Vortex Flows: The Dynamics of Shear Layers and Hill's Vortex

We study the dynamics of flows with concentrated vorticity by analyzing the nonlinear instability of free vortex layers and Hill's vortex. The evolution is calculated numerically employing the contour dynamics formulation. We show that the growth of small, monochromatic perturbations on unstable vortex layers leads to the development of elliptical vortices whose asymptotic behavior is a function of the initial layer thickness and the form of the perturbation. Subharmonic disturbances initiate an interaction between vortices which may result in coalescence of large vortices and orbiting motion of small vortices. The calculations provide a criterion for the minimum vortex size required for coalescence. This phenomenon explains the transition to stochastic behavior characteristic of turbulent flows.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Pozrikidis, Constantine

• Engineering, Chemical

Identifier

(UMI)AAI8711855

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/69777