The Oregonator (Field & Noyes 1974) captures BZ reaction oscillations in three variables: HBrO₂ (x), Br⁻ (y), and Ce⁴⁺ (z). The equations are:
ε·ẋ = x(1−x) − (f·y·(x−q))/(q+x)
ε'·ẏ = −y + f·z
ż = x − z
For certain parameter ranges, the system shows deterministic chaos. The 3D phase portrait (left) reveals a strange attractor; the Poincaré section (right, plane z=const) exposes the fractal structure. Positive Lyapunov exponent confirms chaos. The Rössler attractor has topologically similar "folded band" structure.