| 1 | SUBROUTINE timestep |
|---|
| 2 | |
|---|
| 3 | !--------------------------------------------------------------------------------! |
|---|
| 4 | ! This file is part of PALM. |
|---|
| 5 | ! |
|---|
| 6 | ! PALM is free software: you can redistribute it and/or modify it under the terms |
|---|
| 7 | ! of the GNU General Public License as published by the Free Software Foundation, |
|---|
| 8 | ! either version 3 of the License, or (at your option) any later version. |
|---|
| 9 | ! |
|---|
| 10 | ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY |
|---|
| 11 | ! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR |
|---|
| 12 | ! A PARTICULAR PURPOSE. See the GNU General Public License for more details. |
|---|
| 13 | ! |
|---|
| 14 | ! You should have received a copy of the GNU General Public License along with |
|---|
| 15 | ! PALM. If not, see <http://www.gnu.org/licenses/>. |
|---|
| 16 | ! |
|---|
| 17 | ! Copyright 1997-2012 Leibniz University Hannover |
|---|
| 18 | !--------------------------------------------------------------------------------! |
|---|
| 19 | ! |
|---|
| 20 | ! Current revisions: |
|---|
| 21 | ! ------------------ |
|---|
| 22 | ! |
|---|
| 23 | ! |
|---|
| 24 | ! Former revisions: |
|---|
| 25 | ! ----------------- |
|---|
| 26 | ! $Id: timestep.f90 1037 2012-10-22 14:10:22Z raasch $ |
|---|
| 27 | ! |
|---|
| 28 | ! 1036 2012-10-22 13:43:42Z raasch |
|---|
| 29 | ! code put under GPL (PALM 3.9) |
|---|
| 30 | ! |
|---|
| 31 | ! 1001 2012-09-13 14:08:46Z raasch |
|---|
| 32 | ! all actions concerning leapfrog scheme removed |
|---|
| 33 | ! |
|---|
| 34 | ! 978 2012-08-09 08:28:32Z fricke |
|---|
| 35 | ! restriction of the outflow damping layer in the diffusion criterion removed |
|---|
| 36 | ! |
|---|
| 37 | ! 866 2012-03-28 06:44:41Z raasch |
|---|
| 38 | ! bugfix for timestep calculation in case of Galilei transformation, |
|---|
| 39 | ! special treatment in case of mirror velocity boundary condition removed |
|---|
| 40 | ! |
|---|
| 41 | ! 707 2011-03-29 11:39:40Z raasch |
|---|
| 42 | ! bc_lr/ns replaced by bc_lr/ns_cyc |
|---|
| 43 | ! |
|---|
| 44 | ! 667 2010-12-23 12:06:00Z suehring/gryschka |
|---|
| 45 | ! Exchange of terminate_coupled between ocean and atmosphere via PE0 |
|---|
| 46 | ! Minimum grid spacing dxyz2_min(k) is now calculated using dzw instead of dzu |
|---|
| 47 | ! |
|---|
| 48 | ! 622 2010-12-10 08:08:13Z raasch |
|---|
| 49 | ! optional barriers included in order to speed up collective operations |
|---|
| 50 | ! |
|---|
| 51 | ! 343 2009-06-24 12:59:09Z maronga |
|---|
| 52 | ! Additional timestep criterion in case of simulations with plant canopy |
|---|
| 53 | ! Output of messages replaced by message handling routine. |
|---|
| 54 | ! |
|---|
| 55 | ! 222 2009-01-12 16:04:16Z letzel |
|---|
| 56 | ! Implementation of a MPI-1 Coupling: replaced myid with target_id |
|---|
| 57 | ! Bugfix for nonparallel execution |
|---|
| 58 | ! |
|---|
| 59 | ! 108 2007-08-24 15:10:38Z letzel |
|---|
| 60 | ! modifications to terminate coupled runs |
|---|
| 61 | ! |
|---|
| 62 | ! RCS Log replace by Id keyword, revision history cleaned up |
|---|
| 63 | ! |
|---|
| 64 | ! Revision 1.21 2006/02/23 12:59:44 raasch |
|---|
| 65 | ! nt_anz renamed current_timestep_number |
|---|
| 66 | ! |
|---|
| 67 | ! Revision 1.1 1997/08/11 06:26:19 raasch |
|---|
| 68 | ! Initial revision |
|---|
| 69 | ! |
|---|
| 70 | ! |
|---|
| 71 | ! Description: |
|---|
| 72 | ! ------------ |
|---|
| 73 | ! Compute the time step under consideration of the FCL and diffusion criterion. |
|---|
| 74 | !------------------------------------------------------------------------------! |
|---|
| 75 | |
|---|
| 76 | USE arrays_3d |
|---|
| 77 | USE control_parameters |
|---|
| 78 | USE cpulog |
|---|
| 79 | USE grid_variables |
|---|
| 80 | USE indices |
|---|
| 81 | USE interfaces |
|---|
| 82 | USE pegrid |
|---|
| 83 | USE statistics |
|---|
| 84 | |
|---|
| 85 | IMPLICIT NONE |
|---|
| 86 | |
|---|
| 87 | INTEGER :: i, j, k, u_max_cfl_ijk(3), v_max_cfl_ijk(3) |
|---|
| 88 | |
|---|
| 89 | REAL :: div, dt_diff, dt_diff_l, dt_plant_canopy, & |
|---|
| 90 | dt_plant_canopy_l, & |
|---|
| 91 | dt_plant_canopy_u, dt_plant_canopy_v, dt_plant_canopy_w, & |
|---|
| 92 | dt_u, dt_v, dt_w, lad_max, & |
|---|
| 93 | u_gtrans_l, u_max_cfl, vabs_max, value, v_gtrans_l, v_max_cfl |
|---|
| 94 | |
|---|
| 95 | REAL, DIMENSION(2) :: uv_gtrans, uv_gtrans_l |
|---|
| 96 | REAL, DIMENSION(nzb+1:nzt) :: dxyz2_min |
|---|
| 97 | |
|---|
| 98 | |
|---|
| 99 | |
|---|
| 100 | CALL cpu_log( log_point(12), 'calculate_timestep', 'start' ) |
|---|
| 101 | |
|---|
| 102 | ! |
|---|
| 103 | !-- In case of Galilei-transform not using the geostrophic wind as translation |
|---|
| 104 | !-- velocity, compute the volume-averaged horizontal velocity components, which |
|---|
| 105 | !-- will then be subtracted from the horizontal wind for the time step and |
|---|
| 106 | !-- horizontal advection routines. |
|---|
| 107 | IF ( galilei_transformation .AND. .NOT. use_ug_for_galilei_tr ) THEN |
|---|
| 108 | IF ( flow_statistics_called ) THEN |
|---|
| 109 | ! |
|---|
| 110 | !-- Horizontal averages already existent, just need to average them |
|---|
| 111 | !-- vertically. |
|---|
| 112 | u_gtrans = 0.0 |
|---|
| 113 | v_gtrans = 0.0 |
|---|
| 114 | DO k = nzb+1, nzt |
|---|
| 115 | u_gtrans = u_gtrans + hom(k,1,1,0) |
|---|
| 116 | v_gtrans = v_gtrans + hom(k,1,2,0) |
|---|
| 117 | ENDDO |
|---|
| 118 | u_gtrans = u_gtrans / REAL( nzt - nzb ) |
|---|
| 119 | v_gtrans = v_gtrans / REAL( nzt - nzb ) |
|---|
| 120 | ELSE |
|---|
| 121 | ! |
|---|
| 122 | !-- Averaging over the entire model domain. |
|---|
| 123 | uv_gtrans_l = 0.0 |
|---|
| 124 | DO i = nxl, nxr |
|---|
| 125 | DO j = nys, nyn |
|---|
| 126 | DO k = nzb+1, nzt |
|---|
| 127 | uv_gtrans_l(1) = uv_gtrans_l(1) + u(k,j,i) |
|---|
| 128 | uv_gtrans_l(2) = uv_gtrans_l(2) + v(k,j,i) |
|---|
| 129 | ENDDO |
|---|
| 130 | ENDDO |
|---|
| 131 | ENDDO |
|---|
| 132 | uv_gtrans_l = uv_gtrans_l / REAL( (nxr-nxl+1)*(nyn-nys+1)*(nzt-nzb) ) |
|---|
| 133 | #if defined( __parallel ) |
|---|
| 134 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
|---|
| 135 | CALL MPI_ALLREDUCE( uv_gtrans_l, uv_gtrans, 2, MPI_REAL, MPI_SUM, & |
|---|
| 136 | comm2d, ierr ) |
|---|
| 137 | u_gtrans = uv_gtrans(1) / REAL( numprocs ) |
|---|
| 138 | v_gtrans = uv_gtrans(2) / REAL( numprocs ) |
|---|
| 139 | #else |
|---|
| 140 | u_gtrans = uv_gtrans_l(1) |
|---|
| 141 | v_gtrans = uv_gtrans_l(2) |
|---|
| 142 | #endif |
|---|
| 143 | ENDIF |
|---|
| 144 | ENDIF |
|---|
| 145 | |
|---|
| 146 | ! |
|---|
| 147 | !-- Determine the maxima of the velocity components. |
|---|
| 148 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, u, 'abs', 0.0, & |
|---|
| 149 | u_max, u_max_ijk ) |
|---|
| 150 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, v, 'abs', 0.0, & |
|---|
| 151 | v_max, v_max_ijk ) |
|---|
| 152 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, w, 'abs', 0.0, & |
|---|
| 153 | w_max, w_max_ijk ) |
|---|
| 154 | |
|---|
| 155 | ! |
|---|
| 156 | !-- In case of Galilei transformation, the horizontal velocity maxima have |
|---|
| 157 | !-- to be calculated from the transformed horizontal velocities |
|---|
| 158 | IF ( galilei_transformation ) THEN |
|---|
| 159 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, u, 'absoff', & |
|---|
| 160 | u_gtrans, u_max_cfl, u_max_cfl_ijk ) |
|---|
| 161 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, v, 'absoff', & |
|---|
| 162 | v_gtrans, v_max_cfl, v_max_cfl_ijk ) |
|---|
| 163 | ELSE |
|---|
| 164 | u_max_cfl = u_max |
|---|
| 165 | v_max_cfl = v_max |
|---|
| 166 | u_max_cfl_ijk = u_max_ijk |
|---|
| 167 | v_max_cfl_ijk = v_max_ijk |
|---|
| 168 | ENDIF |
|---|
| 169 | |
|---|
| 170 | |
|---|
| 171 | IF ( .NOT. dt_fixed ) THEN |
|---|
| 172 | ! |
|---|
| 173 | !-- Variable time step: |
|---|
| 174 | ! |
|---|
| 175 | !-- For each component, compute the maximum time step according to the |
|---|
| 176 | !-- CFL-criterion. |
|---|
| 177 | dt_u = dx / ( ABS( u_max_cfl ) + 1.0E-10 ) |
|---|
| 178 | dt_v = dy / ( ABS( v_max_cfl ) + 1.0E-10 ) |
|---|
| 179 | dt_w = dzu(MAX( 1, w_max_ijk(1) )) / ( ABS( w_max ) + 1.0E-10 ) |
|---|
| 180 | |
|---|
| 181 | ! |
|---|
| 182 | !-- Compute time step according to the diffusion criterion. |
|---|
| 183 | !-- First calculate minimum grid spacing which only depends on index k |
|---|
| 184 | !-- Note: also at k=nzb+1 a full grid length is being assumed, although |
|---|
| 185 | !-- in the Prandtl-layer friction term only dz/2 is used. |
|---|
| 186 | !-- Experience from the old model seems to justify this. |
|---|
| 187 | dt_diff_l = 999999.0 |
|---|
| 188 | |
|---|
| 189 | DO k = nzb+1, nzt |
|---|
| 190 | dxyz2_min(k) = MIN( dx2, dy2, dzw(k)*dzw(k) ) * 0.125 |
|---|
| 191 | ENDDO |
|---|
| 192 | |
|---|
| 193 | !$OMP PARALLEL private(i,j,k,value) reduction(MIN: dt_diff_l) |
|---|
| 194 | !$OMP DO |
|---|
| 195 | DO i = nxl, nxr |
|---|
| 196 | DO j = nys, nyn |
|---|
| 197 | DO k = nzb+1, nzt |
|---|
| 198 | value = dxyz2_min(k) / ( MAX( kh(k,j,i), km(k,j,i) ) + 1E-20 ) |
|---|
| 199 | |
|---|
| 200 | dt_diff_l = MIN( value, dt_diff_l ) |
|---|
| 201 | ENDDO |
|---|
| 202 | ENDDO |
|---|
| 203 | ENDDO |
|---|
| 204 | !$OMP END PARALLEL |
|---|
| 205 | #if defined( __parallel ) |
|---|
| 206 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
|---|
| 207 | CALL MPI_ALLREDUCE( dt_diff_l, dt_diff, 1, MPI_REAL, MPI_MIN, comm2d, & |
|---|
| 208 | ierr ) |
|---|
| 209 | #else |
|---|
| 210 | dt_diff = dt_diff_l |
|---|
| 211 | #endif |
|---|
| 212 | |
|---|
| 213 | ! |
|---|
| 214 | !-- Additional timestep criterion with plant canopies: |
|---|
| 215 | !-- it is not allowed to extract more than the available momentum |
|---|
| 216 | IF ( plant_canopy ) THEN |
|---|
| 217 | |
|---|
| 218 | dt_plant_canopy_l = 0.0 |
|---|
| 219 | DO i = nxl, nxr |
|---|
| 220 | DO j = nys, nyn |
|---|
| 221 | DO k = nzb+1, nzt |
|---|
| 222 | dt_plant_canopy_u = cdc(k,j,i) * lad_u(k,j,i) * & |
|---|
| 223 | SQRT( u(k,j,i)**2 + & |
|---|
| 224 | ( ( v(k,j,i-1) + & |
|---|
| 225 | v(k,j,i) + & |
|---|
| 226 | v(k,j+1,i) + & |
|---|
| 227 | v(k,j+1,i-1) ) & |
|---|
| 228 | / 4.0 )**2 + & |
|---|
| 229 | ( ( w(k-1,j,i-1) + & |
|---|
| 230 | w(k-1,j,i) + & |
|---|
| 231 | w(k,j,i-1) + & |
|---|
| 232 | w(k,j,i) ) & |
|---|
| 233 | / 4.0 )**2 ) |
|---|
| 234 | IF ( dt_plant_canopy_u > dt_plant_canopy_l ) THEN |
|---|
| 235 | dt_plant_canopy_l = dt_plant_canopy_u |
|---|
| 236 | ENDIF |
|---|
| 237 | dt_plant_canopy_v = cdc(k,j,i) * lad_v(k,j,i) * & |
|---|
| 238 | SQRT( ( ( u(k,j-1,i) + & |
|---|
| 239 | u(k,j-1,i+1) + & |
|---|
| 240 | u(k,j,i) + & |
|---|
| 241 | u(k,j,i+1) ) & |
|---|
| 242 | / 4.0 )**2 + & |
|---|
| 243 | v(k,j,i)**2 + & |
|---|
| 244 | ( ( w(k-1,j-1,i) + & |
|---|
| 245 | w(k-1,j,i) + & |
|---|
| 246 | w(k,j-1,i) + & |
|---|
| 247 | w(k,j,i) ) & |
|---|
| 248 | / 4.0 )**2 ) |
|---|
| 249 | IF ( dt_plant_canopy_v > dt_plant_canopy_l ) THEN |
|---|
| 250 | dt_plant_canopy_l = dt_plant_canopy_v |
|---|
| 251 | ENDIF |
|---|
| 252 | dt_plant_canopy_w = cdc(k,j,i) * lad_w(k,j,i) * & |
|---|
| 253 | SQRT( ( ( u(k,j,i) + & |
|---|
| 254 | u(k,j,i+1) + & |
|---|
| 255 | u(k+1,j,i) + & |
|---|
| 256 | u(k+1,j,i+1) ) & |
|---|
| 257 | / 4.0 )**2 + & |
|---|
| 258 | ( ( v(k,j,i) + & |
|---|
| 259 | v(k,j+1,i) + & |
|---|
| 260 | v(k+1,j,i) + & |
|---|
| 261 | v(k+1,j+1,i) ) & |
|---|
| 262 | / 4.0 )**2 + & |
|---|
| 263 | w(k,j,i)**2 ) |
|---|
| 264 | IF ( dt_plant_canopy_w > dt_plant_canopy_l ) THEN |
|---|
| 265 | dt_plant_canopy_l = dt_plant_canopy_w |
|---|
| 266 | ENDIF |
|---|
| 267 | ENDDO |
|---|
| 268 | ENDDO |
|---|
| 269 | ENDDO |
|---|
| 270 | |
|---|
| 271 | IF ( dt_plant_canopy_l > 0.0 ) THEN |
|---|
| 272 | ! |
|---|
| 273 | !-- Invert dt_plant_canopy_l and apply a security timestep factor 0.1 |
|---|
| 274 | dt_plant_canopy_l = 0.1 / dt_plant_canopy_l |
|---|
| 275 | ELSE |
|---|
| 276 | ! |
|---|
| 277 | !-- In case of inhomogeneous plant canopy, some processors may have no |
|---|
| 278 | !-- canopy at all. Then use dt_max as dummy instead. |
|---|
| 279 | dt_plant_canopy_l = dt_max |
|---|
| 280 | ENDIF |
|---|
| 281 | |
|---|
| 282 | ! |
|---|
| 283 | !-- Determine the global minumum |
|---|
| 284 | #if defined( __parallel ) |
|---|
| 285 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
|---|
| 286 | CALL MPI_ALLREDUCE( dt_plant_canopy_l, dt_plant_canopy, 1, MPI_REAL, & |
|---|
| 287 | MPI_MIN, comm2d, ierr ) |
|---|
| 288 | #else |
|---|
| 289 | dt_plant_canopy = dt_plant_canopy_l |
|---|
| 290 | #endif |
|---|
| 291 | |
|---|
| 292 | ELSE |
|---|
| 293 | ! |
|---|
| 294 | !-- Use dt_diff as dummy value to avoid extra IF branches further below |
|---|
| 295 | dt_plant_canopy = dt_diff |
|---|
| 296 | |
|---|
| 297 | ENDIF |
|---|
| 298 | |
|---|
| 299 | ! |
|---|
| 300 | !-- The time step is the minimum of the 3-4 components and the diffusion time |
|---|
| 301 | !-- step minus a reduction (cfl_factor) to be on the safe side. |
|---|
| 302 | !-- The time step must not exceed the maximum allowed value. |
|---|
| 303 | dt_3d = cfl_factor * MIN( dt_diff, dt_plant_canopy, dt_u, dt_v, dt_w ) |
|---|
| 304 | dt_3d = MIN( dt_3d, dt_max ) |
|---|
| 305 | |
|---|
| 306 | ! |
|---|
| 307 | !-- Remember the restricting time step criterion for later output. |
|---|
| 308 | IF ( MIN( dt_u, dt_v, dt_w ) < MIN( dt_diff, dt_plant_canopy ) ) THEN |
|---|
| 309 | timestep_reason = 'A' |
|---|
| 310 | ELSEIF ( dt_plant_canopy < dt_diff ) THEN |
|---|
| 311 | timestep_reason = 'C' |
|---|
| 312 | ELSE |
|---|
| 313 | timestep_reason = 'D' |
|---|
| 314 | ENDIF |
|---|
| 315 | |
|---|
| 316 | ! |
|---|
| 317 | !-- Set flag if the time step becomes too small. |
|---|
| 318 | IF ( dt_3d < ( 0.00001 * dt_max ) ) THEN |
|---|
| 319 | stop_dt = .TRUE. |
|---|
| 320 | |
|---|
| 321 | WRITE( message_string, * ) 'Time step has reached minimum limit.', & |
|---|
| 322 | '&dt = ', dt_3d, ' s Simulation is terminated.', & |
|---|
| 323 | '&old_dt = ', old_dt, ' s', & |
|---|
| 324 | '&dt_u = ', dt_u, ' s', & |
|---|
| 325 | '&dt_v = ', dt_v, ' s', & |
|---|
| 326 | '&dt_w = ', dt_w, ' s', & |
|---|
| 327 | '&dt_diff = ', dt_diff, ' s', & |
|---|
| 328 | '&dt_plant_canopy = ', dt_plant_canopy, ' s', & |
|---|
| 329 | '&u_max_cfl = ', u_max_cfl, ' m/s k=', u_max_cfl_ijk(1), & |
|---|
| 330 | ' j=', u_max_ijk(2), ' i=', u_max_ijk(3), & |
|---|
| 331 | '&v_max_cfl = ', v_max_cfl, ' m/s k=', v_max_cfl_ijk(1), & |
|---|
| 332 | ' j=', v_max_ijk(2), ' i=', v_max_ijk(3), & |
|---|
| 333 | '&w_max = ', w_max, ' m/s k=', w_max_ijk(1), & |
|---|
| 334 | ' j=', w_max_ijk(2), ' i=', w_max_ijk(3) |
|---|
| 335 | CALL message( 'timestep', 'PA0312', 0, 1, 0, 6, 0 ) |
|---|
| 336 | ! |
|---|
| 337 | !-- In case of coupled runs inform the remote model of the termination |
|---|
| 338 | !-- and its reason, provided the remote model has not already been |
|---|
| 339 | !-- informed of another termination reason (terminate_coupled > 0) before. |
|---|
| 340 | #if defined( __parallel ) |
|---|
| 341 | IF ( coupling_mode /= 'uncoupled' .AND. terminate_coupled == 0 ) THEN |
|---|
| 342 | terminate_coupled = 2 |
|---|
| 343 | IF ( myid == 0 ) THEN |
|---|
| 344 | CALL MPI_SENDRECV( & |
|---|
| 345 | terminate_coupled, 1, MPI_INTEGER, target_id, 0, & |
|---|
| 346 | terminate_coupled_remote, 1, MPI_INTEGER, target_id, 0, & |
|---|
| 347 | comm_inter, status, ierr ) |
|---|
| 348 | ENDIF |
|---|
| 349 | CALL MPI_BCAST( terminate_coupled_remote, 1, MPI_INTEGER, 0, comm2d, ierr) |
|---|
| 350 | ENDIF |
|---|
| 351 | #endif |
|---|
| 352 | ENDIF |
|---|
| 353 | |
|---|
| 354 | ! |
|---|
| 355 | !-- Ensure a smooth value (two significant digits) of the timestep. |
|---|
| 356 | div = 1000.0 |
|---|
| 357 | DO WHILE ( dt_3d < div ) |
|---|
| 358 | div = div / 10.0 |
|---|
| 359 | ENDDO |
|---|
| 360 | dt_3d = NINT( dt_3d * 100.0 / div ) * div / 100.0 |
|---|
| 361 | |
|---|
| 362 | ! |
|---|
| 363 | !-- Adjust the time step |
|---|
| 364 | old_dt = dt_3d |
|---|
| 365 | |
|---|
| 366 | ENDIF |
|---|
| 367 | |
|---|
| 368 | CALL cpu_log( log_point(12), 'calculate_timestep', 'stop' ) |
|---|
| 369 | |
|---|
| 370 | END SUBROUTINE timestep |
|---|
