Detonation

A detonation is a self-sustaining Shock wave coupled to a chemical reaction front, in which the shock compresses the reactive material to ignition temperature, and the energy released by the reaction sustains the shock. Unlike a deflagration, which propagates at subsonic speed through thermal conduction and diffusion, a detonation moves at supersonic speed — typically thousands of meters per second — and the reaction zone is compressed into a thin layer immediately behind the shock. The Chapman-Jouguet condition identifies the detonation speed as the minimum speed at which the reaction products can expand away from the shock while still satisfying conservation laws; slower speeds would produce unsupported shocks that decay, while faster speeds require external energy input. This self-organizing structure — a shock that creates the conditions for its own propagation — is one of the most striking examples of a coupled nonlinear system producing a stable, traveling coherent structure from the interplay of fluid mechanics and chemical kinetics.