G-scheme-based simplification and analysis methodology for hydrocarbon ignition

For the simulation of reactive flows, the use of a simplified model is a common simplification to reduce the computational cost, although the reduced model may introduce significant errors in the simulation. Using the G-Scheme, the local structure of the local tangent space is characterized through the subspaces associated with the slow, active, and fast reactive scales. This specific feature can be of great significance in the analysis of the dynamics with the aim of achieving a low-dimensional description and allowing a time-scale-aware sensitivity analysis of the problem. Such analysis can be exploited to simplify/reduce/understand the reaction dynamics of interest. We have developed specific procedures to generate simplified mechanisms with an a priori known error for chemical kinetics processes, to analyze them in order to understand the role of the most important reactions, and to identify the most important reactions paths of the processes. The procedure is based on a G-Scheme Participation Index that makes use of a G-Scheme generated database. The effectiveness of the procedures to produce simplified mechanisms is demonstrated by applying them to the auto-ignition problems for homogeneous hydrogen/air and hydrocarbon/air mixtures.