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dgoldberg |
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C $Header: /u/gcmpack/MITgcm/pkg/mom_common/mom_u_bottomdrag.F,v 1.17 2015/01/04 16:16:32 jmc Exp $ |
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C $Name: $ |
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#include "MOM_COMMON_OPTIONS.h" |
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#ifdef ALLOW_CTRL |
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# include "CTRL_OPTIONS.h" |
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#endif |
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CBOP |
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C !ROUTINE: MOM_U_BOTTOMDRAG |
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C !INTERFACE: ========================================================== |
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SUBROUTINE MOM_U_BOTTOMDRAG( |
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I bi, bj, k, |
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I uFld, vFld, KE, kappaRU, |
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O uDragTerms, |
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I myThid ) |
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C !DESCRIPTION: |
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C Calculates the drag due to friction and the no-slip condition at bottom: |
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C \begin{equation*} |
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C G^u_{drag} = - \frac{1}{\Delta r_f} ( r_b + C_D |v| + \frac{2}{\Delta r_c} ) u |
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C \end{equation*} |
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C !USES: =============================================================== |
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IMPLICIT NONE |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "PARAMS.h" |
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#include "GRID.h" |
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#ifdef ALLOW_CTRL |
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# include "CTRL_FIELDS.h" |
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#endif |
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C !INPUT PARAMETERS: =================================================== |
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C bi,bj :: tile indices |
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C k :: vertical level |
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C uFld :: zonal flow |
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C vFld :: meridional flow |
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C KE :: Kinetic energy |
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C kappaRU :: vertical viscosity |
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C myThid :: thread number |
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INTEGER bi,bj,k |
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_RL uFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL vFld(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL KE(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL kappaRU(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr+1) |
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INTEGER myThid |
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C !OUTPUT PARAMETERS: ================================================== |
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C uDragTerms :: drag term |
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_RL uDragTerms(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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C !LOCAL VARIABLES: ==================================================== |
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C i,j :: loop indices |
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INTEGER i,j,kDown,kLowF,kBottom |
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_RL viscFac, dragFac, uSq |
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_RL recDrC |
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_RL recDrF_bot(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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CEOP |
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C- No-slip BCs impose a drag at bottom |
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viscFac = 0. |
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IF (no_slip_bottom) viscFac = 2. |
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IF ( usingZCoords ) THEN |
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kBottom = Nr |
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kDown = MIN(k+1,Nr) |
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kLowF = k+1 |
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c dragFac = mass2rUnit*rhoConst |
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c dragFac = wUnit2rVel(k+1) |
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dragFac = 1. _d 0 |
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ELSE |
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kBottom = 1 |
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kDown = MAX(k-1,1) |
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kLowF = k |
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dragFac = mass2rUnit*rhoConst |
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c dragFac = wUnit2rVel(k) |
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ENDIF |
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IF ( k.EQ.kBottom ) THEN |
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recDrC = recip_drF(k) |
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DO j=1-OLy,sNy+OLy |
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DO i=1-OLx,sNx+OLx |
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recDrF_bot(i,j) = _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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ENDDO |
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ENDDO |
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ELSE |
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recDrC = recip_drC(kLowF) |
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DO j=1-OLy,sNy+OLy |
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DO i=1-OLx,sNx+OLx |
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recDrF_bot(i,j) = _recip_hFacW(i,j,k,bi,bj)*recip_drF(k) |
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& * ( 1. _d 0 -_maskW(i,j,kDown,bi,bj) ) |
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ENDDO |
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ENDDO |
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ENDIF |
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C-- Linear bottom drag: |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uDragTerms(i,j) = |
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& - recDrF_bot(i,j) |
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& *( bottomDragLinear*dragFac |
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#ifdef ALLOW_BOTTOMDRAG_CONTROL |
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& + halfRL*( bottomDragFld(i-1,j,bi,bj) |
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& + bottomDragFld(i,j,bi,bj) )*dragFac |
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#endif |
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& ) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDDO |
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ENDDO |
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C-- Add friction at the bottom (no-slip BC) |
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IF ( no_slip_bottom .AND. bottomVisc_pCell ) THEN |
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C- bottom friction accounts for true distance (including hFac) to the bottom |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *( kappaRU(i,j,kLowF)*recDrC*viscFac |
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& *_recip_hFacW(i,j,k,bi,bj) |
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& ) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDDO |
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ENDDO |
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ELSEIF ( no_slip_bottom ) THEN |
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C- ignores partial-cell reduction of the distance to the bottom |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *( kappaRU(i,j,kLowF)*recDrC*viscFac |
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& ) |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDDO |
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ENDDO |
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ENDIF |
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C-- Add quadratic bottom drag |
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IF ( selectBotDragQuadr.EQ.0 ) THEN |
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C- average grid-cell-center KE to get velocity norm @ U.pt |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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IF ( (KE(i,j)+KE(i-1,j)) .GT. 0. ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(KE(i,j)+KE(i-1,j))*dragFac |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.EQ.1 ) THEN |
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C- calculate locally velocity norm @ U.pt (local U & 4 V averaged) |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uSq = uFld(i,j)*uFld(i,j) |
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& + ( (vFld(i-1, j )*vFld(i-1, j )*hFacS(i-1, j ,k,bi,bj) |
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& +vFld( i , j )*vFld( i , j )*hFacS( i , j ,k,bi,bj)) |
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& + (vFld(i-1,j+1)*vFld(i-1,j+1)*hFacS(i-1,j+1,k,bi,bj) |
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& +vFld( i ,j+1)*vFld( i ,j+1)*hFacS( i ,j+1,k,bi,bj)) |
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& )*recip_hFacW(i,j,k,bi,bj)*0.25 _d 0 |
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IF ( uSq.GT.zeroRL ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(uSq)*dragFac |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.EQ.2 ) THEN |
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C- same as above but using wet-point method to average 4 V |
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DO j=1-OLy,sNy+OLy-1 |
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DO i=1-OLx+1,sNx+OLx-1 |
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uSq = ( hFacS(i-1, j ,k,bi,bj) + hFacS( i , j ,k,bi,bj) ) |
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& + ( hFacS(i-1,j+1,k,bi,bj) + hFacS( i ,j+1,k,bi,bj) ) |
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IF ( uSq.GT.zeroRL ) THEN |
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uSq = uFld(i,j)*uFld(i,j) |
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& +( (vFld(i-1, j )*vFld(i-1, j )*hFacS(i-1, j ,k,bi,bj) |
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& +vFld( i , j )*vFld( i , j )*hFacS( i , j ,k,bi,bj)) |
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& + (vFld(i-1,j+1)*vFld(i-1,j+1)*hFacS(i-1,j+1,k,bi,bj) |
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& +vFld( i ,j+1)*vFld( i ,j+1)*hFacS( i ,j+1,k,bi,bj)) |
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& )/uSq |
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ELSE |
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uSq = uFld(i,j)*uFld(i,j) |
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ENDIF |
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IF ( uSq.GT.zeroRL ) THEN |
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uDragTerms(i,j) = uDragTerms(i,j) |
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& - recDrF_bot(i,j) |
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& *bottomDragQuadratic*SQRT(uSq)*dragFac |
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#ifndef IMPLICIT_BOTTOMSIDEDRAG |
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& * uFld(i,j) |
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#endif |
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ENDIF |
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ENDDO |
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ENDDO |
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ELSEIF ( selectBotDragQuadr.NE.-1 ) THEN |
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STOP 'MOM_U_BOTTOMDRAG: invalid selectBotDragQuadr value' |
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ENDIF |
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#ifdef IMPLICIT_BOTTOMSIDEDRAG |
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DO j=1-OLy+1,sNy+OLy-1 |
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DO i=1-OLx,sNx+OLx-1 |
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uDragTerms(i,j) = uDragTerms(i,j)*uFld(i,j) / |
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& (1. - deltaTmom*uDragTerms(i,j)) |
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ENDDO |
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ENDDO |
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#endif |
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#ifdef ALLOW_DIAGNOSTICS |
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IF (useDiagnostics) THEN |
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CALL DIAGNOSTICS_FILL(uDragTerms,'UBotDrag',k,1,2,bi,bj,myThid) |
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ENDIF |
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#endif /* ALLOW_DIAGNOSTICS */ |
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RETURN |
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END |
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