CFD Online Logo CFD Online URL
Home > Forums > FLUENT


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

LinkBack Thread Tools Display Modes
Old   December 20, 2007, 07:13
Default Divergence
Posts: n/a

I encountred a problem of divergence with continuity, and velocity residuals, especially when I put a large number of iteration per time step. How can I solve to that? Thanks.
  Reply With Quote

Old   December 27, 2007, 21:04
Default Re: Divergence
Posts: n/a
What is the problem you are trying to solve? what are ur Bcs, under-relaxation factors?
  Reply With Quote

Old   December 28, 2007, 05:42
Default Re: Divergence
Posts: n/a

I encountred a problem of divergence with continuity and velocity residuals, especially when I put a large number of iterations per time step (>=10). I should mention that this doesn't happen if small number of iteration is put. (1-5).

Even,I lowed the under relaxation factors of pressure (0.3-0.4), momentum (0.4)! Or changed the initial velocities, or turned off the energy equation for first iterations, in vain!

it gives this error message: Error: divergence detected in AMG solver: vof-1 and then: Error: floating point error: overflow Error Object: ()

What do you think, what can be the cause?

  Reply With Quote

Old   January 1, 2008, 04:48
Default Re: Divergence
Posts: n/a
Hi Safa, From what you have given here, it looks like you are trying to solve a multiphase problem. VOF-Liquid may suddenly shot up to a value that could have led to the divergence. There is no easy answer to this except continually experimenting with the URFs. With regard to the no. of iterations, is ur problem converging in each time-step when you reduce the no of iterations per time-step?
  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
UDF divergence of a vector cris FLUENT 3 September 4, 2014 18:06
Divergence problem for species transport model MY FLUENT 3 January 11, 2014 05:46
Quarter Burner mesh with periosic condition SamCanuck FLUENT 2 August 31, 2011 11:34
divergence in MAC Method Maciej Matyka Main CFD Forum 2 December 19, 2000 11:43
help:spectral methods & divergence free functionsn D. Puigjaner Main CFD Forum 1 August 28, 2000 10:06

All times are GMT -4. The time now is 08:09.