Circadian clock
This model is based on the paper “Chaos and birhythmicity in a model of circadian oscillations of the PER and TIM proteins in Drosophila” by Leloup and Goldbeter which has been made into a spatial reaction diffusion model. It defines over 30 reactions between 10 species in a single compartment without membrane effects. Due to the complexity of the mathematical description, it is not given in full here.
Example Snapshot

The last timestep of the circadian clock model in a 2D domain.