Radiation and interfaces
 

Hi everbody!

On a previous message (Re: radiation on interfaces

Posted By: Glenn Horrocks Date: Wed, 13 Apr 2005, 4:31 p.m. ) it can be read:

Therefore you use "conservative interface flux" at the fluid-solid interface for radiation when the solid is transparent and you model radiation; you set emissivity and diffuse fraction if the solid is opaque and you do not model radiation in it.

I want to simulate an opaque solid that interacts with a fluid.

But in CFX 5.7.1 when you try this, you can set emissivity on the "fluid-side" of the interface only (P1, DT or Montecarlo radiation models).

This sounds to me that a surface with the fluid temperature ('cause you set emissivity on the "fluid-side") is emitting.

But if the "fluid-side" of the interface has a temperature quite different than the "solid-side", this could not be correct.

You can set emissivity on the "solid-side" but you have to turn on radiation in the solid: this means it's no more opaque.

Any suggestions?

Thanks in advance!

Re: Radiation and interfaces
 

Hi,

You are assuming that the CFX solver implementation uses the conservative fluid temperature for the emission. Quite the contrary, the fluid side wall temperature is the same than the solid side. The conservative values on either side are different, but not the wall value.

Just set the boundary condition to Opaque and specify the Emissivity and Diffuse Fraction. You are set to go.

Good luck, Juan Carlos

Re: Radiation and interfaces
 

Hi Juan Carlos,

thank you very very much for your reply and your precious comment!