[RegCNET] Simulation stops due to CFL violation in-spite of decreasing dt

[Enrique Pazos]

Hi,

you could give it a try, I learned that if you have steep gradients in your
topography, the non-hydrostatic core can help dealing with them.

Best,

e.

On Wed, Aug 9, 2017 at 11:07 PM, SUDIPTA GHOSH <sudiptaghosh006 at gmail.com>
wrote:

> Hello Enrique,
>
> Firstly thank you for the suggestion.
>
> But my resolution is ds=25km, 50km. According to the user guide the model
> should work in hydrostatic core above ds=20km. Can you please help in the
> fact?
>
> On Thu, Aug 10, 2017 at 2:09 AM, Enrique Pazos <pazosenrique at gmail.com>
> wrote:
>
>> Dear Sudipta Ghosh,
>>
>> I ran into the same problem with high resolution (ds < 20 km). The
>> problem was solved using the non-hydrostatic core, i.e. setting the
>> parameter
>>
>> idynamic = 2
>>
>> I hope this helps.
>>
>> Regards,
>>
>> e.
>>
>> On Wed, Aug 9, 2017 at 2:06 AM, SUDIPTA GHOSH <sudiptaghosh006 at gmail.com>
>> wrote:
>>
>>> Hello All,
>>>
>>> I tried to run a 5year simulation with RegCM4.5 with dx=25km and dt=30
>>> secs but the model stopped due to CFL violation after 6month simulation. I
>>> decreased the dt to 25, 20 and 15 still the job got killed due the same
>>> reason, however the simulation period varied each time.
>>>
>>> Next I tried to run a 2 year simulation with RegCM4.4 at the same
>>> combination of dx and dt but again the problem occurred. I even tried
>>> changing the vertical levels from 18 to 23 but no run was completed.
>>>
>>> Next I changed the resolution to 50km and tried with following
>>> combinations:
>>>
>>> ds=50km dt=150secs
>>> ds=50km dt=120secs
>>> ds=50km dt =100secs
>>>
>>> But the same error as above is persisting.
>>>
>>> I will be highly obliged if anyone can kindly advice for the same.
>>>
>>> I have tried to run the job on 360, 300, 240 and 200 processors as well.
>>> However the message in each log file is as follows:
>>>
>>> WHUUUUBBBASAAAGASDDWD!!!!!!!!!!!!!!!!
>>>  No more atmosphere here....
>>>  CFL violation detected, so model STOP
>>>  #####################################
>>>  #            DECREASE DT !!!!       #
>>>  #####################################
>>>  WHUUUUBBBASAAAGASDDWD!!!!!!!!!!!!!!!!
>>>  No more atmosphere here....
>>>  CFL violation detected, so model STOP
>>>  #####################################
>>>  #            DECREASE DT !!!!       #
>>>  #####################################
>>>  Abort called by computing node          345 at 2017-05-08 18:29:32.161
>>> +0530
>>>  Abort called by computing node          329 at 2017-05-08 18:29:32.162
>>> +0530
>>> ------------------------------------------------------------
>>> --------------
>>> MPI_ABORT was invoked on rank 345 in communicator MPI COMMUNICATOR 3 DUP
>>> FROM 0
>>> with errorcode 1.
>>>
>>> NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
>>> You may or may not see output from other processes, depending on
>>> exactly when Open MPI kills them.
>>>
>>> --
>>> Regards
>>>
>>> Sudipta Ghosh
>>> PhD Scholar, Center for Atmospheric Sciences
>>> Indian Institute of Technology Delhi,India.
>>>
>>> _______________________________________________
>>> RegCNET mailing list
>>> RegCNET at lists.ictp.it
>>> https://lists.ictp.it/mailman/listinfo/regcnet
>>>
>>
>>
>>
>> --
>> Enrique Pazos, Ph.D.
>> Director Departamento de Postgrado
>> Escuela de Ciencias Físicas y Matemáticas
>> Universidad de San Carlos de Guatemala
>> http://fisica.usac.edu.gt/~epazos/
>>
>
>
>
> --
> Regards
>
> Sudipta Ghosh
> PhD Scholar, Center for Atmospheric Sciences
> Indian Institute of Technology Delhi,India.
>



-- 
Enrique Pazos, Ph.D.
Director Departamento de Postgrado
Escuela de Ciencias Físicas y Matemáticas
Universidad de San Carlos de Guatemala
http://fisica.usac.edu.gt/~epazos/
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