Zeldovich spontaneous wave

A Zeldovich spontaneous wave, also known as the Zeldovich gradient mechanism, is a theoretical type of reaction wave that can occur in a reacting substance, such as a gas mixture, where the initial temperature varies across different locations. This variation in temperature creates gradients that cause different parts of the substance to react at slightly different times, driving the wave's propagation.

Source: Wikipedia — Zeldovich spontaneous wave (CC BY-SA 4.0)