1,287 research outputs found
Resonantly Forced Inhomogeneous Reaction-Diffusion Systems
The dynamics of spatiotemporal patterns in oscillatory reaction-diffusion
systems subject to periodic forcing with a spatially random forcing amplitude
field are investigated. Quenched disorder is studied using the resonantly
forced complex Ginzburg-Landau equation in the 3:1 resonance regime. Front
roughening and spontaneous nucleation of target patterns are observed and
characterized. Time dependent spatially varying forcing fields are studied in
the 3:1 forced FitzHugh-Nagumo system. The periodic variation of the spatially
random forcing amplitude breaks the symmetry among the three quasi-homogeneous
states of the system, making the three types of fronts separating phases
inequivalent. The resulting inequality in the front velocities leads to the
formation of ``compound fronts'' with velocities lying between those of the
individual component fronts, and ``pulses'' which are analogous structures
arising from the combination of three fronts. Spiral wave dynamics is studied
in systems with compound fronts.Comment: 14 pages, 19 figures, to be published in CHAOS. This replacement has
some minor changes in layout for purposes of neatnes
Three-Dimensional Autonomous Pacemaker in the Photosensitive Belousov-Zhabotinsky medium
In experiments with the photosensitive Belousov-Zhabotinsky reaction (PBZR)
we found a stable three-dimensional organizing center that periodically emits
trigger waves of chemical concentration. The experiments are performed in a
parameter regime with negative line tension using an open gel reactor to
maintain stationary non-equilibrium conditions. The observed periodic wave
source is formed by a scroll ring stabilized due to its interaction with a
no-flux boundary. Sufficiently far from the boundary, the scroll ring expands
and undergoes the negative line tension instability before it finally develops
into scroll wave turbulence. Our experimental results are reproduced by
numerical integration of the modified Oregonator model for the PBZR. Stationary
and breathing self-organized pacemakers have been found in these numerical
simulations. In the latter case, both the radius of the scroll ring and the
distance of its filament plane to the no-flux boundary after some transient
undergo undamped stable limit cycle oscillations. So far, in contrary to their
stationary counterpart, the numerically predicted breathing autonomous
pacemaker has not been observed in the chemical experiment
Spiral flames
AbstractWe describe computations of periodic and meandering spiral patterns in a reaction-diffusion model of flames
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