Role of contact-angle hysteresis for fluid transport in wet granular matter

Mani, Roman; Semprebon, Ciro; Kadau, Dirk; Herrmann, Hans J.; Brinkmann, Martin; Herminghaus, Stephan

doi:10.1103/physreve.91.042204

Cited by 18 publications

(17 citation statements)

References 24 publications

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“…Adding to complexity, the contact angle is also dependent on the hydraulic loading path; its value showing a hysteresis between extreme limits that correspond to receding or advancing contact lines. Such hysteresis has now be shown to affect the fluid phase distribution [25].…”

Section: Introductionmentioning

confidence: 96%

Contact angle mechanical influence in wet granular soils

Duriez

Wan

2016

Acta Geotech.

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We investigate the macroscopic mechanical influence of the local liquid-solid contact angle that governs the fluid distribution in granular soils under unsaturated conditions. To this end, a Discrete Element Method (DEM) based implementation that accommodates for any contact angle is proposed and applied to an idealized granular material in the pendular regime. The DEM model includes resultant capillary forces as well as a comprehensive description of the capillary bridges (volume, surface, orientation tensor) by solving the Laplace-Young equation in a general case, instead of using any unnecessary phenomenological relation. Macroscale mechanical simulations for different constant contact angle values reveal that granular assemblies are less sensitive to unsaturated conditions for higher contact angles, which is in line with the contact angle influence at the microscopic capillary bridge

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Section: Introductionmentioning

confidence: 96%

Contact angle mechanical influence in wet granular soils

Duriez

Wan

2016

Acta Geotech.

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“…A better understanding of the liquid structures emerging in the funicular regime and the capillary cohesion caused by them may help to predict landslides or avalanches [16], and to complement existing models for technological applications in wet aggregation or particle coating [17]. Besides the mechanics of wet granulates, modeling the cluster morphology of partially wetting liquids will also have repercussions on the theory of fluid transport in wet granular beds [10,15,[18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Liquid morphologies and capillary forces between three spherical beads

et al. 2016

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Equilibrium shapes of coalesced pendular bridges in a static assembly of spherical beads are computed by numerical minimization of the interfacial energy. Our present study focuses on generic bead configurations involving three beads, one of which is in contact to the two others while there is a gap of variable size between the latter. In agreement with previous experimental studies, we find interfacial 'trimer' morphologies consisting of three coalesced pendular bridges, and 'dimers' of two coalesced bridges. In a certain range of the gap opening we observe a bistability between the dimer and trimer morphology during shrinking and growth. The magnitude of the corresponding capillary forces in presence of a trimer or dimer depends, besides the gap opening only on the volume or Laplace pressure of liquid. For a given Laplace pressure, the capillary forces in presence of a trimer are slightly larger than the force of a single bridges at the same gap opening, which could explain the shallow maximum and plateau of the capillary cohesion of a wetting liquid for saturations in the funicular regime.

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“…Recent results by Mani et al [23][24][25] show from experiments and simulations that the liquid content decreases within wet shear bands. This is a diffusion-driven phenomenon occurring at larger amount of shear, which causes the liquid to be transported away from the shear band.…”

Section: Introductionmentioning

confidence: 99%

“…This prompts us to look for a liquid migration model in our discrete element method (DEM) simulations where liquid moves between contacts due to shear-driven liquid bridge formation and rupture. Note that liquid transport fluxes are also driven by Laplace pressure changes [24,[26][27][28], either through the vapor phase or through the wetting layers on the beads [29]. However, this mode of liquid transport is excluded from the discussion in this paper.…”

Section: Introductionmentioning

confidence: 99%

Liquid redistribution in sheared wet granular media

2018

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Shearing wet granular systems causes a redistribution of the interstitial liquid, which can affect the material's bulk behavior. Using the discrete-element method, we study the early rapid transients, the intermediate states, and the slow long-term evolution of liquid redistribution for various material parameters and different initial wetting conditions in an inhomogeneous split-bottom ring-shear cell featuring a wide shear band away from the system walls. In our model, liquid exists in two states, either in liquid bridges between particles or in liquid films on the particle surfaces. Under deformations like shear, the liquid is redistributed due to the rupture of existing and formation of new liquid bridges. Since we assume the immediate redistribution limit as a new model parameter, a liquid bridge limit volume is imposed to avoid extensive clustering of liquid. Studying the effect of the local shear rate on the liquid redistribution, two distinct effects are observed: For small amounts of shear, i.e., small strain amplitude, the interstitial liquid is randomly redistributed locally, and for larger amounts of shear, liquid is transported away from the shear zone. The local redistribution quickly results in a characteristic probability distribution of liquid bridge volumes, independent of the initial wetting conditions, but the mean and the shape of the distribution are dependent on the limit volume. Although the shear-driven diffusion-like liquid transport is active from the beginning, it dominates the transport in the long term, when the liquid moves out of the shear band, making the shear band dry. Ongoing theoretical analysis suggests a competition of drift and diffusive mechanisms in a different set of coordinates that can explain all our observations by defining a local Péclet number that quantifies the relative strength of the two transport mechanisms.

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Role of contact-angle hysteresis for fluid transport in wet granular matter

Cited by 18 publications

References 24 publications

Contact angle mechanical influence in wet granular soils

Contact angle mechanical influence in wet granular soils

Liquid morphologies and capillary forces between three spherical beads

Liquid redistribution in sheared wet granular media

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