Transport Properties of Mie Fluids: Molecular Dynamics Simulations and Entropy Scaling

Transport properties of pure Mie fluids and Mie fluid mixtures were studied using molecular dynamics (MD) simulations and fluid theory (FT). The molecular simulation results are rigorously compared with fluid theory model results, i.e., entropy scaling (ES) in combination with a molecular-based equation of state (EOS). The agreement of the results from MD and ES + EOS is good overall. The following transport coefficients were studied: shear viscosity, thermal conductivity, self-diffusion coefficients, and mutual diffusion coefficients, including both Fickian and Maxwell–Stefan diffusion coefficients. The focus was on the variation of the repulsive Mie potential exponent (n = 8, 10, 12, 14, 16, 20, 36, 48 with the dispersive exponent constant at m = 6). Also, the influence of the dispersive Mie potential exponent was studied (m = 4, 5, 6, 7, 8 with the repulsive exponent constant at n = 12). Additionally, Mie fluids with (n, m) ∈ [(20, 8); (20, 4); (8, 4)] were studied. In total, 15 pure Mie fluids─for each more than 200 state points─were studied by MD simulations covering liquid, gaseous, and supercritical phases. Moreover, two binary mixtures with (n, m) ∈ [(12, 5); (16, 6)] and (n, m) ∈ [(14, 5); (20, 7)] exponents were investigated, focusing on the mixture diffusion coefficients. Therefore, the ES diffusion framework from Schmitt, S.; et al. [ Nat. Commun.2025, 16, 2611].was deployed. The predictions from the FT framework are in good overall agreement with the molecular simulation reference data, with the best agreement for self-diffusion coefficients. In all cases, a wide range of thermodynamic conditions, i.e., temperature, pressure, and composition, was investigated.