Time step calculation

Noman Hafeez · October 23, 2017, 05:58

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, 07:05

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, 05:58	Time step calculation	#1
Noman Hafeez New Member Noman Hafeez Join Date: Jul 2017 Posts: 6 Rep Power: 8	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?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
pimpleDyMFoam computation randomly stops	babapeti	OpenFOAM Running, Solving & CFD	5	January 24, 2018 05:28
Floating point exception error	lpz_michele	OpenFOAM Running, Solving & CFD	53	October 19, 2015 02:50
time step directories naming issue	Andrea_85	OpenFOAM	3	April 3, 2014 08:38
How to write k and epsilon before the abnormal end	xiuying	OpenFOAM Running, Solving & CFD	8	August 27, 2013 15:33
calculation diverge after continue to run	zhajingjing	OpenFOAM	0	April 28, 2010 04:35

October 23, 2017, 07:05		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,716 Rep Power: 143	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.