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

Coupled Solver issues

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 1, 2004, 22:57
Default Coupled Solver issues
  #1
Allan Cross
Guest
 
Posts: n/a
I'm conducting simulaion for enclosed geometry (triangular) natural convection. It is for low Gr numbers, of Gr~1e5 (at least I call it low). I'm recreating somebody elses results and have had success with the solving using segeregated solver with the solution converging with a high number of iterations of a FEW thousand.

However when I use a coupled solver it diverges badly within the first hundered iteration even with a very small Courant number of 0.1, then slowly it converges over the next few thousand iterations, but nowhere near the speed with which the segerated solver converges.

This is confsing as the manual says that a coupled solver converges quicker.

Other points: using the exact same model composed of 7330 quad triangular elements.

thanks in advance

Allan
  Reply With Quote

Old   August 1, 2004, 23:19
Default adding species equation in Euler model
  #2
sunny
Guest
 
Posts: n/a
Hi,Everybody: I want to model air, propane vapor and propane liquid mixing. This problem includes three material so I want using the Euler model .But in Fluent Euler model regard the second phase (expct for the first phase ) as droplet ,but my second phase (propane vapor)is continous phase. I must add the species equation to fluent using udf. Now I can't find a Macros to connect different matrial .

Anyone have idea or experience in writing udf about speiecs equation . Help me

thanks in advance sunny
  Reply With Quote

Old   August 2, 2004, 05:25
Default Re: adding species equation in Euler model
  #3
Karthick
Guest
 
Posts: n/a
Dear sunny

I am also facing the same problem. But as per my knowledge, you cannot integrate the species transport and Eulerian model in Fluent. If you find any useful solution to this problem may be through udf, you please forward it to me.

Regards Karthick
  Reply With Quote

Old   August 2, 2004, 06:48
Default Re: Coupled Solver issues
  #4
prasanth
Guest
 
Posts: n/a
Dear Allan

Coupled solver will take more time than segragated solver for each individual iteration becuase it has to solve all equations simultaneously unlike segragated solver where equations are solved sequentially. Moreover its fine that you are getting convergence. normally people face convergence problem with the coupled solver in the wanting situations!!

thanks and regards Prasanth
  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
coupled solver wont work in star ccm+ richie CD-adapco 5 November 4, 2008 05:51
The seperated solver and coupled one summer FLUENT 0 July 5, 2006 15:06
can use coupled solver to calculate combustion cfdfans FLUENT 0 November 25, 2003 05:48
coupled solver / uncoupled solver Jaan Unger Main CFD Forum 0 September 3, 2002 08:30
Re: Coupled solver + RNG K-e Model JN FLUENT 1 April 22, 2001 16:34


All times are GMT -4. The time now is 21:33.