Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov, O. and Busse, A. (2019) Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs. European Journal of Mechanics - B/Fluids, 75, pp. 244-257. (doi: 10.1016/j.euromechflu.2018.09.008)

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Abstract

The aerodynamic coefficients and the Strouhal number of cylinders with three and four ribs, inspired by succulents Euphorbia trigona and Euphorbia Abyssinica are investigated using 2D Unsteady Reynolds-Averaged Navier-Stokes simulations at Reynolds number 20,000. Both configurations show a significant dependence of the studied characteristics on the angle of attack. The obtained results are compared to the smooth circular cylinder, previous results for cylinders with 24 ribs based on the Saguaro cactus, and cylinders with triangular and square cross-sections. Relative to the circular cylinder, the mean drag coefficient is lowered only for the four-rib case at high angles of attack. However, at some angular positions, the ability to reduce unsteady force fluctuations exceeds Saguaro-inspired cylinders. For both shapes studied, the Strouhal number at most angles of attack is lower compared to both the circular cylinder and cylinders with 24 ribs at the same Reynolds number. The minimum values of the aerodynamic coefficients for both configurations are related to the angular orientation. For the four-rib case a critical angle of αcr ≈ 40◦ is observed, at which the mean drag coefficient and the fluctuating lift coefficient attain their minima. The mean lift coefficient reaches at this angle its maximum value before a sudden drop for higher angles of attack. Therefore, for cactus-shaped cylinders with four ribs high angles of attack give the optimum orientation relative to prevailing winds.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Busse, Dr Angela and Zhdanov, Dr Oleksandr
Authors: Zhdanov, O., and Busse, A.
College/School:College of Science and Engineering > School of Engineering
College of Science and Engineering > School of Engineering > Aerospace Sciences
Journal Name:European Journal of Mechanics - B/Fluids
Publisher:Elsevier
ISSN:0997-7546
ISSN (Online):1873-7390
Published Online:09 October 2018
Copyright Holders:Copyright © 2018 Elsevier Masson SAS
First Published:First published in European Journal of Mechanics - B/Fluids 75: 244-257
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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