[MITgcm-support] time step problem for cs510?

[Jean-Michel Campin]

Hi Zhaomin,

May be a little bit of 'context' type information might help
(type of set-up, type of problem you want to addess, ...).
And also some numerical details about your set-up could 
also be useful (in general, the usefulness of the response you
could expect from this list is largely function of the 
how precise the problem is described).

Cheers,
Jean-Michel

On Wed, Aug 24, 2011 at 03:19:04PM +0100, Wang, Zhaomin wrote:
> Hi,
> 
> We have one run probably stopped by numerical instability. We used cube sphere 510 configuration, and initially used deltaT=1200. When the run was stopped, we reduced deltaT to 600. When the one was stopped again, we used deltaT=300. However, the run was also stopped even for this very small time step. We did not try to reduce deltaT further, because the instability may not be caused by a too large time step.  We got the following error message:
> 
> ***********************
> WARNING: r*FacW < hFacInf at       8 pts : bi,bj,Thid,Iter=   1   1   1   1694086
>  e.g. at i,j=  24  24 ; rStarFac,H,eta =       NaN  4.281800E+02           NaN -1.058899E+00
> STOP in CALC_R_STAR : too SMALL rStarFacW !
> WARNING: r*FacS < hFacInf at       8 pts : bi,bj,Thid,Iter=   1   1   1   1694086
>  e.g. at i,j=  23  25 ; rStarFac,H,eta =       NaN  4.281800E+02           NaN -8.253981E-01
> STOP in CALC_R_STAR : too SMALL rStarFacS !
> WARNING: r*FacC < hFacInf at       5 pts : bi,bj,Thid,Iter=   1   1   1   1694086
>  e.g. at i,j=  23  24 ; rStarFac,H,eta =       NaN  4.281800E+02           NaN
> STOP in CALC_R_STAR : too SMALL rStarFacC !
> ********************
> 
> Thanks.
> 
> Zhaomin
> 
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