The field of elastohydrodynamic lubrication (EHL) has gleaned little benefit from one-hundred years of high-pressure viscometers. Tribologists have sought substitutes for difficult viscometry [1], and a recent substitute is non-equilibrium molecular dynamics (NEMD) simulation. Attempts to predict film thickness and friction with the Eyring sinh-law for shear dependence have used alterations of the temperature and pressure dependences [1]. Unfortunately, the same errors are being made with NEMD. The shear stress capability of pressurized thin-film Couette viscometers has been significantly expanded. Film thickness and friction can be predicted from viscometry [1], and NEMD simulations do not provide the same constitutive behavior as viscometers except for very low-viscosity cases.
