A smoothed particle hydrodynamics method for the fluid-structure interaction between waves and flexible net panels: modelling, validation and analysis

With the expansion of mariculture into offshore areas, analysing the hydrodynamic characteristics of net cage structures under wave action has become increasingly important. As the fundamental components of net cages, the fluid – structure interaction response of net panels is critical to the safe design and optimisation of cage systems. This paper proposes a coupled numerical model (SPH–LMM) that combines smoothed particle hydrodynamics with the lumped-mass method to simulate the hydrodynamic characteristics and dynamic responses of flexible net panels in waves. The net panel is discretised into multiple square plate elements, and its structural dynamics are described using the lumped-mass method. Variable resolution and an advanced particle-shifting algorithm are employed to significantly improve computational efficiency while maintaining numerical accuracy. The accuracy of the proposed model in predicting horizontal wave forces and motion responses under various wave heights, periods and net solidities is systematically validated through physical model tests. The average relative error of the peak horizontal wave forces was 10.45% for varying wave heights and 7.02% for varying wave periods. For net panels with different solidities, the maximum relative error was 9.32%. The results demonstrate that the SPH–LMM model effectively captures the interaction between waves and flexible net panels, with controllable errors in horizontal wave forces and good agreement between simulated motion trajectories and experimental observations. This study is the first to develop a fluid – structure interaction model between waves and flexible net panels within an SPH framework, in which a variable resolution algorithm is incorporated. The proposed approach provides an efficient and reliable numerical approach for the fluid – structure interaction analysis of flexible net-type structures in wave environments.