No abstract

Energy is commonly dissipated in molecular dynamics simulations by using a thermostat. In non-isothermal shear simulations of confined liquids, the choice of the thermostat is very delicate. We show in this paper that under certain conditions, the use of classical thermostats can lead to an erroneous description of the dynamics in the confined system. This occurs when a critical shear rate is surpassed as the thermo-viscous effects become prominent. In this high-shear-high-dissipation regime, advanced dissipation methods including a novel one are introduced and compared. The MD results show that the physical modeling of both the accommodation of the surface temperature to liquid heating and the heat conduction through the confining solids is essential. The novel method offers several advantages on existing ones including computational efficiency and easiness of application for complex systems.

The aim of this article is to propose an original approach in modelling elastohydrodynamic lubrication (EHL), combining a classical model derived from continuum mechanics and a nanoscale investigation carried out by Molecular Dynamics simulations. In particular, nanoscale slip is numerically quantified and a semi-analytical model for surface slip variation with pressure, film thickness and sliding velocity is presented. A composite model involving both continuum mechanics and nanoscale effects allows for a better understanding of dimple formation and offers a new basis towards a physically based friction prediction. This tentative represents a new direction towards a more realistic modelling of lubricated contacts with ultra thin film for the present industrial needs.