On relation of the Conditional Moment Closure and unsteady Flamelets

We consider the relation of the Conditional Moment Closure (CMC) and the unsteady Flamelet Model (FM). The CMC equations were originally constructed as global equations while FM was asymptotically derived for a thin reaction zone. The recent tendency is to use FM-type equations as global equations. We investigate the possible consequences and suggest a new version of FM – Coordinate-Invariant FM (CIFM). Unlike FM, CIFM complies with conditional properties of the exact transport equations which are effectively used in CMC. We analyse the assumptions needed to obtain another global version of FM – Representative Interactive Flamelets (RIF) – from original FM and demonstrate that, in homogeneous turbulence, one of these assumptions is equivalent to the main CMC hypothesis. †Dept. of Mechanical Engineering, the University of Queensland, Qld 4072, Australia