Dynamic Adaptive Acceleration of Chemical Kinetics with Consistent Error Control

摘要

The incorporation of detailed chemistry in combustion simulations is challenging due to the large number of chemical species and the wide range of chemical timescales. The performance of acceleration methods such as tabulation/retrieval strategies may deteriorate dramatically when large variation in the accessed composition space is present. In this study, a dynamic adaptive approach is proposed to accelerate chemistry calculations, in which the in situ adaptive tabulation (ISAT) or dynamic adaptive chemistry (DAC) is dynamically selected based on the encountered composition inhomogeneity. The principle component analysis is employed to identify a low-dimensional subspace, in which the composition inhomogeneity of the computational cells is quantified through reconstructing the histogram of composition. ISAT is invoked for cells being in composition regions with high cell/particle numbers to avoid unnecessary tabulations. DAC is employed for the remaining ones by invoking on-the-fly reduction to generate small skeletal mechanisms for local thermo-chemical conditions and therefore accelerates the chemistry integration. The consistent error control of ISAT and DAC is also addressed such that a single error tolerance is employed to control the local incurred error in composition for these two methods. The proposed approach is validated in model engine simulations and the performance is analyzed.