Computational Studies of Turbulent Flows with Chemical Reaction

Abstract

Research about turbulent mixing of non-reactive flows has progressed recently, particularly in the field of the computational modeling of turbulence. The first practical purpose of these studies is to acquire a more precise knowledge of the fluxes of turbulent transport of momentum, mass and enthalpy, which are determining factors for the time-mean velocity, mass fraction, temperature.

When the turbulent mixing of chemically reactive flows are considered, the time-mean characteristics are determined also by the reaction rates, and, as the molecular fluxes are not the only data to be taken into account, the molecular reaction rates must be modified by the fluctuations themselves, especially the temperature and the concentration fluctuations.

The analytical basis for an approach of this problem, which is clearly in the line of the methods already proposed for non-reactive flows, is presented. The effects that the fluctuations and their correlations can have on the mean reaction rate are discussed and, alternatively, the influence the chemical reactions can have on the fluctuations. Some numerical calculations are presented and discussed, and particular difficulties and limitations of the method, due to the occurrence of chemical reactions, will be shown.