Different closure patterns of the hollow cylinder cavities with various water-entry velocities

摘要

The vertical water-entry processes of a hollow cylinder with three different velocities are investigated both numerically and experimentally. Three different closure patterns and flow characteristics of the air-entraining cavities induced by water-entry processes are discovered and discussed. Our results show that three different closure patterns appear with the increase of entry velocity, the deep-closure, the surface closure on the through-hole jet and on the geometry wall. Three high-speed regions also appear during the water entry process and their characteristics are different with various closure patterns. Besides, with the increase of water entry velocity, the velocity variation will vary from increase to decrease, but their water depths all increase linearly due to the short time and small variations of velocities.