Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/20386
Title: A multi-scale Lattice Boltzmann model for simulating solute transport in 3D X-ray micro-tomography images of aggregated porous materials
Contributor(s): Zhang, Xiaoxian (author); Crawford, John W (author); Flavel, Richard  (author)orcid ; Young, Iain  (author)
Publication Date: 2016
DOI: 10.1016/j.jhydrol.2016.08.013
Handle Link: https://hdl.handle.net/1959.11/20386
Abstract: The Lattice Boltzmann (LB) model and X-ray computed tomography (CT) have been increasingly used in combination over the past decade to simulate water flow and chemical transport at pore scale in porous materials. Because of its limitation in resolution and the hierarchical structure of most natural soils, the X-ray CT tomography can only identify pores that are greater than its resolution and treats other pores as solid. As a result, the so-called solid phase in X-ray images may in reality be a grey phase, containing substantial connected pores capable of conducing fluids and solute. Although modified LB models have been developed to simulate fluid flow in such media, models for solute transport are relatively limited. In this paper, we propose a LB model for simulating solute transport in binary soil images containing permeable solid phase. The model is based on the single-relaxation time approach and uses a modified partial bounce-back method to describe the resistance caused by the permeable solid phase to chemical transport. We derive the relationship between the diffusion coefficient and the parameter introduced in the partial bounce-back method, and test the model against analytical solution for movement of a pulse of tracer. We also validate it against classical finite volume method for solute diffusion in a simple 2D image, and then apply the model to a soil image acquired using X-ray tomography at resolution of 30 μm in attempts to analyse how the ability of the solid phase to diffuse solute at micron-scale affects the behaviour of the solute at macro-scale after a volumetric average. Based on the simulated results, we discuss briefly the danger in interpreting experimental results using the continuum model without fully understanding the pore-scale processes, as well as the potential of using pore-scale modelling and tomography to help improve the continuum models.
Publication Type: Journal Article
Source of Publication: Journal of Hydrology, 541(Part B), p. 1020-1029
Publisher: Elsevier BV
Place of Publication: Netherlands
ISSN: 0022-1694
Fields of Research (FoR) 2008: 070399 Crop and Pasture Production not elsewhere classified
050305 Soil Physics
Fields of Research (FoR) 2020: 410605 Soil physics
Socio-Economic Objective (SEO) 2008: 961402 Farmland, Arable Cropland and Permanent Cropland Soils
970107 Expanding Knowledge in the Agricultural and Veterinary Sciences
Socio-Economic Objective (SEO) 2020: 180605 Soils
280101 Expanding knowledge in the agricultural, food and veterinary sciences
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article

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