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arXiv · 2008.08933

Span effect on the turbulence nature of flow past a circular cylinder

Bernat Font·Gabriel D. Weymouth·Vinh-Tan Nguyen·Owen R. Tutty
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Abstract

Turbulent flow evolution and energy cascades are significantly different in two-dimensional (2D) and three-dimensional (3D) flows. Studies have investigated these differences in obstacle-free turbulent flows, but solid boundaries have an important impact on the cross-over between 3D to 2D turbulence dynamics. In this work, we investigate the span effect on the turbulence nature of flow past a circular cylinder at Re=10000. It is found that even for highly anisotropic geometries, 3D small-scale structures detach from the walls. Additionally, the natural large-scale rotation of the K\'arm\'an vortices rapidly two-dimensionalises those structures if the span is 50% of the diameter or less. We show this is linked to the span being shorter than the Mode B instability wavelength. The conflicting 3D small-scale structures and 2D K\'arm\'an vortices result in 2D and 3D turbulence dynamics which can coexist at certain locations of the wake depending on the domain geometric anisotropy.

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Bernat Font, Gabriel D. Weymouth, Vinh-Tan Nguyen, Owen R. Tutty. 2020-08-20. Span effect on the turbulence nature of flow past a circular cylinder. https://doi.org/10.1017/jfm.2019.637

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