Drop Impact on Two-Tier Monostable Superrepellent Surfaces

Shi, Songlin; Lv, Cunjing; Zheng, Quanshui

doi:10.1021/acsami.9b14880

Cited by 25 publications

(15 citation statements)

References 70 publications

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“…As shown in Figure b, τ st * and τ rt * are both constants regardless of We n and α: τ st * ≈ 0.64 and τ rt * ≈ 1.17. Droplet spreading is dominated by the normal inertial force, and the spreading time is proportional to τ 0 . , In addition, on inclined surfaces, the inertial force is much larger than the tangential component of droplet gravity and α also has little effect on the spreading time; hence, τ st * ≈ const. For the tangential retraction, τ rt depends on the maximum tangential contact length and the tangential retraction velocity.…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

“…Droplet spreading is dominated by the normal inertial force, and the spreading time is proportional to τ 0 . 50,51 In addition, on inclined surfaces, the inertial force is much larger than the tangential component of droplet gravity and α also has little effect on the spreading time; hence, τ st * ≈ const.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces

Chu

Lin

et al. 2022

Langmuir

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“…As shown in Figure 6d, experiment results obey the model based relationship V Ret,R = 1.349(γ/ ρh ) 0.5 (dotted line) and V Ret,W = 0.523(γ/ ρh ) 0.5 (solid line). Since the instability of wetting state transition for impact at low We N , [ 46 ] some of droplets cannot be detected the V Ret,W .…”

Section: Resultsmentioning

confidence: 99%

Air Cushion Storing Energy Promoting Droplets Retraction and Flow on Engineering Porous Bionic Lotus Surfaces

Zhu

Luo

et al. 2022

Adv Materials Inter

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Porous bionic self‐cleaning surfaces with low contact time of droplets show good potentials in anti‐icing, drag reduction, antifouling, etc. However, the reason of asymmetric and fast retraction on inclined surfaces after droplet impact is not clear. Here, it is reported that the fast retraction is mainly ascribed to the “air cushion” in porous surface acting as “energy reservoir” that stores excess kinetic energy of droplet during spread and returns it back promoting droplets retraction with contact time 20–40% off. Besides, the pinning effect and wetting state transition result in the asymmetric morphology evolution and suddenly stretch along tangential. A physical model of droplet asymmetric retraction including the influence of dynamic wetting angle fDCA, pinning effect fPin, and air cushion fAir is innovatively proposed to describe droplet morphologic evolution. The fundamental understanding of droplets impact dynamic on inclined surfaces is beneficial for engineering applications of extremely wettable surfaces.

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“…22m). As discussed in Section 3.1, liquid droplet/jet impacting can trigger thermodynamic instability of super liquidrepellent surfaces via cushions removal induced Cassie-Baxter to Wenzel transition, 299,[302][303][304][305][306] as well as the drainage of the infusedliquid due to commonly observed meniscus and cloaking. 341 It should be emphasized that the interaction between dynamic liquids (including droplet, jet, and flow) and liquid-repellent surfaces could have a negative effect on their surface textures and/or infused-liquid due to the generated shear force, which sometimes leads to the loss of liquid repellence.…”

Section: Mechanical Durabilitymentioning

confidence: 99%