Water retention and diffusion in unsaturated clays: Connecting atomistic and pore scale simulations

Water retention in granular soils is a key mechanism for understanding transport processes in the vadose zone for various applications from agronomy to hydrological and environmental sciences. The macroscopic pattern of water entrapment is mainly driven by the pore-scale morphology and capillary and gravity forces. In the present study, the drainage water retention curve (WRC) was measured for three different granular materials using a miniaturised hanging column apparatus. The samples were scanned using X-ray micro-computed tomography during the experiment. A segmentation procedure was applied to identify air, water and solid phases in 3D at the pore-scale. A representative elementary volume analysis based on volume and surface properties validated the experimental setup size. A morphological approach, the voxel percolation method (VPM) was used to model the drainage experiment under the assumption of capillary-dominated quasi-static flow. At the macro-scale, the VPM showed a good capability to predict the WRC when compared with direct experimental measurements. An in-depth comparison with image data also revealed a satisfactory agreement concerning both the average volumetric distributions and the pore-scale local topology. Image voxelisation and the quasi-static assumption of VPM are likely to explain minor discrepancies observed at low suctions and for coarser materials.

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Laboratory study of cryogenic treatment induced pore-scale structural alterations of Illinois coal and their implications on gas sorption and diffusion behaviors

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2020.107507 ◽

2020 ◽

Vol 194 ◽

pp. 107507 ◽

Cited By ~ 1

Author(s):

Yun Yang ◽

Shimin Liu

Keyword(s):

Laboratory Study ◽

Cryogenic Treatment ◽

Pore Scale ◽

Gas Sorption ◽

Structural Alterations ◽

And Diffusion ◽

Diffusion Behaviors

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Prediction of relative and absolute permeabilities for gas and water from soil water retention curves using a pore-scale network model

Water Resources Research ◽

10.1029/1998wr900048 ◽

1999 ◽

Vol 35 (4) ◽

pp. 1089-1100 ◽

Cited By ~ 59

Author(s):

Ulrich Fischer ◽

Michael A. Celia

Keyword(s):

Soil Water ◽

Network Model ◽

Water Retention ◽

Pore Scale ◽

Soil Water Retention ◽

Scale Network ◽

Pore Scale Network

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Pore-Scale Model for Water Retention and Fluid Partitioning of Partially Saturated Granular Soil

Journal of Geotechnical and Geoenvironmental Engineering ◽

10.1061/(asce)gt.1943-5606.0000811 ◽

2013 ◽

Vol 139 (5) ◽

pp. 724-737 ◽

Cited By ~ 42

Author(s):

William J. Likos ◽

Rani Jaafar

Keyword(s):

Water Retention ◽

Scale Model ◽

Granular Soil ◽

Pore Scale ◽

Partially Saturated ◽

Pore Scale Model

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Pore Scale Study of Methane Advection and Diffusion in Image-Based 3-D Reconstruction of Shale with Consideration of Bound Water

Proceedings of the 8th Unconventional Resources Technology Conference ◽

10.15530/urtec-2020-3254 ◽

2020 ◽

Author(s):

Rui Xu ◽

Ying Yin ◽

Christopher Landry ◽

Maša Prodanović

Keyword(s):

Bound Water ◽

Pore Scale ◽

And Diffusion

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Meridional Circulation, Turbulence, and Diffusion Processes in Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100080477 ◽

1976 ◽

Vol 32 ◽

pp. 109-116 ◽

Cited By ~ 1

Author(s):

S. Vauclair

Keyword(s):

Convection Zone ◽

Diffusion Processes ◽

Meridional Circulation ◽

Diffusion Time ◽

Work In Progress ◽

First Results ◽

Stellar Envelopes ◽

And Diffusion ◽

Turbulence And Diffusion ◽

Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

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