Droplet impact on solid surfaces is widely involved in diverse applications such as spray cooling,self-cleaning,and hydrovoltaic technology.Maximum solid‒liquid contact area yielded by droplet spreading is one key par...Droplet impact on solid surfaces is widely involved in diverse applications such as spray cooling,self-cleaning,and hydrovoltaic technology.Maximum solid‒liquid contact area yielded by droplet spreading is one key parameter determining energy conversion between droplets and surfaces.However,for the maximum deformation of impact droplets,the contact length and droplet width are usually mixed indiscriminately,resulting in unignored prediction errors in the maximum contact area.Herein,we investigate and highlight the difference between the maximum contact length and maximum droplet width.The maximum droplet width is never smaller than the maximum contact length,and the difference appears once the contact angle exceeds 90◦(which becomes more significant on superhydrophobic surfaces),regardless of impact velocities,liquid viscosities,and system scales(from macroscale to nanoscale).Atheoretical model analyzing the structure of the spreading rim is proposed to demonstrate and quantitatively predict the above difference,agreeingwell with experimental results.Based on molecular dynamics simulations,the theoretical analysis is further extended to the scenario of nanodroplets impacting on solid surfaces.Reconsideration on themaximum deformation of impact droplets underscores the often-overlooked yet significant difference between maximum values of contact length and droplet width,which is crucial for applications involving droplet‒interface interactions.展开更多
基金China Postdoctoral Science Foundation,Grant/Award Numbers:2023TQ0210,GZB20230403Beijing Natural Science Foundation,Grant/Award Number:3242018National Natural Science Foundation of China,Grant/Award Number:52406104。
文摘Droplet impact on solid surfaces is widely involved in diverse applications such as spray cooling,self-cleaning,and hydrovoltaic technology.Maximum solid‒liquid contact area yielded by droplet spreading is one key parameter determining energy conversion between droplets and surfaces.However,for the maximum deformation of impact droplets,the contact length and droplet width are usually mixed indiscriminately,resulting in unignored prediction errors in the maximum contact area.Herein,we investigate and highlight the difference between the maximum contact length and maximum droplet width.The maximum droplet width is never smaller than the maximum contact length,and the difference appears once the contact angle exceeds 90◦(which becomes more significant on superhydrophobic surfaces),regardless of impact velocities,liquid viscosities,and system scales(from macroscale to nanoscale).Atheoretical model analyzing the structure of the spreading rim is proposed to demonstrate and quantitatively predict the above difference,agreeingwell with experimental results.Based on molecular dynamics simulations,the theoretical analysis is further extended to the scenario of nanodroplets impacting on solid surfaces.Reconsideration on themaximum deformation of impact droplets underscores the often-overlooked yet significant difference between maximum values of contact length and droplet width,which is crucial for applications involving droplet‒interface interactions.
