Imperfect supercritical bifurcation in a three-dimensional turbulent wake

Olivier Cadot, Antoine Evrard, and Luc Pastur
Phys. Rev. E 91, 063005 – Published 12 June 2015
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Abstract

The turbulent wake of a square-back body exhibits a strong bimodal behavior. The wake randomly undergoes symmetry-breaking reversals between two mirror asymmetric steady modes [reflectional symmetry-breaking (RSB) modes]. The characteristic time for reversals is about 2 or 3 orders of magnitude larger than the natural time for vortex shedding. Studying the effects of the proximity of a ground wall together with the Reynolds number, it is shown that the bimodal behavior is the result of an imperfect pitchfork bifurcation. The RSB modes correspond to the two stable bifurcated branches resulting from an instability of the stable symmetric wake. An attempt to stabilize the unstable symmetric wake is investigated using a passive control technique. Although the controlled wake still exhibits strong fluctuations, the bimodal behavior is suppressed and the drag reduced. This promising experiment indicates the possible existence of an unstable solution branch corresponding to a reflectional symmetry preserved (RSP) mode. This work is encouraging to develop a control strategy based on a stabilization of this RSP mode to reduce mean drag and lateral force fluctuations.

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  • Received 9 February 2015
  • Revised 15 April 2015

DOI:https://doi.org/10.1103/PhysRevE.91.063005

©2015 American Physical Society

Authors & Affiliations

Olivier Cadot and Antoine Evrard

  • IMSIA-ENSTA ParisTech, CNRS, CEA, EDF, Université Paris-Saclay, 91762 Palaiseau cedex, France

Luc Pastur

  • LIMSI-Univ Paris Sud, CNRS, Université Paris-Saclay, 91403 Orsay cedex, France

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Issue

Vol. 91, Iss. 6 — June 2015

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