Mie 16–6 force field predicts viscosity with faster-than-exponential pressure dependence for 2,2,4-trimethylhexane

• Published in: Fluid phase equilibria Vol. 495; pp. 76 - 85
• Main Authors: Messerly, Richard A., Anderson, Michelle C., Razavi, S. Mostafa, Elliott, J. Richard
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-09-2019
• Subjects: Green-Kubo; Industrial Fluid Properties Simulation Challenge; Molecular dynamics simulation; Pressure-viscosity coefficient; Uncertainty quantification; Uncertainty quantification; Pressure-viscosity coefficient; Molecular dynamics simulation; Industrial Fluid Properties Simulation Challenge; Green-Kubo
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/j.fluid.2019.05.013

In response to the 10th Industrial Fluid Properties Simulation Challenge, we report viscosity (η) estimates obtained with equilibrium molecular dynamics for 2,2,4-trimethylhexane at 293 K and over a range of pressures (P) from 0.1 MPa to 1000 MPa. The Mie Potentials for Phase Equilibria (MiPPE) force field is utilized in this study, as a previous study demonstrated that it provides reliable estimates of η with respect to P. Whereas most studies report only the uncertainties associated with random fluctuations in the simulation output and subsequent data analysis, we investigate the effect of uncertainties arising from the force field non-bonded and torsional parameters. The pressure-viscosity coefficient as a function of pressure is reported for several different empirical models, namely, McEwen-Paluch, Roelands, Roelands-Modified, and Barus. Although the uncertainties increase substantially with increasing pressure, cross-validation model selection provides quantitative evidence supporting faster-than-exponential, a.k.a. super-Arrhenius, behavior with an apparent inflection point in a log10(η)-P plot around 200 MPa. Near-quantitative agreement between simulation results and new experimental data is achieved for P≤600 MPa, followed by significant over prediction at higher pressures.