periodic_box.h

/*  ______________________________________________________________________
 *
 *  ExaDG - High-Order Discontinuous Galerkin for the Exa-Scale
 *
 *  Copyright (C) 2021 by the ExaDG authors
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *  ______________________________________________________________________
 */
 
#ifndef APPLICATIONS_GRID_TOOLS_PERIODIC_BOX_H_
#define APPLICATIONS_GRID_TOOLS_PERIODIC_BOX_H_
 
// deal.II
#include <deal.II/distributed/tria.h>
#include <deal.II/grid/grid_generator.h>
#include <deal.II/grid/grid_tools.h>
 
// ExaDG
#include <exadg/grid/deformed_cube_manifold.h>
 
namespace ExaDG
{
template<int dim>
void
create_periodic_box(dealii::Triangulation<dim> &                             triangulation,
                    unsigned int const                                       n_refine_space,
                    std::vector<dealii::GridTools::PeriodicFacePair<
                      typename dealii::Triangulation<dim>::cell_iterator>> & periodic_faces,
                    unsigned int const                                       n_subdivisions,
                    double const                                             left,
                    double const                                             right,
                    bool const   curvilinear_mesh = false,
                    double const deformation      = 0.1)
{
  dealii::GridGenerator::subdivided_hyper_cube(triangulation, n_subdivisions, left, right);
 
  if(curvilinear_mesh)
  {
    unsigned int const frequency = 2;
    apply_deformed_cube_manifold(triangulation, left, right, deformation, frequency);
  }
 
  for(auto const & cell : triangulation.cell_iterators())
  {
    for(unsigned int const face_number : cell->face_indices())
    {
      // x-direction
      if((std::fabs(cell->face(face_number)->center()(0) - left) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(0);
      else if((std::fabs(cell->face(face_number)->center()(0) - right) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(1);
      // y-direction
      else if((std::fabs(cell->face(face_number)->center()(1) - left) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(2);
      else if((std::fabs(cell->face(face_number)->center()(1) - right) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(3);
      // z-direction
      else if(dim == 3 and (std::fabs(cell->face(face_number)->center()(2) - left) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(4);
      else if(dim == 3 and (std::fabs(cell->face(face_number)->center()(2) - right) < 1e-12))
        cell->face(face_number)->set_all_boundary_ids(5);
    }
  }
 
  dealii::GridTools::collect_periodic_faces(triangulation, 0, 1, 0 /*x-direction*/, periodic_faces);
  dealii::GridTools::collect_periodic_faces(triangulation, 2, 3, 1 /*y-direction*/, periodic_faces);
  if(dim == 3)
    dealii::GridTools::collect_periodic_faces(
      triangulation, 4, 5, 2 /*z-direction*/, periodic_faces);
 
  triangulation.add_periodicity(periodic_faces);
 
  // perform global refinements
  triangulation.refine_global(n_refine_space);
}
 
} // namespace ExaDG
 
#endif /* APPLICATIONS_GRID_TOOLS_PERIODIC_BOX_H_ */