grans_obj_PrepareSolverBCS Subroutine

    subroutine grans_obj_PrepareSolverBCS(this)
      !> Prepares the boundary conditions used by GRANS.
      ! Note that the only boundary conditions required by GRANS
      ! are those in connection with the volume fraction Poisson equations.
      ! This subroutine reads pre-existing BCS file on disk.
      ! It adds additional boundary conditions for ibF, ibN, and ibS based
      ! on the specified boundary conditions for ibVF. If no Dirichlet
      ! conditions are given for ibVF, it marks the volume fraction Poisson
      ! equation as singular.
      implicit none
      class(grans_obj), intent(inout) :: this                                  !! GRANS solver
      ! Work variables
      real(wp)  :: time
      integer   :: iter
      integer   :: n
      real(wp), pointer   :: BCVal(:,:,:)
      character(len=str64):: filename
      logical             :: ibVFDirichlet
      logical             :: buffL

      call this%parser%Get('BC file ',  filename, default= 'bcs' )

      ! Initialize and read boundary conditions
      call this%bcs%Initialize(this%block,this%parallel)
      call this%bcs%Read(iter,time,filename)

      associate (bcs => this%bcs)
        if (this%use_RP .or. this%use_IB) then

          ! Check boundary conditions for ibVF
          ibVFDirichlet = .false.
          do n=1,bcs%count
            ! Check Whether we have a BC for this variable on this region
            if (.not.bcs%CheckBCExists(bcs%region(n)%name,'ibVF')) cycle

            select case (bcs%GetBCType(bcs%region(n)%name,'ibVF'))
            case (BC_DIRICHLET)
              ! Found Dirichlet condition
              ibVFDirichlet = .true.

              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibS' )
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibN1')
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibN2')
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibN3')
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibF1')
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibF2')
              call bcs%SetBC(bcs%region(n)%name,BC_DIRICHLET,'ibF3')

              call bcs%GetBCPointer(bcs%region(n)%name,'ibS',  BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibN1', BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibN2', BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibN3', BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibF1', BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibF2', BCVal); BCVal = 0.0_wp
              call bcs%GetBCPointer(bcs%region(n)%name,'ibF3', BCVal); BCVal = 0.0_wp
            case (BC_NEUMANN)
            case (BC_SYMMETRY)
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibS' )
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibN1')
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibN2')
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibN3')
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibF1')
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibF2')
              call bcs%SetBC(bcs%region(n)%name,BC_SYMMETRY,'ibF3')
            end select
          end do

          call this%parallel%Lor(ibVFDirichlet,buffL); ibVFDirichlet=buffL

          ! Determine if we need to apply volume fraction corrections
          if (.not.ibVFDirichlet) this%singularVF = .true.
        end if
      end associate

      return
    end subroutine grans_obj_PrepareSolverBCS