Droplet moving on frosted glass

The surface of the frosted glass is very rough. This roughness offers numerous pinning sites for any sessile droplet. In the present case, the angle of contact of a water droplet is about 50°. The advancing angle is rather large (about 70°) and contrasts with the receding angle that is quite zero. This strong hysteresis has a direct consequence on the motion of a droplet when the plate is inclined. The droplet leaves a trace after its passage. The dynamic of the droplet going down the plane is studied and the microflows in the trace are described. Finally, the behavior of oil droplets is compared. As the oil wets the glass, the motion of the sliding droplet superposes to the diffusion process of the oil in the crevices of the frosted surface.