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Physics of Fluids / Volume 18 / Issue 2 / BRIEF COMMUNICATIONS

Phys. Fluids 18, 028101 (2006); http://dx.doi.org/10.1063/1.2171193 (4 pages)

On the generation of a reverse von Kármán street for the controlled cylinder wake in the laminar regime

Michel Bergmann, Laurent Cordier, and Jean-Pierre Brancher

LEMTA, UMR 7563 (CNRS-INPL-UHP), ENSEM-2, avenue de la forêt de Haye, BP 160, 54504 Vandœuvre cedex, France

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(Received 19 July 2005; accepted 3 January 2006; published online 2 February 2006)

In this Brief Communication we are interested in the maximum mean drag reduction that can be achieved under rotary sinusoidal control for the circular cylinder wake in the laminar regime. For a Reynolds number equal to 200, we give numerical evidence that partial control restricted to an upstream part of the cylinder surface may considerably increase the effectiveness of the control. Indeed, a maximum value of relative mean drag reduction equal to 30% is obtained when applying a specific sinusoidal control to the whole cylinder, where up to 75% of reduction can be obtained when the same control law is applied only to a well-selected upstream part of the cylinder. This result suggests that a mean flow correction field with negative drag is observable for this controlled flow configuration. The significant thrust force that is locally generated in the near wake corresponds to a reverse von Kármán vortex street as commonly observed in fish-like locomotion or flapping wing flight. Finally, the energetic efficiency of the control is quantified by examining the power saving ratio: it is shown that our approach is energetically inefficient. However, it is also demonstrated that for this control scheme the improvement of the effectiveness generally occurs along with an improvement of the efficiency.

© 2006 American Institute of Physics

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KEYWORDS and PACS

Keywords

vortices, wakes, laminar flow, drag reduction, flow control, numerical analysis

PACS

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.2171193

PUBLICATION DATA

ISSN

1070-6631 (print)  
1089-7666 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

For access to fully linked references, you need to log in.
    B. Protas and A. Styczek, "Optimal rotary control of the cylinder wake in the laminar regime," Phys. Fluids 14, 2073 (2002)PHFLE6000014000007002073000001.

    M. Bergmann, L. Cordier, and J.-P. Brancher, "Optimal rotary control of the cylinder wake using proper orthogonal decomposition reduced-order model," Phys. Fluids 17, 097101 (2005)PHFLE6000017000009097101000001.

    B. Protas and J. Wesfreid, "Drag force in the open-loop control of the cylinder wake in the laminar regime," Phys. Fluids 14, 810 (2002)PHFLE6000014000002000810000001.


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