回転する撥水性円柱が水没するときの 運動挙動に及ぼす濡れ性の影響

–　回転円柱の運動方程式に基づく一考察　–

抄録

This study aims to investigate wettability influence on the motion of a rolling circular cylinder entering water. The movement of the rolling cylinder after the water-entry was taken with a high-speed camera. As a result, the asymmetry was observed in the splash and the cavity caused by the hydrophobic cylinder entering water. In particular, an intriguing phenomenon visualized is the fact that the wettability can affect the movement direction of the rolling cylinder, i.e., the rolling cylinder having a hydrophobic surface moves to the opposite direction to the hydrophilic cylinder within the present experimental conditions. This study also formulated an equation of motion (EOM) of the rolling circular cylinder, assuming that the drag direction acting on the cylinder deviates from the moving direction due to the asymmetry of the splash and the cavity. The EOM formulated in this study can be found to deduce the movements of the hydrophobic and hydrophilic cylinders.