Oregonator model on a 2D reaction-diffusion grid simulates the Belousov–Zhabotinsky chemical oscillator. Spiral waves and target patterns emerge from local activator-inhibitor kinetics coupled by diffusion.
Oregonator (Field-Noyes 1974): ∂u/∂t = (1/ε)(u−u²−f·v·(u−q)/(u+q)) + Du·∇²u, ∂v/∂t = u−v. Variable u = activator (HBrO₂), v = inhibitor (ferriin). Spiral waves are topological defects; target patterns arise from pacemaker cells. Winfree 1972 first observed these in the BZ reaction.