Combined experimental and numerical investigation of multiphase flow during water entry of spheres with different densities

•A combined of experimental and numerical investigation is used in the research.•The numerical method is based on the N-S equations with wettability.•The splash and cavity of water-entry spheres with varied densities are studied.•The motion and hydrodynamic characteristics of the sphere are analyzed.•The total hydrodynamic force and drag force are compared and discussed. The objective of this work is to investigate the cavity dynamics during water entry of spheres with varied structural density by a combined experimental and numerical method. Similar to the observations of Aristoff et al. (2009), the cavity types are further classified considering the relationship between the splash and cavity, then a map of cavity types in a Froude number and density ratio (Fr-m*) plane is concluded. It is found that the critical velocity of each cavity type is reduced with increasing density ratio of the impact sphere, and the rebound phenomenon only forms in the case of low-density m*