Doctor of Philosophy (PhD)
A parallel discrete particle modelling framework (PAR_DPM3D) is applied to study three fundamental multiphase flow problems: The sedimentation of a cluster of particles in a viscous ambient fluid, multiphase flow in a bench-scale fluidized bed and granular segregation and mixing dynamics in a rotating drum. Various phenomena including torus formation and particle cluster breakup are reproduced. We provide new insights into the volume fraction dependence of the dynamic characteristics of a settling particle cluster and find a similar dependence in the simulations as in the theoretical predictions of Nitsche and Batchelor 1. Similarities in the interaction between a system of two particle clouds and a system of two immiscible droplets was established with an observed increase in the velocity of the trailing cloud due to drag reduction in the wake of the leading cloud. Second, we show how existing drag models may be inadequate to predicting the macroscale properties of a gas-solid fluidized bed. Using an energy and force balance approach we provide new closures that account for some inhomogeneous flow structures and implement these closures within the PAR_DPM3D framework to predicting the axial pressure drop and transverse particle velocity profiles Finally, we present results from particle dynamics simulation of “S+D” granular systems (where size and density drive segregation simultaneously) in various irregular shaped tumblers in the rolling regime (10-4 < Fr < 10-2). We develop a new way of quantifying the state of mixing or segregation has been developed. Using this new measure of segregation (or entropy of mixing) we compare segregation dynamics for different shapes of tumblers.
Document Availability at the Time of Submission
Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.
Ayeni, Oladapo Olanrewaju, "Application of Discrete Element Method and Computational Fluid Dynamics to Selected Dispersed Phase Flow Problems" (2015). LSU Doctoral Dissertations. 3069.