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On the peculiar structure of a helical wake vortex behind an inclined prolate spheroid

Published online by Cambridge University Press:  19 July 2016

Fengjian Jiang Open the ORCID record for Fengjian Jiang [Opens in a new window] ,
Helge I. Andersson ,
José P. Gallardo  and
Valery L. Okulov
Fengjian Jiang*
Affiliation:
Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway Huazhong University of Science and Technology, 430074 Wuhan, PR China
Helge I. Andersson
Affiliation:
Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
José P. Gallardo
Affiliation:
Department of Marine Technology, NTNU, 7491 Trondheim, Norway
Valery L. Okulov
Affiliation:
Department of Wind Energy, Technical University of Denmark, 2800 Lyngby, Denmark Institute of Thermophysics, SB of RAS, 630090 Novosibirsk, Russia
*
†Email address for correspondence: [email protected]
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Abstract

The self-similarity law for axisymmetric wakes has for the first time been examined and verified in a complex helical vortex in the far part of an asymmetric wake by means of direct numerical simulation (DNS). The helical vortex is the main coherent flow structure in the transitional non-axisymmetric wake behind an inclined 6:1 prolate spheroid at Reynolds number 3000 based on the minor axis. The gradual development of the complex helical vortex structure has been described in detail all the way from its inception at the spheroid and into the far wake. We observed a complex vortex composition in the generation stage, a rare jet-like wake pattern in the near wake and an abrupt change of helical symmetry in the vortex core without an accompanying change in flow topology, i.e. with no recirculation bubble.

JFM classification

Wakes/Jets: Separated flows Vortex Flows: Vortex Flows Wakes/Jets: Wakes
Type
Papers
Information
Journal of Fluid Mechanics , Volume 801 , 25 August 2016 , pp. 1 - 12
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Copyright
© 2016 Cambridge University Press 

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