Analytical and numerical methods for the scattering by dense media

The study of the electromagnetic wave scattering from densely packed particles has applications in geoscience problems. For example, terrain snow consists of ice grains densely packed together, and foam on the ocean surface consists of densely packed air bubbles coated with a thin layer of water. Analytical and numerical methods have been applied to calculate the scattering and emission from such media. The analytical methods include the quasicrystalline approximation (QCA), the quasicrystalline approximation with coherent potential (QCA-CP) and dense media radiative transfer theory (DMRT). On the other hand, the Monte Carlo simulations use an exact numerical formulation based on the Foldy-Lax multiple scattering equations of 3D Maxwell´s equations. The authors computed the coherent and the incoherent field arising from scattering and absorption in systems of thousands of particles and up to fractional volume of 40%. In the past, they did simulations for small particles and small non-spherical particles. They present Monte Carlo simulations for moderate size particles (ka⩾1). The effect of the scatter placements on the electromagnetic wave is investigated by modeling the adhesive character of the particles that causes them to clump together with a sticky-particle pair distribution function. The adhesive character can provide a more accurate depiction of particles that exist in clusters (for example snow grains, air bubbles in ocean). To generate the positions for sticky particles in Monte Carlo simulation, the shuffling method is used and the tri-bond case is included