Session MM - Chaos and Fractals.
MIXED session, Tuesday afternoon, November 23
Whidbey, Westin Seattle
We present results of experimental studies of the propagation of chemical fronts in a chain of oscillating vortices, a system in which mixing of passive impurities is chaotic. A variation of the photosensitive Belousov-Zhabotinsky chemical reaction is used in which a reaction pulse can be triggered with a silver wire. The speed at which this pulse propagates through the vortex chain is measured and compared with recent theories(M. Cencini, A. Torcini, D. Vergni and A. Vulpiani, Phys. Fluids 15, 679 (2003)) for front propagation in a similar flow. Several mode-locked regimes are observed in which the pulse propagates an integer number of vortex widths in an integer number of oscillation periods. Measurements of the widths of these locking regimes are made as a function of the oscillation amplitude, revealing classic Arnol’d tongue behavior.