Fluids

Fluids

Different way to restart analysis in system coupling

    • Luigi0
      Subscriber
      Hi,nI have to make a fluid-structure analysis with system coupling. During the analysis I have to change the timestep, but I know that the timestep must be fixed during the run in system coupling.nSo I made 2 analysis in succession, when I have to change the timestep, the analysis is stopped and then restarted with a new timestep.n1) To avoid the stopping and the restarting, is there a way to define the change in the timestep before the analysis begins?n2) A discrete phase is present in my analysis. After the restart it seems that also the trajectories related to the first part of the analysis are recalculated, but now based on the new flow field. Do you have any advice on how to manage the dpm solutions when the analysis is restarted?n
    • Stephen Orlando
      Ansys Employee
      Hi Luigi,nI recommend taking a look at the following tutorial run with the System Coupling GUI or Command Line Interface that is run outside of Workbench: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/sysc_tut/sysc_tut_oscplate_cli_fluent.htmlnWith this, you can use Python logic in the run.py script to prescribe a variable timestep. For example the following will change the timestep to 0.2s then run for 10 timesteps.nDatamodelRoot().CouplingControl.AnalysisType.StepControl.TimeStepSize = '0.2 [s]'nStep(Count = 10)nYou could even add more complex Python logic to read data from a Fluent output file (Courant number for example), then base the new timestep on that data. You can read more about the Step() function here: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/sysc_ref/sysc_ref_commands_step.html?q=step()nSteven
    • Luigi0
      Subscriber
      Thanks,nso I have to use use command line interface? Is it not possible with system coupling GUI?n
    • Stephen Orlando
      Ansys Employee
      That's correct, you'll need to use the Command Line Interface (CLI).n
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