A general tool for LTE thermochemistry for adiabatic nondiffusive fluid dynamics: applications to 2D planar discontinuity flows in SPH.

Chemical reactions in fluid dynamics deeply modify the flow physical conditions through both the contribution of the energy of reactions and the variation of the mean molecular weight and of the ratio of specific heats. This occurs typically on time scales largely much smaller than diffusive time scales of the produced chemicals, especially for shock waves coming from explosive events. In this work we show how it is possible to include a standing alone algorithm, dealing with both molecular and nuclear thermochemistry in the computational nondiffusive adiabatic flow dynamics in local thermal equilibrium (LTE) in an explicit scheme of integration of fluid dynamics equations, free of the adopted computational framework. In this paper, working in the Free Lagrangian GASPHER framework, belonging to the smooth particle hydrodynamics methods (SPH), some comparisons are made for planar discontinuity flows among reactive to the respective unreactive flow models, assuming the same initial physical conditions and simple chemical composition. Results show the importance of the role not only of the thermochemical reaction energy, but also of the mean molecular weight and of the ratio of specific heats.