On the water entry impact characteristics of high-speed vehicle with an Arbitrary Lagrangian-Eulerian method

This paper investigates the fluid-structure interaction process of high-speed vehicles during water entry using the Arbitrary Lagrangian-Eulerian method. Through mesh independence verification and comparison of numerical simulation results with experimental data and empirical formulas, the reliability and accuracy of the computational method are confirmed. The study comprehensively analyzes flow field pressure distribution, cavity evolution characteristics, and vehicle force features, evaluating the impact of water-entry angle, Froude number (Fr), and cavitator dimension. The results indicate that during water entry, the instantaneous impact forces are mainly concentrated on the wetted surface at the bottom of the vehicle and the plane at the head. The peak stress at the entry point is significantly higher than at other locations, and stress waves propagate along the vehicle body, concentrating at the hollow structure due to the structural characteristics. The change in water-entry angle does not significantly affect the decay of Fr for the vehicle, but increasing the water-entry angle leads to an earlier and larger peak stress at the mid-point monitoring location of the vehicle. In addition, the study also found that the stress level increases with the increase of the Froude number, resulting in larger high-stress areas and peak stresses. However, the cavity evolution at the same water-entry depth is essentially independent of the variation in Fr. With the increase in cavitator dimension, the water-entry load and cavity profile will also significantly increase, and vehicles with larger cavitator dimension will generate larger stress waves upon impact.