Defect Dynamics for Spiral Chaos in Rayleigh-Bénard Convection

A theory of the novel spiral chaos state recently observed in Rayleigh-Bénard convection is proposed in terms of the importance of invasive defects, i.e., defects that through their intrinsic dynamics expand to take over the system. The motion of well developed spiral defects is dominated by wave vector frustration, rather than a rotational motion driven by a vertical vorticity field. This leads to a continuum of spiral frequencies, and a spiral may rotate in either sense depending on the wave vector of its local environment. Results of extensive numerical work on equations modeling the convection system provide confirmation of these ideas.