Diffuse optical process tomography in multiphase flows: Simulation of light propagation and image reconstruction

The finite element method (FEM) is used for the simulation of optical process tomography as applied to multiphase flows. Comsol Multiphysics™, which is a powerful interactive code for solving scientific and engineering problems and based on partial differential equations, is used for studying the forward diffuse optical tomography (DOT) problem. The radiative transfer equation (RTE) and its diffusion approximation were used for modeling light transmission through multiphase flow medium. The primary objective of this thesis is to implement RTE for various single and multiple bubble situations as part of an effort to imitate gas bubbles in a bubble column reactor. Light transmission data obtained from DOT simulations using TOAST, a software code for solving DOT problem, is used as the basis for reconstruction of the internal multiphase flow structure for comparison to the actual flow structure. The results from this work will provide the basis for determining the utility of DOT as a tool for analyzing the hydrodynamic characteristics of multiphase flows and the basis for design of a robust experimental system for the same.