Using adaptive timestep on Linux-based cluster

- May 4, 2020 at 11:10 am
  
  cg2308
  Subscriber
  
  Hi,
  
  I have used the GUI to setup .cas and .dat files that I am running on a cluster. For my simulation, I would like to use error based adaptive timestepping, however I cannot get this to work through the cluster. My .cas file contains the correct timestepping parameters in the GUI.
  
  Are there any text commands I should be using to apply error based adaptive timestepping?
  
  Thanks in advance
  
  P.S I have tried some commands which work in the Fluent console but do not work when inserted into my script file.
- May 4, 2020 at 4:05 pm
  
  Rob
  Forum Moderator
  
  No, it should work. What isn't behaving?
- May 4, 2020 at 10:11 pm
  
  cg2308
  Subscriber
  
  Hi - so these are my parameters; initial time step 1e-07s, maximum time step 1e-05s and minimum time step 5e-09s.
  
  When I run on the cluster, my initial time step is 1e-06s and remains this. When I run the same case through Workbench, my timestep begins at 1e-07s and then is adaptive.
  
  I have briefly run the same case on both platforms to compare below:
  
  Thanks
- May 5, 2020 at 10:53 am
  
  Rob
  Forum Moderator
  
  If you open the case up on the cluster what settings can you see? I'm wondering if the set up wasn't passed over, but I've not seen that happen before.
- May 6, 2020 at 10:21 am
  
  cg2308
  Subscriber
  
  Hi, sorry for the delayed response. I am new to using cluster and only know how to run my jobs in batch mode... I have removed the '-g' command from my fluent load line but I now get a display error that I will have to figure out.
  
  My supervisor and I have discussed and she thinks it is potentially related to the 'solve dual-time-iterate' text command in my script file. If I remove this my simulation doesn't run. Could this be the case? Thankyou
- May 6, 2020 at 3:55 pm
  
  Rob
  Forum Moderator
  
  Yes, that may be overwriting the adaptive time stepping. Test it on the Windows machine to see what it does, you may need a slightly different command.
  
  -g does something with the GUI for batch runs, if the cluster doesn't have graphics (or can't push them to the machine you're sat at) you may see an error.
- May 11, 2020 at 2:47 am
  
  cg2308
  Subscriber
  
  Hi rwoolhou,
  
  I think I have it working now. I have added some text commands which have allowed my adaptive time stepping to work. These stemmed from /solve/set/transient-controls/cfl-based-time-stepping and then adding my controls.
  
  Thanks for the help