Experimental and Numerical Analysis of the Influence of Fluid–Structure Interactions on the Dynamic Characteristics of a Flexible Tank

This study investigates the impact of two-way fluid–structure interactions (FSIs) on the dynamic behavior of flexible liquid storage tanks. A hybrid approach, integrating the finite volume method (FVM) with the finite element method (FEM), referred to as FVM/FEM, was employed to simulate the behavior of flexible water tank under seismic loading.

The fluid domain was modeled using FVM, while the structural domain was represented through FEM. The FVM/FEM model offers essential insights into modeling two-way FSI, allowing evaluation of two-way FSI effects on the dynamic characteristics of a tank with flexible and rigid walls. The accuracy of the coupling FVM/FEM method was confirmed through comparison with previous studies and design codes, focusing on natural frequency, liquid sloshing, and hydrodynamic pressure measurements.

Results indicated that the frequencies of flexible tank walls differ from those of rigid walls, particularly in terms of the hydrodynamic pressure exerted by liquid motion. The peak hydrodynamic pressure on thick-walled tanks, when considering FSI, was 38.2 kPa, a minimal deviation of 0.2% from the ACI standards (38.12 kPa) and 5.47% from EC8 (36.11 kPa). The analysis further revealed that incorporating two-way interaction in thin-walled tanks increases the deviation from ACI and EC8 standards to 12.2% and 16.8%, respectively.

A “threshold value” was identified to differentiate between flexible and rigid tanks; beyond this threshold, thicker tanks experience lower hydrodynamic pressure, whereas thinner tanks show the opposite effect. The study confirms a strong correlation between the numerical results and the analytical, published, and experimental data.