Abstract: In stratified oceans, large-amplitude internal solitary waves (ISWs) frequently occur, often accompanied by strong shear flows during their propagation. These waves can exert sudden loads on underwater bodies, potentially causing instability and leading to the danger of “falling deep” To investigate the load characteristics of fixed submerged bodies under the influence of these waves, computational fluid dynamics (CFD) methods were employed for numerical simulations. A numerical wave generation method based on the strongly nonlinear aHOU theory was developed specifically for large-amplitude ISWs, generating waves within the computational domain using a velocity inlet approach. This established a numerical model for the interaction between largeamplitude ISWs and fixed submerged bodies. The accuracy and reliability of the model were validated by comparing its results with experimental data. Additionally, regression analysis and control variable methods were utilized to explore the effects of wave amplitude and submergence depth on the load characteristics of the submerged body under ISWs. The study characterized the load properties of the submerged body in three scenarios: above the ISW surface, traversing the wave surface, and below the wave surface. Results indicate a quantifiable linear relationship between the positive amplitude of the horizontal load and wave amplitude, while the duration of the vertical force exerted by ISWs is related to submergence depth. Under the condition where the submerged body traverses the wave surface, the primary component of the vertical force is identified as the pressure differential force. This study provides a theoretical foundation for understanding the issue of “falling deep” in underwater bodies due to internal waves.

Key words: Submerged body, Internal solitary waves, Loads, Numerical simulation