Recent changes in the exhaust emission legislations obliged the automotive industry to reduce the emissions and improve the fuel saving. Stratified charge direct-injection engines were indicated as a convenient short-term solution to adapt spark-ignited engines to these requirements. In this context, the objective of this thesis was to evaluate the effectiveness of the intake system for a stratified charge spark-ignited direct-injection engines by means of a computational fluid dynamic tool. The effectiveness of the intake system in such engines is assessed by the tumble number. Therefore, the first objective of the project was to compare differences between transient and steady-state simulations in calculating the tumble number. Steady-state simulations are mostly used by companies since they require less computational power than transient simulations. However, the differences of the model between both types of simulations speak in favor of a clear advantage for transient simulation to calculate an approximation of the tumble number. The second objective of the project was to perform an enhancement of the mesh corresponding to steady-state model. This was performed by refining the mesh through different programs and studying the impact of each refinement criteria on the quality of the results.