This was achieved by coupling 1D-CFD codes, describing the flow in the intake and exhaust lines as well as in the fuel injection system ('FIS'), with 3D-CFD codes using the innovative Large-Eddy Simulation ('LES') technique, which can accurately reproduce the cycle resolved flow inside the combustion chamber.

The resulting multi-scale tools were then be applied to study the sources and effects of CCV in different gasoline engines. Work also concerned studying, in more detail, the effects of local factors, as early flame kernel growth at the spark plug and the interaction between the flow in the FIS and the fuel spray in a vessel, on CCV. The resulting improved understanding of CCV in gasoline engines was capitalised in the form of models able to reproduce the characteristics and effects of CCV in multi-cycle 1D-CFD simulations of operating points subject to cyclic variability.

Finally,the improved three industrial 1D-CFD codes incorporating these models was applied in case studies aimed at demonstrating the benefits to be expected from a better prediction of CCV in terms of CO2 and pollutant emissions under real driving conditions. The LESSCCV partnership brings together major European engine simulation software vendors, research centres and Universities from seven European countries. All internationally recognised for their expertise in engines and simulation.