Chemical reaction and diffusion: a comparison of molecular dynamics simulations with continuum solutions

Molecular dynamics simulations using the Lennard-Jones energy potential are compared with continuum solutions of reaction and diffusion in a dilute ga s. The reaction model is a passive one in which high-energy bath atoms crea te a species, at dilute concentrations, which may have a very fast consumpt ion reaction. This construction is designed based on typical fast reaction pathways involved in the fuel breakup in a hydrocarbon flame. Using reactio n rates and diffusivities obtained from the molecular simulations allows th e continuum solution to describe the reactive atom density spatial distribu tion with good accuracy. Based on this agreement, it is possible to estimat e which reaction rates will produce negligible diffusive spreading, and hen ce, which species might be assumed to be in chemical equilibrium in continu um reacting Row calculations.