Time step calculation

Noman Hafeez · October 23, 2017, 06:58

how we can calculate the time step and total time for tidal turbine?what do you mean by turbine rotates 1 degree or 2 degree during each time step?is there any formula for time step and total time?
And what should be the convergence criteria for transient simulations?

ghorrocks · October 23, 2017, 08:05

Total time: That should the time required to get the results you need. So this is entirely up to you:

Time step size: Use adaptive time stepping, homing in on 3-5 coeff loops per iteration and you don't need to calculate it, CFX will find it automatically.

Convergence criteria: Do a sensitivity analysis and work it out. It is different for different simulations so you have to find what is required in your case. While you are at it, do a sensitivity analysis on mesh size as well. That is the other important tunable parameter for accurate results.

October 23, 2017, 06:58	Time step calculation	#1
Noman Hafeez New Member Noman Hafeez Join Date: Jul 2017 Posts: 6 Rep Power: 9	how we can calculate the time step and total time for tidal turbine?what do you mean by turbine rotates 1 degree or 2 degree during each time step?is there any formula for time step and total time? And what should be the convergence criteria for transient simulations?

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October 23, 2017, 08:05		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Total time: That should the time required to get the results you need. So this is entirely up to you: Time step size: Use adaptive time stepping, homing in on 3-5 coeff loops per iteration and you don't need to calculate it, CFX will find it automatically. Convergence criteria: Do a sensitivity analysis and work it out. It is different for different simulations so you have to find what is required in your case. While you are at it, do a sensitivity analysis on mesh size as well. That is the other important tunable parameter for accurate results.