Bi-Stable Spiral Waves: Stepped Spiral Waves

Spiral Waves in Nonlocal Equations

We present a numerical study of rotating spiral waves in a partial integro-differential equation defined on a circular domain. This type of equation has been previously studied as a model for large scale pattern formation in the cortex and involves spatially nonlocal interactions through a convolution. The main results involve numerical continuation of spiral waves that are stationary in a rota...

When does cyclic dominance lead to stable spiral waves?

Species diversity in ecosystems is often accompanied by the self-organisation of the population into fascinating spatio-temporal patterns. Here, we consider a two-dimensional threespecies population model and study the spiralling patterns arising from the combined effects of generic cyclic dominance, mutation, pair-exchange and hopping of the individuals. The dynamics is characterised by nonlin...

Spiral waves in accretion discs

In the first part of this article, we review the observational evidence for spirals in the accretion discs of cataclysmic variables. It is shown that with the increasing amount of data available, spirals appear to be an omnipresent feature of accretion discs in outburst. Spirals seem to live until decline that is, for several tens of orbital periods. We then study the formation of spiral shocks...

Analytical approximations for spiral waves.

We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R(0). For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only...

Alfven Waves in Spiral Interplanetary Field