CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

Residuals converge then explode

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

LinkBack Thread Tools Display Modes
Old   December 29, 2011, 06:25
Default Residuals converge then explode
New Member
Join Date: Nov 2011
Posts: 22
Rep Power: 8
plm is on a distinguished road
Hi all,

Can anyone explain what is happening when a solution starts to converge and then gets so far and starts to go the opposite way, eventually exploding into an error.....

I'm a bit unsure about why this should occur and what it means about how much I can trust the results when they are converged the most (before explosion).

Does this indicate a problem, specifically in the fvSchemes used to solve the problem perhaps?

Any thoughts would be welcome and thanks for your time.
plm is offline   Reply With Quote

Old   December 30, 2011, 13:45
Default More Info Needed
New Member
Michael Ahlmann
Join Date: Feb 2010
Posts: 27
Rep Power: 9
danishdude is on a distinguished road
Can you provide more detail about your case? Post the case if it's not too large, or at least post the boundary condition files, fvSchemes, and fvSolutions.

I've seen similar behavior when using a zeroGradient condition on the outlet velocity; however, during the transients, a local vortex develops leading to a reverse flow condition. If that's what's happening, you can fix it by changing from a zeroGradient to an inletOutlet condition.
danishdude is offline   Reply With Quote

Old   December 31, 2011, 08:35
New Member
Join Date: Nov 2011
Posts: 22
Rep Power: 8
plm is on a distinguished road
Hi danishdude, thanks for your time.
I'm trying ultimately to model a turbine blade using LES, but as a starting point i'm trying to use a RANS approach with simpleFoam. I'm using an unstructured mesh generated with gmsh.

I am indeed using a zeroGradient bc on the outlet, and though I'm not familiar with the inletOutlet bc I'll try and give it a go.

Here's a copy of some of the case files, I'd be very interested on your thoughts.

Attached Files
File Type: zip (4.4 KB, 2 views)
plm 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
Tutorial of how to plot residuals ! wolle1982 OpenFOAM Running, Solving & CFD 142 February 23, 2017 10:07
what to monitor besides residuals? franzdrs FLUENT 5 March 21, 2013 04:59
Mesh size and solver residuals... Scott CFX 5 December 15, 2008 18:10
Convergence - scaled vs unscaled residuals HS FLUENT 1 November 7, 2005 06:45
Converge problem for multiphase flow Jen FLUENT 4 July 20, 2005 16:52

All times are GMT -4. The time now is 09:46.