Water-entry hydrodynamics of a trans-media flying wing

Inspired by the water-entry strategies of amphibious birds, this study introduces a bio-inspired flying wing for efficient transition from air to water. A volume-of-fluid multiphase flow model coupled with the shear stress transport k–ω turbulence model is employed to investigate the two-phase flow dynamics during water entry. The stability, hydrodynamic loads, and energy efficiency of the proposed configuration are examined by systematically varying the contraction ratio, structural density, water-entry angle, and velocity. Results show that flying wings with smaller aspect ratios and lower densities, entering water at lower velocities and larger angles, exhibit slower attitude variations and improved stability, but at the cost of higher energy loss. Furthermore, increased wing contraction and reduced entry velocity significantly mitigate the impact loads. To describe these specific relationships, we define a coupling multi-parameter impact index and a comprehensive stability metric, demonstrating a strong linear correlation. These findings advance our understanding of biological water-entry behavior and provide valuable guidance for the design of bio-inspired flying wings in trans-media vehicles.