Cross-bispectral analysis of a vibrating cylinder and its wake in low Reynolds number flow

Abstract

Cross-bispectral analysis is used to investigate the coupling between a slender vibrating cylinder and the velocity field in its wake at low Reynolds numbers [Re = O(10^2)]. The velocity field was characterized by a complicated power spectrum, with low frequency peaks as well as upper and lower side band peaks near the primary Strouhal frequency peak and its harmonics. Power spectral and cross-bispectral analyses indicate that the rich structure of the wake velocity power spectra is a direct consequence of the vibrating cylinder. The data suggest the cylinder is coupled to its wake in the sense that the cylinder vibrations introduce motions into the wake at the vibration frequency, and these motions interact nonlinearly within the wake to produce fluctuations at other frequencies. Cross-bispectral analysis isolates the interactions between cylinder vibrations and wake fluctuations.

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