Water entry of spheres with impact-axis channels

Abstract

Spheres are the most studied water entry projectile due to their symmetry and simplicity, but in practical applications, it is rare that an impacting body is perfectly spherical. Perturbations to the classical impactor are thus critical for aligning fundamental investigation with more advanced engineering applications. This study investigates the water entry of hydrophilic and hydrophobic spheres with through-channels along the water entry axis and producing deep seal cavities. The channels allow water to pass through the sphere to create a jet tailing the sphere and hastening cavity pinch-off. Channeled spheres produce smaller cavities than their intact counterparts and suppress the onset of cavity formation. Spheres with channels show similar drag coefficients as solid, intact spheres.