Date of Award

8-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Tallapragada, Phanindra

Committee Member

Kung, Ethan

Committee Member

Porter, Michael M

Abstract

Dynamics of inertial particles differ significantly from that of the underlying fluid flow. This difference in the dynamics of Inertial particles from that of fluid tracers can be exploited to segregate particles by size. While external forces can be used to manipulate the dynamics of such particles, using hydrodynamic forces which are always present in the flows of interest to manipulate inertial particle dynamics offers several advantages. Vorticity is one such phenomenon that is frequently encountered in natural and industrial flows. Thus, the dynamics of inertial particles have been studied in the presence of simple vortex flow configurations in this work, with the aim of gaining better insight into the problem of achieving size based segregation in the presence of vortex flow fields. In the first problem that has been investigated, the dynamics of inertial particles with varying stokes numbers have been studied in a four vortex flow configuration. After stating criteria to ensure that the particles have non-trivial dynamics, the criteria has been used to separate heavy particles from light particles using an array of vortices. The second problem studied is that of particle focusing in microfluidic channels. It is well known that inertial particles in the presence of hydrodynamic forces in microfluidic channel flows, focus into thin bands which can be used to achieve size based separation of such particles. One such force is the force exerted by dean vortices that form in flows through curved micro channels. In this study, we seek to computationally demonstrate that at low Reynolds numbers, particles with higher stokes number tend to cluster around the dean vortices, and thus leading to focused bands in the flow, while lighter particles are dispersed in the channel. While there exists two well established criteria to identify regions in phase space which permit inertial particles to lose their relative velocities and settle down, we introduce a third criteria to identify regions of the four dimensional phase space comprising of two dimensional space and the components of relative velocity in each of the two dimensions, within which the relative velocity of inertial particles may decay with time.

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