Re: [Phys-L] endless vortex lines

[brian whatcott <betwys1@sbcglobal.net>]

On 12/6/2014 7:09 PM, John Denker wrote:
> On 12/06/2014 02:10 PM, Chuck Britton wrote:
> > Does this Mathematical Result apply to tornadoes, hurricanes, bathtub
> > drains, coffee cups etc.?
> Yes.
...or No - depending on which source you address.
For example:
http://farside.ph.utexas.edu/teaching/336L/Fluidhtml/node57.html
offers this:
"This result is essentially an equation of continuity for vortex 
filaments. It implies that the product of the magnitude of the vorticity 
and the cross-sectional area, which is termed the/vortex intensity/, is 
constant along the filament. It follows that a vortex filament cannot 
terminate in the interior of the fluid. For, if it did, the 
cross-sectional area,$S$, would have to vanish, and, therefore, the 
vorticity,$\omega$, would have to become infinite. Thus, a vortex 
filament must either form a closed vortex ring, or must terminate at the 
fluid boundary."

However, here's a cautionary note, which goes to excuse some 
too-confident assertions in the matter of vortex lines:
https://www.eng.fsu.edu/~dommelen/research/lines.html

Brian Whatcott     Altus OK