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

problems with VERY simple mesh

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 17, 2006, 01:21
Default problems with VERY simple mesh
  #1
Ralf Schmidt
Guest
 
Posts: n/a
Hi!

I have a very simple mesh in gambit (2D, about 5000 tri cells, only 10 cells with an equiSize Skew higer than 0.22).

Now, exporting to and importing in Fluent is no problem. Performing a grid check is ok as well. Now, I turned the solver to axissymmetric and activate k-epsilon modell. After that, a new grid chek failed:

WARNING: non-positive volumes exist.

Waht happend???

ANY idea??

Ralf
  Reply With Quote

Old   October 17, 2006, 01:24
Default Re: problems with VERY simple mesh
  #2
mAx
Guest
 
Posts: n/a
check if your revolution axis is absolute coincident with your x-axis
  Reply With Quote

Old   October 17, 2006, 01:35
Default Re: problems with VERY simple mesh
  #3
Claud
Guest
 
Posts: n/a
and it should be only in positive direction on both axis.
  Reply With Quote

Old   October 17, 2006, 01:37
Default Re: problems with VERY simple mesh
  #4
Ralf Schmidt
Guest
 
Posts: n/a
Hi, thx for answer...

that might be the problem, but: First, I had the axis BC parallel to the y-axis, now it is coincident to the x-axis. But the problem still appears when i turn on the axis-symmetric solver.

Ralf

  Reply With Quote

Old   October 17, 2006, 01:45
Default Re: problems with VERY simple mesh
  #5
Ralf Schmidt
Guest
 
Posts: n/a
it is, but that doen't help...
  Reply With Quote

Old   October 17, 2006, 02:33
Default Re: problems with VERY simple mesh
  #6
mAx
Guest
 
Posts: n/a
check if the revolution axis lie exactly on the x-axis. a small gap about 1e-3 under the x-axis will crash the grid check
  Reply With Quote

Old   October 17, 2006, 05:54
Default problem solved!
  #7
Ralf Schmidt
Guest
 
Posts: n/a
Hi!

in the domain extents it is visible: the y domain starts from -1.2 e-14 - so there are some nodes below the x-axis!!

I solved the problem - editing the msh file: exchanging all y values below 0 to 0. Another way: translating the whole mesh in y-direction.

It works fine now... but why does fluent (or gambit) produces that problem???

Ralf
  Reply With Quote

Old   October 17, 2006, 07:21
Default Re: problems with VERY simple mesh
  #8
sach
Guest
 
Posts: n/a
hey have you checked right handed ness or left handed ness problem
  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
[ICEM] surface mesh merging problem everest ANSYS Meshing & Geometry 44 April 14, 2016 06:41
[ICEM] Using a hybrid mesh for a simple pipe Udio_NT ANSYS Meshing & Geometry 17 October 18, 2012 14:42
[GAMBIT] Error on simple mesh Rich1979 ANSYS Meshing & Geometry 3 August 16, 2010 05:21
external flow with snappyHexMesh chelvistero OpenFOAM 11 January 15, 2010 20:43
Icemcfd 11: Loss of mesh from surface mesh option? Joe CFX 2 March 26, 2007 18:10


All times are GMT -4. The time now is 18:35.