Droplet impact dynamics on single-pillar superhydrophobic surfaces

Ding, Siyu; Hu, Zhifeng; Dai, Liyu; Zhang, Xuan; Wu, Xiaomin

doi:10.1063/5.0066366

Cited by 43 publications

(11 citation statements)

References 49 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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“…To ensure that the droplets did not break up, the tip-to-surface distance and droplet size were rationally selected such that the Weber number (We) is sufficiently small (We ≈ 2.6). 42 The bouncing time is quantified as the total time that the droplet spends bouncing on the surface prior to pinning. We used the droplet-bouncing method due to its advantages in comparison to static or dynamic contact angle and droplet roll-off measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Deionized water droplets (D140 Culligan deionizer system) having 10 ± 0.002 μL volumes were individually released from a capillary tip (CLS4853-400EA, Corning) with the tip-to-surface distance maintained at 7 ± 0.1 mm (Section S3 in the Supporting Information). To ensure that the droplets did not break up, the tip-to-surface distance and droplet size were rationally selected such that the Weber number (We) is sufficiently small (We ≈ 2.6) . The bouncing time is quantified as the total time that the droplet spends bouncing on the surface prior to pinning.…”

Section: Resultsmentioning

confidence: 99%

Tunable and Robust Nanostructuring for Multifunctional Metal Additively Manufactured Interfaces

Rabbi

Khodakarami

et al. 2022

Nano Lett.

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Novel processing phenomena coupled with various alloying materials used in metal additive manufacturing (AM) have opened opportunities for the development of previously unexplored micro-/nanostructures. A rationally devised structure nanofabrication strategy of AM surfaces that can tailor the interface morphology and chemistry has the potential for many applications. Here, through an understanding of grain formation mechanisms during AM, we develop a facile method for tuning micro-/nanostructures of one of the most used AM alloys and rationally optimize the morphology for applications requiring low surface adhesion. We demonstrate that optimized AM structures reduce the adhesion of impaling water droplets and significantly delay icing time. The structure can also be altered and optimized for antiflooding jumping-droplet condensation that exhibits significant enhancement in heat transfer performance in comparison to nanostructures formed on conventional Al alloys. In addition to demonstrating the potential of functionalized AM surfaces, this work also provides guidelines for surface-structuring optimization applicable to other AM metals.

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“…They found that the contact time of droplets impacting on an SHS decorated with a macroscopic ridge was reduced by about 37% because of the asymmetric spreading and retraction. Since then, SHSs with various submillimetric or millimetric macrostructures have been designed and fabricated (such as cylindrical/semicylindrical ridges, − trigonal ridges, − cuboid ridges, , cylindrical/conical pillars, − suspending cylinders, , and point-like protrusions), and the contact time on most structural surfaces is reduced by about 30–50% compared to that on horizontal flat SHSs. Recently, macrostructures (such as a dimple and circular grooves) have been further used to navigate the transport of droplets.…”

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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Droplet impact dynamics on single-pillar superhydrophobic surfaces

Cited by 43 publications

References 49 publications

Dynamics of droplet impacting on a cone

Dynamics of droplet impacting on a cone

Tunable and Robust Nanostructuring for Multifunctional Metal Additively Manufactured Interfaces

Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces

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