Doctor of Philosophy (PhD)
Multiphase modeling is prevalent and useful in solving problems involving multiphase interactions such as fluid and solid. Applications conclude but not limited to fluidized bed, hydraulic conveying, and many others. Modeling techniques with multiple scales can provide various states of details with diverse computational resources used. In this dissertation, two CFD multiphase models are used to disclose interaction details in the particulate system. Two-Fluid Model is used to solve pulsed fluidized bed problem and immersed boundary method based direct numerical method is used to solve particle’s behavior in shear flow. Getting a better understanding of these problems to help to provide adequate validation to these modeling methods and also can help predict and extend the modeling work to where experimental work is confined.
The study of pulsed fluidized bed explores the capabilities of Two-Fluid Models (TFM), with a variety of frictional closure models to reproduce the alternating bubble patterns in sinusoidal pulsed fluidized bed. Characteristics of pulsed fluidized bed such as the periodic formation of bubbles, horizontal alignment of bubbles during forcing cycles, and the alternation of bubble positions were successfully simulated. It is inferred that the selection of appropriate TFM models is critical in predicting correct flow patterns and hence, in exploring the optimization of the pulsed fluidized bed operations for industrial applications.
The study of cylindrical particle and elliptical particle in shear flow are performed with state of the art DNS method. A series of simulations are conducted in a range of particle Reynolds number from 2.5 to 80 to get a better understanding of the interaction between fluid and solid and how different shape of particles behave differently in shear flow. The locking phenomenon for elliptical particle is welled studied with changing particle aspect ratio. Further, it serves as the validation of our in house SDFIBM model in granular systems.
Ding, Zhizhong, "Multiphase CFD Modeling in Particle-Laden Flows" (2019). LSU Doctoral Dissertations. 5032.