Belousov–Zhabotinsky ●

A two-variable Oregonator reaction-diffusion model of the BZ reaction as an excitable chemical medium. u is the fast activator (~HBrO₂), v the slow recovery variable (~oxidized catalyst). Spiral and target waves emerge just like in a real BZ petri dish. Drag on the dish to inject excitation and nucleate new waves.

∂u/∂t = Du∇²u + (1/ε)[ u(1−u) − f·v·(u−q)/(u+q) ]

∂v/∂t = Dv∇²v + (u − v)

Two-variable Oregonator. Integrated with forward Euler in time and a 5-point Laplacian in space, sub-stepped per frame, with u,v clamped to [0,1] for stability.