Mechanism Study on Motion of the Droplet on a Slanted Smooth Surface under Horizontal Airflow

Aiming at the process of the droplet motion on a slanted smooth substrate surface driven by horizontal airflow velocity, a numerical simulation model of droplet on a slanted smooth substrate surface was established based on an arbitrary Lagrange-Euler method. Combined with the numerical simulation and experimental analysis, the motion state of the droplet and the distribution characteristics of the airflow velocity in the direction perpendicular to the slanted smooth surface near the bottom contact line at the lower end of the droplet were studied at different horizontal airflow velocity. It is considered that there were four regions in the airflow velocities: the low-velocity non-linear region close to the wall, the linear zone, non-linear transition zone and high-speed linear zone, of which h(1) = 0.25 mm, h(2) = 0.9 mm, h(3) = 1.4 mm. The results show that the droplet moved in a spreading-shrinking manner on the slanted smooth substrate surface under the action of gravity and wind force. The experimental results verify the correctness of the spreading-shrinking movement of the droplet on a slanted smooth surface. Based on the numerical simulation and experimental analysis, it is considered that the instability of liquid-gas free interface affects the movement of the three-phase contact line, the deformation of the droplet on the windward side was large and on the leeward side was small.