8.8 Radiation Properties

When you have activated one of the radiation models (except for the surface-to-surface model, which requires no additional properties), there will be additional properties for you to set in the Create/Edit Materials dialog box:

• For the P-1 model, you will need to set the radiation Absorption Coefficient and Scattering Coefficient ( $a$ and $\sigma_{s}$ in this equation in the separate Theory Guide).

• For the Rosseland radiation model, you will also need to set the Absorption Coefficient and Scattering Coefficient ( $a$ and $\sigma_{s}$ in this equation in the separate Theory Guide).

• For the DTRM, only the Absorption Coefficient is required ( $a$ in this equation in the separate Theory Guide).

• For the DO model, you will set both the Absorption Coefficient and the Scattering Coefficient ( $a$ and $\sigma_s$ in this equation in the separate Theory Guide). In addition, if you are modeling semi-transparent media, you can specify the Refractive Index ( $n_a$ or $n_b$ in this equation in the separate Theory Guide). Note that with the DO model, you can specify radiation properties for solid materials, to be used when semi-transparent media are modeled.

Information about defining each of these properties is provided in the following sections.