/[MITgcm]/MITgcm/pkg/seaice/seaice_jfnk.F
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revision 1.14 by mlosch, Fri Jan 4 15:48:09 2013 UTC revision 1.16 by mlosch, Thu Jan 17 08:51:15 2013 UTC
# Line 3  C $Name$ Line 3  C $Name$
3    
4  #include "SEAICE_OPTIONS.h"  #include "SEAICE_OPTIONS.h"
5    
6    C--  File seaice_jfnk.F: seaice jfnk dynamical solver S/R:
7    C--   Contents
8    C--   o SEAICE_JFNK
9    C--   o SEAICE_JFNK_UPDATE
10    
11  CBOP  CBOP
12  C     !ROUTINE: SEAICE_JFNK  C     !ROUTINE: SEAICE_JFNK
13  C     !INTERFACE:  C     !INTERFACE:
# Line 10  C     !INTERFACE: Line 15  C     !INTERFACE:
15    
16  C     !DESCRIPTION: \bv  C     !DESCRIPTION: \bv
17  C     *==========================================================*  C     *==========================================================*
18  C     | SUBROUTINE SEAICE_JFKF  C     | SUBROUTINE SEAICE_JFNK
19  C     | o Ice dynamics using a Jacobian-free Newton-Krylov solver  C     | o Ice dynamics using a Jacobian-free Newton-Krylov solver
20  C     |   following J.-F. Lemieux et al. Improving the numerical  C     |   following J.-F. Lemieux et al. Improving the numerical
21  C     |   convergence of viscous-plastic sea ice models with the  C     |   convergence of viscous-plastic sea ice models with the
# Line 55  C     !FUNCTIONS: Line 60  C     !FUNCTIONS:
60        LOGICAL  DIFFERENT_MULTIPLE        LOGICAL  DIFFERENT_MULTIPLE
61        EXTERNAL DIFFERENT_MULTIPLE        EXTERNAL DIFFERENT_MULTIPLE
62    
63    C     !LOCAL VARIABLES:
64    C     === Local variables ===
65  C     i,j,bi,bj :: loop indices  C     i,j,bi,bj :: loop indices
66        INTEGER i,j,bi,bj        INTEGER i,j,bi,bj
67  C     loop indices  C     loop indices
# Line 142  C     Start nonlinear Newton iteration: Line 149  C     Start nonlinear Newton iteration:
149         newtonIter = newtonIter + 1         newtonIter = newtonIter + 1
150  C     Compute initial residual F(u), (includes computation of global  C     Compute initial residual F(u), (includes computation of global
151  C     variables DWATN, zeta, and eta)  C     variables DWATN, zeta, and eta)
152         CALL SEAICE_CALC_RESIDUAL(         IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
153       I      uIce, vIce,       I      duIce, dvIce,
154       O      uIceRes, vIceRes,       U      uIce, vIce, JFNKresidual,
155       I      newtonIter, 0, myTime, myIter, myThid )       O      uIceRes, vIceRes,
156  C     probably not necessary, will be removed later:       I      newtonIter, myTime, myIter, myThid )
        CALL EXCH_UV_XY_RL( uIceRes, vIceRes,.TRUE.,myThid)  
157  C     local copies of precomputed coefficients that are to stay  C     local copies of precomputed coefficients that are to stay
158  C     constant for the preconditioner  C     constant for the preconditioner
159         DO bj=myByLo(myThid),myByHi(myThid)         DO bj=myByLo(myThid),myByHi(myThid)
# Line 162  C     constant for the preconditioner Line 168  C     constant for the preconditioner
168           ENDDO           ENDDO
169          ENDDO          ENDDO
170         ENDDO         ENDDO
 C     Important: Compute the norm of the residual using the same scalar  
 C     product that SEAICE_FGMRES does  
        CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)  
        CALL SEAICE_SCALPROD(  
      &      nVec,1,1,1,resTmp,resTmp,JFNKresidual,myThid)  
        JFNKresidual = SQRT(JFNKresidual)  
171  C     compute convergence criterion for linear preconditioned FGMRES  C     compute convergence criterion for linear preconditioned FGMRES
172         JFNKgamma_lin = JFNKgamma_lin_max         JFNKgamma_lin = JFNKgamma_lin_max
173         IF ( newtonIter.GT.1.AND.newtonIter.LE.100         IF ( newtonIter.GT.1.AND.newtonIter.LE.100
# Line 254  C     some output diagnostics Line 254  C     some output diagnostics
254          IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN          IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
255           krylovFails = krylovFails + 1           krylovFails = krylovFails + 1
256          ENDIF          ENDIF
257    C     Set the stopping criterion for the Newton iteration
258            IF ( newtonIter .EQ. 1 ) JFNKtol=JFNKgamma_nonlin*JFNKresidual
259  C     Update linear solution vector and return to Newton iteration  C     Update linear solution vector and return to Newton iteration
260    C     Do a linesearch if necessary, and compute a new residual.
261    C     Note that it should be possible to do the following operations
262    C     at the beginning of the Newton iteration, thereby saving us from
263    C     the extra call of seaice_jfnk_update, but unfortunately that
264    C     changes the results, so we leave the stuff here for now.
265            CALL SEAICE_JFNK_UPDATE(
266         I       duIce, dvIce,
267         U       uIce, vIce, JFNKresidual,
268         O       uIceRes, vIceRes,
269         I       newtonIter, myTime, myIter, myThid )
270    C     reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
271          DO bj=myByLo(myThid),myByHi(myThid)          DO bj=myByLo(myThid),myByHi(myThid)
272           DO bi=myBxLo(myThid),myBxHi(myThid)           DO bi=myBxLo(myThid),myBxHi(myThid)
273            DO J=1-Oly,sNy+Oly            DO J=1-Oly,sNy+Oly
274             DO I=1-Olx,sNx+Olx             DO I=1-Olx,sNx+Olx
             uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+duIce(I,J,bi,bj)  
             vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+dvIce(I,J,bi,bj)  
 C     reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver  
275              duIce(I,J,bi,bj)= 0. _d 0              duIce(I,J,bi,bj)= 0. _d 0
276              dvIce(I,J,bi,bj)= 0. _d 0              dvIce(I,J,bi,bj)= 0. _d 0
277             ENDDO             ENDDO
278            ENDDO            ENDDO
279           ENDDO           ENDDO
280          ENDDO          ENDDO
 C     Set the stopping criterion for the Newton iteration  
         IF ( newtonIter .EQ. 1 ) JFNKtol=JFNKgamma_nonlin*JFNKresidual  
281         ENDIF         ENDIF
282  C     end of Newton iterate  C     end of Newton iterate
283        ENDDO        ENDDO
# Line 384  C     Print more debugging information Line 392  C     Print more debugging information
392         _END_MASTER( myThid )         _END_MASTER( myThid )
393        ENDIF        ENDIF
394    
395          RETURN
396          END
397    
398    C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
399    CBOP
400    C     !ROUTINE: SEAICE_JFNK_UPDATE
401    C     !INTERFACE:
402    
403          SUBROUTINE SEAICE_JFNK_UPDATE(
404         I     duIce, dvIce,
405         U     uIce, vIce, JFNKresidual,
406         O     uIceRes, vIceRes,
407         I     newtonIter, myTime, myIter, myThid )
408    
409    C     !DESCRIPTION: \bv
410    C     *==========================================================*
411    C     | SUBROUTINE SEAICE_JFNK_UPDATE
412    C     | o Update velocities with incremental solutions of FGMRES
413    C     | o compute residual of updated solutions and do
414    C     | o linesearch:
415    C     |   reduce update until residual is smaller than previous
416    C     |   one (input)
417    C     *==========================================================*
418    C     | written by Martin Losch, Jan 2013
419    C     *==========================================================*
420    C     \ev
421    
422    C     !USES:
423          IMPLICIT NONE
424    
425    C     === Global variables ===
426    #include "SIZE.h"
427    #include "EEPARAMS.h"
428    #include "PARAMS.h"
429    #include "SEAICE_SIZE.h"
430    #include "SEAICE_PARAMS.h"
431    
432    C     !INPUT/OUTPUT PARAMETERS:
433    C     === Routine arguments ===
434    C     myTime :: Simulation time
435    C     myIter :: Simulation timestep number
436    C     myThid :: my Thread Id. number
437    C     newtonIter :: current iterate of Newton iteration
438          _RL     myTime
439          INTEGER myIter
440          INTEGER myThid
441          INTEGER newtonIter
442    C     JFNKresidual :: Residual at the beginning of the FGMRES iteration,
443    C                     changes with newtonIter (updated)
444          _RL     JFNKresidual
445    C     du/vIce   :: ice velocity increment to be added to u/vIce (input)
446          _RL duIce  (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
447          _RL dvIce  (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
448    C     u/vIce    :: ice velocity increment to be added to u/vIce (updated)
449          _RL uIce   (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
450          _RL vIce   (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
451    C     u/vIceRes :: residual of sea-ice momentum equations (output)
452          _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
453          _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
454    
455    C     !LOCAL VARIABLES:
456    C     === Local variables ===
457    C     i,j,bi,bj :: loop indices
458          INTEGER i,j,bi,bj
459          INTEGER l
460          _RL     resLoc, facLS
461          LOGICAL doLineSearch
462    C     nVec    :: size of the input vector(s)
463    C     vector version of the residuals
464          INTEGER nVec
465          PARAMETER ( nVec  = 2*sNx*sNy )
466          _RL resTmp (nVec,1,nSx,nSy)
467    C
468          CHARACTER*(MAX_LEN_MBUF) msgBuf
469    CEOP
470    
471    C     Initialise some local variables
472          l = 0
473          resLoc = JFNKresidual
474          facLS = 1. _d 0
475          doLineSearch = .TRUE.
476          DO WHILE ( doLineSearch )
477    C     Determine, if we need more iterations
478           doLineSearch = resLoc .GE. JFNKresidual
479    C     Limit the maximum number of iterations arbitrarily to four
480           doLineSearch = doLineSearch .AND. l .LE. 4
481    C     For the first iteration du/vIce = 0 and there will be no
482    C     improvement of the residual possible, so we do only the first
483    C     iteration
484           IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
485    C     Only start a linesearch after some Newton iterations
486           IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
487    C     Increment counter
488           l = l + 1
489    C     Create update
490           DO bj=myByLo(myThid),myByHi(myThid)
491            DO bi=myBxLo(myThid),myBxHi(myThid)
492             DO J=1-Oly,sNy+Oly
493              DO I=1-Olx,sNx+Olx
494               uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
495               vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
496              ENDDO
497             ENDDO
498            ENDDO
499           ENDDO
500    C     Compute current residual F(u), (includes re-computation of global
501    C     variables DWATN, zeta, and eta, i.e. they are different after this)
502           CALL SEAICE_CALC_RESIDUAL(
503         I      uIce, vIce,
504         O      uIceRes, vIceRes,
505         I      newtonIter, 0, myTime, myIter, myThid )
506    C     Important: Compute the norm of the residual using the same scalar
507    C     product that SEAICE_FGMRES does
508           CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
509           CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
510           resLoc = SQRT(resLoc)
511    C     some output diagnostics
512           IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
513            _BEGIN_MASTER( myThid )
514            WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
515         &       ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
516         &       'facLS, JFNKresidual, resLoc = ',
517         &        newtonIter, l, facLS, JFNKresidual, resLoc
518            CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
519         &       SQUEEZE_RIGHT, myThid )
520            _END_MASTER( myThid )
521           ENDIF
522    C     Get ready for the next iteration: after adding du/vIce in the first
523    C     iteration, we substract 0.5*du/vIce from u/vIce in the next
524    C     iterations, 0.25*du/vIce in the second, etc.
525           facLS = - 0.5 _d 0 * ABS(facLS)
526          ENDDO
527    C     This is the new residual
528          JFNKresidual = resLoc
529    
530  #endif /* SEAICE_ALLOW_DYNAMICS and SEAICE_CGRID and SEAICE_ALLOW_JFNK */  #endif /* SEAICE_ALLOW_DYNAMICS and SEAICE_CGRID and SEAICE_ALLOW_JFNK */
531    
532        RETURN        RETURN
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