Behavior of a liquid drop in a rounded corner: Different contact angles

The Concus-Finn condition, based on the local microscopic contact angle, can be used to predict discontinuous behavior of a liquid drop in an ideally sharp corner. However, since ideally sharp corners do not exist in reality, it is important to understand the effect of rounded corners on the behavior of liquid drops. In this paper, we use theoretical calculations to study the behavior of two-dimensional liquid drops in rounded corners, including the case in which the contact angles on the two sides of the corner may differ. A new discontinuous behavior was discovered in our study, which is different from the case in sharp corners. Comparing the situation in sharp corners, our study shows that the behavior of a drop in a rounded corner depends on the dimensionless volume of the drop, in addition to its dependence on the opening angle and contact angles that is covered by the Concus-Finn condition. We also use energy-minimization approach to successfully explain why this discontinuous behavior occurs in rounded corners.