Experimental and numerical studies on vertical water entry of a cylinder under the influence of current

Abstract

When a moving object penetrates the free surface, it is often accompanied by complex multiphase flow phenomena. In this work, the complicated impact cavity and flow characteristics of water entry by a cylinder are investigated both experimentally and numerically for different current velocities. A high-speed photography technique is employed to capture the cavity contours under both calm water and flowing water. Under the same working conditions, a three-dimensional simulation using a volume of fraction model is conducted to provide detailed flow field structures and motion behaviors for experimental results. The primary results are as follows: the effect of current causes the cavities to no longer develop symmetrically. The cavity on the upstream side is compressed close to the cylinder surface, while the cavity on the downstream side expands. The asymmetrical distribution of cavities causes different wetting states on both sides of the cylinder. The ensuing pressure difference prompts the cylinder to deflect which is quite different that without considering current. Vortices generated on the upstream side disappear faster, while those generated on the downstream side expand significantly along the flow direction.