Reactive flow control for a wake flow based on a reduced model

Document Type

Conference Proceeding

Publication Date

1-1-2000

Abstract

As it is well known, the flow past a cylinder consists of a symmetric recirculation bubble of vortices at small Reynolds numbers. As Reynolds number increases, the bubble becomes unstable and develops into a Karman vortex street of alternating vortices. This instability is responsible for the occurrence of large amplitude oscillations in the lift and an increase in the mean drag. It was previously shown by numerical simulation that the mechanism driving the bubble instability is well mimicked by Föppl's four dimensional potential flow model where the bubble is represented by a saddle point1,2. In this work, we design an active feedback control algorithm for the model based on small forced vertical motions of the cylinder in order to control the flow slightly perturbed away from the fixed point so that the lift remain zero at all times. We use the domain perturbation method and asymptotic expansions to derive a feedback loop control algorithm analytically. We also show by direct numerical simulation of the flow based on the full Navier-Stokes equations that our feedback control system is capable of keeping the lift close to zero in the impulsively started viscous flow at Reynolds number Re = 100. © 2000 by the American Institute of Aeronautics and Astronautics, Inc. All rights Reserved.

Identifier

85087594886 (Scopus)

Publication Title

Fluids 2000 Conference and Exhibit

External Full Text Location

https://doi.org/10.2514/6.2000-2531

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