Active techniques to control vortex shedding

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Discussion Overview

The discussion focuses on active techniques for controlling or manipulating vortex shedding in the near wake behind 2D or axisymmetric bluff bodies, such as cylinders. Participants explore various methods and research related to this topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about available active techniques for controlling vortex shedding, indicating a need for information on this topic.
  • Another participant suggests looking into active flow control devices, specifically mentioning sparkjet or synthetic jet actuators as potential methods.
  • A participant references two specific papers that discuss active control methods: one involving Lorentz forces to manipulate wake flows and another utilizing rotary cylinder oscillations controlled by feedback signals to reduce vortex shedding.
  • A different participant expresses interest in identifying standard and common active techniques for controlling vortex shedding, comparing it to established methods for flow speed measurement.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on specific common active techniques for controlling vortex shedding, and multiple viewpoints regarding the effectiveness and types of methods remain present.

Contextual Notes

Participants have not yet established a definitive list of standard techniques, and the discussion includes references to specific research papers that may not be universally recognized or agreed upon.

ghost85
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I am doing a paper regarding active techniques to control/manipulate vortex shedding in the near wake behind a 2D or axisymmetric bluff body, such as cylinder.

May I know what are the available active techniques used in controlling vortex shedding?

Thank you.
 
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ghost85 said:
I am doing a paper regarding active techniques to control/manipulate vortex shedding in the near wake behind a 2D or axisymmetric bluff body, such as cylinder.

May I know what are the available active techniques used in controlling vortex shedding?

Thank you.

I would look into active flow control devices, sparkjet or synthetic jet actuators. Report back with anything of interest that you find.
 
Here's a couple I found quickly:

"Active Control of Cylinder Wake", Chen and Aubry, Communications in Nonlinear Science, 10(2005)

The objective of this paper is to develop an efficient active control algorithm for manipulating wake flows
past a solid cylinder in an electrically low-conducting fluid (e.g. seawater). The intent is to avoid both vortex
shedding and flow separation from the body. It is expected to reduce the mean drag significantly. This is
achieved through the introduction of a Lorentz force in the azimuthal direction generated by an array of
permanent magnets and electrodes located on the solid structure. With the use of a symmetric and static
Lorentz force over the entire surface of the cylinder, the vortex shedding behind the cylinder weakens and
eventually disappears completely when the Lorentz force is sufficiently large.


"FEEDBACK CONTROL OF VORTEX SHEDDING FROM A CIRCULAR CYLINDER BY ROTATIONAL OSCILLATIONS", Fujisawa, Kawaji, Ikemoto, Journal of Fluids and Structures (2001),15

The present paper describes a new active method for controlling vortex shedding from
a circular cylinder in a uniform #ow at medium Reynolds numbers. It uses rotary cylinder
oscillations controlled by the feedback signal of a reference velocity in the cylinder wake. The
e!ectiveness of this feedback control is evaluated by measuring the response of mean and
#uctuating velocities in the cylinder wake, the spanwise correlation, the power spectrum, and
the #uid forces acting on the cylinder. It is found that the velocity #uctuations and the
#uid forces are both reduced by the feedback control with optimum values of the phase lag and
feedback gain. The simultaneous #ow visualization synchronized with the cylinder oscillation
indicates the attenuation as well as the mechanisms of vortex shedding under the feedback
control, which is due to the dynamic e!ect of cylinder oscillation on the vortex formation
 
I have done a search and found some papers on active techniques. But what I am looking for is if there are any few standard and common active techniques that people use to control vortex shedding.

For example, when we mention flow speed measurement, the most common methods are using pitot-static tubes and hot wires etc.

So are there any common active techniques to control vortex shedding?
 

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