upwind1.f90 Source File

!> @file upwind1.f90
!> @brief First-order upwind reconstruction scheme.

module upwind1
  use precision, only: wp
  implicit none
  private

  public :: upwind1_reconstruct

contains

  ! ---------------------------------------------------------------------------
  !> First-order upwind reconstruction.
  !!
  !! Returns the centre element of the stencil, which corresponds to the
  !! cell immediately adjacent to the interface for both the left-biased
  !! (positive) and right-biased (negative) stencils assembled by
  !! spatial_discretization.
  !!
  !! @param[in]  f_stencil  Split flux stencil (neq x stencil_width)
  !! @param[out] f_hat      Upwind flux at the interface
  ! ---------------------------------------------------------------------------
  pure subroutine upwind1_reconstruct(f_stencil, f_hat)
    real(wp), intent(in) :: f_stencil(:, :)
    real(wp), intent(out) :: f_hat(:)

    f_hat = f_stencil(:, (size(f_stencil, 2) + 1) / 2)
  end subroutine upwind1_reconstruct

end module upwind1