Scaling and dynamics of "flow distributed oscillation patterns" in the Belousov-Zhabotinsky reaction

The formation of "flow distributed oscillation" (FDO) patterns in the Belousov-Zhabotinsky (BZ) reaction is studied experimentally. We confirm the dependence of the pattern wavelength on the flow velocity and the concentration of the reactant species BrO3- and H+ us predicted in a previous study. We also report on the initial development of the FDO patterns. In contrast to simple interpretations, the patterns arise through a "wave splitting" mechanism in which a pair of counter-propagating wave pulses are created from a pacemaker site at some distance ahead of the pattern: one of these waves propagates with the flow and leaves the reactor, the other propagates against the flow and eventually settles to form the next band of the FDO pattern. This initiation mechanism is confirmed in numerical studies based on the Oregonator model. These computations also indicate the possibility of complex dynamics similar to the "resonance patterns" reported in studies of the propagation of BZ waves through capillary tubes.