Freak wave is a type of extreme wave that threats ships and offshore structures. However, few researches have be conducted on the ship motion response caused be freak waves. In order to better understand the influence of freak wave, heaving and rolling of a container ship caused by freak waves are studied in this paper. Simulations of the wave-ship interaction in beam sea are conducted in a numerical wave tank using CFD method. The interaction process, heaving and rolling motions of the ship are obtained and analyzed, indicating that ship motion responses are greatly affected by freak waves.
Container ships are vessels used to transport large quantities of non-bulk goods over a long distance. Over 90% of all non-bulk goods are transported by container ships worldwide. However, this also puts forward higher requirements for the safety of the container ships. Container ships may heave and roll greatly in beam sea when they encounter huge waves such as freak waves. Ships generally encounter various waves while navigating, which are called beam sea when they encounter waves 75 to 105 degrees on the left and right sides. The beam sea mainly produces lateral movement, in which rolling is the main one. Once large rolling occurs, not only the normal operations of the ships can be affected, but also the safety of the ship and crew may be threatened. However, research on motion response of container ships under huge waves like freak waves is still insufficient.
Freak wave, also known as rogue wave, is a kind of strong non-linear extreme wave under severe sea states, with characteristics of large wave height, prominent peak and concentrated energy. In order to study freak waves and the interaction between freak waves and ships and offshore platforms, researchers proposed varies of freak wave models. Kriebel et. al. (2000) put forward the superposition model of double wave train to generate freak waves. Pei et. al. (2007) proposed a three- wave train superposition model based on Kriebel train model. Peregrine et. al. (1983) proposed the Peregrine respirator solution model. Chabchoub et. al. (2013) carried out wave making experiments based on Peregrine respirator solution model.
