Simulation-Based investigation of the effect of operating conditions on the tribological behavior of SiO2-enhanced engine oil

Abstract

This study investigates the effect of SiO₂ nanoparticles on the tribological performance of 10W-30 engine oil under different operating conditions using a simulation-based approach in MATLAB/COMSOL multiphysics. Four nanoparticle weight concentrations (0.01%, 0.02%, 0.05% and 0.1%) were analysed at rotational speeds of 100, 250 and 400 RPM under a constant load of 10N. A mathematical model combining the Reynolds equation and asperity contact mechanics was developed to evaluate the hydrodynamic and asperity load contributions. Results demonstrate that increasing SiO₂ concentration significantly enhanced the lubricant's performance: the coefficient of friction decreased by up to 32% at 0.1% SiO₂, film thickness increased from 0.45 µm to 0.68 µm up to 51%, and load-carrying capacity improved by 35%, with more pronounced effects at higher rotational speeds (RPMs). Limitations of the model include assumptions of idealized asperity contact and uniform nanoparticle dispersion, which were addressed via mesh convergence tests and validation against experimental trends. Mesh validation confirmed good agreement between simulated film and hydrodynamic pressures, supporting the model's reliability.