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

[SUDIPTA GHOSH]

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.
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