An Improved Yasutomi Correlation for Viscosity at High Pressure
Résumé
The Yasutomi temperature-pressure-viscosity correlation is attractive for elastohydrodynamic lubrication analysis because it does not require an equation of state for the liquid. However, the original Yasutomi correlation suffers from the appearance of a zero in the function describing the pressure dependence of the relative free volume thermal expansivity. When the original correlation is employed, a liquid with a high inflection pressure lacks the inflection in the predicted pressure-viscosity behavior and a liquid with a low inflection pressure is predicted to have two inflections. A new function removes these concerns and provides improved precision without the need for an equation of state. The improved function gives a more faithful representation of viscosity at even low pressures.