Lateral motion of a droplet impacting on a wettability-patterned surface: numerical and theoretical studies

Zhang, Tongwei; Wu, Jie; Lin, Xingjian

doi:10.1039/d0sm01858a

Cited by 8 publications

(22 citation statements)

References 43 publications

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“…Zhao et al (2019) and Chu et al (2020) further investigated the effect of impact position on the lateral transport distance. Russo et al (2020) and Zhang, Wu & Lin (2021) also observed similar phenomena in numerical simulations, and the effect of multiple parameters on the droplet motion was systematically investigated. The dominating factor of droplet lateral motion is the presence of asymmetric forces, which are induced by a hydrophilic stripe arranged on one side of the impact point (Zhao et al 2019(Zhao et al , 2021.…”

Section: Introductionmentioning

confidence: 68%

Lateral motion of a solid with a heterogeneous wettability surface driven by impacting droplets

Zhang

Wu²,

Lin³

2022

J. Fluid Mech.

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When a droplet impacts a solid with a heterogeneous wettability surface, the generated asymmetric forces can manipulate the droplet, and its counterforces can also actuate the solid in theory. In this study, a water droplet impacting a movable hydrophobic substrate, which is decorated with a hydrophilic stripe and restrained by two linear dampers, is studied numerically. After preliminarily checking the effects of the solid mass and damping coefficient of linear dampers, the dynamic mechanisms of solid motion are explored by analysing the variations in the lateral force and instantaneous displacement distance of the solid. After that, the effects of the impact parameters on the solid lateral motion are mainly investigated, including the initial droplet diameter, impact velocity and offset distance between the impact point and hydrophilic stripe. On this basis, the reciprocating solid motion under successive droplet impacts is studied, and periodic motion with different amplitudes can be realized under appropriate impact conditions. The obtained results can shed some fresh insight into the potential applications of droplet–solid interactions, which are valuable for the collection and utilization of energy from natural environments.

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Section: Introductionmentioning

confidence: 68%

Lateral motion of a solid with a heterogeneous wettability surface driven by impacting droplets

Zhang

Wu²,

Lin³

2022

J. Fluid Mech.

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“…Regulating surface wettability has proven to be an effective method for precisely controlling the droplet dynamic behaviors 34 , 35 . For example, the gyrating and dancing of droplets are realized through heterogeneous surface wettability regulation 33 , and droplet directional bouncing and materials transportation 36 – 39 have been achieved by constructing patterned-wettability surface where the droplet lateral velocity is found to be related to the surface area of a geometric region 36 , 37 . During these rebounding processes, however, satellite drops may still be produced due to Plateau–Rayleigh instability.…”

Section: Introductionmentioning

confidence: 99%

Breaking the symmetry to suppress the Plateau–Rayleigh instability and optimize hydropower utilization

Zhao

et al. 2021

Nat Commun

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Droplet impact on solid surfaces is essential for natural and industrial processes. Particularly, controlling the instability after droplet impact, and avoiding the satellite drops generation, have aroused great interest for its significance in inkjet printing, pesticide spraying, and hydroelectric power collection. Herein, we found that breaking the symmetry of the droplet impact dynamics using patterned-wettability surfaces can suppress the Plateau–Rayleigh instability during the droplet rebounding and improve the energy collection efficiency. Systematic experimental investigation, together with mechanical modeling and numerical simulation, revealed that the asymmetric wettability patterns can regulate the internal liquid flow and reduce the vertical velocity gradient inside the droplet, thus suppressing the instability during droplet rebounding and eliminating the satellite drops. Accordingly, the droplet energy utilization was promoted, as demonstrated by the improved hydroelectric power generation efficiency by 36.5%. These findings deepen the understanding of the wettability-induced asymmetrical droplet dynamics during the liquid–solid interactions, and facilitate related applications such as hydroelectric power generation and materials transportation.

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“…Adhesion and pinning forces of droplets to surfaces govern their motion and dynamics. , These transport phenomena are highly important for controlling fluids at interfaces, collection and removal, or accumulation of liquids at specific places . These are especially relevant to heat transfer across interfaces, inkjet printing and surface patterning, , and collecting condensed water in applications such as fog and dew harvesting .…”

mentioning

confidence: 99%

“…These are especially relevant to heat transfer across interfaces, inkjet printing and surface patterning, , and collecting condensed water in applications such as fog and dew harvesting . In addition, adhesion forces also govern the dynamics of fundamental wetting phenomena, including droplet impact and bouncing, , condensation and evaporation, and droplet sliding …”

mentioning

confidence: 99%

“…5 These are especially relevant to heat transfer across interfaces, 6 inkjet printing and surface patterning, 7,8 and collecting condensed water in applications such as fog and dew harvesting. 9 In addition, adhesion forces also govern the dynamics of fundamental wetting phenomena, including droplet impact 10 and bouncing, 4,11 condensation and evaporation, 11 and droplet sliding. 12 The adhesion forces of droplets to surfaces are derived from the contact angle (CA) hysteresis, 13,14 namely the difference between the advancing and receding contact angles of the moving droplet.…”

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confidence: 99%

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How Droplets Move on Surfaces with Directional Chemical Heterogeneities

Pinchasik

2021

J. Phys. Chem. Lett.

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The nature of adhesion of droplets to surfaces is a long pending scientific question. With the evolution of complex surfaces, quantification and prediction of these adhesion forces become intricate. Nevertheless, understanding these forces is highly relevant for explaining liquid transport in nature and establishing design guidelines for manmade interfaces. Here, it is shown that adhesion of droplets is highly sensitive to the direction of chemical heterogeneities, both in the static and dynamic regimes. This dependency is quantified by bending beam and droplet roll-off experiments. The shape of the fluid contact line on the microscale elucidates the origin of the direction-dependent adhesion. Namely, the droplet receding part pins to a higher number of patches when moving toward to the apex in comparison to the opposite direction. These findings improve the understanding of droplet adhesion to surfaces with chemical heterogeneities and directional transport phenomena.

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Lateral motion of a droplet impacting on a wettability-patterned surface: numerical and theoretical studies

Abstract: A general parameter of effective retraction area has been established to connect the wettability patterns with droplet lateral motion.

Cited by 8 publications

References 43 publications

Lateral motion of a solid with a heterogeneous wettability surface driven by impacting droplets

Lateral motion of a solid with a heterogeneous wettability surface driven by impacting droplets

Breaking the symmetry to suppress the Plateau–Rayleigh instability and optimize hydropower utilization

How Droplets Move on Surfaces with Directional Chemical Heterogeneities

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