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source: palm/trunk/SOURCE/poismg_noopt.f90 @ 2126

Last change on this file since 2126 was 2101, checked in by suehring, 8 years ago
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1	!> @file poismg_noopt.f90
2	!------------------------------------------------------------------------------!
3	! This file is part of PALM.
4	!
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.
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 1997-2017 Leibniz Universitaet Hannover
18	!------------------------------------------------------------------------------!
19	!
20	! Current revisions:
21	! -----------------
22	!
23	!
24	! Former revisions:
25	! -----------------
26	! $Id: poismg_noopt.f90 2101 2017-01-05 16:42:31Z raasch $
27	!
28	! 2037 2016-10-26 11:15:40Z knoop
29	! Anelastic approximation implemented
30	!
31	! 2021 2016-10-07 14:08:57Z suehring
32	! Bugfix: restore nest_bound_(l/r/s/n) in case of mg_switch_to_pe0
33	!
34	! 2000 2016-08-20 18:09:15Z knoop
35	! Forced header and separation lines into 80 columns
36	!
37	! 1934 2016-06-13 09:46:57Z hellstea
38	! Rename subroutines and cpu-measure log points to indicate _noopt version
39	!
40	! 1762 2016-02-25 12:31:13Z hellstea
41	! Introduction of nested domain feature
42	!
43	! 1682 2015-10-07 23:56:08Z knoop
44	! Code annotations made doxygen readable
45	!
46	! 1353 2014-04-08 15:21:23Z heinze
47	! REAL constants provided with KIND-attribute
48	!
49	! 1322 2014-03-20 16:38:49Z raasch
50	! REAL constants defined as wp-kind
51	!
52	! 1320 2014-03-20 08:40:49Z raasch
53	! ONLY-attribute added to USE-statements,
54	! kind-parameters added to all INTEGER and REAL declaration statements,
55	! kinds are defined in new module kinds,
56	! old module precision_kind is removed,
57	! revision history before 2012 removed,
58	! comment fields (!:) to be used for variable explanations added to
59	! all variable declaration statements
60	!
61	! 1318 2014-03-17 13:35:16Z raasch
62	! module interfaces removed
63	!
64	! 1159 2013-05-21 11:58:22Z fricke
65	! bc_lr/ns_dirneu/neudir removed
66	!
67	! 1092 2013-02-02 11:24:22Z raasch
68	! unused variables removed
69	!
70	! 1056 2012-11-16 15:28:04Z raasch
71	! Bugfix: all ghost points have to be used for allocating p3
72	! arrays p2, f2, and f2_l changed from allocatable to automatic
73	!
74	! 1036 2012-10-22 13:43:42Z raasch
75	! code put under GPL (PALM 3.9)
76	!
77	! 996 2012-09-07 10:41:47Z raasch
78	! little reformatting
79	!
80	! 978 2012-08-09 08:28:32Z fricke
81	! bc_lr/ns_dirneu/neudir added
82	!
83	! 880 2012-04-13 06:28:59Z raasch
84	! Bugfix: preprocessor statements for parallel execution added
85	!
86	! 778 2011-11-07 14:18:25Z fricke
87	! Allocation of p3 changes when multigrid is used and the collected field on PE0
88	! has more grid points than the subdomain of an PE.
89	!
90	! 707 2011-03-29 11:39:40Z raasch
91	! p_loc is used instead of p in the main routine (poismg).
92	! On coarse grid levels, gathered data are identically processed on all PEs
93	! (before, on PE0 only), so that the subsequent scattering of data is not
94	! neccessary any more.
95	! bc_lr/ns replaced by bc_lr/ns_cyc/dirrad/raddir
96	! Bugfix: bottom (nzb) and top (nzt+1) boundary conditions set in routines
97	! resid and restrict. They were missed before which may have led to
98	! unpredictable results.
99	!
100	! 667 2010-12-23 12:06:00Z suehring/gryschka
101	! Calls of exchange_horiz are modified.
102	!
103	! 622 2010-12-10 08:08:13Z raasch
104	! optional barriers included in order to speed up collective operations
105	!
106	! 257 2009-03-11 15:17:42Z heinze
107	! Output of messages replaced by message handling routine.
108	!
109	! 181 2008-07-30 07:07:47Z raasch
110	! Bugfix: grid_level+1 has to be used in restrict for flags-array
111	!
112	! 114 2007-10-10 00:03:15Z raasch
113	! Boundary conditions at walls are implicitly set using flag arrays. Only
114	! Neumann BC is allowed. Upper walls are still not realized.
115	! Bottom and top BCs for array f_mg in restrict removed because boundary
116	! values are not needed (right hand side of SOR iteration).
117	!
118	! 75 2007-03-22 09:54:05Z raasch
119	! 2nd+3rd argument removed from exchange horiz
120	!
121	! RCS Log replace by Id keyword, revision history cleaned up
122	!
123	! Revision 1.6 2005/03/26 20:55:54 raasch
124	! Implementation of non-cyclic (Neumann) horizontal boundary conditions,
125	! routine prolong simplified (one call of exchange_horiz spared)
126	!
127	! Revision 1.1 2001/07/20 13:10:51 raasch
128	! Initial revision
129	!
130	!
131	! Description:
132	! ------------
133	!> Solves the Poisson equation for the perturbation pressure with a multigrid
134	!> V- or W-Cycle scheme.
135	!>
136	!> This multigrid method was originally developed for PALM by Joerg Uhlenbrock,
137	!> September 2000 - July 2001.
138	!>
139	!> @attention Loop unrolling and cache optimization in SOR-Red/Black method
140	!> still does not give the expected speedup!
141	!>
142	!> @todo Further work required.
143	!------------------------------------------------------------------------------!
144	SUBROUTINE poismg_noopt( r )
145
146
147	USE arrays_3d, &
148	ONLY: d, p_loc
149
150	USE control_parameters, &
151	ONLY: gathered_size, grid_level, grid_level_count, &
152	maximum_grid_level, message_string, mgcycles, mg_cycles, &
153	mg_switch_to_pe0_level, residual_limit, subdomain_size
154
155	USE cpulog, &
156	ONLY: cpu_log, log_point_s
157
158	USE indices, &
159	ONLY: nxl, nxlg, nxl_mg, nxr, nxrg, nxr_mg, nys, nysg, nys_mg, nyn, &
160	nyng, nyn_mg, nzb, nzt, nzt_mg
161
162	USE kinds
163
164	USE pegrid
165
166	IMPLICIT NONE
167
168	REAL(wp) :: maxerror !<
169	REAL(wp) :: maximum_mgcycles !<
170	REAL(wp) :: residual_norm !<
171
172	REAL(wp), DIMENSION(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) :: r !<
173
174	REAL(wp), DIMENSION(:,:,:), ALLOCATABLE :: p3 !<
175
176
177	CALL cpu_log( log_point_s(29), 'poismg_noopt', 'start' )
178	!
179	!-- Initialize arrays and variables used in this subroutine
180
181	!-- If the number of grid points of the gathered grid, which is collected
182	!-- on PE0, is larger than the number of grid points of an PE, than array
183	!-- p3 will be enlarged.
184	IF ( gathered_size > subdomain_size ) THEN
185	ALLOCATE( p3(nzb:nzt_mg(mg_switch_to_pe0_level)+1,nys_mg( &
186	mg_switch_to_pe0_level)-1:nyn_mg(mg_switch_to_pe0_level)+1,&
187	nxl_mg(mg_switch_to_pe0_level)-1:nxr_mg( &
188	mg_switch_to_pe0_level)+1) )
189	ELSE
190	ALLOCATE ( p3(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
191	ENDIF
192
193	p3 = 0.0_wp
194
195	!
196	!-- Ghost boundaries have to be added to divergence array.
197	!-- Exchange routine needs to know the grid level!
198	grid_level = maximum_grid_level
199	CALL exchange_horiz( d, 1)
200	d(nzb,:,:) = d(nzb+1,:,:)
201
202	!
203	!-- Initiation of the multigrid scheme. Does n cycles until the
204	!-- residual is smaller than the given limit. The accuracy of the solution
205	!-- of the poisson equation will increase with the number of cycles.
206	!-- If the number of cycles is preset by the user, this number will be
207	!-- carried out regardless of the accuracy.
208	grid_level_count = 0
209	mgcycles = 0
210	IF ( mg_cycles == -1 ) THEN
211	maximum_mgcycles = 0
212	residual_norm = 1.0_wp
213	ELSE
214	maximum_mgcycles = mg_cycles
215	residual_norm = 0.0_wp
216	ENDIF
217
218	DO WHILE ( residual_norm > residual_limit .OR. &
219	mgcycles < maximum_mgcycles )
220
221	CALL next_mg_level_noopt( d, p_loc, p3, r)
222
223	!
224	!-- Calculate the residual if the user has not preset the number of
225	!-- cycles to be performed
226	IF ( maximum_mgcycles == 0 ) THEN
227	CALL resid_noopt( d, p_loc, r )
228	maxerror = SUM( r(nzb+1:nzt,nys:nyn,nxl:nxr)**2 )
229
230	#if defined( __parallel )
231	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
232	CALL MPI_ALLREDUCE( maxerror, residual_norm, 1, MPI_REAL, MPI_SUM, &
233	comm2d, ierr)
234	#else
235	residual_norm = maxerror
236	#endif
237	residual_norm = SQRT( residual_norm )
238	ENDIF
239
240	mgcycles = mgcycles + 1
241
242	!
243	!-- If the user has not limited the number of cycles, stop the run in case
244	!-- of insufficient convergence
245	IF ( mgcycles > 1000 .AND. mg_cycles == -1 ) THEN
246	message_string = 'no sufficient convergence within 1000 cycles'
247	CALL message( 'poismg_noopt', 'PA0283', 1, 2, 0, 6, 0 )
248	ENDIF
249
250	ENDDO
251
252	DEALLOCATE( p3 )
253
254	!
255	!-- Unset the grid level. Variable is used to determine the MPI datatypes for
256	!-- ghost point exchange
257	grid_level = 0
258
259	CALL cpu_log( log_point_s(29), 'poismg_noopt', 'stop' )
260
261	END SUBROUTINE poismg_noopt
262
263
264	!------------------------------------------------------------------------------!
265	! Description:
266	! ------------
267	!> Computes the residual of the perturbation pressure.
268	!------------------------------------------------------------------------------!
269	SUBROUTINE resid_noopt( f_mg, p_mg, r )
270
271
272	USE arrays_3d, &
273	ONLY: f1_mg, f2_mg, f3_mg, rho_air_mg
274
275	USE control_parameters, &
276	ONLY: bc_lr_cyc, bc_ns_cyc, grid_level, ibc_p_b, ibc_p_t, inflow_l, &
277	inflow_n, inflow_r, inflow_s, nest_bound_l, nest_bound_n, &
278	nest_bound_r, nest_bound_s, outflow_l, outflow_n, outflow_r, &
279	outflow_s
280
281	USE grid_variables, &
282	ONLY: ddx2_mg, ddy2_mg
283
284	USE indices, &
285	ONLY: flags, wall_flags_1, wall_flags_2, wall_flags_3, wall_flags_4, &
286	wall_flags_5, wall_flags_6, wall_flags_7, wall_flags_8, &
287	wall_flags_9, wall_flags_10, nxl_mg, nxr_mg, nys_mg, nyn_mg, &
288	nzb, nzt_mg
289
290	USE kinds
291
292	IMPLICIT NONE
293
294	INTEGER(iwp) :: i
295	INTEGER(iwp) :: j
296	INTEGER(iwp) :: k
297	INTEGER(iwp) :: l
298
299	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
300	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
301	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f_mg !<
302	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
303	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
304	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: p_mg !<
305	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
306	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
307	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: r !<
308
309	!
310	!-- Calculate the residual
311	l = grid_level
312
313	!
314	!-- Choose flag array of this level
315	SELECT CASE ( l )
316	CASE ( 1 )
317	flags => wall_flags_1
318	CASE ( 2 )
319	flags => wall_flags_2
320	CASE ( 3 )
321	flags => wall_flags_3
322	CASE ( 4 )
323	flags => wall_flags_4
324	CASE ( 5 )
325	flags => wall_flags_5
326	CASE ( 6 )
327	flags => wall_flags_6
328	CASE ( 7 )
329	flags => wall_flags_7
330	CASE ( 8 )
331	flags => wall_flags_8
332	CASE ( 9 )
333	flags => wall_flags_9
334	CASE ( 10 )
335	flags => wall_flags_10
336	END SELECT
337
338	!$OMP PARALLEL PRIVATE (i,j,k)
339	!$OMP DO
340	DO i = nxl_mg(l), nxr_mg(l)
341	DO j = nys_mg(l), nyn_mg(l)
342	DO k = nzb+1, nzt_mg(l)
343	r(k,j,i) = f_mg(k,j,i) &
344	- rho_air_mg(k,l) * ddx2_mg(l) * &
345	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
346	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
347	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
348	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
349	- rho_air_mg(k,l) * ddy2_mg(l) * &
350	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
351	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
352	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
353	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
354	- f2_mg(k,l) * p_mg(k+1,j,i) &
355	- f3_mg(k,l) * &
356	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
357	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
358	+ f1_mg(k,l) * p_mg(k,j,i)
359	!
360	!-- Residual within topography should be zero
361	r(k,j,i) = r(k,j,i) * ( 1.0_wp - IBITS( flags(k,j,i), 6, 1 ) )
362	ENDDO
363	ENDDO
364	ENDDO
365	!$OMP END PARALLEL
366
367	!
368	!-- Horizontal boundary conditions
369	CALL exchange_horiz( r, 1)
370
371	IF ( .NOT. bc_lr_cyc ) THEN
372	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
373	r(:,:,nxl_mg(l)-1) = r(:,:,nxl_mg(l))
374	ENDIF
375	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
376	r(:,:,nxr_mg(l)+1) = r(:,:,nxr_mg(l))
377	ENDIF
378	ENDIF
379
380	IF ( .NOT. bc_ns_cyc ) THEN
381	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
382	r(:,nyn_mg(l)+1,:) = r(:,nyn_mg(l),:)
383	ENDIF
384	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
385	r(:,nys_mg(l)-1,:) = r(:,nys_mg(l),:)
386	ENDIF
387	ENDIF
388
389	!
390	!-- Boundary conditions at bottom and top of the domain.
391	!-- These points are not handled by the above loop. Points may be within
392	!-- buildings, but that doesn't matter.
393	IF ( ibc_p_b == 1 ) THEN
394	r(nzb,:,: ) = r(nzb+1,:,:)
395	ELSE
396	r(nzb,:,: ) = 0.0_wp
397	ENDIF
398
399	IF ( ibc_p_t == 1 ) THEN
400	r(nzt_mg(l)+1,:,: ) = r(nzt_mg(l),:,:)
401	ELSE
402	r(nzt_mg(l)+1,:,: ) = 0.0_wp
403	ENDIF
404
405
406	END SUBROUTINE resid_noopt
407
408
409	!------------------------------------------------------------------------------!
410	! Description:
411	! ------------
412	!> Interpolates the residual on the next coarser grid with "full weighting"
413	!> scheme.
414	!------------------------------------------------------------------------------!
415	SUBROUTINE restrict_noopt( f_mg, r )
416
417
418	USE control_parameters, &
419	ONLY: bc_lr_cyc, bc_ns_cyc, grid_level, ibc_p_b, ibc_p_t, inflow_l, &
420	inflow_n, inflow_r, inflow_s, nest_bound_l, nest_bound_n, &
421	nest_bound_r, nest_bound_s, outflow_l, outflow_n, outflow_r, &
422	outflow_s
423
424	USE indices, &
425	ONLY: flags, wall_flags_1, wall_flags_2, wall_flags_3, wall_flags_4, &
426	wall_flags_5, wall_flags_6, wall_flags_7, wall_flags_8, &
427	wall_flags_9, wall_flags_10, nxl_mg, nxr_mg, nys_mg, nyn_mg, &
428	nzb, nzt_mg
429
430	USE kinds
431
432	IMPLICIT NONE
433
434	INTEGER(iwp) :: i !<
435	INTEGER(iwp) :: ic !<
436	INTEGER(iwp) :: j !<
437	INTEGER(iwp) :: jc !<
438	INTEGER(iwp) :: k !<
439	INTEGER(iwp) :: kc !<
440	INTEGER(iwp) :: l !<
441
442	REAL(wp) :: rkjim !<
443	REAL(wp) :: rkjip !<
444	REAL(wp) :: rkjmi !<
445	REAL(wp) :: rkjmim !<
446	REAL(wp) :: rkjmip !<
447	REAL(wp) :: rkjpi !<
448	REAL(wp) :: rkjpim !<
449	REAL(wp) :: rkjpip !<
450	REAL(wp) :: rkmji !<
451	REAL(wp) :: rkmjim !<
452	REAL(wp) :: rkmjip !<
453	REAL(wp) :: rkmjmi !<
454	REAL(wp) :: rkmjmim !<
455	REAL(wp) :: rkmjmip !<
456	REAL(wp) :: rkmjpi !<
457	REAL(wp) :: rkmjpim !<
458	REAL(wp) :: rkmjpip !<
459
460	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
461	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
462	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f_mg !<
463
464	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level+1)+1, &
465	nys_mg(grid_level+1)-1:nyn_mg(grid_level+1)+1, &
466	nxl_mg(grid_level+1)-1:nxr_mg(grid_level+1)+1) :: r !<
467
468	!
469	!-- Interpolate the residual
470	l = grid_level
471
472	!
473	!-- Choose flag array of the upper level
474	SELECT CASE ( l+1 )
475	CASE ( 1 )
476	flags => wall_flags_1
477	CASE ( 2 )
478	flags => wall_flags_2
479	CASE ( 3 )
480	flags => wall_flags_3
481	CASE ( 4 )
482	flags => wall_flags_4
483	CASE ( 5 )
484	flags => wall_flags_5
485	CASE ( 6 )
486	flags => wall_flags_6
487	CASE ( 7 )
488	flags => wall_flags_7
489	CASE ( 8 )
490	flags => wall_flags_8
491	CASE ( 9 )
492	flags => wall_flags_9
493	CASE ( 10 )
494	flags => wall_flags_10
495	END SELECT
496
497	!$OMP PARALLEL PRIVATE (i,j,k,ic,jc,kc)
498	!$OMP DO
499	DO ic = nxl_mg(l), nxr_mg(l)
500	i = 2*ic
501	DO jc = nys_mg(l), nyn_mg(l)
502	j = 2*jc
503	DO kc = nzb+1, nzt_mg(l)
504	k = 2*kc-1
505	!
506	!-- Use implicit Neumann BCs if the respective gridpoint is inside
507	!-- the building
508	rkjim = r(k,j,i-1) + IBITS( flags(k,j,i-1), 6, 1 ) * &
509	( r(k,j,i) - r(k,j,i-1) )
510	rkjip = r(k,j,i+1) + IBITS( flags(k,j,i+1), 6, 1 ) * &
511	( r(k,j,i) - r(k,j,i+1) )
512	rkjpi = r(k,j+1,i) + IBITS( flags(k,j+1,i), 6, 1 ) * &
513	( r(k,j,i) - r(k,j+1,i) )
514	rkjmi = r(k,j-1,i) + IBITS( flags(k,j-1,i), 6, 1 ) * &
515	( r(k,j,i) - r(k,j-1,i) )
516	rkjmim = r(k,j-1,i-1) + IBITS( flags(k,j-1,i-1), 6, 1 ) * &
517	( r(k,j,i) - r(k,j-1,i-1) )
518	rkjpim = r(k,j+1,i-1) + IBITS( flags(k,j+1,i-1), 6, 1 ) * &
519	( r(k,j,i) - r(k,j+1,i-1) )
520	rkjmip = r(k,j-1,i+1) + IBITS( flags(k,j-1,i+1), 6, 1 ) * &
521	( r(k,j,i) - r(k,j-1,i+1) )
522	rkjpip = r(k,j+1,i+1) + IBITS( flags(k,j+1,i+1), 6, 1 ) * &
523	( r(k,j,i) - r(k,j+1,i+1) )
524	rkmji = r(k-1,j,i) + IBITS( flags(k-1,j,i), 6, 1 ) * &
525	( r(k,j,i) - r(k-1,j,i) )
526	rkmjim = r(k-1,j,i-1) + IBITS( flags(k-1,j,i-1), 6, 1 ) * &
527	( r(k,j,i) - r(k-1,j,i-1) )
528	rkmjip = r(k-1,j,i+1) + IBITS( flags(k-1,j,i+1), 6, 1 ) * &
529	( r(k,j,i) - r(k-1,j,i+1) )
530	rkmjpi = r(k-1,j+1,i) + IBITS( flags(k-1,j+1,i), 6, 1 ) * &
531	( r(k,j,i) - r(k-1,j+1,i) )
532	rkmjmi = r(k-1,j-1,i) + IBITS( flags(k-1,j-1,i), 6, 1 ) * &
533	( r(k,j,i) - r(k-1,j-1,i) )
534	rkmjmim = r(k-1,j-1,i-1) + IBITS( flags(k-1,j-1,i-1), 6, 1 ) * &
535	( r(k,j,i) - r(k-1,j-1,i-1) )
536	rkmjpim = r(k-1,j+1,i-1) + IBITS( flags(k-1,j+1,i-1), 6, 1 ) * &
537	( r(k,j,i) - r(k-1,j+1,i-1) )
538	rkmjmip = r(k-1,j-1,i+1) + IBITS( flags(k-1,j-1,i+1), 6, 1 ) * &
539	( r(k,j,i) - r(k-1,j-1,i+1) )
540	rkmjpip = r(k-1,j+1,i+1) + IBITS( flags(k-1,j+1,i+1), 6, 1 ) * &
541	( r(k,j,i) - r(k-1,j+1,i+1) )
542
543	f_mg(kc,jc,ic) = 1.0_wp / 64.0_wp * ( &
544	8.0_wp * r(k,j,i) &
545	+ 4.0_wp * ( rkjim + rkjip + &
546	rkjpi + rkjmi ) &
547	+ 2.0_wp * ( rkjmim + rkjpim + &
548	rkjmip + rkjpip ) &
549	+ 4.0_wp * rkmji &
550	+ 2.0_wp * ( rkmjim + rkmjim + &
551	rkmjpi + rkmjmi ) &
552	+ ( rkmjmim + rkmjpim + &
553	rkmjmip + rkmjpip ) &
554	+ 4.0_wp * r(k+1,j,i) &
555	+ 2.0_wp * ( r(k+1,j,i-1) + r(k+1,j,i+1) + &
556	r(k+1,j+1,i) + r(k+1,j-1,i) ) &
557	+ ( r(k+1,j-1,i-1) + r(k+1,j+1,i-1) + &
558	r(k+1,j-1,i+1) + r(k+1,j+1,i+1) ) &
559	)
560
561	! f_mg(kc,jc,ic) = 1.0_wp / 64.0_wp * ( &
562	! 8.0_wp * r(k,j,i) &
563	! + 4.0_wp * ( r(k,j,i-1) + r(k,j,i+1) + &
564	! r(k,j+1,i) + r(k,j-1,i) ) &
565	! + 2.0_wp * ( r(k,j-1,i-1) + r(k,j+1,i-1) + &
566	! r(k,j-1,i+1) + r(k,j+1,i+1) ) &
567	! + 4.0_wp * r(k-1,j,i) &
568	! + 2.0_wp * ( r(k-1,j,i-1) + r(k-1,j,i+1) + &
569	! r(k-1,j+1,i) + r(k-1,j-1,i) ) &
570	! + ( r(k-1,j-1,i-1) + r(k-1,j+1,i-1) + &
571	! r(k-1,j-1,i+1) + r(k-1,j+1,i+1) ) &
572	! + 4.0_wp * r(k+1,j,i) &
573	! + 2.0_wp * ( r(k+1,j,i-1) + r(k+1,j,i+1) + &
574	! r(k+1,j+1,i) + r(k+1,j-1,i) ) &
575	! + ( r(k+1,j-1,i-1) + r(k+1,j+1,i-1) + &
576	! r(k+1,j-1,i+1) + r(k+1,j+1,i+1) ) &
577	! )
578	ENDDO
579	ENDDO
580	ENDDO
581	!$OMP END PARALLEL
582
583	!
584	!-- Horizontal boundary conditions
585	CALL exchange_horiz( f_mg, 1)
586
587	IF ( .NOT. bc_lr_cyc ) THEN
588	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
589	f_mg(:,:,nxl_mg(l)-1) = f_mg(:,:,nxl_mg(l))
590	ENDIF
591	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
592	f_mg(:,:,nxr_mg(l)+1) = f_mg(:,:,nxr_mg(l))
593	ENDIF
594	ENDIF
595
596	IF ( .NOT. bc_ns_cyc ) THEN
597	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
598	f_mg(:,nyn_mg(l)+1,:) = f_mg(:,nyn_mg(l),:)
599	ENDIF
600	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
601	f_mg(:,nys_mg(l)-1,:) = f_mg(:,nys_mg(l),:)
602	ENDIF
603	ENDIF
604
605	!
606	!-- Boundary conditions at bottom and top of the domain.
607	!-- These points are not handled by the above loop. Points may be within
608	!-- buildings, but that doesn't matter.
609	IF ( ibc_p_b == 1 ) THEN
610	f_mg(nzb,:,: ) = f_mg(nzb+1,:,:)
611	ELSE
612	f_mg(nzb,:,: ) = 0.0_wp
613	ENDIF
614
615	IF ( ibc_p_t == 1 ) THEN
616	f_mg(nzt_mg(l)+1,:,: ) = f_mg(nzt_mg(l),:,:)
617	ELSE
618	f_mg(nzt_mg(l)+1,:,: ) = 0.0_wp
619	ENDIF
620
621
622	END SUBROUTINE restrict_noopt
623
624
625	!------------------------------------------------------------------------------!
626	! Description:
627	! ------------
628	!> Interpolates the correction of the perturbation pressure
629	!> to the next finer grid.
630	!------------------------------------------------------------------------------!
631	SUBROUTINE prolong_noopt( p, temp )
632
633
634	USE control_parameters, &
635	ONLY: bc_lr_cyc, bc_ns_cyc, grid_level, ibc_p_b, ibc_p_t, inflow_l, &
636	inflow_n, inflow_r, inflow_s, nest_bound_l, nest_bound_n, &
637	nest_bound_r, nest_bound_s, outflow_l, outflow_n, outflow_r, &
638	outflow_s
639
640	USE indices, &
641	ONLY: nxl_mg, nxr_mg, nys_mg, nyn_mg, nzb, nzt_mg
642
643	USE kinds
644
645	IMPLICIT NONE
646
647	INTEGER(iwp) :: i !<
648	INTEGER(iwp) :: j !<
649	INTEGER(iwp) :: k !<
650	INTEGER(iwp) :: l !<
651
652	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level-1)+1, &
653	nys_mg(grid_level-1)-1:nyn_mg(grid_level-1)+1, &
654	nxl_mg(grid_level-1)-1:nxr_mg(grid_level-1)+1 ) :: p !<
655
656	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
657	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
658	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: temp !<
659
660
661	!
662	!-- First, store elements of the coarser grid on the next finer grid
663	l = grid_level
664
665	!$OMP PARALLEL PRIVATE (i,j,k)
666	!$OMP DO
667	DO i = nxl_mg(l-1), nxr_mg(l-1)
668	DO j = nys_mg(l-1), nyn_mg(l-1)
669	!CDIR NODEP
670	DO k = nzb+1, nzt_mg(l-1)
671	!
672	!-- Points of the coarse grid are directly stored on the next finer
673	!-- grid
674	temp(2k-1,2j,2*i) = p(k,j,i)
675	!
676	!-- Points between two coarse-grid points
677	temp(2k-1,2j,2i+1) = 0.5_wp ( p(k,j,i) + p(k,j,i+1) )
678	temp(2k-1,2j+1,2i) = 0.5_wp ( p(k,j,i) + p(k,j+1,i) )
679	temp(2k,2j,2i) = 0.5_wp ( p(k,j,i) + p(k+1,j,i) )
680	!
681	!-- Points in the center of the planes stretched by four points
682	!-- of the coarse grid cube
683	temp(2k-1,2j+1,2i+1) = 0.25_wp ( p(k,j,i) + p(k,j,i+1) + &
684	p(k,j+1,i) + p(k,j+1,i+1) )
685	temp(2k,2j,2i+1) = 0.25_wp ( p(k,j,i) + p(k,j,i+1) + &
686	p(k+1,j,i) + p(k+1,j,i+1) )
687	temp(2k,2j+1,2i) = 0.25_wp ( p(k,j,i) + p(k,j+1,i) + &
688	p(k+1,j,i) + p(k+1,j+1,i) )
689	!
690	!-- Points in the middle of coarse grid cube
691	temp(2k,2j+1,2i+1) = 0.125_wp ( p(k,j,i) + p(k,j,i+1) + &
692	p(k,j+1,i) + p(k,j+1,i+1) + &
693	p(k+1,j,i) + p(k+1,j,i+1) + &
694	p(k+1,j+1,i) + p(k+1,j+1,i+1) )
695	ENDDO
696	ENDDO
697	ENDDO
698	!$OMP END PARALLEL
699
700	!
701	!-- Horizontal boundary conditions
702	CALL exchange_horiz( temp, 1)
703
704	IF ( .NOT. bc_lr_cyc ) THEN
705	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
706	temp(:,:,nxl_mg(l)-1) = temp(:,:,nxl_mg(l))
707	ENDIF
708	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
709	temp(:,:,nxr_mg(l)+1) = temp(:,:,nxr_mg(l))
710	ENDIF
711	ENDIF
712
713	IF ( .NOT. bc_ns_cyc ) THEN
714	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
715	temp(:,nyn_mg(l)+1,:) = temp(:,nyn_mg(l),:)
716	ENDIF
717	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
718	temp(:,nys_mg(l)-1,:) = temp(:,nys_mg(l),:)
719	ENDIF
720	ENDIF
721
722	!
723	!-- Bottom and top boundary conditions
724	IF ( ibc_p_b == 1 ) THEN
725	temp(nzb,:,: ) = temp(nzb+1,:,:)
726	ELSE
727	temp(nzb,:,: ) = 0.0_wp
728	ENDIF
729
730	IF ( ibc_p_t == 1 ) THEN
731	temp(nzt_mg(l)+1,:,: ) = temp(nzt_mg(l),:,:)
732	ELSE
733	temp(nzt_mg(l)+1,:,: ) = 0.0_wp
734	ENDIF
735
736
737	END SUBROUTINE prolong_noopt
738
739
740	!------------------------------------------------------------------------------!
741	! Description:
742	! ------------
743	!> Relaxation method for the multigrid scheme. A Gauss-Seidel iteration with
744	!> 3D-Red-Black decomposition (GS-RB) is used.
745	!------------------------------------------------------------------------------!
746	SUBROUTINE redblack_noopt( f_mg, p_mg )
747
748
749	USE arrays_3d, &
750	ONLY: f1_mg, f2_mg, f3_mg, rho_air_mg
751
752	USE control_parameters, &
753	ONLY: bc_lr_cyc, bc_ns_cyc, grid_level, ibc_p_b, ibc_p_t, inflow_l, &
754	inflow_n, inflow_r, inflow_s, ngsrb, nest_bound_l, &
755	nest_bound_n, nest_bound_r, nest_bound_s, outflow_l, outflow_n, &
756	outflow_r, outflow_s
757
758	USE cpulog, &
759	ONLY: cpu_log, log_point_s
760
761	USE grid_variables, &
762	ONLY: ddx2_mg, ddy2_mg
763
764	USE indices, &
765	ONLY: flags, wall_flags_1, wall_flags_2, wall_flags_3, wall_flags_4, &
766	wall_flags_5, wall_flags_6, wall_flags_7, wall_flags_8, &
767	wall_flags_9, wall_flags_10, nxl_mg, nxr_mg, nys_mg, nyn_mg, &
768	nzb, nzt_mg
769
770	USE kinds
771
772	IMPLICIT NONE
773
774	INTEGER(iwp) :: color !<
775	INTEGER(iwp) :: i !<
776	INTEGER(iwp) :: ic !<
777	INTEGER(iwp) :: j !<
778	INTEGER(iwp) :: jc !<
779	INTEGER(iwp) :: jj !<
780	INTEGER(iwp) :: k !<
781	INTEGER(iwp) :: l !<
782	INTEGER(iwp) :: n !<
783
784	LOGICAL :: unroll !<
785
786	REAL(wp) :: wall_left !<
787	REAL(wp) :: wall_north !<
788	REAL(wp) :: wall_right !<
789	REAL(wp) :: wall_south !<
790	REAL(wp) :: wall_total !<
791	REAL(wp) :: wall_top !<
792
793	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
794	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
795	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f_mg !<
796	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
797	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
798	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: p_mg !<
799
800	l = grid_level
801
802	!
803	!-- Choose flag array of this level
804	SELECT CASE ( l )
805	CASE ( 1 )
806	flags => wall_flags_1
807	CASE ( 2 )
808	flags => wall_flags_2
809	CASE ( 3 )
810	flags => wall_flags_3
811	CASE ( 4 )
812	flags => wall_flags_4
813	CASE ( 5 )
814	flags => wall_flags_5
815	CASE ( 6 )
816	flags => wall_flags_6
817	CASE ( 7 )
818	flags => wall_flags_7
819	CASE ( 8 )
820	flags => wall_flags_8
821	CASE ( 9 )
822	flags => wall_flags_9
823	CASE ( 10 )
824	flags => wall_flags_10
825	END SELECT
826
827	unroll = ( MOD( nyn_mg(l)-nys_mg(l)+1, 4 ) == 0 .AND. &
828	MOD( nxr_mg(l)-nxl_mg(l)+1, 2 ) == 0 )
829
830	DO n = 1, ngsrb
831
832	DO color = 1, 2
833
834	IF ( .NOT. unroll ) THEN
835
836	CALL cpu_log( log_point_s(36), 'redblack_no_unroll_noopt', 'start' )
837
838	!
839	!-- Without unrolling of loops, no cache optimization
840	DO i = nxl_mg(l), nxr_mg(l), 2
841	DO j = nys_mg(l) + 2 - color, nyn_mg(l), 2
842	DO k = nzb+1, nzt_mg(l), 2
843	! p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
844	! ddx2_mg(l) * ( p_mg(k,j,i+1) + p_mg(k,j,i-1) ) &
845	! + ddy2_mg(l) * ( p_mg(k,j+1,i) + p_mg(k,j-1,i) ) &
846	! + f2_mg(k,l) * p_mg(k+1,j,i) &
847	! + f3_mg(k,l) * p_mg(k-1,j,i) - f_mg(k,j,i) &
848	! )
849
850	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
851	rho_air_mg(k,l) * ddx2_mg(l) * &
852	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
853	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
854	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
855	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
856	+ rho_air_mg(k,l) * ddy2_mg(l) * &
857	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
858	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
859	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
860	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
861	+ f2_mg(k,l) * p_mg(k+1,j,i) &
862	+ f3_mg(k,l) * &
863	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
864	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
865	- f_mg(k,j,i) )
866	ENDDO
867	ENDDO
868	ENDDO
869
870	DO i = nxl_mg(l)+1, nxr_mg(l), 2
871	DO j = nys_mg(l) + (color-1), nyn_mg(l), 2
872	DO k = nzb+1, nzt_mg(l), 2
873	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
874	rho_air_mg(k,l) * ddx2_mg(l) * &
875	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
876	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
877	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
878	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
879	+ rho_air_mg(k,l) * ddy2_mg(l) * &
880	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
881	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
882	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
883	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
884	+ f2_mg(k,l) * p_mg(k+1,j,i) &
885	+ f3_mg(k,l) * &
886	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
887	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
888	- f_mg(k,j,i) )
889	ENDDO
890	ENDDO
891	ENDDO
892
893	DO i = nxl_mg(l), nxr_mg(l), 2
894	DO j = nys_mg(l) + (color-1), nyn_mg(l), 2
895	DO k = nzb+2, nzt_mg(l), 2
896	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
897	rho_air_mg(k,l) * ddx2_mg(l) * &
898	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
899	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
900	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
901	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
902	+ rho_air_mg(k,l) * ddy2_mg(l) * &
903	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
904	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
905	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
906	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
907	+ f2_mg(k,l) * p_mg(k+1,j,i) &
908	+ f3_mg(k,l) * &
909	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
910	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
911	- f_mg(k,j,i) )
912	ENDDO
913	ENDDO
914	ENDDO
915
916	DO i = nxl_mg(l)+1, nxr_mg(l), 2
917	DO j = nys_mg(l) + 2 - color, nyn_mg(l), 2
918	DO k = nzb+2, nzt_mg(l), 2
919	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
920	rho_air_mg(k,l) * ddx2_mg(l) * &
921	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
922	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
923	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
924	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
925	+ rho_air_mg(k,l) * ddy2_mg(l) * &
926	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
927	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
928	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
929	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
930	+ f2_mg(k,l) * p_mg(k+1,j,i) &
931	+ f3_mg(k,l) * &
932	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
933	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
934	- f_mg(k,j,i) )
935	ENDDO
936	ENDDO
937	ENDDO
938	CALL cpu_log( log_point_s(36), 'redblack_no_unroll_noopt', 'stop' )
939
940	ELSE
941
942	!
943	!-- Loop unrolling along y, only one i loop for better cache use
944	CALL cpu_log( log_point_s(38), 'redblack_unroll_noopt', 'start' )
945	DO ic = nxl_mg(l), nxr_mg(l), 2
946	DO jc = nys_mg(l), nyn_mg(l), 4
947	i = ic
948	jj = jc+2-color
949	DO k = nzb+1, nzt_mg(l), 2
950	j = jj
951	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
952	rho_air_mg(k,l) * ddx2_mg(l) * &
953	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
954	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
955	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
956	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
957	+ rho_air_mg(k,l) * ddy2_mg(l) * &
958	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
959	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
960	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
961	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
962	+ f2_mg(k,l) * p_mg(k+1,j,i) &
963	+ f3_mg(k,l) * &
964	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
965	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
966	- f_mg(k,j,i) )
967	j = jj+2
968	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
969	rho_air_mg(k,l) * ddx2_mg(l) * &
970	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
971	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
972	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
973	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
974	+ rho_air_mg(k,l) * ddy2_mg(l) * &
975	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
976	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
977	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
978	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
979	+ f2_mg(k,l) * p_mg(k+1,j,i) &
980	+ f3_mg(k,l) * &
981	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
982	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
983	- f_mg(k,j,i) )
984	ENDDO
985
986	i = ic+1
987	jj = jc+color-1
988	DO k = nzb+1, nzt_mg(l), 2
989	j =jj
990	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
991	rho_air_mg(k,l) * ddx2_mg(l) * &
992	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
993	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
994	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
995	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
996	+ rho_air_mg(k,l) * ddy2_mg(l) * &
997	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
998	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
999	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1000	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1001	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1002	+ f3_mg(k,l) * &
1003	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1004	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1005	- f_mg(k,j,i) )
1006	j = jj+2
1007	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
1008	rho_air_mg(k,l) * ddx2_mg(l) * &
1009	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
1010	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
1011	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
1012	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
1013	+ rho_air_mg(k,l) * ddy2_mg(l) * &
1014	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
1015	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
1016	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1017	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1018	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1019	+ f3_mg(k,l) * &
1020	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1021	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1022	- f_mg(k,j,i) )
1023	ENDDO
1024
1025	i = ic
1026	jj = jc+color-1
1027	DO k = nzb+2, nzt_mg(l), 2
1028	j =jj
1029	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
1030	rho_air_mg(k,l) * ddx2_mg(l) * &
1031	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
1032	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
1033	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
1034	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
1035	+ rho_air_mg(k,l) * ddy2_mg(l) * &
1036	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
1037	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
1038	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1039	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1040	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1041	+ f3_mg(k,l) * &
1042	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1043	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1044	- f_mg(k,j,i) )
1045	j = jj+2
1046	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
1047	rho_air_mg(k,l) * ddx2_mg(l) * &
1048	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
1049	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
1050	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
1051	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
1052	+ rho_air_mg(k,l) * ddy2_mg(l) * &
1053	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
1054	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
1055	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1056	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1057	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1058	+ f3_mg(k,l) * &
1059	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1060	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1061	- f_mg(k,j,i) )
1062	ENDDO
1063
1064	i = ic+1
1065	jj = jc+2-color
1066	DO k = nzb+2, nzt_mg(l), 2
1067	j =jj
1068	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
1069	rho_air_mg(k,l) * ddx2_mg(l) * &
1070	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
1071	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
1072	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
1073	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
1074	+ rho_air_mg(k,l) * ddy2_mg(l) * &
1075	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
1076	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
1077	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1078	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1079	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1080	+ f3_mg(k,l) * &
1081	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1082	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1083	- f_mg(k,j,i) )
1084	j = jj+2
1085	p_mg(k,j,i) = 1.0_wp / f1_mg(k,l) * ( &
1086	rho_air_mg(k,l) * ddx2_mg(l) * &
1087	( p_mg(k,j,i+1) + IBITS( flags(k,j,i), 5, 1 ) * &
1088	( p_mg(k,j,i) - p_mg(k,j,i+1) ) + &
1089	p_mg(k,j,i-1) + IBITS( flags(k,j,i), 4, 1 ) * &
1090	( p_mg(k,j,i) - p_mg(k,j,i-1) ) ) &
1091	+ rho_air_mg(k,l) * ddy2_mg(l) * &
1092	( p_mg(k,j+1,i) + IBITS( flags(k,j,i), 3, 1 ) * &
1093	( p_mg(k,j,i) - p_mg(k,j+1,i) ) + &
1094	p_mg(k,j-1,i) + IBITS( flags(k,j,i), 2, 1 ) * &
1095	( p_mg(k,j,i) - p_mg(k,j-1,i) ) ) &
1096	+ f2_mg(k,l) * p_mg(k+1,j,i) &
1097	+ f3_mg(k,l) * &
1098	( p_mg(k-1,j,i) + IBITS( flags(k,j,i), 0, 1 ) * &
1099	( p_mg(k,j,i) - p_mg(k-1,j,i) ) ) &
1100	- f_mg(k,j,i) )
1101	ENDDO
1102
1103	ENDDO
1104	ENDDO
1105	CALL cpu_log( log_point_s(38), 'redblack_unroll_noopt', 'stop' )
1106
1107	ENDIF
1108
1109	!
1110	!-- Horizontal boundary conditions
1111	CALL exchange_horiz( p_mg, 1 )
1112
1113	IF ( .NOT. bc_lr_cyc ) THEN
1114	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
1115	p_mg(:,:,nxl_mg(l)-1) = p_mg(:,:,nxl_mg(l))
1116	ENDIF
1117	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
1118	p_mg(:,:,nxr_mg(l)+1) = p_mg(:,:,nxr_mg(l))
1119	ENDIF
1120	ENDIF
1121
1122	IF ( .NOT. bc_ns_cyc ) THEN
1123	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
1124	p_mg(:,nyn_mg(l)+1,:) = p_mg(:,nyn_mg(l),:)
1125	ENDIF
1126	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
1127	p_mg(:,nys_mg(l)-1,:) = p_mg(:,nys_mg(l),:)
1128	ENDIF
1129	ENDIF
1130
1131	!
1132	!-- Bottom and top boundary conditions
1133	IF ( ibc_p_b == 1 ) THEN
1134	p_mg(nzb,:,: ) = p_mg(nzb+1,:,:)
1135	ELSE
1136	p_mg(nzb,:,: ) = 0.0_wp
1137	ENDIF
1138
1139	IF ( ibc_p_t == 1 ) THEN
1140	p_mg(nzt_mg(l)+1,:,: ) = p_mg(nzt_mg(l),:,:)
1141	ELSE
1142	p_mg(nzt_mg(l)+1,:,: ) = 0.0_wp
1143	ENDIF
1144
1145	ENDDO
1146
1147	ENDDO
1148
1149	!
1150	!-- Set pressure within topography and at the topography surfaces
1151	!$OMP PARALLEL PRIVATE (i,j,k,wall_left,wall_north,wall_right,wall_south,wall_top,wall_total)
1152	!$OMP DO
1153	DO i = nxl_mg(l), nxr_mg(l)
1154	DO j = nys_mg(l), nyn_mg(l)
1155	DO k = nzb, nzt_mg(l)
1156	!
1157	!-- First, set pressure inside topography to zero
1158	p_mg(k,j,i) = p_mg(k,j,i) * ( 1.0_wp - IBITS( flags(k,j,i), 6, 1 ) )
1159	!
1160	!-- Second, determine if the gridpoint inside topography is adjacent
1161	!-- to a wall and set its value to a value given by the average of
1162	!-- those values obtained from Neumann boundary condition
1163	wall_left = IBITS( flags(k,j,i-1), 5, 1 )
1164	wall_right = IBITS( flags(k,j,i+1), 4, 1 )
1165	wall_south = IBITS( flags(k,j-1,i), 3, 1 )
1166	wall_north = IBITS( flags(k,j+1,i), 2, 1 )
1167	wall_top = IBITS( flags(k+1,j,i), 0, 1 )
1168	wall_total = wall_left + wall_right + wall_south + wall_north + &
1169	wall_top
1170
1171	IF ( wall_total > 0.0_wp ) THEN
1172	p_mg(k,j,i) = 1.0_wp / wall_total * &
1173	( wall_left * p_mg(k,j,i-1) + &
1174	wall_right * p_mg(k,j,i+1) + &
1175	wall_south * p_mg(k,j-1,i) + &
1176	wall_north * p_mg(k,j+1,i) + &
1177	wall_top * p_mg(k+1,j,i) )
1178	ENDIF
1179	ENDDO
1180	ENDDO
1181	ENDDO
1182	!$OMP END PARALLEL
1183
1184	!
1185	!-- One more time horizontal boundary conditions
1186	CALL exchange_horiz( p_mg, 1)
1187
1188
1189	END SUBROUTINE redblack_noopt
1190
1191
1192
1193	!------------------------------------------------------------------------------!
1194	! Description:
1195	! ------------
1196	!> Gather subdomain data from all PEs.
1197	!------------------------------------------------------------------------------!
1198	SUBROUTINE mg_gather_noopt( f2, f2_sub )
1199
1200	USE control_parameters, &
1201	ONLY: grid_level
1202
1203	USE cpulog, &
1204	ONLY: cpu_log, log_point_s
1205
1206	USE indices, &
1207	ONLY: mg_loc_ind, nxl_mg, nxr_mg, nys_mg, nyn_mg, nzb, nzt_mg
1208
1209	USE kinds
1210
1211	USE pegrid
1212
1213	IMPLICIT NONE
1214
1215	INTEGER(iwp) :: i !<
1216	INTEGER(iwp) :: il !<
1217	INTEGER(iwp) :: ir !<
1218	INTEGER(iwp) :: j !<
1219	INTEGER(iwp) :: jn !<
1220	INTEGER(iwp) :: js !<
1221	INTEGER(iwp) :: k !<
1222	INTEGER(iwp) :: nwords !<
1223
1224	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1225	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1226	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f2 !<
1227	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1228	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1229	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f2_l !<
1230
1231	REAL(wp), DIMENSION(nzb:mg_loc_ind(5,myid)+1, &
1232	mg_loc_ind(3,myid)-1:mg_loc_ind(4,myid)+1, &
1233	mg_loc_ind(1,myid)-1:mg_loc_ind(2,myid)+1) :: f2_sub !<
1234
1235
1236	#if defined( __parallel )
1237	CALL cpu_log( log_point_s(34), 'mg_gather_noopt', 'start' )
1238
1239	f2_l = 0.0_wp
1240
1241	!
1242	!-- Store the local subdomain array on the total array
1243	js = mg_loc_ind(3,myid)
1244	IF ( south_border_pe ) js = js - 1
1245	jn = mg_loc_ind(4,myid)
1246	IF ( north_border_pe ) jn = jn + 1
1247	il = mg_loc_ind(1,myid)
1248	IF ( left_border_pe ) il = il - 1
1249	ir = mg_loc_ind(2,myid)
1250	IF ( right_border_pe ) ir = ir + 1
1251	DO i = il, ir
1252	DO j = js, jn
1253	DO k = nzb, nzt_mg(grid_level)+1
1254	f2_l(k,j,i) = f2_sub(k,j,i)
1255	ENDDO
1256	ENDDO
1257	ENDDO
1258
1259	!
1260	!-- Find out the number of array elements of the total array
1261	nwords = SIZE( f2 )
1262
1263	!
1264	!-- Gather subdomain data from all PEs
1265	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
1266	CALL MPI_ALLREDUCE( f2_l(nzb,nys_mg(grid_level)-1,nxl_mg(grid_level)-1), &
1267	f2(nzb,nys_mg(grid_level)-1,nxl_mg(grid_level)-1), &
1268	nwords, MPI_REAL, MPI_SUM, comm2d, ierr )
1269
1270	CALL cpu_log( log_point_s(34), 'mg_gather_noopt', 'stop' )
1271	#endif
1272
1273	END SUBROUTINE mg_gather_noopt
1274
1275
1276
1277	!------------------------------------------------------------------------------!
1278	! Description:
1279	! ------------
1280	!> @todo It may be possible to improve the speed of this routine by using
1281	!> non-blocking communication
1282	!------------------------------------------------------------------------------!
1283	SUBROUTINE mg_scatter_noopt( p2, p2_sub )
1284
1285	USE control_parameters, &
1286	ONLY: grid_level
1287
1288	USE cpulog, &
1289	ONLY: cpu_log, log_point_s
1290
1291	USE indices, &
1292	ONLY: mg_loc_ind, nxl_mg, nxr_mg, nys_mg, nyn_mg, nzb, nzt_mg
1293
1294	USE kinds
1295
1296	USE pegrid
1297
1298	IMPLICIT NONE
1299
1300	INTEGER(iwp) :: nwords !<
1301
1302	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level-1)+1, &
1303	nys_mg(grid_level-1)-1:nyn_mg(grid_level-1)+1, &
1304	nxl_mg(grid_level-1)-1:nxr_mg(grid_level-1)+1) :: p2 !<
1305
1306	REAL(wp), DIMENSION(nzb:mg_loc_ind(5,myid)+1, &
1307	mg_loc_ind(3,myid)-1:mg_loc_ind(4,myid)+1, &
1308	mg_loc_ind(1,myid)-1:mg_loc_ind(2,myid)+1) :: p2_sub !<
1309
1310	!
1311	!-- Find out the number of array elements of the subdomain array
1312	nwords = SIZE( p2_sub )
1313
1314	#if defined( __parallel )
1315	CALL cpu_log( log_point_s(35), 'mg_scatter_noopt', 'start' )
1316
1317	p2_sub = p2(:,mg_loc_ind(3,myid)-1:mg_loc_ind(4,myid)+1, &
1318	mg_loc_ind(1,myid)-1:mg_loc_ind(2,myid)+1)
1319
1320	CALL cpu_log( log_point_s(35), 'mg_scatter_noopt', 'stop' )
1321	#endif
1322
1323	END SUBROUTINE mg_scatter_noopt
1324
1325
1326	!------------------------------------------------------------------------------!
1327	! Description:
1328	! ------------
1329	!> This is where the multigrid technique takes place. V- and W- Cycle are
1330	!> implemented and steered by the parameter "gamma". Parameter "nue" determines
1331	!> the convergence of the multigrid iterative solution. There are nue times
1332	!> RB-GS iterations. It should be set to "1" or "2", considering the time effort
1333	!> one would like to invest. Last choice shows a very good converging factor,
1334	!> but leads to an increase in computing time.
1335	!------------------------------------------------------------------------------!
1336	RECURSIVE SUBROUTINE next_mg_level_noopt( f_mg, p_mg, p3, r )
1337
1338	USE control_parameters, &
1339	ONLY: bc_lr_dirrad, bc_lr_raddir, bc_ns_dirrad, bc_ns_raddir, &
1340	gamma_mg, grid_level, grid_level_count, ibc_p_b, ibc_p_t, &
1341	inflow_l, inflow_n, inflow_r, inflow_s, maximum_grid_level, &
1342	mg_switch_to_pe0_level, mg_switch_to_pe0, nest_domain, &
1343	nest_bound_l, nest_bound_n, nest_bound_r, nest_bound_s, ngsrb, &
1344	outflow_l, outflow_n, outflow_r, outflow_s
1345
1346
1347	USE indices, &
1348	ONLY: mg_loc_ind, nxl, nxl_mg, nxr, nxr_mg, nys, nys_mg, nyn, &
1349	nyn_mg, nzb, nzt, nzt_mg
1350
1351	USE kinds
1352
1353	USE pegrid
1354
1355	IMPLICIT NONE
1356
1357	INTEGER(iwp) :: i !<
1358	INTEGER(iwp) :: j !<
1359	INTEGER(iwp) :: k !<
1360	INTEGER(iwp) :: nxl_mg_save !<
1361	INTEGER(iwp) :: nxr_mg_save !<
1362	INTEGER(iwp) :: nyn_mg_save !<
1363	INTEGER(iwp) :: nys_mg_save !<
1364	INTEGER(iwp) :: nzt_mg_save !<
1365
1366	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1367	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1368	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: f_mg !<
1369	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1370	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1371	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: p_mg !<
1372	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1373	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1374	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: p3 !<
1375	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level)+1, &
1376	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1377	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) :: r !<
1378
1379	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level-1)+1, &
1380	nys_mg(grid_level-1)-1:nyn_mg(grid_level-1)+1, &
1381	nxl_mg(grid_level-1)-1:nxr_mg(grid_level-1)+1) :: f2 !<
1382	REAL(wp), DIMENSION(nzb:nzt_mg(grid_level-1)+1, &
1383	nys_mg(grid_level-1)-1:nyn_mg(grid_level-1)+1, &
1384	nxl_mg(grid_level-1)-1:nxr_mg(grid_level-1)+1) :: p2 !<
1385
1386	REAL(wp), DIMENSION(:,:,:), ALLOCATABLE :: f2_sub !<
1387	REAL(wp), DIMENSION(:,:,:), ALLOCATABLE :: p2_sub !<
1388
1389	!
1390	!-- Restriction to the coarsest grid
1391	10 IF ( grid_level == 1 ) THEN
1392
1393	!
1394	!-- Solution on the coarsest grid. Double the number of Gauss-Seidel
1395	!-- iterations in order to get a more accurate solution.
1396	ngsrb = 2 * ngsrb
1397
1398	CALL redblack_noopt( f_mg, p_mg )
1399
1400	ngsrb = ngsrb / 2
1401
1402
1403	ELSEIF ( grid_level /= 1 ) THEN
1404
1405	grid_level_count(grid_level) = grid_level_count(grid_level) + 1
1406
1407	!
1408	!-- Solution on the actual grid level
1409	CALL redblack_noopt( f_mg, p_mg )
1410
1411	!
1412	!-- Determination of the actual residual
1413	CALL resid_noopt( f_mg, p_mg, r )
1414
1415	!
1416	!-- Restriction of the residual (finer grid values!) to the next coarser
1417	!-- grid. Therefore, the grid level has to be decremented now. nxl..nzt have
1418	!-- to be set to the coarse grid values, because these variables are needed
1419	!-- for the exchange of ghost points in routine exchange_horiz
1420	grid_level = grid_level - 1
1421	nxl = nxl_mg(grid_level)
1422	nys = nys_mg(grid_level)
1423	nxr = nxr_mg(grid_level)
1424	nyn = nyn_mg(grid_level)
1425	nzt = nzt_mg(grid_level)
1426
1427	IF ( grid_level == mg_switch_to_pe0_level ) THEN
1428
1429	!
1430	!-- From this level on, calculations are done on PE0 only.
1431	!-- First, carry out restriction on the subdomain.
1432	!-- Therefore, indices of the level have to be changed to subdomain values
1433	!-- in between (otherwise, the restrict routine would expect
1434	!-- the gathered array)
1435
1436	nxl_mg_save = nxl_mg(grid_level)
1437	nxr_mg_save = nxr_mg(grid_level)
1438	nys_mg_save = nys_mg(grid_level)
1439	nyn_mg_save = nyn_mg(grid_level)
1440	nzt_mg_save = nzt_mg(grid_level)
1441	nxl_mg(grid_level) = mg_loc_ind(1,myid)
1442	nxr_mg(grid_level) = mg_loc_ind(2,myid)
1443	nys_mg(grid_level) = mg_loc_ind(3,myid)
1444	nyn_mg(grid_level) = mg_loc_ind(4,myid)
1445	nzt_mg(grid_level) = mg_loc_ind(5,myid)
1446	nxl = mg_loc_ind(1,myid)
1447	nxr = mg_loc_ind(2,myid)
1448	nys = mg_loc_ind(3,myid)
1449	nyn = mg_loc_ind(4,myid)
1450	nzt = mg_loc_ind(5,myid)
1451
1452	ALLOCATE( f2_sub(nzb:nzt_mg(grid_level)+1, &
1453	nys_mg(grid_level)-1:nyn_mg(grid_level)+1, &
1454	nxl_mg(grid_level)-1:nxr_mg(grid_level)+1) )
1455
1456	CALL restrict_noopt( f2_sub, r )
1457
1458	!
1459	!-- Restore the correct indices of this level
1460	nxl_mg(grid_level) = nxl_mg_save
1461	nxr_mg(grid_level) = nxr_mg_save
1462	nys_mg(grid_level) = nys_mg_save
1463	nyn_mg(grid_level) = nyn_mg_save
1464	nzt_mg(grid_level) = nzt_mg_save
1465	nxl = nxl_mg(grid_level)
1466	nxr = nxr_mg(grid_level)
1467	nys = nys_mg(grid_level)
1468	nyn = nyn_mg(grid_level)
1469	nzt = nzt_mg(grid_level)
1470	!
1471	!-- Gather all arrays from the subdomains on PE0
1472	CALL mg_gather_noopt( f2, f2_sub )
1473
1474	!
1475	!-- Set switch for routine exchange_horiz, that no ghostpoint exchange
1476	!-- has to be carried out from now on
1477	mg_switch_to_pe0 = .TRUE.
1478
1479	!
1480	!-- In case of non-cyclic lateral boundary conditions, both in- and
1481	!-- outflow conditions have to be used on all PEs after the switch,
1482	!-- because then they have the total domain.
1483	IF ( bc_lr_dirrad ) THEN
1484	inflow_l = .TRUE.
1485	inflow_r = .FALSE.
1486	outflow_l = .FALSE.
1487	outflow_r = .TRUE.
1488	ELSEIF ( bc_lr_raddir ) THEN
1489	inflow_l = .FALSE.
1490	inflow_r = .TRUE.
1491	outflow_l = .TRUE.
1492	outflow_r = .FALSE.
1493	ELSEIF ( nest_domain ) THEN
1494	nest_bound_l = .TRUE.
1495	nest_bound_r = .TRUE.
1496	ENDIF
1497
1498	IF ( bc_ns_dirrad ) THEN
1499	inflow_n = .TRUE.
1500	inflow_s = .FALSE.
1501	outflow_n = .FALSE.
1502	outflow_s = .TRUE.
1503	ELSEIF ( bc_ns_raddir ) THEN
1504	inflow_n = .FALSE.
1505	inflow_s = .TRUE.
1506	outflow_n = .TRUE.
1507	outflow_s = .FALSE.
1508	ELSEIF ( nest_domain ) THEN
1509	nest_bound_s = .TRUE.
1510	nest_bound_n = .TRUE.
1511	ENDIF
1512
1513	DEALLOCATE( f2_sub )
1514
1515	ELSE
1516
1517	CALL restrict_noopt( f2, r )
1518
1519	ENDIF
1520
1521	p2 = 0.0_wp
1522
1523	!
1524	!-- Repeat the same procedure till the coarsest grid is reached
1525	CALL next_mg_level_noopt( f2, p2, p3, r )
1526
1527	ENDIF
1528
1529	!
1530	!-- Now follows the prolongation
1531	IF ( grid_level >= 2 ) THEN
1532
1533	!
1534	!-- Prolongation of the new residual. The values are transferred
1535	!-- from the coarse to the next finer grid.
1536	IF ( grid_level == mg_switch_to_pe0_level+1 ) THEN
1537
1538	#if defined( __parallel )
1539	!
1540	!-- At this level, the new residual first has to be scattered from
1541	!-- PE0 to the other PEs
1542	ALLOCATE( p2_sub(nzb:mg_loc_ind(5,myid)+1, &
1543	mg_loc_ind(3,myid)-1:mg_loc_ind(4,myid)+1, &
1544	mg_loc_ind(1,myid)-1:mg_loc_ind(2,myid)+1) )
1545
1546	CALL mg_scatter_noopt( p2, p2_sub )
1547
1548	!
1549	!-- Therefore, indices of the previous level have to be changed to
1550	!-- subdomain values in between (otherwise, the prolong routine would
1551	!-- expect the gathered array)
1552	nxl_mg_save = nxl_mg(grid_level-1)
1553	nxr_mg_save = nxr_mg(grid_level-1)
1554	nys_mg_save = nys_mg(grid_level-1)
1555	nyn_mg_save = nyn_mg(grid_level-1)
1556	nzt_mg_save = nzt_mg(grid_level-1)
1557	nxl_mg(grid_level-1) = mg_loc_ind(1,myid)
1558	nxr_mg(grid_level-1) = mg_loc_ind(2,myid)
1559	nys_mg(grid_level-1) = mg_loc_ind(3,myid)
1560	nyn_mg(grid_level-1) = mg_loc_ind(4,myid)
1561	nzt_mg(grid_level-1) = mg_loc_ind(5,myid)
1562
1563	!
1564	!-- Set switch for routine exchange_horiz, that ghostpoint exchange
1565	!-- has to be carried again out from now on
1566	mg_switch_to_pe0 = .FALSE.
1567
1568	!
1569	!-- For non-cyclic lateral boundary conditions and in case of nesting,
1570	!-- restore the in-/outflow conditions.
1571	inflow_l = .FALSE.; inflow_r = .FALSE.
1572	inflow_n = .FALSE.; inflow_s = .FALSE.
1573	outflow_l = .FALSE.; outflow_r = .FALSE.
1574	outflow_n = .FALSE.; outflow_s = .FALSE.
1575	!
1576	!-- In case of nesting, restore lateral boundary conditions
1577	IF ( nest_domain ) THEN
1578	nest_bound_l = .FALSE.
1579	nest_bound_r = .FALSE.
1580	nest_bound_s = .FALSE.
1581	nest_bound_n = .FALSE.
1582	ENDIF
1583
1584	IF ( pleft == MPI_PROC_NULL ) THEN
1585	IF ( bc_lr_dirrad ) THEN
1586	inflow_l = .TRUE.
1587	ELSEIF ( bc_lr_raddir ) THEN
1588	outflow_l = .TRUE.
1589	ELSEIF ( nest_domain ) THEN
1590	nest_bound_l = .TRUE.
1591	ENDIF
1592	ENDIF
1593
1594	IF ( pright == MPI_PROC_NULL ) THEN
1595	IF ( bc_lr_dirrad ) THEN
1596	outflow_r = .TRUE.
1597	ELSEIF ( bc_lr_raddir ) THEN
1598	inflow_r = .TRUE.
1599	ELSEIF ( nest_domain ) THEN
1600	nest_bound_r = .TRUE.
1601	ENDIF
1602	ENDIF
1603
1604	IF ( psouth == MPI_PROC_NULL ) THEN
1605	IF ( bc_ns_dirrad ) THEN
1606	outflow_s = .TRUE.
1607	ELSEIF ( bc_ns_raddir ) THEN
1608	inflow_s = .TRUE.
1609	ELSEIF ( nest_domain ) THEN
1610	nest_bound_s = .TRUE.
1611	ENDIF
1612	ENDIF
1613
1614	IF ( pnorth == MPI_PROC_NULL ) THEN
1615	IF ( bc_ns_dirrad ) THEN
1616	inflow_n = .TRUE.
1617	ELSEIF ( bc_ns_raddir ) THEN
1618	outflow_n = .TRUE.
1619	ELSEIF ( nest_domain ) THEN
1620	nest_bound_n = .TRUE.
1621	ENDIF
1622	ENDIF
1623
1624	CALL prolong_noopt( p2_sub, p3 )
1625
1626	!
1627	!-- Restore the correct indices of the previous level
1628	nxl_mg(grid_level-1) = nxl_mg_save
1629	nxr_mg(grid_level-1) = nxr_mg_save
1630	nys_mg(grid_level-1) = nys_mg_save
1631	nyn_mg(grid_level-1) = nyn_mg_save
1632	nzt_mg(grid_level-1) = nzt_mg_save
1633
1634	DEALLOCATE( p2_sub )
1635	#endif
1636
1637	ELSE
1638
1639	CALL prolong_noopt( p2, p3 )
1640
1641	ENDIF
1642
1643	!
1644	!-- Computation of the new pressure correction. Therefore,
1645	!-- values from prior grids are added up automatically stage by stage.
1646	DO i = nxl_mg(grid_level)-1, nxr_mg(grid_level)+1
1647	DO j = nys_mg(grid_level)-1, nyn_mg(grid_level)+1
1648	DO k = nzb, nzt_mg(grid_level)+1
1649	p_mg(k,j,i) = p_mg(k,j,i) + p3(k,j,i)
1650	ENDDO
1651	ENDDO
1652	ENDDO
1653
1654	!
1655	!-- Relaxation of the new solution
1656	CALL redblack_noopt( f_mg, p_mg )
1657
1658	ENDIF
1659
1660
1661	!
1662	!-- The following few lines serve the steering of the multigrid scheme
1663	IF ( grid_level == maximum_grid_level ) THEN
1664
1665	GOTO 20
1666
1667	ELSEIF ( grid_level /= maximum_grid_level .AND. grid_level /= 1 .AND. &
1668	grid_level_count(grid_level) /= gamma_mg ) THEN
1669
1670	GOTO 10
1671
1672	ENDIF
1673
1674	!
1675	!-- Reset counter for the next call of poismg_noopt
1676	grid_level_count(grid_level) = 0
1677
1678	!
1679	!-- Continue with the next finer level. nxl..nzt have to be
1680	!-- set to the finer grid values, because these variables are needed for the
1681	!-- exchange of ghost points in routine exchange_horiz
1682	grid_level = grid_level + 1
1683	nxl = nxl_mg(grid_level)
1684	nxr = nxr_mg(grid_level)
1685	nys = nys_mg(grid_level)
1686	nyn = nyn_mg(grid_level)
1687	nzt = nzt_mg(grid_level)
1688
1689	20 CONTINUE
1690
1691	END SUBROUTINE next_mg_level_noopt

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