Heat and Mass Transfer in Reacting Mixtures: Molecular Dynamics and Kinetic Theory Approaches

Transport properties of a binary H-2-H mixture with strongly-non-equilibrium dissociation reaction are studied on the basis of two approaches: kinetic theory and molecular dynamics. The gas in the thermostat under the action of temperature gradient is considered. Mass diffusive and measurable heat flux are obtained in the non-equilibrium molecular dynamics simulations; the transport coefficients are extracted from the fluxes using the constitutive equations given by irreversible thermodynamics. For the same conditions, the transport coefficients and the corresponding fluxes are calculated using the modified Chapman-Enskog method for the rarefied flows with non-equilibrium chemical reactions. While the qualitative agreement between the results obtained using the two approaches is found, quantitative differences are however noticeable. The discrepancy in the heat conductivity coefficient is not large but is significant for diffusion coefficients. Possible sources of discrepancies are discussed.