A CLOSURE-MODEL FOR HOMOGENEOUS CHEMICAL-REACTIONS

A closure procedure based on the probability density functions of the concentrations of chemically inert species has been developed and appl ied to derive the mathematical forms of the average values of the nonl inear reaction terms in the turbulent mass balances of reacting specie s. Single and complex (competitive-consecutive and parallel), instanta neous and fast homogeneous chemical reactions have been considered whe n initially separated reagents mix. The probability density functions of the inert type composition variables formed with reagent concentrat ions have been approximated with the Beta PDF; the distribution of con centration variance being measured or calculated from the turbulent mi xer model previously proposed by the author. Some features of the simp le, first order closures for single and complex chemical reactions hav e been interpreted and explained with the use of the present model. An extensive comparison of the model predictions with experimental resul ts has been performed as well.