Interactional flow physics of freely falling sphere on stagnant water

Abstract The process of water impact and subsequent water entry of rigid objects is essential in engineering applications, including marine, offshore, and aerospace technologies. However, most studies have focused on the impact analysis of the object itself, with limited attention given to its interaction with water and the resulting flow dynamics. This work aims to address this gap by examining the effect of buoyancy on the hydrodynamics of a sphere in freefall, particularly its interaction with stagnant water. The investigation uses computational methodologies validated against experimental results to quantify flow and turbulence parameters, including pressure distribution, flow velocity, and other turbulence parameters for different buoyancy regimes. The study also explores the temporal evolution of the free surface profile to gain insight into the deformation and displacement of water resulting from the impact. The analysis reveals that buoyant spheres generate localized turbulent kinetic energy near the surface, while non-buoyant spheres induce higher, more dispersed turbulence. Pressure peaks at the bottom of the sphere, influenced by fall height but independent of density, while buoyancy affects the pressure distribution over time. Furthermore, buoyancy significantly influences the temporal evolution of pressure distribution and the formation of cavities compared to non-buoyant spheres, which exhibit more concentrated velocity streamlines. These results significantly affect designing and optimizing structures interacting with fluid environments, such as underwater vehicles and offshore platforms. Understanding the interplay between buoyancy and flow characteristics can enhance predictions of hydrodynamic behaviour, improving performance and safety in engineering applications.