ABSTRACT:

This paper describes a simple, fast and effective numerical tool that can be employed to predict the onset of liquid sloshing in tanks and assess the severity of the hydrodynamic pressures applied on the tank walls. A potential flow model with linear boundary conditions was chosen to give an initial screening tool that provides reasonable accuracy and computational speed. The liquid in the tank is assumed incompressible and inviscid, and the flow is assumed irrotational. The flow can be then described by a velocity potential Ф(t, x, y, z) which is governed by the Laplace equation. The flow problem can be formulated as an initial-boundary value problem. At each time step, the boundary value problem for the velocity potential is solved using a desingularized boundary integral method. A timestepping approach is used, in which the kinematic and dynamic boundary conditions on the liquid free surface are integrated in time to update the surface elevation and the velocity potential for the next time instant. Three-dimensional problems are studied.

INTRODUCTION

Sloshing of liquid cargo in a partially-filled tank can cause large pressures on the tank walls. In the case of wave periods close to the liquid natural periods, sloshing can become violent and may lead to structural failures. The underlying physics of the problem are very complex and not fully understood. A recent paper by Yung et al (2010) describes all the relevant parameters of the problem as well as the learning from an extensive model testing campaign. Advanced CFD methods (such as volume of fluid methods, level-set methods and SPH methods) have been proposed and developed in recent years for simulating liquid sloshing and providing better prediction of the phenomena (Yang and Lohner 2005, Lohner et al 2007, Pakozdi and Graczyk 2009, and Cao et al 2010).

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