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

help!!!gambit again

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 12, 2001, 13:23
Default help!!!gambit again
  #1
shery
Guest
 
Posts: n/a
Hi, I'm trying to mesh a geometry in GAMBIT.The geometry is not very complex but there are some small gaps in there that seems to cause problem in meshing.I'm using Tgrid and every time I try to mesh I get this error massage:" Tetahedral meshing has failed for volume ....this is usually caused by problems in the face meshes.chck the skewness of your face meshes and make sure the face mesh sizes are not too large in areas of small gaps". I had this problem before and by editing some of the defaults I was able to mesh the geometry.But it doesn't seem to work for this one. I appreciate your help. shery
  Reply With Quote

Old   January 13, 2001, 17:53
Default Re: help!!!gambit again
  #2
Raza Mirza
Guest
 
Posts: n/a
Hi Shery,

The error message from TGrid seems to be fairly descriptive. TGrid, or for that matter any other tet mesher, does not like skewed faces. So if there are fine gaps that need to be meshed, try to make sure that the face triangles in that region are as close to perfect (isosceles, sp???) as possible (that is close to skewness of zero). and then tranistion GRADUALLY from there to regions where you do not need to resolve gaps.

what software are you using for surface triangulation? is the quality of triangulation easily controllable?

  Reply With Quote

Old   January 14, 2001, 12:44
Default Re: help!!!gambit again
  #3
shery
Guest
 
Posts: n/a
Hi Raza, Thanks for your respond.I'm not sure how I can make the skewness zero in the gaps. I'm using gambit and I think I can't change the quality of trangulation easily.but can you tell me if I could change the quality,what should be changed? thanks again shery
  Reply With Quote

Old   January 15, 2001, 09:59
Default Re: help!!!gambit again
  #4
Sandeep
Guest
 
Posts: n/a
I had the same problem when meshing in Gambit. Unfortunately you dont have too much control over the tet mesh in gambit. In my case I decomposed the volume into smaller volumes and then meshed each of them with the tet mesh and it worked. You might want to give that a shot.
  Reply With Quote

Old   January 15, 2001, 12:34
Default Re: help!!!gambit again
  #5
shery
Guest
 
Posts: n/a
Thanks sandeep,I decomposed the volume didn't help that much.If you have any other suggestions please let me know.
  Reply With Quote

Old   January 16, 2001, 00:12
Default Re: help!!!gambit again
  #6
Raza Mirza
Guest
 
Posts: n/a
Hi Shery,

Although I do not have any experience with Gambit, I have experience with preBFC, fluent's old-old pre-processor. In that you could control the node distribution on the edges. This control would give you some control over surface triangulation. Now I use a third party software that gives me the same flexibility much more easily.

Short answer to your question: If you can control the node distribution on the edges, try putting nodes on the edges that describe the thin gaps such that the space between any two adjacent nodes is half the gap size (or smaller). I do work with geometries that have small gaps that I need to resolve and usually I control the node distribution to control the surface triangulation. In the software I use I can also control some other attributes of the surface mesh.

I hope it helps. As I said, I do not have any experience with Gambit. But I have found Fluent's user support to be very helpful. May be they can tell you if you can or can not control the node distribution.

  Reply With Quote

Old   January 16, 2001, 12:53
Default Re: help!!!gambit again
  #7
shery
Guest
 
Posts: n/a
thanks Raza for your help.it was very useful.I can control the node distribution on edges in Gambit. I did and it worked for me. thanks again
  Reply With Quote

Old   January 16, 2001, 18:52
Default Re: help!!!gambit again
  #8
Raza Mirza
Guest
 
Posts: n/a
i'm glad it worked out.
  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



All times are GMT -4. The time now is 11:12.