Asymmetric capillary bridges between contacting spheres

Farmer, Timothy; Bird, James

doi:10.1016/j.jcis.2015.04.045

Cited by 47 publications

(32 citation statements)

References 34 publications

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“…Visual inspection shows that during the initial wetting phase the meniscus shape is rapidly evolving; it grows in volume, expands along the contact line and the contact angle increases ranging from approximately 60 • (Figure 2c) to 120 • (Figure 2g). Such a result may be considered to agree with the findings of [18], who showed that a liquid bridge may change from a concave to a convex shape as its volume increases. However, here, the significant difference in the shape of the sand particles to the hydrophilic glass beads tested in [18], as well as the change in hydrophobicity, should be considered.…”

Section: Experimental Campaignsupporting

confidence: 90%

“…Such a result may be considered to agree with the findings of [18], who showed that a liquid bridge may change from a concave to a convex shape as its volume increases. However, here, the significant difference in the shape of the sand particles to the hydrophilic glass beads tested in [18], as well as the change in hydrophobicity, should be considered. Testing completed on hydrophilic sand, prepared to the same degree of packing (to be discussed in detail in an upcoming work), showed no evidence of convex menisci.…”

Section: Experimental Campaignsupporting

confidence: 90%

“…negative pore water pressure) [17]. There is evidence, however, that above a critical volume of water, the liquid bridge between hydrophilic spheres may adopt an asymmetric, convex shape [18]. According to [19]: 'water can be used as a test liquid to establish (via the advancing contact angle, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Effect of wetting and drying on meniscus structures in hydrophobic sands

et al. 2020

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Hydrophobic soils can occur either naturally when particles are coated with plant-derived hydropho-bic organic compounds or if exposed to very high temperatures, or artificially if treated with contaminated water or chemicals in the laboratory. Hydrophobic soils can resist water infiltration, are associated with preferential flow and may lead to increased surface runoff and soil erosion. Traditional understanding of unsaturated hy-drophobic soils suggests that convex water menisci, and so positive water pressures, should form between soil particles, due to contact angles > 90◦. However, experimental results do not support this theory. The objective of this work was to study the changes in meniscus structures in hydrophobic sand specimens, as well as the overall response of the sand to wetting and drying cycles. A very uniform, fine silica sand was mixed with Dimethyldichlorosilane to induce water repellence. Successive images captured in an environmental scanning electron microscope are presented, to examine the response of the sand in two distinct drying and wetting cycles. Preliminary results show that the non-spherical nature of the sand particles prevent or hinder the formation of convex liquid bridges, despite the high contact angles. Rather, water droplets appear to expand only through droplet coalescence, which prevents structures from contracting on drying.

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Section: Experimental Campaignsupporting

confidence: 90%

Section: Experimental Campaignsupporting

confidence: 90%

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Effect of wetting and drying on meniscus structures in hydrophobic sands

et al. 2020

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“…In such a case, the requirement of a constant equilibrium contact angle over a solid surface imposes the constraint that, close to the contact line, the boundaries are solids of revolution about an axis passing through the centre of the sphere. It is straightforward to apply this criterion to find the force-free equilibrium states of capillary bridges between flat and curved walls [10][11][12][13][14][15], but also those of droplets in contact with suspended solid particles, such as Pickering emulsions [16] and liquid marbles [17,18].…”

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confidence: 99%

Energy Invariance in Capillary Systems

Ruiz-Gutiérrez

Guan

et al. 2017

Phys. Rev. Lett.

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We demonstrate the continuous translational invariance of the energy of a capillary surface in contact with reconfigurable solid boundaries. We present a theoretical approach to find the energyinvariant equilibria of spherical capillary surfaces in contact with solid boundaries of arbitrary shape and examine the implications of dynamic frictional forces upon a reconfiguration of the boundaries.Experimentally, we realise our ideas by manipulating the position of a droplet in a wedge geometry using lubricant-impregnated solid surfaces, which eliminate the contact-angle hysteresis and provide a test bed for quantifying dissipative losses out of equilibrium. Our experiments show that dissipative energy losses for an otherwise energy-invariant reconfiguration are relatively small, provided that the actuation timescale is longer than the typical relaxation timescale of the capillary surface. We discuss the wider applicability of our ideas as a pathway for liquid manipulation at no potential energy cost in low-pinning, low-friction situations.

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“…The configuration and adhesion force of a very small liquid bridge (within the volume of a few mL) have been reported between two rigid surfaces, such as two parallel surfaces, two spheres, or a sphere and a plane surface. [15][16][17] However, a liquid bridge of a larger scale (could be more than 16 mL) between flexible materials such as fabrics are quite different, and are rarely reported. Previous studies 11,13,18 showed that the adhesion properties of wet fabrics are intricately related to tensile and bending properties, hydrophilicity, structure of the material, and surface tension of the liquid.…”

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confidence: 99%

The influence of surface hydrophilicity on the adhesion properties of wet fabrics or films to water

Lou

Qiu

Jin

et al. 2017

Textile Research Journal

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The adherence of wet fabrics to the skin brings much discomfort. The relationship between hydrophilicity and adhesion properties of fabric materials is investigated. A theoretical expression is given to describe the relationship of adhesion force, water contact angle (WCA), and radius of fabric–liquid interface. The adhesion force grows with decreasing WCA and increasing radius of the fabric–liquid interface. With the help of atmospheric pressure plasma jet (APPJ) treatment, the hydrophilicity of the fabric materials is improved, accompanied by reduced WCA, roughened fiber surfaces, as observed by scanning electronic microscope (SEM), and increased Oxygen/Carbon (O/C) atomic ratio and polar bonds, analyzed by X-ray photoelectron spectroscopy (XPS). In accordance with the theoretical conclusion, the APPJ treated fabrics have a much larger maximum adhesion force and longer adhesion duration with water, indicating more discomfort resulting from the increase of hydrophilicity when they are wet. To minimize the discomfort caused by wet adhesion, less hydrophilic fabric surfaces may be preferred.

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Asymmetric capillary bridges between contacting spheres

Cited by 47 publications

References 34 publications

Effect of wetting and drying on meniscus structures in hydrophobic sands

Effect of wetting and drying on meniscus structures in hydrophobic sands

Energy Invariance in Capillary Systems

The influence of surface hydrophilicity on the adhesion properties of wet fabrics or films to water

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