time_int_gen_alpha_base.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 EXADG_TIME_INTEGRATION_TIME_INT_GEN_ALPHA_BASE_H_
#define EXADG_TIME_INTEGRATION_TIME_INT_GEN_ALPHA_BASE_H_
 
// deal.II
#include <deal.II/lac/la_parallel_vector.h>
 
// ExaDG
#include <exadg/time_integration/enum_types.h>
#include <exadg/time_integration/time_int_base.h>
 
namespace ExaDG
{
template<typename Number>
class TimeIntGenAlphaBase : public TimeIntBase
{
public:
  typedef dealii::LinearAlgebra::distributed::Vector<Number> VectorType;
 
  TimeIntGenAlphaBase(double const &       start_time_,
                      double const &       end_time_,
                      unsigned int const   max_number_of_time_steps_,
                      double const         spectral_radius_,
                      GenAlphaType const & gen_alpha_type_,
                      RestartData const &  restart_data_,
                      MPI_Comm const &     mpi_comm_,
                      bool const           is_test_);
 
  double
  get_time_step_size() const final;
 
  void
  set_current_time_step_size(double const & time_step_size) final;
 
protected:
  double
  get_scaling_factor_acceleration() const;
 
  double
  get_scaling_factor_velocity() const;
 
  double
  get_mid_time() const;
 
  /*
   * Computes the finite element vector corresponding to the *remainder* of the acceleration term,
   * which depends on past time step data only. Denoting the acceleration by a, the velocity by v
   * and the displacement by d, this function returns f1(a^n, v^n, d^n) in
   * D^2/Dt^2(d) = scaling_factor_acceleration * d^(n+1) + f1(a^n, v^n, d^n)
   */
  void
  compute_const_vector_acceleration_remainder(VectorType &       const_vector,
                                              VectorType const & displacement_n,
                                              VectorType const & velocity_n,
                                              VectorType const & acceleration_n) const;
 
  /*
   * Computes the finite element vector corresponding to the *remainder* of the velocity term, which
   * depends on past time step data only. Denoting the acceleration by a, the velocity by v and the
   * displacement by d, this function returns f2(a^n, v^n, d^n) in
   * D/Dt(d) = scaling_factor_velocity * d^(n+1) + f2(a^n, v^n, d^n).
   */
  void
  compute_const_vector_velocity_remainder(VectorType &       const_vector,
                                          VectorType const & displacement_n,
                                          VectorType const & velocity_n,
                                          VectorType const & acceleration_n) const;
 
  void
  update_displacement(VectorType & displacement_np, VectorType const & displacement_n) const;
 
  void
  update_velocity(VectorType &       velocity_np,
                  VectorType const & displacement_np,
                  VectorType const & displacement_n,
                  VectorType const & velocity_n,
                  VectorType const & acceleration_n) const;
 
  void
  update_acceleration(VectorType &       acceleration_np,
                      VectorType const & displacement_np,
                      VectorType const & displacement_n,
                      VectorType const & velocity_n,
                      VectorType const & acceleration_n) const;
 
private:
  void
  do_timestep_pre_solve(bool const print_header) final;
 
  void
  do_timestep_post_solve() final;
 
  virtual void
  prepare_vectors_for_next_timestep() = 0;
 
  /*
   * returns whether solver info has to be written in the current time step.
   */
  virtual bool
  print_solver_info() const = 0;
 
  double spectral_radius;
  double alpha_m;
  double alpha_f;
  double beta;
  double gamma;
 
  double time_step;
};
 
} // namespace ExaDG
 
#endif /* EXADG_TIME_INTEGRATION_TIME_INT_GEN_ALPHA_BASE_H_ */