Validating the darken relation for diffusivities in fluid mixtures of varying densities by use of MD simulations

Molecular Dynamics (MD) simulations have been carried out to determine the self-diffusivities, D<SUB>i,self</SUB>, of the pure hydrocarbons methane (C1), ethane (C2), propane (C3), and n-hexane (nC6) at various fluid densities. The MD simulations are in reasonable agreement with published experimental data. The influence of fluid density on both D<SUB>i,self</SUB> and the Maxwell-Stefan (M-S) diffusivities, Ð<SUB>ij</SUB>, in binary C1-C2, C1-C3, C2-C3, and C1-nC6 mixtures was also investigated. The MD simulations show that the M-S diffusivities in binary fluid mixtures can be estimated with good accuracy using the Darken relation