Session: 12-02-03 Wave-Structure Interactions III

Paper Number: 127463

127463 - Breaking Bow Waves: Experimental and Numerical Investigations 

This study conducts an experimental and numerical study on the breaking bow waves generated by a 1:80 KCS ship model in a circulating water channel. The Froude numbers reaches high conditions of 0.377, 0.424, and 0.471. A binocular imaging system is employed to reconstruct the three-dimensional configurations of the bow wave surface. A multi-phase, multi-resolution SPH method with multi-GPU implementation and dynamic load balancing following the movement of the refinement regions is developed to simulate the breaking bow waves. A multi-background mesh is introduced, and the domain is regarded as a nested multi-domain with different resolutions. The bow waves breaking type changes from spilling along the wave crest to the intensely plunging in larger region with the increasing Froude number. Experimental and numerical results show the clear breaking patterns near the ship at the flowing stages of spilling, plunging, transition, and bore.

Based on the binocular reconstruction results, a novel method referred as Stereoscopic Foam Image Velocimetry (SFIV) is proposed to extract the instantaneous three-dimensional velocity of the foam in the breaking area. The distribution of the nominal time-averaged velocity shows that the main flow direction of the foam is the same as the incoming flow speed, with the flow near the ship's side moving away from the ship. The foam moving speed slows down and basically parallels to the incoming flow in the area behind the foam near the outside. The areas with large outward flow speed appears in the bore of the transition area at Fr = 0.471. The PSD analysis of the nominal turbulent energy shows that the power-law relationship of the nominal turbulent energy is less regular without clear periodic signal.

Analysis on the dynamic characteristics of the bow wave height is carried out in detail. The overall wave crest is relatively smooth with no fluctuations at the spilling stage. When the plunging wave occurs at Fr = 0.471, a certain raising area induced by the secondary jet is close in height to the area near the initial overturning breaking. The proper orthogonal decomposition method helps to study the dynamic characteristics of bow wave fluctuations. The result shows that the bow wave shape near the ship shifts from the feature of a long wave to the superposition of a series of short waves with the increasing Froude number.

Presenting Author: Hua Liu Shanghai Jiao Tong University

Presenting Author Biography: Hua Liu Professor of Hydrodynamics, Shanghai Jiao Tong University (1998- ); Director of Key
Laboratory of Hydrodynamics, SJTU (2008- ); Dean of Civil Engineering and Mechanics (2000-
2003); Vice Dean of Naval Architeture, Ocean and Civil Engineering (2004-2015); BA and MA
Hohai University (1984, 1987), PhD Shanghai Jiao Tong University (1991); Chair of Fluid
Mechanics Committee and Environmental Mechanics, Chinese Society of Theoretical and Applied
Mechanics (2015-2025); Member of Symposia Panel for Fluid Mechanics, International Union of
Theoretical and Applied Mechanics (2016-2024).

Authors:

Wenhao Tang Shanghai Jiao Tong University
Qian Wang Shanghai Jiao Tong University
Haocheng Lu Shanghai Jiao Tong University
Hua Liu Shanghai Jiao Tong University