LAUSR

Abstract In this paper, the hydrodynamic characteristics associated with oblique water entry of two tandem spheres were experimentally investigated using high-speed photography. The results indicated that in the cavity formed by the first sphere, a suction effect due to the pressure difference between inside and outside the cavity was developed, which consequently led the second sphere to accelerate when it was totally submerged in the cavity. In addition, the first sphere was accelerated with a sudden expansion of the cavity radius due to the energy transfer effect associated with the collision of the two spheres, with a ring joint geometry observed, and the cavity finally broke up into two sections. Since the second sphere moved inside the cavity with less drag, it finally reached the first sphere and a second collision event was observed. Graphic abstract