Optimum-Wavelength Forcing Of A Bluff Body Wake

Abstract

Three-dimensional forcing of the wake of a circular cylinder was studied experimentally to determine the optimal spatial-forcing-wavelength for drag reduction. Dielectric-barrier-discharge plasma actuators were mounted on a cylinder in a square-wave pattern to create the three-dimensional forcing. Six spatial wavelengths (1d-6d) and two blowing ratios (Uj/U∞ = 0.2 and 0.6) were tested at a Reynolds number of 4700. For most spatial wavelengths and blowing ratios, the segmented plasma actuators produced streamwise vorticity that altered the wake development, formation length, and drag. A spatial wavelength of 4d emerged as the optimum wavelength for the high-blowing-ratio case. Forcing with this optimum wavelength significantly attenuated vortex shedding, leading to maximum drag reduction in the high-blowing-ratio case. This optimum wavelength of 4d exists because longer wavelengths reduce the spatial extent of induced velocity and shorter wavelengths inhibit the development of streamwise vorticity.

Publication Date

1-1-2018

Publication Title

Physics of Fluids

Volume

30

Issue

1

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1063/1.4999091

Socpus ID

85041384064 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85041384064

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