The flows in intake and exhaust manifolds of internal combustion engines play a major role in determining the different (volumetric, scavenging and trapping) efficiencies, indicated power, performance, emissions and establishing the flow field within the engine cylinder. When the gas flows unsteadily through these systems, both frictions, pressure and inertial forces are present. The relative importance of these forces depends on gas velocity and the size and shape of such systems. Traditionally, these flows were studied by means of the 1D gas dynamics equations where, the 3D phenomenon of the flow and the pressure wave's deformation, turbulence and viscosity were ignored or neglected. The thermodynamic (0D) approach was also used and where the important effect of fluid inertia related to the size of manifold components was ignored. In this study, the filling and emptying method, was completely revised and a new method (Inertial Capacitive Method ICM), based on the thermodynamic formulation of the filling and emptying method and on the fundamental equation of momentum conservation, is developed. The objective is then to take into account the fluid inertial effects on the fluid behaviour without the use of one-dimensional 1D code (due the computational times). In this objective, a computational fluid dynamics analysis is made in order to calculate the tuning parameters of the "inertial capacitive method" corresponding to the new model. In this study, it appears that the ignored inertial effects from the formulation of the filling and emptying method is the reason why this latter becomes only appropriate for the compact manifolds. To validate the new model, experimental investigation is carried out on a single-cylinder four-stroke engine. The volumetric mass flow rate of the engine is then calculated with the new model. The result is compared to the experimental one and a correct agreement is obtained.
