The interactive dynamic behaviour of an air-liquid-elastic spherical tank system

The dynamic behaviour of an air-liquid-elastic spherical tank interaction system is investigated. The tank is fully filled with a non-viscous liquid and air and supported at four equally spaced positions around the outer shell. The governing equations describing this system are presented. A mixed displacement–pressure finite element method is developed adopting the dynamic pressure in the liquid / air and the displacement in the elastic solid as variables to initiate a numerical model incorporating a substructure-subdomain approach. Numerical simulations are presented based on a developed computer program FSIAP. The natural sloshing frequencies and the corresponding vibration modes of the coupled system are derived. To reveal different interactive mechanisms, four cases are investigated. Namely, 1) liquid sloshing in a rigid tank; 2) air-liquid interactions in a rigid tank; 3) liquid-elastic tank interactions; 4) three phase air-liquid-tank interactions. The numerical results obtained demonstrate the complex coupled behaviour of the system. This study provides information for the design of liquid / gas filled tanks in which structure sloshing behaviour is of interest