/[MITgcm]/MITgcm/pkg/seaice/seaice_jfnk.F
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Revision 1.1 - (hide annotations) (download)
Tue Oct 16 07:00:21 2012 UTC (12 years, 8 months ago) by mlosch
Branch: MAIN
add JFNK-solver routines, mostly parallel and mult-threaded (except
for FGMRES)

1 mlosch 1.1 C $Header: $
2     C $Name: $
3    
4     #include "SEAICE_OPTIONS.h"
5    
6     CBOP
7     C !ROUTINE: SEAICE_JFNK
8     C !INTERFACE:
9     SUBROUTINE SEAICE_JFNK( myTime, myIter, myThid )
10    
11     C !DESCRIPTION: \bv
12     C *==========================================================*
13     C | SUBROUTINE SEAICE_JFKF
14     C | o Ice dynamics using a Jacobian-free Newton-Krylov solver
15     C | following J.-F. Lemieux et al. Improving the numerical
16     C | convergence of viscous-plastic sea ice models with the
17     C | Jacobian-free Newton-Krylov method. J. Comp. Phys. 229,
18     C | 2840-2852 (2010).
19     C | o The logic follows JFs code.
20     C *==========================================================*
21     C | written by Martin Losch, Oct 2012
22     C *==========================================================*
23     C \ev
24    
25     C !USES:
26     IMPLICIT NONE
27    
28     C === Global variables ===
29     #include "SIZE.h"
30     #include "EEPARAMS.h"
31     #include "PARAMS.h"
32     #include "DYNVARS.h"
33     #include "GRID.h"
34     #include "SEAICE_SIZE.h"
35     #include "SEAICE_PARAMS.h"
36     #include "SEAICE.h"
37    
38     #ifdef ALLOW_AUTODIFF_TAMC
39     # include "tamc.h"
40     #endif
41    
42     C !INPUT/OUTPUT PARAMETERS:
43     C === Routine arguments ===
44     C myTime :: Simulation time
45     C myIter :: Simulation timestep number
46     C myThid :: my Thread Id. number
47     _RL myTime
48     INTEGER myIter
49     INTEGER myThid
50    
51     #if ( (defined SEAICE_CGRID) && \
52     (defined SEAICE_ALLOW_JFNK) && \
53     (defined SEAICE_ALLOW_DYNAMICS) )
54    
55     C i,j,bi,bj :: loop indices
56     INTEGER i,j,bi,bj
57     C loop indices
58     INTEGER newtonIter, newtonIterFail
59     INTEGER krylovIter, krylovIterFail
60     INTEGER totalKrylovIter
61     C FGMRES flag that indicates what to do next
62     INTEGER iCode
63     _RL JFNKresidual, JFNKresidualTile(nSx,nSy)
64     _RL JFNKresidualKm1
65     C parameters to compute convergence criterion
66     _RL phi_e, alp_e, JFNKgamma_lin
67     _RL FGMRESeps
68     _RL JFNKtol
69     C
70     _RL recip_deltaT
71     LOGICAL JFNKconverged, krylovConverged
72     CHARACTER*(MAX_LEN_MBUF) msgBuf
73     C
74     C u/vIceRes :: residual of sea-ice momentum equations
75     _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
76     _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
77     C du/vIce :: ice velocity increment to be added to u/vIce
78     _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
79     _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
80     C precomputed (= constant per Newton iteration) versions of
81     C zeta, eta, and DWATN
82     _RL zetaPre(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
83     _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
84     _RL dwatPre(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
85     CEOP
86    
87     C Initialise
88     newtonIter = 0
89     newtonIterFail = 0
90     krylovIterFail = 0
91     totalKrylovIter = 0
92     JFNKconverged = .FALSE.
93     JFNKtol = 0. _d 0
94     JFNKresidual = 0. _d 0
95     JFNKresidualKm1 = 0. _d 0
96     FGMRESeps = 0. _d 0
97     recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
98     C
99     DO bj=myByLo(myThid),myByHi(myThid)
100     DO bi=myBxLo(myThid),myBxHi(myThid)
101     DO J=1-Oly,sNy+Oly
102     DO I=1-Olx,sNx+Olx
103     uIceRes(I,J,bi,bj) = 0. _d 0
104     vIceRes(I,J,bi,bj) = 0. _d 0
105     duIce (I,J,bi,bj) = 0. _d 0
106     dvIce (I,J,bi,bj) = 0. _d 0
107     uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
108     vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
109     ENDDO
110     ENDDO
111     C Compute things that do no change during the Newton iteration:
112     C sea-surface tilt and wind stress:
113     C FORCEX/Y0 - mass*(u/vIceNm1)/deltaT
114     DO J=1-Oly,sNy+Oly
115     DO I=1-Olx,sNx+Olx
116     FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
117     & + seaiceMassU(I,J,bi,bj)*uIceNm1(I,J,bi,bj)*recip_deltaT
118     FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
119     & + seaiceMassV(I,J,bi,bj)*vIceNm1(I,J,bi,bj)*recip_deltaT
120     ENDDO
121     ENDDO
122     ENDDO
123     ENDDO
124     C Start nonlinear Newton iteration: outer loop iteration
125     DO WHILE ( newtonIter.LT.SEAICEnewtonIterMax .AND.
126     & .NOT.JFNKconverged )
127     newtonIter = newtonIter + 1
128     C Compute initial residual F(u), (includes computation of global
129     C variables DWATN, zeta, and eta)
130     CALL SEAICE_CALC_RESIDUAL(
131     I uIce, vIce,
132     O uIceRes, vIceRes,
133     I newtonIter, 0, myTime, myIter, myThid )
134     C local copies of precomputed coefficients that are to stay
135     C constant for the preconditioner
136     DO bj=myByLo(myThid),myByHi(myThid)
137     DO bi=myBxLo(myThid),myBxHi(myThid)
138     DO j=1-Oly,sNy+Oly
139     DO i=1-Olx,sNx+Olx
140     zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
141     etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
142     dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
143     ENDDO
144     ENDDO
145     ENDDO
146     ENDDO
147     C
148     DO bj=myByLo(myThid),myByHi(myThid)
149     DO bi=myBxLo(myThid),myBxHi(myThid)
150     JFNKresidualTile(bi,bj) = 0. _d 0
151     DO J=1,sNy
152     DO I=1,sNx
153     #ifdef CG2D_SINGLECPU_SUM
154     JFNKlocalBuf(I,J,bi,bj) =
155     #else
156     JFNKresidualTile(bi,bj) = JFNKresidualTile(bi,bj) +
157     #endif
158     & uIceRes(I,J,bi,bj)*uIceRes(I,J,bi,bj) +
159     & vIceRes(I,J,bi,bj)*vIceRes(I,J,bi,bj)
160     ENDDO
161     ENDDO
162     ENDDO
163     ENDDO
164     JFNKresidual = 0. _d 0
165     #ifdef CG2D_SINGLECPU_SUM
166     CALL GLOBAL_SUM_SINGLECPU_RL(
167     & JFNKlocalBuf,JFNKresidual, 0, 0, myThid)
168     #else
169     CALL GLOBAL_SUM_TILE_RL( JFNKresidualTile,JFNKresidual,myThid )
170     #endif
171     JFNKresidual = SQRT(JFNKresidual)
172     C compute convergence criterion for linear preconditioned FGMRES
173     JFNKgamma_lin = JFNKgamma_lin_max
174     IF ( newtonIter.GT.1.AND.newtonIter.LE.100
175     & .AND.JFNKresidual.LT.JFNKres_t ) THEN
176     C Eisenstat, 1996, equ.(2.6)
177     phi_e = 1. _d 0
178     alp_e = 1. _d 0
179     JFNKgamma_lin = phi_e*( JFNKresidual/JFNKresidualKm1 )**alp_e
180     JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
181     JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
182     ENDIF
183     C save the residual for the next iteration
184     JFNKresidualKm1 = JFNKresidual
185     C
186     C The Krylov iteration using FGMRES, the preconditioner is LSOR
187     C for now. The code is adapted from SEAICE_LSR, but heavily stripped
188     C down.
189     C krylovIter is mapped into "its" in seaice_fgmres and is incremented
190     C in that routine
191     krylovIter = 0
192     iCode = 0
193     IF ( debugLevel.GE.debLevA ) THEN
194     WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
195     & ' S/R SEAICE_JFNK: newtonIter,',
196     & ' total newtonIter, JFNKgamma_lin, initial norm = ',
197     & newtonIter, SEAICEnewtonIterMax*myIter+newtonIter,
198     & JFNKgamma_lin, JFNKresidual
199     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
200     & SQUEEZE_RIGHT, myThid )
201     ENDIF
202     C
203     JFNKconverged = JFNKresidual.LT.JFNKtol
204     C
205     C do Krylov loop only if convergence is not reached
206     C
207     IF ( .NOT.JFNKconverged ) THEN
208     C
209     C start Krylov iteration (FGMRES)
210     C
211     krylovConverged = .FALSE.
212     FGMRESeps = JFNKgamma_lin * JFNKresidual
213     DO WHILE ( .NOT.krylovConverged )
214     C solution vector sol = du/vIce
215     C residual vector (rhs) Fu = u/vIceRes
216     C output work vectors wk1, -> input work vector wk2
217     C
218     CALL EXCH_UV_XY_RL( uIceRes, vIceRes,.TRUE.,myThid)
219     CALL EXCH_UV_XY_RL( duIce, dvIce,.TRUE.,myThid)
220     CALL SEAICE_FGMRES_DRIVER(
221     I uIceRes, vIceRes,
222     U duIce, dvIce, iCode,
223     I FGMRESeps,
224     I newtonIter, krylovIter, myTime, myIter, myThid )
225     C FGMRES returns iCode either asking for an new preconditioned vector
226     C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
227     C iteration
228     IF (iCode.EQ.1) THEN
229     C Call preconditioner
230     CALL SEAICE_PRECONDITIONER(
231     U duIce, dvIce,
232     I zetaPre, etaPre, dwatPre,
233     I newtonIter, krylovIter, myTime, myIter, myThid )
234     ELSEIF (iCode.GE.2) THEN
235     C Compute Jacobian times vector
236     CALL SEAICE_JACVEC(
237     I uIce, vIce, uIceRes, vIceRes,
238     U duIce, dvIce,
239     I newtonIter, krylovIter, myTime, myIter, myThid )
240     ENDIF
241     krylovConverged = iCode.EQ.0
242     C End of Krylov iterate
243     ENDDO
244     totalKrylovIter = totalKrylovIter + krylovIter
245     C some output diagnostics
246     IF ( debugLevel.GE.debLevA ) THEN
247     WRITE(msgBuf,'(3(A,I6))')
248     & ' S/R SEAICE_JFNK: Newton iterate / total = ', newtonIter,
249     & ' / ', SEAICEnewtonIterMax*myIter+newtonIter,
250     & ', Nb. of FGMRES iterations = ', krylovIter
251     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
252     & SQUEEZE_RIGHT, myThid )
253     ENDIF
254     IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
255     krylovIterFail = krylovIterFail + 1
256     ENDIF
257     C Update linear solution vector and return to Newton iteration
258     DO bj=myByLo(myThid),myByHi(myThid)
259     DO bi=myBxLo(myThid),myBxHi(myThid)
260     DO J=1-Oly,sNy+Oly
261     DO I=1-Olx,sNx+Olx
262     uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+duIce(I,J,bi,bj)
263     vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+dvIce(I,J,bi,bj)
264     ENDDO
265     ENDDO
266     ENDDO
267     ENDDO
268     C Set the stopping criterion for the Newton iteration
269     IF ( newtonIter .EQ. 1 ) JFNKtol=JFNKgamma_nonlin*JFNKresidual
270     ENDIF
271     C end of Newton iterate
272     ENDDO
273     C some output diagnostics
274     IF ( debugLevel.GE.debLevA ) THEN
275     C Record failure
276     IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
277     newtonIterFail = newtonIterFail + 1
278     WRITE(msgBuf,'(A,I10)')
279     & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
280     & myIter
281     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
282     & SQUEEZE_RIGHT, myThid )
283     ENDIF
284     IF ( krylovIterFail .GT. 0 ) THEN
285     WRITE(msgBuf,'(A,I4,A,I10)')
286     & ' S/R SEAICE_JFNK: FGMRES did not converge ',
287     & krylovIterFail, ' times in timestep ', myIter
288     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
289     & SQUEEZE_RIGHT, myThid )
290     ENDIF
291     WRITE(msgBuf,'(A,I6)')
292     & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
293     & totalKrylovIter
294     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
295     & SQUEEZE_RIGHT, myThid )
296    
297     ENDIF
298    
299     #endif /* SEAICE_ALLOW_DYNAMICS and SEAICE_CGRID and SEAICE_ALLOW_JFNK */
300    
301     RETURN
302     END

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