Effect of Shock Strength on the Structure of H 2 /O 2 Reactive Shock Waves

We report on the effect of shock strength on the structures of reactive shock waves in stoichiometric gaseous H₂/O₂ mixtures by using non-equilibrium reactive molecular dynamics simulations. In each simulation, a shock wave is generated by a piston moving in a square duct. Six cases are considered: reactive shock waves with Mach numbers of 2, 4 and 5.6, and inert shock waves with the same Mach numbers in which H–O chemistry is artificially deactivated. In all cases, the shock front of H₂ is formed ahead of that of O₂ to create fluctuations of the mixture ratio in the shock region. The separation of the two shock fronts increases with shock strength and is also enhanced by exothermic chemical reactions. The velocity profiles show that the shock thickness of the mixture decays with the shock strength as expected, while the H₂ shock is globally thicker than the O₂ shock.