Can someone please explain to me the concept of vortex breakdown?

In summary, vortex breakdown is a phenomenon that occurs when a swirling fluid, such as air or water, reaches a critical point and starts to break down into smaller vortices. This process is often observed in natural and man-made systems, such as tornadoes and jet engines, and can have significant impacts on the flow dynamics and stability. Vortex breakdown is a complex concept that is still being studied and understood by scientists and engineers.
  • #1
sashankhrao
19
0
Can someone please explain to me the concept of vortex breakdown?
 
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  • #2


Other than viscosity? Is there a particular instability you are thinking about?
 
  • #3


Hi Andy,

Thanks for your reply.Actually I don't understand the concept of vortex breakdown and its relation to Swirl Number (SN) which is defined as the ratio of swirl to meridianol motion strengths. I have read that vortex breakdown diappearance occurs as the SN decreases.
 
  • #4
Yikes... I've never heard of a swirl number. My only resource is "Vortex Dynamics" by Saffman.

I found a link here (http://www.enme.umd.edu/combustion/underwater_propulsion.htm) with some information that helped.

If I understand your context, you are referring to a "vortex with helicity", which I think means that the vortex lines form axial screw patterns. The swirl number seems to be related to the pitch angle of the vortex lines, but I can't tell for sure. A vortex with helicity has moving vortex lines, which are then subject to instabilities.

"Vortex breakdown" is a rapid change in the core radius of the vortex filament or tube- it was an experimentally-discovered phenomenon, and is characterized by a rapid increase in the core radius, which appears as a bubble or spiraling thread. Saffman claims there is no widely accepted theory for this phenomenon yet.

In practical terms, it means that the relationship between the two is established empirically- by varying the swirl number (and other relevant parameters, for example capillary number, Reynolds number, Rossby number...)- this is glaringly missing from the above webpage. There's probably a lot of opportunity for original contributions to the topic.
 
  • #5


Hi Andy,

Thank you for your interest in my doubt. If you could assist me with your email address i could send you the document that i am trying to understand. Its on Vortex Breakdown. A pdf file.
 
  • #6


Sashankhrao,

I just sent you a personal message with my address. Hope I can help!
 

1. What is vortex breakdown?

Vortex breakdown is a phenomenon that occurs when a swirling flow of fluid reaches a certain critical point and begins to collapse inward on itself. This results in a sudden decrease in swirling motion and the formation of a stable central core within the vortex.

2. How does vortex breakdown occur?

Vortex breakdown occurs due to a combination of factors, including the strength and direction of the swirling flow, the shape and size of the container or channel in which the flow occurs, and the properties of the fluid itself. When these factors align in a certain way, the swirling flow reaches a critical point and vortex breakdown occurs.

3. What are the applications of vortex breakdown?

Vortex breakdown has important applications in a variety of fields, including aerodynamics, fluid mechanics, and combustion. It is also of interest in meteorology, as it can play a role in the formation of tornadoes and other types of severe weather.

4. How is vortex breakdown studied?

Vortex breakdown is studied using a combination of experimental and computational techniques. These may include laboratory experiments using models and fluids that mimic natural conditions, as well as computer simulations and mathematical modeling.

5. What are the potential implications of vortex breakdown?

Understanding vortex breakdown can have important implications for a wide range of fields, from improving aircraft and vehicle design to predicting and mitigating the effects of severe weather events. It can also lead to a deeper understanding of fundamental principles in fluid dynamics and other related areas of study.

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