|March 12, 2004, 08:20||
Can anyone give me a brief description of what gray radiation is and when should the discrete ordinates radiation model activate the non-gray model.
And is there a guideline for the number of bands that should be used if the gray modelling is necessary?
|December 20, 2012, 08:15||
Join Date: Jan 2012
Posts: 17Rep Power: 5
Requesting someone to shed light on a question that was previously asked. I am starting to learn radiation models in Fluent. While reading the user manual on Setting up of P-1 radiation model I came across the terms, "Non-gray model" and "Gray Model". If I increase the number of bands to any value greater than 0, it becomes a non-gray model which is expensive in terms of computation time.
What is the difference between non-gray and gray models OR Under what conditions would you go for a non-gray or a gray model?
How do you determine is a given problem can be considered as a gray radiation problem without losing significant accuracy.
Thanking you for sharing any thoughts or information,
|December 22, 2012, 03:39||
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 606Rep Power: 12
The gray model offers a huge simplification to real problems. The gray model should always be used first wherever possible. If more accurate solutions are desired, then it may be appropriate to use a non-gray model.
Some care should be exercised, because many media being considered nowadays have narrow emission bands in their intended operating conditions but very broadband emission at "normal conditions".
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