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-   -   how can the vortex develop? (http://www.cfd-online.com/Forums/main/5915-how-can-vortex-develop.html)

Peter March 30, 2003 22:17

how can the vortex develop?
 
Hi everyone,

Could anybody explain to me how can the vortex actually developed on the surface of the body? Is that because of the curvature or some other reasons? Any comments are very welcomed.

Thanks, peter

Jonas Larsson March 31, 2003 03:43

Re: how can the vortex develop?
 
It sounds as if you are confusing "vortex" and "voticity". Vorticity develops in the boundary layers on all surfaces as a result of the viscous forces working in the boundary layer.

I might be answering the wrong thing here - I think that you might need to clarify your question a bit more.

Peter March 31, 2003 09:18

Re: how can the vortex develop?
 
Thanks a lot. I don't actually understand the difference between vortex & vorticity....Can you please explain in a bit details?

If possible, please kindly tell me when these things will happen. I come across the word vortex for a few times but still not sure how it actually work. Thanks for your time.

Jonas Larsson March 31, 2003 09:28

Re: how can the vortex develop?
 
A vortex is a localised physical flow structure with a certain size, strength etc - it is what you can see when your bath-tub drains, behind the wing-tips of aircrafts, behind rowing oars (sp?) when you row a boat etc.

Vorticity is a mathematical property of the velocity field (del x vel_vector). Often vorticity can give rise to a localised vortex - for example when a boundary layers (which has vorticity) hits a surface mounted object the vorticity in the boundary layer will create a localised horse-shoe vortex in front of the object.

I suggest that you check out a basic book on fluid dynamics for more info, for example Incompressible Flow by Panton, Physcial Fluid Dynamics by Trition or Basic Fluid Dynamics by Wilcox. Those will explain the concepts of vorticity and vortices much better than we can ever do here.


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