[MITgcm-support] Problem: Extreme Tidal Currents in the Simulation at Narrow Channels.

[Martin Losch]

Hi,

there’s not much I can say. 

Without knowing the details of the problem (details of bathymetry, flow field, where exactly is it too high), I can only speculate: 1. your open boundary values for velocity are too high, 2. your topography is too shallow or narrow to lead to a funnel where tidal flows amplify due to geometric conditions.

Maybe you can do an analysis of of how the volumeflux changes per section going away from the open boundary and see if there is volume produced (probably not).

Martin

> On 15. May 2024, at 16:21, Killampalli Rajesh <rajesh70530 at gmail.com> wrote:
> 
> Dear Martin 
> 
> Thank you for your response. I repent for having missed it. My model domain is the Coringa Estuary on India's east coast. where several creeks/channels meet to the estuary is my model area. I'm making a high-resolution tide model with a horizontal resolution of 100m for this domain. Include name list and model code files. Please see links 1 and 2. In link 2 I followed the method to preprocess the baroclinic tidal current where Data from TPXO7.2 was utilized to produce boundary conditions (OBEam, OBEph) amplitude and phase. 
> 
> http://wwwcvs.mitgcm.org/viewvc/MITgcm/MITgcm_contrib/tides/?diff_format=s&sortby=log&pathrev=HEAD
> https://github.com/RajeshKillampalli/MITgcm_tidesetup_02/tree/main
> 
> On Tue, May 14, 2024 at 7:02 PM Killampalli Rajesh <rajesh70530 at gmail.com <mailto:rajesh70530 at gmail.com>> wrote:
>> Dear MITgcm community
>> 
>> I have added additional points to the earlier post "Extreme tidal currents in the simulation at narrow channels".Model mesh resolution is 100 metres. I'm attempting to resolve this issue by adjusting the bottomdragliner coefficient, which was previously set to 0.002. When it increases to 0.006, the model blows up and writes NaNs. For 0.005, the model may run, but the velocities are not reduced as expected, and less variance is recognised. Currently, the maximum channel flow was 1.25m/s; after modifying to 0.005, it was 1.21m/s redused. and I experimented with ViscAh from 10 to 100, but no substantial difference was seen. Can someone advise how to solve this?          
>> 
>> Best Regards
>> Killampalli Rajesh
>> 
>> On Wed, May 8, 2024 at 6:56 PM Killampalli Rajesh <rajesh70530 at gmail.com <mailto:rajesh70530 at gmail.com>> wrote:
>>> Dear MITgcm community 
>>> 
>>> Thank you for your assistance; I'm modelling tidal circulation in the lagoon, which is connected to the coastal seas.The research region includes lagoon and coastal waterways. The boundary conditions include baroclinic tidal currents at open boundaries in data.obcs, OBEam, and OBEph only on the eastern border, and OBCS_Tides specified in the model. The model results is verified using tidal heights with the tide gauge data, however the tidal currents are exaggerated. In example, the model findings suggest extremely strong tidal currents at the mouth/channel, which contradicts reality.
>>> 
>>> Best Regards
>>> Killampalli Rajesh
>>> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20240521/1c630743/attachment-0001.html>