Date of Award

12-2015

Degree Name

Master of Science in Engineering

Department

Chemical and Paper Engineering

First Advisor

Dr. Dewei Qi

Second Advisor

Dr. Said Abubakr

Third Advisor

Dr. James Springstead

Access Setting

Masters Thesis-Open Access

Abstract

This research is a thorough numerical investigation and critical analysis of lateral migration of a deformable particle settling in a vertical weak shear flow. Under the vertical weak shear fluid, the deformable particle may move either to the coagulation area, or the dispersion area, depending on Reynolds numbers, shear Reynolds number, fiber flexibility, and aspect ratio. In this study, a lattice Boltzmann equation is used to solve Navier-Stokes equation and a flexible particle method is employed to attack the problem of motion of a flexible fiber. A bounce-back rule is used to deal with moving boundaries interacting with fluids. Several simulations are first conducted at the same shear Reynolds number, particle settling Reynolds number and aspect ratio except that the rigidity is varied at different levels. It is found that the rigidity plays a critical role, may change particle lateral migration direction, either migrate toward a coagulation area, or toward a dispersion area, depending the value of the rigidity. It shows that the rigidity may alter the fiber inertia, in turn, convert coagulation to dispersion. In other words, flexibility may alter the stability of fiber suspension. At a low settling Reynolds number, as the vertical shear flow increases the fiber dispersion trend increases and the lower rigid fiber has a larger tendency to disperse.

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