Complexity in spiral wave dynamics^a)

In closed systems of the Belousov–Zhabotinsky reaction a large number of dynamic states found in open systems is sampled as they evolve in time. During such slow aging processes of thin solution layers, prepared under appropriately chosen chemical conditions, an unexpectedly rich variety of spiral tip behavior was observed experimentally. Within a (concentration, time) parameter plane, the movement of free ends of waves was classified as follows: (a) in a stable domain–periodic rigid rotation with cores of small (200 μm) or very large (2 mm) diameter; quasiperiodic compound motion along a hypocycle, a straight loopy line or an epicycle; complex meandering composed of possibly more than two components; (b) rectilinear tip motion indicating the boundary of spiral wave stability; and (c) in an unstable domain—shrinking of open ends of wave fronts during propagation. The main properties of these parameters are compared with recently published computer calculations.