CHEMICAL WAVE RESPONSES TO PERIODIC STIMULI IN VULNERABLE EXCITABLE MEDIA

A reaction-diffusion model of the Belousov-Zhabotinsky (BZ) reaction i s studied in which an initial 'conditioning' wave (CW) propagates thro ugh an excitable system and sets up a region of inhomogeneity in which the system becomes spontaneously oscillatory. The subsequent oscillat ions in the concentrations of the intermediate species within this reg ion can act as potential initiation sources for subsequent wave struct ures. The range of different responses is determined for a 1D configur ation by numerical computation and the parameter combinations for the different types are located. Depending on the length of this region an d the frequency of the spontaneous oscillations, the system may develo p: sustained counter-propagating wave pairs, waves that propagate only in the opposite direction to the CW, waves that propagate only in the same direction as the CW, waves that propagate in alternating directi ons or no subsequent wave development despite the periodic initiation. The relationship of these different responses to experimental reactio n-diffusion structures reported recently is discussed and the role of the inhibitory species and its spatial profile is revealed.