Radiation in Absorbing-Scattering Media Theory
The Radiation in Absorbing-Scattering Media Interface is available in 2D, 2D axisymmetric, and 3D components to model the propagation, attenuation, and scattering of an incident light within a semitransparent material considered to be nonemitting.
The radiative intensity I(Ω) at a given position following the Ω direction is the solution of the radiative transfer equation with no emission term (see Ref. 23):
(4-131)
where
κ, β, σs are absorption, extinction, and scattering coefficients, respectively (SI unit: 1/m) and are related by:
ϕ(Ω′, Ω) is the scattering phase function (SI unit: 1)
See Radiative Transfer Equation for details about the phase function, ϕ(Ω′, Ω).
The incident radiation, denoted G (SI unit: W/m2), is defined by
If the Discrete Ordinates Method (DOM) is used for the approximation of Equation 4-131, G is computed as
and
where
Si is the ith discrete ordinate.
Ii is the ith component of the radiative intensity.
ωj is the ith quadrature weight.
If the P1 Approximation Theory is used instead, G is the solution of the following equation,
(4-132),
with the following boundary condition for an opaque surface,
,
where DP1 is the P1 diffusion coefficient and ε the surface emissivity.