neumann.f90

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module neumann
  use num_types
  use bc, only : bc_t
  use, intrinsic :: iso_c_binding, only : c_ptr
  use utils, only : neko_error, nonlinear_index
  use coefs, only : coef_t
  use math, only : cfill
  implicit none
  private
 
  type, public, extends(bc_t) :: neumann_t
     real(kind=rp), allocatable, private :: flux_(:)
   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) :: finalize_neumann => neumann_finalize_neumann
     procedure, pass(this) :: flux => neumann_flux
     procedure, pass(this) :: free => neumann_free
  end type neumann_t
 
contains
 
  subroutine neumann_apply_scalar(this, x, n, t, tstep)
    class(neumann_t), intent(inout) :: this
    integer, intent(in) :: n
    real(kind=rp), intent(inout),  dimension(n) :: x
    real(kind=rp), intent(in), optional :: t
    integer, intent(in), optional :: tstep
    integer :: i, m, k, facet
    ! Store non-linear index
    integer :: idx(4)
 
    m = this%msk(0)
    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_(i)*this%coef%area(idx(2), idx(3), facet, idx(4))
       case(3,4)
          x(k) = x(k) + this%flux_(i)*this%coef%area(idx(1), idx(3), facet, idx(4))
       case(5,6)
          x(k) = x(k) + this%flux_(i)*this%coef%area(idx(1), idx(2), facet, idx(4))
       end select
    end do
  end subroutine neumann_apply_scalar
 
  subroutine neumann_apply_vector(this, x, y, z, n, t, tstep)
    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
    real(kind=rp), intent(in), optional :: t
    integer, intent(in), optional :: tstep
 
    call neko_error("Neumann bc not implemented for vectors")
 
  end subroutine neumann_apply_vector
 
  subroutine neumann_apply_scalar_dev(this, x_d, t, tstep)
    class(neumann_t), intent(inout), target :: this
    type(c_ptr) :: x_d
    real(kind=rp), intent(in), optional :: t
    integer, intent(in), optional :: tstep
 
    call neko_error("Neumann bc not implemented on the device")
 
  end subroutine neumann_apply_scalar_dev
 
  subroutine neumann_apply_vector_dev(this, x_d, y_d, z_d, t, tstep)
    class(neumann_t), intent(inout), target :: this
    type(c_ptr) :: x_d
    type(c_ptr) :: y_d
    type(c_ptr) :: z_d
    real(kind=rp), intent(in), optional :: t
    integer, intent(in), optional :: tstep
 
    call neko_error("Neumann bc not implemented on the device")
 
  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
 
  pure function neumann_flux(this) result(flux)
    class(neumann_t), intent(in) :: this
    real(kind=rp) :: flux(this%msk(0))
 
    flux = this%flux_
  end function neumann_flux
 
  subroutine neumann_finalize_neumann(this, flux)
    class(neumann_t), intent(inout) :: this
    real(kind=rp), intent(in) :: flux
 
    call this%finalize()
    allocate(this%flux_(this%msk(0)))
 
    call cfill(this%flux_, flux, this%msk(0))
  end subroutine neumann_finalize_neumann
 
end module neumann