Comparative study on numerical hydroelastic analysis of impact-induced loads

Ships and floating offshore installations are commonly exposed to impact pressures induced by waves. Suitable idealization of impulse induced slamming phenomena is possible by advanced “Fluid Structure Interaction (FSI)” models making combined use of principles of structural and fluid dynamics within the context of finite discretization methods. In such methods the fluid domain can be idealized using the “Finite Volume method (FVM)”, while the structural domain can be discretized by “Finite Element Analysis (FEA)”. Dynamic implicit solution strategies for FSI simulations are divided into one- and two-way coupling. In the former, the effect of deformation of the structure on fluid mesh deformation and the variation of added mass effects at different time steps of the numerical idealization may be neglected. Accordingly, the structure is assumed to be rigid and resulting pressures are applied as loading history onto the structural model. In two-way coupling methods, fluid pressures are transferred to the structural solver at each time increment and the corresponding structural deformation is transferred back to the fluid solver. Mesh morphing (also known as mesh adaption technique) may be utilized to ensure that the fluid mesh matches the deformed structural geometry. Recently, Lakshmynarayanana and Hirdaris (2020) presented a comparative study of nonlinear one- and two-way “Flexible FSI (FFSI)” methods for the case of global symmetric hydroelastic container ship responses. Results demonstrated that two-way FFSI coupling is essential in terms of idealising the influence of stochastically induced hydrodynamic actions on resonant ship responses. This paper presents FFSI modelling methods that may be used for the prediction of local slamming loads. As applicable, computations are assessed and compared for the cases of flat bottom plate and wedge-shaped structures against experimental results from Tödter et al. (2020) and KRISO (2014).