flame A flame (from Latin '' flamma'') is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction taking place in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density they ...

may exhibit intrinsic instabilities of several kinds when one or more of the physico-chemical balances associated with its propagation is offset. In

premixed flame A premixed flame is a flame formed under certain conditions during the combustion of a premixed charge (also called pre-mixture) of fuel and oxidiser. Since the fuel and oxidiser—the key chemical reactants of combustion—are available througho ...

s, the primary instability is a hydrodynamic instability — known as the Darrieus-Landau instability — which results from thermal expansion across the flame interface. In non-premixed (diffusion) flames, thermo-diffusive instabilities are predominant while the hydrodynamic instability plays a secondary role.

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{{chemistry-stub Combustion