CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

pressure iterations not converging

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

Like Tree1Likes
  • 1 Post By dmilano

Reply
 
LinkBack Thread Tools Display Modes
Old   August 9, 2012, 12:54
Default pressure iterations not converging
  #1
New Member
 
Vikram Reddy
Join Date: Jun 2012
Posts: 13
Rep Power: 5
VikramR is on a distinguished road
Hello everyone, I am trying to model a reactor and I am having a few difficulties in doing so. The pressure iterations are not converging ( I tried setting max iterations to 5000, GMRES etc).
Are there any strategies to make it converge?
Please help.

Thanks in advance,
Vikram
VikramR is offline   Reply With Quote

Old   August 13, 2012, 18:10
Default
  #2
Member
 
Join Date: Mar 2012
Posts: 71
Rep Power: 5
dmilano is on a distinguished road
Well, there are a lot of things that you can try... Check the troubleshooting section of the manual for suggestions. My recommendations:

1. Check that the initial and boundary conditions are reasonable and match reality.
2. Check any STL files for problems
3. Check your mesh. Cell aspect ratios should be less than ~3:1; ideally closer to 1:1. The cell size should not change by more than a factor of two between multi-block meshes and the grid lines should align.
4. Check that epsi/epsadj are reasonable
5. Try adding some fluid compressibility (rcsql/rcsqv)
6. Reduce the time step size
7. Increase GMRES subspace size (mrstrt)
8. Try SOR with omega<1 and itmax ~5000

As a side note, using itmax=5000 with GMRES usually doesn't work well. If the problem doesn't converge with the default settings it is usually an indicator of some other problem.
Flowdy likes this.
dmilano is offline   Reply With Quote

Old   August 13, 2012, 18:13
Default
  #3
New Member
 
Vikram Reddy
Join Date: Jun 2012
Posts: 13
Rep Power: 5
VikramR is on a distinguished road
Thank you very.
I figured it out, the problem was with my initial conditions.
Thanks again Mr. dmilano
VikramR is offline   Reply With Quote

Reply

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
transsonic nozzle with rhoSimpleFoam Unseen OpenFOAM Running, Solving & CFD 7 April 16, 2014 03:38
Interfoam blows on parallel run danvica OpenFOAM Running, Solving & CFD 16 December 22, 2012 03:09
lift and drag on ship superstructures vaina74 OpenFOAM Running, Solving & CFD 3 June 8, 2010 12:30
Differences between serial and parallel runs carsten OpenFOAM Bugs 11 September 12, 2008 11:16
Modeling in micron scale using icoFoam m9819348 OpenFOAM Running, Solving & CFD 7 October 27, 2007 00:36


All times are GMT -4. The time now is 20:58.