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SUMMARY:Particle–Wave Association on a Fluid Interface - Alex Silver ( T
 CM)
DTSTART:20081024T150000Z
DTEND:20081024T153000Z
UID:TALK14685@talks.cam.ac.uk
CONTACT:Daniel Cole
DESCRIPTION:S. Protiére\, A. Boudaoud and Y. Couder\n"Journal of Fluid Me
 chanics 554\, 85 (2006)":http://dx.doi.org/10.1017/S0022112006009190\n\nA 
 small liquid drop can be kept bouncing on the surface of a bath of the sam
 e fluid for an unlimited time when this substrate oscillates vertically. W
 ith fluids of low viscosity the repeated collisions generate a surface wav
 e at the bouncing frequency. The various dynamical regimes of the associat
 ion of the drop with its wave are investigated first. The drop\, usually a
  simple ‘bouncer’\, undergoes a drift bifurcation when the forcing amp
 litude is increased. It thus becomes a ‘walker’ propagating at a const
 ant velocity on the interface. This transition occurs just below the Farad
 ay instability threshold\, when the drop becomes a local emitter of a para
 metrically forced wave. A model of the particle–wave interaction account
 s for this drift bifurcation. The self-organization of several identical b
 ouncers is also investigated. At low forcing\, bouncers form bound states 
 or crystal-like aggregates. At larger forcing\, the collisions between wal
 kers reveal that their interaction can be either repulsive or attractive\,
  depending on their distance apart. The attraction leads to the spontaneou
 s formation of orbiting pairs\, the possible orbit diameters forming a dis
 crete set. A theoretical model of the non-local interaction resulting from
  the interference of the waves is given. The nature of the interaction is 
 thus clarified and the various types of self-organization recovered.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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