Numerical investigation of the influence of surface wettability on water entry of spheres

The water-entry problem is a complex multiphase hydrodynamic that directly related to many engineering applications and natural phenomena, such as torpedo airdrops, seaplane landings, ship slamming. Therefore, studying the influence of microscopic properties object surface on macroscopic phenomenon during water entry necessary. In this study, volume fluid model continuum force models are coupled establish flow numerical method for objects considering wettability. effect wettability evolution cavity, flow-field structure, characteristics analyzed in detail. results show movement liquid film formed sphere at early stage key formation cavity. For hydrophobic spheres, separates near equator sphere, air enters it form At moment pinch-off, pressure lower cavity increases, which generates pushes accelerate fall, higher spheres with smaller density ratio. structure shows both rotational shear effects play dominant role field hydrophilic follows contact line along converges top an upward jet.