A new insight into the stability of static and dynamic liquid bridges in smooth-walled horizontal fractures

The stability of liquid bridges formed between two solid substances plays an important role in many industrial applications, including oil–water separation, granular materials, offset printing and oil recovery from fractured reservoirs. Despite numerous studies, fundamental understanding of how slipping and pining regimes of contact angle, may affect the stability of stretching liquid bridges formed between two solid substances is not discussed in the available literature. In this study, the impact of slipping and pining regimes of contact angle on the stability of the dynamic liquid bridge was investigated. To do that, a Computational Fluid Dynamic (CFD) model was developed and used to analyze liquid bridge stability/evolution in a smooth horizontal fracture for static and dynamic conditions. The models' validities were checked by comparing the models' results with the experimental data. In the static modeling part, a new expression for predicting the rupture distance of liquid bridge was proposed which could be applied for a wide range of liquid bridge volume, contact angle, and Bond number. The power of the liquid bridge volume in the expression depends on both the liquid bridge volume and surface wettability. In the dynamic modeling part, as an interesting result, it was observed that the variations of the rupture distance with Weber, Capillary, and Bond numbers strongly depend on the regimes of contact angle, and the rupture distance for the slipping regime is greater than that of the pinning regime by a factor of 1.02–1.32 depending on liquid bridge volume and surface wettability. The results also showed that the rupture distance approaches asymptotic values for the Bond, Weber, and Capillary numbers equal or less than 10-2, 10-4, and 10-5, respectively. The results of this study contribute to better understanding of how regimes of contact angle would affect liquid bridge stability in smooth horizontal fractures and could improve our understanding of interfacial flow in fractured rocks.