The wrinkling of a flame due to viscosity

The authors present a numerical study of flame wrinkling due to viscosity. They model a flame propagating in a swirling, viscous, premixed combustible fuel inside a closed, rectangular vessel, and analyze the influence of vorticity produced by the no-slip condition along solid walls on the motion of the flame. They show that viscosity wrinkles the flame front, increasing the surface area available for burning and thus accelerating the combustion process. They perform experiments over a range of nondimensional burning velocities, and show that the slower the flame speed, the greater the effect of viscosity on the rate of combustion, when compared to an inviscid calculation with the same flame speed.