The hydrodynamic performance of lifeboats is critical for the safety of passengers since several complex fluid-structure interaction phenomena could occur during the water entry phase. This paper, within a fully 3D Smoothed Particle Hydrodynamics (SPH) framework, is dedicated to investigating the hydrodynamic performance of a lifeboat by comparing with the reference results obtained via a Finite Volume (FV) solver. At first, the adopted 3D SPH model is briefly introduced with a multi-resolution consideration. Subsequently, a water entry benchmark of a cylinder is performed to validate the accuracy and stability of the utilized SPH model. Furthermore, the motion characteristics of the lifeboat with different water entry angles are investigated and discussed in detail. In particular, a comparative study is performed to assess the feasibility and accuracy of the SPH and FV methods in solving such problems. It is clearly demonstrated that thanks to its inherent Lagrangian nature, the SPH method can accurately capture the splashing jets and droplets during the water entry of the lifeboat. It is also indicated that for such problems, the air phase could somewhat affect the local flow fields behind the lifeboat, whereas it poses limited effects on the overall hydrodynamic performance of the lifeboat.


Water entry problems are one of the most important topics in ocean engineering since such phenomena involve extensive complex physical processes, e.g. hydroelasticity, turbulence, cavitation, multiphase effects, and Fluid-Structure Interaction (FSI) (Truscott et al., 2014). Among the water entry problems, the lifeboat water entry is tightly related to the safety of passengers when undergoing serious maritime accidents (van Dam et al., 2014). Therefore, this topic is worth receiving the attention of the ocean engineering community to offer a better design of lifeboats.

There is no doubt that for such complex FSI processes, experimental methods can be one of the most reliable strategies to investigate the water entry dynamics for different objects. Notwithstanding, two limitations block the wide application of this method in practical applications. One is that the scaling effect from model tests is inevitably encountered when transforming the model measurements into full-scale data (Lugni et al., 2021). Secondly, physical tests are always expensive and several extreme case conditions are hard to be reproduced in a laboratory. Therefore, the technique of Computational Fluid Dynamics (CFD) can be a more feasible strategy in engineering designs.

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