[alexksei]

Hi everyone,

My sumulation is as follows:

1. I've got enclosed air domain with initial temperature around 35 C with several hot solid bodies inside the space with temperatures up to 700 C

2. In that domain there is also a solid domain, inside which there is water domain.

I'd like to know which radiation model(s) I need to use in those domains.
Please have a look at a picture for clarification.

My final objective is to get the tempereature distribution in water and air domain.

[ghorrocks]

The choice of radiation model depends on the radiation conditions. There are several models available for optically thick mediums, and only two available for optically transparent media (Monte Carlo and Discrete transfer). Read the documentation about the assumptions behind these models to determine which is most suitable for you.

[alexksei]

Originally Posted by ghorrocks

The choice of radiation model depends on the radiation conditions. There are several models available for optically thick mediums, and only two available for optically transparent media (Monte Carlo and Discrete transfer). Read the documentation about the assumptions behind these models to determine which is most suitable for you.

Thank you for your reply.

I went through the documenataion of CFX quite carefully.
I understand that air is considered as optically thin -> Monte Carlo / Discrete Transfer should be used.

As for solid domain - the only available option is Monte Carlo for solids.

I still can't understand if water is considered as optically thick or optically thin.

[ghorrocks]

Solid domain - you only use a radiation model here if radiation does something. Radiation will only do something if it is transparent. If it is opaque then don't use a radiation model in the solid domain. The effects of the radiation on the surrounding fluid domain acts on the interface between the domains.

Whether water is optically thick or thin depends on how far a typical photon will get before it is absorbed. If a photon would typically reach a surface or penetrate a long way into the fluid then it is optically thin and you should use the Monte Carlo or Discrete Transfer approaches. If a typical photon will only go a short way before being absorbed then use the simpler radiation models.