Publication:
Unidirectional periodic flow about circular cylinders.

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Authors
Greenamyer, Richard Doyle
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Date of Issue
1973-06
Date
June 1973
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The instantaneous force acting on a circular cylinder immersed in a unidirectional periodic flow characterized by U = V + VA sin 2π ft was investigated. The total force was divided into three components consisting of a steady-state drag; an oscillating drag which is a function of the frequency parameter λ = fd/V ; and an inertial force v;hich is also a function of the frequency parameter. The three resistance coefficients associated with the force components, CD (0), CD(λ), and CM (λ) were calculated. It was found that the resistance coefficients are not materially affected by the free-stream oscillations whenever the frequency of the oscillation is lower than the natural frequency of the vortex shedding. However, when λ approaches the Strouhal frequency of vortex shedding, the inertia coefficient CM is significantly reduced, and likewise when λ approaches the value of twice the Strouhal number, CD (λ) is markedly reduced. In regions below this range, the inertial force becomes negligible and the total resistance could be represented accurately by the coefficients DC (0) and CD (λ) with CM fixed at its theoretical unseparated-flow value, 2.0.
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Thesis
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Department
Mechanical Engineering
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Approved for public release; distribution is unlimited.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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