The top picture is velocity cloud, and the bottom picture is pressure cloud.At the same time, the suction surface and pressure surface are made, and the air flow on the suction surface is larger than that on the pressure surface. It can be seen from the data that the pressure on the surface with high speed is small, and the pressure difference between the upper and lower surfaces is upward. The maximum pressure is the windward point. Through CFD calculation, we can know the lift coefficient and resistance coefficient of NACA 4415