Smoothed particle hydrodynamics simulation of sloshing dynamics considering internal–external fluid–structure interactions

Liquid tank sloshing presents a complex fluid–structure interaction (FSI) challenge in marine engineering, particularly when bidirectional coupling between internal slosh dynamics and external hydrodynamic interactions occurs. This study aims to develop an improved Lagrangian meshless smoothed particle hydrodynamics (SPH) framework for two-dimensional rectangular tanks, with a novel focus on bidirectional FSI through synchronized wave field excitation and tank motion. Advanced pressure stabilization techniques are integrated into computational methodology. Density filtering and dynamic boundary particle formulations are included to resolve transient slamming pressure characteristics. Validation against forced excitation benchmarks and wave generation experiments confirm the model's capability in capturing nonlinear free-surface behavior. Comparative analyses reveal that coupled FSI conditions induce significant pressure peak attenuation compared to conventional forced vibration scenarios, with wall pressure distributions exhibiting distinctive aperiodic fluctuations. Notably, the slamming pressure magnitude under resonance conditions measures merely 39% of decoupled forced excitation values, demonstrating substantial energy dissipation through bidirectional FSI. Within the constraints of two-dimensional modeling, these findings provide key insights for the design of high-fill-rate containment systems and can offer references for engineering issues such as liquid tank sloshing.