Numerical study of wetting stability and sliding behavior of liquid droplets on microgrooved surfaces

Goswami, Abir; Alen, Saif Khan; Farhat, Nazia; Rahman, Ashiqur

doi:10.1007/s00396-019-04527-0

Cited by 9 publications

(6 citation statements)

References 61 publications

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“…On such surfaces, the so-called Cassie drops [14] exhibit high contact angles and low CAH. Such drops can be released by adding a small amount of energy by tilting the surface [15][16][17][18] or increasing the mass of the drop. [19] To allow controlled trapping and release of drops on surfaces, the energy of the system should be controlled such that the drop is lightly trapped and can be released by adding a small amount of energy to overcome this barrier.…”

Section: Introductionmentioning

confidence: 99%

Controlled Trapping and Release of Droplets through Dynamically Reconfigurable Surfaces

Rajak,

Rühe

2024

Adv Materials Inter

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Most previous publications attempt to control the trapping and release of liquid droplets on a surface through tuning the surface energy of the substrate, for example, by photoisomerization. In this work, the energy barrier between the trapped and released state is raised or lowered by controlling the droplet contact area. This is achieved by designing a dynamically reconfigurable surface where an external stimulus is used to change the surface topography. The system consists of two microstructured components, one being ridges separated by microtrenches and the other a perforated membrane. They are aligned in such a way that the ridges can be raised or lowered through the perforations with the help of a piezo drive. This way the topography changes from surfaces consisting of hills to one consisting of holes – and back again. This dynamic surface reconfiguration changes the contact area such that drops resting or rolling on them become captured or released on demand.

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Section: Introductionmentioning

confidence: 99%

Controlled Trapping and Release of Droplets through Dynamically Reconfigurable Surfaces

Rajak,

Rühe

2024

Adv Materials Inter

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“…Based on this phenomenon, a prediction model was created, and it was discovered that the SA was completely governed by the ratio of the solid−liquid interface area, droplet volume, and Young's contact angle. In addition to the experimental methods for SA prediction, Goswami et al 19 established a three-dimensional droplet model to investigate the droplet stability and repeatability of three-phase contact lines on horizontal and inclined microgroove solid surfaces. When the droplet morphologies of the numerical model and critical SAs were compared to the experimental data, they were discovered to be similar.…”

Section: ■ Introductionmentioning

confidence: 99%

Predicting Sliding Angles on Random Pit-Distributed Textures Using Probabilistic Neural Networks

Wang

Di³

et al. 2023

Langmuir

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The three-phase contact line best reflects the sliding ability of droplets on solid surfaces. Most studies on the sliding angle (SA) of superhydrophobic surfaces are limited to regularly arranged microtextured surfaces, lacking definite models and effective methods for a complex surface of a random texture. In this study, random pits with an area ratio of 19% were generated on 1 mm × 1 mm subregions, and the subregions formed arrays on a sample surface of 10 mm × 10 mm to obtain a randomly distributed microtexture surface with no pit overlaps. Although the contact angle (CA) of randomly pitted texture was the same, the SA was different. The SA of surfaces was affected by the pit location. The location of random pits increased the complexity of the three-phase contact line movement. The continuity of the three-phase contact angle (T) can reveal the rolling mechanism of the random pit texture and predict the SA, but the relationship between the T and SA is a relatively poor linear relation (R 2 = 74%), and the SA of the random pit texture can only be roughly estimated. The quantized pit coordinates and SA were used as the input and output labels for the PNN model, respectively, and the accuracy of the model convergence was 90.2%.

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“…[31][32][33][34][35][36] Miwa et al reported an inverse relationship between the static contact and sliding angles with an increase in the static contact angle of a droplet being associated with a decrease in the sliding angle 37 and several investigators have conducted related theoretical studies of various surface morphologies. [38][39][40][41][42][43] The motion of a water droplet on a solid surface is governed by the movement of the threephase liquid-vapor-solid contact line. With this in mind, Yoshimitsu et al reported that it is important to design a surface with respect to the shape and movement of the contact line when they investigated the sliding angle of water droplets on hydrophobic surfaces with grooved and pillared structures.…”

Section: Introductionmentioning

confidence: 99%

“…Superhydrophobic surfaces have attracted great interest due to their importance in a wide range of applications including self-cleaning, − anticorrosion, − water/oil separation, − anti-icing, − and drag reduction. ,− These surfaces induce large static contact angles (>150°) in water droplets, while they facilitate droplet movement along the surface with small sliding angles (<5°) and low contact-angle hysteresis. − Static contact angles are commonly measured to evaluate the hydrophobicity of a surface and the effects that surface texture has on this property. − Miwa et al reported an inverse relationship between the static contact and sliding angles with an increase in the static contact angle of a droplet being associated with a decrease in the sliding angle, and several investigators have conducted related theoretical studies of various surface morphologies. − …”

Section: Introductionmentioning

confidence: 99%

Influence of Gravity on the Sliding Angle of Water Drops on Nanopillared Superhydrophobic Surfaces

Yan

Fichthorn

2020

Langmuir

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Molecular dynamics (MD) simulations were used to study the effects of gravity, solid surface energy, and fraction of water-solid interface area on water droplet sliding angles on nanopillared surfaces. To effectively simulate the influence of gravity on drop sliding, we developed a protocol in which we scale the value of gravitational acceleration used in our simulations according to the Bond number (Bo). In this way, we approximate the behavior of 2 larger drops than we can effectively simulate using MD. The sliding angle decreased with an increase in Bo, while increasing with an increase in the liquid-solid surface interaction. The sliding angles exhibit a minimum with an increase in the fraction of water-solid interface area, due to meniscus formation at high fractions. Trends predicted by our model are in agreement with experiment. Using our model, we investigated the mechanisms of droplet movement along nanopillared surfaces. Depending on the pinning state of the droplets at equilibrium, either the advancing or receding contact angle initiates motion. Moreover, the minimum dynamic advancing and receding contact angles of drops with gravity are close to the static contact angle and the intrinsic contact angle, respectively, while the maximum of both angles are as large as 180°. We find that the drops move through a combination of sliding and rolling, in agreement with experiment. Our studies offer clarity to conflicting experimental reports and present new results awaiting experimental confirmation.

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Numerical study of wetting stability and sliding behavior of liquid droplets on microgrooved surfaces

Cited by 9 publications

References 61 publications

Controlled Trapping and Release of Droplets through Dynamically Reconfigurable Surfaces

Controlled Trapping and Release of Droplets through Dynamically Reconfigurable Surfaces

Predicting Sliding Angles on Random Pit-Distributed Textures Using Probabilistic Neural Networks

Influence of Gravity on the Sliding Angle of Water Drops on Nanopillared Superhydrophobic Surfaces

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