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Stability of an elliptical vortex in a time-dependent strain field

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Date Issued:
1992
Summary:
A theoretical study of the stability of two-dimensional elliptical vortices in a time-dependent, periodically varying external straining flow was conducted. The mean value of the oscillating straining flow was chosen so that the vortex would be stationary in the absence of fluctuations of the external field about the mean. If the frequency of straining is near to the natural frequency of the vortex for small-amplitude oscillations of the vortex core, so that the vortex is forced near its natural frequency, a resonance occurs such that the aspect ratio of the elliptical core boundary initially oscillates with an amplitude that increases linearly with time. After an initial period of growth, the aspect ratio will either follow a bounded limit cycle at large time or it will elongate exponentially with time. The nonlinear evolution of the vortex at large time is studied numerically, and distinct regions of behavior in the parameter space for the vortex are obtained.
Title: Stability of an elliptical vortex in a time-dependent strain field.
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Name(s): Marshall, Marilyn P.
Florida Atlantic University, Degree grantor
Dhanak, Manhar R., Thesis advisor
College of Engineering and Computer Science
Department of Ocean and Mechanical Engineering
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Issuance: monographic
Date Issued: 1992
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 71 p.
Language(s): English
Summary: A theoretical study of the stability of two-dimensional elliptical vortices in a time-dependent, periodically varying external straining flow was conducted. The mean value of the oscillating straining flow was chosen so that the vortex would be stationary in the absence of fluctuations of the external field about the mean. If the frequency of straining is near to the natural frequency of the vortex for small-amplitude oscillations of the vortex core, so that the vortex is forced near its natural frequency, a resonance occurs such that the aspect ratio of the elliptical core boundary initially oscillates with an amplitude that increases linearly with time. After an initial period of growth, the aspect ratio will either follow a bounded limit cycle at large time or it will elongate exponentially with time. The nonlinear evolution of the vortex at large time is studied numerically, and distinct regions of behavior in the parameter space for the vortex are obtained.
Identifier: 14817 (digitool), FADT14817 (IID), fau:11606 (fedora)
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): College of Engineering and Computer Science
Thesis (M.S.)--Florida Atlantic University, 1992.
Subject(s): Vortex--Motion
Fluid dynamics--Mathematical models
Held by: Florida Atlantic University Libraries
Persistent Link to This Record: http://purl.flvc.org/fcla/dt/14817
Sublocation: Digital Library
Use and Reproduction: Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Use and Reproduction: http://rightsstatements.org/vocab/InC/1.0/
Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.