SURFACE-DENSITY FUNCTION IN PREMIXED TURBULENT COMBUSTION MODELING, SIMILARITIES BETWEEN PROBABILITY DENSITY-FUNCTION AND FLAME SURFACE APPROACHES

To characterize the dynamics and the physical properties of isoconcent ration surfaces of a random reactive scalar field, an instantaneous is osurface quantity and its transport equation are introduced. For turbu lent flows, the mean area of isoconcentration surface per unit volume is studied through its transport equation derived by using the probabi lity density function (pdf) formalism. This approach allows the value of the reactive scalar used to define the level surface to be treated as an independent variable. It also leads to the definition of a surfa ce density function. The developed formalism is applied to premixed tu rbulent combustion and a bridge is built between modeling approaches b ased on pdf, and others based on the flame surface concept. (C) 1995 A merican Institute of Physics.