Determination of contact angle of droplet on convex and concave spherical surfaces

Wu, Dongyin; Wang, Pengfei; Wu, Peng; Yang, Qingzhen; Liu, Fusheng; Han, Yu; Feng, Xiuli; Wang, Lin

doi:10.1016/j.chemphys.2015.05.020

Cited by 46 publications

(44 citation statements)

References 26 publications

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“…Then, the critical contact angle θ ls for the free and the Cassie droplet becomes θ ls ∼ 17 • on a spherical substrate and θ ls ∼ 21 • in a spherical cavity from Eq. (21). Furthermore, if the roughness is r s = 1.6 and the Young's contact angle is θ Y = 20 • and, therefore, r s cos θ Y −1 ≃ 0.50, for example, the critical contact angle for the Wenzel droplet becomes θ ls ∼ 1.4 • on a spherical substrate and θ ls ∼ 3.0 • in a spherical cavity from Eq.…”

Section: Energy Balance Approachmentioning

confidence: 97%

“…Physically, however, the existence of this stage IV when θ < θ ls and θ < θ vf itself is a delicate problem as the scaled line tensionτ can be very small and, therefore, θ ls defined by Eqs. (21) and (22) can be a microscopic atomic scale. Then, our formulation based on the energy balance approach in Sec.…”

Section: Four Stages Of Spreading On a Spherical Substrate And Imentioning

confidence: 99%

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Four stages of droplet spreading on a spherical substrate and in a spherical cavity: Surface tension versus line tension and viscous dissipation versus frictional dissipation

Iwamatsu

2018

Phys. Rev. E

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The spreading of a cap-shaped spherical droplet of non-Newtonian power-law liquids on a completely wettable spherical substrate is theoretically studied. Both convex spherical substrates and concave spherical cavities with smooth or rough surfaces are considered. The droplet on a rough substrate is modeled by either the Wenzel or the Cassie-Baxter model. The two sources of driving force of spreading by the surface-tension and the line tension are considered. Also, the two channels of energy dissipation by the viscous dissipation within the bulk and the frictional dissipation at the contact line are considered. A combined theory of spreading on a spherical substrate is constructed by including those four factors. The spreading process is divided into four stages, each of which is governed by one of two driving forces and one of two dissipations. It is found that the dynamic contact angle θ has a characteristic time (t) dependence at each stage. It does not necessarily follow the standard power law θ ∼ t −α . Instead, the relaxation can be a power-law with the exponent α different from that on a flat substrate, or it can be exponential or it can finish within a finite time. Therefore, various spreading scenarios on a spherical substrate and in a spherical cavity are predicted.

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Section: Energy Balance Approachmentioning

confidence: 97%

Section: Four Stages Of Spreading On a Spherical Substrate And Imentioning

confidence: 99%

Four stages of droplet spreading on a spherical substrate and in a spherical cavity: Surface tension versus line tension and viscous dissipation versus frictional dissipation

Iwamatsu

2018

Phys. Rev. E

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“…It is generally believed that as the contact angle increases, the hydrophobic property improves. Therefore, the contact angle is an important index to reveal hydrophobic and super-hydrophobic properties [44][45][46][47].…”

Section: Hydrophobic Performancementioning

confidence: 99%

Hydrophobic and Anti-Fouling Performance of Surface on Parabolic Morphology

Liu

Yang

Chen

et al. 2020

IJERPH

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The hydrophobicity and anti-fouling properties of materials have important application value in industrial and agricultural production and people's daily life. To study the relationship between the unit width L 0 of the parabolic hydrophobic material and the hydrophobicity and anti-fouling properties, the rough surface structure of the parabolic with different widths was prepared by grinding with different SiC sandpapers, and further, to obtain hydrophobic materials through chemical oxidation and chemical etching, and modification with stearic acid (SA). The morphology, surface wetting and anti-fouling properties of the modified materials were characterized by SEM and contact angle measurement. The oil-water separation performance and self-cleaning performance of the materials were explored. The surface of the modified copper sheet forms a rough structure similar to a paraboloid. When ground with 1500 grit SiC sandpaper, it is more conducive to increase the hydrophobicity of the copper sheet surface and increase the contact angle of water droplets on the copper surface. Additionally, the self-cleaning and anti-fouling experiments showed that as L 0 decreases, copper sheets were less able to stick to foreign things such as soil, and the better the self-cleaning and anti-fouling performance was. Based on the oil-water separation experiment of copper mesh, the lower L 0 has a higher oil-water separation efficiency. The results showed that material with parabolic morphology has great self-cleaning, anti-fouling, and oil-water separation performance. The smaller the L 0 was, the larger the contact angle and the better hydrophobic performance and self-cleaning performance were.

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“…Their approach was able to approve that surface roughness and energetic heterogeneities a ected the contact angle. Wu et al [18] proposed a theoretical model to estimate the contact angle of droplets on convex and concave surfaces. This model mainly depends on droplet volume, surface curvature, and the contact angle of the droplet on a at surface.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Sessile and Pendant Droplets Shape on Inclined and Curved Surfaces

et al. 2018

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Abstract. In this study, shapes of water droplets with di erent sizes on various inclined smooth surfaces are simulated numerically, and advancing and receding contact angles are determined using the molecular dynamics approach. Experimental measurements are also carried out to validate the numerical predictions of droplets' shape on inclined surfaces. Based on the veri ed code, shapes of water droplets with di erent sizes around smooth circular cylinders with various diameters are simulated. Furthermore, advancing and receding contact angles along with the hysteresis values of the sessile and pendant droplets with various sizes around the cylinders are evaluated. Finally, based on the numerical results, two correlations are developed to predict advancing and receding contact angles of droplets on the circular cylinders. According to the results, maximum advancing and minimum receding angles take place on both sides of the cylinder on a horizontal line passing through the cylinder center. As a result, contact angle hysteresis reaches its maximum value in these two positions. In addition, advancing and receding angles have the same values on the top and bottom of the cylinder. Moreover, droplet size and cylinder diameter have minor e ect, while drop position has major e ect on the shape of droplets over the cylinder.

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Determination of contact angle of droplet on convex and concave spherical surfaces

Cited by 46 publications

References 26 publications

Four stages of droplet spreading on a spherical substrate and in a spherical cavity: Surface tension versus line tension and viscous dissipation versus frictional dissipation

Four stages of droplet spreading on a spherical substrate and in a spherical cavity: Surface tension versus line tension and viscous dissipation versus frictional dissipation

Hydrophobic and Anti-Fouling Performance of Surface on Parabolic Morphology

Molecular Dynamics Simulations of Sessile and Pendant Droplets Shape on Inclined and Curved Surfaces

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