A description is given of a practical approach for calculating emission from a source having cylindrical symmetry and containing both absorbing gases (not obeying Beer's law in general) and absorbing and scattering particles of arbitrary size distributions. Two levels of sophistication are described: (1) a two-flux solution which is obtained by direct path integration and (2) a six-flux solution which requires a prior solution of a reduced-size equation for an isotropic source term. A generalization of standard random gaseous band models is provided to include scattering by use of empirical forms.
"Practical Treatment Of Particle Plumes", Proc. SPIE 0253, Modern Utilization of Infrared Technology VI, (17 December 1980); doi: 10.1117/12.959505; https://doi.org/10.1117/12.959505