1 | !> @file timestep.f90 |
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2 | !--------------------------------------------------------------------------------------------------! |
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3 | ! This file is part of the PALM model system. |
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4 | ! |
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5 | ! PALM is free software: you can redistribute it and/or modify it under the terms of the GNU General |
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6 | ! Public License as published by the Free Software Foundation, either version 3 of the License, or |
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7 | ! (at your option) any later version. |
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8 | ! |
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9 | ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the |
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10 | ! implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General |
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11 | ! Public License for more details. |
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12 | ! |
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13 | ! You should have received a copy of the GNU General Public License along with PALM. If not, see |
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14 | ! <http://www.gnu.org/licenses/>. |
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15 | ! |
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16 | ! Copyright 1997-2020 Leibniz Universitaet Hannover |
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17 | !--------------------------------------------------------------------------------------------------! |
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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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26 | ! $Id: timestep.f90 4564 2020-06-12 14:03:36Z raasch $ |
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27 | ! Vertical nesting method of Huq et al. (2019) removed |
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28 | ! |
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29 | ! 4540 2020-05-18 15:23:29Z raasch |
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30 | ! File re-formatted to follow the PALM coding standard |
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31 | ! |
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32 | ! |
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33 | ! 4444 2020-03-05 15:59:50Z raasch |
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34 | ! Bugfix: cpp-directives for serial mode added |
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35 | ! |
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36 | ! 4360 2020-01-07 11:25:50Z suehring |
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37 | ! Added missing OpenMP directives |
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38 | ! |
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39 | ! 4233 2019-09-20 09:55:54Z knoop |
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40 | ! OpenACC data update host removed |
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41 | ! |
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42 | ! 4182 2019-08-22 15:20:23Z scharf |
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43 | ! Corrected "Former revisions" section |
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44 | ! |
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45 | ! 4101 2019-07-17 15:14:26Z gronemeier |
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46 | ! - Consider 2*Km within diffusion criterion as Km is considered twice within the diffusion of e, |
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47 | ! - in RANS mode, instead of considering each wind component individually use the wind speed of 3d |
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48 | ! wind vector in CFL criterion |
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49 | ! - Do not limit the increase of dt based on its previous value in RANS mode |
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50 | ! |
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51 | ! 3658 2019-01-07 20:28:54Z knoop |
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52 | ! OpenACC port for SPEC |
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53 | ! |
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54 | ! Revision 1.1 1997/08/11 06:26:19 raasch |
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55 | ! Initial revision |
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56 | ! |
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57 | ! |
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58 | ! Description: |
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59 | ! ------------ |
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60 | !> Compute the time step under consideration of the FCL and diffusion criterion. |
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61 | !--------------------------------------------------------------------------------------------------! |
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62 | SUBROUTINE timestep |
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63 | |
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64 | |
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65 | USE arrays_3d, & |
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66 | ONLY: dzu, & |
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67 | dzw, & |
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68 | kh, & |
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69 | km, & |
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70 | u, & |
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71 | u_stokes_zu, & |
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72 | v, & |
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73 | v_stokes_zu, & |
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74 | w |
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75 | |
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76 | USE control_parameters, & |
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77 | ONLY: cfl_factor, & |
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78 | dt_3d, & |
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79 | dt_fixed, & |
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80 | dt_max, & |
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81 | galilei_transformation, & |
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82 | message_string, & |
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83 | rans_mode, & |
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84 | stop_dt, & |
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85 | timestep_reason, & |
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86 | u_gtrans, & |
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87 | use_ug_for_galilei_tr, & |
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88 | v_gtrans |
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89 | |
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90 | #if defined( __parallel ) |
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91 | USE control_parameters, & |
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92 | ONLY: coupling_mode, & |
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93 | terminate_coupled, & |
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94 | terminate_coupled_remote |
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95 | #endif |
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96 | |
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97 | USE cpulog, & |
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98 | ONLY: cpu_log, & |
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99 | log_point |
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100 | |
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101 | USE grid_variables, & |
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102 | ONLY: dx, & |
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103 | dx2, & |
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104 | dy, & |
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105 | dy2 |
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106 | |
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107 | USE indices, & |
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108 | ONLY: nxl, & |
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109 | nxlg, & |
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110 | nxr, & |
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111 | nxrg, & |
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112 | nyn, & |
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113 | nyng, & |
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114 | nys, & |
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115 | nysg, & |
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116 | nzb, & |
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117 | nzt |
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118 | |
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119 | USE interfaces |
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120 | |
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121 | USE kinds |
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122 | |
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123 | USE bulk_cloud_model_mod, & |
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124 | ONLY: dt_precipitation |
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125 | |
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126 | USE pegrid |
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127 | |
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128 | USE pmc_interface, & |
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129 | ONLY: nested_run |
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130 | |
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131 | USE statistics, & |
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132 | ONLY: flow_statistics_called, & |
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133 | hom, & |
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134 | u_max, & |
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135 | u_max_ijk, & |
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136 | v_max, & |
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137 | v_max_ijk, & |
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138 | w_max, & |
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139 | w_max_ijk |
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140 | |
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141 | IMPLICIT NONE |
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142 | |
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143 | INTEGER(iwp) :: i !< |
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144 | INTEGER(iwp) :: j !< |
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145 | INTEGER(iwp) :: k !< |
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146 | INTEGER(iwp) :: km_max_ijk(3) = -1 !< index values (i,j,k) of location where km_max occurs |
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147 | INTEGER(iwp) :: kh_max_ijk(3) = -1 !< index values (i,j,k) of location where kh_max occurs |
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148 | |
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149 | LOGICAL :: stop_dt_local !< local switch for controlling the time stepping |
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150 | |
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151 | REAL(wp) :: div !< |
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152 | REAL(wp) :: dt_diff !< |
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153 | REAL(wp) :: dt_diff_l !< |
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154 | REAL(wp) :: dt_u !< |
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155 | REAL(wp) :: dt_u_l !< |
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156 | REAL(wp) :: dt_v !< |
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157 | REAL(wp) :: dt_v_l !< |
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158 | REAL(wp) :: dt_w !< |
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159 | REAL(wp) :: dt_w_l !< |
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160 | REAL(wp) :: km_max !< maximum of Km in entire domain |
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161 | REAL(wp) :: kh_max !< maximum of Kh in entire domain |
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162 | REAL(wp) :: u_gtrans_l !< |
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163 | REAL(wp) :: v_gtrans_l !< |
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164 | |
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165 | REAL(wp), DIMENSION(2) :: uv_gtrans_l !< |
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166 | #if defined( __parallel ) |
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167 | REAL(wp), DIMENSION(2) :: uv_gtrans !< |
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168 | REAL(wp), DIMENSION(3) :: reduce !< |
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169 | REAL(wp), DIMENSION(3) :: reduce_l !< |
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170 | #endif |
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171 | REAL(wp), DIMENSION(nzb+1:nzt) :: dxyz2_min !< |
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172 | !$ACC DECLARE CREATE(dxyz2_min) |
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173 | |
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174 | |
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175 | CALL cpu_log( log_point(12), 'calculate_timestep', 'start' ) |
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176 | |
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177 | ! |
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178 | !-- In case of Galilei-transform not using the geostrophic wind as translation velocity, compute the |
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179 | !-- volume-averaged horizontal velocity components, which will then be subtracted from the |
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180 | !-- horizontal wind for the time step and horizontal advection routines. |
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181 | IF ( galilei_transformation .AND. .NOT. use_ug_for_galilei_tr ) THEN |
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182 | IF ( flow_statistics_called ) THEN |
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183 | ! |
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184 | !-- Horizontal averages already existent, just need to average them vertically. |
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185 | u_gtrans = 0.0_wp |
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186 | v_gtrans = 0.0_wp |
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187 | DO k = nzb+1, nzt |
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188 | u_gtrans = u_gtrans + hom(k,1,1,0) |
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189 | v_gtrans = v_gtrans + hom(k,1,2,0) |
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190 | ENDDO |
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191 | u_gtrans = u_gtrans / REAL( nzt - nzb, KIND = wp ) |
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192 | v_gtrans = v_gtrans / REAL( nzt - nzb, KIND = wp ) |
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193 | ELSE |
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194 | ! |
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195 | !-- Averaging over the entire model domain. |
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196 | u_gtrans_l = 0.0_wp |
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197 | v_gtrans_l = 0.0_wp |
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198 | DO i = nxl, nxr |
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199 | DO j = nys, nyn |
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200 | DO k = nzb+1, nzt |
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201 | u_gtrans_l = u_gtrans_l + u(k,j,i) |
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202 | v_gtrans_l = v_gtrans_l + v(k,j,i) |
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203 | ENDDO |
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204 | ENDDO |
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205 | ENDDO |
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206 | uv_gtrans_l(1) = u_gtrans_l / REAL( (nxr-nxl+1) * (nyn-nys+1) * (nzt-nzb), KIND = wp ) |
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207 | uv_gtrans_l(2) = v_gtrans_l / REAL( (nxr-nxl+1) * (nyn-nys+1) * (nzt-nzb), KIND = wp ) |
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208 | #if defined( __parallel ) |
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209 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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210 | CALL MPI_ALLREDUCE( uv_gtrans_l, uv_gtrans, 2, MPI_REAL, MPI_SUM, comm2d, ierr ) |
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211 | u_gtrans = uv_gtrans(1) / REAL( numprocs, KIND = wp ) |
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212 | v_gtrans = uv_gtrans(2) / REAL( numprocs, KIND = wp ) |
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213 | #else |
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214 | u_gtrans = uv_gtrans_l(1) |
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215 | v_gtrans = uv_gtrans_l(2) |
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216 | #endif |
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217 | ENDIF |
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218 | ENDIF |
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219 | |
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220 | ! |
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221 | !-- Determine the maxima of the velocity components, including their grid index positions. |
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222 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, u, 'abs', 0.0_wp, u_max, u_max_ijk ) |
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223 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, v, 'abs', 0.0_wp, v_max, v_max_ijk ) |
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224 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, w, 'abs', 0.0_wp, w_max, w_max_ijk ) |
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225 | |
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226 | IF ( .NOT. dt_fixed ) THEN |
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227 | ! |
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228 | !-- Variable time step: |
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229 | !-- Calculate the maximum time step according to the CFL-criterion |
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230 | dt_u_l = 999999.9_wp |
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231 | dt_v_l = 999999.9_wp |
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232 | dt_w_l = 999999.9_wp |
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233 | |
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234 | IF ( .NOT. rans_mode ) THEN |
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235 | ! |
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236 | !-- Consider each velocity component individually |
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237 | |
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238 | !$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i,j,k) & |
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239 | !$ACC COPY(dt_u_l, dt_v_l, dt_w_l, u_stokes_zu, v_stokes_zu) & |
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240 | !$ACC REDUCTION(MIN: dt_u_l, dt_v_l, dt_w_l) & |
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241 | !$ACC PRESENT(u, v, w, dzu) |
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242 | !$OMP PARALLEL DO PRIVATE(i,j,k) & |
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243 | !$OMP REDUCTION(MIN: dt_u_l, dt_v_l, dt_w_l) |
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244 | DO i = nxl, nxr |
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245 | DO j = nys, nyn |
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246 | DO k = nzb+1, nzt |
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247 | dt_u_l = MIN( dt_u_l, ( dx / ( ABS( u(k,j,i) - u_gtrans + u_stokes_zu(k) ) & |
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248 | + 1.0E-10_wp ) ) ) |
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249 | dt_v_l = MIN( dt_v_l, ( dy / ( ABS( v(k,j,i) - v_gtrans + v_stokes_zu(k) ) & |
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250 | + 1.0E-10_wp ) ) ) |
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251 | dt_w_l = MIN( dt_w_l, ( dzu(k) / ( ABS( w(k,j,i) ) + 1.0E-10_wp ) ) ) |
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252 | ENDDO |
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253 | ENDDO |
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254 | ENDDO |
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255 | |
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256 | ELSE |
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257 | ! |
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258 | !-- Consider the wind speed at the scalar-grid point |
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259 | !-- !> @note Considering the wind speed instead of each individual wind component is only a |
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260 | !-- !> workaround so far. This has to be changed in the future. |
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261 | |
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262 | !$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i,j,k) & |
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263 | !$ACC COPY(dt_u_l, u_stokes_zu, v_stokes_zu) & |
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264 | !$ACC REDUCTION(MIN: dt_u_l) & |
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265 | !$ACC PRESENT(u, v, w, dzu) |
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266 | !$OMP PARALLEL DO PRIVATE(i,j,k) & |
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267 | !$OMP REDUCTION(MIN: dt_u_l) |
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268 | DO i = nxl, nxr |
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269 | DO j = nys, nyn |
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270 | DO k = nzb+1, nzt |
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271 | dt_u_l = MIN( dt_u_l, ( MIN( dx, dy, dzu(k) ) / ( SQRT( & |
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272 | ( 0.5 * ( u(k,j,i) + u(k,j,i+1) ) - u_gtrans + u_stokes_zu(k) )**2 & |
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273 | + ( 0.5 * ( v(k,j,i) + v(k,j+1,i) ) - v_gtrans + v_stokes_zu(k) )**2 & |
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274 | + ( 0.5 * ( w(k,j,i) + w(k-1,j,i) ) )**2 ) + 1.0E-10_wp ) ) ) |
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275 | ENDDO |
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276 | ENDDO |
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277 | ENDDO |
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278 | |
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279 | dt_v_l = dt_u_l |
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280 | dt_w_l = dt_u_l |
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281 | |
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282 | ENDIF |
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283 | |
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284 | #if defined( __parallel ) |
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285 | reduce_l(1) = dt_u_l |
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286 | reduce_l(2) = dt_v_l |
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287 | reduce_l(3) = dt_w_l |
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288 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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289 | CALL MPI_ALLREDUCE( reduce_l, reduce, 3, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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290 | dt_u = reduce(1) |
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291 | dt_v = reduce(2) |
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292 | dt_w = reduce(3) |
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293 | #else |
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294 | dt_u = dt_u_l |
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295 | dt_v = dt_v_l |
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296 | dt_w = dt_w_l |
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297 | #endif |
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298 | |
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299 | ! |
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300 | !-- Compute time step according to the diffusion criterion. |
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301 | !-- First calculate minimum grid spacing which only depends on index k. When using the dynamic |
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302 | !-- subgrid model, negative km are possible. |
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303 | dt_diff_l = 999999.0_wp |
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304 | |
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305 | !$ACC PARALLEL LOOP PRESENT(dxyz2_min, dzw) |
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306 | DO k = nzb+1, nzt |
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307 | dxyz2_min(k) = MIN( dx2, dy2, dzw(k) * dzw(k) ) * 0.125_wp |
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308 | ENDDO |
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309 | |
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310 | !$OMP PARALLEL private(i,j,k) reduction(MIN: dt_diff_l) |
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311 | !$OMP DO |
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312 | !$ACC PARALLEL LOOP COLLAPSE(3) PRIVATE(i,j,k) & |
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313 | !$ACC COPY(dt_diff_l) REDUCTION(MIN: dt_diff_l) & |
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314 | !$ACC PRESENT(dxyz2_min, kh, km) |
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315 | DO i = nxl, nxr |
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316 | DO j = nys, nyn |
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317 | DO k = nzb+1, nzt |
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318 | dt_diff_l = MIN( dt_diff_l, dxyz2_min(k) / ( MAX( kh(k,j,i), 2.0_wp * & |
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319 | ABS( km(k,j,i) ) ) + 1E-20_wp ) ) |
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320 | ENDDO |
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321 | ENDDO |
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322 | ENDDO |
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323 | !$OMP END PARALLEL |
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324 | #if defined( __parallel ) |
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325 | IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr ) |
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326 | CALL MPI_ALLREDUCE( dt_diff_l, dt_diff, 1, MPI_REAL, MPI_MIN, comm2d, ierr ) |
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327 | #else |
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328 | dt_diff = dt_diff_l |
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329 | #endif |
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330 | |
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331 | ! |
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332 | !-- The time step is the minimum of the 3-4 components and the diffusion time step minus a |
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333 | !-- reduction (cfl_factor) to be on the safe side. |
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334 | !-- The time step must not exceed the maximum allowed value. |
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335 | dt_3d = cfl_factor * MIN( dt_diff, dt_u, dt_v, dt_w, dt_precipitation ) |
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336 | dt_3d = MIN( dt_3d, dt_max ) |
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337 | |
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338 | ! |
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339 | !-- Remember the restricting time step criterion for later output. |
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340 | IF ( MIN( dt_u, dt_v, dt_w ) < dt_diff ) THEN |
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341 | timestep_reason = 'A' |
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342 | ELSE |
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343 | timestep_reason = 'D' |
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344 | ENDIF |
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345 | |
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346 | ! |
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347 | !-- Set flag if the time step becomes too small. |
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348 | IF ( dt_3d < ( 0.00001_wp * dt_max ) ) THEN |
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349 | stop_dt = .TRUE. |
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350 | |
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351 | ! |
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352 | !-- Determine the maxima of the diffusion coefficients, including their grid index positions. |
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353 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, km, 'abs', 0.0_wp, km_max, & |
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354 | km_max_ijk ) |
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355 | CALL global_min_max( nzb, nzt+1, nysg, nyng, nxlg, nxrg, kh, 'abs', 0.0_wp, kh_max, & |
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356 | kh_max_ijk ) |
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357 | |
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358 | WRITE( message_string, * ) 'Time step has reached minimum limit.', & |
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359 | '&dt = ', dt_3d, ' s Simulation is terminated.', & |
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360 | '&dt_u = ', dt_u, ' s', & |
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361 | '&dt_v = ', dt_v, ' s', & |
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362 | '&dt_w = ', dt_w, ' s', & |
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363 | '&dt_diff = ', dt_diff, ' s', & |
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364 | '&u_max = ', u_max, ' m/s k=', u_max_ijk(1), & |
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365 | ' j=', u_max_ijk(2), ' i=', u_max_ijk(3), & |
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366 | '&v_max = ', v_max, ' m/s k=', v_max_ijk(1), & |
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367 | ' j=', v_max_ijk(2), ' i=', v_max_ijk(3), & |
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368 | '&w_max = ', w_max, ' m/s k=', w_max_ijk(1), & |
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369 | ' j=', w_max_ijk(2), ' i=', w_max_ijk(3), & |
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370 | '&km_max = ', km_max, ' m2/s2 k=', km_max_ijk(1), & |
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371 | ' j=', km_max_ijk(2), ' i=', km_max_ijk(3), & |
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372 | '&kh_max = ', kh_max, ' m2/s2 k=', kh_max_ijk(1), & |
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373 | ' j=', kh_max_ijk(2), ' i=', kh_max_ijk(3) |
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374 | CALL message( 'timestep', 'PA0312', 0, 1, 0, 6, 0 ) |
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375 | ! |
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376 | !-- In case of coupled runs inform the remote model of the termination and its reason, |
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377 | !-- provided the remote model has not already been informed of another termination reason |
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378 | !-- (terminate_coupled > 0). |
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379 | #if defined( __parallel ) |
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380 | IF ( coupling_mode /= 'uncoupled' .AND. terminate_coupled == 0 ) THEN |
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381 | terminate_coupled = 2 |
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382 | IF ( myid == 0 ) THEN |
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383 | CALL MPI_SENDRECV( terminate_coupled, 1, MPI_INTEGER, target_id, 0, & |
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384 | terminate_coupled_remote, 1, MPI_INTEGER, target_id, 0, & |
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385 | comm_inter, status, ierr ) |
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386 | ENDIF |
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387 | CALL MPI_BCAST( terminate_coupled_remote, 1, MPI_INTEGER, 0, comm2d, ierr) |
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388 | ENDIF |
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389 | #endif |
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390 | ENDIF |
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391 | |
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392 | ! |
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393 | !-- In case of nested runs all parent/child processes have to terminate if one process has set |
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394 | !-- the stop flag, i.e. they need to set the stop flag too. |
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395 | IF ( nested_run ) THEN |
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396 | stop_dt_local = stop_dt |
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397 | #if defined( __parallel ) |
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398 | CALL MPI_ALLREDUCE( stop_dt_local, stop_dt, 1, MPI_LOGICAL, MPI_LOR, MPI_COMM_WORLD, ierr ) |
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399 | #endif |
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400 | ENDIF |
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401 | |
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402 | ! |
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403 | !-- Ensure a smooth value (two significant digits) of the timestep. |
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404 | div = 1000.0_wp |
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405 | DO WHILE ( dt_3d < div ) |
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406 | div = div / 10.0_wp |
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407 | ENDDO |
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408 | dt_3d = NINT( dt_3d * 100.0_wp / div ) * div / 100.0_wp |
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409 | |
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410 | ENDIF |
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411 | |
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412 | CALL cpu_log( log_point(12), 'calculate_timestep', 'stop' ) |
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413 | |
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414 | END SUBROUTINE timestep |
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