A RANS/LES investigation of the effects of a ventilation cavity on multiphase flow and motion characteristics

Ventilation can effectively reduce the impact load and flow interference of vehicles passing through the free surface. This study analyzes the effect of a ventilation cavity on the structure and motion characteristics of multiphase flow. It employs the improved delayed separation vortex simulation model, the Schnerr–Sauer cavitation model, the volume-of-fluid multiphase flow model, and an overlapping grid. The results revealed that as the ventilation volume increases, the initial growth rate of the bubble length remains approximately constant, increasing later at higher ventilation volumes. Simultaneously, the generated deflection torque significantly reduces the flow interference phenomenon caused by the narrow water gap between twin-engine vehicles. However, the effect of reducing the load and increasing the stability of ventilated vehicles under different axial launch spacings remains generally moderate, primarily improving the load's pulsation characteristics, while the overall enhancement in vehicle motion stability remains limited.