; ++cell)

        if (!cell->is_artificial())

          for (unsigned int face=0; face<GeometryInfo<dim>::faces_per_cell; ++face)

            if (cell->face(face)->has_children() && !cell->face(face)->at_boundary())

            {

              // this face has hanging nodes

              if (dim==2)

                cell->face(face)->child(0)->vertex(1) = (cell->face(face)->vertex(0) + cell->face(face)->vertex(1)) / 2;

              else if (dim==3)

              {

                cell->face(face)->child(0)->vertex(1) = .5*(cell->face(face)->vertex(0) +cell->face(face)->vertex(1));

                cell->face(face)->child(0)->vertex(2) = .5*(cell->face(face)->vertex(0) +cell->face(face)->vertex(2));

                cell->face(face)->child(1)->vertex(3) = .5*(cell->face(face)->vertex(1) +cell->face(face)->vertex(3));

                cell->face(face)->child(2)->vertex(3) = .5*(cell->face(face)->vertex(2) +cell->face(face)->vertex(3));

                // center of the face

                cell->face(face)->child(0)->vertex(3) = .25*(cell->face(face)->vertex(0)

                                                             +cell->face(face)->vertex(1)

                                                             +cell->face(face)->vertex(2)

                                                             +cell->face(face)->vertex(3));

              }

            }

    }

i follow the example in  GridTools::distort_random() 

在 2019年10月5日星期六 UTC+8上午1:07:13，Daniel Arndt写道：

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[Daniel Arndt]

huyanzhou,

I try to use the communicate_locally_moved_vertices, it fixes the departure of mesh belongs to different mesh . but there still remains some problem

[...]

you can see that the mesh is consistent on the boundry, but not smooth in the inner mesh ,there are some shallow hole  on the surface

Can you explain more precisely what doesn't work as expected? Is this a problem you only see when running with multiple MPI processes?

What is the "inner mesh" for you? Do you refer to faces with children? Can you point out which vertices you think are set wrongly?

 

my code is as follows

[...]

It seems that your idea is to first move vertices according to some displacement function and then to "correct" hanging vertices to be placed inside the neighboring face.

That looks OK for standard orientation but might be problematic otherwise. You should be able to achieve the same effect when you only apply hanging node constraints to your

displacement vector.

Best,

Daniel

[huyanzhuo]

thanks for your reply！

 i got the problem solved. my fault is the misuse of communicate_locally_moved_vertices function. 

i got the "shallow hole" because i move the mesh when the mesh is deformed , the mpi processor does't know the right place of ghost layer cell.

i solve the problem by correct the whole move vector and return to the original mesh , which i refine and coarsen in the later step. after i finished the refinement , just add the whole move vector again the there is no "shallow hole" any more.

在 2019年10月5日星期六 UTC+8下午11:34:18，Daniel Arndt写道：