Research On The Ship Wake Bubbles And Rogue Wave

During the voyage of ships, bubble films containing a large amount of bubbles so called whip wakes rise backward. The parameters of a ship wake depending on the size of the ship, draft and its weight. The research of ship wake bubble film can provide important basis for the realization of the ship’s location and its tracking hopefully. With the development of optical technology, optical characteristics of ship wakes are becoming a focus of study. In the field of optical research, optical technology plays an important role, which has been widely used for both military and civil purposes. The use of the optical properties of wakes line a new way for ship identification and its tracking.Ocean disasters caused by abnormal waves are a matter of great concern. However, there is a severe lack of related measured data and the history of relevant research is rather short. Abnormal waves are unusually large waves that occur accidentally. They are a special phenomenon of random waves, which are destructive to marine structures, sailing boats and coastal structures. Apart from the popular names of "crazy waves" and "killer waves", they are also known as "freak waves" and "rogue waves" in academic literature, which are translated into "freak wave" or "fierce waves" in Chinese. These un-standard names reflect that one can only see them from a certain perspective for a lack of understanding about why and how abnormal waves occur. Physical experiments or numerical simulation are of urgent to promote understanding of their basic characteristics as well as its formation mechanism, and to provide relatively complete references for researchers and marine engineers.The following six parts on ship wakes and rogue waves are investigated in detail in this dissertation.Firstly, references about ship wake and rogue waves are reviewed and analyzed systematically, the optical characteristics, the formations of air bubble films are elaborated, and the classification and detection of ship wakes are discussed.Secondly, based on laboratory studies, a physical model concerning the scattering property of air bubble curtain of ship wake is proposed. By comparison with the experimental results, the thesis proves that this model is reasonable and applicable in the study of optical characteristics of air bubble curtain.Thirdly, an experimental system is established for the laboratory research of laser scattering property of simulated ship wake, which proved to be reliable and meet the laboratory needs.Fourthly, the basic characteristics of turbulence and abnormal waves are studied. The experiments are carried out with turbulent conditions, as well as the laser scattering is studied under similar conditions.Fifthly, the purpose and significance of abnormal wave studies are introduced. Research status, causes of abnormal waves and its formation mechanism, as well as the characteristics are consolidated and summarized systematically.Finally, numerical simulation and analysis of abnormal wave are calculated and summarized under laboratory conditions. An abnormal wave physics simulator is built to simulate abnormal waves, rogue waves, the generation of rogue waves and its evolution are discussed in detail as well as.