FORMATION PROCESS OF SPIRAL PATTERNS IN AN OSCILLATORY MEDIA

Spiral pattern is a typical pattern observed in dissipative systems. It is well known' that there are two types of spiral patterns, one is formed in excitable media and the other in oscillatory media. In excitable media, spiral patterns are obtained by somewhat artificial way. On the other hand, spiral patterns in oscillatory media seem to be born spontaneously from random initial state. We concentrate on the nucleation process and the growth process of spiral patterns in oscillatory media using a simple reaction diffusion model which includes the Bonhoeffer-van der Pol type dynamics. au at (1) The condition for the formation of spiral pattern is shown by the 2D and 1D simulations of the model (Figure 1). At the same time, we obtain the condition determining the orientation of spiral pattern. beta- 0.0 beta--0.