Experimental and numerical studies on liquid bridge formed among three spheres

Experiments on five-, four-, three-and two-wet-hydrophilic-grain clusters were performed to investigate evolution of adhesion of granular media during drying on the micro-scale. The experiments show that the adhesion-force of a cluster initially grows at most to three times the original value before decreasing to zero by the end of evaporation. The adhesion-force is composed of capillary pressure force acting over the liquid/solid contact surface area, and surface tension forces acting over the three-phase contact perimeter length. This is in contrast with most macro-scale phenomenological models, in which the only desaturation process variables affecting strength are suction and saturation. Both the contact surface area and contact perimeter length are reduced to zero upon complete liquid evaporation. The morphology of an evaporating water body evolves through slow flow controlled by evaporation rate, interrupted by various modes of fast air entry, which are non-equilibrium jumps of liquid/gas interfaces (Haines jumps). The instabilities involve large adhesion force discontinuities and substantial water mass reconfiguration with water flow in an extremely short time, which makes the process transient. The reconfigurations can reduce the original multi-grain water clusters to four-, three-and two-grain clusters by way of three different instability modes: of thin-sheet instability, or meniscus snap-through instability, depending on the sign of the Gauss curvature of the liquid surface, or finally, for two-grain bridges only, a liquid wire pinch-off. For larger meso-scale assemblies, however, the global adhesionforce evolution is little affected by the jumps. The air entries are potential sites for drying cracks. The (approximately) calculated capillary pressure for two-and three-grain clusters, in no cases is seen to reach high values, predicted from water retention curves.

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“…Lian et al, 1993). An analogous argument has been made for three-grain bridges by Murase et al (2004Murase et al ( , 2008.…”

Section: Micro-scale Experimentsmentioning

confidence: 54%

Adhesion-force micro-scale study of desiccating granular material

2020

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“…For systems in funicular or pendular states there is no maximum on the stress-strain curve for the current geometry used, but it would appear if the gap size was smaller. Experimental evidence for two-particle [14,16] or three-particle [17] systems shows a monotonous decrease in capillary force only, however, these measurements have been carried for a 3-D liquid bridge geometry. Because the funicular bridge is non-symmetric the tensile strength is anisotropic.…”

Section: Simple Four-particle Geometrymentioning

confidence: 90%

The strength of liquid bridges in random granular materials

Grof

Lawrence

Štěpánek

2008

Journal of Colloid and Interface Science

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“…This is due to the differing properties of the liquid bridges formed between particles during the process. Many authors have investigated the formation of liquid bridges at the micro-scale, investigating both static and dynamic liquid bridge properties for systems involving two or three particles [47][48][49][50][51][52][53][54][55]. Liquid viscosity has been shown to have a large impact on the bridge strength, the rupture distance, and the subsequent redistribution of the liquid [56][57][58][59][60].…”

Section: However In Their Dem Simulations Specific To Liquid Contactmentioning

confidence: 99%