Numerical study of coupled slosh modes in a 3D vessel subjected to multi-directional excitations

Abstract

Present study explores liquid sloshing in a three-dimensional (3D) rectangular tank subjected to surge and coupled surge, sway and heave excitations. A number of applications of practical interest in nuclear systems such as, spent fuel storage tanks, fast reactor vessels, pool type coolant etc will be benefited from such analysis. Effect of harmonic excitation is investigated emphasizing finite liquid depth when the internal resonance condition 1:1 is satisfied between the natural frequencies of dominant modes (1,0), (0,1) and (0,2). The numerical model was validated against available in–house experimental shake table studies. Temporal snapshots of velocity magnitudes and free surface time history at different locations are presented when the tank is excited under two different loading conditions. The amplification of diagonal slosh modes were observed under planar excitation. This analysis assumes significance, as the attendant hydrodynamic forces could eventually cause fatigue failure of the tank structure. Non-linear square-like, swirling and wave breaking features were observed, when the tank was subjected to earthquake excitation.