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The nature of the vortical structures in the near wake of the Ahmed body

Venning, James and Lo Jacono, David and Burton, David and Thompson, Mark C. and Sheridan, John The nature of the vortical structures in the near wake of the Ahmed body. (2017) Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 231 (9). 1239-1244. ISSN 0954-4070

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Official URL: https://doi.org/10.1177/0954407017690683

Abstract

This study presents the results from high-spatial-resolution water-channel velocity-field measurements behind an Ahmed body with 25° rear slant angle. The Ahmed body represents a simplified generic model of a hatchback automobile that has been widely used to study near-wake flow dynamics. The results help clarify the unresolved question of whether the time-mean near-wake flow structure is topologically equivalent to a toroidal vortex or better described by a pair of horizontally aligned horseshoe vortices, with their legs pointing downstream. The velocimetry data presented allows the tracking of the vortical structures throughout the near wake through a set of orthogonal planes, as well as the measurement of their circulation. The spanwise vortices that form as the flow separates from the top and bottom rear edges are shown to tilt downstream at the sides of the body, while no evidence is found of a time-mean attached toroidal vortex, at least for the Reynolds number (based on the square root of the frontal area) of Re~30000 under consideration.

Item Type:Article
Additional Information:Thanks to SAGE publications. The definitive version is available at http://journals.sagepub.com/ The original PDF of the article can be found at http://journals.sagepub.com/doi/10.1177/0954407017690683
HAL Id:hal-01613104
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Monash University (AUSTRALIA)
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Funders:
ARC - CNRS
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Deposited On:09 Oct 2017 09:42

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