C N
Ansys Employee

Hello,

The physics behind the steel ball bouncing back on the water surface initially and then sinking into the water at a greater height compared to a smaller height is due to the law of conservation of energy because at a greater height you have more potential energy stored, so when you drop the ball from a greater height the potential energy gets converted to kinetic energy and the ball gains more velocity which is more than sufficient to overcome the shear resistance of the water surface so it bounces back initally and then later sinks into the fluid. At a smaller height there is less potential energy stored so less velocity is obtained during the conversion of potential energy to kinetic energy which is not sufficient to overcome the shear resistance of the water surface since velocity is less there is more pressure drag is experienced and it sinks into the fluid. For a more detailed in depth understanding Particle Velocity, Particle Force balance and Particle torque balance can be analysed in which one of the most important force is the drag force which depends on particle relaxaton time and particle relative reynolds number.But in your case Qualitatively speaking even at both the heights the steel ball will sink inside the water. Yes Macroscopic particle modelling can be used.

Thanks