Abstract
A comprehensive fluid dynamic model for the simulation of one-dimensional unsteady flows in engine ducts, from the air inlets to the exhaust outlets, is described. It can solve the fundamental conservation equations both by classical (Lax-Wendroff, MacCormack) and innovative (Conservation Element-Solution Element) shock-capturing numerical methods. Some results of an optimisation work carried out on the intake and exhaust systems of a four-stroke four-cylinder spark-ignition engine are reported in the paper. Comparisons between predicted and measured engine data are illustrated, with some examples of the model capability of tracking chemical species along the engine components and predicting the global tailpipe noise level radiated.