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

Model with Thermal radiation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 14, 2012, 09:19
Default Model with Thermal radiation
  #1
Senior Member
 
Roland Rakos
Join Date: Mar 2009
Posts: 120
Rep Power: 8
Roland R is on a distinguished road
Hello,

I would like to calculate a steady state simulation with fluid and solid domains. The temperature is quite high in the solids (300-400C) therefore the thermal radiation is important.

I experiment with a simple 2D modell. Firstly I made the modell without thermal radiation. Finally I added the thermal radiation to the model and it was initialized from the previous result. The first model run very fast but the second one (with thermal radiation) is very very slow.

Why does the modell become so difficult with thermal radiation?

The values of parameters (in terms of thermal radiation) are default, I didnít change it. I use the Monte Carlo model, and the Surface to surface option. Is it correct to solve this problem?

Thanks a lot
Roland
Roland R is offline   Reply With Quote

Old   June 14, 2012, 19:07
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,646
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Mone Carlo radiation simulation is often slow as it is very computationally intensive. If the fluid does not interact with the radiation much (ie radiation just causes surface to surface heat transfer) consider the Discrete Transfer model, it is much faster.
ghorrocks is offline   Reply With Quote

Old   June 15, 2012, 05:52
Default
  #3
Senior Member
 
Roland Rakos
Join Date: Mar 2009
Posts: 120
Rep Power: 8
Roland R is on a distinguished road
I complated a simple 3D model. There is a large air domain, and it contains two cylinders (with diameter 10cm). Material of the cylinders is steel. Distance between the cylinders is 1cm. Temperature of one of two cylinders is 400C. It was defined at the wall of cylinder. Velocity of air is 1m/s.

Based on result, temperature of second cylinder will be about 122-129C. I don't understand this. I think that the temperature of second cylinder should be more higher.

Which parameter can be incorrect (in case of thermal radiation)? (At the moment all parameters and settings are default.)

Thanks
Roland
Roland R is offline   Reply With Quote

Old   June 15, 2012, 06:57
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,646
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
If you are new to radiation modelling I strong recommend you do a simple model with an analytical answer (eg heat transfer between two parallel plates) to make sure you know how to get accurate answers in radiation modelling before trying to tackle a real problem.
ghorrocks is offline   Reply With Quote

Old   June 15, 2012, 06:59
Default
  #5
Senior Member
 
Roland Rakos
Join Date: Mar 2009
Posts: 120
Rep Power: 8
Roland R is on a distinguished road
Yes, this is a good idea
Roland R is offline   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
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
Thermal Radiation of a bulb Andy CFX 2 September 29, 2008 03:30
heat transfer with s2s radiation model in fluent D. L. FLUENT 3 July 31, 2008 07:40
DO radiation model jarno brunetti FLUENT 0 January 21, 2006 16:52
Solar radiation model Min CD-adapco 0 October 18, 2004 05:13


All times are GMT -4. The time now is 02:59.