Composite equivalent modeling of large-amplitude liquid sloshing in non-axisymmetric tanks

Large-amplitude liquid sloshing significantly affects the dynamic characteristics and motion stability of liquid-filled containers, rendering accurate prediction of liquid dynamics critical. In this study, a composite equivalent modeling method, based on dynamic liquid equilibrium positions, is developed for partially filled non-axisymmetric tanks. First, the definition and determination method of the dynamic equilibrium position are given, and the form, composition, and parameter determination method of the composite equivalent mechanical model are clarified. The dynamic equations of the equivalent system including the proposed model are derived, and solution methods for slosh force, moment, and liquid center-of-mass position are presented. Taking three-dimensional rectangular tanks and rounded-rectangular tanks as examples, the predicted results of liquid dynamic responses under transient large-amplitude excitation by the composite equivalent model are compared with simulation results for verification. The results show that the proposed composite equivalent mechanical model can efficiently predict the large-amplitude liquid sloshing behavior in normal gravity and low-gravity environments with high-prediction accuracy. The composite model exhibits significant advantages under violent sloshing compared with the traditional equivalent model. The proposed composite equivalent modeling method is universally applicable and, in principle, suitable for large-amplitude sloshing situations in arbitrary three-dimensional tanks.