Modeling dynamic interaction between an emerging water droplet and the sidewall of a trapezoidal channel

Water droplet–sidewall interactions at the corner of the two walls of different surface energies are a significant problem from a fundamental perspective. Such conditions are encountered in many diverse applications. In proton exchange membrane fuel cells (PEMFCs), removal of water droplets emerging from the base of a horizontal gas diffusion layer (GDL) into the gas channel has been a major issue from water management perspective. Recent studies have provided valuable understanding on the water droplet behavior near the GDL/sidewall corner. Two distinct behaviors of filling and non-filling of the gas channel corners were observed by the previous investigators when the emerging droplet interacted with the sidewall. However, authors’ group also observed a new condition, droplet jumping to the sidewall under specific combinations of the corner angle, and the base and sidewall contact angles. The focus of the present work is to gain a fundamental understanding of the droplet–sidewall interactions in terms of the droplet jumping, corner filling, and non-filling behaviors without airflow. This work is complemented with an experimental study by varying the location of the droplet emergence, the corner angle, and the surface energies of the walls.