In the present work, breaking bow waves of KCS model are investigated. Different trim angles, i.e., 0 deg, 0.5 deg and 1.0 deg by bow are considered to investigate the trim effects on ship breaking bow waves. The Froude number of KCS is 0.35 for all the simulations and the predicted results are compared with the available experimental data. All the numerical simulations are carried out by self-developed CFD solver naoe-FOAM-SJTU. Ship resistance, wave pattern are presented. It is found that the predicted resistance agrees well with the experiment and bow wave is more violent when trim angle increases. Flow visualizations, such the vortex distribution around bow waves are given for further analysis. It is concluded that the present DDES approach with enough grids at bow wave region can give a better prediction of ship breaking bow waves.
Bow wave breaking is a very common phenomenon when a ship sailing in the open sea. The breaking bow waves are very complicated which include water overturning, plunging, water droplets, air entrainment, etc. In addition, the breaking phenomenon can be significantly changed when the ship is moving with different speeds or different trim angles. Thus, it is very essential to find an appropriate approach to predict the ship breaking bow waves. So far, many researchers have investigated the bow wave breaking based on numerical methods and also experimental measurements.
Olivieri et al. (2003, 2007) conducted experimental study of DTMB 5415 bow wave breaking. Wave elevation in breaking region and the wake flow in different cross sections were measured. It was found that high speed case can result in more severe breaking waves. Drazen et al. (2010) carried out experimental study of the breaking stern waves for a transom stern. Photos of different speed case show much difference on the breaking phenomenon. They also presented the wave height results in the breaking region. Gomit et al. (2015) performed free surface measurement of high speed ship based on the projection of laser beams on the surface of the fluid and on the use of a stereoscopic system. The wave height and velocity field near hull were quantitively investigated. Avci and Barlas (2018) carried out wave breaking experiment for high speed surface ship in towing tank. Photo study was conducted and a series of pictures for different speed (up to Fr=1.05) case were presented.