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The effect of porosity on the drag of cylinders

Steiros, K; Kokmanian, K; Bempedelis, N; Hultmark, M; (2020) The effect of porosity on the drag of cylinders. Journal of Fluid Mechanics , 901 , Article R2. 10.1017/jfm.2020.606. Green open access

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Abstract

It is well known that perforation of a flat plate reduces its drag when exposed to a flow. However, studies have shown an opposite effect in the case of cylinders. Such a counterintuitive result can have significant consequences on the momentum modelling often used for wind turbine performance predictions, where increased porosity is intrinsically linked to lower drag. Here, a study of the drag of various types of porous cylinders, bars and plates under steady laminar inflow is presented. It is shown that, for most cases, the drag decreases with increased porosity. Only special types of perforations can increase the drag on both cylinders and bars, either by enhancing the effect of the rear half of the models or by organizing the wake structures. These rare occurrences are not relevant to wind turbine modelling, which indicates that current momentum models exhibit the qualitatively correct behaviour.

Type: Article
Title: The effect of porosity on the drag of cylinders
Open access status: An open access version is available from UCL Discovery
DOI: 10.1017/jfm.2020.606
Publisher version: https://doi.org/10.1017/jfm.2020.606
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Wakes
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10115354
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