CFD Online Logo CFD Online URL
Home > Forums > CFX

Small timestep make the simulation not converge

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   August 7, 2012, 16:09
Question Small timestep make the simulation not converge
Senior Member
Anna Tian's Avatar
Meimei Wang
Join Date: Jul 2012
Posts: 494
Rep Power: 7
Anna Tian is on a distinguished road

I was stuck by the convergence problem for whole the last week. Today I accidentally find out why. The reason is I used too small time step. But the FAQ suggests us to use small timestep to make our simulation converge. Could you explain why sometimes, to the contrary of the theory, small time step might even prevent convergence?
Best regards,
Anna Tian is offline   Reply With Quote

Old   August 7, 2012, 19:25
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,045
Rep Power: 86
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
If your time step gets too small then round off errors can become large. Then the noise from round off error means convergence is difficult.
ghorrocks is offline   Reply With Quote


Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to make simulation of body force in plasma actuator induce flow? mukut Phoenics 25 April 7, 2011 22:35
Timestep for transient simulation houman CFX 2 April 28, 2005 03:44
flow simulation across a small fan jane luo Main CFD Forum 15 April 12, 2004 17:49
Numerical simulation on small poo fires Yun Kang Main CFD Forum 5 June 25, 2003 06:25
timestep for combustion simulation yangqing FLUENT 0 August 18, 2002 08:46

All times are GMT -4. The time now is 09:38.