# Active techniques to control vortex shedding

• ghost85
In summary: Yes, there are several common techniques used to control vortex shedding, such as using velocity measurements, using static or moving obstacles, and using rotary or spinning devices.
ghost85
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.

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?

## 1. What is vortex shedding and why does it occur?

Vortex shedding is a phenomenon that occurs when a fluid flows past a bluff body, such as a cylinder or a bridge. It results in the formation of alternating vortices on either side of the body, which can cause undesirable vibrations and drag forces. This occurs due to the interaction between the fluid flow and the body's geometry, creating areas of low pressure behind the body that induce the formation of vortices.

## 2. What are some common active techniques used to control vortex shedding?

Some common active techniques used to control vortex shedding include modifying the body's geometry, using flow control devices such as vortex generators or spoilers, and applying oscillatory control techniques such as active flow control or synthetic jet actuators. These techniques aim to disrupt the formation of vortices and reduce their strength, thereby mitigating the negative effects of vortex shedding.

## 3. How effective are active techniques in controlling vortex shedding?

The effectiveness of active techniques in controlling vortex shedding depends on various factors such as the body's geometry, flow conditions, and the specific technique used. In some cases, active techniques can completely eliminate vortex shedding, while in others, they may only reduce its intensity. It is essential to carefully consider these factors and conduct experiments or simulations to determine the most effective technique for a specific application.

## 4. Can active techniques be applied to any type of bluff body?

Active techniques can be applied to various types of bluff bodies, including cylinders, spheres, and airfoils. However, the effectiveness of these techniques may vary depending on the body's shape, size, and flow conditions. It is important to assess the specific characteristics of the body and the flow before deciding on the most suitable active technique for controlling vortex shedding.

## 5. Are there any drawbacks to using active techniques to control vortex shedding?

While active techniques can effectively reduce or eliminate vortex shedding, they may also have some drawbacks. These may include increased complexity, higher costs, and potential maintenance issues. Additionally, some techniques may also introduce additional noise or vibrations, which could affect the overall performance of the system. It is crucial to carefully consider these factors and weigh them against the benefits before implementing active techniques for controlling vortex shedding.

• Mechanical Engineering
Replies
1
Views
3K
• Mechanical Engineering
Replies
11
Views
3K
• Mechanical Engineering
Replies
10
Views
4K
• Mechanical Engineering
Replies
1
Views
1K
• Chemistry
Replies
2
Views
987
• Mechanical Engineering
Replies
2
Views
1K
• Mechanical Engineering
Replies
4
Views
3K
• Mechanical Engineering
Replies
5
Views
1K
• Mechanical Engineering
Replies
5
Views
1K
• Electromagnetism
Replies
1
Views
10K