(524g) Computational Study of Moving Triple Lines

Wetting of chemically heterogeneous surfaces is modeled using phase field theory. This model studies the one-dimensional kinetic processes involved in wetting a substrate similar to a Wilhelmy technique. The experimental technique provides a complete validation of the phase field theory due to its capability to capture the triple line kinetics in addition to measuring the contact angles during the advancing and receding processes. In the current model, contact angle hysteresis is incorporated by a modified kinetic parameter.

A chemically heterogeneous surface is said to be composed of a predetermined arrangement of two materials. The novelty in the current approach lies in the fact that each of the component materials is constitutively allowed to exhibit hysteresis. We investigate the local shape of the triple line which is known to play an important role in determining the macroscopic contact angle due to its ability to be pinned at various defect locations on real surfaces. We also demonstrate that the shape of the advancing and receding triple line is sensitive to the specific arrangement of the two materials. The work provides insight into the fabrication of chemically heterogeneous surfaces for desired wetting applications.