Changeset 2372 for palm/trunk/SOURCE/init_pegrid.f90

Timestamp:

Aug 25, 2017 12:37:32 PM (7 years ago)

Author:

sward

Message:

y_shift for periodic boundary conditions

File:

• palm/trunk/SOURCE/init_pegrid.f90 (modified) (4 diffs)

palm/trunk/SOURCE/init_pegrid.f90

@@ -25 +25 @@
 ! -----------------
 ! $Id$
+! Shifted cyclic boundary conditions implemented
+! 
+! 2365 2017-08-21 14:59:59Z kanani
 ! Vertical nesting implemented (SadiqHuq)
 ! 
@@ -206 +209 @@
                psolver, outflow_l, outflow_n, outflow_r, outflow_s,            &
                outflow_source_plane, recycling_width, scalar_advec,            &
-               subdomain_size, turbulent_outflow
+               subdomain_size, turbulent_outflow, y_shift
 
     USE grid_variables,                                                        &
@@ -271 +274 @@
     INTEGER(iwp), DIMENSION(:), ALLOCATABLE ::  nysf    !<
 
-    INTEGER(iwp), DIMENSION(2) :: pdims_remote          !<
+    INTEGER(iwp), DIMENSION(2) ::  pdims_remote         !<
+    INTEGER(iwp)               ::  lcoord(2)            !< PE coordinates of left neighbor along x and y
+    INTEGER(iwp)               ::  rcoord(2)            !< PE coordinates of right neighbor along x and y
 
 !
@@ -339 +344 @@
     CALL MPI_CART_SHIFT( comm2d, 0, 1, pleft, pright, ierr )
     CALL MPI_CART_SHIFT( comm2d, 1, 1, psouth, pnorth, ierr )
+
+!
+!-- In case of cyclic boundary conditions, a y-shift at the boundaries in
+!-- x-direction can be introduced via parameter y_shift. The shift is done
+!-- by modifying the processor grid in such a way that processors located
+!-- at the x-boundary communicate across it to processors with y-coordinate
+!-- shifted by y_shift relative to their own. This feature can not be used
+!-- in combination with an fft pressure solver. It has been implemented to
+!-- counter the effect of streak structures in case of cyclic boundary
+!-- conditions. For a description of these see Munters
+!-- (2016; dx.doi.org/10.1063/1.4941912)
+!--
+!-- Get coordinates of left and right neighbor on PE grid
+    IF ( y_shift /= 0 ) THEN
+
+       IF ( bc_lr /= 'cyclic'  .OR.  bc_ns /= 'cyclic' )  THEN
+          message_string = 'y_shift /= 0 is only allowed for cyclic ' //       &
+                           'boundary conditions in both directions '
+          CALL message( 'check_parameters', 'PA0467', 1, 2, 0, 6, 0 )
+       ENDIF
+       IF ( TRIM( psolver ) /= 'multigrid' .AND.                               &
+            TRIM( psolver ) /= 'multigrid_noopt')                              &
+       THEN
+          message_string = 'y_shift /= 0 requires a multigrid pressure solver '
+          CALL message( 'check_parameters', 'PA0468', 1, 2, 0, 6, 0 )
+       ENDIF
+
+       CALL MPI_CART_COORDS( comm2d, pright, ndim, rcoord, ierr )
+       CALL MPI_CART_COORDS( comm2d, pleft, ndim, lcoord, ierr )
+
+!
+!--    If the x(y)-coordinate of the right (left) neighbor is smaller (greater)
+!--    than that of the calling process, then the calling process is located on
+!--    the right (left) boundary of the processor grid. In that case,
+!--    the y-coordinate of that neighbor is increased (decreased) by y_shift.
+!--    The rank of the process with that coordinate is then inquired and the
+!--    neighbor rank for MPI_SENDRECV, pright (pleft) is set to it.
+!--    In this way, the calling process receives a new right (left) neighbor
+!--    for all future MPI_SENDRECV calls. That neighbor has a y-coordinate
+!--    of y+(-)y_shift, where y is the original right (left) neighbor's
+!--    y-coordinate. The modulo-operation ensures that if the neighbor's
+!--    y-coordinate exceeds the grid-boundary, it will be relocated to
+!--    the opposite part of the grid cyclicly.
+       IF ( rcoord(1) < pcoord(1) ) THEN
+          rcoord(2) = MODULO( rcoord(2) + y_shift, pdims(2) )
+          CALL MPI_CART_RANK( comm2d, rcoord, pright, ierr )
+       ENDIF
+
+       IF ( lcoord(1) > pcoord(1) ) THEN
+          lcoord(2) = MODULO( lcoord(2) - y_shift, pdims(2) )
+          CALL MPI_CART_RANK( comm2d, lcoord, pleft, ierr )
+       ENDIF
+    ENDIF
 
 !