A dynamic meshing technique for analysis of nonlinear sloshing in liquid tanks

Abstract

Fluid sloshing in tanks is a form of liquid surface motion that occurs when an external excitation is applied to a partially filled container. It is an important phenomenon, as the ensuing hydrodynamic pressure on the wall of the tank may cause the structure to fatigue and thus may destroy the tank. This work aimed to study the effects of baffles at different positions in a tank subject to sudden acceleration as part of countering such damage. An ANSYS Fluent model for three different fill levels of tank was used for transient analysis in 2D, while a multiphase model was used to track the free surface of the liquid based on Volume of Fluid (VOF) and a dynamic meshing technique was used to simulate the excitation sources via a User Defined Function (UDF) code in the C++ environment. The numerical simulation showed that the baffles significantly reduced the fluid flow in the partially filled tank, consequently influencing the sloshing pressure acting on the wall of the tank; this reduced the magnitude of sloshing in the tank by 30% and lowered the impact pressure by 21% at maximum, an important design outcome. As the level of fill increased, the pressure also increased, though the baffles limited this variation, leading to low sloshing. In general, the value of pressure inside the tank decreased with increases in the value of excitation frequency in all cases. Validation of the results is conducted by comparing the simulation data with experimental results, and good agreement between them was found, confirming the effectiveness and accuracy of the applied method.