Automated Thermochemistry for Combustion

Sarah Elliott, University of Georgia

Engine and kinetics simulations rely on accurate computation of thermochemical properties, such as enthalpies of formation, entropies, and heat capacities. For this reason, each simulation requires a union between ab initio electronic structure theory, transition state theory, classical trajectory simulations and the master equation. Not only is manual generation of the reaction mechanisms for these simulations a difficult and error-prone task, but the number of species that must be considered can easily grow to beyond tens of thousands even for the combustion of simple fuels. For each of these species, thousands of computations may be required to determine its equilibrium geometry and vibrational force constants.

We are developing a combustion chemistry code that automatically and holistically performs these computations to generate high-fidelity mechanisms. We have established a database so that as a calculation is performed for each species and level of theory, its relevant properties are concurrently stored. Combinations of extrapolations on database-stored and new computations will achieve an accuracy designed for the size of each system. We aim to exploit massively parallel computer architectures to simultaneously examine the hundreds or thousands of relevant chemical reactions. By exploring the kinetics of key combustion reactions, I will present the recent progress in the code's compatibility with the program EStokTP and demonstrate the effectiveness of this cutting-edge tool.

Abstract Author(s): Sarah N. Elliott, Murat Keceli, Ahren W. Jasper, Carlo Cavallotti, William H. Green, Stephen J. Klippenstein