solver.hpp

/******************************************************************************
 * Copyright (C) Siarhei Uzunbajakau, 2023.
 *
 * This program is free software. You can use, modify, and redistribute it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 3 or (at your option) any later version.
 * This program is distributed without any warranty.
 *
 * Refer to COPYING.LESSER for more details.
 ******************************************************************************/
 
#ifndef SolverMMS_H__
#define SolverMMS_H__
 
#include <deal.II/grid/grid_in.h>
#include <deal.II/grid/grid_out.h>
#include <deal.II/grid/grid_tools.h>
 
#include "exact_solution.hpp"
#include "settings.hpp"
#include "static_scalar_solver.hpp"
 
using namespace StaticScalarSolver;
 
template<int dim>
class SolverMMS
  : public SettingsMMS
  , public Solver<dim>
{
public:
  SolverMMS() = delete;
 
  SolverMMS(unsigned int p,
            unsigned int mapping_degree,
            unsigned int r,
            std::string fname)
    : Solver<dim>(p,
                  mapping_degree,
                  1, // The PDE right-hand side is free-current density.
                  fname,
                  &exact_solution,
                  false, // Is axisymmetric.
                  false, // Is vector potential.
                  print_time_tables,
                  project_exact_solution)
    , fname(fname)
  {
    if (DIMENSION__ == 2) {
      if (HYPERCUBE__ == 1) {
        fname_mesh = "../../gmsh/data/square_r" + std::to_string(r) + ".msh";
      } else {
        fname_mesh = "../../gmsh/data/circle_r" + std::to_string(r) + ".msh";
      }
    } else {
      if (HYPERCUBE__ == 1) {
        fname_mesh = "../../gmsh/data/cube_r" + std::to_string(r) + ".msh";
      } else {
        fname_mesh = "../../gmsh/data/sphere_r" + std::to_string(r) + ".msh";
      }
    }
 
    Solver<dim>::run();
  }
 
  ~SolverMMS() = default;
 
private:
  const std::string fname;
 
  std::string fname_mesh;
 
  const ExactSolutionMMS_PHI<dim> exact_solution;
 
  virtual void make_mesh() override final;
  virtual void fill_dirichlet_stack() override final;
  virtual void solve() override final;
};
 
template<int dim>
void
SolverMMS<dim>::fill_dirichlet_stack()
{
  Solver<dim>::dirichlet_stack = { { bid_dirichlet, &exact_solution } };
}
 
template<int dim>
void
SolverMMS<dim>::solve()
{
  SolverControl control(Solver<dim>::system_rhs.size(),
                        1e-8 * Solver<dim>::system_rhs.l2_norm(),
                        false,
                        false);
 
  if (log_cg_convergence)
    control.enable_history_data();
 
  GrowingVectorMemory<Vector<double>> memory;
  SolverCG<Vector<double>> cg(control, memory);
 
  PreconditionJacobi<SparseMatrix<double>> preconditioner;
  preconditioner.initialize(Solver<dim>::system_matrix, 1.0);
 
  cg.solve(Solver<dim>::system_matrix,
           Solver<dim>::solution,
           Solver<dim>::system_rhs,
           preconditioner);
 
  Solver<dim>::constraints.distribute(Solver<dim>::solution);
 
  if (log_cg_convergence) {
    const std::vector<double> history_data = control.get_history_data();
 
    std::ofstream ofs(fname + "_cg_convergence.csv");
 
    unsigned int i = 1;
    for (auto item : history_data) {
      ofs << i << ", " << item << "\n";
      i++;
    }
    ofs.close();
  }
}
 
template<int dim>
void
SolverMMS<dim>::make_mesh()
{
  GridIn<dim> gridin;
  gridin.attach_triangulation(Solver<dim>::triangulation);
 
  std::ifstream ifs(fname_mesh);
  gridin.read_msh(ifs);
}
#endif