Investigation of Various Source Models in the Diffusion Approximation

Applications involving foams in industrial processes are widespread. Foams are encountered in enhanced oil recovery and drilling operations, in the production of cosmetics, in the production of food and in the development of new insulation and construction materials. Often the development of foam is a desired outcome. However, in applications such as glass melting or fermentation processes, foam layers act as barriers to heat and mass transfer, and the presence of foam is undesirable. Due to their widespread use and importance, techniques for characterizing foams are of interest. A technique known as diffusing-wave spectroscopy has shown promise as a method for determining the radiative properties of foam. Relationships between measurable quantities and the radiative properties of the foam are derived using the diffusion approximation to the radiative transfer equation. The objective of this paper is to investigate the use of various models for the source term in the diffusion approximation. The diffusion model is validated by comparison with a Monte Carlo simulation for one case.