[MITgcm-support] nonlinFreeSurf=4 casue flow field change a lot

[Chun-Yan Zhou]

Hi all,
I did two cases of the regional without and with nonlinFreeSurf=4.
The model has south and east boundary,driven by boundary u v velocity.
The result of case without  nonlinFreeSurf seems reasonable, with all the conditions stay same except adding nonlinFreeSurf =4, the result change a lot, especially the flow direction in the southeast corner of the model(see the picture attached).

Can anyone tell me where is the problem? Thanks a lot.

# ====================
# | Model parameters |
# ====================
#
# Continuous equation parameters
 &PARM01
 viscAh=1.E2,
 viscAz=1.E-3,
 no_slip_sides=.TRUE.,
 no_slip_bottom=.TRUE.,
 viscC2Smag=2.0,
 viscAhGridMax=0.5,
 implicitViscosity=.TRUE.,
 implicitDiffusion=.TRUE.,
 diffKhT=1.E2,
 diffKzT=1.E-3,
 diffKhS=0.E2,
 diffKzS=0.E-5,
 tAlpha=2.E-4,
 sBeta =0.,
 gravity=9.81,
 eosType='LINEAR',
 tempStepping=.FALSE.,
 saltStepping=.FALSE.,
 implicSurfPress=0.5,
 implicDiv2DFlow=0.5,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 readBinaryPrec=64,
 writeBinaryPrec=32,
 hFacMin=0.05,
 nonlinFreeSurf=4,
 hFacInf=0.2,
 hFacSup=2.,
 exactConserv=.TRUE.,
 &

# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=1000,
 cg2dTargetResidual=1.E-13,
 &

# Time stepping parameters
 &PARM03
 nIter0=0,
 nTimeSteps=21600,
 deltaT=20,
 deltaTtracer=20,
 cAdjFreq=0.,
 abEps=0.02,
 pChkptFreq=432000,
 chkptFreq=0.0,
#dumpFreq=7200.0,
 dumpFreq=43200,
#taveFreq=86400.0,
 monitorFreq=36000.,
# periodicExternalForcing=.TRUE.,
externForcingPeriod=2592000,
externForcingCycle=31104000,
 pickupStrictlyMatch=.FALSE.,
 &

# Gridding parameters
 &PARM04
#constant delZ= 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140., 140.,
#variable

 usingSphericalPolarGrid=.TRUE.,
 delX=174*0.0625,
 delY=226*0.0625,
 delZ=10*3.,10*7.,10*25.,5*100.,5*180.,
 ygOrigin=27.03125,
 xgOrigin=117.46875,
 &

# Input datasets
 &PARM05
bathyFile='topognew1.bin',
dragQFile='dragQFile.bin',
uVelInitFile='UVEL200201.bin',
vVelInitFile='VVEL200201.bin',
 &

# Open-boundaries
 &OBCS_PARM01
 OB_Ieast=226*-1,
 OB_Jsouth=174*1,
 useOBCSprescribe=.TRUE.,
 OBEuFile = 'ueast4.bin',
 OBSuFile = 'usouth4.bin',
 OBEvFile = 'veast4.bin',
 OBSvFile = 'vsouth4.bin',

 &


Chunyan Zhou
Division of Civil Engineering
School of Engineering, Physics and Mathematics
College of Art, Science and Engineering
Fulton Building,G19
University of Dundee
Dundee, UK DD1 4HN
Tel. 01382 385431


The University of Dundee is a registered Scottish Charity, No: SC015096
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