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Revision 1.30 - (show annotations) (download)
Thu Jan 28 12:54:12 2016 UTC (9 years, 5 months ago) by mlosch
Branch: MAIN
CVS Tags: checkpoint66g, checkpoint66f, checkpoint66e, checkpoint66d, checkpoint66c, checkpoint66b, checkpoint66a, checkpoint66h, checkpoint65z, checkpoint65x, checkpoint65y, checkpoint65v, checkpoint65w, checkpoint65t, checkpoint65u
Changes since 1.29: +19 -12 lines
unify iteration parameters for implicit solvers (JFNK and Picard)
    SEAICEnonLinIterMax replaces SEAICEnewtonIterMax/NPSEUDOTIMESTEPS
    SEAICElinearIterMax replaces SEAICEkrylovIterMax/SOLV_MAX_ITER
    SEAICEpreLinIterMax replaces SOLV_MAX_ITER in preconditioner
    SEAICEpreNL_IterMax replaces NPSEUDOTIMESTEPS in preconditioner
    SEAICEnonLinTol     replaces JFNKgamma_nonlin
old parameters are retired (setting them will lead to a STOP)

1 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.29 2016/01/27 14:03:34 mlosch Exp $
2 C $Name: $
3
4 #include "SEAICE_OPTIONS.h"
5 #ifdef ALLOW_AUTODIFF
6 # include "AUTODIFF_OPTIONS.h"
7 #endif
8
9 C-- File seaice_jfnk.F: seaice jfnk dynamical solver S/R:
10 C-- Contents
11 C-- o SEAICE_JFNK
12 C-- o SEAICE_JFNK_UPDATE
13
14 CBOP
15 C !ROUTINE: SEAICE_JFNK
16 C !INTERFACE:
17 SUBROUTINE SEAICE_JFNK( myTime, myIter, myThid )
18
19 C !DESCRIPTION: \bv
20 C *==========================================================*
21 C | SUBROUTINE SEAICE_JFNK
22 C | o Ice dynamics using a Jacobian-free Newton-Krylov solver
23 C | following J.-F. Lemieux et al. Improving the numerical
24 C | convergence of viscous-plastic sea ice models with the
25 C | Jacobian-free Newton-Krylov method. J. Comp. Phys. 229,
26 C | 2840-2852 (2010).
27 C | o The logic follows JFs code.
28 C *==========================================================*
29 C | written by Martin Losch, Oct 2012
30 C *==========================================================*
31 C \ev
32
33 C !USES:
34 IMPLICIT NONE
35
36 C === Global variables ===
37 #include "SIZE.h"
38 #include "EEPARAMS.h"
39 #include "PARAMS.h"
40 #include "DYNVARS.h"
41 #include "GRID.h"
42 #include "SEAICE_SIZE.h"
43 #include "SEAICE_PARAMS.h"
44 #include "SEAICE.h"
45
46 #ifdef ALLOW_AUTODIFF_TAMC
47 # include "tamc.h"
48 #endif
49
50 C !INPUT/OUTPUT PARAMETERS:
51 C === Routine arguments ===
52 C myTime :: Simulation time
53 C myIter :: Simulation timestep number
54 C myThid :: my Thread Id. number
55 _RL myTime
56 INTEGER myIter
57 INTEGER myThid
58
59 #ifdef SEAICE_ALLOW_JFNK
60 C !FUNCTIONS:
61 LOGICAL DIFFERENT_MULTIPLE
62 EXTERNAL DIFFERENT_MULTIPLE
63
64 C !LOCAL VARIABLES:
65 C === Local variables ===
66 C i,j,bi,bj :: loop indices
67 INTEGER i,j,bi,bj
68 C loop indices
69 INTEGER newtonIter
70 INTEGER krylovIter, krylovFails
71 INTEGER totalKrylovItersLoc, totalNewtonItersLoc
72 C FGMRES parameters
73 C im :: size of Krylov space
74 C ifgmres :: interation counter
75 INTEGER im
76 PARAMETER ( im = 50 )
77 INTEGER ifgmres
78 C FGMRES flag that determines amount of output messages of fgmres
79 INTEGER iOutFGMRES
80 C FGMRES flag that indicates what fgmres wants us to do next
81 INTEGER iCode
82 _RL JFNKresidual
83 _RL JFNKresidualKm1
84 C parameters to compute convergence criterion
85 _RL JFNKgamma_lin
86 _RL FGMRESeps
87 _RL JFNKtol
88 C backward differences extrapolation factors
89 _RL bdfFac, bdfAlpha
90 C
91 _RL recip_deltaT
92 LOGICAL JFNKconverged, krylovConverged
93 LOGICAL writeNow
94 CHARACTER*(MAX_LEN_MBUF) msgBuf
95
96 C u/vIceRes :: residual of sea-ice momentum equations
97 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
98 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
99 C extra time level required for backward difference time stepping
100 _RL duIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
101 _RL dvIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
102 C du/vIce :: ice velocity increment to be added to u/vIce
103 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
104 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
105 C precomputed (= constant per Newton iteration) versions of
106 C zeta, eta, and DWATN, press
107 _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
108 _RL zetaZPre(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
109 _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
110 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
111 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
112 C work arrays
113 _RL rhs(nVec,nSx,nSy), sol(nVec,nSx,nSy)
114 _RL vv(nVec,im+1,nSx,nSy), w(nVec,im,nSx,nSy)
115 _RL wk1(nVec,nSx,nSy), wk2(nVec,nSx,nSy)
116 CEOP
117
118 C Initialise
119 newtonIter = 0
120 krylovFails = 0
121 totalKrylovItersLoc = 0
122 JFNKconverged = .FALSE.
123 JFNKtol = 0. _d 0
124 JFNKresidual = 0. _d 0
125 JFNKresidualKm1 = 0. _d 0
126 FGMRESeps = 0. _d 0
127 recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
128
129 iOutFGMRES=0
130 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
131 IF ( debugLevel.GE.debLevC .AND.
132 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
133 & iOutFGMRES=1
134
135 C backward difference extrapolation factors
136 bdfFac = 0. _d 0
137 IF ( SEAICEuseBDF2 ) THEN
138 IF ( myIter.EQ.nIter0 .AND. SEAICEmomStartBDF.EQ.0 ) THEN
139 bdfFac = 0. _d 0
140 ELSE
141 bdfFac = 0.5 _d 0
142 ENDIF
143 ENDIF
144 bdfAlpha = 1. _d 0 + bdfFac
145
146 DO bj=myByLo(myThid),myByHi(myThid)
147 DO bi=myBxLo(myThid),myBxHi(myThid)
148 DO J=1-OLy,sNy+OLy
149 DO I=1-OLx,sNx+OLx
150 uIceRes(I,J,bi,bj) = 0. _d 0
151 vIceRes(I,J,bi,bj) = 0. _d 0
152 duIce (I,J,bi,bj) = 0. _d 0
153 dvIce (I,J,bi,bj) = 0. _d 0
154 ENDDO
155 ENDDO
156 C cycle ice velocities
157 DO J=1-OLy,sNy+OLy
158 DO I=1-OLx,sNx+OLx
159 duIcNm1(I,J,bi,bj) = uIce(I,J,bi,bj) * bdfAlpha
160 & + ( uIce(I,J,bi,bj) - uIceNm1(I,J,bi,bj) ) * bdfFac
161 dvIcNm1(I,J,bi,bj) = vIce(I,J,bi,bj) * bdfAlpha
162 & + ( vIce(I,J,bi,bj) - vIceNm1(I,J,bi,bj) ) * bdfFac
163 uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
164 vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
165 ENDDO
166 ENDDO
167 C As long as IMEX is not properly implemented leave this commented out
168 CML IF ( .NOT.SEAICEuseIMEX ) THEN
169 C Compute things that do no change during the Newton iteration:
170 C sea-surface tilt and wind stress:
171 C FORCEX/Y0 - mass*(1.5*u/vIceNm1+0.5*(u/vIceNm1-u/vIceNm2))/deltaT
172 DO J=1-OLy,sNy+OLy
173 DO I=1-OLx,sNx+OLx
174 FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
175 & + seaiceMassU(I,J,bi,bj)*duIcNm1(I,J,bi,bj)*recip_deltaT
176 FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
177 & + seaiceMassV(I,J,bi,bj)*dvIcNm1(I,J,bi,bj)*recip_deltaT
178 ENDDO
179 ENDDO
180 CML ENDIF
181 ENDDO
182 ENDDO
183 C Start nonlinear Newton iteration: outer loop iteration
184 DO WHILE ( newtonIter.LT.SEAICEnonLinIterMax .AND.
185 & .NOT.JFNKconverged )
186 newtonIter = newtonIter + 1
187 C Compute initial residual F(u), (includes computation of global
188 C variables DWATN, zeta, and eta)
189 IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
190 I duIce, dvIce,
191 U uIce, vIce, JFNKresidual,
192 O uIceRes, vIceRes,
193 I newtonIter, myTime, myIter, myThid )
194 C local copies of precomputed coefficients that are to stay
195 C constant for the preconditioner
196 DO bj=myByLo(myThid),myByHi(myThid)
197 DO bi=myBxLo(myThid),myBxHi(myThid)
198 DO j=1-OLy,sNy+OLy
199 DO i=1-OLx,sNx+OLx
200 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
201 zetaZPre(I,J,bi,bj)= zetaZ(I,J,bi,bj)
202 etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
203 etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
204 dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
205 ENDDO
206 ENDDO
207 ENDDO
208 ENDDO
209 C compute convergence criterion for linear preconditioned FGMRES
210 JFNKgamma_lin = JFNKgamma_lin_max
211 IF ( newtonIter.GT.1.AND.newtonIter.LE.SEAICE_JFNK_tolIter
212 & .AND.JFNKresidual.LT.JFNKres_t ) THEN
213 C Eisenstat and Walker (1996), eq.(2.6)
214 JFNKgamma_lin = SEAICE_JFNKphi
215 & *( JFNKresidual/JFNKresidualKm1 )**SEAICE_JFNKalpha
216 JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
217 JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
218 ENDIF
219 C save the residual for the next iteration
220 JFNKresidualKm1 = JFNKresidual
221
222 C The Krylov iteration using FGMRES, the preconditioner is LSOR
223 C for now. The code is adapted from SEAICE_LSR, but heavily stripped
224 C down.
225 C krylovIter is mapped into "its" in seaice_fgmres and is incremented
226 C in that routine
227 krylovIter = 0
228 iCode = 0
229
230 JFNKconverged = JFNKresidual.LT.JFNKtol
231
232 C do Krylov loop only if convergence is not reached
233
234 IF ( .NOT.JFNKconverged ) THEN
235
236 C start Krylov iteration (FGMRES)
237
238 krylovConverged = .FALSE.
239 FGMRESeps = JFNKgamma_lin * JFNKresidual
240 C map first guess sol; it is zero because the solution is a correction
241 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,sol,.TRUE.,myThid)
242 C map rhs and change its sign because we are solving J*u = -F
243 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,rhs,.TRUE.,myThid)
244 DO bj=myByLo(myThid),myByHi(myThid)
245 DO bi=myBxLo(myThid),myBxHi(myThid)
246 DO j=1,nVec
247 rhs(j,bi,bj) = - rhs(j,bi,bj)
248 ENDDO
249 ENDDO
250 ENDDO
251 DO WHILE ( .NOT.krylovConverged )
252 C solution vector sol = du/vIce
253 C residual vector (rhs) Fu = u/vIceRes
254 C output work vectors wk1, -> input work vector wk2
255
256 C map preconditioner results or Jacobian times vector,
257 C stored in du/vIce to wk2, for iCode=0, wk2 is set to zero,
258 C because du/vIce = 0
259 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,wk2,.TRUE.,myThid)
260 C
261 CALL SEAICE_FGMRES (nVec,im,rhs,sol,ifgmres,krylovIter,
262 U vv,w,wk1,wk2,
263 I FGMRESeps,SEAICElinearIterMax,iOutFGMRES,
264 U iCode,
265 I myThid)
266 C
267 IF ( iCode .EQ. 0 ) THEN
268 C map sol(ution) vector to du/vIce
269 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,sol,.FALSE.,myThid)
270 ELSE
271 C map work vector to du/vIce to either compute a preconditioner
272 C solution (wk1=rhs) or a Jacobian times wk1
273 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,wk1,.FALSE.,myThid)
274 ENDIF
275 C Fill overlaps in updated fields
276 CALL EXCH_UV_XY_RL( duIce, dvIce,.TRUE.,myThid)
277 C FGMRES returns iCode either asking for an new preconditioned vector
278 C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
279 C iteration
280 IF (iCode.EQ.1) THEN
281 C Call preconditioner
282 IF ( SEAICEpreconLinIter .GT. 0 )
283 & CALL SEAICE_PRECONDITIONER(
284 U duIce, dvIce,
285 I zetaPre, etaPre, etaZpre, zetaZpre, dwatPre,
286 I newtonIter, krylovIter, myTime, myIter, myThid )
287 ELSEIF (iCode.GE.2) THEN
288 C Compute Jacobian times vector
289 CALL SEAICE_JACVEC(
290 I uIce, vIce, uIceRes, vIceRes,
291 U duIce, dvIce,
292 I newtonIter, krylovIter, myTime, myIter, myThid )
293 ENDIF
294 krylovConverged = iCode.EQ.0
295 C End of Krylov iterate
296 ENDDO
297 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
298 C some output diagnostics
299 IF ( debugLevel.GE.debLevA ) THEN
300 _BEGIN_MASTER( myThid )
301 totalNewtonItersLoc =
302 & SEAICEnonLinIterMax*(myIter-nIter0)+newtonIter
303 WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
304 & ' S/R SEAICE_JFNK: Newton iterate / total, ',
305 & 'JFNKgamma_lin, initial norm = ',
306 & newtonIter, totalNewtonItersLoc,
307 & JFNKgamma_lin,JFNKresidual
308 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
309 & SQUEEZE_RIGHT, myThid )
310 WRITE(msgBuf,'(3(A,I6))')
311 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
312 & ' / ', totalNewtonItersLoc,
313 & ', Nb. of FGMRES iterations = ', krylovIter
314 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
315 & SQUEEZE_RIGHT, myThid )
316 _END_MASTER( myThid )
317 ENDIF
318 IF ( krylovIter.EQ.SEAICElinearIterMax ) THEN
319 krylovFails = krylovFails + 1
320 ENDIF
321 C Set the stopping criterion for the Newton iteration and the
322 C criterion for the transition from accurate to approximate FGMRES
323 IF ( newtonIter .EQ. 1 ) THEN
324 JFNKtol=SEAICEnonLinTol*JFNKresidual
325 IF ( JFNKres_tFac .NE. UNSET_RL )
326 & JFNKres_t = JFNKresidual * JFNKres_tFac
327 ENDIF
328 C Update linear solution vector and return to Newton iteration
329 C Do a linesearch if necessary, and compute a new residual.
330 C Note that it should be possible to do the following operations
331 C at the beginning of the Newton iteration, thereby saving us from
332 C the extra call of seaice_jfnk_update, but unfortunately that
333 C changes the results, so we leave the stuff here for now.
334 CALL SEAICE_JFNK_UPDATE(
335 I duIce, dvIce,
336 U uIce, vIce, JFNKresidual,
337 O uIceRes, vIceRes,
338 I newtonIter, myTime, myIter, myThid )
339 C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
340 DO bj=myByLo(myThid),myByHi(myThid)
341 DO bi=myBxLo(myThid),myBxHi(myThid)
342 DO J=1-OLy,sNy+OLy
343 DO I=1-OLx,sNx+OLx
344 duIce(I,J,bi,bj)= 0. _d 0
345 dvIce(I,J,bi,bj)= 0. _d 0
346 ENDDO
347 ENDDO
348 ENDDO
349 ENDDO
350 ENDIF
351 C end of Newton iterate
352 ENDDO
353
354 C-- Output diagnostics
355
356 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
357 C Count iterations
358 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
359 totalNewtonIters = totalNewtonIters + newtonIter
360 totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
361 C Record failure
362 totalKrylovFails = totalKrylovFails + krylovFails
363 IF ( newtonIter .EQ. SEAICEnonLinIterMax ) THEN
364 totalNewtonFails = totalNewtonFails + 1
365 ENDIF
366 ENDIF
367 C Decide whether it is time to dump and reset the counter
368 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
369 & myTime+deltaTClock, deltaTClock)
370 #ifdef ALLOW_CAL
371 IF ( useCAL ) THEN
372 CALL CAL_TIME2DUMP(
373 I zeroRL, SEAICE_monFreq, deltaTClock,
374 U writeNow,
375 I myTime+deltaTclock, myIter+1, myThid )
376 ENDIF
377 #endif
378 IF ( writeNow ) THEN
379 _BEGIN_MASTER( myThid )
380 WRITE(msgBuf,'(A)')
381 &' // ======================================================='
382 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
383 & SQUEEZE_RIGHT, myThid )
384 WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
385 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
386 & SQUEEZE_RIGHT, myThid )
387 WRITE(msgBuf,'(A)')
388 &' // ======================================================='
389 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
390 & SQUEEZE_RIGHT, myThid )
391 WRITE(msgBuf,'(A,I10)')
392 & ' %JFNK_MON: time step = ', myIter+1
393 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
394 & SQUEEZE_RIGHT, myThid )
395 WRITE(msgBuf,'(A,I10)')
396 & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
397 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
398 & SQUEEZE_RIGHT, myThid )
399 WRITE(msgBuf,'(A,I10)')
400 & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
401 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
402 & SQUEEZE_RIGHT, myThid )
403 WRITE(msgBuf,'(A,I10)')
404 & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
405 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
406 & SQUEEZE_RIGHT, myThid )
407 WRITE(msgBuf,'(A,I10)')
408 & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
409 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
410 & SQUEEZE_RIGHT, myThid )
411 WRITE(msgBuf,'(A,I10)')
412 & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
413 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
414 & SQUEEZE_RIGHT, myThid )
415 WRITE(msgBuf,'(A)')
416 &' // ======================================================='
417 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
418 & SQUEEZE_RIGHT, myThid )
419 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
420 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
421 & SQUEEZE_RIGHT, myThid )
422 WRITE(msgBuf,'(A)')
423 &' // ======================================================='
424 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
425 & SQUEEZE_RIGHT, myThid )
426 _END_MASTER( myThid )
427 C reset and start again
428 totalJFNKtimeSteps = 0
429 totalNewtonIters = 0
430 totalKrylovIters = 0
431 totalKrylovFails = 0
432 totalNewtonFails = 0
433 ENDIF
434
435 C Print more debugging information
436 IF ( debugLevel.GE.debLevA ) THEN
437 IF ( newtonIter .EQ. SEAICEnonLinIterMax ) THEN
438 _BEGIN_MASTER( myThid )
439 WRITE(msgBuf,'(A,I10)')
440 & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
441 & myIter+1
442 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
443 & SQUEEZE_RIGHT, myThid )
444 _END_MASTER( myThid )
445 ENDIF
446 IF ( krylovFails .GT. 0 ) THEN
447 _BEGIN_MASTER( myThid )
448 WRITE(msgBuf,'(A,I4,A,I10)')
449 & ' S/R SEAICE_JFNK: FGMRES did not converge ',
450 & krylovFails, ' times in timestep ', myIter+1
451 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
452 & SQUEEZE_RIGHT, myThid )
453 _END_MASTER( myThid )
454 ENDIF
455 _BEGIN_MASTER( myThid )
456 WRITE(msgBuf,'(A,I6,A,I10)')
457 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
458 & totalKrylovItersLoc, ' in timestep ', myIter+1
459 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
460 & SQUEEZE_RIGHT, myThid )
461 _END_MASTER( myThid )
462 ENDIF
463
464 RETURN
465 END
466
467 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
468 CBOP
469 C !ROUTINE: SEAICE_JFNK_UPDATE
470 C !INTERFACE:
471
472 SUBROUTINE SEAICE_JFNK_UPDATE(
473 I duIce, dvIce,
474 U uIce, vIce, JFNKresidual,
475 O uIceRes, vIceRes,
476 I newtonIter, myTime, myIter, myThid )
477
478 C !DESCRIPTION: \bv
479 C *==========================================================*
480 C | SUBROUTINE SEAICE_JFNK_UPDATE
481 C | o Update velocities with incremental solutions of FGMRES
482 C | o compute residual of updated solutions and do
483 C | o linesearch:
484 C | reduce update until residual is smaller than previous
485 C | one (input)
486 C *==========================================================*
487 C | written by Martin Losch, Jan 2013
488 C *==========================================================*
489 C \ev
490
491 C !USES:
492 IMPLICIT NONE
493
494 C === Global variables ===
495 #include "SIZE.h"
496 #include "EEPARAMS.h"
497 #include "PARAMS.h"
498 #include "SEAICE_SIZE.h"
499 #include "SEAICE_PARAMS.h"
500
501 C !INPUT/OUTPUT PARAMETERS:
502 C === Routine arguments ===
503 C myTime :: Simulation time
504 C myIter :: Simulation timestep number
505 C myThid :: my Thread Id. number
506 C newtonIter :: current iterate of Newton iteration
507 _RL myTime
508 INTEGER myIter
509 INTEGER myThid
510 INTEGER newtonIter
511 C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
512 C changes with newtonIter (updated)
513 _RL JFNKresidual
514 C du/vIce :: ice velocity increment to be added to u/vIce (input)
515 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
516 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
517 C u/vIce :: ice velocity increment to be added to u/vIce (updated)
518 _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
519 _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
520 C u/vIceRes :: residual of sea-ice momentum equations (output)
521 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
522 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
523
524 C !LOCAL VARIABLES:
525 C === Local variables ===
526 C i,j,bi,bj :: loop indices
527 INTEGER i,j,bi,bj
528 INTEGER l
529 _RL resLoc, facLS
530 LOGICAL doLineSearch
531 C nVec :: size of the input vector(s)
532 C resTmp :: vector version of the residuals
533 INTEGER nVec
534 PARAMETER ( nVec = 2*sNx*sNy )
535 _RL resTmp (nVec,1,nSx,nSy)
536
537 CHARACTER*(MAX_LEN_MBUF) msgBuf
538 CEOP
539
540 C Initialise some local variables
541 l = 0
542 resLoc = JFNKresidual
543 facLS = 1. _d 0
544 doLineSearch = .TRUE.
545 DO WHILE ( doLineSearch )
546 C Create update
547 DO bj=myByLo(myThid),myByHi(myThid)
548 DO bi=myBxLo(myThid),myBxHi(myThid)
549 DO J=1-OLy,sNy+OLy
550 DO I=1-OLx,sNx+OLx
551 uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
552 vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
553 ENDDO
554 ENDDO
555 ENDDO
556 ENDDO
557 C Compute current residual F(u), (includes re-computation of global
558 C variables DWATN, zeta, and eta, i.e. they are different after this)
559 CALL SEAICE_CALC_RESIDUAL(
560 I uIce, vIce,
561 O uIceRes, vIceRes,
562 I newtonIter, 0, myTime, myIter, myThid )
563 C Important: Compute the norm of the residual using the same scalar
564 C product that SEAICE_FGMRES does
565 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
566 CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
567 resLoc = SQRT(resLoc)
568 C Determine, if we need more iterations
569 doLineSearch = resLoc .GE. JFNKresidual
570 C Limit the maximum number of iterations arbitrarily to four
571 doLineSearch = doLineSearch .AND. l .LT. 4
572 C For the first iteration du/vIce = 0 and there will be no
573 C improvement of the residual possible, so we do only the first
574 C iteration
575 IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
576 C Only start a linesearch after some Newton iterations
577 IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
578 C Increment counter
579 l = l + 1
580 C some output diagnostics
581 IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
582 _BEGIN_MASTER( myThid )
583 WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
584 & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
585 & 'facLS, JFNKresidual, resLoc = ',
586 & newtonIter, l, facLS, JFNKresidual, resLoc
587 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
588 & SQUEEZE_RIGHT, myThid )
589 _END_MASTER( myThid )
590 ENDIF
591 C Get ready for the next iteration: after adding du/vIce in the first
592 C iteration, we substract 0.5*du/vIce from u/vIce in the next
593 C iterations, 0.25*du/vIce in the second, etc.
594 facLS = - 0.5 _d 0 * ABS(facLS)
595 ENDDO
596 C This is the new residual
597 JFNKresidual = resLoc
598
599 #endif /* SEAICE_ALLOW_JFNK */
600
601 RETURN
602 END

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