Study on stretching liquid bridges with symmetric and asymmetric surface wettability

Abstract

The breakup process of stretching liquid bridges between plates is crucial for liquid transfer in printing technology. In the present study, the liquid bridges stretched by two parallel flat plates were simulated by using many-body dissipative particle dynamics, in which the competition between slip velocity of contact lines and thinning velocity of liquid bridges was focused on, and it shows that this competition plays a key role in determining the breakup behaviors of liquid bridges and the liquid transfer ratio between the two plates. The influences of surface wettability, plate stretching velocity, and liquid Oh number on the breakup process were discussed. The simulated results show that both poorer surface wettability and larger stretching velocity help to increase slip velocity and enable the liquid bridge to slip off the surfaces. For the case with hydrophilic surface and small plate stretching velocity, thinning velocity dominates the breakup process and the pinch-off occurs approximately at the middle part of the liquid bridge. For cases with asymmetric surface wettability, the liquid transfer ratio depends only on the asymmetry of surface wettability for smaller plate stretching velocity and larger Oh number. However, this phenomenon no longer occurs if the stretching velocity is increasing, where slip of the contact line becomes important. The shift of minimal radius for liquid bridges with asymmetric stretching velocities is also investigated, and it was found that the shift moment is only related to the surface wettability, regardless of the plate stretching velocity. Moreover, it shows that the formation of satellite drops depends on the sequential order of the appearance of the liquid bridge slipping off the surface and the breakup of the filament. The present work provides some insight to better understand the rupture mechanism of stretching liquid bridges, and may help to improve printing technology.