In combustion engineering and explosion studies, the Markstein number (named after George H. Markstein who first proposed the notion in 1951[1]) characterizes the effect of local heat release of a propagating flame on variations in the surface topology along the flame and the associated local flame front curvature.
The larger the Markstein length, the greater the effect of curvature on localised burning velocity.
George H. Markstein (1911—2011) showed that thermal diffusion stabilized the curved flame front and proposed a relation between the critical wavelength for stability of the flame front, called the Markstein length, and the thermal thickness of the flame.
[4] Phenomenological Markstein numbers with respect to the combustion products are obtained by means of the comparison between the measurements of the flame radii as a function of time and the results of the analytical integration of the linear relation between the flame speed and either flame stretch rate or flame curvature.
[8] The Markstein number with respect to the unburnt gas mixture was derived by Paul Clavin and Forman A. Williams in 1982, using activation energy asymptotics.
[9][10] The formula was extended to include temperature dependences on the thermal conductivities by Paul Clavin and Pedro Luis Garcia Ybarra in 1983.
, in which case, we have In the constant transport coefficient assumption,