Taming Fire: Molecular Simulations of Combustion
The direct simulation Monte Carlo method allows to study combustion phenomena at the molecular level including state-to-state processes at conditions far from thermal equilibrium. The evolution of computational platforms and availability of highly scalable DSMC software open an opportunity for molecular simulations to enable improved combustion diagnostics and control. Such modeling is especially useful for combustion at high speeds and at the microscale due to nonequilibrium transport and chemistry. In this talk we review the necessary elements for a framework for applying the direct simulation Monte Carlo method (DSMC) to model combustion at the molecular level. Notably the standard DSMC approach employing Total Collision Energy (TCE) chemistry and Larsen–Borgnakke (LB) energy exchange models is not applicable for combustion simulations which are dominated by exchange and recombination reactions. A modified TCE-LB method is developed to ensure detailed balance and relaxation towards thermal equilibrium regardless of the internal energy relaxation rates. First, we consider a benchmark of H2–O2 premixed flame and compare with continuum modeling and experimental data. The DSMC simulations based on the extended TCE-LB framework are then applied for other combustion examples. In particular, we consider a novel microcombustor concept based on field-emission dielectric barrier discharge (FE-DBD). Field emission based microplasma actuators generate highly positive space charge that can be used to preheat, pump and mix reactants in microscale geometries and offer a promising solution to the problems associated with initiating and sustaining microcombustion.