source: palm/trunk/SOURCE/diffusivities.f90 @ 2119

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1!> @file diffusivities.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: diffusivities.f90 2119 2017-01-17 16:51:50Z raasch $
27!
28! 2118 2017-01-17 16:38:49Z raasch
29! OpenACC directives removed
30!
31! 2031 2016-10-21 15:11:58Z knoop
32! renamed variable rho to rho_ocean
33!
34! 2000 2016-08-20 18:09:15Z knoop
35! Forced header and separation lines into 80 columns
36!
37! 1711 2015-11-05 07:38:04Z raasch
38! bugfix: loop moved into IF block to avoid usage of l without being defined
39!
40! 1682 2015-10-07 23:56:08Z knoop
41! Code annotations made doxygen readable
42!
43! 1374 2014-04-25 12:55:07Z raasch
44! rif removed from acc-present-list
45!
46! 1353 2014-04-08 15:21:23Z heinze
47! REAL constants provided with KIND-attribute
48!
49! 1340 2014-03-25 19:45:13Z kanani
50! REAL constants defined as wp-kind
51!
52! 1322 2014-03-20 16:38:49Z raasch
53! REAL constants defined as wp-kind
54!
55! 1320 2014-03-20 08:40:49Z raasch
56! ONLY-attribute added to USE-statements,
57! kind-parameters added to all INTEGER and REAL declaration statements,
58! kinds are defined in new module kinds,
59! revision history before 2012 removed,
60! comment fields (!:) to be used for variable explanations added to
61! all variable declaration statements
62!
63! 1179 2013-06-14 05:57:58Z raasch
64! use_reference renamed use_single_reference_value
65!
66! 1036 2012-10-22 13:43:42Z raasch
67! code put under GPL (PALM 3.9)
68!
69! 1015 2012-09-27 09:23:24Z raasch
70! OpenACC statements added + code changes required for GPU optimization,
71! adjustment of mixing length to the Prandtl mixing length at first grid point
72! above ground removed
73!
74! Revision 1.1  1997/09/19 07:41:10  raasch
75! Initial revision
76!
77!
78! Description:
79! ------------
80!> Computation of the turbulent diffusion coefficients for momentum and heat
81!> according to Prandtl-Kolmogorov
82!------------------------------------------------------------------------------!
83 SUBROUTINE diffusivities( var, var_reference )
84 
85
86    USE arrays_3d,                                                             &
87        ONLY:  dd2zu, e, kh, km, l_grid, l_wall
88       
89    USE control_parameters,                                                    &
90        ONLY:  atmos_ocean_sign, e_min, g, outflow_l, outflow_n, outflow_r,    &
91                outflow_s, use_single_reference_value, wall_adjustment
92               
93    USE indices,                                                               &
94        ONLY:  nxl, nxlg, nxr, nxrg, nyn, nyng, nys, nysg, nzb_s_inner, nzb, nzt
95    USE kinds
96   
97    USE pegrid
98   
99    USE statistics,                                                            &
100        ONLY :  rmask, statistic_regions, sums_l_l
101
102    IMPLICIT NONE
103
104    INTEGER(iwp) ::  i                   !<
105    INTEGER(iwp) ::  j                   !<
106    INTEGER(iwp) ::  k                   !<
107    INTEGER(iwp) ::  omp_get_thread_num  !<
108    INTEGER(iwp) ::  sr                  !<
109    INTEGER(iwp) ::  tn                  !<
110
111    REAL(wp)     ::  dvar_dz             !<
112    REAL(wp)     ::  l                   !<
113    REAL(wp)     ::  ll                  !<
114    REAL(wp)     ::  l_stable            !<
115    REAL(wp)     ::  sqrt_e              !<
116    REAL(wp)     ::  var_reference       !<
117
118    REAL(wp)     ::  var(nzb:nzt+1,nysg:nyng,nxlg:nxrg)  !<
119
120
121!
122!-- Default thread number in case of one thread
123    tn = 0
124
125!
126!-- Initialization for calculation of the mixing length profile
127    sums_l_l = 0.0_wp
128
129!
130!-- Compute the turbulent diffusion coefficient for momentum
131    !$OMP PARALLEL PRIVATE (dvar_dz,i,j,k,l,ll,l_stable,sqrt_e,sr,tn)
132!$  tn = omp_get_thread_num()
133
134!
135!-- Introduce an optional minimum tke
136    IF ( e_min > 0.0_wp )  THEN
137       !$OMP DO
138       DO  i = nxlg, nxrg
139          DO  j = nysg, nyng
140             DO  k = 1, nzt
141                IF ( k > nzb_s_inner(j,i) )  THEN
142                   e(k,j,i) = MAX( e(k,j,i), e_min )
143                ENDIF
144             ENDDO
145          ENDDO
146       ENDDO
147    ENDIF
148
149    !$OMP DO
150    DO  i = nxlg, nxrg
151       DO  j = nysg, nyng
152          DO  k = 1, nzt
153
154             IF ( k > nzb_s_inner(j,i) )  THEN
155
156                sqrt_e = SQRT( e(k,j,i) )
157!
158!--             Determine the mixing length
159                dvar_dz = atmos_ocean_sign * &  ! inverse effect of pt/rho_ocean gradient
160                          ( var(k+1,j,i) - var(k-1,j,i) ) * dd2zu(k)
161                IF ( dvar_dz > 0.0_wp ) THEN
162                   IF ( use_single_reference_value )  THEN
163                      l_stable = 0.76_wp * sqrt_e /                            &
164                                    SQRT( g / var_reference * dvar_dz ) + 1E-5_wp
165                   ELSE
166                      l_stable = 0.76_wp * sqrt_e /                            &
167                                    SQRT( g / var(k,j,i) * dvar_dz ) + 1E-5_wp
168                   ENDIF
169                ELSE
170                   l_stable = l_grid(k)
171                ENDIF
172!
173!--             Adjustment of the mixing length
174                IF ( wall_adjustment )  THEN
175                   = MIN( l_wall(k,j,i), l_grid(k), l_stable )
176                   ll = MIN( l_wall(k,j,i), l_grid(k) )
177                ELSE
178                   = MIN( l_grid(k), l_stable )
179                   ll = l_grid(k)
180                ENDIF
181
182      !
183      !--       Compute diffusion coefficients for momentum and heat
184                km(k,j,i) = 0.1_wp * l * sqrt_e
185                kh(k,j,i) = ( 1.0_wp + 2.0_wp * l / ll ) * km(k,j,i)
186
187!
188!--             Summation for averaged profile (cf. flow_statistics)
189                DO  sr = 0, statistic_regions
190                   sums_l_l(k,sr,tn) = sums_l_l(k,sr,tn) + l * rmask(j,i,sr)
191                ENDDO
192
193             ENDIF
194
195          ENDDO
196       ENDDO
197    ENDDO
198
199    sums_l_l(nzt+1,:,tn) = sums_l_l(nzt,:,tn)   ! quasi boundary-condition for
200                                                ! data output
201!$OMP END PARALLEL
202
203!
204!-- Set vertical boundary values (Neumann conditions both at bottom and top).
205!-- Horizontal boundary conditions at vertical walls are not set because
206!-- so far vertical walls require usage of a Prandtl-layer where the boundary
207!-- values of the diffusivities are not needed
208    !$OMP PARALLEL DO
209    DO  i = nxlg, nxrg
210       DO  j = nysg, nyng
211          km(nzb_s_inner(j,i),j,i) = km(nzb_s_inner(j,i)+1,j,i)
212          km(nzt+1,j,i)            = km(nzt,j,i)
213          kh(nzb_s_inner(j,i),j,i) = kh(nzb_s_inner(j,i)+1,j,i)
214          kh(nzt+1,j,i)            = kh(nzt,j,i)
215       ENDDO
216    ENDDO
217
218!
219!-- Set Neumann boundary conditions at the outflow boundaries in case of
220!-- non-cyclic lateral boundaries
221    IF ( outflow_l )  THEN
222       km(:,:,nxl-1) = km(:,:,nxl)
223       kh(:,:,nxl-1) = kh(:,:,nxl)
224    ENDIF
225    IF ( outflow_r )  THEN
226       km(:,:,nxr+1) = km(:,:,nxr)
227       kh(:,:,nxr+1) = kh(:,:,nxr)
228    ENDIF
229    IF ( outflow_s )  THEN
230       km(:,nys-1,:) = km(:,nys,:)
231       kh(:,nys-1,:) = kh(:,nys,:)
232    ENDIF
233    IF ( outflow_n )  THEN
234       km(:,nyn+1,:) = km(:,nyn,:)
235       kh(:,nyn+1,:) = kh(:,nyn,:)
236    ENDIF
237
238 END SUBROUTINE diffusivities
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