Numerical investigations of ship hydroelasticity of a 20,000 TEU containership based on CFD-MBD method

In this paper, a fully coupled fluid-structure interaction method is proposed to study ship hydroelastic responses. A two-way coupling of CFD (Computational Fluid Dynamics) and MBD (Multi-Body Dynamics) solvers is applied to the numerical study of a 20,000 TEU containership. The flow field is solved using the RANS equations in OpenFOAM, while the structural dynamic responses are calculated using a beam model in MBDyn. Another opensource library, preCICE, is utilized for data exchange between the fluid and structural components in the coupling algorithm. The numerical results for the Response Amplitude Operators (RAOs) of ship motion and vertical bending moment (VBM) at midship are validated against experimental data under different wavelengths. Additionally, the hydroelastic responses are analyzed. The longitudinal distribution trends of the VBM under different wavelengths show a consistent pattern, with maximum hogging and sagging values occurring around the midship area. The maximum VBM responses are observed under conditions of lambda/L = 0.8 and lambda/L = 0.9, exhibiting significant high-frequency harmonic components. The comparison between numerical predictions of VBM for elastic and rigid ship body structures reveals a significant underestimation of VBM for rigid ships, even in relatively low sea conditions. This finding demonstrates the necessity of considering elasticity in the calculations of hydroelastic responses for ultra-large container ships.