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dani January 18, 2001 16:43

models of radiation
 
that radiation model which has fluent determines the radiation between surfaces considering the form factor? apparently single gas radiation is had and the radiation for surfaces is not considered

thanks


Raza Mirza January 18, 2001 19:27

Re: models of radiation
 
Dani,

I think Fluent does not have surface-to-surface radiation model (that's how I have heard people refer to it) which makes use of form factors. I think fluent offers Discrete Transfer Radiation Model (DTRM) and Discrete Ordinate Method (DOM). I am not familiar with the former, but the later is a volumetric radition model which solves for radiation engery transfer though the volume cells, tracking engery in a fixed number of ordinate directions. I believe it does not need form factor, but will account for raditation off of the bounding surfaces.

May I ask what are you trying to model?

dani January 19, 2001 08:28

Re: models of radiation
 
I am working in the model of the heat transference in a room, which has a window, a frame and a card that the effect of a curtain simulates and that this to a distance of X mm of the frame, soon I need to apply radiation to the model since between the window and the curtain the main means of heat transference are by radiation, and the curtain is like a radiativa screen, by this I need to know the radiation the curtain with the walls that surround it, and with the window, the model P1 de Fluent is the unico that allows me to place the respective emisividades of each surface, by this in the correct thing and it is possible to be occupied... you can help me with some idea?

Raza Mirza January 25, 2001 20:33

Re: models of radiation
 
Hi,

I hope by now you have already solved your problem. But in case you still need help, let me say a few things.

1. In automotive applications, a problem similar to yours often arrives when looking at the heat transfer in the underbody. There a radiation shield is placed between the hot exhaust pipe and the surrounding parts that need to be shielded from the heat. The mechanism of heat transfer is largely radiation, although in this case convection effect is also present.

2. This radtiation shield is typically modeled as a baffle (zero thickness for flow, but assigned a thickness for condution). I guess you are also trying to model it as a baffle.

3. Although I have not used it myself, one of the fluent's engineer suggested using discrete ordinate method for the automotive underbody case. I have also seen an example of such an application at Fluent's 2000 Automotive User Group meeting in Novi, Michigan.



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