A HYBRID ONE-POINT AND 2-POINT APPROACH FOR ISOTHERMAL REACTING FLOWSIN HOMOGENEOUS TURBULENCE

A procedure that combines a one-point probability density function (pd f) and two-point correlation functions (TPCF's) is introduced to simul ate the multispecies chemical reactions carried by a homogeneous turbu lence field. In this procedure, the pdf equation and the evolution of TPCF's are treated in parallel using time splitting. The one-point pdf equation requires closure of only the molecular diffusion terms. At a ny instant the time scale for the linear mean square estimate closure is obtained from the parallel solutions of the equations for TPCF's, u sing a physical-space EDQNM (eddy damped quasinormal Markovian) closur e for the advection terms and a similarity assumption for the reaction terms. With this procedure, a study of chemical reactions with four o r five species is possible. The model's predictions are in good agreem ent with DNS data and a fully two-point pdf description of simpler kin etic schemes. Results for a range of Damkohler numbers, Schmidt number s, and Reynolds numbers that are beyond the reach of DNS are also show n.