The strength of liquid bridges in random granular materials

Grof, Zdeněk; Lawrence, C.J.; Štěpánek, František

doi:10.1016/j.jcis.2007.11.055

Cited by 27 publications

(26 citation statements)

References 16 publications

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“…Darabi et al, presented a new coalescence model for binary collision between two identical wet particles, considering capillary and viscous forces exerted by (instantaneously formed) pendular bridges. Despite a variety of researchers that has broadened our understanding of liquid bridges, a study describing a detailed model on the time evolution of a single (pendular) liquid bridge during its formation phase is still missing. This is due to the lack of our understanding how quickly liquid is transported into a liquid bridge, and how much of the liquid (initially present on the particles) is able to flow into the bridge.…”

Section: Introductionmentioning

confidence: 99%

A model to predict liquid bridge formation between wet particles based on direct numerical simulations

Radl

Khinast

2016

AIChE Journal

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We study dynamic liquid bridge formation, which is relevant for wet granular flows involving highly viscous liquids and short collisions. Specifically, the drainage process of liquid adhering to two identical, non-porous wet particles with different initial film heights is simulated using Direct Numerical Simulations (DNS). We extract the position of the interface, and define the liquid bridge and its volume by detecting a characteristic neck position. This allows us building a dynamic model for predicting bridge volume, and the liquid remaining on the particle surface. Our model is based on two dimensionless mobility parameters, as well as a dimensionless time scale to describe the filling process. In the present work model parameters were calibrated with DNS data. We find that the proposed model structure is sufficient to collapse all our simulation data, indicating that our model is general enough to describe liquid bridge formation between equally sized particles.

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Section: Introductionmentioning

confidence: 99%

A model to predict liquid bridge formation between wet particles based on direct numerical simulations

Radl

Khinast

2016

AIChE Journal

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“…The bridge volume and the wetting properties of the solid surfaces then determine the shape of the liquid bridge and the capillary pressure. In this case the volume of the liquid bridge acts as a controlling parameter and determines the capillary forces [10,42].…”

Section: Introductionmentioning

confidence: 99%

Capillary adhesion at the nanometer scale

Cheng

Robbins

2014

Phys. Rev. E

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Molecular dynamics simulations are used to study the capillary adhesion from a nonvolatile liquid meniscus between a spherical tip and a flat substrate. The atomic structure of the tip, the tip radius, the contact angles of the liquid on the two surfaces, and the volume of the liquid bridge are varied. The capillary force between the tip and substrate is calculated as a function of their separation h. The force agrees with continuum predictions based on macroscopic theory for h down to ∼5 to 10 nm. At smaller h, the force tends to be less attractive than predicted and has strong oscillations. This oscillatory component of the capillary force is completely missed in the macroscopic theory, which only includes contributions from the surface tension around the circumference of the meniscus and the pressure difference over the cross section of the meniscus. The oscillation is found to be due to molecular layering of the liquid confined in the narrow gap between the tip and substrate. This effect is most pronounced for large tip radii and/or smooth surfaces. The other two components considered by the macroscopic theory are also identified. The surface tension term, as well as the meniscus shape, is accurately described by the macroscopic theory for h down to ∼1 nm, but the capillary pressure term is always more positive than the corresponding continuum result. This shift in the capillary pressure reduces the average adhesion by a factor as large as 2 from its continuum value and is found to be due to an anisotropy in the pressure tensor. The component in the plane of the substrate is consistent with the capillary pressure predicted by the macroscopic theory (i.e., the Young-Laplace equation), but the normal pressure that determines the capillary force is always more positive than the continuum counterpart.

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“…The interfacial geometries that separate phases are often complicated and are dictated by intermolecular forces, pore structure, pressure and temperature [e.g., Israelachvili , 1992]. At the pore scale, analytical techniques are generally confined to solutions of the Laplace‐Young equation for idealized particle geometries such as spheres or disks [e.g., Fisher , 1926; Mason and Clark , 1965; Orr et al , 1975; Pierrat and Caram , 1997; Richefeu et al , 2006; Grof et al , 2008; Lechman and Lu , 2008]. While such solutions give important physical insights, the need remains for a methodology to address more complicated pore geometries such as in soils [e.g., Hornbaker et al , 1997].…”

Section: Introductionmentioning

confidence: 99%

“…Along another path, computational fluid dynamics and lattice gas automata methods have been used to compute the pore‐scale geometrical evolution of liquid bodies in porous media with complex pore geometries, but with the computational overhead of capturing the transport behaviour [ Rothman and Zaleski , 1994]. There has also recently been a coarse‐grained approach based on direct discretized simulation of the liquid‐vapor interface, although this introduces complications associated with the merging and breakup of liquid domains [ Grof et al , 2008]. To address the need for an efficient pore‐scale simulation methodology and overcome some of the aforementioned deficiencies in the previous simulation methods, we developed a coarse‐grained Monte Carlo lattice gas approach.…”

Section: Introductionmentioning

confidence: 99%

A Monte Carlo paradigm for capillarity in porous media

Zeidman

Lusk

et al. 2010

Geophysical Research Letters

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[1] Wet porous media are ubiquitous in nature as soils, rocks, plants, and bones, and in engineering settings such as oil production, ground stability, filtration and composites. Their physical and chemical behavior is governed by the distribution of liquid and interfaces between phases. Characterization of the interfacial distribution is mostly based on macroscopic experiments, aided by empirical formulae. We present an alternative computational paradigm utilizing a Monte Carlo algorithm to simulate interfaces in complex realistic pore geometries. The method agrees with analytical solutions available only for idealized pore geometries, and is in quantitative agreement with Micro X-ray Computed Tomography (microXCT), capillary pressure, and interfacial area measurements for natural soils. We demonstrate that this methodology predicts macroscopic properties such as the capillary pressure and air-liquid interface area versus liquid saturation based only on the pore size information from microXCT images and interfacial interaction energies. The generality of this method should allow simulation of capillarity in many porous materials. Citation:

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The strength of liquid bridges in random granular materials

Cited by 27 publications

References 16 publications

A model to predict liquid bridge formation between wet particles based on direct numerical simulations

A model to predict liquid bridge formation between wet particles based on direct numerical simulations

Capillary adhesion at the nanometer scale

A Monte Carlo paradigm for capillarity in porous media

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