Instabilities and Chaos in Falling Objects (Nature, July 1997)

Experimental discovery and theoretical analysis of a new type of intermittency and chaos in falling disks.

S. Field, M. Klaus, M. Moore, and Franco Nori,
Nature 387, 252 (July 17, 1997)

Featured in: Science News 152, 37 (July 19, 1997);
Science On-Line: ScienceNow (July 17, 1997);
Physics News of the American Institute of Physics, Number 331 (July 24, 1997),
Science News 154, 285-287 (October 31, 1998). Three-page featured article and the Coverstory.
Also, in several newspapers and TV.

We investigate experimentally and theoretically the behavior of falling disks in a fluid and identify several dynamical regimes as a function of the moment of inertia and Reynolds number: steady falling, periodic oscillating, chaotic, and continuous tumbling. One-dimensional iteration maps of the disk angles at turning points were constructed to explore the evolution of the dynamics, as boundaries between these regimes are crossed. We obtain the first experimental evidence of a progression from fixed-point to chaotic motion via a novel type of intermittency, characterized by a discontinuity in the iteration map.

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