Effect of Submarine Speed on Its Motion in Internal Solitary Waves

Although extensive research has been carried out on the load characteristics of fixed submarines in internal solitary waves, there is still insufficient understanding of the effect of submarine speed on its motion in internal solitary waves. A rapid calculation method for the motion response of a submarine (SUBOFF standard model) in internal solitary waves between two layers of fluid is established in this study, where the internal wave flow field is constructed based on the extended Korteweg-de Vries theory, and the load on the submarine is calculated using the Morison equation. The accuracy of the proposed method is verified by comparison with numerical results and experimental data. The results of the motion response of the submarine when encountering internal solitary waves at different speeds show that there is a significant nonlinear relationship between speed and vertical motion amplitude and maximum pitch angle. A critical speed is further found, beyond which the submarine experiences a secondary falling deep after the initial vertical falling deep.