| This thesis contains three parts covering gas-liquid-solid flows in three---phase slurry reactors, particle removal in turbulent flows and particle resuspension and transport due to indoor human walking.;In Chapter 2, An Eulerian-Lagrangian computational model for simulations of gas-liquid-solid flows in three---phase slurry reactors is developed. In this approach, the liquid flow is modeled using a volume-averaged system of governing equations, whereas motions of bubbles and particles are evaluated by Lagrangian trajectory analysis procedure. It is assumed that the bubbles remain spherical and their shape variations are neglected. The two-way interactions between bubble-liquid and particle-liquid are included in the analysis.;In Chapter 3, Three phase liquid-gas-solid flows under microgravity condition is studied. The transient flow characteristics of the three-phase flow were studied and the effects of gravity, inlet bubble size and G-jitter acceleration on variation of flow characteristics were discussed. The low gravity simulations showed that most bubbles are aggregated in the inlet region. Also under microgravity condition, bubbles transient time is much longer than that in normal gravity. As a result, the Sauter mean bubble diameter, which is proportional to the transient time of the bubbles, become rather large reaches to more than 9 mm.;In Chapter 4, Numerical simulations of gas-liquid-solid flows in different gravity were performed. The transient flow characteristics of the three-phase flow under different gravity were studied and the effects of gravity variation were discussed.;In Chapter 1, a general introduction to different sections of this thesis is presented and the objectives of the study are discussed.;In Chapter 5, a new rolling detachment model for particle removal in the presence of capillary forces based on the maximum adhesion resistance is developed. The new model uses an effective thermodynamic work of adhesion model that includes the effects of capillary forces generated by the formation of liquid meniscus at the interface. The JKR and DMT models for elastic particle and surface deformations and the Maugis and Pollock model for the plastic deformation are extended to include the effect of capillary forces.;In Chapter 6, rolling detachment of particles from surfaces in the presence of electrostatic and capillary forces based on the maximum adhesion resistance was studied. The critical shear velocities for removal of particles of different sizes were evaluated and the results were compared with those without electrostatic and capillary forces. The results were compared with the available experimental data and good agreement was obtained.;In Chapter 7, particle resuspension and transport due to indoor human walking are studied numerically and experimentally. The stepping motions of the foot, down and up, are modeled using a combination of two effective circular disks. The simulation results show that shoe bottom roughness, foot size, walking velocity, background velocity as well as the foot stepping velocities, down and up, affect particle resuspension rate from the floor and the corresponding particle concentrations in the indoor environment. (Abstract shortened by UMI.);Keywords. Numerical simulation, three phase flows, particle adhesion, particle detachment, particle resuspension, human walking... |
