asymptotic_rankine.f90

PURE SUBROUTINE COMPUTE_ASYMPTOTIC_RANKINE_SOURCE(m, face_center, &
& face_area, s0, vs0)
  IMPLICIT NONE
  REAL :: pre
! Same as above, but always use the approximate aymptotic value.
! Inputs
  REAL(kind=8), DIMENSION(3), INTENT(IN) :: m
  REAL(kind=8), DIMENSION(3), INTENT(IN) :: face_center
  REAL(kind=8), INTENT(IN) :: face_area
! Outputs
  REAL(kind=8), INTENT(OUT) :: s0
  REAL(kind=8), DIMENSION(3), INTENT(OUT) :: vs0
! Local variables
  REAL(kind=pre) :: ro
  EXTERNAL NORM2
  INTEGER :: NORM2
  INTRINSIC REAL
  REAL :: zero
  REAL(kind=8), DIMENSION(3) :: arg1
! Distance from center of mass of the face to M.
  arg1(:) = m(1:3) - face_center(1:3)
  ro = NORM2(arg1(:))
  IF (ro .GT. REAL(1e-7, kind=pre)) THEN
! Asymptotic value if face far away from M
    s0 = face_area/ro
    vs0(1:3) = (face_center(1:3)-m)*s0/ro**2
  ELSE
! Singularity...
    s0 = zero
    vs0(1:3) = zero
  END IF
END SUBROUTINE COMPUTE_ASYMPTOTIC_RANKINE_SOURCE