Coalescence-Induced Swift Jumping of Nanodroplets on Curved Surfaces

He, Xukun; Zhao, Lei; Cheng, Jiangtao

doi:10.1021/acs.langmuir.9b01300

Cited by 21 publications

(13 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Wang et al reported a millimetric triangular prism macrotexture and achieved a maximum droplet jumping velocity V j * = 0.53, with an energy conversion efficiency η ≈ 22.49% . In addition, rectangular ridge structures, curved surfaces, hydrophobic fibers, strings, and V-shaped structures , have been used to obtain a higher jumping velocity and break the velocity limit. Furthermore, Yuan et al used the impact between the liquid bridge and the bottom, flank side of the L-shaped macrotexture.…”

Section: Introductionmentioning

confidence: 99%

Enhancement and Guidance of Coalescence-Induced Jumping of Droplets on Superhydrophobic Surfaces with a U-Groove

Liu

Zhao

Zheng

et al. 2021

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Coalescence-induced droplet jumping has received considerable attention owing to its potential to enhance performance in various applications. However, the energy conversion efficiency of droplet coalescence jumping is very low and the jumping direction is uncontrollable, which vastly limits the application of droplet coalescence jumping. In this work, we used superhydrophobic surfaces with a U-groove to experimentally achieve a high dimensionless jumping velocity V j * ≈ 0.70, with an energy conversion efficiency η ≈ 43%, about a 900% increase in energy conversion efficiency compared to droplet coalescence jumping on flat superhydrophobic surfaces. Numerical simulation and experimental data indicated that a higher jumping velocity arises from the redirection of in-plane velocity vectors to out-of-plane velocity vectors, which is a joint effect resulting from the redirection of velocity vectors in the coalescence direction and the redirection of velocity vectors of the liquid bridge by limiting maximum deformation of the liquid bridge. Furthermore, the jumping direction of merged droplets could be easily controlled ranging from 17 to 90°by adjusting the opening direction of the U-groove, with a jumping velocity V j * ≥ 0.70. When the opening direction is 60°, the jumping direction shows a deviation as low as 17°from the horizontal surface with a jumping velocity V j * ≈ 0.73 and corresponding energy conversion efficiency η ≈ 46%. This work not only improves jumping velocity and energy conversion efficiency but also demonstrates the effect of the U-groove on coalescence dynamics and demonstrates a method to further control the droplet jumping direction for enhanced performance in applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Enhancement and Guidance of Coalescence-Induced Jumping of Droplets on Superhydrophobic Surfaces with a U-Groove

Liu

Zhao

Zheng

et al. 2021

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…Furthermore, Xie et al patterned a single nanometric rectangular ridge to enhance nanodroplet jumping velocity; molecular dynamics simulations showed that the maximum jumping velocity was 1.81 times higher than the nanoscale velocity limit . Besides that, curved surface and hydrophobic fibers ,, have also been used to successfully enhance the jumping velocity of microdroplets.…”

Section: Introductionmentioning

confidence: 99%

Self-Enhancement of Coalescence-Induced Droplet Jumping on Superhydrophobic Surfaces with an Asymmetric V-Groove

Zhao

Zhang

et al. 2020

Langmuir

View full text Add to dashboard Cite

Coalescence-induced droplet jumping on superhydrophobic surfaces have recently received significant attention owing to their potential in a variety of applications. Previous studies demonstrated that the self-jumping process is inherently inefficient, with an energy conversion efficiency η ≤ 6% and dimensionless jumping velocity V j* ≤ 0.23. To realize a quick removal of droplets, increasing effort has been devoted to breaking the jumping velocity limit and inducing droplets sweeping. In this work, we used superhydrophobic surfaces with an asymmetric V-groove to experimentally achieve an enhanced coalescence-induced jumping velocity V j* ≈ 0.61, i.e., more than 700% increase in energy conversion efficiency compared with droplets jumping on flat superhydrophobic surfaces, which is the highest efficiency reported thus far. Moreover, the enhanced jumping direction shows a deviation as high as 60° from the substrate normal. The induced in-plane motion is conducive to remove a considerable number of droplets along the sweeping path and significantly increase the speed of droplet removal. Numerical simulation indicated that the jumping enhancement is a joint effect resulting from the impact of the liquid bridge on the corner of the V-groove and the suppression of droplet expansion by the sidewall of the V-groove. The transient variation of the droplet velocity and the driving force of the coalescing droplets on a surface with and without the asymmetric V-groove were revealed and discussed. Furthermore, effects of groove angle, droplet pair positions, and size mismatches on the jumping velocity and direction have been studied. The novel mechanism of simultaneously increasing the coalescence-induced droplet jumping velocity and changing the jumping direction can be further studied to enhance the efficiency of various applications.

show abstract

“…Previous studies have shown that the jumping efficiency of micron- and millimeter-scale droplets can be significantly tuned by constructing ridges, microgrooves, , and egg tray-like structures on superhydrophobic surfaces. The research on nanoscale droplet confluence by molecular dynamics simulations also shows that the jumping velocity can be significantly increased by constructing individual grooves, ridges, or more hydrophobic strips on the superhydrophobic surface with dimensions comparable to the radius of the coalescing droplets. , The above study analyzed the mechanism of enhancing droplet jumping velocity by geometric structures and confirmed that macroscopic structures can effectively enhance the efficiency of coalescence-induced droplet jumping, but this is still a long way from achieving large-scale efficient droplet jumping. On the one hand, previous studies have focused on the jumping of individual droplets, − usually studying only the effect of individual macroscopic structures on droplet jumping, which cannot be directly applied to large scales.…”

Section: Introductionmentioning

confidence: 84%

Coalescence-Induced Droplet Jumping on Honeycomb Bionic Superhydrophobic Surfaces

Gao

Yang

et al. 2022

Langmuir

View full text Add to dashboard Cite

Condensation-induced jumping of droplets on superhydrophobic surfaces has received extensive attention because of its great potential for applications in areas such as condensation enhancement and self-cleaning. However, the jumping efficiency of droplets on flat superhydrophobic surfaces is very low, and there is no reliable means of achieving efficient droplet jumping on large scales, which greatly limits its application. To this end, we developed a class of honeycomb bionic superhydrophobic surfaces (HBSS) that enable reliable and efficient droplet jumping on a large scale for the first time and performed experimental and simulation studies on droplet condensation and jumping on this kind of surface. Condensation experiments show that condensate droplets on HBSS can be effectively positioned under the influence of gravity and the uniformity of the droplet diameter is ensured, laying the foundation for achieving efficient jumping. The shape and geometric parameters of HBSS have a significant impact on the droplet jumping efficiency, and the maximum dimensionless jumping velocity of droplet jumping was experimentally measured to be 0.747, corresponding to an efficiency of about 45.25%. Combining with the results of simulation calculations, we found that the surface structure of HBSS can promote more of the excess surface energy to net upward kinetic energy along an extremely efficient and simple pathway (direct conversion), thus achieving an energy conversion efficiency of over 45%.

show abstract

Coalescence-Induced Swift Jumping of Nanodroplets on Curved Surfaces

Cited by 21 publications

References 39 publications

Enhancement and Guidance of Coalescence-Induced Jumping of Droplets on Superhydrophobic Surfaces with a U-Groove

Enhancement and Guidance of Coalescence-Induced Jumping of Droplets on Superhydrophobic Surfaces with a U-Groove

Self-Enhancement of Coalescence-Induced Droplet Jumping on Superhydrophobic Surfaces with an Asymmetric V-Groove

Coalescence-Induced Droplet Jumping on Honeycomb Bionic Superhydrophobic Surfaces

Contact Info

Product

Resources

About