Wing-in-ground craft often encounter waves when flying over the sea surface, and the ground effect is more complicated than that of flat ground. Therefore, the aerodynamic characteristics of the NACA 4412 airfoil in proximity to wavy ground for a wide range of angles of attack is studied by solving the Reynolds Averaged Navier–Stokes equations. The validation of the numerical method is carried out by comparing it with the experimental data. The results show that the aerodynamic coefficients will fluctuate periodically when the airfoil moves over wavy ground at a small ride height. Except for the angle of attack of 0°, the fluctuation trend of aerodynamic coefficients at other angles of attack is the same. The analysis of aerodynamic fluctuation amplitude found that the medium angle of attack should be selected as the design cruise angle of attack for wing-in-ground craft. The time-averaged aerodynamic coefficients in the case of wavy ground are almost the same as those of flat ground. Hence, wavy ground mainly causes a fluctuation in aerodynamic coefficients. Considering the difference between aerodynamic coefficients at the angle of attack of 0° and at other angles of attack, the flow field structure at an angle of attack of 0° and 4° is analyzed. The results reveal the aerodynamic characteristics of the airfoil moving over wavy ground, which gives a deeper understanding of the ground effect in the conditions of wavy surface/ground. This has a certain guiding significance for the design of wing-in-ground craft.

Wing–in–ground crafts will face waves with different amplitudes when flying over the ocean, and the high amplitude situations are especially lack of exploration. Hence, the aerodynamic characteristics of the NACA 4412 airfoil in proximity to the wavy water surface for various wave amplitudes are inspected in this paper. By solving Navier–Stokes equations, the lift coefficients of the airfoil when the angle of attack ranges from 0° to 4° are obtained. The results show that the fluctuation amplitudes of aerodynamic coefficients increase remarkably with successive increases in the wave amplitude and might threaten flight safety. The flow fields at 0° with low and high wave amplitudes are investigated. It is revealed that the upward movement of the water surface is the critical factor for the change of aerodynamics, and the mechanism varies with different wave amplitudes. Comparison of the flow fields at 0° and 2° further indicates that the influence of high amplitude waves depends on the distance between the leading edge of the airfoil and the water surface. This study discovers the reasons for the different aerodynamic characteristics under various wave amplitudes and angles of attack, and is of great value for the design of wing–in–ground crafts.