The radiative transfer equation (RTE) for an absorbing, emitting, and scattering medium at position in the direction is
|=||scattering direction vector|
|=||Stefan-Boltzmann constant (5.672 10 W/m -K )|
|=||radiation intensity, which depends on position ( and direction|
is the optical thickness or opacity of the medium. The refractive index is important when considering radiation in semi-transparent media. Figure 13.3.1 illustrates the process of radiative heat transfer.
The DTRM and the P-1, Rosseland, and DO radiation models require the absorption coefficient as input. and the scattering coefficient can be constants, and can also be a function of local concentrations of H O and CO , path length, and total pressure. FLUENT provides the weighted-sum-of-gray-gases model (WSGGM) for computation of a variable absorption coefficient. See Section 13.3.8 for details. The discrete ordinates implementation can model radiation in semi-transparent media. The refractive index of the medium must be provided as a part of the calculation for this type of problem. The Rosseland model also requires you to enter a refractive index, or use the default value of .