CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Problem with mesh generation

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 30, 2006, 06:32
Default Problem with mesh generation
  #1
Nestor
Guest
 
Posts: n/a
Hi there,

I've got a problem while trying to mesh a volume. I just want to know what this means:

"Initialization failed; perturb boundary nodes and try again.

Initialization failed to mesh 1 nodes. ERROR: TG_Mesh_Domain failed with error code 1. ERROR: Tetrahedral meshing has failed for volume entrada. This is usually caused by problems in the face meshes. Check the skewnesses of your face meshes and make sure the face mesh sizes are not too large in areas of small gaps."

The 2d elements' skewness are below 0.8, and the most part below 0.6. I've made sure that, more less, in the zones with small elements, there are other elements of the same size. But I donīt get any good result.

The former 2d meshes for the volume are Tri Pave based.

Any suggestion?

  Reply With Quote

Old   October 30, 2006, 09:22
Default Re: Problem with mesh generation
  #2
Jason
Guest
 
Posts: n/a
A 2D skewness of 0.8 is high when you're using that as your 3D base, and if it's in an area where the geometry is complex, this could be the problem. I typically shoot for a maximum of 0.7 (and I only allow a couple elements to be that skewed...). That's just based on personal experience.

If fixing that element doesn't fix the problem, then I recommend decomposing the volume into smaller volumes (if you use the split command with the connected option on, and don't define any BCs on these 'internal' faces, then Gambit will write the geometry as one continuous volume).

Decomposing the volume into smaller ones does two things... 1st, Gambit's meshing algorithms aren't the most robust (Fluent support will often recommend TGrid instead of Gambit for 3D meshes) so when you decompose the geometry, you create smaller, simpler volumes to be meshed, which takes the pressure off the algorithm. 2nd, it allows you to isolate the problem area. If you fix that cell with the .8 skewness and the problem still occurs, then you really don't know where the geometry is failing... there are ways of systematically searching the volume to try and find it, but those are tedious and time consuming... splitting the geometry is often quick and can narrow your search from hundreds or thousands of surfaces to a handfull of surfaces.

Hope this helps, and goodluck, Jason
  Reply With Quote

Old   October 30, 2006, 13:21
Default Re: Problem with mesh generation
  #3
Nestor
Guest
 
Posts: n/a
I really thank you Jason, I'll try to split the volume in simpler ones (anyway, one of them is gonna be a little more than simple) and search something about TGrid. My objectives are serious, but still not professional, I'm just a beginner.

I'll tell here how it evolves.

thanks again,

have a nice day
  Reply With Quote

Old   November 1, 2006, 03:54
Default Re: Problem with mesh generation
  #4
Nestor
Guest
 
Posts: n/a
Hi,

At last I've got to mesh the volumen, dividing it into smaller ones but also reducing the number of elements in each edge.

greetings
  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
[Other] engineFoam new mesh problem ayhan515 OpenFOAM Meshing & Mesh Conversion 5 August 10, 2015 09:45
[Gmsh] 2D Mesh Generation Tutorial for GMSH aeroslacker OpenFOAM Meshing & Mesh Conversion 12 January 19, 2012 04:52
Mesh generation problem Lam FLUENT 2 December 25, 2003 13:37
Latest News in Mesh Generation Robert Schneiders Main CFD Forum 1 February 18, 2000 01:48
Latest news in mesh generation Robert Schneiders Main CFD Forum 0 March 2, 1999 05:07


All times are GMT -4. The time now is 16:44.