Three-dimensional resonant sloshing in a cylindrical tank with a central pillar baffle

This study explores three-dimensional resonant sloshing characteristics in cylindrical tanks equipped with a pillar baffle of three different heights, using systematic experiments, potential flow analysis, and the asymptotic multimodal method. The results reveal that as the height of the pillar baffle increases, the system's natural frequency decreases and the viscous damping increases, although these changes are not significant. Notably, minimal-height baffles (d/h = 0.25, where d is the baffle height and h is the water depth) maintain surface wave patterns identical to the clean tank, exhibiting three characteristic regimes: stable planar waves, irregular chaotic waves, and stable swirling waves. However, a surface-proximate baffle (d/h = 0.5 and 0.75) demonstrates the novel multi-mode wave interactions that are not observed in conventional configurations. Further analysis reveals that taller baffles substantially reduce the operational frequency bandwidth of irregular and swirling motions, shifting their occurrence toward lower excitation frequencies while achieving amplitude suppression. To the best of the authors' knowledge, this is the first systematic experimental investigation of three-dimensional resonant sloshing waves in cylindrical tanks equipped with a pillar baffle. The findings of the present study provide precise experimental data for validating analytical and numerical models and offer valuable physical insights to guide future research in this field.