Issue
EPL
Volume 81, Number 6, March 2008
Article Number 64007
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/81/64007
Published online 06 March 2008
EPL, 81 (2008) 64007
DOI: 10.1209/0295-5075/81/64007

Frequency response of the wake of a flat plate

R. H. Hernández and M. Vial

LEAF-NL, Departamento de Ingeniería Mecánica, Universidad de Chile - Casilla 2777, Santiago, Chile


received 26 March 2007; accepted in final form 9 January 2008; published March 2008
published online 6 March 2008

Abstract
Experimental results on the temporal evolution of the wake of a flat plate submitted to an external harmonic mechanical forcing are presented. The system consists of a horizontally fixed flat plate with a small flap at the trailing edge, which performs small oscillations when forced by an external shaker. At low Reynolds number, and working with weak forcing amplitudes, frequency response results show strong evidence of a spatio-temporal resonance of the near wake. Harmonic content of the wake is found to be related to interfaces of organized flow structures under resonant conditions. Near the resonant forcing frequencies, drag reduction is observed. In addition, the wake flow was tested as a wave propagating media, where arbitrary signals, like discrete number of bursts, were successfully propagated. Hot wire measurements and flow imaging through light scattering from smoke particles using a rapid ccd camera, allowed to record the inner and outer structures of the forced wake.

PACS
47.15.-x - Laminar flows.
47.85.L- - Flow control.
47.20.-k - Flow instabilities.

© EPLA 2008