Mesoscopic simulation of nonequilibrium detonation with discrete Boltzmann method

Thanks to its mesoscopic nature, the recently developed discrete Boltzmann method (DBM) has the capability of providing deeper insight into nonequilibrium reactive flows accurately and efficiently. In this work, we employ the DBM to investigate the hydrodynamic and thermodynamic nonequilibrium (HTNE) effects around the detonation wave. The individual HTNE manifestations of the chemical reactant and product are probed, and the main features of their velocity distributions are analyzed. Both global and local HTNE effects of the chemical reactant and product increase approximately as a power of the chemical heat release that promotes the chemical reaction rate and sharpens the detonation front. With increasing relaxation time, the global HTNE effects of the chemical reactant and product are enhanced by power laws, while their local HTNE effects show changing trends. The physical gradients are smoothed and the nonequilibrium area is enlarged as the relaxation time increases. Finally, to estimate the relative height of detonation peak, we define the peak height as H(q) = (q(max) - q(s))/(q(von) - q(s)), where q, is the maximum of q around a detonation wave. q(s) is the CJ solution and q(von) is the ZND solution at the von-Neumann-peak. With increasing relaxation time, the peak height decreases, because the nonequilibrium effects attenuate and widen the detonation wave. The peak height is an exponential function of the relaxation time. (C) 2018 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute.