/[MITgcm]/MITgcm/pkg/generic_advdiff/gad_dst3fl_adv_y.F
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Revision 1.8 - (hide annotations) (download)
Tue Oct 18 16:03:55 2005 UTC (18 years, 7 months ago) by jmc
Branch: MAIN
CVS Tags: checkpoint58b_post, checkpoint57y_post, checkpoint58, checkpoint58f_post, checkpoint58d_post, checkpoint58a_post, checkpoint57z_post, checkpoint57y_pre, checkpoint58e_post, checkpoint58g_post, checkpoint57w_post, checkpoint57x_post, checkpoint58c_post
Changes since 1.7: +33 -14 lines
change it to work with low tracer concentrations; add upper bound to slope
ratio theta.

1 jmc 1.8 C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_dst3fl_adv_y.F,v 1.7 2005/08/19 22:19:35 heimbach Exp $
2 jmc 1.5 C $Name: $
3 adcroft 1.1
4     #include "GAD_OPTIONS.h"
5    
6     SUBROUTINE GAD_DST3FL_ADV_Y(
7 heimbach 1.7 I bi,bj,k,deltaTloc,
8 adcroft 1.1 I vTrans, vVel,
9 jmc 1.6 I maskLocS, tracer,
10 adcroft 1.1 O vT,
11     I myThid )
12     C /==========================================================\
13     C | SUBROUTINE GAD_DST3FL_ADV_Y |
14     C | o Compute Meridional advective Flux of Tracer using |
15     C | 3rd Order DST Sceheme with flux limiting |
16     C |==========================================================|
17     IMPLICIT NONE
18    
19     C == GLobal variables ==
20     #include "SIZE.h"
21     #include "GRID.h"
22     #include "GAD.h"
23    
24     C == Routine arguments ==
25     INTEGER bi,bj,k
26 heimbach 1.7 _RL deltaTloc
27 adcroft 1.1 _RL vTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
28     _RL vVel(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
29 jmc 1.6 _RS maskLocS(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
30 adcroft 1.1 _RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
31     _RL vT (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
32     INTEGER myThid
33    
34     C == Local variables ==
35 jmc 1.5 C vFld :: velocity [m/s], meridional component
36 adcroft 1.1 INTEGER i,j
37 adcroft 1.3 _RL Rjm,Rj,Rjp,cfl,d0,d1,psiP,psiM,thetaP,thetaM
38 jmc 1.5 _RL vFld
39 jmc 1.8 _RL thetaMax
40     PARAMETER( thetaMax = 1.D+20 )
41 adcroft 1.1
42     DO i=1-Olx,sNx+Olx
43 jmc 1.8 vT(i,1-Oly)=0. _d 0
44     vT(i,2-Oly)=0. _d 0
45     vT(i,sNy+Oly)=0. _d 0
46 adcroft 1.1 ENDDO
47     DO j=1-Oly+2,sNy+Oly-1
48     DO i=1-Olx,sNx+Olx
49 jmc 1.6 Rjp=(tracer(i,j+1)-tracer(i, j ))*maskLocS(i,j+1)
50     Rj =(tracer(i, j )-tracer(i,j-1))*maskLocS(i, j )
51     Rjm=(tracer(i,j-1)-tracer(i,j-2))*maskLocS(i,j-1)
52 adcroft 1.1
53 jmc 1.5 c vFld = vVel(i,j,k,bi,bj)
54     vFld = vTrans(i,j)*recip_dxG(i,j,bi,bj)
55     & *recip_drF(k)*recip_hFacS(i,j,k,bi,bj)
56 heimbach 1.7 cfl=abs(vFld*deltaTloc*recip_dyC(i,j,bi,bj))
57 jmc 1.8 d0=(2. _d 0 -cfl)*(1. _d 0 -cfl)*oneSixth
58     d1=(1. _d 0 -cfl*cfl)*oneSixth
59    
60     C- the old version: can produce overflow, division by zero,
61     c and is wrong for tracer with low concentration:
62     c thetaP=Rjm/(1.D-20+Rj)
63     c thetaM=Rjp/(1.D-20+Rj)
64     C- the right expression, but not bounded:
65 heimbach 1.4 c thetaP=0.D0
66 jmc 1.8 c thetaM=0.D0
67 heimbach 1.4 c IF (Rj.NE.0.D0) thetaP=Rjm/Rj
68 jmc 1.8 c IF (Rj.NE.0.D0) thetaM=Rjp/Rj
69     C- prevent |thetaP,M| to reach too big value:
70     IF ( ABS(Rj)*thetaMax .LE. ABS(Rjm) ) THEN
71     thetaP=SIGN(thetaMax,Rjm*Rj)
72     ELSE
73     thetaP=Rjm/Rj
74     ENDIF
75     IF ( ABS(Rj)*thetaMax .LE. ABS(Rjp) ) THEN
76     thetaM=SIGN(thetaMax,Rjp*Rj)
77     ELSE
78     thetaM=Rjp/Rj
79     ENDIF
80    
81 adcroft 1.1 psiP=d0+d1*thetaP
82 jmc 1.8 psiP=MAX(0. _d 0, MIN(MIN(1. _d 0,psiP),
83     & thetaP*(1. _d 0 -cfl)/(cfl+1. _d -20) ))
84 adcroft 1.1 psiM=d0+d1*thetaM
85 jmc 1.8 psiM=MAX(0. _d 0, MIN(MIN(1. _d 0,psiM),
86     & thetaM*(1. _d 0 -cfl)/(cfl+1. _d -20) ))
87    
88 adcroft 1.1 vT(i,j)=
89 heimbach 1.2 & 0.5*(vTrans(i,j)+abs(vTrans(i,j)))
90     & *( Tracer(i,j-1) + psiP*Rj )
91     & +0.5*(vTrans(i,j)-abs(vTrans(i,j)))
92     & *( Tracer(i, j ) - psiM*Rj )
93 adcroft 1.1
94     ENDDO
95     ENDDO
96    
97     RETURN
98     END

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