[MITgcm-support] Does the value of the parameter "viscAh" have a limit? (ideal_2D_oce)

[Martin Losch]

Hi Yanhong,

the only reason I see here is that with a 10 times larger viscosity the free surface solver has more to do (although not clear why). Compare how many cg2d iterations you are doing between the different runs (grep for  “cg2d_iters” in your stdout) to find out.

Martin

> On 24. Jun 2020, at 02:51, 赖燕红 <yhlai at pku.edu.cn> wrote:
> 
> Hi,
> 
> When I tried to change the parameter "viscAh" from 12E5(its default value) to 12E6 when usind ideal_2D_oce case, for some reason the simulation proceeds extremely slowly, like it only simulates 5000 years after integrated for 48 hours, but normally it only needs a few hours to complete 10 thousand years simulation if we don't change "viscAh" to 12E6, do you know why or does the value of "viscAh" have a limit?
> 
> 
> Here's part of my data file:
> # Continuous equation parameters
>  &PARM01
>  tRef= 18.8, 16.3, 13.1, 10.4, 8.1, 6.0, 4.5,
>       3.4, 2.7, 2.2, 1.8, 1.5, 1.2, 1.0, 0.9,
>  sRef= 15*34.7,
>  cosPower=1.,
>  viscAr=1.E-3,
>  viscAh=12.E6,
>  no_slip_sides=.FALSE.,
>  no_slip_bottom=.TRUE.,
>  bottomDragLinear=1.E-3,
> #diffK4T=2.E12,
>  diffKhT=0.E3,
>  diffKrNrT=1.E-4, 14*1.E-5,
>  ivdc_kappa=100.,
>  implicitDiffusion=.TRUE.,
>  eosType='LINEAR',
>  tAlpha=2.E-4,
>  sBeta =0.E-4,
>  saltStepping=.FALSE.,
>  gravity=9.81,
>  rhonil=1035.,
>  implicitFreeSurface=.TRUE.,
>  exactConserv=.TRUE., 
>  staggerTimeStep=.TRUE.,  useCDscheme=.TRUE.,  readBinaryPrec=64,  tempAdvScheme=77,  usePickupBeforeC54=.TRUE.,  & # Elliptic solver parameters  &PARM02  cg2dMaxIters=1000, #cg2dTargetResidual=1.E-13,  cg2dTargetResWunit=1.E-17,  &
> ... 
> 
> Thanks in advance!
> 
> Yanhong
> 
> 
> 
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