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source: palm/trunk/SOURCE/pres.f90 @ 4237

Last change on this file since 4237 was 4182, checked in by scharf, 5 years ago
corrected "Former revisions" section minor formatting in "Former revisions" section added "Author" section
Property svn:keywords set to `Id`
File size: 29.9 KB

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[1682]	1	!> @file pres.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	!
[3655]	17	! Copyright 1997-2019 Leibniz Universitaet Hannover
[2000]	18	!------------------------------------------------------------------------------!
[1036]	19	!
[484]	20	! Current revisions:
[1212]	21	! ------------------
[1932]	22	!
[3183]	23	!
[1919]	24	! Former revisions:
	25	! -----------------
[3016]	26	! $Id: pres.f90 4182 2019-08-22 15:20:23Z knoop $
[4182]	27	! Corrected "Former revisions" section
	28	!
	29	! 4015 2019-06-05 13:25:35Z raasch
[4015]	30	! variable child_domain_nvn eliminated
	31	!
	32	! 3849 2019-04-01 16:35:16Z knoop
[3634]	33	! OpenACC port for SPEC
[1919]	34	!
[4182]	35	! Revision 1.1 1997/07/24 11:24:44 raasch
	36	! Initial revision
	37	!
	38	!
[1]	39	! Description:
	40	! ------------
[1682]	41	!> Compute the divergence of the provisional velocity field. Solve the Poisson
	42	!> equation for the perturbation pressure. Compute the final velocities using
	43	!> this perturbation pressure. Compute the remaining divergence.
[1]	44	!------------------------------------------------------------------------------!
[1682]	45	SUBROUTINE pres
	46
[1]	47
[1320]	48	USE arrays_3d, &
[2037]	49	ONLY: d, ddzu, ddzu_pres, ddzw, dzw, p, p_loc, rho_air, rho_air_zw, &
	50	tend, u, v, w
[1320]	51
	52	USE control_parameters, &
[3182]	53	ONLY: bc_lr_cyc, bc_ns_cyc, bc_radiation_l, bc_radiation_n, &
	54	bc_radiation_r, bc_radiation_s, child_domain, &
	55	conserve_volume_flow, coupling_mode, &
[3012]	56	dt_3d, gathered_size, ibc_p_b, ibc_p_t, &
	57	intermediate_timestep_count, intermediate_timestep_count_max, &
[3347]	58	mg_switch_to_pe0_level, nesting_offline, &
	59	psolver, subdomain_size, &
[3182]	60	topography, volume_flow, volume_flow_area, volume_flow_initial
[1320]	61
	62	USE cpulog, &
	63	ONLY: cpu_log, log_point, log_point_s
	64
	65	USE grid_variables, &
	66	ONLY: ddx, ddy
	67
	68	USE indices, &
	69	ONLY: nbgp, ngp_2dh_outer, nx, nxl, nxlg, nxl_mg, nxr, nxrg, nxr_mg, &
[2232]	70	ny, nys, nysg, nys_mg, nyn, nyng, nyn_mg, nzb, nzt, nzt_mg, &
	71	wall_flags_0
[1320]	72
	73	USE kinds
	74
[1]	75	USE pegrid
[1933]	76
	77	USE pmc_interface, &
	78	ONLY: nesting_mode
[1]	79
[1320]	80	USE poisfft_mod, &
	81	ONLY: poisfft
	82
[1575]	83	USE poismg_mod
	84
[2696]	85	USE poismg_noopt_mod
	86
[1320]	87	USE statistics, &
	88	ONLY: statistic_regions, sums_divnew_l, sums_divold_l, weight_pres, &
	89	weight_substep
	90
[2232]	91	USE surface_mod, &
	92	ONLY : bc_h
	93
[1]	94	IMPLICIT NONE
	95
[1682]	96	INTEGER(iwp) :: i !<
	97	INTEGER(iwp) :: j !<
	98	INTEGER(iwp) :: k !<
[2232]	99	INTEGER(iwp) :: m !<
[1]	100
[1682]	101	REAL(wp) :: ddt_3d !<
[1918]	102	REAL(wp) :: d_weight_pres !<
[1682]	103	REAL(wp) :: localsum !<
	104	REAL(wp) :: threadsum !<
[1918]	105	REAL(wp) :: weight_pres_l !<
[1929]	106	REAL(wp) :: weight_substep_l !<
[1]	107
[1762]	108	REAL(wp), DIMENSION(1:3) :: volume_flow_l !<
	109	REAL(wp), DIMENSION(1:3) :: volume_flow_offset !<
[1682]	110	REAL(wp), DIMENSION(1:nzt) :: w_l !<
	111	REAL(wp), DIMENSION(1:nzt) :: w_l_l !<
[1]	112
	113
	114	CALL cpu_log( log_point(8), 'pres', 'start' )
	115
[1918]	116	!
	117	!-- Calculate quantities to be used locally
[1342]	118	ddt_3d = 1.0_wp / dt_3d
[1918]	119	IF ( intermediate_timestep_count == 0 ) THEN
	120	!
	121	!-- If pres is called before initial time step
[1929]	122	weight_pres_l = 1.0_wp
	123	d_weight_pres = 1.0_wp
	124	weight_substep_l = 1.0_wp
[1918]	125	ELSE
[1929]	126	weight_pres_l = weight_pres(intermediate_timestep_count)
	127	d_weight_pres = 1.0_wp / weight_pres(intermediate_timestep_count)
	128	weight_substep_l = weight_substep(intermediate_timestep_count)
[1918]	129	ENDIF
[85]	130
[1]	131	!
[707]	132	!-- Multigrid method expects array d to have one ghost layer.
	133	!--
[1575]	134	IF ( psolver(1:9) == 'multigrid' ) THEN
[667]	135
[1]	136	DEALLOCATE( d )
[667]	137	ALLOCATE( d(nzb:nzt+1,nys-1:nyn+1,nxl-1:nxr+1) )
[707]	138
	139	!
	140	!-- Since p is later used to hold the weighted average of the substeps, it
	141	!-- cannot be used in the iterative solver. Therefore, its initial value is
	142	!-- stored on p_loc, which is then iteratively advanced in every substep.
[1762]	143	IF ( intermediate_timestep_count <= 1 ) THEN
[707]	144	DO i = nxl-1, nxr+1
	145	DO j = nys-1, nyn+1
	146	DO k = nzb, nzt+1
	147	p_loc(k,j,i) = p(k,j,i)
	148	ENDDO
	149	ENDDO
	150	ENDDO
[667]	151	ENDIF
	152
[1918]	153	ELSEIF ( psolver == 'sor' .AND. intermediate_timestep_count <= 1 ) THEN
[707]	154
	155	!
	156	!-- Since p is later used to hold the weighted average of the substeps, it
	157	!-- cannot be used in the iterative solver. Therefore, its initial value is
	158	!-- stored on p_loc, which is then iteratively advanced in every substep.
	159	p_loc = p
	160
[1]	161	ENDIF
	162
	163	!
[75]	164	!-- Conserve the volume flow at the outflow in case of non-cyclic lateral
	165	!-- boundary conditions
[106]	166	!-- WARNING: so far, this conservation does not work at the left/south
	167	!-- boundary if the topography at the inflow differs from that at the
	168	!-- outflow! For this case, volume_flow_area needs adjustment!
	169	!
	170	!-- Left/right
[3182]	171	IF ( conserve_volume_flow .AND. ( bc_radiation_l .OR. &
	172	bc_radiation_r ) ) THEN
[680]	173
[1342]	174	volume_flow(1) = 0.0_wp
	175	volume_flow_l(1) = 0.0_wp
[106]	176
[3182]	177	IF ( bc_radiation_l ) THEN
[106]	178	i = 0
[3182]	179	ELSEIF ( bc_radiation_r ) THEN
[106]	180	i = nx+1
	181	ENDIF
	182
	183	DO j = nys, nyn
	184	!
	185	!-- Sum up the volume flow through the south/north boundary
[2232]	186	DO k = nzb+1, nzt
	187	volume_flow_l(1) = volume_flow_l(1) + u(k,j,i) * dzw(k) &
	188	* MERGE( 1.0_wp, 0.0_wp, &
	189	BTEST( wall_flags_0(k,j,i), 1 ) &
	190	)
[106]	191	ENDDO
	192	ENDDO
	193
	194	#if defined( __parallel )
[680]	195	IF ( collective_wait ) CALL MPI_BARRIER( comm1dy, ierr )
[106]	196	CALL MPI_ALLREDUCE( volume_flow_l(1), volume_flow(1), 1, MPI_REAL, &
	197	MPI_SUM, comm1dy, ierr )
	198	#else
	199	volume_flow = volume_flow_l
	200	#endif
[709]	201	volume_flow_offset(1) = ( volume_flow_initial(1) - volume_flow(1) ) &
[106]	202	/ volume_flow_area(1)
	203
[667]	204	DO j = nysg, nyng
[2232]	205	DO k = nzb+1, nzt
	206	u(k,j,i) = u(k,j,i) + volume_flow_offset(1) &
	207	* MERGE( 1.0_wp, 0.0_wp, &
	208	BTEST( wall_flags_0(k,j,i), 1 ) &
	209	)
[106]	210	ENDDO
	211	ENDDO
	212
	213	ENDIF
	214
	215	!
	216	!-- South/north
[3182]	217	IF ( conserve_volume_flow .AND. ( bc_radiation_n .OR. bc_radiation_s ) ) THEN
[106]	218
[1342]	219	volume_flow(2) = 0.0_wp
	220	volume_flow_l(2) = 0.0_wp
[75]	221
[3182]	222	IF ( bc_radiation_s ) THEN
[106]	223	j = 0
[3182]	224	ELSEIF ( bc_radiation_n ) THEN
[75]	225	j = ny+1
[106]	226	ENDIF
	227
	228	DO i = nxl, nxr
[75]	229	!
[106]	230	!-- Sum up the volume flow through the south/north boundary
[2232]	231	DO k = nzb+1, nzt
	232	volume_flow_l(2) = volume_flow_l(2) + v(k,j,i) * dzw(k) &
	233	* MERGE( 1.0_wp, 0.0_wp, &
	234	BTEST( wall_flags_0(k,j,i), 2 ) &
	235	)
[75]	236	ENDDO
[106]	237	ENDDO
	238
[75]	239	#if defined( __parallel )
[680]	240	IF ( collective_wait ) CALL MPI_BARRIER( comm1dx, ierr )
[75]	241	CALL MPI_ALLREDUCE( volume_flow_l(2), volume_flow(2), 1, MPI_REAL, &
	242	MPI_SUM, comm1dx, ierr )
	243	#else
	244	volume_flow = volume_flow_l
	245	#endif
	246	volume_flow_offset(2) = ( volume_flow_initial(2) - volume_flow(2) ) &
[106]	247	/ volume_flow_area(2)
[75]	248
[667]	249	DO i = nxlg, nxrg
[2232]	250	DO k = nzb+1, nzt
	251	v(k,j,i) = v(k,j,i) + volume_flow_offset(2) &
	252	* MERGE( 1.0_wp, 0.0_wp, &
	253	BTEST( wall_flags_0(k,j,i), 2 ) &
	254	)
[75]	255	ENDDO
[106]	256	ENDDO
[75]	257
	258	ENDIF
	259
[76]	260	!
[4015]	261	!-- Remove mean vertical velocity in case that Neumann conditions are used both at bottom and top
	262	!-- boundary. With Neumann conditions at both vertical boundaries, the solver cannot remove
	263	!-- mean vertical velocities. They should be removed, because incompressibility requires that
	264	!-- the vertical gradient of vertical velocity is zero. Since w=0 at the solid surface, it must be
	265	!-- zero everywhere.
	266	!-- This must not be done in case of a 3d-nesting child domain, because a mean vertical velocity
	267	!-- can physically exist in such a domain.
	268	!-- Also in case of offline nesting, mean vertical velocities may exist (and must not be removed),
	269	!-- caused by horizontal divergence/convergence of the large scale flow that is prescribed at the
	270	!-- side boundaries.
	271	!-- The removal cannot be done before the first initial time step because ngp_2dh_outer
[1918]	272	!-- is not yet known then.
[4015]	273	IF ( ibc_p_b == 1 .AND. ibc_p_t == 1 .AND. .NOT. nesting_offline &
	274	.AND. .NOT. ( child_domain .AND. nesting_mode /= 'vertical' ) &
	275	.AND. intermediate_timestep_count /= 0 ) &
[1918]	276	THEN
	277	w_l = 0.0_wp; w_l_l = 0.0_wp
	278	DO i = nxl, nxr
	279	DO j = nys, nyn
[2232]	280	DO k = nzb+1, nzt
[4015]	281	w_l_l(k) = w_l_l(k) + w(k,j,i) &
	282	* MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i), 3 ) )
[76]	283	ENDDO
	284	ENDDO
[1918]	285	ENDDO
[76]	286	#if defined( __parallel )
[1918]	287	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
[4015]	288	CALL MPI_ALLREDUCE( w_l_l(1), w_l(1), nzt, MPI_REAL, MPI_SUM, comm2d, ierr )
[76]	289	#else
[1918]	290	w_l = w_l_l
[76]	291	#endif
[1918]	292	DO k = 1, nzt
	293	w_l(k) = w_l(k) / ngp_2dh_outer(k,0)
	294	ENDDO
	295	DO i = nxlg, nxrg
	296	DO j = nysg, nyng
[2232]	297	DO k = nzb+1, nzt
[4015]	298	w(k,j,i) = w(k,j,i) - w_l(k) &
	299	* MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i), 3 ) )
[76]	300	ENDDO
	301	ENDDO
[1918]	302	ENDDO
[76]	303	ENDIF
[75]	304
	305	!
[1]	306	!-- Compute the divergence of the provisional velocity field.
	307	CALL cpu_log( log_point_s(1), 'divergence', 'start' )
	308
[1575]	309	IF ( psolver(1:9) == 'multigrid' ) THEN
[2232]	310	!$OMP PARALLEL DO SCHEDULE( STATIC ) PRIVATE (i,j,k)
[1]	311	DO i = nxl-1, nxr+1
	312	DO j = nys-1, nyn+1
	313	DO k = nzb, nzt+1
[1342]	314	d(k,j,i) = 0.0_wp
[1]	315	ENDDO
	316	ENDDO
	317	ENDDO
	318	ELSE
[2232]	319	!$OMP PARALLEL DO SCHEDULE( STATIC ) PRIVATE (i,j,k)
[3634]	320	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	321	!$ACC PRESENT(d)
[1003]	322	DO i = nxl, nxr
	323	DO j = nys, nyn
	324	DO k = nzb+1, nzt
[1342]	325	d(k,j,i) = 0.0_wp
[1]	326	ENDDO
	327	ENDDO
	328	ENDDO
	329	ENDIF
	330
[1342]	331	localsum = 0.0_wp
	332	threadsum = 0.0_wp
[1]	333
	334	#if defined( __ibm )
	335	!$OMP PARALLEL PRIVATE (i,j,k) FIRSTPRIVATE(threadsum) REDUCTION(+:localsum)
	336	!$OMP DO SCHEDULE( STATIC )
	337	DO i = nxl, nxr
	338	DO j = nys, nyn
[2232]	339	DO k = nzb+1, nzt
[2037]	340	d(k,j,i) = ( ( u(k,j,i+1) - u(k,j,i) ) * rho_air(k) * ddx + &
	341	( v(k,j+1,i) - v(k,j,i) ) * rho_air(k) * ddy + &
	342	( w(k,j,i) * rho_air_zw(k) - &
	343	w(k-1,j,i) * rho_air_zw(k-1) ) * ddzw(k) &
[2232]	344	) * ddt_3d * d_weight_pres &
	345	* MERGE( 1.0_wp, 0.0_wp, &
	346	BTEST( wall_flags_0(k,j,i), 0 ) &
	347	)
[1]	348	ENDDO
	349	!
	350	!-- Compute possible PE-sum of divergences for flow_statistics
[2232]	351	DO k = nzb+1, nzt
	352	threadsum = threadsum + ABS( d(k,j,i) ) &
	353	* MERGE( 1.0_wp, 0.0_wp, &
	354	BTEST( wall_flags_0(k,j,i), 0 ) &
	355	)
[1]	356	ENDDO
	357
	358	ENDDO
	359	ENDDO
	360
[1918]	361	IF ( intermediate_timestep_count == intermediate_timestep_count_max .OR. &
	362	intermediate_timestep_count == 0 ) THEN
	363	localsum = localsum + threadsum * dt_3d * weight_pres_l
[1908]	364	ENDIF
[1]	365	!$OMP END PARALLEL
	366	#else
	367
[1111]	368	!$OMP PARALLEL PRIVATE (i,j,k)
	369	!$OMP DO SCHEDULE( STATIC )
[3634]	370	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	371	!$ACC PRESENT(u, v, w, rho_air, rho_air_zw, ddzw, wall_flags_0) &
	372	!$ACC PRESENT(d)
[1111]	373	DO i = nxl, nxr
	374	DO j = nys, nyn
	375	DO k = 1, nzt
[2037]	376	d(k,j,i) = ( ( u(k,j,i+1) - u(k,j,i) ) * rho_air(k) * ddx + &
	377	( v(k,j+1,i) - v(k,j,i) ) * rho_air(k) * ddy + &
	378	( w(k,j,i) * rho_air_zw(k) - &
	379	w(k-1,j,i) * rho_air_zw(k-1) ) * ddzw(k) &
[2232]	380	) * ddt_3d * d_weight_pres &
	381	* MERGE( 1.0_wp, 0.0_wp, &
	382	BTEST( wall_flags_0(k,j,i), 0 ) &
	383	)
[1]	384	ENDDO
	385	ENDDO
[1111]	386	ENDDO
	387	!$OMP END PARALLEL
[1]	388
	389	!
[1908]	390	!-- Compute possible PE-sum of divergences for flow_statistics. Carry out
	391	!-- computation only at last Runge-Kutta substep.
[1918]	392	IF ( intermediate_timestep_count == intermediate_timestep_count_max .OR. &
	393	intermediate_timestep_count == 0 ) THEN
[1908]	394	!$OMP PARALLEL PRIVATE (i,j,k) FIRSTPRIVATE(threadsum) REDUCTION(+:localsum)
	395	!$OMP DO SCHEDULE( STATIC )
[3634]	396	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i,j,k) &
	397	!$ACC REDUCTION(+:threadsum) COPY(threadsum) &
	398	!$ACC PRESENT(d)
[1908]	399	DO i = nxl, nxr
	400	DO j = nys, nyn
	401	DO k = nzb+1, nzt
	402	threadsum = threadsum + ABS( d(k,j,i) )
	403	ENDDO
[1]	404	ENDDO
	405	ENDDO
[1918]	406	localsum = localsum + threadsum * dt_3d * weight_pres_l
[1908]	407	!$OMP END PARALLEL
	408	ENDIF
[1]	409	#endif
	410
	411	!
	412	!-- For completeness, set the divergence sum of all statistic regions to those
	413	!-- of the total domain
[1918]	414	IF ( intermediate_timestep_count == intermediate_timestep_count_max .OR. &
	415	intermediate_timestep_count == 0 ) THEN
[1908]	416	sums_divold_l(0:statistic_regions) = localsum
[1918]	417	ENDIF
[1]	418
	419	CALL cpu_log( log_point_s(1), 'divergence', 'stop' )
	420
	421	!
	422	!-- Compute the pressure perturbation solving the Poisson equation
[1575]	423	IF ( psolver == 'poisfft' ) THEN
[1]	424
	425	!
	426	!-- Solve Poisson equation via FFT and solution of tridiagonal matrices
[1575]	427	CALL poisfft( d )
[1212]	428
[1]	429	!
	430	!-- Store computed perturbation pressure and set boundary condition in
	431	!-- z-direction
[2232]	432	!$OMP PARALLEL DO PRIVATE (i,j,k)
[3634]	433	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	434	!$ACC PRESENT(d, tend)
[1]	435	DO i = nxl, nxr
	436	DO j = nys, nyn
	437	DO k = nzb+1, nzt
	438	tend(k,j,i) = d(k,j,i)
	439	ENDDO
	440	ENDDO
	441	ENDDO
	442
	443	!
	444	!-- Bottom boundary:
	445	!-- This condition is only required for internal output. The pressure
	446	!-- gradient (dp(nzb+1)-dp(nzb))/dz is not used anywhere else.
	447	IF ( ibc_p_b == 1 ) THEN
	448	!
[2232]	449	!-- Neumann (dp/dz = 0). Using surfae data type, first for non-natural
	450	!-- surfaces, then for natural and urban surfaces
	451	!-- Upward facing
	452	!$OMP PARALLEL DO PRIVATE( i, j, k )
[3634]	453	!$ACC PARALLEL LOOP PRIVATE(i, j, k) &
	454	!$ACC PRESENT(bc_h, tend)
[2232]	455	DO m = 1, bc_h(0)%ns
[2298]	456	i = bc_h(0)%i(m)
	457	j = bc_h(0)%j(m)
	458	k = bc_h(0)%k(m)
[2232]	459	tend(k-1,j,i) = tend(k,j,i)
[1]	460	ENDDO
[2232]	461	!
	462	!-- Downward facing
	463	!$OMP PARALLEL DO PRIVATE( i, j, k )
[3634]	464	!$ACC PARALLEL LOOP PRIVATE(i, j, k) &
	465	!$ACC PRESENT(bc_h, tend)
[2232]	466	DO m = 1, bc_h(1)%ns
[2298]	467	i = bc_h(1)%i(m)
	468	j = bc_h(1)%j(m)
	469	k = bc_h(1)%k(m)
[2232]	470	tend(k+1,j,i) = tend(k,j,i)
	471	ENDDO
[1]	472
	473	ELSE
	474	!
[2232]	475	!-- Dirichlet. Using surface data type, first for non-natural
	476	!-- surfaces, then for natural and urban surfaces
	477	!-- Upward facing
	478	!$OMP PARALLEL DO PRIVATE( i, j, k )
	479	DO m = 1, bc_h(0)%ns
[2298]	480	i = bc_h(0)%i(m)
	481	j = bc_h(0)%j(m)
	482	k = bc_h(0)%k(m)
[2232]	483	tend(k-1,j,i) = 0.0_wp
[1]	484	ENDDO
[2232]	485	!
	486	!-- Downward facing
	487	!$OMP PARALLEL DO PRIVATE( i, j, k )
	488	DO m = 1, bc_h(1)%ns
[2298]	489	i = bc_h(1)%i(m)
	490	j = bc_h(1)%j(m)
	491	k = bc_h(1)%k(m)
[2232]	492	tend(k+1,j,i) = 0.0_wp
	493	ENDDO
[1]	494
	495	ENDIF
	496
	497	!
	498	!-- Top boundary
	499	IF ( ibc_p_t == 1 ) THEN
	500	!
	501	!-- Neumann
[2232]	502	!$OMP PARALLEL DO PRIVATE (i,j,k)
[667]	503	DO i = nxlg, nxrg
	504	DO j = nysg, nyng
[1]	505	tend(nzt+1,j,i) = tend(nzt,j,i)
	506	ENDDO
	507	ENDDO
	508
	509	ELSE
	510	!
	511	!-- Dirichlet
[2232]	512	!$OMP PARALLEL DO PRIVATE (i,j,k)
[3634]	513	!$ACC PARALLEL LOOP COLLAPSE(2) PRIVATE(i, j) &
	514	!$ACC PRESENT(tend)
[667]	515	DO i = nxlg, nxrg
	516	DO j = nysg, nyng
[1342]	517	tend(nzt+1,j,i) = 0.0_wp
[1]	518	ENDDO
	519	ENDDO
	520
	521	ENDIF
	522
	523	!
	524	!-- Exchange boundaries for p
[667]	525	CALL exchange_horiz( tend, nbgp )
[1]	526
	527	ELSEIF ( psolver == 'sor' ) THEN
	528
	529	!
	530	!-- Solve Poisson equation for perturbation pressure using SOR-Red/Black
	531	!-- scheme
[707]	532	CALL sor( d, ddzu_pres, ddzw, p_loc )
	533	tend = p_loc
[1]	534
[1575]	535	ELSEIF ( psolver(1:9) == 'multigrid' ) THEN
[1]	536
	537	!
	538	!-- Solve Poisson equation for perturbation pressure using Multigrid scheme,
[2298]	539	!-- array tend is used to store the residuals.
[778]	540
	541	!-- If the number of grid points of the gathered grid, which is collected
	542	!-- on PE0, is larger than the number of grid points of an PE, than array
	543	!-- tend will be enlarged.
	544	IF ( gathered_size > subdomain_size ) THEN
	545	DEALLOCATE( tend )
	546	ALLOCATE( tend(nzb:nzt_mg(mg_switch_to_pe0_level)+1,nys_mg( &
	547	mg_switch_to_pe0_level)-1:nyn_mg(mg_switch_to_pe0_level)+1,&
	548	nxl_mg(mg_switch_to_pe0_level)-1:nxr_mg( &
	549	mg_switch_to_pe0_level)+1) )
	550	ENDIF
	551
[1575]	552	IF ( psolver == 'multigrid' ) THEN
	553	CALL poismg( tend )
	554	ELSE
[1931]	555	CALL poismg_noopt( tend )
[1575]	556	ENDIF
[707]	557
[778]	558	IF ( gathered_size > subdomain_size ) THEN
	559	DEALLOCATE( tend )
	560	ALLOCATE( tend(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
	561	ENDIF
	562
[1]	563	!
	564	!-- Restore perturbation pressure on tend because this array is used
	565	!-- further below to correct the velocity fields
[707]	566	DO i = nxl-1, nxr+1
	567	DO j = nys-1, nyn+1
	568	DO k = nzb, nzt+1
	569	tend(k,j,i) = p_loc(k,j,i)
	570	ENDDO
	571	ENDDO
	572	ENDDO
[667]	573
[1]	574	ENDIF
	575
	576	!
[707]	577	!-- Store perturbation pressure on array p, used for pressure data output.
	578	!-- Ghost layers are added in the output routines (except sor-method: see below)
[1918]	579	IF ( intermediate_timestep_count <= 1 ) THEN
[707]	580	!$OMP PARALLEL PRIVATE (i,j,k)
	581	!$OMP DO
[3634]	582	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	583	!$ACC PRESENT(p, tend)
[707]	584	DO i = nxl-1, nxr+1
	585	DO j = nys-1, nyn+1
	586	DO k = nzb, nzt+1
	587	p(k,j,i) = tend(k,j,i) * &
[1929]	588	weight_substep_l
[673]	589	ENDDO
[1]	590	ENDDO
[707]	591	ENDDO
	592	!$OMP END PARALLEL
	593
[1762]	594	ELSEIF ( intermediate_timestep_count > 1 ) THEN
[707]	595	!$OMP PARALLEL PRIVATE (i,j,k)
	596	!$OMP DO
[3634]	597	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	598	!$ACC PRESENT(p, tend)
[707]	599	DO i = nxl-1, nxr+1
	600	DO j = nys-1, nyn+1
	601	DO k = nzb, nzt+1
	602	p(k,j,i) = p(k,j,i) + tend(k,j,i) * &
[1929]	603	weight_substep_l
[673]	604	ENDDO
	605	ENDDO
[707]	606	ENDDO
	607	!$OMP END PARALLEL
	608
	609	ENDIF
[673]	610
[707]	611	!
	612	!-- SOR-method needs ghost layers for the next timestep
	613	IF ( psolver == 'sor' ) CALL exchange_horiz( p, nbgp )
[682]	614
[1]	615	!
	616	!-- Correction of the provisional velocities with the current perturbation
	617	!-- pressure just computed
[709]	618	IF ( conserve_volume_flow .AND. ( bc_lr_cyc .OR. bc_ns_cyc ) ) THEN
[1342]	619	volume_flow_l(1) = 0.0_wp
	620	volume_flow_l(2) = 0.0_wp
[1]	621	ENDIF
[3347]	622	!
	623	!-- Add pressure gradients to the velocity components. Note, the loops are
	624	!-- running over the entire model domain, even though, in case of non-cyclic
	625	!-- boundaries u- and v-component are not prognostic at i=0 and j=0,
	626	!-- respectiveley. However, in case of Dirichlet boundary conditions for the
	627	!-- velocities, zero-gradient conditions for the pressure are set, so that
	628	!-- no modification is imposed at the boundaries.
[1]	629	!$OMP PARALLEL PRIVATE (i,j,k)
	630	!$OMP DO
[3634]	631	!$ACC PARALLEL LOOP COLLAPSE(2) PRIVATE(i, j, k) &
	632	!$ACC PRESENT(u, v, w, tend, ddzu, wall_flags_0)
[673]	633	DO i = nxl, nxr
[1]	634	DO j = nys, nyn
[2118]	635
[2232]	636	DO k = nzb+1, nzt
	637	w(k,j,i) = w(k,j,i) - dt_3d * &
	638	( tend(k+1,j,i) - tend(k,j,i) ) * ddzu(k+1) &
	639	* weight_pres_l &
	640	* MERGE( 1.0_wp, 0.0_wp, &
	641	BTEST( wall_flags_0(k,j,i), 3 ) &
	642	)
[1]	643	ENDDO
[2118]	644
[2232]	645	DO k = nzb+1, nzt
	646	u(k,j,i) = u(k,j,i) - dt_3d * &
	647	( tend(k,j,i) - tend(k,j,i-1) ) * ddx &
	648	* weight_pres_l &
	649	* MERGE( 1.0_wp, 0.0_wp, &
	650	BTEST( wall_flags_0(k,j,i), 1 ) &
	651	)
[1]	652	ENDDO
[2118]	653
[2232]	654	DO k = nzb+1, nzt
	655	v(k,j,i) = v(k,j,i) - dt_3d * &
	656	( tend(k,j,i) - tend(k,j-1,i) ) * ddy &
	657	* weight_pres_l &
	658	* MERGE( 1.0_wp, 0.0_wp, &
	659	BTEST( wall_flags_0(k,j,i), 2 ) &
	660	)
[673]	661	ENDDO
[1]	662
	663	ENDDO
	664	ENDDO
	665	!$OMP END PARALLEL
[1113]	666
	667	!
[3012]	668	!-- The vertical velocity is not set to zero at nzt + 1 for nested domains
	669	!-- Instead it is set to the values of nzt (see routine vnest_boundary_conds
	670	!-- or pmci_interp_tril_t) BEFORE calling the pressure solver. To avoid jumps
	671	!-- while plotting profiles w at the top has to be set to the values in the
	672	!-- height nzt after above modifications. Hint: w level nzt+1 does not impact
	673	!-- results.
[3182]	674	IF ( child_domain .OR. coupling_mode == 'vnested_fine' ) THEN
[3012]	675	w(nzt+1,:,:) = w(nzt,:,:)
	676	ENDIF
	677
	678	!
[1113]	679	!-- Sum up the volume flow through the right and north boundary
[2232]	680	IF ( conserve_volume_flow .AND. bc_lr_cyc .AND. bc_ns_cyc .AND. &
[1113]	681	nxr == nx ) THEN
	682
	683	!$OMP PARALLEL PRIVATE (j,k)
	684	!$OMP DO
	685	DO j = nys, nyn
	686	!$OMP CRITICAL
[2232]	687	DO k = nzb+1, nzt
	688	volume_flow_l(1) = volume_flow_l(1) + u(k,j,nxr) * dzw(k) &
	689	* MERGE( 1.0_wp, 0.0_wp, &
	690	BTEST( wall_flags_0(k,j,nxr), 1 )&
	691	)
[1113]	692	ENDDO
	693	!$OMP END CRITICAL
	694	ENDDO
	695	!$OMP END PARALLEL
	696
	697	ENDIF
	698
[2232]	699	IF ( conserve_volume_flow .AND. bc_ns_cyc .AND. bc_lr_cyc .AND. &
[1113]	700	nyn == ny ) THEN
	701
	702	!$OMP PARALLEL PRIVATE (i,k)
	703	!$OMP DO
	704	DO i = nxl, nxr
	705	!$OMP CRITICAL
[2232]	706	DO k = nzb+1, nzt
	707	volume_flow_l(2) = volume_flow_l(2) + v(k,nyn,i) * dzw(k) &
	708	* MERGE( 1.0_wp, 0.0_wp, &
	709	BTEST( wall_flags_0(k,nyn,i), 2 )&
	710	)
[1113]	711	ENDDO
	712	!$OMP END CRITICAL
	713	ENDDO
	714	!$OMP END PARALLEL
	715
	716	ENDIF
[673]	717
[1]	718	!
	719	!-- Conserve the volume flow
[707]	720	IF ( conserve_volume_flow .AND. ( bc_lr_cyc .AND. bc_ns_cyc ) ) THEN
[1]	721
	722	#if defined( __parallel )
[622]	723	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
[1]	724	CALL MPI_ALLREDUCE( volume_flow_l(1), volume_flow(1), 2, MPI_REAL, &
	725	MPI_SUM, comm2d, ierr )
	726	#else
	727	volume_flow = volume_flow_l
	728	#endif
	729
[1799]	730	volume_flow_offset(1:2) = ( volume_flow_initial(1:2) - volume_flow(1:2) ) / &
	731	volume_flow_area(1:2)
[1]	732
	733	!$OMP PARALLEL PRIVATE (i,j,k)
	734	!$OMP DO
	735	DO i = nxl, nxr
	736	DO j = nys, nyn
[2232]	737	DO k = nzb+1, nzt
	738	u(k,j,i) = u(k,j,i) + volume_flow_offset(1) &
	739	* MERGE( 1.0_wp, 0.0_wp, &
	740	BTEST( wall_flags_0(k,j,i), 1 ) &
	741	)
[719]	742	ENDDO
[2232]	743	DO k = nzb+1, nzt
	744	v(k,j,i) = v(k,j,i) + volume_flow_offset(2) &
	745	* MERGE( 1.0_wp, 0.0_wp, &
	746	BTEST( wall_flags_0(k,j,i), 2 ) &
	747	)
[667]	748	ENDDO
[1]	749	ENDDO
	750	ENDDO
[667]	751
[1]	752	!$OMP END PARALLEL
	753
	754	ENDIF
	755
	756	!
	757	!-- Exchange of boundaries for the velocities
[667]	758	CALL exchange_horiz( u, nbgp )
	759	CALL exchange_horiz( v, nbgp )
	760	CALL exchange_horiz( w, nbgp )
[1]	761
	762	!
	763	!-- Compute the divergence of the corrected velocity field,
[1908]	764	!-- A possible PE-sum is computed in flow_statistics. Carry out computation
	765	!-- only at last Runge-Kutta step.
[1918]	766	IF ( intermediate_timestep_count == intermediate_timestep_count_max .OR. &
	767	intermediate_timestep_count == 0 ) THEN
[1908]	768	CALL cpu_log( log_point_s(1), 'divergence', 'start' )
	769	sums_divnew_l = 0.0_wp
[1]	770
	771	!
[1908]	772	!-- d must be reset to zero because it can contain nonzero values below the
	773	!-- topography
	774	IF ( topography /= 'flat' ) d = 0.0_wp
[1]	775
[1908]	776	localsum = 0.0_wp
	777	threadsum = 0.0_wp
[1]	778
[1908]	779	!$OMP PARALLEL PRIVATE (i,j,k) FIRSTPRIVATE(threadsum) REDUCTION(+:localsum)
[2073]	780	#if defined( __ibm )
[1908]	781	!$OMP DO SCHEDULE( STATIC )
	782	DO i = nxl, nxr
	783	DO j = nys, nyn
[2232]	784	DO k = nzb+1, nzt
	785	d(k,j,i) = ( ( u(k,j,i+1) - u(k,j,i) ) * rho_air(k) * ddx + &
	786	( v(k,j+1,i) - v(k,j,i) ) * rho_air(k) * ddy + &
	787	( w(k,j,i) * rho_air_zw(k) - &
	788	w(k-1,j,i) * rho_air_zw(k-1) ) * ddzw(k) &
	789	) * MERGE( 1.0_wp, 0.0_wp, &
	790	BTEST( wall_flags_0(k,j,i), 0 ) &
	791	)
[1908]	792	ENDDO
	793	DO k = nzb+1, nzt
	794	threadsum = threadsum + ABS( d(k,j,i) )
	795	ENDDO
[1]	796	ENDDO
	797	ENDDO
	798	#else
[2073]	799	!$OMP DO SCHEDULE( STATIC )
[3634]	800	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	801	!$ACC PRESENT(u, v, w, rho_air, rho_air_zw, ddzw, wall_flags_0) &
	802	!$ACC PRESENT(d)
[1908]	803	DO i = nxl, nxr
	804	DO j = nys, nyn
[2232]	805	DO k = nzb+1, nzt
[2037]	806	d(k,j,i) = ( ( u(k,j,i+1) - u(k,j,i) ) * rho_air(k) * ddx + &
	807	( v(k,j+1,i) - v(k,j,i) ) * rho_air(k) * ddy + &
	808	( w(k,j,i) * rho_air_zw(k) - &
	809	w(k-1,j,i) * rho_air_zw(k-1) ) * ddzw(k) &
[2232]	810	) * MERGE( 1.0_wp, 0.0_wp, &
	811	BTEST( wall_flags_0(k,j,i), 0 ) &
	812	)
[1908]	813	ENDDO
[1113]	814	ENDDO
	815	ENDDO
	816	!
[1908]	817	!-- Compute possible PE-sum of divergences for flow_statistics
[2073]	818	!$OMP DO SCHEDULE( STATIC )
[3634]	819	!$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i, j, k) &
	820	!$ACC REDUCTION(+:threadsum) COPY(threadsum) &
	821	!$ACC PRESENT(d)
[1908]	822	DO i = nxl, nxr
	823	DO j = nys, nyn
	824	DO k = nzb+1, nzt
	825	threadsum = threadsum + ABS( d(k,j,i) )
	826	ENDDO
[1]	827	ENDDO
	828	ENDDO
	829	#endif
[667]	830
[1908]	831	localsum = localsum + threadsum
	832	!$OMP END PARALLEL
[1]	833
	834	!
[1908]	835	!-- For completeness, set the divergence sum of all statistic regions to those
	836	!-- of the total domain
	837	sums_divnew_l(0:statistic_regions) = localsum
[1]	838
[1908]	839	CALL cpu_log( log_point_s(1), 'divergence', 'stop' )
[1]	840
[1908]	841	ENDIF
	842
[1]	843	CALL cpu_log( log_point(8), 'pres', 'stop' )
	844
	845	END SUBROUTINE pres

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