neumann.f90

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module neumann
  use num_types, only : rp
  use bc, only : bc_t
  use, intrinsic :: iso_c_binding, only : c_ptr, c_null_ptr
  use utils, only : neko_error, nonlinear_index
  use coefs, only : coef_t
  use json_module, only : json_file
  use json_utils, only : json_get
  use math, only : cfill, copy, abscmp
  use vector, only: vector_t
  use neko_config, only : neko_bcknd_device
  use device_math, only : device_cfill, device_copy
  use device, only : device_memcpy, device_to_host
  use device_neumann, only : device_neumann_apply_scalar
  use time_state, only : time_state_t
  implicit none
  private
 
  type, public, extends(bc_t) :: neumann_t
     type(vector_t) :: flux_
     real(kind=rp), private :: init_flux_
     logical :: uniform_0 = .false.
   contains
     procedure, pass(this) :: apply_scalar => neumann_apply_scalar
     procedure, pass(this) :: apply_vector => neumann_apply_vector
     procedure, pass(this) :: apply_scalar_dev => neumann_apply_scalar_dev
     procedure, pass(this) :: apply_vector_dev => neumann_apply_vector_dev
     procedure, pass(this) :: init => neumann_init
     procedure, pass(this) :: init_from_components => &
          neumann_init_from_components
     procedure, pass(this) :: flux => neumann_flux
     procedure, pass(this) :: set_flux_scalar => neumann_set_flux_scalar
     procedure, pass(this) :: set_flux_array => neumann_set_flux_array
     generic :: set_flux => set_flux_scalar, set_flux_array
     procedure, pass(this) :: free => neumann_free
     procedure, pass(this) :: finalize => neumann_finalize
  end type neumann_t
 
contains
 
  subroutine neumann_init(this, coef, json)
    class(neumann_t), intent(inout), target :: this
    type(coef_t), target, intent(in) :: coef
    type(json_file), intent(inout) :: json
    real(kind=rp) :: flux
 
    call this%init_base(coef)
    this%strong = .false.
 
    call json_get(json, "flux", flux)
    this%init_flux_ = flux
  end subroutine neumann_init
 
  subroutine neumann_init_from_components(this, coef, flux)
    class(neumann_t), intent(inout), target :: this
    type(coef_t), intent(in) :: coef
    real(kind=rp), intent(in) :: flux
 
    call this%init_base(coef)
    this%init_flux_ = flux
  end subroutine neumann_init_from_components
 
  subroutine neumann_apply_scalar(this, x, n, time, strong)
    class(neumann_t), intent(inout) :: this
    integer, intent(in) :: n
    real(kind=rp), intent(inout), dimension(n) :: x
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    integer :: i, m, k, facet
    ! Store non-linear index
    integer :: idx(4)
    logical :: strong_
 
    if (present(strong)) then
       strong_ = strong
    else
       strong_ = .true.
    end if
 
    m = this%msk(0)
    if (.not. strong_) then
       do i = 1, m
          k = this%msk(i)
          facet = this%facet(i)
          idx = nonlinear_index(k, this%coef%Xh%lx, this%coef%Xh%lx,&
               this%coef%Xh%lx)
          select case (facet)
          case (1,2)
             x(k) = x(k) + &
                  this%flux_%x(i)*this%coef%area(idx(2), idx(3), facet, idx(4))
          case (3,4)
             x(k) = x(k) + &
                  this%flux_%x(i)*this%coef%area(idx(1), idx(3), facet, idx(4))
          case (5,6)
             x(k) = x(k) + &
                  this%flux_%x(i)*this%coef%area(idx(1), idx(2), facet, idx(4))
          end select
       end do
    end if
  end subroutine neumann_apply_scalar
 
  subroutine neumann_apply_vector(this, x, y, z, n, time, strong)
    class(neumann_t), intent(inout) :: this
    integer, intent(in) :: n
    real(kind=rp), intent(inout), dimension(n) :: x
    real(kind=rp), intent(inout), dimension(n) :: y
    real(kind=rp), intent(inout), dimension(n) :: z
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
 
    if (.not. this%uniform_0 .and. this%msk(0) .gt. 0) then
       call neko_error("Neumann bc not implemented for vectors")
    end if
  end subroutine neumann_apply_vector
 
  subroutine neumann_apply_scalar_dev(this, x_d, time, strong, strm)
    class(neumann_t), intent(inout), target :: this
    type(c_ptr), intent(inout) :: x_d
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    type(c_ptr), intent(inout) :: strm
    logical :: strong_
 
    if (present(strong)) then
       strong_ = strong
    else
       strong_ = .true.
    end if
 
    if (.not. this%uniform_0 .and. this%msk(0) .gt. 0 .and. &
        .not. strong_) then
       call device_neumann_apply_scalar(this%msk_d, this%facet_d, x_d, &
            this%flux_%x_d, this%coef%area_d, this%coef%Xh%lx, &
            size(this%msk), strm)
    end if
  end subroutine neumann_apply_scalar_dev
 
  subroutine neumann_apply_vector_dev(this, x_d, y_d, z_d, &
       time, strong, strm)
    class(neumann_t), intent(inout), target :: this
    type(c_ptr), intent(inout) :: x_d
    type(c_ptr), intent(inout) :: y_d
    type(c_ptr), intent(inout) :: z_d
    type(time_state_t), intent(in), optional :: time
    logical, intent(in), optional :: strong
    type(c_ptr), intent(inout) :: strm
 
    if (.not. this%uniform_0 .and. this%msk(0) .gt. 0) then
       call neko_error("Neumann bc not implemented for vectors.")
    end if
 
  end subroutine neumann_apply_vector_dev
 
  subroutine neumann_free(this)
    class(neumann_t), target, intent(inout) :: this
 
    call this%free_base()
 
  end subroutine neumann_free
 
  subroutine neumann_finalize(this, only_facets)
    class(neumann_t), target, intent(inout) :: this
    logical, optional, intent(in) :: only_facets
    integer :: i
 
    if (present(only_facets)) then
       if (only_facets .eqv. .false.) then
          call neko_error("For neumann_t, only_facets has to be true.")
       end if
    end if
 
    call this%finalize_base(.true.)
 
    call this%flux_%init(this%msk(0))
 
    this%flux_ = this%init_flux_
    this%uniform_0 = .true.
 
    do i = 1,this%msk(0)
       this%uniform_0 = abscmp(this%init_flux_, 0.0_rp) .and. this%uniform_0
    end do
  end subroutine neumann_finalize
 
  !This looks really sketchy IMO /Martin
  pure function neumann_flux(this) result(flux)
    class(neumann_t), intent(in) :: this
    real(kind=rp) :: flux(this%msk(0))
 
    flux = this%flux_%x
  end function neumann_flux
 
  subroutine neumann_set_flux_scalar(this, flux)
    class(neumann_t), intent(inout) :: this
    real(kind=rp), intent(in) :: flux
 
    this%flux_ = flux
    this%uniform_0 = abscmp(flux, 0.0_rp)
 
  end subroutine neumann_set_flux_scalar
 
  subroutine neumann_set_flux_array(this, flux)
    class(neumann_t), intent(inout) :: this
    type(vector_t), intent(in) :: flux
    integer :: i
 
    this%flux_ = flux
 
    ! We assume that passing a homogeneous array is so rare that it is not
    ! worth doing a check, which requires a loop over the flux values.
    ! Note that this routine can be called at each timestep, e.g. by wall
    ! models.
    this%uniform_0 = .false.
 
  end subroutine neumann_set_flux_array
 
end module neumann