Abstract
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997)]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓ(a)/ℓ(b) less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.
Highlights
Swelling clay minerals are composed of an octahedral sheet sandwiched between two opposing tetrahedral sheets
The present study focuses on developing an alternative algorithm to obtain simulated 3D swelling clay porous media with the possibility of varying particle geometrical parameters and particle orientation
The results obtained for disks of different aspect ratios are consistent with published data
Summary
Swelling clay minerals (i.e., smectite and vermiculite) are composed of an octahedral sheet (with Al, Mg, Fe, etc.) sandwiched between two opposing tetrahedral sheets (with Si, Al, and Fe). A spatial resolution that allows for a wide range of porosities in pure swelling clay-based materials to be covered is still rather difficult to attain, especially for small pore sizes Another approach for examining porous media applicable to clay minerals lies in the use of 3D particle packing simulation procedures. The present study focuses on developing an alternative algorithm ( based on the sequential deposition procedure) to obtain simulated 3D swelling clay porous media with the possibility of varying particle geometrical parameters and particle orientation. The development of such an algorithm is motivated by our recent experimental studies, which focused on model systems with tunable particle orientation that provide materials with varying degrees of anisotropy [32]. We first compare the surface and geometric properties of the obtained virtual packings with experimental data and explore the properties of the obtained virtual porous media to extract useful stereological information regarding the pores and the solid phase
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