SLOSHING IN HALF-FULL SPHERE UNDER TRANSVERSE EXCITATION

Abstract

Sloshing is a common phenomenon found in partially filled liquid containers caused due to external excitation. It is observed in Elevated Water Tank, Fuel tank of a vehicle, Liquefied Natural Gas (LNG) container, Ships, etc. Sloshing induces sig-nificant amount of additional pressure on the wall of container which is already subjected to hydrostatic pressure. The problem is quite acute for a LNG container on a floating barge as the external excitation remains in action for a long period of time. A significant amount of research has been done on sloshing giving rise to a variety of methods. Analytical, experimental and as well as numerical solution for differ-ent types of containers are available. Analytical methods are available for several container types including spherical one. Spherical containers are used to store and transport LNG. In the present study an analytical method for a spherical con-tainer has been simplified for use in practical problems. The analytical method is based on series representation of velocity potential function in terms of associated legendre function. It has been verified in terms of the natural frequency found in other literatures. It has been found to be quite efficient even with few number of terms. The ana-lytical expressions has been applied for the case of a spherical LNG container on a floating barge to observe the hydrodynamic pressure variation under different. loading conditions. For this work, several programs have been developed. Con-tainers of different radius have been analysed for external excitations caused due to different wave velocities along the barge, and different wave heights. The an-alytical expressions provided good result which is comparable with other existing methods. It has been found that for floating barge, container of smaller radius experiences lesser amount of sloshing.