An innovative, highly efficient and expertise-free mechanism reduction method: important species identification through species’ participation in element fluxes

An innovative kinetic mechanism reduction method, Species’ Participation in Element Fluxes (SPEF), is developed in this study. It utilises species’ participation in element fluxes to evaluate the importance of the species during the combustion process. The SPEF method has two main benefits: (1) it targets at C, H and O elements instead of pre-selected target species and has only one variable threshold on species importance, which makes it feasible to obtain satisfactory skeletal mechanisms for researchers even without any mechanism reduction expertise; (2) it shows significantly low time complexity, which helps to achieve high computational efficiency in the reduction process. Three mechanisms with different sizes were reduced and utilised to investigate the reduction capability of the SPEF method. It has been observed that the reduction performance of the SPEF method is competitive with other widely used directed relation graph with error propagation (DRGEP), path flux analysis (PFA) and global pathway selection (GPS) methods. The effectiveness of the SPEF method was further demonstrated by extensively validating the SPEF-reduced mechanisms against the detailed mechanisms. In addition to the application to static reduction, this method could also be easily utilised for dynamic reduction to save computational efforts in reactive flow simulation while retaining satisfactory accuracy. An example was given by integrating the SPEF method into the KIVA4 code package to dynamically reduce chemical mechanisms in 3-D engine simulations. It has been proved that even for 3-D engine simulations with a highly compact mechanism, computational cost can still be saved in a considerable scale using the SPEF method.