About changing time step at the CFX-solver
 

Hi,

May I ask if there's any way to change the time step at the CFX-solver? So that when I want to change the time step to let the RMS converge I can stop the simulation and change it directly without going back to CFX-pre. Then start the running again with the result before changing the time step as the initial data.

Thank you very much.

Yes there is a button to edit the run in progress.

For a stady state run use the edit run in progress option in the solver manager. For a transient state run use adaptive time stepping, converging on 3-5 coeff loops per iteration.

Thanks! But is there a way that I can set the change in advance and change it automatically during the running? Like I can set when the convergence stop, it changes its time step to another value. Or when it reaches a time step number (for example, like 500), it changes to another.

Yes you can give multiple timesteps. See the section of the CFX manual entitled "Transient Timestep Control". You can give a comma separated list, but in your case it's probably better to write an expression that gives the timestep.

Thanks. But I work on the steady-state flow. And I always would like to change my time step from local time step of factor 5 to physical time step of 10^-4 in the middle of the simulation (when RMS doesn't decrease any more). How to make it changes automatically?

Set it up as two runs, one which does the local time step bit and a second which uses that as an initial condition for a physical time step run. The automate is by using a batch/script file so you can run it all from a single command.