Merge pull request #14901 from johodges/master

FDS Source: add mpi barrier between INITIALIZE_BACK_WALL_EXCHANGE calls

Author: mcgratta

Source/main.f90

@@ -276,6 +276,7 @@ PROGRAM FDS
 ! done, there is no need to exchange all HT3D cells. The second call reduces the size of the exchange arrays.
 
 CALL INITIALIZE_BACK_WALL_EXCHANGE(1)
+CALL MPI_BARRIER(MPI_COMM_WORLD,IERR)
 CALL INITIALIZE_BACK_WALL_EXCHANGE(2)
 
 IF (MY_RANK==0 .AND. VERBOSE) CALL VERBOSE_PRINTOUT('Completed INITIALIZE_BACK_WALL_EXCHANGE')