Nonempirical Free Volume Viscosity Model for Alkane Lubricants under Severe Pressures

K Falk and D Savio and M Moseler, PHYSICAL REVIEW LETTERS, 124, 105501 (2020).

DOI: 10.1103/PhysRevLett.124.105501

Viscosities. and diffusion coefficients D-s of linear and branched alkanes at pressure 0 < P < 0.7 GPa and temperature T = 500-600 K are calculated from molecular dynamics simulations. Combining Stokes- Einstein, free volume, and random walk concepts results in an accurate viscosity model for the considered P and T. All model parameters (hydrodynamic radius, random walk step size, and step frequency) are extracted from equilibrium molecular dynamics via microscopic ensemble averages rendering eta(P, T) a parameter-free predictor for lubrication simulations.

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