Experimental and numerical study on cavity dynamics during near-water-surface skipping motion of a non-spinning disk

In this paper, we present a comprehensive set of experimental and numerical studies on the near-water-surface skipping motion of three-dimensional, non-spinning disks. Qualitative analyses were conducted on the experimental results to examine the effects of inclination angle on cavity evolution. Additionally, numerical results are utilized to study the impact of the attack angle on hydrodynamic forces and motion characteristics of the disk. Key findings of this study include the following: (1) an asymmetric cavity will be formed during the near-water-surface skipping motion of the disk; (2) two distinct cavity shapes, U-shaped and W-shaped, emerge under varying initial inclination angles; (3) decreasing the inclination angle reduces the angle between the splash and the water surface, improving the possibility of a successful skipping motion; (4) disks with excessively large positive or negative inclination angles tend to dive into the water; (5) an instantaneous significant reduction in inclination angle during impact results in dual peaks of vertical force, with corresponding increases in hydrodynamic forces and pitching moments as the impact angle increases; and (6) disks with extremely small impact angles are prone to overturning and diving into the water.