Cavity collapse associated with oil entry of steel spheres

The collapse of air cavity towards the liquid surface that occurred immediately after deep seal following vertical entry of steel spheres into a pool of oil, was experimentally investigated. The vertical displacement between the pinch-off depth and the cavity base during the time when the cavity was collapsing towards the surface, was regularly measured and analysed using images taken from a high-speed camera. Furthermore, some phenomena associated with the upward oil jet generated during cavity collapse were also described and briefly studied. The results suggested that the rate of cavity collapse towards the surface, and the time taken for the lower part of the oil jet to reach surface level, were dependent on both the inertial and gravitational forces of the spheres.