Interference effects on scattering by parallel fibers at normal incidence

This paper examines the radiative heat transfer through fibrous materials, focusing on the interactions between the scattered radiation from individual parallel fibers. A normally incident plane electromagnetic wave is considered, and different representative geometries are analyzed theoretically. Experimental results are presented for a specific case corresponding to fibers in one plane. The light-scattering characteristics of a single long fiber depend only on the size parameter and on the material optical constants. When multiple fibers are spaced closely together, the additional mechanism of interference between the scattered waves influences the scattering characteristics of the fiber assembly as a whole. Previous studies of radiative transport through fibrous media have ignored these effects. In this study analytical models are developed for obtaining the radiative scattering characteristics of fibrous media where the mechanism of interference is accounted for. The results indicate that interference decreases the scattering efficiency of fibrous media containing a large number of randomly positioned fibers. For other configurations the results are more complex. The predicted results are compared with experimental measurements of forward- and back-scattered light from a system of finite parallel fibers over a broad range of wavelengths.