Radiative transfer in multi-component media
General derivation of radiative transfer equations (RTEs)
and the boundary conditions are obtained for multi-component media
with heterogeneities in the size limit of geometrical optics
by employing the volume averaging theory. Precise definitions of the
continuum-scale radiative properties are formulated while accounting
for the radiative interactions between the components at their
interfaces and inside the components. The derivations are applicable
to media containing both opaque and semitransparent components.
This theory is of fundamental importance to direct numerical
characterisation of heterogeneous media with large components,
for example by computed-tomography based Monte Carlo techniques.
Model multi-component medium with components in the size range of geometrical optics: discrete-scale representation (left) and equivalent continuum-scale representation (right).