Contact time on inclined superhydrophobic surfaces decorated with parallel macro-ridges

Lin, Dian-Ji; Zhang, Ling-Zhe; Yi, Meng-Chao; Gao, Shu‐Rong; Yang, Yan‐Ru; Wang, Xiao‐Dong

doi:10.1016/j.colsurfa.2020.124924

Cited by 31 publications

(8 citation statements)

References 37 publications

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“…It was found that liquid possessed a faster retraction along the ridge than that on the flat surface, leading to a 37% reduction in contact time. 21 Following this work, studies focused on contact time reduction by asymmetric dynamics have been carried out, including the inclined surface, 22,23 curved surface, [24][25][26][27][28][29][30] surfaces with macro structures of different geometries, [31][32][33][34][35][36][37][38][39][40] moving surfaces, 41,42 and off-center impact. 43,44 Besides the aforementioned asymmetric approaches, symmetric bouncing by involving the droplet center to retraction with point-like structure to reduce contact time has also been proposed.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of droplet impacting on a cone

Luo

Chu

et al. 2021

Physics of Fluids

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Droplet rebound dynamics on superhydrophobic surfaces has attracted much attention due to its importance in numerous technical applications, such as anti-icing and fluid transportation. It has been demonstrated that changing the macro-structure of the superhydrophobic surface could result in significant change in droplet morphology and hydrodynamics. Here we conduct both experimental and numerical studies of droplet impacting on a cone, and identify three different dynamic phases by changing the impacting conditions, i.e., the Weber number and the cone angle. The spreading and retracting dynamics are studied for each phase. Particularly, it is found that in Phase 3, where the droplet leaves the surface as a ring, the contact time is reduced by 54% compared with that of a flat surface. A theoretical model based on energy analysis is developed to get the rebound point in Phase 3, which agrees well with the simulation result. Besides, the effect of Weber number and cone angle on the contact time is explored.Finally, the phase diagram of the three phases distribution with We and cone angle is given, which can provide guidance to related applications.

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Section: Introductionmentioning

confidence: 99%

Dynamics of droplet impacting on a cone

Luo

Chu

et al. 2021

Physics of Fluids

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“…Due to the coupling effect of the surface structure and the surface inclination, the droplet spreading and retraction show strong anisotropy, and the asymmetry of the droplet deformation is enhanced. As a result, various droplet rebound modes are formed, and the contact time presents a complex trend with impact parameters. − In addition, for inclined SHSs with pillars or grooves, the pinning of droplets at high We n may increase the contact time; , for inclined SHSs with parallel ridges, the splitting behaviors of droplets may affect the contact time . The hydrodynamics of droplet impact on inclined structural SHSs are more complicated, but they are rarely studied, and the quantitative relationship between contact time and impact parameters is absent.…”

Section: Introductionmentioning

confidence: 99%

Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces

Chu

Lin

et al. 2022

Langmuir

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Superhydrophobic surfaces decorated with macrostructures have attracted extensive attention due to their excellent performance of reducing the contact time of impacting droplets. In many practical applications, the surface is not perpendicular to the droplet impact direction, but the impacting dynamics in such scenarios still remain mysterious. Here, we experimentally investigate the dynamics of droplet impact on inclined ridged superhydrophobic surfaces and reveal the effect of We n (the normal Weber number) and α (the inclination angle) on the contact time τ. As We n increases, τ first decreases rapidly until a platform is reached; if We n continues to increase, τ further reduces to a lower platform, indicating a three-stage variation of τ in low, middle, and high We n regions. In the middle and high We n regions, the contact time is reduced by 30 and 50%, respectively, and is dominated by droplet spreading/retraction in the tangential and lateral directions, respectively. A quantitative analysis demonstrates that τ in the middle and high We n regions is independent of We n and α, while the range of middle and high We n regions is related to α. When α < 30°, increasing α narrows the middle We n region and enlarges the high We n region; when α ≥ 30°, the two We n regions remain unchanged. In addition, droplet sliding is hindered by the friction and is affected by the droplet morphology in the high We n region. Overall, the synergistic effect of the surface inclination and macrostructures effectively promotes the detachment of impacting droplets on superhydrophobic surfaces, which provides guidance for applications of superhydrophobic surfaces.

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“…The behavior in each group is highly dependent on the centerto-center spacing of the parallel microridges. 12 In addition, impacting fluid has an important role in the droplet behavior over the slanted surface. The low-viscosity liquid droplets can either be spread and deposited on the surface or rebounded with the low rebound heights.…”

Section: ■ Introductionmentioning

confidence: 99%

“…This is because of the dynamic response of the droplet, which can be categorized mainly into two groups including nonbreaking and breaking behaviors of the droplet. The behavior in each group is highly dependent on the center-to-center spacing of the parallel microridges . In addition, impacting fluid has an important role in the droplet behavior over the slanted surface.…”

Section: Introductionmentioning

confidence: 99%

Impacting Water Droplets Can Alleviate Dust from Slanted Hydrophobic Surfaces

et al. 2021

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Water droplet impacting on a slanted dusty hydrophobic surface is examined in relation to dust mitigation from surfaces. Impacting droplet characteristics including droplet spreading/retraction rates, slipping length, and rebound heights are analyzed via high-speed recording and a tracker program. The environmental dust characteristics in terms of size, shape, elemental composition, and surface free energy are evaluated by adopting the analytical methods. The findings reveal that the dynamic characteristics of the impacting droplet on the slanted hydrophobic surface are significantly influenced by the dust particles. The maximum droplet spreading over the dusty surface becomes smaller than that of the nondusty surface. The presence of the dust particles on the slanted hydrophobic surface increases energy dissipation, and the water droplet slipping length over the surface becomes less than that corresponding to the nondusty surface. Impacting droplet fluid infuses over the dust particle surface, which enables mitigation of dust from the surface to the droplet fluid. A dust-mitigated area on the slanted surface is larger than that corresponding to the horizontal surface; in which case, the area ratio becomes almost six-fold, which slightly reduces with increasing Weber number. The optical transmittance of the dust-mitigated surface by the impacting droplet remains high.

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Contact time on inclined superhydrophobic surfaces decorated with parallel macro-ridges

Cited by 31 publications

References 37 publications

Dynamics of droplet impacting on a cone

Dynamics of droplet impacting on a cone

Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces

Impacting Water Droplets Can Alleviate Dust from Slanted Hydrophobic Surfaces

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