Radiative heat transfer in participating media

Summary

A participating medium is a material that absorbs, emits and scatters thermal radiation along the path of a ray. Examples are a combustion gas, a cloud of soot and a semitransparent solid. Radiative heat transfer in such a medium is governed by the radiative transfer equation for the spectral intensity at each point and in each direction. The divergence of the resulting radiative heat flux enters the energy equation of the medium. It matters in furnaces, flames, glass manufacture, the atmosphere and stars.