A Numerical Investigation of the Dynamic Wetting Transition on a Moving Substrate

The dynamic wetting transition of an interface on a partially wetting substrate is numerically investigated using a diffuse-interface method. Both advancing and receding contact lines are considered. As the driving speed of the substrate exceeds a threshold, the contact line keeps moving with the plate and cannot remain stable. For the receding case, the onset of wetting transition is found to agree with previous lubrication theory, and the transition can be delayed by changing boundary conditions such that the macroscopic meniscus can maintain a pressure difference. For the transition of an advancing contact line, the apparent contact angle remains finite, and the critical speed decreases with the contact angle, which is opposite to the receding case.