Contact time on curved superhydrophobic surfaces

Han, Jeonghoon; Kim, Wonjung; Bae, Changwoo; Lee, Dong‐Wook; Shin, Seungwon; Nam, Youngsuk; Lee, Choongyeop

doi:10.1103/physreve.101.043108

Cited by 37 publications

(47 citation statements)

References 41 publications

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“…Other relevant references also corroborated the same conclusion. [16][17][18]26,27 Previous studies have shown that when impacting a cylinder, a droplet is more likely to deposit on a hydrophilic surface or rebound from a superhydrophobic surface. 7,24,28−30 However, on a hydrophobic cylinder, a droplet shows different dynamic behaviors from a hydrophilic or a superhydrophobic one.…”

Section: ■ Introductionmentioning

confidence: 99%

Impact Dynamics of a Single Droplet on Hydrophobic Cylinders: A Lattice Boltzmann Study

Zhang

Wang

et al. 2022

Langmuir

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This study numerically investigates the effects of the Weber number (We) and cylinder-to-droplet radius ratio (R*) on the impact dynamics of a lowviscosity droplet on a hydrophobic cylinder by the lattice Boltzmann method. The intrinsic contact angle of the surface is chosen as θ 0 = 122°± 2°, which ensures a representative hydrophobicity. The regime diagram of the impact dynamics in the parameter space of We versus R* is established with categories of split and nonsplit regimes. The droplet would split during impact as α = We/R* exceeds a critical value. In the nonsplit regime, the droplet bounces off the cylinder at most Weber numbers unless the impact velocity is minuscule (We < 2). The contact time of the droplet on the cylinder surface decreases with increasing R* or decreasing We, indicating bouncing is facilitated under such conditions. This can be explained by the suppressed adhesion dissipation between the droplet and surface due to a reduction in the contact area. In the split regime, sufficient kinetic energy inside the impacting droplet determines whether the whole droplet could detach from the surface. With a small cylinder (R* < 0.83) and large We (>25), the adhesion effect is weakened for the side fragments because of the small contact area, and it facilitates the dripping of fragments. For other conditions, the detachment, especially for the tiny droplet on the cylinder top, only occurs if the deformation is prominent at We > 35. Moreover, the spreading dynamics of the impacting droplet are also highlighted in this work.

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Section: ■ Introductionmentioning

confidence: 99%

Impact Dynamics of a Single Droplet on Hydrophobic Cylinders: A Lattice Boltzmann Study

Zhang

Wang

et al. 2022

Langmuir

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“…Hao et al 17 used high-speed photography to study the effects of oblique drops impacting on smooth surfaces under different dip angles and pressures and showed that increasing the dip angle or decreasing the environmental pressure could completely inhibit drop spatter. Han et al 18 proposed that the asymmetric expansion on the surface is driven by either the Coanda effect or inertia, depending on the ratio of the drop diameter to the curvature diameter. Lu et al 19 studied the phenomenon of drops hitting a homogeneous structure with a superhydrophobic surface with a nonwettability gradient and found that the falling drop mainly deviates toward regions of weaker hydrophobicity because of water repellency.…”

Section: ■ Introductionmentioning

confidence: 99%

Lateral Drop Rebound on a Hydrophobic and Chemically Heterogeneous Surface

Pan

Shao

et al. 2021

Langmuir

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A drop rebounding from a hydrophobic and chemically heterogeneous surface is investigated using the multiphase lattice Boltzmann method. The behaviors of drop rebounding are dependent on the degrees of the hydrophobicity and heterogeneity of the surface. When the surface is homogeneous, the drop rebounds vertically and the height is getting higher and higher with increases of the surface hydrophobicity. When the surface consists of two different hydrophobic surfaces, the drop rebounds laterally towards the low hydrophobic side. The asymmetrical rebounding is because the unbalanced Young's force exerted on the contact line by the high hydrophobic side is greater than that by the low hydrophobic surface. A set of contours of momentum distribution illustrate the dynamic process of drop spreading, shrinking and rebounding. This work promotes the understanding of the rebound mechanism of a drop impacting the surface and also provides a guiding strategy for precisely controlling the lateral behavior of rebounding drops by hydrophobic degrees and heterogeneous surfaces.

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“…Readers can find more detailed information about our existing numerical framework in our previous studies; Juric (2002, 2009), Shin et al (2005Shin et al ( , 2018, Shin (2021b, 2021c). It is also worthwhile mentioning that these numerical methods considered here have been rigorously validated with many existing experimental studies for a wide range of collision conditions (Choi and Shin, 2019;Yoon and Shin, 2021a, 2021b, 2021c and have also been applied to diverse studies of droplet collision phenomena which include collision with a stationary particle (Yoon and Shin, 2021a, 2021b, 2021c, a moving particle (Choi and Shin, 2019), a cylindrical wire (Han et al, 2020), a flat surface (Shin et al, 2018) and a liquid pool (Shin et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

“…As mentioned before, an AMR strategy for mid-air droplet-particle simulations is essential for computing efficiency with limited computational resources. Although our computational framework based on the LCRM has been extensively applied to various simulations of multiphase flow problems (Choi and Shin, 2019;Han et al, 2020; 2017; Yoon and Shin, 2021a;2021b) and even was successfully parallelized for highperformance computational resources (Shin et al, 2017) in fully three-dimensional problems, an AMR technique has not yet been applied for this framework.…”

Section: Simple Dual Grid Based Adaptive Mesh Refinement Strategymentioning

confidence: 99%

“…One of the popular strategies for reducing the computational cost is to employ an adaptive mesh refinement (AMR) technique, which generally incorporates regions of varying grid resolution within the overall computational domain (Berger and Colella, 1989;Popinet, 2003;Sussman et al, 1999). While well-known methods for the simulation of multiphase flows such as Volume-of-Fluid, Level-Set, and Front-Tracking have adopted a variety of appropriate AMR techniques (Agresar et al, 1998;Popinet, 2003), an AMR technique for our simulation framework has not yet been developed, even though our work has previously been widely applied to various droplet collision phenomena (Choi and Shin, 2019;Han et al, 2020;Shin et al, 2017;Yoon and Shin, 2021a, 2021b, 2021c and successfully parallelized (Shin et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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