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

[Killampalli Rajesh]

Hi Martin

Here, I've included the depths and model results where I'm experiencing
high velocities. As you mentioned, I've checked the volume flux that has
already been observed, but not at the open boundary; instead, I've checked
the estuary, where I experience higher velocities for an entire tidal
cycle, with the volume flux remaining constant during the ebb and flood
phases. Since the velocities are caused by topography and geometric
factors, adjusting the tidal height and velocity in this area is more
difficult, yet it is still tried. I lowered the input velocities by the
time tidal height are matched with observation in order to correct
amplitudes, however the velocities are too much.

Kind regards
K Rajesh



[image: Screenshot from 2024-05-23 11-13-55.png]














On Wed, May 15, 2024 at 7:51 PM 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>
> 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>
>> 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
>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20240523/153225b7/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screenshot from 2024-05-23 11-13-55.png
Type: image/png
Size: 659705 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20240523/153225b7/attachment-0001.png>