Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-cam...Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.展开更多
Vibration is a common strategy for aquatic organisms to achieve their life activities,especially at the air-water interface.For the locomotion of small creatures,the organs with plate features are often used on water ...Vibration is a common strategy for aquatic organisms to achieve their life activities,especially at the air-water interface.For the locomotion of small creatures,the organs with plate features are often used on water surfaces,which inspires relevant studies about using thin plates for robot propulsions.However,the influence of the general deformations of thin plates on the generated flow fields has not been considered.Here,a comprehensive investigation is conducted about the flow fields that arose by vibrations of thin plates and the potential as locomotion strategies are explored.It is discovered that as thin plates are subjected to vibration excitations on the water surface,the produced flow fields are mainly determined by the vibration shapes,and the influence rules of plate deformations on the flow fields are identified.The main factors producing asymmetric flow fields are analyzed to realize the morphology control of the flow fields.Then,to determine effective locomotion strategies on the water surface,the flow fields stimulated by integrated vibration exciters are explored,and 2 water surface robots are developed consequentially.which exhibit superior motion performance.This work reveals the basic rules of the vibration-induced-flow mechanism by thin plates and establishes new locomotion strategies for aquatic robots.展开更多
基金supported by the National Key R&D Program of China(grant nos.2022YFF0503500 and 2022YFA1203200)the Guangdong Basic and Applied Basic Research Foundation(grant no.2023A1515011784)+2 种基金the National Natural Science Foundation of China(grant no.12032019)the Strategic Priority Research Program of Chinese Academy of Sciences(grant nos.XDB0620101 and XDB0620103)the Youth Innovation Promotion Association,Chinese Academy of Sciences(no.2020020).
文摘Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.
基金supported by the National Natural Science Foundation of China(no.52225501)the State Key Laboratory of Robotics and System(HIT)(no.SKLRS-2022-ZM-01).
文摘Vibration is a common strategy for aquatic organisms to achieve their life activities,especially at the air-water interface.For the locomotion of small creatures,the organs with plate features are often used on water surfaces,which inspires relevant studies about using thin plates for robot propulsions.However,the influence of the general deformations of thin plates on the generated flow fields has not been considered.Here,a comprehensive investigation is conducted about the flow fields that arose by vibrations of thin plates and the potential as locomotion strategies are explored.It is discovered that as thin plates are subjected to vibration excitations on the water surface,the produced flow fields are mainly determined by the vibration shapes,and the influence rules of plate deformations on the flow fields are identified.The main factors producing asymmetric flow fields are analyzed to realize the morphology control of the flow fields.Then,to determine effective locomotion strategies on the water surface,the flow fields stimulated by integrated vibration exciters are explored,and 2 water surface robots are developed consequentially.which exhibit superior motion performance.This work reveals the basic rules of the vibration-induced-flow mechanism by thin plates and establishes new locomotion strategies for aquatic robots.
