Adaptive Time Step not working?

Questions and other topics related to UEMS 18.
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norulz
Posts: 92
Joined: Thu Mar 12, 2015 1:43 pm

Adaptive Time Step not working?

Post by norulz » Sat Jan 13, 2018 10:20 am

Hi all,

Time step with V18.1.0 appears to be fixed even with ADAPTIVE time step activated.
Has anyone else seen this?

David

norulz
Posts: 92
Joined: Thu Mar 12, 2015 1:43 pm

The problem is with the defaults

Post by norulz » Sat Jan 13, 2018 11:44 am

OK...

it is working but the default setting have changed which ends up in a rather slow run at fixed times.

With a 12km/4km domain run the actual starting time step is 48/16 seconds (DX * 4). Then it increases and settles on a maximum of 96/32 seconds (DX * 8). I would normally see fluctuation of timing between 120 - 180 second for d01 in V15.

According to the default setting -1 for STARTING_TIME_STEP should be DX * 6 (72/24 seconds in my case); -1 for MAX_TIME_STEP should be START * 3 (216/72 seconds in my case).

WORKAROUND appears to be by setting actual numbers instead of all the defaults. For my 12km/4km domain I'm now using 48/16 for START, 180/60 for MAX and 24/8 for MIN

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