Maximum Spreading of Liquid Drops Impacting on Groove-Textured Surfaces: Effect of Surface Texture

Vaikuntanathan, Visakh; Sivakumar, D.

doi:10.1021/acs.langmuir.5b04639

Cited by 70 publications

(58 citation statements)

References 30 publications

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“…Similarly, the spreading in the longitudinal direction increases with increase in Weber number on V-shape microgrooved surface for We = [1, 100], as reported in Ref. [27]. The critical velocity for the Cassie to Wenzel wetting transition was found to be function of geometry and wetting characteristics of the base surface for a V-shape microgrooved surface [28].…”

Section: Introductionsupporting

confidence: 70%

“…At p/D0 = 0.028, the droplet bouncing is first observed at We = 6.5 with lower ε (~ 0.3) because it has larger wettability in comparison to surfaces with p/D0 = 0.037 and p/D0 = 0.045. In addition, the droplet experiences more number of ridges beneath it for p/D0 = 0.028, which leads to more dissipation of the kinetic energy (which lowers ε) due to pinning and depinning of advancing or receding contact line [27]. Therefore, the coefficient of restitution is the largest for CB at the largest pitch considered and at an optimal Weber number.…”

Section: Regime Mapmentioning

confidence: 99%

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Droplet Bouncing and Breakup during Impact on a Microgrooved Surface

et al. 2017

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We experimentally investigate impact dynamics of a microliter water droplet on a hydrophobic microgrooved surface. The surface is fabricated using photolithography and high-speed visualization is employed to record the time-varying droplet shapes in transverse as well as longitudinal direction. The effect of the pitch of the grooved surface and Weber number on droplet dynamics and impact outcome are studied. At low pitch and Weber number, the maximum droplet spreading is found to be greater in the longitudinal direction than the transverse direction to the grooves. The preferential spreading inversely scales with the pitch at a given Weber number. In this case, the outcome is no bouncing (NB); however, this changes at larger pitch or Weber number. Under these conditions, the following outcomes are obtained as function of the pitch and Weber number -droplet completely bounces off the surface (CB), bouncing occurs with droplet breakup (BDB) or no bouncing due to Cassie to Wenzel wetting transition (NBW). In BDB and NBW, the liquid penetrates the grooves partially or completely beneath the droplet due to the wetting transition. The former results in droplet breakup alongside bouncing while the latter suppresses the bouncing. These outcomes are demarcated on Weber number -dimensionless pitch plane and the proposed regime map suggests the existence of a critical Weber number or pitch for the transition from one regime to the other. CB and BDB are quantified by plotting coefficient of restitution of the bouncing droplet and volume of daughter droplet left on the surface, respectively. The critical Weber number needed for the transition from CB to BDB is estimated using an existing mathematical model and is compared with the measurements. The comparison is good and provides insights in mechanism of the liquid penetration into the grooves. The present results on microgrooved surfaces are compared with published results on micropillared surfaces in order to assess water repelling properties of the two surfaces.3

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Section: Introductionsupporting

confidence: 70%

Section: Regime Mapmentioning

confidence: 99%

Droplet Bouncing and Breakup during Impact on a Microgrooved Surface

et al. 2017

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“…Substrate roughness is another parameter that can influence the droplet impact dynamics [33][34][35][36][37] .…”

Section: Introductionmentioning

confidence: 99%

“…Droplet impact on regular micro-textured substrates 33,34,38 show that β max is influenced by the substrate topography. Even a substrate with small aspect ratio roughness hinders droplet spreading 35 , although the effect becomes less pronounced.…”

Section: Introductionmentioning

confidence: 99%

“…We treat the contact line friction parameter µ f as a material property for each combination of air-liquid-solid, which should be independent of the impact speed. We determine the magnitude of µ f by directly comparing the numerical simulations with several independent experiments 23,25,32,34,35 . Our assumption of linear response through a Stokes-like drag at the contact line shows that the simulations can accurately reproduce experimental observations.…”

Section: Introductionmentioning

confidence: 99%

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Local dissipation limits the dynamics of impacting droplets on smooth and rough substrates

2017

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A droplet that impacts onto a solid substrate deforms in a complex dynamics. To extract the principal mechanisms that dominate this dynamics we deploy numerical simulations based on the phase field method. Direct comparison with experiments suggests that a dissipation local to the contact line limits the droplet spreading dynamics and its scaled maximum spreading radius β max . By assuming linear response through a drag force at the contact line, our simulations rationalize experimental observations for droplet impact on both smooth and rough substrates, measured through a single contact line friction parameter µ f . Moreover, our analysis shows that at low and intermediate impact speeds dissipation at the contact line limits the dynamics and we describe β max by the scaling law β max ∼ (Reµ l /µ f ) 1/2 that is a function of the droplet viscosity (µ l ) and its Reynolds number (Re).

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Understanding and Utilizing Droplet Impact on Superhydrophobic Surfaces: Phenomena, Mechanisms, Regulations, Applications, and Beyond

Hu,

Chu,

Shan

et al. 2023

Advanced Materials

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Droplet impact is a ubiquitous liquid behavior that closely tied to human life and production, making indispensable impacts on the big world. Nature‐inspired superhydrophobic surfaces provide a powerful platform for regulating droplet impact dynamics. The collision between classic phenomena of droplet impact and the advanced manufacture of superhydrophobic surfaces is lighting up the future. Accurately understanding, predicting, and tailoring droplet dynamic behaviors on superhydrophobic surfaces are progressive steps to integrate the droplet impact into versatile applications and further improve the efficiency. In this review, the progress on phenomena, mechanisms, regulations, and applications of droplet impact on superhydrophobic surfaces, bridging the gap between droplet impact, superhydrophobic surfaces, and engineering applications are comprehensively summarized. It is highlighted that droplet contact and rebound are two focal points, and their fundamentals and dynamic regulations on elaborately designed superhydrophobic surfaces are discussed in detail. For the first time, diverse applications are classified into four categories according to the requirements for droplet contact and rebound. The remaining challenges are also pointed out and future directions to trigger subsequent research on droplet impact from both scientific and applied perspectives are outlined. The review is expected to provide a general framework for understanding and utilizing droplet impact.

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Maximum Spreading of Liquid Drops Impacting on Groove-Textured Surfaces: Effect of Surface Texture

Cited by 70 publications

References 30 publications

Droplet Bouncing and Breakup during Impact on a Microgrooved Surface

Droplet Bouncing and Breakup during Impact on a Microgrooved Surface

Local dissipation limits the dynamics of impacting droplets on smooth and rough substrates

Understanding and Utilizing Droplet Impact on Superhydrophobic Surfaces: Phenomena, Mechanisms, Regulations, Applications, and Beyond

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