SUBROUTINE inflow_turbulence

!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2014 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: inflow_turbulence.f90 1310 2014-03-14 08:01:56Z fricke $
!
! 1092 2013-02-02 11:24:22Z raasch
! unused variables removed
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 709 2011-03-30 09:31:40Z raasch
! formatting adjustments
!
! 667 2010-12-23 12:06:00Z suehring/gryschka
! Using nbgp recycling planes for a better resolution of the turbulent flow 
! near the inflow.
!
! 622 2010-12-10 08:08:13Z raasch
! optional barriers included in order to speed up collective operations
!
! 222 2009-01-12 16:04:16Z letzel
! Bugfix for nonparallel execution
!
! Initial version (2008/03/07)
!
! Description:
! ------------
! Imposing turbulence at the respective inflow using the turbulence
! recycling method of Kataoka and Mizuno (2002).
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE control_parameters
    USE cpulog
    USE grid_variables
    USE indices
    USE interfaces
    USE pegrid


    IMPLICIT NONE

    INTEGER ::  i, j, k, l, ngp_ifd, ngp_pr

    REAL, DIMENSION(nzb:nzt+1,5,nbgp) ::  avpr, avpr_l
    REAL, DIMENSION(nzb:nzt+1,nysg:nyng,5,nbgp) ::  inflow_dist

    CALL cpu_log( log_point(40), 'inflow_turbulence', 'start' )

!
!-- Carry out spanwise averaging in the recycling plane
    avpr_l = 0.0
    ngp_pr = ( nzt - nzb + 2 ) * 5 * nbgp
    ngp_ifd = ngp_pr * ( nyn - nys + 1 + 2 * nbgp )

!
!-- First, local averaging within the recycling domain
    i = recycling_plane

#if defined( __parallel )
    IF ( myidx == id_recycling )  THEN
       
       DO  l = 1, nbgp
          DO  j = nys, nyn
             DO  k = nzb, nzt + 1

                avpr_l(k,1,l) = avpr_l(k,1,l) + u(k,j,i)
                avpr_l(k,2,l) = avpr_l(k,2,l) + v(k,j,i)
                avpr_l(k,3,l) = avpr_l(k,3,l) + w(k,j,i)
                avpr_l(k,4,l) = avpr_l(k,4,l) + pt(k,j,i)
                avpr_l(k,5,l) = avpr_l(k,5,l) + e(k,j,i)

             ENDDO
          ENDDO
          i = i + 1
       ENDDO

    ENDIF
!
!-- Now, averaging over all PEs
    IF ( collective_wait )  CALL MPI_BARRIER( comm2d, ierr )
    CALL MPI_ALLREDUCE( avpr_l(nzb,1,1), avpr(nzb,1,1), ngp_pr, MPI_REAL, &
                        MPI_SUM, comm2d, ierr )

#else
    DO  l = 1, nbgp
       DO  j = nys, nyn
          DO  k = nzb, nzt + 1

             avpr_l(k,1,l) = avpr_l(k,1,l) + u(k,j,i)
             avpr_l(k,2,l) = avpr_l(k,2,l) + v(k,j,i)
             avpr_l(k,3,l) = avpr_l(k,3,l) + w(k,j,i)
             avpr_l(k,4,l) = avpr_l(k,4,l) + pt(k,j,i)
             avpr_l(k,5,l) = avpr_l(k,5,l) + e(k,j,i)

          ENDDO
       ENDDO
       i = i + 1 
    ENDDO
    
    avpr = avpr_l
#endif

    avpr = avpr / ( ny + 1 )
!
!-- Calculate the disturbances at the recycling plane
    i = recycling_plane

#if defined( __parallel )
    IF ( myidx == id_recycling )  THEN
       DO  l = 1, nbgp
          DO  j = nysg, nyng
             DO  k = nzb, nzt + 1

                inflow_dist(k,j,1,l) = u(k,j,i+1) - avpr(k,1,l)
                inflow_dist(k,j,2,l) = v(k,j,i)   - avpr(k,2,l)
                inflow_dist(k,j,3,l) = w(k,j,i)   - avpr(k,3,l)
                inflow_dist(k,j,4,l) = pt(k,j,i)  - avpr(k,4,l)
                inflow_dist(k,j,5,l) = e(k,j,i)   - avpr(k,5,l)
              
            ENDDO
          ENDDO
          i = i + 1
       ENDDO

    ENDIF
#else
    DO  l = 1, nbgp
       DO  j = nysg, nyng
          DO  k = nzb, nzt+1

             inflow_dist(k,j,1,l) = u(k,j,i+1) - avpr(k,1,l)
             inflow_dist(k,j,2,l) = v(k,j,i)   - avpr(k,2,l)
             inflow_dist(k,j,3,l) = w(k,j,i)   - avpr(k,3,l)
             inflow_dist(k,j,4,l) = pt(k,j,i)  - avpr(k,4,l)
             inflow_dist(k,j,5,l) = e(k,j,i)   - avpr(k,5,l)
              
          ENDDO
       ENDDO
       i = i + 1
    ENDDO
#endif

!
!-- For parallel runs, send the disturbances to the respective inflow PE
#if defined( __parallel )
    IF ( myidx == id_recycling  .AND.  myidx /= id_inflow )  THEN

       CALL MPI_SEND( inflow_dist(nzb,nysg,1,1), ngp_ifd, MPI_REAL, &
                      id_inflow, 1, comm1dx, ierr )

    ELSEIF ( myidx /= id_recycling  .AND.  myidx == id_inflow )  THEN

       inflow_dist = 0.0
       CALL MPI_RECV( inflow_dist(nzb,nysg,1,1), ngp_ifd, MPI_REAL, &
                      id_recycling, 1, comm1dx, status, ierr )

    ENDIF
#endif

!
!-- Add the disturbance at the inflow
    IF ( nxl == 0 )  THEN

       DO  j = nysg, nyng
          DO  k = nzb, nzt + 1

              u(k,j,-nbgp+1:0) = mean_inflow_profiles(k,1) + &
                           inflow_dist(k,j,1,1:nbgp) * inflow_damping_factor(k)
              v(k,j,-nbgp:-1)  = mean_inflow_profiles(k,2) + &
                           inflow_dist(k,j,2,1:nbgp) * inflow_damping_factor(k)
              w(k,j,-nbgp:-1)  =                             &
                           inflow_dist(k,j,3,1:nbgp) * inflow_damping_factor(k)
              pt(k,j,-nbgp:-1) = mean_inflow_profiles(k,4) + &
                           inflow_dist(k,j,4,1:nbgp) * inflow_damping_factor(k)
              e(k,j,-nbgp:-1)  = mean_inflow_profiles(k,5) + &
                           inflow_dist(k,j,5,1:nbgp) * inflow_damping_factor(k)
              e(k,j,-nbgp:-1)  = MAX( e(k,j,-nbgp:-1), 0.0 )

          ENDDO
       ENDDO

    ENDIF

    CALL cpu_log( log_point(40), 'inflow_turbulence', 'stop' )


 END SUBROUTINE inflow_turbulence