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-   -   vortex, vorticity, swirl, helicity (http://www.cfd-online.com/Forums/main/4282-vortex-vorticity-swirl-helicity.html)

lhb January 12, 2002 06:54

vortex, vorticity, swirl, helicity
 
What's the difference between vortex, vorticity, swirl and helicity? I want use plot3d function swirl to analyse the flow field, who can tell me it's meaning?

Paul January 13, 2002 02:21

Re: vortex, vorticity, swirl, helicity
 
Vortex itself is a description of a special flow phenomenon. In fluid mechanics, it is strictly defined by vorticity. The helicity was originally defined as the intergation of scalar product of velocity vector and the vorticity vector. The momentum, the energy and the helicity are there main conservation variables of fluids. These things can be found in Frisch's `Turbulence'. I never come to strict definiation of swirl. It sounds like the vortex. Anyone knows?


Chuck January 13, 2002 13:32

Re: vortex, vorticity, swirl, helicity
 
Swirl and Helicity are the same thing: a scalar property field defined as vorticity-dot-velocity. It defines the component of vorticity which is parallel to the local velocity vector.


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