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

How to detect errors in the mesh

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 29, 2009, 03:57
Default How to detect errors in the mesh
  #1
New Member
 
Rosa Esposito
Join Date: May 2009
Posts: 5
Rep Power: 8
rosaesposito is on a distinguished road
Hallo to everyone.
I am solving one case with the electromagnetic features, and the simulation clerly diverges due to one error in the mesh that I don't manage to find.
I am aware that with electromagnatic feature parameteres like the Volume Change are quite important, and I tried to have one uniform mesh.
Unfortunately, I have to reduce the numebr of nodes somewhere, in order to not have some kind of 10000000 nodes simulation.
My question is: if I manage to change something in the output parameter in PRE, can I detect the point of the mesh who gives me problems, and so to try to change the mesh with one purposefully strategy?
I can upload the file somewhere, every help is welcome.
rosaesposito is offline   Reply With Quote

Old   May 29, 2009, 07:05
Default
  #2
Member
 
Join Date: Mar 2009
Posts: 44
Rep Power: 8
Timon is on a distinguished road
Output the equation residuals and look up where the maximum residual occurs. This will give you an idea of the source of your (mesh-related) convergence issues.
Timon is offline   Reply With Quote

Old   May 29, 2009, 07:24
Default
  #3
New Member
 
Rosa Esposito
Join Date: May 2009
Posts: 5
Rep Power: 8
rosaesposito is on a distinguished road
Thanks a lot. I did it.
The mesh is something like 5000000 nodes and I need some time for the results.
My problem is: the simulation is good, till something goes wrong and the in some part of the mesh the Temperature jumps to high (not acceptable) values, and then diverges.
So, if I understood good, is it enough to look whare the residual have some high values, and there I find the problem?

Last edited by rosaesposito; May 29, 2009 at 07:35. Reason: Grammar error ;-)
rosaesposito is offline   Reply With Quote

Old   May 29, 2009, 07:56
Default
  #4
Member
 
Join Date: Mar 2009
Posts: 44
Rep Power: 8
Timon is on a distinguished road
Basically yes. It at least gives you an idea at which location the solver breaks down. If you find bad element-quality in this area then convergence might be helped by improving the mesh locally. Otherwise, try reducing your timestep...
Timon 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
Hex-Tet Mesh Merge in ICEM Tristan CFX 1 September 26, 2008 05:40
how to extend FSI 2D codes to 3D, need advises abouziar Main CFD Forum 1 May 30, 2008 04:08
ICEM 10 mesh question DAK565656 CFX 6 May 8, 2007 12:16
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 18:10
General questions on grid-based computing Adrin Gharakhani Main CFD Forum 21 June 5, 2000 13:47


All times are GMT -4. The time now is 04:08.