Interactive visualization fusion and three-dimensional trajectory analysis of internal solitary waves and submersible in the South China Sea

Internal solitary waves (ISWs), as strongly nonlinear waves in stratified oceans, can induce large isopycnal displacements and intense shear flows, posing significant threats to the navigation safety and motion stability of submersibles. This study employs the Massachusetts Institute of Technology General Circulation Model to simulate ISWs in the South China Sea. A dynamic isopycnal surface reconstruction method, an adaptive level-of-detail strategy, and interactive color mapping are developed to enable real-time three-dimensional visualization of ISWs and rapid identification of wave troughs. A motion simulation algorithm is then applied to investigate the responses of a submersible under different initial depths, velocities, and propeller rotational speeds. After validation against reference results, simulations show that, for a stationary submersible encountering continuously stratified ISWs with an amplitude of 150 m and a wavelength of 2000 m , the maximum downward displacement reaches approximately -131.02 m , comparable to the displacement of the corresponding isopycnal surface. For a moving submersible, the initial kinetic energy is rapidly dissipated by the ISW-induced flow field, and the maximum pitch angle reaches approximately 28° at an initial velocity of 10 m/s . Under continuous propulsion, the submersible operating at 60 rpm still experiences a short-duration negative horizontal displacement, whereas at 120 rpm it reaches its maximum diving depth before the corresponding isopycnal trough, with a maximum downward displacement of approximately -124.67 m . The proposed framework realizes coupled visualization of ISWs and submersible motion, providing an efficient tool for real-time analysis of fluid–structure interactions in complex ocean environments.