Dynamics Behavior of Droplet Impact on a Controllable Curved Micropillar Array Surface Induced by a Magnetic Field

Many fields would greatly benefit from the realization of the manipulation of droplet impact behavior by an asymmetric surface structure, such as self-cleaning, anti-icing, inkjet printing, etc. However, research on the prediction of the impact of the dynamics of small-volume droplets on the asymmetric superhydrophobic surface has been insufficient. In this study, a superhydrophobic curved micropillar array surface with control-lable bending angles induced by a magnetic field was prepared. The impact and rebound behaviors of the nanoliter droplets with diameters of 100-300 mu m were investigated. The experimental results showed the positive correlation between the threshold Weber number of the impact morphology transition of the droplet and the inclination angle of the micropillar. In addition, the restitution coefficient, which measures the degree of energy loss during the impact process, showed a nonmonotonic dependence on the Weber number. A critical velocity model of the impact morphology transition of the droplet on the curved micropillar array surface and a prediction model of the restitution coefficient of the droplet in different impact morphologies are suggested. Our findings will help in the design of a functional surface for manipulating the impact behavior of the droplet.

Automated summary

The manipulation of droplet impact behavior on an asymmetric surface structure has great potential in various fields. However, there is a lack of research in predicting the dynamics of small-volume droplets on asymmetric superhydrophobic surfaces. In this study, a curved micropillar array surface with control-lable bending angles was prepared and the impact and rebound behaviors of nanoliter droplets were investigated. Experimental results showed correlations between droplet impact morphology and micropillar inclination angle, as well as nonmonotonic dependence of the restitution coefficient on Weber number.