Wave Propagation In Inhomogeneous Media Containing Randomly Oriented Nonspherical Scatterers

Abstract

When waves propagate in a medium containing a random distribution of randomly oriented nonspherical scatterers, the attenuation and the dispersion are independent of the direction of propagation due to the fact that the scattering medium is macroscopically or on the average isotropic. But, in many cases, the non-spherical particles are aligned, rendering the random medium effectively anisotropic. Previous approaches to the problem, depending on the concentration of scatterers, used either single scattering theory (an extension of Mie theory for a single scatterer) or multiple scattering theory by assuming spherical statistics for describing the spatial distribution of even nonspherical scatterers. Approximating the spatial distribution of aligned nonspherical scatterers using spherical statics will yield very different results which has been, recently, shown by the authors. In this paper, we wish to discuss the isotropic properties of randomly oriented nonspherical scatterers with a considerable concentration. In collaboration with Professor William A. Steele of Chemistry Department at Penn State, we have generated by Monte Carlo simulation the pair correlation function for randomly oriented spheroidal particles as a function of the their separation distance and the relative azimuthal and polar angles. The randomly oriented case is more complicated than that for the aligned one. The pair correlation function is then incorporated into the multiple scattering calculations and compared with those using spherical statistics. Numerical results are presented for the attenuation of electromagnetic waves versus freqency and concentration.