Stability of laminar premixed planar flame with tangential velocity discontinuity

The laminar premixed planar flame having a discontinuity of tangential velocity across the planar flame front is examined asymptotically as a first approximation of the flame propagating in a rotational flow field. The premixed flame generates vortical motions that convect downstream and make the velocity tangential to the flame front different between both sides of the front. The clarification of this effect upon the stability of premixed flame is the objective of this study. The flame structure is described by the large activation energy asymptotics and the long wave approximation. Since any assumption on the thermal expansion is not used, the coupling mechanisms between the hydrodynamics and the diffusion processes are described. Viscous effects are included and near-unity Lewis number is assumed. The results show that the presence of tangential velocity discontinuity makes the flame more unstable and the characteristic wavelength of flame wrinkles larger. It was reported that if the planar flame propagates normally in a uniform flow, the viscosity has a minor effect on the flame dynamics compared with other diffusion processes([1, 2]). However, this analysis shows that the tangential velocity discontinuity makes the viscosity effect larger and non-negligible.