stokes_matrix_free_global_coarsening.h

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/*
  Copyright (C) 2011 - 2025 by the authors of the ASPECT code.

  This file is part of ASPECT.

  ASPECT 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 2, or (at your option)
  any later version.

  ASPECT 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 ASPECT; see the file LICENSE.  If not see
  <http://www.gnu.org/licenses/>.
*/

#ifndef _aspect_simulator_solver_stokes_matrix_free_global_coarsening_h
#define _aspect_simulator_solver_stokes_matrix_free_global_coarsening_h

#include <aspect/global.h>
#include <aspect/simulator/solver/stokes_matrix_free.h>
#include <aspect/simulator/solver/matrix_free_operators.h>

#include <deal.II/matrix_free/matrix_free.h>
#include <deal.II/matrix_free/operators.h>
#include <deal.II/matrix_free/fe_evaluation.h>

#include <deal.II/multigrid/mg_constrained_dofs.h>
#include <deal.II/multigrid/multigrid.h>
#include <deal.II/multigrid/mg_transfer_matrix_free.h>
#include <deal.II/multigrid/mg_transfer_global_coarsening.templates.h>
#include <deal.II/multigrid/mg_tools.h>
#include <deal.II/multigrid/mg_coarse.h>
#include <deal.II/multigrid/mg_smoother.h>
#include <deal.II/multigrid/mg_matrix.h>

namespace aspect
{
  template <int dim, int velocity_degree>
  class StokesMatrixFreeHandlerGlobalCoarseningImplementation: public StokesMatrixFreeHandler<dim>
  {
    public:
      StokesMatrixFreeHandlerGlobalCoarseningImplementation(Simulator<dim> &simulator,
                                                            const Parameters<dim> &parameters);

      ~StokesMatrixFreeHandlerGlobalCoarseningImplementation() override = default;

      void initialize() override;

      std::string name() const override;

      StokesSolver::SolverOutputs
      solve(const LinearAlgebra::BlockSparseMatrix &system_matrix,
            const LinearAlgebra::BlockVector &system_rhs,
            const bool solve_newton_system,
            const double last_pressure_normalization_adjustment,
            LinearAlgebra::BlockVector &solution_vector) override;

      void setup_dofs() override;

      void assemble() override;

      void build_preconditioner() override;

      static
      void declare_parameters (ParameterHandler &prm);

      void parse_parameters (ParameterHandler &prm) override;

      std::size_t get_dof_handler_memory_consumption() const override;

      std::size_t get_mg_transfer_memory_consumption() const override;

      std::size_t get_constraint_memory_consumption() const override;

      std::size_t get_cell_data_memory_consumption() const override;

    private:
      void evaluate_material_model();

      void correct_stokes_rhs();


      Simulator<dim> &sim;

      bool print_details;

      bool do_timings;

      double minimum_viscosity;
      double maximum_viscosity;

      FESystem<dim> fe_v;
      FESystem<dim> fe_p;
      FESystem<dim> fe_projection;

      MatrixFreeStokesOperators::OperatorCellData<dim, GMGNumberType> active_cell_data;

      MGLevelObject<MatrixFreeStokesOperators::OperatorCellData<dim, GMGNumberType>> level_cell_data;

      using StokesMatrixType = MatrixFreeStokesOperators::StokesOperator<dim,velocity_degree,double>;
      using SchurComplementMatrixType = MatrixFreeStokesOperators::MassMatrixOperator<dim,velocity_degree-1,double>;
      using ABlockMatrixType = MatrixFreeStokesOperators::ABlockOperator<dim,velocity_degree,double>;
      using BTBlockOperatorType = MatrixFreeStokesOperators::BTBlockOperator<dim,velocity_degree,double>;
      using GMGSchurComplementMatrixType = MatrixFreeStokesOperators::MassMatrixOperator<dim,velocity_degree-1,GMGNumberType>;
      using GMGABlockMatrixType = MatrixFreeStokesOperators::ABlockOperator<dim,velocity_degree,GMGNumberType>;

      StokesMatrixType stokes_matrix;
      ABlockMatrixType A_block_matrix;
      BTBlockOperatorType BT_block;
      SchurComplementMatrixType Schur_complement_block_matrix;

      MGLevelObject<GMGABlockMatrixType> mg_matrices_A_block;
      MGLevelObject<GMGSchurComplementMatrixType> mg_matrices_Schur_complement;

      MGConstrainedDoFs mg_constrained_dofs_A_block;
      MGConstrainedDoFs mg_constrained_dofs_Schur_complement;
      MGConstrainedDoFs mg_constrained_dofs_projection;

      unsigned int min_level;
      unsigned int max_level;

      std::vector<std::shared_ptr<MatrixFree<dim,double>>> matrix_free_objects;

      std::vector<std::shared_ptr<const Triangulation<dim, dim>>> trias;

      MGLevelObject<DoFHandler<dim>> dofhandlers_v;
      MGLevelObject<DoFHandler<dim>> dofhandlers_p;
      MGLevelObject<DoFHandler<dim>> dofhandlers_projection;

      MGLevelObject<AffineConstraints<double>> constraints_v;
      MGLevelObject<AffineConstraints<double>> constraints_p;

#if DEAL_II_VERSION_GTE(9,6,0)
      using transfer_t = MGTransferMF<dim, GMGNumberType>;
#else
      using transfer_t = MGTransferGlobalCoarsening<dim, ::LinearAlgebra::distributed::Vector<GMGNumberType>>;
#endif
      MGLevelObject<MGTwoLevelTransfer<dim, ::LinearAlgebra::distributed::Vector<GMGNumberType>>> transfers_v;
      MGLevelObject<MGTwoLevelTransfer<dim, ::LinearAlgebra::distributed::Vector<GMGNumberType>>> transfers_p;
      std::unique_ptr<transfer_t> mg_transfer_A_block;
      std::unique_ptr<transfer_t> mg_transfer_Schur_complement;
  };
}

#endif