FYFD

Tag: period doubling

  • The Fluid Dynamical Sewing Machine

    The Fluid Dynamical Sewing Machine

    Anyone who has poured a viscous fluid like honey or syrup will have noticed its tendency to coil like rope. A similar effect is observed when a viscous fluid stream falls onto a moving belt. The photos above show some of the patterns seen in these “fluid-mechanical sewing machines” depending on the height of the thread and the speed of the moving belt. Notice how some of the patterns are doubles of another (i.e. two coils per side instead of one). This period doubling behavior is often seen in systems on their way to chaos.  (Photo credits: S. Chiu-Webster and J. Lister)

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    The Chaos of a Bouncing Droplet

    This video explores chaos in a bouncing droplet.  A drop of silicon oil bounces on a vibrating bath of oil; the thin layer of air injected with each bounce between the droplet and bath keeps them from coalescing. Initially, the droplet behaves like a bouncing ball, jumping once per oscillation. As the vibration amplitude increases, the droplet begins making a small jump, then a large jump, then a small jump, and so on. This is called period doubling since the droplet now jumps in a pattern with twice the period of the original and is a hallmark of nonlinear dynamical systems. Further increase in the vibration amplitude leads to chaotic bouncing and occasional ejecta. (Video credit: D. Terwagne et al.)