Fluid–structure interaction modeling of sloshing dynamics with flexible baffles: design insights for aerospace applications

This study presents a comprehensive analysis of sloshing dynamics in rectangular tanks equipped with flexible anti-sloshing devices (ASDs), focusing on how varying levels of baffle elasticity influence fluid–structure interaction. Three configurations, differing in baffle sub- mergence relative to the free surface, are investigated using a coupled numerical approach that integrates the Finite Element Method (FEM) for structural modeling and the Finite Volume Method (FVM) with a Volume Of Fluid (VOF) approach to free surface reconstruction for fluid dynamics, connected through a two-way partitioned coupling strategy. Numerical decay tests are conducted to examine the damping characteristics and sloshing frequencies of the system. A reduced-order acoustic-structural model is introduced to predict fundamental frequency shifts associated with different baffle flexibilities and submergence levels. The reduced model’s predictions show sufficiently good agreement with full order simulations, demonstrating its value as an efficient, low-cost design tool. The study reveals that enhanced vortex formation due to the elastic restoring motion of the flexible baffle aligns with the analysis of the energy dissipation rate evolution in the fluid, indicating that increased vorticity plays a critical role in damping. This supports the potential of flexible ASDs to match or exceed the damping performance of rigid counterparts while significantly reducing added weight.