To ensure validity over a wide range of thermochemical conditions, comprehensive kinetic mechanisms for the combustion of realistic fuels typically include hundreds of species and thousands of elementary reactions. However, much smaller subsets of species and reactions are often adequate to capture the dominant reaction pathways for specific local conditions over a short time span (typically taken to be the hydrodynamic time step in CFD calculations). Ansys Fluent offers the dynamic adaptive chemistry (DAC) method [367], [368] which makes use of this fact. The method reduces the comprehensive detailed mechanism to locally valid smaller mechanisms. This operation is performed on the fly (that is, during the dynamic simulation, at every time step). It is based on a skeletal mechanism-reduction method called Directed-Relation-Graph with Error Propagation (DRGEP) method [392], which offers very efficient and very accurate reduction. The Dynamic Adaptive Chemistry is similar to the Dynamic Mechanism Reduction (see Dynamic Mechanism Reduction), but only available with the CHEMKIN-CFD Solver. For details about the theory behind this method, see [367], [368], and [392].

For information about using the Dynamic Adaptive Chemistry method, see Using Dynamic Adaptive Chemistry with Ansys Fluent CHEMKIN-CFD Solver in the Fluent User's Guide.