!> @file diffusion_u.f90 !------------------------------------------------------------------------------! ! This file is part of the PALM model system. ! ! PALM is free software: you can redistribute it and/or modify it under the ! terms of the GNU General Public License as published by the Free Software ! Foundation, either version 3 of the License, or (at your option) any later ! version. ! ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY ! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR ! A PARTICULAR PURPOSE. See the GNU General Public License for more details. ! ! You should have received a copy of the GNU General Public License along with ! PALM. If not, see . ! ! Copyright 1997-2020 Leibniz Universitaet Hannover !------------------------------------------------------------------------------! ! ! Current revisions: ! ----------------- ! ! ! Former revisions: ! ----------------- ! $Id: diffusion_u.f90 4360 2020-01-07 11:25:50Z hellstea $ ! Introduction of wall_flags_total_0, which currently sets bits based on static ! topography information used in wall_flags_static_0 ! ! 4329 2019-12-10 15:46:36Z motisi ! Renamed wall_flags_0 to wall_flags_static_0 ! ! 4182 2019-08-22 15:20:23Z scharf ! Corrected "Former revisions" section ! ! 3655 2019-01-07 16:51:22Z knoop ! OpenACC port for SPEC ! ! Revision 1.1 1997/09/12 06:23:51 raasch ! Initial revision ! ! ! Description: ! ------------ !> Diffusion term of the u-component !> @todo additional damping (needed for non-cyclic bc) causes bad vectorization !> and slows down the speed on NEC about 5-10% !------------------------------------------------------------------------------! MODULE diffusion_u_mod PRIVATE PUBLIC diffusion_u INTERFACE diffusion_u MODULE PROCEDURE diffusion_u MODULE PROCEDURE diffusion_u_ij END INTERFACE diffusion_u CONTAINS !------------------------------------------------------------------------------! ! Description: ! ------------ !> Call for all grid points !------------------------------------------------------------------------------! SUBROUTINE diffusion_u USE arrays_3d, & ONLY: ddzu, ddzw, km, tend, u, v, w, drho_air, rho_air_zw USE control_parameters, & ONLY: constant_top_momentumflux, use_surface_fluxes, & use_top_fluxes USE grid_variables, & ONLY: ddx, ddx2, ddy USE indices, & ONLY: nxlu, nxr, nyn, nys, nzb, nzt, wall_flags_total_0 USE kinds USE surface_mod, & ONLY : surf_def_h, surf_def_v, surf_lsm_h, surf_lsm_v, surf_usm_h, & surf_usm_v IMPLICIT NONE INTEGER(iwp) :: i !< running index x direction INTEGER(iwp) :: j !< running index y direction INTEGER(iwp) :: k !< running index z direction INTEGER(iwp) :: l !< running index of surface type, south- or north-facing wall INTEGER(iwp) :: m !< running index surface elements INTEGER(iwp) :: surf_e !< end index of surface elements at (j,i)-gridpoint INTEGER(iwp) :: surf_s !< start index of surface elements at (j,i)-gridpoint REAL(wp) :: flag !< flag to mask topography grid points REAL(wp) :: kmym !< diffusion coefficient on southward side of the u-gridbox - interpolated onto xu-yv grid REAL(wp) :: kmyp !< diffusion coefficient on northward side of the u-gridbox - interpolated onto xu-yv grid REAL(wp) :: kmzm !< diffusion coefficient on bottom of the gridbox - interpolated onto xu-zw grid REAL(wp) :: kmzp !< diffusion coefficient on top of the gridbox - interpolated onto xu-zw grid REAL(wp) :: mask_bottom !< flag to mask vertical upward-facing surface REAL(wp) :: mask_north !< flag to mask vertical surface north of the grid point REAL(wp) :: mask_south !< flag to mask vertical surface south of the grid point REAL(wp) :: mask_top !< flag to mask vertical downward-facing surface !$ACC PARALLEL LOOP COLLAPSE(2) PRIVATE(i, j, k, l, m) & !$ACC PRIVATE(surf_e, surf_s, flag, kmym, kmyp, kmzm, kmzp) & !$ACC PRIVATE(mask_bottom, mask_north, mask_south, mask_top) & !$ACC PRESENT(wall_flags_total_0, km) & !$ACC PRESENT(u, v, w) & !$ACC PRESENT(ddzu, ddzw, drho_air, rho_air_zw) & !$ACC PRESENT(surf_def_h(0:2), surf_def_v(0:1)) & !$ACC PRESENT(surf_lsm_h, surf_lsm_v(0:1)) & !$ACC PRESENT(surf_usm_h, surf_usm_v(0:1)) & !$ACC PRESENT(tend) DO i = nxlu, nxr DO j = nys, nyn ! !-- Compute horizontal diffusion DO k = nzb+1, nzt ! !-- Predetermine flag to mask topography and wall-bounded grid points. !-- It is sufficient to masked only north- and south-facing surfaces, which !-- need special treatment for the u-component. flag = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_total_0(k,j,i), 1 ) ) mask_south = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_total_0(k,j-1,i), 1 ) ) mask_north = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_total_0(k,j+1,i), 1 ) ) ! !-- Interpolate eddy diffusivities on staggered gridpoints kmyp = 0.25_wp * & ( km(k,j,i)+km(k,j+1,i)+km(k,j,i-1)+km(k,j+1,i-1) ) kmym = 0.25_wp * & ( km(k,j,i)+km(k,j-1,i)+km(k,j,i-1)+km(k,j-1,i-1) ) tend(k,j,i) = tend(k,j,i) & + 2.0_wp * ( & km(k,j,i) * ( u(k,j,i+1) - u(k,j,i) ) & - km(k,j,i-1) * ( u(k,j,i) - u(k,j,i-1) ) & ) * ddx2 * flag & + ( mask_north * ( & kmyp * ( u(k,j+1,i) - u(k,j,i) ) * ddy & + kmyp * ( v(k,j+1,i) - v(k,j+1,i-1) ) * ddx & ) & - mask_south * ( & kmym * ( u(k,j,i) - u(k,j-1,i) ) * ddy & + kmym * ( v(k,j,i) - v(k,j,i-1) ) * ddx & ) & ) * ddy * flag ENDDO ! !-- Add horizontal momentum flux u'v' at north- (l=0) and south-facing (l=1) !-- surfaces. Note, in the the flat case, loops won't be entered as !-- start_index > end_index. Furtermore, note, no vertical natural surfaces !-- so far. !-- Default-type surfaces DO l = 0, 1 surf_s = surf_def_v(l)%start_index(j,i) surf_e = surf_def_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + & surf_def_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Natural-type surfaces DO l = 0, 1 surf_s = surf_lsm_v(l)%start_index(j,i) surf_e = surf_lsm_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_lsm_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + & surf_lsm_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Urban-type surfaces DO l = 0, 1 surf_s = surf_usm_v(l)%start_index(j,i) surf_e = surf_usm_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_usm_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + & surf_usm_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Compute vertical diffusion. In case of simulating a surface layer, !-- respective grid diffusive fluxes are masked (flag 8) within this !-- loop, and added further below, else, simple gradient approach is !-- applied. Model top is also mask if top-momentum flux is given. DO k = nzb+1, nzt ! !-- Determine flags to mask topography below and above. Flag 1 is !-- used to mask topography in general, and flag 8 implies !-- information about use_surface_fluxes. Flag 9 is used to control !-- momentum flux at model top. mask_bottom = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k-1,j,i), 8 ) ) mask_top = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k+1,j,i), 8 ) ) * & MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k+1,j,i), 9 ) ) flag = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k,j,i), 1 ) ) ! !-- Interpolate eddy diffusivities on staggered gridpoints kmzp = 0.25_wp * & ( km(k,j,i)+km(k+1,j,i)+km(k,j,i-1)+km(k+1,j,i-1) ) kmzm = 0.25_wp * & ( km(k,j,i)+km(k-1,j,i)+km(k,j,i-1)+km(k-1,j,i-1) ) tend(k,j,i) = tend(k,j,i) & + ( kmzp * ( ( u(k+1,j,i) - u(k,j,i) ) * ddzu(k+1) & + ( w(k,j,i) - w(k,j,i-1) ) * ddx & ) * rho_air_zw(k) * mask_top & - kmzm * ( ( u(k,j,i) - u(k-1,j,i) ) * ddzu(k) & + ( w(k-1,j,i) - w(k-1,j,i-1) ) * ddx & ) * rho_air_zw(k-1) * mask_bottom & ) * ddzw(k) * drho_air(k) * flag ENDDO ! !-- Vertical diffusion at the first grid point above the surface, !-- if the momentum flux at the bottom is given by the Prandtl law or !-- if it is prescribed by the user. !-- Difference quotient of the momentum flux is not formed over half !-- of the grid spacing (2.0*ddzw(k)) any more, since the comparison !-- with other (LES) models showed that the values of the momentum !-- flux becomes too large in this case. !-- The term containing w(k-1,..) (see above equation) is removed here !-- because the vertical velocity is assumed to be zero at the surface. IF ( use_surface_fluxes ) THEN ! !-- Default-type surfaces, upward-facing surf_s = surf_def_h(0)%start_index(j,i) surf_e = surf_def_h(0)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(0)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_def_h(0)%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Default-type surfaces, dowward-facing surf_s = surf_def_h(1)%start_index(j,i) surf_e = surf_def_h(1)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(1)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - surf_def_h(1)%usws(m) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Natural-type surfaces, upward-facing surf_s = surf_lsm_h%start_index(j,i) surf_e = surf_lsm_h%end_index(j,i) DO m = surf_s, surf_e k = surf_lsm_h%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_lsm_h%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Urban-type surfaces, upward-facing surf_s = surf_usm_h%start_index(j,i) surf_e = surf_usm_h%end_index(j,i) DO m = surf_s, surf_e k = surf_usm_h%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_usm_h%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ENDIF ! !-- Add momentum flux at model top IF ( use_top_fluxes .AND. constant_top_momentumflux ) THEN surf_s = surf_def_h(2)%start_index(j,i) surf_e = surf_def_h(2)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(2)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - surf_def_h(2)%usws(m) ) * ddzw(k) * drho_air(k) ENDDO ENDIF ENDDO ENDDO END SUBROUTINE diffusion_u !------------------------------------------------------------------------------! ! Description: ! ------------ !> Call for grid point i,j !------------------------------------------------------------------------------! SUBROUTINE diffusion_u_ij( i, j ) USE arrays_3d, & ONLY: ddzu, ddzw, km, tend, u, v, w, drho_air, rho_air_zw USE control_parameters, & ONLY: constant_top_momentumflux, use_surface_fluxes, & use_top_fluxes USE grid_variables, & ONLY: ddx, ddx2, ddy USE indices, & ONLY: nzb, nzt, wall_flags_total_0 USE kinds USE surface_mod, & ONLY : surf_def_h, surf_def_v, surf_lsm_h, surf_lsm_v, surf_usm_h, & surf_usm_v IMPLICIT NONE INTEGER(iwp) :: i !< running index x direction INTEGER(iwp) :: j !< running index y direction INTEGER(iwp) :: k !< running index z direction INTEGER(iwp) :: l !< running index of surface type, south- or north-facing wall INTEGER(iwp) :: m !< running index surface elements INTEGER(iwp) :: surf_e !< End index of surface elements at (j,i)-gridpoint INTEGER(iwp) :: surf_s !< Start index of surface elements at (j,i)-gridpoint REAL(wp) :: flag !< flag to mask topography grid points REAL(wp) :: kmym !< diffusion coefficient on southward side of the u-gridbox - interpolated onto xu-yv grid REAL(wp) :: kmyp ! end_index. Furtermore, note, no vertical natural surfaces !-- so far. !-- Default-type surfaces DO l = 0, 1 surf_s = surf_def_v(l)%start_index(j,i) surf_e = surf_def_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + surf_def_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Natural-type surfaces DO l = 0, 1 surf_s = surf_lsm_v(l)%start_index(j,i) surf_e = surf_lsm_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_lsm_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + surf_lsm_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Urban-type surfaces DO l = 0, 1 surf_s = surf_usm_v(l)%start_index(j,i) surf_e = surf_usm_v(l)%end_index(j,i) DO m = surf_s, surf_e k = surf_usm_v(l)%k(m) tend(k,j,i) = tend(k,j,i) + surf_usm_v(l)%mom_flux_uv(m) * ddy ENDDO ENDDO ! !-- Compute vertical diffusion. In case of simulating a surface layer, !-- respective grid diffusive fluxes are masked (flag 8) within this !-- loop, and added further below, else, simple gradient approach is !-- applied. Model top is also mask if top-momentum flux is given. DO k = nzb+1, nzt ! !-- Determine flags to mask topography below and above. Flag 1 is !-- used to mask topography in general, and flag 8 implies !-- information about use_surface_fluxes. Flag 9 is used to control !-- momentum flux at model top. mask_bottom = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k-1,j,i), 8 ) ) mask_top = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k+1,j,i), 8 ) ) * & MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k+1,j,i), 9 ) ) flag = MERGE( 1.0_wp, 0.0_wp, & BTEST( wall_flags_total_0(k,j,i), 1 ) ) ! !-- Interpolate eddy diffusivities on staggered gridpoints kmzp = 0.25_wp * ( km(k,j,i)+km(k+1,j,i)+km(k,j,i-1)+km(k+1,j,i-1) ) kmzm = 0.25_wp * ( km(k,j,i)+km(k-1,j,i)+km(k,j,i-1)+km(k-1,j,i-1) ) tend(k,j,i) = tend(k,j,i) & + ( kmzp * ( ( u(k+1,j,i) - u(k,j,i) ) * ddzu(k+1) & + ( w(k,j,i) - w(k,j,i-1) ) * ddx & ) * rho_air_zw(k) * mask_top & - kmzm * ( ( u(k,j,i) - u(k-1,j,i) ) * ddzu(k) & + ( w(k-1,j,i) - w(k-1,j,i-1) ) * ddx & ) * rho_air_zw(k-1) * mask_bottom & ) * ddzw(k) * drho_air(k) * flag ENDDO ! !-- Vertical diffusion at the first surface grid points, if the !-- momentum flux at the bottom is given by the Prandtl law or if it is !-- prescribed by the user. !-- Difference quotient of the momentum flux is not formed over half of !-- the grid spacing (2.0*ddzw(k)) any more, since the comparison with !-- other (LES) models showed that the values of the momentum flux becomes !-- too large in this case. IF ( use_surface_fluxes ) THEN ! !-- Default-type surfaces, upward-facing surf_s = surf_def_h(0)%start_index(j,i) surf_e = surf_def_h(0)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(0)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_def_h(0)%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Default-type surfaces, dowward-facing (except for model-top fluxes) surf_s = surf_def_h(1)%start_index(j,i) surf_e = surf_def_h(1)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(1)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - surf_def_h(1)%usws(m) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Natural-type surfaces, upward-facing surf_s = surf_lsm_h%start_index(j,i) surf_e = surf_lsm_h%end_index(j,i) DO m = surf_s, surf_e k = surf_lsm_h%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_lsm_h%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ! !-- Urban-type surfaces, upward-facing surf_s = surf_usm_h%start_index(j,i) surf_e = surf_usm_h%end_index(j,i) DO m = surf_s, surf_e k = surf_usm_h%k(m) tend(k,j,i) = tend(k,j,i) & + ( - ( - surf_usm_h%usws(m) ) & ) * ddzw(k) * drho_air(k) ENDDO ENDIF ! !-- Add momentum flux at model top IF ( use_top_fluxes .AND. constant_top_momentumflux ) THEN surf_s = surf_def_h(2)%start_index(j,i) surf_e = surf_def_h(2)%end_index(j,i) DO m = surf_s, surf_e k = surf_def_h(2)%k(m) tend(k,j,i) = tend(k,j,i) & + ( - surf_def_h(2)%usws(m) ) * ddzw(k) * drho_air(k) ENDDO ENDIF END SUBROUTINE diffusion_u_ij END MODULE diffusion_u_mod