A statistical description of turbulent diffusion flame holes

A statistical approach to the dynamics of diffusion-flame holes is presented. The dynamics of the holes are assumed to be controlled by the edge-flame velocity that is determined by the mixture fraction rate of dissipation, a random variable in a turbulent flow. The formulation is then specialized to the case of small circular holes and a stochastic model is used to investigate the dynamics of the joint probability density function of flame-hole radius and scalar dissipation. The associated Fokker-Planck transport equation for the joint pdf is solved and the hole area evolution with time is computed. Furthermore, the one-dimensional marginal probability density function transport equation for the hole radius is derived and the conditional edge-flame velocity is studied for both expanding and collapsing holes.