Spiral wave dynamics

We analyse time series of meandering spiral waves in a two-dimensional model of excitable tissue. Time series of the spiral tip studied are quasiperiodic and erratic. In the case of erratic motion an intrinsic non-stationarity of the tip position is present due to the possibility of arbitrary large excursions. The correlation dimension D2 and correlation entropy K2 are then not well defined. However, low-dimensional behaviour is found in the spiral tip velocity for the erratic series. Non-stationarity of the tip position can be explained from chaotic behaviour of the tip velocity.