Study on the movement behavior of ping-pong ball on water surface under microgravity

In a microgravity environment, where gravity is almost absent, surface tension plays a dominant role in the behavior of fluid motion. The motion of fluids within storage tanks can lead to significant oscillations of the tank itself or even the entire vehicle, posing substantial safety risks. Solid foam particle anti-sloshing technology represents a novel research topic in addressing this issue. The anti-sloshing technology using solid foam particles is a novel research topic. In this experiment, ping-pong balls were used to simulate individual foam particles, and a transparent liquid tank was designed to observe their motion. Two different hydrophobic materials were applied to the surface of the balls to alter their surface tension in water. A drop tower was used to create a microgravity environment, and the motion of the balls in water under microgravity was recorded with a camera. Both static and dynamic analyses were conducted on the balls under normal gravity and microgravity conditions, considering water resistance, surface tension, and added mass forces. The control equations for the position and velocity of the ball’s center of mass were derived. The experimental results showed that under microgravity, hydrophilic balls tend to submerge into the water, while hydrophobic balls move upwards, away from the water surface. The equilibrium adsorption position of the hydrophilic balls differed significantly between microgravity and normal gravity conditions, with noticeable oscillatory movement in the vertical direction. The experimental results showed good agreement with the dynamic model.