Numerical study of the damped oscillation of liquid column in U-tube with particle method

The damped oscillation process of the liquid column in a U-tube is simulated and studied using the moving particle semi-implicit (MPS) method. The oscillation process is well reproduced and the effect of liquid properties as the density and viscosity is investigated, as well as the size effect of the U-tube. As key parameters, the amplitude and the period of the oscillation are calculated and analyzed when the flow conditions are changed. The results show that the amplitude and the average period of the oscillation process decrease when the liquid viscosity increases, and that the liquid density has a minor influence on the damping process. A critical finding for the size effect is that the oscillation process almost changes linearly with the size of the U-tube larger than the critical point, but nonlinearly when the size is scaled down. Larger viscosity results in shorter equilibrium time and viscosity plays a more important role in damping, especially for a smaller size of the U-tube. These versatile numerical protocols can present useful qualitative suggestions on the applications of a U-tube in many industrial fields.