CFD–FEM analysis of ice-impact effect on the water-exit cavity and hydrodynamic characteristics of a ventilated vehicle

Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during high-intensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched marine equipment in low-temperature ice-prone waters. A computational fluid dynamics–finite element method (CFD–FEM) coupled framework was established to simulate bidirectional fluid-structure interactions during the water-exit process of a ventilated vehicle impacting ice in brash environments. Distinct evolution characteristics were revealed by comparatively analyzing the cavity, flow fields, hydrodynamic loading, structural deformation, and trajectory stability across three scenarios: ice-free, single-ice, and multi-ice. Furthermore, the position-dependent impact effects were characterized. The findings reveal that the impact, friction, and compression effects of ice induce bending and wrinkling of the shoulder cavity, aggravating its collapse and increasing the wetting of the vehicle, resulting in a substantial expansion of the high-velocity and vortex-dominated regions within the flow field, accompanied by more obvious water splashes. The impact of ice notably increases the kinetic energy dissipation of the vehicle during the cross-water stage and diminishes its motion stability. In the center-symmetric layout, the vehicle collides with ice only once, with high stress confined to the head. Conversely, the radial-offset layout causes secondary or even multiple collisions, resulting in high-stress areas on the shoulder of the vehicle, making it deflect and ultimately causing the tail cavity to tilt and become destabilized. The design of new vehicles suitable for ice-prone environments should focus on enhancing the impact toughness of the head structure and optimizing the surface shape design to improve the adaptability to low-temperature complex environments.