Study On The Effect Of Superhydrophobic Surface Microstructure On Droplet Impact Dynamics

Wettability is one of the important characteristics of solid materials,which characterizes the physical and chemical properties of materials.Generally,surfaces with steady-state contact angles greater than 150° are superhydrophobic.The impact of liquid droplets on superhydrophobic surfaces is general and widely used in self-cleaning,antiicing,anti-corroding,blood analyzing and water harvesting,and is affected by temperature,pressure,liquid surface tension and many other factors.In view of the current research status,this paper prepared the micro-structured superhydrophobic surfaces by modifying nanoparticles of low surface energy on micro-column substrates with different structural parameters.Then droplet impact experiments were conducted on these surfaces to investigate the effect of specific microstructures on droplet impact dynamics.The results show that when the droplets impacted on the micro-structured superhydrophobic surfaces,the microstructures of the surfaces will enlarge the adhesion between the liquid and the surfaces and the energy dissipation during the impact.On this basis,the study on the single bouncing process of droplets impinging the micro-structured superhydrophobic surfaces found that droplets impacted on different micro-structured surfaces would result in deposition,complete rebound and splash,while the microstructures of the surfaces would influence the critical velocities of complete rebound and splash.At the same time,the microstructures of the superhydrophobic surfaces can change the retraction processes during the dynamic processes of droplets impact,increase the adhesion energy and viscous dissipation,reduce the energy restitution coefficient,and increase the recoiling time of droplets.In addition,the key factor affecting the maximum spreading factor and spreading time of the droplet is the impact velocity,and the inertia force dominates the lateral spread process of the droplet on the solid surface.Finally,the multi-rebound processes of droplets impinging the microstructured superhydrophobic surfaces were investigated.The results show that at low weber number,the number of rebound after hitting the superhydrophobic surfaces increases with the increase of weber number,and when the weber number increases to a certain value,the number of rebound decreases with the increase of weber number.For the droplets impact processes under the same weber number,the microstructures of the superhydrophobic surfaces will cause the increase of energy dissipation during droplets impact,thus reducing the rebound times.