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

Question about Absorption coeff.

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 7, 2001, 05:02
Default Question about Absorption coeff.
  #1
passer-by
Guest
 
Posts: n/a
Did anybody experience radiation? I'm suffering from finding a value of O2 absoption coefficient. Temperature range is roughly between 1400K and 2000K.

Since I'm a novice in radiation, it's not easy to find proper references. Can anyone suggest? Anything will be appreciated.
  Reply With Quote

Old   August 7, 2001, 06:57
Default Re: Question about Absorption coeff.
  #2
Jin-Wook LEE
Guest
 
Posts: n/a
Theoretically, pure O2 can not absorb radiation energy. So, theoretically, the absorbtion coefficient of O2 is zero. One of my friend uses 0.01(m^-1) or less value when he is interested in the solid(surface) radiation with air as gas phase material because he wants to include the effect of small amount of radiating material, such as CO2 and H2O, in the air. Actually, there is 1~2%(volume fraction) H2O in the air according to the humidity, and some CO2.

Sincerely, Jinwook
  Reply With Quote

Old   August 7, 2001, 08:57
Default Re: Question about Absorption coeff.
  #3
passer-by
Guest
 
Posts: n/a
Thanks a lot for your answer. Can I ask you one more?

If a gas media in my system is only air, is it reasonable to set the absorption & scattering coeff. to zero value? As I know, composition of O2 in air is dominant and I don't have to induce an effect that your friend is interested in.

I just consider a surface radiation. I wonder what is your opinion. Thanks.

  Reply With Quote

Old   August 7, 2001, 21:06
Default Re: Question about Absorption coeff.
  #4
Jin-Wook LEE
Guest
 
Posts: n/a
This my personal opinion.

If I were you, I am going to set the absorption coefficient of air as zero or very small value, e.g., 1.e-05, and scattering coefficient as zero, for the gas(air) phase calculation. This is just trick to include radiation model to the heat transfer analysis for the radiating surface with non-absorbing gas phase.

Sincerely, Jinwook

  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
Unanswered question niklas OpenFOAM 2 July 31, 2013 16:03
A question of absorption coefficient units ljwbuaa Main CFD Forum 1 August 4, 2011 02:45
absorption coeff. for radiation yugo_wen STAR-CCM+ 0 June 1, 2010 10:25
Absorption Coefficient Mark FLUENT 2 March 31, 2004 12:55
Energy absorption/ reflection coeff/ Define_Adjust A8anato_psofimi FLUENT 0 February 18, 2004 08:01


All times are GMT -4. The time now is 17:19.