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source: palm/trunk/SOURCE/timestep.f90 @ 3170

Last change on this file since 3170 was 3120, checked in by gronemeier, 6 years ago
implementation of dynamic sgs model
Property svn:keywords set to `Id`
File size: 16.3 KB

Rev	Line
[1682]	1	!> @file timestep.f90
[2000]	2	!------------------------------------------------------------------------------!
[2696]	3	! This file is part of the PALM model system.
[1036]	4	!
[2000]	5	! PALM is free software: you can redistribute it and/or modify it under the
	6	! terms of the GNU General Public License as published by the Free Software
	7	! Foundation, either version 3 of the License, or (at your option) any later
	8	! version.
[1036]	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	!
[2718]	17	! Copyright 1997-2018 Leibniz Universitaet Hannover
[2000]	18	!------------------------------------------------------------------------------!
[1036]	19	!
[258]	20	! Current revisions:
[866]	21	! ------------------
[1485]	22	!
[3049]	23	!
[1485]	24	! Former revisions:
	25	! -----------------
	26	! $Id: timestep.f90 3120 2018-07-11 18:30:57Z suehring $
[3120]	27	! Put ABS( km ) in computation of time step according to the diffusion criterion
	28	!
	29	! 3084 2018-06-19 15:30:55Z gronemeier
[3084]	30	! limit increase of dt_3d only in case of RANS mode
	31	!
	32	! 3083 2018-06-19 14:03:12Z gronemeier
[3083]	33	! limit dt_3d to be at maximum 2*old_dt; define old_dt at beginning of routine
	34	! Add km/kh_max
	35	!
	36	! 3049 2018-05-29 13:52:36Z Giersch
[3049]	37	! Error messages revised
	38	!
	39	! 3045 2018-05-28 07:55:41Z Giersch
[3045]	40	! Error message revised
	41	!
	42	! 2718 2018-01-02 08:49:38Z maronga
[2716]	43	! Corrected "Former revisions" section
	44	!
	45	! 2696 2017-12-14 17:12:51Z kanani
	46	! Change in file header (GPL part)
	47	!
	48	! 2365 2017-08-21 14:59:59Z kanani
[2365]	49	! Vertical grid nesting: Sync fine and coarse grid timestep (SadiqHuq)
	50	!
	51	! 2258 2017-06-08 07:55:13Z suehring
[2258]	52	! Bugfix, add pre-preprocessor directives to enable non-parrallel mode
[1485]	53	!
[2258]	54	! 2168 2017-03-06 13:08:38Z suehring
	55	!
[2131]	56	! 2130 2017-01-24 16:25:39Z raasch
	57	! bugfix: in case of nested runs the stop condition in case of too small
	58	! timesteps is communicated to all parent/child processes,
	59	! some formatting done
	60	!
[2119]	61	! 2118 2017-01-17 16:38:49Z raasch
	62	! OpenACC directives and related part of code removed
	63	!
[2001]	64	! 2000 2016-08-20 18:09:15Z knoop
	65	! Forced header and separation lines into 80 columns
	66	!
[1851]	67	! 1849 2016-04-08 11:33:18Z hoffmann
	68	! Adapted for modularization of microphysics
[1852]	69	!
[1683]	70	! 1682 2015-10-07 23:56:08Z knoop
	71	! Code annotations made doxygen readable
	72	!
[1485]	73	! 1484 2014-10-21 10:53:05Z kanani
[1484]	74	! Changes due to new module structure of the plant canopy model:
	75	! calculations and parameters related to the plant canopy model removed
	76	! (the limitation of the canopy drag, i.e. that the canopy drag itself should
	77	! not change the sign of the velocity components, is now assured for in the
	78	! calculation of the canopy tendency terms in subroutine plant_canopy_model)
[1343]	79	!
	80	! 1342 2014-03-26 17:04:47Z kanani
	81	! REAL constants defined as wp-kind
	82	!
[1323]	83	! 1322 2014-03-20 16:38:49Z raasch
	84	! REAL functions provided with KIND-attribute
	85	!
[1321]	86	! 1320 2014-03-20 08:40:49Z raasch
[1320]	87	! ONLY-attribute added to USE-statements,
	88	! kind-parameters added to all INTEGER and REAL declaration statements,
	89	! kinds are defined in new module kinds,
	90	! old module precision_kind is removed,
	91	! revision history before 2012 removed,
	92	! comment fields (!:) to be used for variable explanations added to
	93	! all variable declaration statements
[1321]	94	!
[1258]	95	! 1257 2013-11-08 15:18:40Z raasch
	96	! openacc porting
	97	! bugfix for calculation of advective timestep in case of vertically stretched
	98	! grids
	99	!
[1093]	100	! 1092 2013-02-02 11:24:22Z raasch
	101	! unused variables removed
	102	!
[1054]	103	! 1053 2012-11-13 17:11:03Z hoffmann
	104	! timestep is reduced in two-moment cloud scheme according to the maximum
	105	! terminal velocity of rain drops
	106	!
[1037]	107	! 1036 2012-10-22 13:43:42Z raasch
	108	! code put under GPL (PALM 3.9)
	109	!
[1002]	110	! 1001 2012-09-13 14:08:46Z raasch
	111	! all actions concerning leapfrog scheme removed
	112	!
[979]	113	! 978 2012-08-09 08:28:32Z fricke
	114	! restriction of the outflow damping layer in the diffusion criterion removed
	115	!
[867]	116	! 866 2012-03-28 06:44:41Z raasch
	117	! bugfix for timestep calculation in case of Galilei transformation,
	118	! special treatment in case of mirror velocity boundary condition removed
	119	!
[1]	120	! Revision 1.1 1997/08/11 06:26:19 raasch
	121	! Initial revision
	122	!
	123	!
	124	! Description:
	125	! ------------
[1682]	126	!> Compute the time step under consideration of the FCL and diffusion criterion.
[1]	127	!------------------------------------------------------------------------------!
[1682]	128	SUBROUTINE timestep
	129
[1]	130
[1320]	131	USE arrays_3d, &
[1484]	132	ONLY: dzu, dzw, kh, km, u, v, w
[1320]	133
	134	USE control_parameters, &
	135	ONLY: cfl_factor, coupling_mode, dt_3d, dt_fixed, dt_max, &
[3084]	136	galilei_transformation, old_dt, message_string, rans_mode, &
[1320]	137	stop_dt, terminate_coupled, terminate_coupled_remote, &
	138	timestep_reason, u_gtrans, use_ug_for_galilei_tr, v_gtrans
	139
	140	USE cpulog, &
	141	ONLY: cpu_log, log_point
	142
	143	USE grid_variables, &
	144	ONLY: dx, dx2, dy, dy2
	145
	146	USE indices, &
	147	ONLY: nxl, nxlg, nxr, nxrg, nyn, nyng, nys, nysg, nzb, nzt
	148
[1]	149	USE interfaces
[1320]	150
	151	USE kinds
	152
[1849]	153	USE microphysics_mod, &
	154	ONLY: dt_precipitation
	155
[1]	156	USE pegrid
	157
[2130]	158	USE pmc_interface, &
	159	ONLY: nested_run
	160
[1320]	161	USE statistics, &
	162	ONLY: flow_statistics_called, hom, u_max, u_max_ijk, v_max, v_max_ijk,&
	163	w_max, w_max_ijk
	164
[2365]	165	USE vertical_nesting_mod, &
	166	ONLY: vnested, vnest_timestep_sync
	167
[1]	168	IMPLICIT NONE
	169
[1682]	170	INTEGER(iwp) :: i !<
	171	INTEGER(iwp) :: j !<
	172	INTEGER(iwp) :: k !<
[3083]	173	INTEGER(iwp) :: km_max_ijk(3) = -1 !< index values (i,j,k) of location where km_max occurs
	174	INTEGER(iwp) :: kh_max_ijk(3) = -1 !< index values (i,j,k) of location where kh_max occurs
[1]	175
[2130]	176	LOGICAL :: stop_dt_local !< local switch for controlling the time stepping
	177
[1682]	178	REAL(wp) :: div !<
	179	REAL(wp) :: dt_diff !<
	180	REAL(wp) :: dt_diff_l !<
	181	REAL(wp) :: dt_u !<
	182	REAL(wp) :: dt_u_l !<
	183	REAL(wp) :: dt_v !<
	184	REAL(wp) :: dt_v_l !<
	185	REAL(wp) :: dt_w !<
	186	REAL(wp) :: dt_w_l !<
[3083]	187	REAL(wp) :: km_max !< maximum of Km in entire domain
	188	REAL(wp) :: kh_max !< maximum of Kh in entire domain
[1682]	189	REAL(wp) :: u_gtrans_l !<
	190	REAL(wp) :: u_max_l !<
	191	REAL(wp) :: u_min_l !<
	192	REAL(wp) :: value !<
	193	REAL(wp) :: v_gtrans_l !<
	194	REAL(wp) :: v_max_l !<
	195	REAL(wp) :: v_min_l !<
	196	REAL(wp) :: w_max_l !<
	197	REAL(wp) :: w_min_l !<
[1320]	198
[1682]	199	REAL(wp), DIMENSION(2) :: uv_gtrans !<
	200	REAL(wp), DIMENSION(2) :: uv_gtrans_l !<
	201	REAL(wp), DIMENSION(3) :: reduce !<
	202	REAL(wp), DIMENSION(3) :: reduce_l !<
	203	REAL(wp), DIMENSION(nzb+1:nzt) :: dxyz2_min !<
[1]	204
	205
	206	CALL cpu_log( log_point(12), 'calculate_timestep', 'start' )
[3083]	207	!
	208	!-- Save former time step as reference
	209	old_dt = dt_3d
[1]	210
	211	!
	212	!-- In case of Galilei-transform not using the geostrophic wind as translation
	213	!-- velocity, compute the volume-averaged horizontal velocity components, which
	214	!-- will then be subtracted from the horizontal wind for the time step and
	215	!-- horizontal advection routines.
	216	IF ( galilei_transformation .AND. .NOT. use_ug_for_galilei_tr ) THEN
	217	IF ( flow_statistics_called ) THEN
	218	!
	219	!-- Horizontal averages already existent, just need to average them
	220	!-- vertically.
[1342]	221	u_gtrans = 0.0_wp
	222	v_gtrans = 0.0_wp
[1]	223	DO k = nzb+1, nzt
	224	u_gtrans = u_gtrans + hom(k,1,1,0)
	225	v_gtrans = v_gtrans + hom(k,1,2,0)
	226	ENDDO
[1322]	227	u_gtrans = u_gtrans / REAL( nzt - nzb, KIND=wp )
	228	v_gtrans = v_gtrans / REAL( nzt - nzb, KIND=wp )
[1]	229	ELSE
	230	!
	231	!-- Averaging over the entire model domain.
[1342]	232	u_gtrans_l = 0.0_wp
	233	v_gtrans_l = 0.0_wp
[1]	234	DO i = nxl, nxr
	235	DO j = nys, nyn
	236	DO k = nzb+1, nzt
[1257]	237	u_gtrans_l = u_gtrans_l + u(k,j,i)
	238	v_gtrans_l = v_gtrans_l + v(k,j,i)
[1]	239	ENDDO
	240	ENDDO
	241	ENDDO
[2130]	242	uv_gtrans_l(1) = u_gtrans_l / &
	243	REAL( (nxr-nxl+1)(nyn-nys+1)(nzt-nzb), KIND=wp )
	244	uv_gtrans_l(2) = v_gtrans_l / &
	245	REAL( (nxr-nxl+1)(nyn-nys+1)(nzt-nzb), KIND=wp )
[1]	246	#if defined( __parallel )
[622]	247	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
[2130]	248	CALL MPI_ALLREDUCE( uv_gtrans_l, uv_gtrans, 2, MPI_REAL, MPI_SUM, &
[1]	249	comm2d, ierr )
[1322]	250	u_gtrans = uv_gtrans(1) / REAL( numprocs, KIND=wp )
	251	v_gtrans = uv_gtrans(2) / REAL( numprocs, KIND=wp )
[1]	252	#else
	253	u_gtrans = uv_gtrans_l(1)
	254	v_gtrans = uv_gtrans_l(2)
	255	#endif
	256	ENDIF
	257	ENDIF
	258
[866]	259	!
[1257]	260	!-- Determine the maxima of the velocity components, including their
	261	!-- grid index positions.
[1320]	262	CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, u, 'abs', 0.0_wp, &
[866]	263	u_max, u_max_ijk )
[1320]	264	CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, v, 'abs', 0.0_wp, &
[866]	265	v_max, v_max_ijk )
[1320]	266	CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, w, 'abs', 0.0_wp, &
[866]	267	w_max, w_max_ijk )
	268
[1257]	269	IF ( .NOT. dt_fixed ) THEN
[866]	270	!
[1257]	271	!-- Variable time step:
	272	!-- Calculate the maximum time step according to the CFL-criterion,
	273	!-- individually for each velocity component
[1342]	274	dt_u_l = 999999.9_wp
	275	dt_v_l = 999999.9_wp
	276	dt_w_l = 999999.9_wp
[1257]	277	DO i = nxl, nxr
	278	DO j = nys, nyn
	279	DO k = nzb+1, nzt
[2130]	280	dt_u_l = MIN( dt_u_l, ( dx / &
	281	( ABS( u(k,j,i) - u_gtrans ) + 1.0E-10_wp ) ) )
	282	dt_v_l = MIN( dt_v_l, ( dy / &
	283	( ABS( v(k,j,i) - v_gtrans ) + 1.0E-10_wp ) ) )
	284	dt_w_l = MIN( dt_w_l, ( dzu(k) / &
	285	( ABS( w(k,j,i) ) + 1.0E-10_wp ) ) )
[1257]	286	ENDDO
	287	ENDDO
	288	ENDDO
[1]	289
[1257]	290	#if defined( __parallel )
	291	reduce_l(1) = dt_u_l
	292	reduce_l(2) = dt_v_l
	293	reduce_l(3) = dt_w_l
	294	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
	295	CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr )
	296	dt_u = reduce(1)
	297	dt_v = reduce(2)
	298	dt_w = reduce(3)
	299	#else
	300	dt_u = dt_u_l
	301	dt_v = dt_v_l
	302	dt_w = dt_w_l
	303	#endif
	304
[1]	305	!
	306	!-- Compute time step according to the diffusion criterion.
[3120]	307	!-- First calculate minimum grid spacing which only depends on index k.
	308	!-- When using the dynamic subgrid model, negative km are possible.
[1342]	309	dt_diff_l = 999999.0_wp
[1]	310
	311	DO k = nzb+1, nzt
[1342]	312	dxyz2_min(k) = MIN( dx2, dy2, dzw(k)dzw(k) ) 0.125_wp
[1]	313	ENDDO
	314
[2118]	315	!$OMP PARALLEL private(i,j,k,value) reduction(MIN: dt_diff_l)
	316	!$OMP DO
[1]	317	DO i = nxl, nxr
	318	DO j = nys, nyn
	319	DO k = nzb+1, nzt
[2130]	320	dt_diff_l = MIN( dt_diff_l, dxyz2_min(k) / &
[3120]	321	( MAX( kh(k,j,i), ABS( km(k,j,i) ) ) &
	322	+ 1E-20_wp ) )
[1]	323	ENDDO
	324	ENDDO
	325	ENDDO
[2118]	326	!$OMP END PARALLEL
[1]	327	#if defined( __parallel )
[622]	328	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
[2130]	329	CALL MPI_ALLREDUCE( dt_diff_l, dt_diff, 1, MPI_REAL, MPI_MIN, comm2d, &
[1]	330	ierr )
	331	#else
	332	dt_diff = dt_diff_l
	333	#endif
	334
	335	!
[316]	336	!-- The time step is the minimum of the 3-4 components and the diffusion time
[1001]	337	!-- step minus a reduction (cfl_factor) to be on the safe side.
[3084]	338	!-- The time step must not exceed the maximum allowed value.
[2130]	339	dt_3d = cfl_factor * MIN( dt_diff, dt_u, dt_v, dt_w, dt_precipitation )
[3084]	340	dt_3d = MIN( dt_3d, dt_max )
	341	!
	342	!-- In RANS mode, the time step must not increase by more than a factor of 2
	343	IF ( rans_mode ) dt_3d = MIN( dt_3d, dt_max, 2.0_wp * old_dt )
[1]	344
	345	!
	346	!-- Remember the restricting time step criterion for later output.
[1484]	347	IF ( MIN( dt_u, dt_v, dt_w ) < dt_diff ) THEN
[1]	348	timestep_reason = 'A'
	349	ELSE
	350	timestep_reason = 'D'
	351	ENDIF
	352
	353	!
	354	!-- Set flag if the time step becomes too small.
[1342]	355	IF ( dt_3d < ( 0.00001_wp * dt_max ) ) THEN
[1]	356	stop_dt = .TRUE.
[108]	357
[3083]	358	!
	359	!-- Determine the maxima of the diffusion coefficients, including their
	360	!-- grid index positions.
	361	CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, km, 'abs', &
	362	0.0_wp, km_max, km_max_ijk )
	363	CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, kh, 'abs', &
	364	0.0_wp, kh_max, kh_max_ijk )
	365
[2130]	366	WRITE( message_string, * ) 'Time step has reached minimum limit.', &
[3046]	367	'&dt = ', dt_3d, ' s Simulation is terminated.', &
	368	'&old_dt = ', old_dt, ' s', &
	369	'&dt_u = ', dt_u, ' s', &
	370	'&dt_v = ', dt_v, ' s', &
	371	'&dt_w = ', dt_w, ' s', &
	372	'&dt_diff = ', dt_diff, ' s', &
[3083]	373	'&u_max = ', u_max, ' m/s k=', u_max_ijk(1), &
[2130]	374	' j=', u_max_ijk(2), ' i=', u_max_ijk(3), &
[3083]	375	'&v_max = ', v_max, ' m/s k=', v_max_ijk(1), &
[2130]	376	' j=', v_max_ijk(2), ' i=', v_max_ijk(3), &
[3083]	377	'&w_max = ', w_max, ' m/s k=', w_max_ijk(1), &
	378	' j=', w_max_ijk(2), ' i=', w_max_ijk(3), &
	379	'&km_max = ', km_max, ' m2/s2 k=', km_max_ijk(1), &
	380	' j=', km_max_ijk(2), ' i=', km_max_ijk(3), &
	381	'&kh_max = ', kh_max, ' m2/s2 k=', kh_max_ijk(1), &
	382	' j=', kh_max_ijk(2), ' i=', kh_max_ijk(3)
[258]	383	CALL message( 'timestep', 'PA0312', 0, 1, 0, 6, 0 )
[108]	384	!
	385	!-- In case of coupled runs inform the remote model of the termination
	386	!-- and its reason, provided the remote model has not already been
	387	!-- informed of another termination reason (terminate_coupled > 0) before.
[222]	388	#if defined( __parallel )
[108]	389	IF ( coupling_mode /= 'uncoupled' .AND. terminate_coupled == 0 ) THEN
	390	terminate_coupled = 2
[2130]	391	IF ( myid == 0 ) THEN
[667]	392	CALL MPI_SENDRECV( &
[2130]	393	terminate_coupled, 1, MPI_INTEGER, target_id, 0, &
	394	terminate_coupled_remote, 1, MPI_INTEGER, target_id, 0, &
[667]	395	comm_inter, status, ierr )
	396	ENDIF
[2130]	397	CALL MPI_BCAST( terminate_coupled_remote, 1, MPI_INTEGER, 0, &
	398	comm2d, ierr)
[108]	399	ENDIF
[222]	400	#endif
[1]	401	ENDIF
	402
	403	!
[2130]	404	!-- In case of nested runs all parent/child processes have to terminate if
	405	!-- one process has set the stop flag, i.e. they need to set the stop flag
	406	!-- too.
	407	IF ( nested_run ) THEN
	408	stop_dt_local = stop_dt
[2258]	409	#if defined( __parallel )
[2130]	410	CALL MPI_ALLREDUCE( stop_dt_local, stop_dt, 1, MPI_LOGICAL, MPI_LOR, &
	411	MPI_COMM_WORLD, ierr )
[2258]	412	#endif
[2130]	413	ENDIF
	414
	415	!
[1001]	416	!-- Ensure a smooth value (two significant digits) of the timestep.
[1342]	417	div = 1000.0_wp
[1001]	418	DO WHILE ( dt_3d < div )
[1342]	419	div = div / 10.0_wp
[1001]	420	ENDDO
[1342]	421	dt_3d = NINT( dt_3d * 100.0_wp / div ) * div / 100.0_wp
[1]	422
[1001]	423	ENDIF
[1]	424
[2365]	425	!
	426	!-- Vertical nesting: coarse and fine grid timestep has to be identical
	427	IF ( vnested ) CALL vnest_timestep_sync
	428
[1]	429	CALL cpu_log( log_point(12), 'calculate_timestep', 'stop' )
	430
	431	END SUBROUTINE timestep

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