Pinch-off mechanism of a free elongated liquid ligament

The time-dependent relaxation dynamics of a moderately elongated liquid ligament has been studied numerically. The Navier-Stokes equations are solved using a finite-volume formulation with a two-step projection method on a fixed grid. The free surface of the liquid ligament is tracked by a coupled level set and volume-of-fluid (CLSVOF) method with the surface tension force determined by the continuum surface force (CSF) model. The relaxation process of a free elongated liquid ligament has been simulated and the numerical results are in agreement with findings reported in the literature. The end-pinching mechanism of the breakup process has been thoroughly examined. The determining factor for reopening of a pinching neck has been identified. The effects of several parameters on the relaxation mechanism have also been examined. It has been found that the initial end shape of the ligament and the Ohnesorge number play a vital role in the overall relaxation process.