Immersive human–computer interaction simulation and emergency buoyancy control of submerged body in the South China Sea internal solitary wave

Oceanic internal solitary waves (ISWs) produce strong nonlinear variations in density stratification and flow fields, posing considerable risks to submerged body navigation. In this study, high-resolution ISW data in the South China Sea were simulated using the Massachusetts Institute of Technology General Circulation Model (MITgcm), and a continuous three-dimensional visualization of ISWs was developed based on isopycnal depth extraction. A multi-degree-of-freedom dynamic model was employed to investigate the motion responses of a submerged body under different initial depths, propeller rotational speeds, and ballast-water discharge durations. For a high-amplitude ISW with an amplitude of 70 m, wavelength of 2000 m, and phase speed of −1.5 m/s, the maximum vertical displacement reached approximately −80 m at an initial depth of −150 m. At −250 m, the maximum pitch and yaw amplitudes were about 40° and 57°. Coordinated regulation of propeller speed and ballast-water discharge achieved a depth correction of 30.9 m and gradually restored stability after leaving the ISW environment. Furthermore, a fluid–structure coupled visualization framework with immersive human–computer interaction was established using a Logitech X56 controller and a VIVE Pro Eye headset.