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Question on ring vortex

  1. Sep 4, 2008 #1
    my question relates to the axisymmetrical ring vortex.
    i know that vorticity must remain constant within a tube, (helmholtz vortex theorem 2)
    so does that mean that the vortex lines on the outside of the ring are longer (spinning faster)
    than the ones on the inside?

    also is that what makes vortex rings propagate?
    like, does the ring draw energy from its translational speed and put it into maintaining its vorticity, or is it the other way around?
    or am i completely off?
  2. jcsd
  3. Nov 13, 2008 #2
    skywolf, the particles must all move at the same speed as the speed is determined by the pressure. So particles close to the centre or periphery are at the same speed and so have different RPM. That means they shear which helps the vortex to decay. The ring vortex swims by entrainment in front and ejection aft, almost propulsion by negative drag. There are two kinds of vorticity, convection as in a smokers ring and diffusion as in airfoil lift. See my PDF through the website www.newfluidtechnology.com[/URL] called "lift and the Coanda Effect"
    Last edited by a moderator: Apr 23, 2017
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