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

Radiation modeling

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 12, 2010, 17:56
Default Radiation modeling
  #1
New Member
 
Eric
Join Date: Feb 2010
Posts: 13
Rep Power: 7
cloudnqh is on a distinguished road
Hello, I have a very basic question on the radiation modeling in fluent.

Suppose I have a solid body, and the surface is defined as convection and radiation BCs. The ambient temperature is fixed. Only heat conduction and radiation are modeled in this case. How can define the radiation BC in fluent? It seems that all models need to include fluid or semi-transparent solid region.

Thanks,

Eric
cloudnqh is offline   Reply With Quote

Old   February 13, 2010, 09:05
Smile
  #2
New Member
 
Mehr
Join Date: Feb 2010
Posts: 5
Rep Power: 7
caspian_mehr is on a distinguished road
You can find your best answer in fluent tutorial . Chapter 5
Modeling radiation and natural convection
You could find in:
http://my.fit.edu/itresources/manual.../tg/node67.htm
caspian_mehr is offline   Reply With Quote

Old   February 13, 2010, 09:06
Default
  #3
New Member
 
HP Kritzinger
Join Date: May 2009
Location: South Africa
Posts: 25
Rep Power: 8
mystic_cfd is on a distinguished road
Hi Eric,

If the surface is on the outside of the domain (a one-sided wall) you do not need to model radiation in the solver. You only need to consider the conduction.

the radiation models in the solver is for use when the heat is radiated inside the solution domain.

hope this helps.
mystic_cfd is offline   Reply With Quote

Old   February 14, 2010, 23:32
Default
  #4
New Member
 
Eric
Join Date: Feb 2010
Posts: 13
Rep Power: 7
cloudnqh is on a distinguished road
HP Kritzinger,

Yes, the surface is on the outside of the domain. The surfice is exposed to ambient with temperature much lower than the surface temperature. I believe the radiation is equivalent to nature convection based on my calculation. I want to include the radiation in the modeling. But I cannot find any way to do that in Fluent. Like what you said, the models in the solver are for use when the heat radiation is happened inside the domain, instead of the domain surface and ambient.

thanks anyway for your help!


If the surface is on the outside of the domain (a one-sided wall) you do not need to model radiation in the solver. You only need to consider the conduction.

the radiation models in the solver is for use when the heat is radiated inside the solution domain.

hope this helps.[/QUOTE]
cloudnqh is offline   Reply With Quote

Old   February 14, 2010, 23:34
Default
  #5
New Member
 
Eric
Join Date: Feb 2010
Posts: 13
Rep Power: 7
cloudnqh is on a distinguished road
Mehr,

Thanks a lot. I was aware of the tutorial (Chapter 5). But it seems that all models are only used inside the domain, instead of the surfice (and ambient).

THanks,

Qihong

Quote:
Originally Posted by caspian_mehr View Post
You can find your best answer in fluent tutorial . Chapter 5
Modeling radiation and natural convection
You could find in:
http://my.fit.edu/itresources/manual.../tg/node67.htm
cloudnqh is offline   Reply With Quote

Old   February 15, 2010, 03:12
Default
  #6
New Member
 
HP Kritzinger
Join Date: May 2009
Location: South Africa
Posts: 25
Rep Power: 8
mystic_cfd is on a distinguished road
If I understand correctly, all you need is to change the wall to a mixed type in the GUI panel. On the wall boundary conditions window, under the Thermal tab, Select "Mixed" under Thermal Conditions. This gives you the option to specify both radiation and convection on a exterior surface.

regards
mystic_cfd is offline   Reply With Quote

Old   February 15, 2010, 10:06
Default
  #7
New Member
 
Eric
Join Date: Feb 2010
Posts: 13
Rep Power: 7
cloudnqh is on a distinguished road
Mystic_cfd,

Thanks a lot! I tried it before but it seems that the radiation flux will be zero when I do the post-processing. Should I turn on any radiation model in the solver?

Thanks,

Eric

Quote:
Originally Posted by mystic_cfd View Post
If I understand correctly, all you need is to change the wall to a mixed type in the GUI panel. On the wall boundary conditions window, under the Thermal tab, Select "Mixed" under Thermal Conditions. This gives you the option to specify both radiation and convection on a exterior surface.

regards
cloudnqh 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
Modeling Thermal Radiation Kaushik Saha FLUENT 0 September 17, 2008 19:12
Radiation Modeling Raju CFX 0 July 5, 2005 05:50
Question about Radiation Modeling Zhengcai Ye FLUENT 0 October 12, 2004 18:44
Radiation modeling in CFX 5 vortex CFX 2 August 26, 2002 16:13
Benchmark example for 3D radiation modeling! Klaus-Peter Helbig Main CFD Forum 3 October 25, 1999 02:40


All times are GMT -4. The time now is 07:00.