Characteristic chemical time scales identification in reactive flows

Turbulent combustion models that are used in Reynolds Averaged Numerical Simulations (RANS) and in Large-Eddy Simulations (LES) are deeply influenced by the relative time scales between turbulent and chemical phenomena. In order to evaluate these interactions in detailed chemistry configurations, a strategy to compute and classify the chemical time scales is needed. A method called Chemical Time Scales Identification (CTS-ID) is presented, on the basis of the Jacobian analysis of the chemical source term. All time scales obtained through this analysis are associated with directions in the composition space. By comparing these directions with the physical trajectory, the time scales are ordered according to their contribution. The chemical path associated to each of these time scales is also obtained from this analysis. The CTSID method is applied on two test cases that present both fast and slow time scales.