Abstract

Understanding the mechanisms of liquid movement through fracture intersections is important for prediction of fluid flow and solute transport in unsaturated fractured media. Here we present a quasi-static model to predict the dynamic splitting behavior of liquid slugs at a T-junction, as a simplified representation of a fracture intersection and consisting of a main channel and a branch channel. The proposed model is validated against carefully controlled visualization experiments. We find that there exists a critical initial slug length at which the splitting behavior shifts from flow dominated by the main channel to that dominated by the branch. The influence of key parameters, including the inclination angle of the junction, the channel widths, and the dynamic contact angles, on the splitting dynamics is systematically investigated. We show that the splitting ratio depends non-monotonically on the relative width of the branch channel to the main channel. Furthermore, it is demonstrated that the dynamic contact angles have a profound impact on the splitting ratios and meniscus velocities. It is shown that taking velocity-dependent contact angle into account is essential to predict the meniscus velocities and the dynamic flow process.