I wrote a small program to simulate refraction in reaction-diffusion systems. Below are movies of the results of the simulations.

1. Shorter wavelength
2. Longer wavelength
3. Longer period, shorter wavelength
4. Shorter period, same wavelength
5. Cicular wave. Longer wavelength
6. Circular wave. Shorter wavelength
7. Stripes. Shorter wavelength
8. Stripes. Longer wavelength