Water entry of manta ray-inspired flexible submersible based on a WCSPH-SPIM model

Based on a coupled weakly compressible smoothed particle hydrodynamics (WCSPH) and smoothed point interpolation method (SPIM) framework, this study numerically investigates the water-entry behavior of manta ray-inspired flexible submersibles. The effects of entry velocity, inclination angle, and elastic modulus on hydrodynamic impact response and structural deformation are systematically analyzed through two-dimensional water-entry simulations. The results show that the entry velocity primarily governs the intensity of hydrodynamic impact loading, whereas the inclination angle mainly affects the spatial distribution of pressure and the evolution characteristics of the flow field during oblique water entry. In addition, decreasing structural stiffness enhances the flexible deformation response of the submersible and significantly modifies the local fluid–structure interaction process. The present study provides a numerical reference for understanding the coupled hydrodynamic response of flexible trans-medium submersibles during water entry and offers theoretical support for the structural design and attitude optimization of biomimetic underwater vehicles.