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A study of two-dimensional flow past an oscillating cylinder
In this paper we describe a detailed study of the wake structures and flow dynamics associated with simulated two-dimensional flows past a circular cylinder that is either stationary or in simple harmonic cross-flow oscillation. Results are examined for Re=500 and a fixed motion amplitude of ymax/D=...
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Published in: | Journal of fluid mechanics 1999-04, Vol.385, p.255-286 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | In this paper we describe a detailed study of the wake structures and flow dynamics
associated with simulated two-dimensional flows past a circular cylinder that is either
stationary or in simple harmonic cross-flow oscillation. Results are examined for
Re=500 and a fixed motion amplitude of ymax/D=0.25.
The study concentrates
on a domain of oscillation frequencies near the natural shedding frequency of the
fixed cylinder. In addition to the change in phase of vortex shedding with respect
to cylinder motion observed in previous experimental studies, we note a central
band of frequencies for which the wake exhibits long-time-scale relaxation oscillator
behaviour. Time-periodic states with asymmetric wake structures and non-zero mean
lift were also observed for oscillation frequencies near the lower edge of the relaxation
oscillator band. In this regime we compute a number of bifurcations between different
wake configurations and show that the flow state is not a unique function of the
oscillation frequency. Results are interpreted using an analysis of vorticity generation
and transport in the base region of the cylinder. We suggest that the dynamics of
the change in phase of shedding arise from a competition between two different
mechanisms of vorticity production. |
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ISSN: | 0022-1120 1469-7645 |
DOI: | 10.1017/S0022112099004309 |