The interactions between parametrically forced waves, excited by 2
commensurate frequencie on the surface of a fluid, yield a host of
different superlattice-type patterns. These states are generated via a
number of different 3--wave resonant interactions. They occur either
as symmetry--breaking bifurcations of hexagonal patterns composed of a
single unstable mode or via nonlinear interactions between the two
primary unstable modes generated by the two forcing frequencies. Near
the system's bicritical point, we find that competing nonlinear states
yield a highly disordered regime in both space and time.
Experimentally, we rapidly stabilize this regime to a variety of
nonlinear states via open-loop control by perturbation with a third
excitation frequency, whose temporal symmetry governs the temporal and
spatial symmetry of the selected nonlinear state. This technique also
excites rapid switching between different nonlinear states.
Audio requires RealPlayer by RealNetworks.
To begin viewing slides, click on the first slide below. (Or, view as pdf.)
Author entry (protected)