Numerical Investigation on the Vertical Water-Entry of a Hollow Cylinder at Low Velocity

Based on the volume of fluid (VOF) multiphase flow equations, the k-e turbulent model and sliding mesh technique, the low speed vertical water-entry of a hollow cylinder was investigated numerically. The numerical results have a good agreement with corresponding experimental results and finer mesh independence. The results show that a jet flow induced by the through-hole provides a new connection between the inner and outer flow at the pinch-off time underwater. Furthermore, a little bubble on the top of the through-hole jet is created by the collision of the edge surface of the water column inside the cylinder. The initial water-entry speed has a significant influence on the inner cavity formation, the pinch-off depth, the through-hole jet ejection and the motion parameter during the vertical water-entry process.