The hydrodynamic behaviour of piston ring-cylinder liner is complex and it is difficult to predict its efficiency at the design stage. The piston ring has been the subject of many theoretical and experimental investigations from many viewpoints. In all these investigations, a known profile is assumed for the piston ring face and the minimum oil film thickness, hdrodynamic pressure distribution is computed under a multitude of simplifying assumptions. This project aims to develop a numerical model of piston ring dynamics and lubrication in internal combustion engines, it is currently estimated that the piston ring - cylinder bore friction accounts for up to 25% of the power loss in a typical engine, while oil transported to the combustion chamber by the piston and ring-pack contributes significantly to engine emissions. A profile of piston ring model was first developed to allow fast calculation of approximate piston ring dynamics. 

The finite difference is applied to solve the governing equations of lubrication of the piston rings and to calculate the hydrodynamic pressure. The ring is assumed to have a circular profile in the direction of motion. This profile changes with time because tilting of the ring with the engine cycle is taken into account.