A numerical simulation of the scavenging process in a two-stroke flat-piston model engine has been developed. Air enterns the cylinder circunferentially , inducing a 3-D turbulent swirling flow. The problem was modeled as a steady state axi-symetric flow through a cylinder with uniform wall temperature. The steady state regime was simulated by assuming the piston head fized at the bottom dead center. The calculation was performed employing the K-E model of turbulence. A comparison of the results obtained for the flow field with available experimental data showed very good agreement, and a comparison with available numerical solution revealed superior results. The effect of the Reynolds number, the inlet port angles, and engine geometry on the flow and heat transfer characteristics were investigated. It can be conclude that main parameters for the scavenging process are the Reynolds number, aspect ratio and type of the outflow exit.