CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Misleading low Residuals long before Steady state solution is reached!

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 20, 2013, 07:16
Default Misleading low Residuals long before Steady state solution is reached!
  #1
New Member
 
lreflow
Join Date: Jul 2013
Posts: 1
Rep Power: 0
lreflow is on a distinguished road
Hello dear Foamers,
I am doing a turbulent incompressible steady state Simulation involving a porous media using porousSimpleFoam.
While my pressure Residuals drop below 1e-3 after about 1000 iterations and then oscillate slightly around 5e-4 , I have obviously not reached my steady state solution at this point as can be seen in Uplot.png where the velocities at 4 points on the surface of the porous media are plotted against the iterations. Judging by the residuals alone I would have stopped the simulations way to early. I am wondering what could cause this situation where the residuals are a very bad measure of convergence?
I set a low relaxation factor for the velocity following these guidelines:
http://www.kxcad.net/star-ccm/online...edFlow-09.html

The realizable kepsilon model was switched on after 300 iterations.
I attached my checkMeshlog my fvSolution and fvSchemes file.

I have to do a parameter study and if possible I would like to reduce the necessary number of iterations before starting with it.

Thanks for any help and thoughts on this.

Best wishes,
lreflow
Attached Images
File Type: png Uplot.png (22.7 KB, 8 views)
Attached Files
File Type: txt fvSolution.txt (1.9 KB, 4 views)
File Type: txt fvSchemes.txt (2.5 KB, 1 views)
File Type: txt logM.txt (3.3 KB, 2 views)
lreflow is offline   Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Analytic solution for 2D steady Euler equations jojo81 Main CFD Forum 0 October 15, 2012 13:05
outflow boundary in a steady state 1D convection diffusion eq. hans-186 Main CFD Forum 2 October 14, 2012 18:39
Transient Solution looks like Steady State ljwnow FLUENT 0 March 26, 2012 02:54
No steady state solution Danny Tandra Main CFD Forum 1 September 23, 2004 03:18
About the difference between steady and unsteady problems Lisa Main CFD Forum 11 July 5, 2000 15:37


All times are GMT -4. The time now is 22:25.