A semi-analytical model for simulating the fluid-structure interaction from water entry to exit of 2D elastic bodies

This paper presents a fully-coupled semi-analytical model for fluid-structure interaction of 2D elastic wedges during continuous entry-to-exit motion. Different from conventional semi-analytical models limited to the entry stage, the present work integrates the Wagner model for the entry stage and the von Kármán model for the exit stage to simulate the whole process. Validations against benchmark tests show that the proposed method yields prediction errors below 10%, with simulation cost less than 10 min, showing higher efficiency compared with a conventional computational fluid dynamics method. A critical threshold of the dynamic loading factor R HS is identified as new physical insight beyond the entry stage. For R HS ≥ 2.0, structural safety assessment can rely purely on entry simulation. In contrast, for R HS < 2.0, modelling the exit stage is indispensable, particularly for structures with lower rigidity, smaller deadrise angles, higher initial velocities and greater entry depths. The maximum response for the entry-to-exit stage could rise by approximately 253% relative to the single-entry case for R HS = 1.0 at entry ratio H * = 0.5. This work offers an efficient tool and new understanding for hydroelastic slamming involving both entry and exit stages.