Dynamic behavior of droplet impacting on a moving surface

The research specifically analyzes the characteristics of the impacting droplet and its behavior on the moving surface. The experimental results demonstrate that the droplet impact can be divided into two stages: spreading and stretching. The surface shear force is found to play a decisive role in the droplet's dynamic behaviors. Specifically, the surface shear force inhibits liquid fingers at the front edge of the liquid film during the spreading stage, but promotes the extension of liquid fingers at the trailing edge of the droplet during the stretching stage. The surface shear force has a significant influence on the longitudinal spreading factor of the droplet during the spreading stage. The transverse maximum spreading time decreases with the increase of shear weber number. The wake flow of the droplet is mainly divided into four types: wetting deposition, fracture separation, single finger, and multi-fingers. Additionally, the ratio of the horizontal maximum spreading factor to the longitudinal spreading factor in the same time is found to be positively correlated with the ratio of the two weber numbers. The research findings contribute to the fundamental understanding of droplet dynamics on moving surfaces and highlights the importance of considering surface shear force in understanding droplet dynamics and provides a basis for further research in this field.