The Magnus airfoil can convert wind energy into kinetic energy, driving the boat forward. The rotating cylinder at the airfoil's leading edge enhances lift and reduces drag, positioning it as a promising technology for boundary layer flow control. This study, based on the NACA0015 airfoil, employs Computational Fluid Dynamics (CFD) to investigate the effect of cylinder diameter on the aerodynamic performance of the Magnus airfoil. The Reynolds number is set to 4×10⁵, with an angle of attack of 18°, a rotational speed ratio of 1.4, and cylinder diameters ranging from 6% to 13% of the airfoil's chord length. Numerical simulations are conducted to analyze and compare the lift and drag characteristics, vorticity distribution, pressure distribution, and flow field structure for varying cylinder diameters. The results show that a high-speed rotating cylinder, when placed at the airfoil’s leading edge, effectively suppresses flow separation on the suction surface, delays boundary layer development, and enhances the overall aerodynamic performance of the airfoil. For the Magnus airfoil studied, the optimal diameter of the rotating cylinder at the leading edge is found to be 12% of the chord length.

Abstract
1. Introduction
2. Numerical Methods and Physical Models
    2.1 Air Resistance
    2.2 Physical Models and Computational Domai
3. Analysis of the Effect of Cylinder Diameter on Airfoil Aerodynamic Characteristics
    3.1 Lift and Drag Analysis
    3.2 Vortex shedding analysis
    3.3 Pressure coefficient curve analysis
    3.4 Streamline analysis
    3.5 Velocity analysis above the airfoil
4. Conclusion
References

• Shilong Li(School of Naval Architecture and Port Engineering, Shandong Jiaotong University, Weihai 264209, China)
• Haihua Lin(School of Naval Architecture and Port Engineering, Shandong Jiaotong University, Weihai 264209, China)
• Chengmeng Sun(School of Naval Architecture and Port Engineering, Shandong Jiaotong University, Weihai 264209, China) Corresponding author
• Fei Cao(School of Naval Architecture and Port Engineering, Shandong Jiaotong University, Weihai 264209, China)