An improved higher-order moving particle semi-implicit (MPS) method has been developed to solve the problem of fluid–structure interactions for an elastic wedge entering calm water. The structural responses of the wedge with a reinforced tip were computed during the water entry. In the present method, the pressure gradient is corrected to guarantee the first-order consistency and to satisfy the conservation of momentum. Different particle spacings are used for the fluid and the structure. Convergence studies were carried out on particle spacings for the fluid and the structure and on a time step. A particle convergence index method was applied to evaluate numerical uncertainties in the improved MPS method. Validation studies were carried out on two elastic wedges with deadrise angles of 30° and 20° entering water at various velocities. Numerical solutions were compared with the results from the original higher-order MPS method and experimental data. The improved higher-order MPS methods led to better agreement with experimental data than the original one and significantly reduced the oscillations in numerical solutions.

In this paper, the ditching performance of a seaplane model on calm water and a uniform water current coupled with wind was numerically investigated. The overset grid technique was applied to treat the large amplitude of the body motions of the seaplane without leading to mesh distortion. The effects of the initial velocity and the initial pitch angle on the slamming loads and motion responses were investigated for the seaplane’s ditching on calm water. A good agreement with the experimental data on the velocity and angle was obtained. Besides ditching on calm water without the water current and wind, three more-complicated conditions were adopted, including the seaplane’s ditching on calm water with wind, a water current without wind, and a water current coupled with wind. The accelerations and impact pressures of the seaplane can be influenced by the wind or current. Water splashing and overwashing could be observed during the water entry process, with water overtopping the seaplane head or nose and flowing over the body surface. It can be concluded that the relative motion between the water and the seaplane model should be carefully controlled to avoid possible damages caused by the occurrence of overwashing.

This paper presents a numerical investigation into the hydrodynamic loads and motions experienced by two seaplane models during ditching in calm water and regular waves. The original bare model is susceptible to jet flows and wave overwash at the nose, which can adversely impact the aircraft's ditching performance. To address these issues, we introduced two biomimetic floats symmetrically to the original model and assessed their influence on the ditching dynamics. A comparative analysis was conducted on the accelerations, impact loads, and the coupled heave and pitch motions of both the original and the redesigned model equipped with floats during ditching in both calm waters and regular waves. For the wave ditching scenario, a detailed investigation of the slamming phase was first carried out, involving impacts at the wave's zero-crossing, crest, and trough. The cases with a variety of wave heights, wave lengths, and wave headings were evaluated. A particular focus was placed on understanding how the biomimetic floats affect the seaplane's performance during ditching in both calm and wavy conditions. The analysis of maximum accelerations and pitch angles during wave ditching revealed that slamming at the wave trough presents the most significant hazards. Additionally, the phenomena of gliding and wave overwash were identified as substantial risks under wave conditions. The results suggested that the biomimetic floats can effectively mitigate the maximum horizontal acceleration and pitch angle of the original model, enhancing the safety of ditching operations in both calm water and waves.