An Experimental Study on the Cavity Evolution of a Continuous Entry of Sphere Through a Viscous Fluid into Water

In the present paper, cavity evolution of a continuous entry of sphere through dimethicone into water was studied experimentally in DLUT (Dalian University of Technology) Marine Hydrodynamics Laboratory. High-speed video was used to capture the movement sequences of the sphere and cavity evolution. Firstly, we conducted a vertical entry case of the sphere dropped from 0.7m above the free surface. After the entire sphere submerged under the free surface, the splash crown and subsurface air cavity began to form. It was important to note that a continuous cavity appeared at the interface of the dimethicone and water. Furthermore, the influence of various parameters, specifically the thickness of the dimethicone layer, were studied. One of the most interesting results was that relationship was found between the thickness of the dimethicone layer and the pitch off time. The interaction between the sphere and the cavity was also noted. These would help to understand the water entry problem with the change in fluid properties.