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

[Martin Losch]

The default boundary value for ETAN is zero. For the linear free surface, this value is not used, but for the non-linear free-surface it is, so that you specify ETAN=0 along with your u and v velocities. You might want to add ETAN boundary values that are consistent with your normal boundary velocities (say from integrating geostrophy deta/dx = f/g * v)

M.
On Sep 5, 2012, at 12:11 AM, Chun-Yan Zhou wrote:

> 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
> <average current run11-9 better iter=21600.jpg><nonlinfreesurf.jpg>_______________________________________________
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