source: palm/trunk/SOURCE/diffusivities.f90 @ 1323

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1 SUBROUTINE diffusivities( var, var_reference )
2
3!--------------------------------------------------------------------------------!
4! This file is part of PALM.
5!
6! PALM is free software: you can redistribute it and/or modify it under the terms
7! of the GNU General Public License as published by the Free Software Foundation,
8! either version 3 of the License, or (at your option) any later version.
9!
10! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
11! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
12! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
13!
14! You should have received a copy of the GNU General Public License along with
15! PALM. If not, see <http://www.gnu.org/licenses/>.
16!
17! Copyright 1997-2014 Leibniz Universitaet Hannover
18!--------------------------------------------------------------------------------!
19!
20! Current revisions:
21! -----------------
22!
23!
24! Former revisions:
25! -----------------
26! $Id: diffusivities.f90 1323 2014-03-20 17:09:54Z raasch $
27!
28! 1322 2014-03-20 16:38:49Z raasch
29! REAL constants defined as wp-kind
30!
31! 1320 2014-03-20 08:40:49Z raasch
32! ONLY-attribute added to USE-statements,
33! kind-parameters added to all INTEGER and REAL declaration statements,
34! kinds are defined in new module kinds,
35! revision history before 2012 removed,
36! comment fields (!:) to be used for variable explanations added to
37! all variable declaration statements
38!
39! 1179 2013-06-14 05:57:58Z raasch
40! use_reference renamed use_single_reference_value
41!
42! 1036 2012-10-22 13:43:42Z raasch
43! code put under GPL (PALM 3.9)
44!
45! 1015 2012-09-27 09:23:24Z raasch
46! OpenACC statements added + code changes required for GPU optimization,
47! adjustment of mixing length to the Prandtl mixing length at first grid point
48! above ground removed
49!
50! Revision 1.1  1997/09/19 07:41:10  raasch
51! Initial revision
52!
53!
54! Description:
55! ------------
56! Computation of the turbulent diffusion coefficients for momentum and heat
57! according to Prandtl-Kolmogorov
58!------------------------------------------------------------------------------!
59
60    USE arrays_3d,                                                             &
61        ONLY:  dd2zu, e, kh, km, l_grid, l_wall
62       
63    USE control_parameters,                                                    &
64        ONLY:  atmos_ocean_sign, e_min, g, outflow_l, outflow_n, outflow_r,    &
65                outflow_s, use_single_reference_value, wall_adjustment
66               
67    USE indices,                                                               &
68        ONLY:  nxl, nxlg, nxr, nxrg, nyn, nyng, nys, nysg, nzb_s_inner, nzb, nzt
69    USE kinds
70   
71    USE pegrid
72   
73    USE statistics,                                                            &
74        ONLY :  rmask, statistic_regions, sums_l_l
75
76    IMPLICIT NONE
77
78    INTEGER(iwp) ::  i                   !:
79    INTEGER(iwp) ::  j                   !:
80    INTEGER(iwp) ::  k                   !:
81    INTEGER(iwp) ::  omp_get_thread_num  !:
82    INTEGER(iwp) ::  sr                  !:
83    INTEGER(iwp) ::  tn                  !:
84
85    REAL(wp)     ::  dvar_dz             !:
86    REAL(wp)     ::  l                   !:
87    REAL(wp)     ::  ll                  !:
88    REAL(wp)     ::  l_stable            !:
89    REAL(wp)     ::  sqrt_e              !:
90    REAL(wp)     ::  var_reference       !:
91
92    REAL(wp)     ::  var(nzb:nzt+1,nysg:nyng,nxlg:nxrg)  !:
93
94
95!
96!-- Default thread number in case of one thread
97    tn = 0
98
99!
100!-- Initialization for calculation of the mixing length profile
101    sums_l_l = 0.0
102
103!
104!-- Compute the turbulent diffusion coefficient for momentum
105    !$OMP PARALLEL PRIVATE (dvar_dz,i,j,k,l,ll,l_stable,sqrt_e,sr,tn)
106!$  tn = omp_get_thread_num()
107
108!
109!-- Data declerations for accelerators
110    !$acc data present( dd2zu, e, km, kh, l_grid, l_wall, nzb_s_inner, rif, var )
111    !$acc kernels
112
113!
114!-- Introduce an optional minimum tke
115    IF ( e_min > 0.0 )  THEN
116       !$OMP DO
117       !$acc loop
118       DO  i = nxlg, nxrg
119          DO  j = nysg, nyng
120             !$acc loop vector( 32 )
121             DO  k = 1, nzt
122                IF ( k > nzb_s_inner(j,i) )  THEN
123                   e(k,j,i) = MAX( e(k,j,i), e_min )
124                ENDIF
125             ENDDO
126          ENDDO
127       ENDDO
128    ENDIF
129
130    !$OMP DO
131    !$acc loop
132    DO  i = nxlg, nxrg
133       DO  j = nysg, nyng
134          !$acc loop vector( 32 )
135          DO  k = 1, nzt
136
137             IF ( k > nzb_s_inner(j,i) )  THEN
138
139                sqrt_e = SQRT( e(k,j,i) )
140!
141!--             Determine the mixing length
142                dvar_dz = atmos_ocean_sign * &  ! inverse effect of pt/rho gradient
143                          ( var(k+1,j,i) - var(k-1,j,i) ) * dd2zu(k)
144                IF ( dvar_dz > 0.0 ) THEN
145                   IF ( use_single_reference_value )  THEN
146                      l_stable = 0.76_wp * sqrt_e /                            &
147                                 SQRT( g / var_reference * dvar_dz ) + 1E-5_wp
148                   ELSE
149                      l_stable = 0.76_wp * sqrt_e /                            &
150                                 SQRT( g / var(k,j,i) * dvar_dz ) + 1E-5_wp
151                   ENDIF
152                ELSE
153                   l_stable = l_grid(k)
154                ENDIF
155!
156!--             Adjustment of the mixing length
157                IF ( wall_adjustment )  THEN
158                   = MIN( l_wall(k,j,i), l_grid(k), l_stable )
159                   ll = MIN( l_wall(k,j,i), l_grid(k) )
160                ELSE
161                   = MIN( l_grid(k), l_stable )
162                   ll = l_grid(k)
163                ENDIF
164
165      !
166      !--       Compute diffusion coefficients for momentum and heat
167                km(k,j,i) = 0.1_wp * l * sqrt_e
168                kh(k,j,i) = ( 1.0_wp + 2.0_wp * l / ll ) * km(k,j,i)
169
170             ENDIF
171
172#if ! defined( __openacc )
173!
174!++          Statistics still have to be realized for accelerators
175!--          Summation for averaged profile (cf. flow_statistics)
176             DO  sr = 0, statistic_regions
177                sums_l_l(k,sr,tn) = sums_l_l(k,sr,tn) + l * rmask(j,i,sr)
178             ENDDO
179#endif
180
181          ENDDO
182       ENDDO
183    ENDDO
184
185#if ! defined( __openacc )
186!
187!++ Statistics still have to be realized for accelerators
188    sums_l_l(nzt+1,:,tn) = sums_l_l(nzt,:,tn)   ! quasi boundary-condition for
189                                                  ! data output
190#endif
191    !$OMP END PARALLEL
192
193!
194!-- Set vertical boundary values (Neumann conditions both at bottom and top).
195!-- Horizontal boundary conditions at vertical walls are not set because
196!-- so far vertical walls require usage of a Prandtl-layer where the boundary
197!-- values of the diffusivities are not needed
198    !$OMP PARALLEL DO
199    !$acc loop
200    DO  i = nxlg, nxrg
201       DO  j = nysg, nyng
202          km(nzb_s_inner(j,i),j,i) = km(nzb_s_inner(j,i)+1,j,i)
203          km(nzt+1,j,i)            = km(nzt,j,i)
204          kh(nzb_s_inner(j,i),j,i) = kh(nzb_s_inner(j,i)+1,j,i)
205          kh(nzt+1,j,i)            = kh(nzt,j,i)
206       ENDDO
207    ENDDO
208
209!
210!-- Set Neumann boundary conditions at the outflow boundaries in case of
211!-- non-cyclic lateral boundaries
212    IF ( outflow_l )  THEN
213       km(:,:,nxl-1) = km(:,:,nxl)
214       kh(:,:,nxl-1) = kh(:,:,nxl)
215    ENDIF
216    IF ( outflow_r )  THEN
217       km(:,:,nxr+1) = km(:,:,nxr)
218       kh(:,:,nxr+1) = kh(:,:,nxr)
219    ENDIF
220    IF ( outflow_s )  THEN
221       km(:,nys-1,:) = km(:,nys,:)
222       kh(:,nys-1,:) = kh(:,nys,:)
223    ENDIF
224    IF ( outflow_n )  THEN
225       km(:,nyn+1,:) = km(:,nyn,:)
226       kh(:,nyn+1,:) = kh(:,nyn,:)
227    ENDIF
228
229    !$acc end kernels
230    !$acc end data
231
232 END SUBROUTINE diffusivities
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