Inline forces and bow wave height on a vertical cylinder moving in waves — Experimental study and CFD validation

Abstract

The aim of this paper is to investigate the inline force and bow wave height on a vertical cylinder moving at a constant forward speed in calm water and in regular waves. A series of physical model tests has been performed to investigate the effect the waves have on both the inline force and the bow wave height as well as to validate a Computational Fluid Dynamics (CFD) model that was developed using Caelus open source code. A stationary mesh was used in the CFD model and a new wave library was created based on the relaxation zone technique to incorporate the effect of adding a current with velocity equal to the speed of the moving cylinder while still generating the targeted wave field. The CFD results were compared to the physical measurements for the following cases: (1) generation of regular waves and current, (2) inline force and bow wave height on the cylinder moving in calm water and (3) inline force and bow wave height on the cylinder moving in regular waves. It was found from the model tests that both the inline force and bow wave height increased as cylinder speed increased. The maximum inline force and bow wave height measured on a stationary cylinder subjected to waves was amplified up to 9.6 and 2.7 times, respectively depending on the cylinder speed in case 3, which indicated a nonlinear relationship between the variation in maximum inline force and bow wave height due to wave–current interaction. The capability of the CFD model has been illustrated by the very good agreement (errors of about 3.0%) achieved with respect to the experiments for the different conditions of increasing complexity tested in this study.