scale_multigrid_solver_base.F90

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!-------------------------------------------------------------------------------
!> module FElib / Multigrid / Solver base
!!
!! @par Description
!!      A base module to provide a multigrid solver
!!
!! @author Yuta Kawai, Team SCALE
!<
!-------------------------------------------------------------------------------
#include "scaleFElib.h"
module scale_multigrid_solver_base
 
  !-----------------------------------------------------------------------------
  !
  !++ used modules
  !
  !
  use scale_precision
  use scale_io
  use scale_prc, only: prc_abort
 
  use scale_mesh_hierarchy_base, only: &
    meshhierarchybase, &
    pmg_finest_level => mesh_hierarchy_pmg_finest_level, &
    hmg_finest_level => mesh_hierarchy_hmg_finest_level, &
    mesh_hierarchy_type_pmg,                             &
    mesh_hierarchy_type_hmg
 
  !-----------------------------------------------------------------------------
  implicit none
  private
 
  !-----------------------------------------------------------------------------
  !
  !++ Public type & procedure
  ! 
 
  !> Base type for multigrid solver
  type, public :: multigridsolverbase
    integer :: current_p_lev  !< Current p-MG level
    integer :: current_h_lev  !< Current h-MG level
 
    integer :: vcyc_num_max
    real(rp) :: history_residual_l2_initial  !< Initial residual L2 norm
    real(rp) :: history_residual_max_initial !< Initial residual max norm
 
    real(rp) :: threshold_ratio_residual_l2  !< Threshold of decreasing ratio of residual for smoothing (L2 norm)
    real(rp) :: threshold_residual_l2  !< Residual threshold for smoothing (L2 norm)
    real(rp) :: threshold_residual_max !< Residual threshold for smoothing (max norm)
  contains
    procedure :: set_vcycle_parameter => multigridsolverbase_set_vcyc_param
    procedure :: is_converged => multigridsolverbase_is_converged
  end type multigridsolverbase
 
  public :: multigridsolverbase_init
  public :: multigridsolverbase_final
 
  !-----------------------------------------------------------------------------
  !
  !++ Public parameters & variables
  !
 
  !-----------------------------------------------------------------------------
  !
  !++ Private procedure
  !
  
  !-----------------------------------------------------------------------------
  !
  !++ Private parameters & variables
  !
contains
  !> Initialize a base object for multigrid solver
!OCL SERIAL
  subroutine multigridsolverbase_init( this, &
    mesh_hierarchy )
    implicit none
    class(multigridsolverbase), intent(inout) :: this
    class(meshhierarchybase), intent(in) :: mesh_hierarchy               !< Object to manage mesh hierarchy
    !-------------------------------------------------------------
    
    !-
    this%vcyc_num_max = 10
    return
  end subroutine multigridsolverbase_init
 
  !> Finalize a base object for multigrid solver
!OCL SERIAL
  subroutine multigridsolverbase_final(this)
    implicit none
    class(multigridsolverbase), intent(inout) :: this
    !-------------------------------------------------------------
    return
  end subroutine multigridsolverbase_final
 
  !> Set parameters for V-cycle
!OCL SERIAL
  subroutine multigridsolverbase_set_vcyc_param( this, &
    vcyc_num_max, threshold_ratio_residual_l2, threshold_residual_l2, threshold_residual_max )
    implicit none
    class(multigridsolverbase), intent(inout) :: this
    integer, intent(in) :: vcyc_num_max
    real(rp), intent(in) :: threshold_ratio_residual_l2
    real(rp), intent(in) :: threshold_residual_l2
    real(rp), intent(in) :: threshold_residual_max
    !-------------------------------------------------------------
    this%vcyc_num_max = vcyc_num_max
    this%threshold_ratio_residual_l2 = threshold_ratio_residual_l2
    this%threshold_residual_l2 = threshold_residual_l2
    this%threshold_residual_max = threshold_residual_max
    return
  end subroutine multigridsolverbase_set_vcyc_param
 
  !> Check convergence of multigrid solver
!OCL SERIAL
  function multigridsolverbase_is_converged( this, smoother ) result( conv_flag )
    use scale_multigrid_smoother_base, only: mgsmootherbase
    implicit none
    class(multigridsolverbase), intent(in) :: this
    class(mgsmootherbase), intent(in) :: smoother
    logical :: conv_flag
 
    real(rp) :: res_l2, res_max
    real(rp) :: res_decrease_ratio_l2
    !---------------------------------------------------------------------
 
    call smoother%Get_current_residual_statistics( res_l2, res_max )
    
    res_decrease_ratio_l2 = res_l2 / this%history_residual_l2_initial
    if ( ( res_decrease_ratio_l2 < this%threshold_ratio_residual_l2 ) &
          .or. (      res_l2 < this%threshold_residual_l2             &
                .and. res_max < this%threshold_residual_max )         ) then
      conv_flag = .true.
    else
      conv_flag = .false.
    end if
    return
  end function multigridsolverbase_is_converged  
 
end module scale_multigrid_solver_base