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C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_dst3fl_adv_x.F,v 1.9 2006/06/07 01:55:14 heimbach Exp $ |
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C $Name: $ |
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|
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#include "GAD_OPTIONS.h" |
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|
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SUBROUTINE GAD_DST3FL_ADV_X( |
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I bi,bj,k,deltaTloc, |
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I uTrans, uFld, |
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I maskLocW, tracer, |
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O uT, |
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I myThid ) |
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C /==========================================================\ |
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C | SUBROUTINE GAD_DST3FL_ADV_X | |
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C | o Compute Zonal advective Flux of Tracer using | |
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C | 3rd Order DST Sceheme with flux limiting | |
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C |==========================================================| |
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IMPLICIT NONE |
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|
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C == GLobal variables == |
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#include "SIZE.h" |
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#include "GRID.h" |
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#include "GAD.h" |
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|
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C == Routine arguments == |
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INTEGER bi,bj,k |
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_RL deltaTloc |
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_RL uTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL uFld (1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RS maskLocW(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL uT (1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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INTEGER myThid |
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|
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C == Local variables == |
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C uLoc :: velocity [m/s], zonal component |
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INTEGER i,j |
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_RL Rjm,Rj,Rjp,cfl,d0,d1,psiP,psiM,thetaP,thetaM |
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_RL uLoc |
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_RL thetaMax |
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PARAMETER( thetaMax = 1.D+20 ) |
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|
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C- jmc: an alternative would be to compute directly psiM*Rj & psiP*Rj |
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C (if Rj*Rjm < 0 => psiP*Rj = 0 , elsef Rj > 0 ... , else ... ) |
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C with no need to compute thetaM (might be easier to differentiate) |
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|
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DO j=1-Oly,sNy+Oly |
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uT(1-Olx,j)=0. _d 0 |
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uT(2-Olx,j)=0. _d 0 |
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uT(sNx+Olx,j)=0. _d 0 |
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DO i=1-Olx+2,sNx+Olx-1 |
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Rjp=(tracer(i+1,j)-tracer( i ,j))*maskLocW(i+1,j) |
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Rj =(tracer( i ,j)-tracer(i-1,j))*maskLocW( i ,j) |
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Rjm=(tracer(i-1,j)-tracer(i-2,j))*maskLocW(i-1,j) |
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|
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c uLoc = uFld(i,j) |
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uLoc = uTrans(i,j)*recip_dyG(i,j,bi,bj) |
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& *recip_drF(k)*_recip_hFacW(i,j,k,bi,bj) |
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cfl=abs(uLoc*deltaTloc*recip_dxC(i,j,bi,bj)) |
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d0=(2. _d 0 -cfl)*(1. _d 0 -cfl)*oneSixth |
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d1=(1. _d 0 -cfl*cfl)*oneSixth |
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|
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C- the old version: can produce overflow, division by zero, |
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c and is wrong for tracer with low concentration: |
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c thetaP=Rjm/(1.D-20+Rj) |
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c thetaM=Rjp/(1.D-20+Rj) |
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C- the right expression, but not bounded: |
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c thetaP=0.D0 |
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c thetaM=0.D0 |
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c IF (Rj.NE.0.D0) thetaP=Rjm/Rj |
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c IF (Rj.NE.0.D0) thetaM=Rjp/Rj |
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C- prevent |thetaP,M| to reach too big value: |
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IF ( ABS(Rj)*thetaMax .LE. ABS(Rjm) ) THEN |
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thetaP=SIGN(thetaMax,Rjm*Rj) |
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ELSE |
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thetaP=Rjm/Rj |
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ENDIF |
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IF ( ABS(Rj)*thetaMax .LE. ABS(Rjp) ) THEN |
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thetaM=SIGN(thetaMax,Rjp*Rj) |
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ELSE |
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thetaM=Rjp/Rj |
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ENDIF |
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|
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psiP=d0+d1*thetaP |
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psiP=MAX(0. _d 0, MIN(MIN(1. _d 0,psiP), |
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& thetaP*(1. _d 0 -cfl)/(cfl+1. _d -20) )) |
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psiM=d0+d1*thetaM |
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psiM=MAX(0. _d 0, MIN(MIN(1. _d 0,psiM), |
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& thetaM*(1. _d 0 -cfl)/(cfl+1. _d -20) )) |
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|
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uT(i,j)= |
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& 0.5*(uTrans(i,j)+abs(uTrans(i,j))) |
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& *( Tracer(i-1,j) + psiP*Rj ) |
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& +0.5*(uTrans(i,j)-abs(uTrans(i,j))) |
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& *( Tracer( i ,j) - psiM*Rj ) |
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|
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ENDDO |
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ENDDO |
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|
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RETURN |
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END |
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