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

An adequate meshing

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 12, 2002, 09:15
Default An adequate meshing
  #1
Julie
Guest
 
Posts: n/a
Hi!

How can I define if the mesh I'm using is good enough? I've already made few mesh refinements, but each of them gives more and more strange results.

Thanks,

Julie
  Reply With Quote

Old   February 13, 2002, 03:00
Default Re: An adequate meshing
  #2
Ossi
Guest
 
Posts: n/a
Unfortunately for turbulent flows the only way to determine a good enough grid size is to compare different mesh densities and hope that at some point the changes will be small enough to conclude that a certain mesh density is 'good enough'. Additionally, it is always also a play between accuracy and computational time.

Good luck !
  Reply With Quote

Old   February 13, 2002, 04:14
Default Re: to Ossi
  #3
Julie
Guest
 
Posts: n/a
Hi, Ossi!

The problem is that I've already tried 3 different meshes (~3000, ~9000 and ~34000 (!) cells) and each of them gives different (on my opinion, more and more strange) results. The only explanation I have that the choosen geometry is not good for the problem beeing solved.

Thanks anyway,

Julie
  Reply With Quote

Old   February 13, 2002, 04:22
Default Re: to Ossi
  #4
Ossi
Guest
 
Posts: n/a
I do not know what kind of a problem you are dealing with but if it is a 3-D geometry, then the 30 000 cells do not sound too much.
  Reply With Quote

Old   February 13, 2002, 09:43
Default Re: An adequate meshing
  #5
allan
Guest
 
Posts: n/a
perhaps you do not have enough cells, or tou may be trying to solve your case steady state and is in fact transient, or how do you know your case is converged in eash run, are the residuals still dropping even though you have reached the default convergence criteria, if so try setting the convergence criteria to 1e-6 in your models. Also try comparing flow fields from different iteration numbers in your solution and see if they are changing. You can actually subtract flowfield variables from different iteration numbers by using the operate command.

cheers

allan
  Reply With Quote

Old   February 14, 2002, 04:34
Default Re: to Ossi
  #6
Julie
Guest
 
Posts: n/a
Hi, Ossi!

The geometry I deal with is a sector with one cell layer in the angular direction.

Cheers,

Julie
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hexa meshing or Tetra meshing??? NITIN DEWANGAN CFX 5 August 5, 2008 10:59
Adequate Boundary Conditions Florian Longueteau Main CFD Forum 3 August 9, 2007 10:58
3D meshing in Ga,bit Aly FLUENT 8 August 19, 2005 15:38
Singularity of grid?Volume meshing vs face meshing Ken Main CFD Forum 0 September 4, 2003 12:09
Volume Meshing & Face Meshing? singularity of grid ken FLUENT 0 September 4, 2003 12:08


All times are GMT -4. The time now is 16:53.