A Molecular Dynamics Simulation of the Diffusivity of O2 in Supercritical Water

Equilibrium molecular dynamics simulations were carried out to study the diffusion process of oxygen in supercritical water (SCW). Both infinite-dilution diffusion and Maxwell-Stefan (MS) mutual diffusion coefficients were calculated. The differences between the simulated Maxwell-Stefan diffusion coefficients and those predicted by the Darken equation were examined. It suggests that the velocity cross correlation function plays an important role in the oxygen-SCW mutual diffusion. The Darken equation may not be valid in predicting the Maxwell-Stefan diffusion coefficients for this mixture.