CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Is it possible to ignore conduction in a fluid zone?

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

LinkBack Thread Tools Display Modes
Old   August 11, 2011, 14:03
Default Is it possible to ignore conduction in a fluid zone?
New Member
Join Date: Jul 2010
Posts: 7
Rep Power: 9
bawfuls is on a distinguished road
I am using a UDF for this problem but my question isn't really about UDF functionality so I'm posting here.

I am modeling heat transfer and fluid flow in a high temperature participating medium, using a UDF and outside code for the radiation model. (The outside code computes radiation heat transfer and sends source terms to Fluent.)

For bench-marking purposes, I wish to model radiation heat transfer between parallel infinite plates with a participating medium between. However, the bench-mark should only include radiation heat transfer, and ignore conduction in the participating medium, i.e. the fluid. Since I am providing Fluent with a source term for the energy equation (via the UDF), is there a way to tell Fluent to ignore conduction completely? I tried setting thermal conductivity of the gas to 0, but that just gives an error (Divergence detected in the temperature solver.) If i set the thermal conductivity to anything non-zero, the steady state solution will eventually converge based on the conduction, and I won't have a good radiation bench-mark.

Why can't Fluent ignore conduction if I'm providing it a source term for the energy equation?
bawfuls is offline   Reply With Quote

Old   August 11, 2011, 15:37
Senior Member
Amir's Avatar
Join Date: May 2009
Location: Montreal, QC
Posts: 739
Blog Entries: 1
Rep Power: 16
Amir is on a distinguished road
I think it's not weird to face convergence issues by eliminating conduction term; as you know, this term has dissipative role and by eliminating of that, small instabilities can easily grow without any damping; this issue is more probable by introducing source terms, especially explicit ones.
Anyway, I think you may achieve convergence if you implement other dissipative schemes, such as second order upwind or reducing conductivity in some stages and also good initialization. Share your findings if you can solve this issue.


Last edited by Amir; August 11, 2011 at 16:01.
Amir is offline   Reply With Quote

Old   August 11, 2011, 16:50
Senior Member
Micael Boulet
Join Date: Mar 2009
Location: Quebec, Canada
Posts: 130
Rep Power: 11
Micael is on a distinguished road
Did you derivated the source term in respect to T? I mean, do you give any value for dS[eqn] ? That usually help stability.
Micael is offline   Reply With Quote

Old   August 11, 2011, 21:50
New Member
Join Date: Jul 2010
Posts: 7
Rep Power: 9
bawfuls is on a distinguished road
Thanks for the advice, I neglected to mention that I'm also specifying zero velocity for this benchmark, so that make the problem of dissipation worse.

However, I have since found a suitable benchmark that includes radiation and conduction, so for now I'm pursuing that method as it seems more appropriate for Fluent.
bawfuls is offline   Reply With Quote


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
StitchMesh on two patches anita OpenFOAM Native Meshers: blockMesh 31 April 4, 2013 11:51
TGridFluent mesh with internal by prism layer and internal face for diagnostic sponiar OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 2 March 30, 2009 15:02
Fluid Zone Source of Z Paul FLUENT 0 July 31, 2007 14:55
how to define a local zone in whole fluid zone? Lcw FLUENT 3 September 21, 2004 08:33
Sliding mesh error Karl Kevala FLUENT 4 February 21, 2001 16:52

All times are GMT -4. The time now is 02:20.