Time step

March 14, 2006, 09:40

Hi all how should we decide the time step in an unsteady flow?

March 14, 2006, 12:49

You should set a Time Step Size so that the number of iterations necessary to get convergence at each time step is 5-10. If converce at each time step requires more than 5-10 iterations then reduce the Time Step Size. If converce at each time step requires less than 5-10 iterations then you can increase the Time Step Size.

March 14, 2006, 12:52

You should set a Time Step Size so that the number of iterations necessary to get convergence at each time step is 5-10. If convergence at each time step requires more than 5-10 iterations then reduce the Time Step Size. If convergence at each time step requires less than 5-10 iterations then you can increase the Time Step Size.

March 16, 2006, 08:59

The advise above is acceptable only for small cases when time is not a critical issue.

Your timestep has to be at least 2-5 times less than a period of smallest disturbance in your flow.

March 14, 2006, 09:40	Time step	#1
anand Guest Posts: n/a	Hi all how should we decide the time step in an unsteady flow?

March 14, 2006, 12:49	Re: Time step	#2
dan Guest Posts: n/a	You should set a Time Step Size so that the number of iterations necessary to get convergence at each time step is 5-10. If converce at each time step requires more than 5-10 iterations then reduce the Time Step Size. If converce at each time step requires less than 5-10 iterations then you can increase the Time Step Size.

March 14, 2006, 12:52	Re: Time step	#3
dan Guest Posts: n/a	You should set a Time Step Size so that the number of iterations necessary to get convergence at each time step is 5-10. If convergence at each time step requires more than 5-10 iterations then reduce the Time Step Size. If convergence at each time step requires less than 5-10 iterations then you can increase the Time Step Size.

March 16, 2006, 08:59	Re: Time step	#4
Oleksiy Dushyn Guest Posts: n/a	The advise above is acceptable only for small cases when time is not a critical issue. Your timestep has to be at least 2-5 times less than a period of smallest disturbance in your flow.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
HELP! time step too small?	meangreen	Main CFD Forum	6	May 31, 2018 10:41
Superlinear speedup in OpenFOAM 13	msrinath80	OpenFOAM Running, Solving & CFD	18	March 3, 2015 05:36
Hydrostatic Pressure and Gravity	miliante	OpenFOAM Running, Solving & CFD	132	October 7, 2012 22:50
Full pipe 3D using icoFoam	cyberbrain	OpenFOAM	4	March 16, 2011 09:20
calculation diverge after continue to run	zhajingjing	OpenFOAM	0	April 28, 2010 04:35