[2263] | 1 | !> @file lpm_merging.f90 |
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| 2 | !------------------------------------------------------------------------------! |
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[2696] | 3 | ! This file is part of the PALM model system. |
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[2263] | 4 | ! |
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| 5 | ! PALM is free software: you can redistribute it and/or modify it under the |
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| 6 | ! terms of the GNU General Public License as published by the Free Software |
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| 7 | ! Foundation, either version 3 of the License, or (at your option) any later |
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| 8 | ! version. |
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| 9 | ! |
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| 10 | ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY |
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| 11 | ! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR |
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| 12 | ! A PARTICULAR PURPOSE. See the GNU General Public License for more details. |
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| 13 | ! |
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| 14 | ! You should have received a copy of the GNU General Public License along with |
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| 15 | ! PALM. If not, see <http://www.gnu.org/licenses/>. |
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| 16 | ! |
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[3655] | 17 | ! Copyright 1997-2019 Leibniz Universitaet Hannover |
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[2263] | 18 | !------------------------------------------------------------------------------! |
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| 19 | ! |
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| 20 | ! Current revisions: |
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| 21 | ! ------------------ |
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| 22 | ! |
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| 23 | ! |
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| 24 | ! Former revisions: |
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| 25 | ! ----------------- |
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[2716] | 26 | ! $Id: lpm_merging.f90 3655 2019-01-07 16:51:22Z knoop $ |
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[3241] | 27 | ! unused variables removed |
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| 28 | ! |
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| 29 | ! 2718 2018-01-02 08:49:38Z maronga |
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[2716] | 30 | ! Corrected "Former revisions" section |
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| 31 | ! Change in file header (GPL part) |
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[2278] | 32 | ! Added comments |
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[2263] | 33 | ! |
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[2278] | 34 | ! 2263 2017-06-08 14:59:01Z schwenkel |
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| 35 | ! Initial revision |
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| 36 | ! |
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[2263] | 37 | ! |
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| 38 | ! Description: |
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| 39 | ! ------------ |
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| 40 | ! This routine is a part of the Lagrangian particle model. Two Super droplets |
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| 41 | ! which fulfill certain criterion's (e.g. a big weighting factor and a small |
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| 42 | ! radius) can be merged into one super droplet with a increased number of |
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| 43 | ! represented particles of the super droplet. This mechanism ensures an |
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| 44 | ! improved a feasible amount of computational costs. The limits of particle |
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| 45 | ! creation should be chosen carefully! The idea of this algorithm is based on |
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| 46 | ! Unterstrasser and Soelch, 2014. |
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| 47 | !------------------------------------------------------------------------------! |
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| 48 | SUBROUTINE lpm_merging |
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| 49 | |
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| 50 | |
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| 51 | USE arrays_3d, & |
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| 52 | ONLY: ql |
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| 53 | |
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| 54 | USE cpulog, & |
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| 55 | ONLY: cpu_log, log_point_s |
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| 56 | |
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| 57 | USE indices, & |
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| 58 | ONLY: nxl, nxr, nyn, nys, nzb, nzt |
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| 59 | |
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| 60 | USE kinds |
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| 61 | |
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| 62 | USE particle_attributes, & |
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| 63 | ONLY: deleted_particles, grid_particles, initial_weighting_factor, & |
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[3241] | 64 | merge_drp, number_of_particles, particles, prt_count, & |
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[2263] | 65 | radius_merge, sum_merge_drp, weight_factor_merge |
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| 66 | |
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| 67 | USE pegrid |
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| 68 | |
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| 69 | IMPLICIT NONE |
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| 70 | |
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| 71 | INTEGER(iwp) :: i !< |
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| 72 | INTEGER(iwp) :: j !< |
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| 73 | INTEGER(iwp) :: k !< |
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| 74 | INTEGER(iwp) :: n !< |
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| 75 | |
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| 76 | REAL(wp) :: ql_crit = 1.0E-5_wp !< threshold lwc for cloudy grid cells |
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| 77 | !< (e.g. Siebesma et al 2003, JAS, 60) |
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| 78 | |
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| 79 | CALL cpu_log( log_point_s(81), 'lpm_merging', 'start' ) |
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| 80 | |
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| 81 | merge_drp = 0 |
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| 82 | |
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| 83 | IF ( weight_factor_merge == -1.0_wp ) THEN |
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| 84 | weight_factor_merge = 0.5_wp * initial_weighting_factor |
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| 85 | ENDIF |
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| 86 | |
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| 87 | DO i = nxl, nxr |
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| 88 | DO j = nys, nyn |
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| 89 | DO k = nzb+1, nzt |
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| 90 | |
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| 91 | number_of_particles = prt_count(k,j,i) |
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| 92 | IF ( number_of_particles <= 0 .OR. & |
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| 93 | ql(k,j,i) >= ql_crit ) CYCLE |
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| 94 | particles => grid_particles(k,j,i)%particles(1:number_of_particles) |
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| 95 | ! |
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| 96 | !-- Start merging operations: This routine delete super droplets with |
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| 97 | !-- a small radius (radius <= radius_merge) and a low weighting |
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| 98 | !-- factor (weight_factor <= weight_factor_merge). The number of |
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| 99 | !-- represented particles will be added to the next particle of the |
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| 100 | !-- particle array. Tests showed that this simplified method can be |
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| 101 | !-- used because it will only take place outside of cloudy grid |
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| 102 | !-- boxes where ql <= 1.0E-5 kg/kg. Therefore, especially former cloned |
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| 103 | !-- and subsequent evaporated super droplets will be merged. |
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| 104 | DO n = 1, number_of_particles-1 |
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| 105 | IF ( particles(n)%particle_mask .AND. & |
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| 106 | particles(n+1)%particle_mask .AND. & |
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| 107 | particles(n)%radius <= radius_merge .AND. & |
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| 108 | particles(n)%weight_factor <= weight_factor_merge ) & |
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| 109 | THEN |
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| 110 | particles(n+1)%weight_factor = & |
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| 111 | particles(n+1)%weight_factor + & |
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| 112 | ( particles(n)%radius**3 / & |
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| 113 | particles(n+1)%radius**3 * & |
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| 114 | particles(n)%weight_factor & |
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| 115 | ) |
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| 116 | particles(n)%particle_mask = .FALSE. |
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| 117 | deleted_particles = deleted_particles + 1 |
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| 118 | merge_drp = merge_drp + 1 |
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| 119 | |
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| 120 | ENDIF |
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| 121 | ENDDO |
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| 122 | ENDDO |
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| 123 | ENDDO |
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| 124 | ENDDO |
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| 125 | |
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| 126 | sum_merge_drp = sum_merge_drp + merge_drp |
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| 127 | |
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| 128 | CALL cpu_log( log_point_s(81), 'lpm_merging', 'stop' ) |
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| 129 | |
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| 130 | END SUBROUTINE lpm_merging |
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