Design of Breakwaters to Minimize Greenwater Loading on Bow Structures of Fixed Floating Vessels

Abstract

Greenwater (splashing of water on the deck) loading is a classical problem faced by the designer of ship-shaped vessels, which becomes even worst when the vessel operates at harsh weather conditions for an extended period. Installation of breakwaters on the deck can play a crucial role in minimizing this impact. However, research on the design and optimization of the breakwater is still at its infancy, and this study aims at shedding further light on this area by proposing and analyzing the effectiveness of three breakwater designs on a fixed box-shaped vessel. Commercial CFD software is used for this investigation. However, the design model (without breakwater) was validated at first against experimental results of green water splashing, before performing the actual simulations with proposed breakwater design. A vertical plate is used as the deck structure, and greenwater pressure at several locations on that plate is measured to compare the effectiveness of various breakwater designs. Overall, breakwaters with openings (perforations, grillages etc.) found to be more effective in minimizing the pressure generated by the greenwater. Nevertheless, there are significant rooms for improvement on breakwater designs, and some topics for further research are also suggested in this regard.

On the Evolution of Different Types of Green Water Events

“…The features of green water on a deck can drastically change when the structures have structural protections, such as bulwark plating at the start of the deck, as recently shown by [37]. Other types of protections on the deck of marine structures, such as those reported by [52,53], may also change the propagation of green water events.…”

“…Perhaps, in further comparisons regarding the initial stages of some types of events, such as PBD and HF-types, the use of multiple-valued water surfaces measurements would allow more detailed validations. This type of measurement may also be of importance in green water cases when there are protective structures on the deck (e.g., [37,52,53,69]). Third, it is known that several types of green water events can entrap volumes of air during the initial stage of shipping in rectangular-type structures (e.g., PDB-types [2,9,11,13]).…”