Abstract
The purpose of this study is to investigate the dynamic behavior of a pair of spheres with different wettabilities penetrating into a water bath. The visualization technique employs a high-speed camera. An air cavity is formed behind the spheres under certain conditions. The maximum cavity depth and the time required for the cavity to break up are measured and compared with their respective empirical equations proposed previously for a single poorly-wetted sphere. These two quantities can be correlated in terms of the Froude number similitude
