| 1 | SUBROUTINE timestep |
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| 2 | |
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| 3 | !--------------------------------------------------------------------------------! |
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| 4 | ! This file is part of PALM. |
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| 5 | ! |
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| 6 | ! PALM is free software: you can redistribute it and/or modify it under the terms |
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| 7 | ! of the GNU General Public License as published by the Free Software Foundation, |
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| 8 | ! either version 3 of the License, or (at your option) any later version. |
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| 9 | ! |
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| 10 | ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY |
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| 11 | ! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR |
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| 12 | ! A PARTICULAR PURPOSE. See the GNU General Public License for more details. |
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| 13 | ! |
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| 14 | ! You should have received a copy of the GNU General Public License along with |
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| 15 | ! PALM. If not, see <http://www.gnu.org/licenses/>. |
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| 16 | ! |
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| 17 | ! Copyright 1997-2012 Leibniz University Hannover |
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| 18 | !--------------------------------------------------------------------------------! |
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| 19 | ! |
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| 20 | ! Current revisions: |
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| 21 | ! ------------------ |
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| 22 | ! |
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| 23 | ! |
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| 24 | ! Former revisions: |
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| 25 | ! ----------------- |
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| 26 | ! $Id: timestep.f90 1258 2013-11-08 16:09:09Z heinze $ |
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| 27 | ! |
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| 28 | ! 1257 2013-11-08 15:18:40Z raasch |
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| 29 | ! openacc porting |
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| 30 | ! bugfix for calculation of advective timestep in case of vertically stretched |
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| 31 | ! grids |
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| 32 | ! |
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| 33 | ! 1092 2013-02-02 11:24:22Z raasch |
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| 34 | ! unused variables removed |
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| 35 | ! |
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| 36 | ! 1053 2012-11-13 17:11:03Z hoffmann |
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| 37 | ! timestep is reduced in two-moment cloud scheme according to the maximum |
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| 38 | ! terminal velocity of rain drops |
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| 39 | ! |
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| 40 | ! 1036 2012-10-22 13:43:42Z raasch |
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| 41 | ! code put under GPL (PALM 3.9) |
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| 42 | ! |
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| 43 | ! 1001 2012-09-13 14:08:46Z raasch |
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| 44 | ! all actions concerning leapfrog scheme removed |
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| 45 | ! |
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| 46 | ! 978 2012-08-09 08:28:32Z fricke |
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| 47 | ! restriction of the outflow damping layer in the diffusion criterion removed |
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| 48 | ! |
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| 49 | ! 866 2012-03-28 06:44:41Z raasch |
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| 50 | ! bugfix for timestep calculation in case of Galilei transformation, |
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| 51 | ! special treatment in case of mirror velocity boundary condition removed |
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| 52 | ! |
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| 53 | ! 707 2011-03-29 11:39:40Z raasch |
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| 54 | ! bc_lr/ns replaced by bc_lr/ns_cyc |
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| 55 | ! |
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| 56 | ! 667 2010-12-23 12:06:00Z suehring/gryschka |
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| 57 | ! Exchange of terminate_coupled between ocean and atmosphere via PE0 |
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| 58 | ! Minimum grid spacing dxyz2_min(k) is now calculated using dzw instead of dzu |
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| 59 | ! |
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| 60 | ! 622 2010-12-10 08:08:13Z raasch |
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| 61 | ! optional barriers included in order to speed up collective operations |
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| 62 | ! |
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| 63 | ! 343 2009-06-24 12:59:09Z maronga |
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| 64 | ! Additional timestep criterion in case of simulations with plant canopy |
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| 65 | ! Output of messages replaced by message handling routine. |
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| 66 | ! |
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| 67 | ! 222 2009-01-12 16:04:16Z letzel |
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| 68 | ! Implementation of a MPI-1 Coupling: replaced myid with target_id |
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| 69 | ! Bugfix for nonparallel execution |
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| 70 | ! |
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| 71 | ! 108 2007-08-24 15:10:38Z letzel |
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| 72 | ! modifications to terminate coupled runs |
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| 73 | ! |
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| 74 | ! RCS Log replace by Id keyword, revision history cleaned up |
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| 75 | ! |
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| 76 | ! Revision 1.21 2006/02/23 12:59:44 raasch |
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| 77 | ! nt_anz renamed current_timestep_number |
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| 78 | ! |
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| 79 | ! Revision 1.1 1997/08/11 06:26:19 raasch |
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| 80 | ! Initial revision |
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| 81 | ! |
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| 82 | ! |
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| 83 | ! Description: |
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| 84 | ! ------------ |
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| 85 | ! Compute the time step under consideration of the FCL and diffusion criterion. |
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| 86 | !------------------------------------------------------------------------------! |
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| 87 | |
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| 88 | USE arrays_3d |
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| 89 | USE cloud_parameters |
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| 90 | USE control_parameters |
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| 91 | USE cpulog |
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| 92 | USE grid_variables |
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| 93 | USE indices |
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| 94 | USE interfaces |
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| 95 | USE pegrid |
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| 96 | USE statistics |
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| 97 | |
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| 98 | IMPLICIT NONE |
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| 99 | |
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| 100 | INTEGER :: i, j, k |
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| 101 | |
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| 102 | REAL :: div, dt_diff, dt_diff_l, dt_plant_canopy, dt_plant_canopy_l, & |
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| 103 | dt_plant_canopy_u, dt_plant_canopy_v, dt_plant_canopy_w, & |
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| 104 | dt_u, dt_u_l, dt_v, dt_v_l, dt_w, dt_w_l, u_gtrans_l, u_max_l, & |
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| 105 | u_min_l, value, v_gtrans_l, v_max_l, v_min_l, w_max_l, w_min_l |
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| 106 | |
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| 107 | REAL, DIMENSION(2) :: uv_gtrans, uv_gtrans_l |
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| 108 | REAL, DIMENSION(3) :: reduce, reduce_l |
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| 109 | REAL, DIMENSION(nzb+1:nzt) :: dxyz2_min |
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| 110 | |
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| 111 | |
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| 112 | |
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| 113 | CALL cpu_log( log_point(12), 'calculate_timestep', 'start' ) |
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| 114 | |
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| 115 | ! |
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| 116 | !-- In case of Galilei-transform not using the geostrophic wind as translation |
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| 117 | !-- velocity, compute the volume-averaged horizontal velocity components, which |
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| 118 | !-- will then be subtracted from the horizontal wind for the time step and |
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| 119 | !-- horizontal advection routines. |
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| 120 | IF ( galilei_transformation .AND. .NOT. use_ug_for_galilei_tr ) THEN |
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| 121 | IF ( flow_statistics_called ) THEN |
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| 122 | ! |
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| 123 | !-- Horizontal averages already existent, just need to average them |
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| 124 | !-- vertically. |
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| 125 | u_gtrans = 0.0 |
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| 126 | v_gtrans = 0.0 |
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| 127 | DO k = nzb+1, nzt |
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| 128 | u_gtrans = u_gtrans + hom(k,1,1,0) |
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| 129 | v_gtrans = v_gtrans + hom(k,1,2,0) |
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| 130 | ENDDO |
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| 131 | u_gtrans = u_gtrans / REAL( nzt - nzb ) |
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| 132 | v_gtrans = v_gtrans / REAL( nzt - nzb ) |
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| 133 | ELSE |
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| 134 | ! |
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| 135 | !-- Averaging over the entire model domain. |
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| 136 | u_gtrans_l = 0.0 |
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| 137 | v_gtrans_l = 0.0 |
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| 138 | !$acc parallel present( u, v ) |
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| 139 | DO i = nxl, nxr |
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| 140 | DO j = nys, nyn |
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| 141 | DO k = nzb+1, nzt |
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| 142 | u_gtrans_l = u_gtrans_l + u(k,j,i) |
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| 143 | v_gtrans_l = v_gtrans_l + v(k,j,i) |
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| 144 | ENDDO |
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| 145 | ENDDO |
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| 146 | ENDDO |
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| 147 | !$acc end parallel |
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| 148 | uv_gtrans_l(1) = u_gtrans_l / REAL( (nxr-nxl+1)*(nyn-nys+1)*(nzt-nzb) ) |
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| 149 | uv_gtrans_l(2) = v_gtrans_l / REAL( (nxr-nxl+1)*(nyn-nys+1)*(nzt-nzb) ) |
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| 150 | #if defined( __parallel ) |
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| 151 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 152 | CALL MPI_ALLREDUCE( uv_gtrans_l, uv_gtrans, 2, MPI_REAL, MPI_SUM, & |
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| 153 | comm2d, ierr ) |
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| 154 | u_gtrans = uv_gtrans(1) / REAL( numprocs ) |
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| 155 | v_gtrans = uv_gtrans(2) / REAL( numprocs ) |
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| 156 | #else |
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| 157 | u_gtrans = uv_gtrans_l(1) |
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| 158 | v_gtrans = uv_gtrans_l(2) |
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| 159 | #endif |
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| 160 | ENDIF |
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| 161 | ENDIF |
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| 162 | |
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| 163 | ! |
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| 164 | !-- Determine the maxima of the velocity components, including their |
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| 165 | !-- grid index positions. |
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| 166 | #if defined( __openacc ) |
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| 167 | IF ( dt_fixed ) THEN ! otherwise do it further below for better cache usage |
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| 168 | u_max_l = -999999.9 |
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| 169 | u_min_l = 999999.9 |
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| 170 | v_max_l = -999999.9 |
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| 171 | v_min_l = 999999.9 |
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| 172 | w_max_l = -999999.9 |
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| 173 | w_min_l = 999999.9 |
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| 174 | !$acc parallel present( u, v, w ) |
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| 175 | DO i = nxl, nxr |
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| 176 | DO j = nys, nyn |
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| 177 | DO k = nzb+1, nzt |
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| 178 | u_max_l = MAX( u_max_l, u(k,j,i) ) |
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| 179 | u_min_l = MIN( u_min_l, u(k,j,i) ) |
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| 180 | v_max_l = MAX( v_max_l, v(k,j,i) ) |
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| 181 | v_min_l = MIN( v_min_l, v(k,j,i) ) |
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| 182 | w_max_l = MAX( w_max_l, w(k,j,i) ) |
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| 183 | w_min_l = MIN( w_min_l, w(k,j,i) ) |
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| 184 | ENDDO |
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| 185 | ENDDO |
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| 186 | ENDDO |
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| 187 | !$acc end parallel |
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| 188 | #if defined( __parallel ) |
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| 189 | reduce_l(1) = u_max_l |
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| 190 | reduce_l(2) = v_max_l |
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| 191 | reduce_l(3) = w_max_l |
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| 192 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 193 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MAX, comm2d, ierr ) |
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| 194 | u_max = reduce(1) |
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| 195 | v_max = reduce(2) |
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| 196 | w_max = reduce(3) |
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| 197 | reduce_l(1) = u_min_l |
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| 198 | reduce_l(2) = v_min_l |
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| 199 | reduce_l(3) = w_min_l |
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| 200 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 201 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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| 202 | IF ( ABS( reduce(1) ) > u_max ) u_max = reduce(1) |
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| 203 | IF ( ABS( reduce(2) ) > v_max ) v_max = reduce(2) |
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| 204 | IF ( ABS( reduce(3) ) > w_max ) w_max = reduce(3) |
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| 205 | #else |
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| 206 | IF ( ABS( u_min_l ) > u_max_l ) THEN |
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| 207 | u_max = u_min_l |
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| 208 | ELSE |
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| 209 | u_max = u_max_l |
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| 210 | ENDIF |
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| 211 | IF ( ABS( v_min_l ) > v_max_l ) THEN |
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| 212 | v_max = v_min_l |
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| 213 | ELSE |
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| 214 | v_max = v_max_l |
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| 215 | ENDIF |
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| 216 | IF ( ABS( w_min_l ) > w_max_l ) THEN |
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| 217 | w_max = w_min_l |
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| 218 | ELSE |
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| 219 | w_max = w_max_l |
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| 220 | ENDIF |
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| 221 | #endif |
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| 222 | ENDIF |
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| 223 | #else |
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| 224 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, u, 'abs', 0.0, & |
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| 225 | u_max, u_max_ijk ) |
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| 226 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, v, 'abs', 0.0, & |
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| 227 | v_max, v_max_ijk ) |
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| 228 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, w, 'abs', 0.0, & |
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| 229 | w_max, w_max_ijk ) |
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| 230 | #endif |
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| 231 | |
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| 232 | IF ( .NOT. dt_fixed ) THEN |
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| 233 | #if defined( __openacc ) |
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| 234 | ! |
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| 235 | !-- Variable time step: |
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| 236 | !-- Calculate the maximum time step according to the CFL-criterion, |
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| 237 | !-- individually for each velocity component |
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| 238 | dt_u_l = 999999.9 |
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| 239 | dt_v_l = 999999.9 |
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| 240 | dt_w_l = 999999.9 |
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| 241 | u_max_l = -999999.9 |
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| 242 | u_min_l = 999999.9 |
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| 243 | v_max_l = -999999.9 |
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| 244 | v_min_l = 999999.9 |
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| 245 | w_max_l = -999999.9 |
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| 246 | w_min_l = 999999.9 |
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| 247 | !$acc parallel loop collapse(3) present( u, v, w ) |
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| 248 | DO i = nxl, nxr |
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| 249 | DO j = nys, nyn |
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| 250 | DO k = nzb+1, nzt |
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| 251 | dt_u_l = MIN( dt_u_l, ( dx / ( ABS( u(k,j,i) - u_gtrans ) + 1.0E-10 ) ) ) |
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| 252 | dt_v_l = MIN( dt_v_l, ( dy / ( ABS( v(k,j,i) - v_gtrans ) + 1.0E-10 ) ) ) |
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| 253 | dt_w_l = MIN( dt_w_l, ( dzu(k) / ( ABS( w(k,j,i) ) + 1.0E-10 ) ) ) |
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| 254 | u_max_l = MAX( u_max_l, u(k,j,i) ) |
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| 255 | u_min_l = MIN( u_min_l, u(k,j,i) ) |
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| 256 | v_max_l = MAX( v_max_l, v(k,j,i) ) |
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| 257 | v_min_l = MIN( v_min_l, v(k,j,i) ) |
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| 258 | w_max_l = MAX( w_max_l, w(k,j,i) ) |
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| 259 | w_min_l = MIN( w_min_l, w(k,j,i) ) |
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| 260 | ENDDO |
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| 261 | ENDDO |
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| 262 | ENDDO |
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| 263 | !$acc end parallel |
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| 264 | |
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| 265 | #if defined( __parallel ) |
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| 266 | reduce_l(1) = dt_u_l |
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| 267 | reduce_l(2) = dt_v_l |
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| 268 | reduce_l(3) = dt_w_l |
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| 269 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 270 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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| 271 | dt_u = reduce(1) |
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| 272 | dt_v = reduce(2) |
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| 273 | dt_w = reduce(3) |
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| 274 | |
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| 275 | reduce_l(1) = u_max_l |
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| 276 | reduce_l(2) = v_max_l |
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| 277 | reduce_l(3) = w_max_l |
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| 278 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 279 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MAX, comm2d, ierr ) |
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| 280 | u_max = reduce(1) |
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| 281 | v_max = reduce(2) |
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| 282 | w_max = reduce(3) |
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| 283 | reduce_l(1) = u_min_l |
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| 284 | reduce_l(2) = v_min_l |
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| 285 | reduce_l(3) = w_min_l |
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| 286 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 287 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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| 288 | IF ( ABS( reduce(1) ) > u_max ) u_max = reduce(1) |
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| 289 | IF ( ABS( reduce(2) ) > v_max ) v_max = reduce(2) |
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| 290 | IF ( ABS( reduce(3) ) > w_max ) w_max = reduce(3) |
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| 291 | #else |
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| 292 | dt_u = dt_u_l |
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| 293 | dt_v = dt_v_l |
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| 294 | dt_w = dt_w_l |
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| 295 | |
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| 296 | IF ( ABS( u_min_l ) > u_max_l ) THEN |
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| 297 | u_max = u_min_l |
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| 298 | ELSE |
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| 299 | u_max = u_max_l |
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| 300 | ENDIF |
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| 301 | IF ( ABS( v_min_l ) > v_max_l ) THEN |
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| 302 | v_max = v_min_l |
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| 303 | ELSE |
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| 304 | v_max = v_max_l |
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| 305 | ENDIF |
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| 306 | IF ( ABS( w_min_l ) > w_max_l ) THEN |
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| 307 | w_max = w_min_l |
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| 308 | ELSE |
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| 309 | w_max = w_max_l |
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| 310 | ENDIF |
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| 311 | #endif |
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| 312 | |
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| 313 | #else |
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| 314 | ! |
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| 315 | !-- Variable time step: |
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| 316 | !-- Calculate the maximum time step according to the CFL-criterion, |
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| 317 | !-- individually for each velocity component |
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| 318 | dt_u_l = 999999.9 |
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| 319 | dt_v_l = 999999.9 |
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| 320 | dt_w_l = 999999.9 |
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| 321 | DO i = nxl, nxr |
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| 322 | DO j = nys, nyn |
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| 323 | DO k = nzb+1, nzt |
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| 324 | dt_u_l = MIN( dt_u_l, ( dx / ( ABS( u(k,j,i) - u_gtrans ) + 1.0E-10 ) ) ) |
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| 325 | dt_v_l = MIN( dt_v_l, ( dy / ( ABS( v(k,j,i) - v_gtrans ) + 1.0E-10 ) ) ) |
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| 326 | dt_w_l = MIN( dt_w_l, ( dzu(k) / ( ABS( w(k,j,i) ) + 1.0E-10 ) ) ) |
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| 327 | ENDDO |
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| 328 | ENDDO |
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| 329 | ENDDO |
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| 330 | |
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| 331 | #if defined( __parallel ) |
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| 332 | reduce_l(1) = dt_u_l |
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| 333 | reduce_l(2) = dt_v_l |
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| 334 | reduce_l(3) = dt_w_l |
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| 335 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 336 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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| 337 | dt_u = reduce(1) |
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| 338 | dt_v = reduce(2) |
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| 339 | dt_w = reduce(3) |
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| 340 | #else |
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| 341 | dt_u = dt_u_l |
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| 342 | dt_v = dt_v_l |
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| 343 | dt_w = dt_w_l |
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| 344 | #endif |
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| 345 | |
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| 346 | #endif |
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| 347 | |
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| 348 | ! |
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| 349 | !-- Compute time step according to the diffusion criterion. |
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| 350 | !-- First calculate minimum grid spacing which only depends on index k |
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| 351 | !-- Note: also at k=nzb+1 a full grid length is being assumed, although |
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| 352 | !-- in the Prandtl-layer friction term only dz/2 is used. |
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| 353 | !-- Experience from the old model seems to justify this. |
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| 354 | dt_diff_l = 999999.0 |
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| 355 | |
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| 356 | DO k = nzb+1, nzt |
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| 357 | dxyz2_min(k) = MIN( dx2, dy2, dzw(k)*dzw(k) ) * 0.125 |
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| 358 | ENDDO |
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| 359 | |
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| 360 | !$OMP PARALLEL private(i,j,k,value) reduction(MIN: dt_diff_l) |
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| 361 | !$OMP DO |
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| 362 | !$acc parallel loop collapse(3) present( kh, km ) |
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| 363 | DO i = nxl, nxr |
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| 364 | DO j = nys, nyn |
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| 365 | DO k = nzb+1, nzt |
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| 366 | dt_diff_l = MIN( dt_diff_l, dxyz2_min(k) / & |
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| 367 | ( MAX( kh(k,j,i), km(k,j,i) ) + 1E-20 ) ) |
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| 368 | ENDDO |
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| 369 | ENDDO |
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| 370 | ENDDO |
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| 371 | !$acc end parallel |
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| 372 | !$OMP END PARALLEL |
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| 373 | #if defined( __parallel ) |
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| 374 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 375 | CALL MPI_ALLREDUCE( dt_diff_l, dt_diff, 1, MPI_REAL, MPI_MIN, comm2d, & |
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| 376 | ierr ) |
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| 377 | #else |
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| 378 | dt_diff = dt_diff_l |
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| 379 | #endif |
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| 380 | |
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| 381 | ! |
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| 382 | !-- Additional timestep criterion with plant canopies: |
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| 383 | !-- it is not allowed to extract more than the available momentum |
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| 384 | IF ( plant_canopy ) THEN |
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| 385 | |
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| 386 | dt_plant_canopy_l = 0.0 |
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| 387 | DO i = nxl, nxr |
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| 388 | DO j = nys, nyn |
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| 389 | DO k = nzb+1, nzt |
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| 390 | dt_plant_canopy_u = cdc(k,j,i) * lad_u(k,j,i) * & |
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| 391 | SQRT( u(k,j,i)**2 + & |
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| 392 | ( ( v(k,j,i-1) + & |
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| 393 | v(k,j,i) + & |
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| 394 | v(k,j+1,i) + & |
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| 395 | v(k,j+1,i-1) ) & |
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| 396 | / 4.0 )**2 + & |
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| 397 | ( ( w(k-1,j,i-1) + & |
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| 398 | w(k-1,j,i) + & |
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| 399 | w(k,j,i-1) + & |
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| 400 | w(k,j,i) ) & |
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| 401 | / 4.0 )**2 ) |
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| 402 | IF ( dt_plant_canopy_u > dt_plant_canopy_l ) THEN |
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| 403 | dt_plant_canopy_l = dt_plant_canopy_u |
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| 404 | ENDIF |
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| 405 | dt_plant_canopy_v = cdc(k,j,i) * lad_v(k,j,i) * & |
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| 406 | SQRT( ( ( u(k,j-1,i) + & |
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| 407 | u(k,j-1,i+1) + & |
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| 408 | u(k,j,i) + & |
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| 409 | u(k,j,i+1) ) & |
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| 410 | / 4.0 )**2 + & |
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| 411 | v(k,j,i)**2 + & |
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| 412 | ( ( w(k-1,j-1,i) + & |
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| 413 | w(k-1,j,i) + & |
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| 414 | w(k,j-1,i) + & |
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| 415 | w(k,j,i) ) & |
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| 416 | / 4.0 )**2 ) |
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| 417 | IF ( dt_plant_canopy_v > dt_plant_canopy_l ) THEN |
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| 418 | dt_plant_canopy_l = dt_plant_canopy_v |
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| 419 | ENDIF |
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| 420 | dt_plant_canopy_w = cdc(k,j,i) * lad_w(k,j,i) * & |
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| 421 | SQRT( ( ( u(k,j,i) + & |
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| 422 | u(k,j,i+1) + & |
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| 423 | u(k+1,j,i) + & |
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| 424 | u(k+1,j,i+1) ) & |
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| 425 | / 4.0 )**2 + & |
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| 426 | ( ( v(k,j,i) + & |
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| 427 | v(k,j+1,i) + & |
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| 428 | v(k+1,j,i) + & |
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| 429 | v(k+1,j+1,i) ) & |
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| 430 | / 4.0 )**2 + & |
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| 431 | w(k,j,i)**2 ) |
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| 432 | IF ( dt_plant_canopy_w > dt_plant_canopy_l ) THEN |
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| 433 | dt_plant_canopy_l = dt_plant_canopy_w |
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| 434 | ENDIF |
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| 435 | ENDDO |
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| 436 | ENDDO |
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| 437 | ENDDO |
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| 438 | |
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| 439 | IF ( dt_plant_canopy_l > 0.0 ) THEN |
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| 440 | ! |
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| 441 | !-- Invert dt_plant_canopy_l and apply a security timestep factor 0.1 |
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| 442 | dt_plant_canopy_l = 0.1 / dt_plant_canopy_l |
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| 443 | ELSE |
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| 444 | ! |
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| 445 | !-- In case of inhomogeneous plant canopy, some processors may have no |
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| 446 | !-- canopy at all. Then use dt_max as dummy instead. |
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| 447 | dt_plant_canopy_l = dt_max |
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| 448 | ENDIF |
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| 449 | |
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| 450 | ! |
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| 451 | !-- Determine the global minumum |
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| 452 | #if defined( __parallel ) |
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| 453 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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| 454 | CALL MPI_ALLREDUCE( dt_plant_canopy_l, dt_plant_canopy, 1, MPI_REAL, & |
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| 455 | MPI_MIN, comm2d, ierr ) |
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| 456 | #else |
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| 457 | dt_plant_canopy = dt_plant_canopy_l |
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| 458 | #endif |
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| 459 | |
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| 460 | ELSE |
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| 461 | ! |
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| 462 | !-- Use dt_diff as dummy value to avoid extra IF branches further below |
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| 463 | dt_plant_canopy = dt_diff |
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| 464 | |
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| 465 | ENDIF |
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| 466 | |
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| 467 | ! |
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| 468 | !-- The time step is the minimum of the 3-4 components and the diffusion time |
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| 469 | !-- step minus a reduction (cfl_factor) to be on the safe side. |
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| 470 | !-- The time step must not exceed the maximum allowed value. |
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| 471 | dt_3d = cfl_factor * MIN( dt_diff, dt_plant_canopy, dt_u, dt_v, dt_w, & |
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| 472 | dt_precipitation ) |
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| 473 | dt_3d = MIN( dt_3d, dt_max ) |
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| 474 | |
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| 475 | ! |
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| 476 | !-- Remember the restricting time step criterion for later output. |
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| 477 | IF ( MIN( dt_u, dt_v, dt_w ) < MIN( dt_diff, dt_plant_canopy ) ) THEN |
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| 478 | timestep_reason = 'A' |
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| 479 | ELSEIF ( dt_plant_canopy < dt_diff ) THEN |
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| 480 | timestep_reason = 'C' |
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| 481 | ELSE |
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| 482 | timestep_reason = 'D' |
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| 483 | ENDIF |
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| 484 | |
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| 485 | ! |
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| 486 | !-- Set flag if the time step becomes too small. |
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| 487 | IF ( dt_3d < ( 0.00001 * dt_max ) ) THEN |
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| 488 | stop_dt = .TRUE. |
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| 489 | |
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| 490 | WRITE( message_string, * ) 'Time step has reached minimum limit.', & |
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| 491 | '&dt = ', dt_3d, ' s Simulation is terminated.', & |
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| 492 | '&old_dt = ', old_dt, ' s', & |
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| 493 | '&dt_u = ', dt_u, ' s', & |
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| 494 | '&dt_v = ', dt_v, ' s', & |
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| 495 | '&dt_w = ', dt_w, ' s', & |
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| 496 | '&dt_diff = ', dt_diff, ' s', & |
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| 497 | '&dt_plant_canopy = ', dt_plant_canopy, ' s', & |
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| 498 | '&u_max = ', u_max, ' m/s k=', u_max_ijk(1), & |
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| 499 | ' j=', u_max_ijk(2), ' i=', u_max_ijk(3), & |
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| 500 | '&v_max = ', v_max, ' m/s k=', v_max_ijk(1), & |
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| 501 | ' j=', v_max_ijk(2), ' i=', v_max_ijk(3), & |
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| 502 | '&w_max = ', w_max, ' m/s k=', w_max_ijk(1), & |
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| 503 | ' j=', w_max_ijk(2), ' i=', w_max_ijk(3) |
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| 504 | CALL message( 'timestep', 'PA0312', 0, 1, 0, 6, 0 ) |
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| 505 | ! |
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| 506 | !-- In case of coupled runs inform the remote model of the termination |
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| 507 | !-- and its reason, provided the remote model has not already been |
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| 508 | !-- informed of another termination reason (terminate_coupled > 0) before. |
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| 509 | #if defined( __parallel ) |
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| 510 | IF ( coupling_mode /= 'uncoupled' .AND. terminate_coupled == 0 ) THEN |
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| 511 | terminate_coupled = 2 |
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| 512 | IF ( myid == 0 ) THEN |
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| 513 | CALL MPI_SENDRECV( & |
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| 514 | terminate_coupled, 1, MPI_INTEGER, target_id, 0, & |
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| 515 | terminate_coupled_remote, 1, MPI_INTEGER, target_id, 0, & |
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| 516 | comm_inter, status, ierr ) |
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| 517 | ENDIF |
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| 518 | CALL MPI_BCAST( terminate_coupled_remote, 1, MPI_INTEGER, 0, comm2d, ierr) |
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| 519 | ENDIF |
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| 520 | #endif |
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| 521 | ENDIF |
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| 522 | |
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| 523 | ! |
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| 524 | !-- Ensure a smooth value (two significant digits) of the timestep. |
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| 525 | div = 1000.0 |
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| 526 | DO WHILE ( dt_3d < div ) |
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| 527 | div = div / 10.0 |
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| 528 | ENDDO |
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| 529 | dt_3d = NINT( dt_3d * 100.0 / div ) * div / 100.0 |
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| 530 | |
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| 531 | ! |
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| 532 | !-- Adjust the time step |
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| 533 | old_dt = dt_3d |
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| 534 | |
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| 535 | ENDIF |
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| 536 | |
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| 537 | CALL cpu_log( log_point(12), 'calculate_timestep', 'stop' ) |
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| 538 | |
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| 539 | END SUBROUTINE timestep |
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