Some aspects of the freely propagating premixed flame in a spatially periodic flow field

The premixed flame situated in a spatially periodic flow field is examined using the passive propagation model with the local flame speed affected by stretch and nonequidiffusion. Numerical solution shows that the average flame speed increases with either increasing fluctuation amplitude or increasing wavelength of the imposed flow field, and that the flame surface can locally extinguish for sufficiently large fluctuation amplitude of the imposed flow. Perturbation solutions in the weakly wrinkled flame and the thin flame limits are presented. The formation of corners on the flame surface in the thin flame limit is illustrated, and the structure of the corner is further found to resemble that of the Bunsen flame. The premixed flame situated in a two-dimensional periodic flow field is also analyzed in the Huygens limit, leading to the observation that flame surface discontinuities exist in the form of cones.