Darrieus–Landau instability

Summary

The Darrieus–Landau instability is the hydrodynamic instability of a premixed flame front. It comes from the expansion of gas across the flame. Burnt gas is lighter than fresh gas, and the flow deflected by a wrinkled front makes the wrinkles grow. In the model of a flame as a thin front, every wrinkle grows, at a rate proportional to its wavenumber. It was found independently by Georges Darrieus and Lev Landau, and it explains why large flames are usually wrinkled or cellular.