Dynamics of micrometer-sized droplet impact on vertical walls with different surface roughness

Micrometer-sized droplets impacting on a vertical wall with different surface roughness were numerically studied, with both the single droplet impact and the multiple droplets impact being investigated. The phenomena of the multiple droplets impact were simplified to two droplets successive impact and simultaneous impact. The simulation model was based on the CLSVOF method with the dynamic contact angle considered. The morphology of the single droplet and the droplet pair were compared in the transverse and longitudinal directions. It was found that the surface roughness had a greater effect on the transverse direction, and the rougher the surface, the less the deformation. The depth of the droplets infiltrated into the rough peak was then analyzed. The result indicated that the infiltration depth increased with the impacting velocity, and the interactions between the two successive droplets could affect their forward infiltration into the wall.