Gray Radiation
Hi,
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? Thanx Newbie |
Hi Community,
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. Questions are: 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, Sincerely, RSSLNT |
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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. Quote:
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". |
Thank you very much. Appreciate your interest in clarifying the doubt.
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Hi,
I am dealing with same radiation problem as yours. While doing radiation modelling by D.O. method. Can you tell me how should I proceed??? Thanks and regards. |
Some modelling to anlyze radiation case in fluent, how is better modelling to analyze furnace radiation?
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radiation model
Dear lucy tan, when you said about absoprtivity, is there refering to absoprtion of coeffiecient air? because when used the radiation model, i found the material properties of air need to insert in some value.
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I am modeling a 1070 nm laser beam, that focuses on a high-pressure Xenon gas volume. At a high enough temperature, the Xenon gas will absorb the laser radiation and generate temperature at the focusing point. I found that the DO model can set up the wavelength with non-gray model. I am curious that could I setup a laser beam in the Ansys Fluent? Please see my attached photo.https://www.cfd-online.com/Forums/at...1&d=1695012120 |
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