title: Two-flux radiative transfer model under nonisotropic propagating diffuse radiation.
abstract: A two-flux model is considered as a particular case of a more-general four-flux approach to describing the properties of highly diffusing materials derived from the radiative transfer equation. Any degree of anisotropy is taken into account by means of average path-length parameters and forward-scattering ratios for diffuse radiation propagating in forward and backward directions. The conditions for applicability of the standard two-flux model of Kubelka and Munk are characterized in terms of particle size and refractive index as well as of optical thickness. Scattering and absorption coefficients are obtained in terms of the effective average path-length parameter and forward-scattering ratio of the propagating radiation as well as of the intrinsic scattering and absorption coefficients per unit length of the particulate medium.
authors.affiliation: Centro de Investigación en Ciencia e Ingeniería de Materiales and Escuela de Física, Universidad de Costa Rica, Box 2060, San José, Costa Rica.
authors.forename: W E
authors.initials: WE
authors.lastname: Vargas