Investigations in Gas-Solid Multiphase Flows

Abstract

Gas-solid multiphase flows are used extensively in both science and industry. Understanding these flows is great commercial and academic interest. One tool use to further our understanding of solid-gas flows is theoretical and computer modeling. One of the least understood areas of multiphase flows is the momentum transfer or coupling of the phases. Depending on the nature of the flow, such momentum transfer can have substantial effect on the flow. In this thesis, we investigate two novel and interesting aspects of momentum exchange in gas-solid multiphase flows. Until recently, Euler-Lagrangian techniques were only applied to dilute solid-gas flows, because of the computational expense required to calculate the particle-particle interactions. The first investigation in this thesis deals with extending the Euler-Lagrangian to dense solid-gas flows and the modifications required to make this technique a viable alternative to continuum techniques. The results of the various simulation and comparisons are presented and in general are in very good agreement with experimental data; capturing unique and previous unreported experimental features. In the second investigation, we apply inverse parameter estimation to the problem of determining the coefficients of an generalized Ergun type momentum exchange. The results of the investigation indicate that for flows under consideration, the momentum exchange term has small influence on the flow. This would also explain many of the results reported in the literature which use simplistic or physically unrealistic momentum exchange.