# change timestep after a certain iteration number

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 May 31, 2007, 05:03 change timestep after a certain iteration number #1 Sans Guest   Posts: n/a Hi, I observe that my problem starts to diverge after say 60-70 iterations, but it is soon rectified when I reduce the timestep. But during a batch run I would like to do the same. Is it possible to change the timestep after a specified iteration during a batch run (command line)? Thanks...

 May 31, 2007, 08:12 Re: change timestep after a certain iteration numb #2 Gert-Jan Guest   Posts: n/a I do it every day.... Physical Timescale = min(1e-2[s],max(5e-3[s],2e-2[s]-citern*1e-4[s])) Plot it in Pre to find out how it looks like. Gert-Jan www.bunova.nl

 June 1, 2007, 00:58 Re: change timestep after a certain iteration numb #3 Sans Guest   Posts: n/a Thanks a lot Gert-Jan, Now it strikes me...or inturn I can also use a fuction in PRE

 June 1, 2007, 03:27 Re: change timestep after a certain iteration numb #4 Jack Guest   Posts: n/a Hi! Gert-Jan, I think This is also useful to me, could you please explain the meaning of "min(1e-2[s],max(5e-3[s],2e-2[s]-citern*1e-4[s]))", since I am quite new to CFX. Thanks

 June 1, 2007, 04:56 Re: change timestep after a certain iteration numb #5 Gert-Jan Guest   Posts: n/a It is mathematics. The only unknown thing is citern which is the current iteration number. You can also use aitern which is the accumulated iteration number. Just play around in Pre or a spreadheet to see what the function does... Gert-Jan www.bunova.nl

 June 3, 2007, 05:17 Re: change timestep after a certain iteration numb #6 Sameer Guest   Posts: n/a Hi. There is another way is to use step function. suppose timestep upto 60th iteration is 0.025 [s] and after 60th iteration it is tobe reduced to 0.002 [s], you may use following step function, Timestep = 0.025[s]*step(aitern-60)+0.002[s]*step(60-aitern). Sameer

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post kus CFX 9 April 21, 2013 01:54 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03 steven CFX 2 March 7, 2007 12:58 HS FLUENT 0 December 1, 2005 06:16 lenson Siemens 3 October 10, 2005 06:40

All times are GMT -4. The time now is 04:36.

 Contact Us - CFD Online - Privacy Statement - Top