source: palm/trunk/SOURCE/lpm_droplet_collision.f90 @ 2699

Last change on this file since 2699 was 2696, checked in by kanani, 7 years ago

Merge of branch palm4u into trunk

  • Property svn:keywords set to Id
File size: 15.1 KB
RevLine 
[1682]1!> @file lpm_droplet_collision.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!
[2101]17! Copyright 1997-2017 Leibniz Universitaet Hannover
[2000]18!------------------------------------------------------------------------------!
[1036]19!
[849]20! Current revisions:
21! ------------------
[2375]22!
23!
[1321]24! Former revisions:
25! -----------------
26! $Id: lpm_droplet_collision.f90 2696 2017-12-14 17:12:51Z kanani $
[2375]27! Changed ONLY-dependencies
28!
29! 2312 2017-07-14 20:26:51Z hoffmann
[2312]30! Consideration of aerosol mass during collision. Average impact algorithm has
31! been removed.
32!
33! 2274 2017-06-09 13:27:48Z Giersch
[2274]34! Changed error messages
[1321]35!
[2274]36! 2123 2017-01-18 12:34:59Z hoffmann
37!
[2123]38! 2122 2017-01-18 12:22:54Z hoffmann
39! Some reformatting of the code.
40!
[2001]41! 2000 2016-08-20 18:09:15Z knoop
42! Forced header and separation lines into 80 columns
43!
[1885]44! 1884 2016-04-21 11:11:40Z hoffmann
45! Conservation of mass should only be checked if collisions took place.
46!
[1861]47! 1860 2016-04-13 13:21:28Z hoffmann
[2312]48! Interpolation of dissipation rate adjusted to more reasonable values.
[1861]49!
[1823]50! 1822 2016-04-07 07:49:42Z hoffmann
51! Integration of a new collision algortithm based on Shima et al. (2009) and
52! Soelch and Kaercher (2010) called all_or_nothing. The previous implemented
53! collision algorithm is called average_impact. Moreover, both algorithms are
54! now positive definit due to their construction, i.e., no negative weighting
55! factors should occur.
56!
[1683]57! 1682 2015-10-07 23:56:08Z knoop
[2312]58! Code annotations made doxygen readable
59!
[1360]60! 1359 2014-04-11 17:15:14Z hoffmann
[2312]61! New particle structure integrated.
[1360]62! Kind definition added to all floating point numbers.
63!
[1323]64! 1322 2014-03-20 16:38:49Z raasch
65! REAL constants defined as wp_kind
66!
[1321]67! 1320 2014-03-20 08:40:49Z raasch
[1320]68! ONLY-attribute added to USE-statements,
69! kind-parameters added to all INTEGER and REAL declaration statements,
70! kinds are defined in new module kinds,
71! revision history before 2012 removed,
72! comment fields (!:) to be used for variable explanations added to
73! all variable declaration statements
[1072]74!
[1093]75! 1092 2013-02-02 11:24:22Z raasch
76! unused variables removed
77!
[1072]78! 1071 2012-11-29 16:54:55Z franke
[1071]79! Calculation of Hall and Wang kernel now uses collision-coalescence formulation
80! proposed by Wang instead of the continuous collection equation (for more
81! information about new method see PALM documentation)
82! Bugfix: message identifiers added
[849]83!
[1037]84! 1036 2012-10-22 13:43:42Z raasch
85! code put under GPL (PALM 3.9)
86!
[850]87! 849 2012-03-15 10:35:09Z raasch
88! initial revision (former part of advec_particles)
[849]89!
[850]90!
[849]91! Description:
92! ------------
[1682]93!> Calculates change in droplet radius by collision. Droplet collision is
94!> calculated for each grid box seperately. Collision is parameterized by
[1822]95!> using collision kernels. Two different kernels are available:
[1682]96!> Hall kernel: Kernel from Hall (1980, J. Atmos. Sci., 2486-2507), which
97!>              considers collision due to pure gravitational effects.
98!> Wang kernel: Beside gravitational effects (treated with the Hall-kernel) also
99!>              the effects of turbulence on the collision are considered using
100!>              parameterizations of Ayala et al. (2008, New J. Phys., 10,
101!>              075015) and Wang and Grabowski (2009, Atmos. Sci. Lett., 10,
102!>              1-8). This kernel includes three possible effects of turbulence:
103!>              the modification of the relative velocity between the droplets,
104!>              the effect of preferential concentration, and the enhancement of
[2312]105!>              collision efficiencies.
[849]106!------------------------------------------------------------------------------!
[1682]107 SUBROUTINE lpm_droplet_collision (i,j,k)
[849]108
[1320]109    USE arrays_3d,                                                             &
[1822]110        ONLY:  diss, ql_v, ql_vp
[849]111
[1320]112    USE cloud_parameters,                                                      &
[2375]113        ONLY:  rho_l, rho_s
[1320]114
115    USE constants,                                                             &
116        ONLY:  pi
117
118    USE control_parameters,                                                    &
[1822]119        ONLY:  dt_3d, message_string, dz
[1320]120
121    USE cpulog,                                                                &
122        ONLY:  cpu_log, log_point_s
123
124    USE grid_variables,                                                        &
[1822]125        ONLY:  dx, dy
[1320]126
127    USE kinds
128
129    USE lpm_collision_kernels_mod,                                             &
[1822]130        ONLY:  ckernel, recalculate_kernel
[1320]131
132    USE particle_attributes,                                                   &
[2312]133        ONLY:  curvature_solution_effects, dissipation_classes, hall_kernel,   &
134               iran_part, number_of_particles, particles, particle_type,       &
[2375]135               prt_count, use_kernel_tables, wang_kernel
[1320]136
[1822]137    USE random_function_mod,                                                   &
138        ONLY:  random_function
139
[1359]140    USE pegrid
141
[849]142    IMPLICIT NONE
143
[1682]144    INTEGER(iwp) ::  eclass   !<
145    INTEGER(iwp) ::  i        !<
146    INTEGER(iwp) ::  j        !<
147    INTEGER(iwp) ::  k        !<
148    INTEGER(iwp) ::  n        !<
[1822]149    INTEGER(iwp) ::  m        !<
[1682]150    INTEGER(iwp) ::  rclass_l !<
151    INTEGER(iwp) ::  rclass_s !<
[849]152
[1822]153    REAL(wp) ::  collection_probability  !< probability for collection
154    REAL(wp) ::  ddV                     !< inverse grid box volume
155    REAL(wp) ::  epsilon                 !< dissipation rate
156    REAL(wp) ::  factor_volume_to_mass   !< 4.0 / 3.0 * pi * rho_l
[2312]157    REAL(wp) ::  xm                      !< droplet mass of super-droplet m
158    REAL(wp) ::  xn                      !< droplet mass of super-droplet n
159    REAL(wp) ::  xsm                     !< aerosol mass of super-droplet m
160    REAL(wp) ::  xsn                     !< aerosol mass of super-droplet n
[1359]161
[2312]162    REAL(wp), DIMENSION(:), ALLOCATABLE ::  weight    !< weighting factor
163    REAL(wp), DIMENSION(:), ALLOCATABLE ::  mass      !< total mass of super droplet
164    REAL(wp), DIMENSION(:), ALLOCATABLE ::  aero_mass !< total aerosol mass of super droplet
[1359]165
[849]166    CALL cpu_log( log_point_s(43), 'lpm_droplet_coll', 'start' )
167
[1822]168    number_of_particles   = prt_count(k,j,i)
[2312]169    factor_volume_to_mass = 4.0_wp / 3.0_wp * pi * rho_l
170    ddV                   = 1.0_wp / ( dx * dy * dz )
[849]171!
[1822]172!-- Collision requires at least one super droplet inside the box
173    IF ( number_of_particles > 0 )  THEN
[849]174
[1822]175       IF ( use_kernel_tables )  THEN
[849]176!
[1822]177!--       Fast method with pre-calculated collection kernels for
[1359]178!--       discrete radius- and dissipation-classes.
179          IF ( wang_kernel )  THEN
[1860]180             eclass = INT( diss(k,j,i) * 1.0E4_wp / 600.0_wp * &
[1359]181                           dissipation_classes ) + 1
182             epsilon = diss(k,j,i)
183          ELSE
184             epsilon = 0.0_wp
185          ENDIF
[2312]186
[1359]187          IF ( hall_kernel  .OR.  epsilon * 1.0E4_wp < 0.001_wp )  THEN
188             eclass = 0   ! Hall kernel is used
189          ELSE
190             eclass = MIN( dissipation_classes, eclass )
191          ENDIF
192
[2312]193       ELSE
[849]194!
[2312]195!--       Collection kernels are re-calculated for every new
[1822]196!--       grid box. First, allocate memory for kernel table.
197!--       Third dimension is 1, because table is re-calculated for
198!--       every new dissipation value.
199          ALLOCATE( ckernel(1:number_of_particles,1:number_of_particles,1:1) )
200!
201!--       Now calculate collection kernel for this box. Note that
202!--       the kernel is based on the previous time step
203          CALL recalculate_kernel( i, j, k )
[2312]204
205       ENDIF
[1822]206!
[2312]207!--    Temporary fields for total mass of super-droplet, aerosol mass, and
208!--    weighting factor are allocated.
209       ALLOCATE(mass(1:number_of_particles), weight(1:number_of_particles))
210       IF ( curvature_solution_effects )  ALLOCATE(aero_mass(1:number_of_particles))
[849]211
[2312]212       mass(1:number_of_particles)   = particles(1:number_of_particles)%weight_factor * &
213                                       particles(1:number_of_particles)%radius**3     * &
214                                       factor_volume_to_mass
[849]215
[2312]216       weight(1:number_of_particles) = particles(1:number_of_particles)%weight_factor
[849]217
[2312]218       IF ( curvature_solution_effects )  THEN
219          aero_mass(1:number_of_particles) = particles(1:number_of_particles)%weight_factor * &
220                                             particles(1:number_of_particles)%aux1**3       * &
221                                             4.0 / 3.0 * pi * rho_s
222       ENDIF
223!
224!--    Calculate collision/coalescence
225       DO  n = 1, number_of_particles
[849]226
[2312]227          DO  m = n, number_of_particles
228!
229!--          For collisions, the weighting factor of at least one super-droplet
230!--          needs to be larger or equal to one.
231             IF ( MIN( weight(n), weight(m) ) .LT. 1.0 )  CYCLE
232!
233!--          Get mass of individual droplets (aerosols)
234             xn = mass(n) / weight(n)
235             xm = mass(m) / weight(m)
236             IF ( curvature_solution_effects )  THEN
237                xsn = aero_mass(n) / weight(n)
238                xsm = aero_mass(m) / weight(m)
239             ENDIF
240!
241!--          Probability that the necessary collisions take place
242             IF ( use_kernel_tables )  THEN
243                rclass_l = particles(n)%class
244                rclass_s = particles(m)%class
[849]245
[2312]246                collection_probability  = MAX( weight(n), weight(m) ) *     &
247                                          ckernel(rclass_l,rclass_s,eclass) * ddV * dt_3d
248             ELSE
249                collection_probability  = MAX( weight(n), weight(m) ) *     &
250                                          ckernel(n,m,1) * ddV * dt_3d
251             ENDIF
[849]252!
[2312]253!--          Calculate the number of collections and consider multiple collections.
254!--          (Accordingly, p_crit will be 0.0, 1.0, 2.0, ...)
255             IF ( collection_probability - FLOOR(collection_probability)    &
256                  .GT. random_function( iran_part ) )  THEN
257                collection_probability = FLOOR(collection_probability) + 1.0_wp
258             ELSE
259                collection_probability = FLOOR(collection_probability)
260             ENDIF
[1822]261
[2312]262             IF ( collection_probability .GT. 0.0 )  THEN
[849]263!
[2312]264!--             Super-droplet n collects droplets of super-droplet m
265                IF ( weight(n) .LT. weight(m) )  THEN
[849]266
[2312]267                   mass(n)   = mass(n)   + weight(n) * xm * collection_probability
268                   weight(m) = weight(m) - weight(n)      * collection_probability
269                   mass(m)   = mass(m)   - weight(n) * xm * collection_probability
270                   IF ( curvature_solution_effects )  THEN
271                      aero_mass(n) = aero_mass(n) + weight(n) * xsm * collection_probability
272                      aero_mass(m) = aero_mass(m) - weight(n) * xsm * collection_probability
[1822]273                   ENDIF
[849]274
[2312]275                ELSEIF ( weight(m) .LT. weight(n) )  THEN
[849]276
[2312]277                   mass(m)   = mass(m)   + weight(m) * xn * collection_probability
278                   weight(n) = weight(n) - weight(m)      * collection_probability
279                   mass(n)   = mass(n)   - weight(m) * xn * collection_probability
280                   IF ( curvature_solution_effects )  THEN
281                      aero_mass(m) = aero_mass(m) + weight(m) * xsn * collection_probability
282                      aero_mass(n) = aero_mass(n) - weight(m) * xsn * collection_probability
283                   ENDIF
[849]284
[2312]285                ELSE
[1822]286!
[2312]287!--                Collisions of particles of the same weighting factor.
288!--                Particle n collects 1/2 weight(n) droplets of particle m,
289!--                particle m collects 1/2 weight(m) droplets of particle n.
290!--                The total mass mass changes accordingly.
291!--                If n = m, the first half of the droplets coalesces with the
292!--                second half of the droplets; mass is unchanged because
293!--                xm = xn for n = m.
[1822]294!--
[2312]295!--                Note: For m = n this equation is an approximation only
296!--                valid for weight >> 1 (which is usually the case). The
297!--                approximation is weight(n)-1 = weight(n).
298                   mass(n)   = mass(n)   + 0.5_wp * weight(n) * ( xm - xn )
299                   mass(m)   = mass(m)   + 0.5_wp * weight(m) * ( xn - xm )
300                   IF ( curvature_solution_effects )  THEN
301                      aero_mass(n) = aero_mass(n) + 0.5_wp * weight(n) * ( xsm - xsn )
302                      aero_mass(m) = aero_mass(m) + 0.5_wp * weight(m) * ( xsn - xsm )
[1822]303                   ENDIF
[2312]304                   weight(n) = weight(n) - 0.5_wp * weight(m)
305                   weight(m) = weight(n)
[1071]306
[2312]307                ENDIF
[1071]308
[2312]309             ENDIF
[1071]310
[2312]311          ENDDO
[1071]312
[2312]313          ql_vp(k,j,i) = ql_vp(k,j,i) + mass(n) / factor_volume_to_mass
[1071]314
[2312]315       ENDDO
[1071]316
[2312]317       IF ( ANY(weight < 0.0_wp) )  THEN
318             WRITE( message_string, * ) 'negative weighting factor'
319             CALL message( 'lpm_droplet_collision', 'PA0028',      &
320                            2, 2, -1, 6, 1 )
321       ENDIF
[1822]322
[2312]323       particles(1:number_of_particles)%radius = ( mass(1:number_of_particles) /   &
324                                                   ( weight(1:number_of_particles) &
325                                                     * factor_volume_to_mass       &
326                                                   )                               &
327                                                 )**0.33333333333333_wp
[1822]328
[2312]329       IF ( curvature_solution_effects )  THEN
330          particles(1:number_of_particles)%aux1 = ( aero_mass(1:number_of_particles) / &
331                                                    ( weight(1:number_of_particles)    &
332                                                      * 4.0_wp / 3.0_wp * pi * rho_s   &
333                                                    )                                  &
334                                                  )**0.33333333333333_wp
335       ENDIF
[1822]336
[2312]337       particles(1:number_of_particles)%weight_factor = weight(1:number_of_particles)
[1822]338
[2312]339       DEALLOCATE( weight, mass )
340       IF ( curvature_solution_effects )  DEALLOCATE( aero_mass )
341       IF ( .NOT. use_kernel_tables )  DEALLOCATE( ckernel )
342
[849]343!
[1884]344!--    Check if LWC is conserved during collision process
345       IF ( ql_v(k,j,i) /= 0.0_wp )  THEN
346          IF ( ql_vp(k,j,i) / ql_v(k,j,i) >= 1.0001_wp  .OR.                      &
347               ql_vp(k,j,i) / ql_v(k,j,i) <= 0.9999_wp )  THEN
348             WRITE( message_string, * ) ' LWC is not conserved during',           &
349                                        ' collision! ',                           &
350                                        ' LWC after condensation: ', ql_v(k,j,i), &
351                                        ' LWC after collision: ', ql_vp(k,j,i)
352             CALL message( 'lpm_droplet_collision', 'PA0040', 2, 2, -1, 6, 1 )
353          ENDIF
[1359]354       ENDIF
[1884]355
[1359]356    ENDIF
[2312]357
[849]358    CALL cpu_log( log_point_s(43), 'lpm_droplet_coll', 'stop' )
359
[2312]360 END SUBROUTINE lpm_droplet_collision
Note: See TracBrowser for help on using the repository browser.