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

Convergence problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 17, 2007, 03:17
Default Convergence problem
  #1
akr
Guest
 
Posts: n/a
Hi, I want to solve gas flow in chamber. The geometry of chamber is 0.3 in width, 0.3 in height and 0.05 m in depth. The inlet is circle whose diameter is 0.013 m and set on the side face (0.3 by 0.05 m). The outlet is also circle whose diameter is 0.013 m and set on top face (0.3 by 0.05 m). The inlet is velocity inlet boundary and the velocity is 2.5 m/s. The outlet is pressure outlet boundary. And I am solving with laminar model. When this calculation starts, the residual decrease to 10-2. But after that, the residual keeps flat and never decrese. Is this converge? Thanks, akr
  Reply With Quote

Old   May 17, 2007, 04:21
Default Re: Convergence problem
  #2
Adriano
Guest
 
Posts: n/a
Hi, Try to check the under relaxation factors (reducing them), try to change discretization scheme and pressure-velocity coupling scheme (i.e.: Simple). After, If You don't reach convergence, check your mesh!

Hope it's helpful,

best regards Adriano
  Reply With Quote

Old   May 17, 2007, 10:27
Default Re: Convergence problem
  #3
Madhukar
Guest
 
Posts: n/a
Hi

U had the same question, which i had 2 days back.... there was a small but valuable discussion on this topic yesturday in the forum...you can find it under

http://www.cfd-online.com/Forum/fluent.cgi?read=48852

regards
  Reply With Quote

Old   May 17, 2007, 20:59
Default Re: Convergence problem
  #4
akr
Guest
 
Posts: n/a
Thank you for your responses. I will also try to use turbulence model instead of laminar model. But now what I don't understand is which model is best for my case. In my case, reynolds number is about 3000 at inlet. Do you know which one is best??

Regards, akr
  Reply With Quote

Old   May 18, 2007, 07:21
Default Re: Convergence problem
  #5
Madhukar
Guest
 
Posts: n/a
Give a try with standard K-Eps Model

Regards

Madhukar
  Reply With Quote

Old   May 19, 2007, 02:24
Default Re: Convergence problem
  #6
akr
Guest
 
Posts: n/a
Hi Madhukar,

Is it O.K. to use standard K-Eps model in my case? In the chamber, fluid velocity is not high. And reynolds number is small.

Regards, akr
  Reply With Quote

Old   May 22, 2007, 07:49
Default Re: Convergence problem
  #7
Madhukar
Guest
 
Posts: n/a
Hi,

If the Reynold's number is very less ....you try with RNG K-Eps., model.

regards
  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
convergence problem when use pisoFoam, LES for wind tunnel case Forrest_Lei OpenFOAM 3 July 19, 2011 06:00
convergence problem commonyue Main CFD Forum 1 December 1, 2009 04:54
Convergence of CFX field in FSI analysis nasdak CFX 2 June 29, 2009 01:17
3D Fluid Flow Convergence problem Emily FLUENT 2 March 21, 2007 23:18
Non Convergence of 3D Heat transfer cfd problem Balraj Main CFD Forum 3 December 9, 2004 01:24


All times are GMT -4. The time now is 19:45.