Numerical simulation on free motion response of a submarine induced by internal solitary wave

The internal solitary waves (ISWs) in the ocean carry huge energy and pose a serious threat to the safety of underwater vehicle. In order to obtain the dynamic response of the submarine under the action of ISWs, the amplified SUBOFF model was placed in a large numerical water tank with 5000x200x500 m dimension in which the water depth was 500 m. The Korteweg-de Vries (KdV) theory was adopted to simulate the generation of ISWs in the two-layer flow, and overset grid technology was used to ensure the grid quality during the submarine movement. The results show that before the ISWs peak reaches the position of the submarine, the submarine will move, which causes the submarine to sink, move laterally and pitch. The longitudinal velocity is obviously greater than the lateral velocity, and the submarine finally hits the water tank bottom. With the increase of the ISWs amplitude, the time needed for submarine to reach the bottom increases, and the pitching angle increases greatly. The ISWs amplitude has no effect on the motion trajectory of the submarine's center of gravity, and has little effect on the lateral and longitudinal velocity. With the decrease of submergence depth of the submarine, the time required for submarine to reach the bottom will also increase, and the motion trajectory will change, but the trend of change is basically the same. The submergence depth has little influence on the variation range of lateral velocity, longitudinal velocity and pitching angle.