scholarly journals Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

2010 ◽  
Vol 7 (2) ◽  
pp. 2997-3018 ◽  
Author(s):  
E. M. A. Perrier ◽  
N. R. A. Bird ◽  
T. B. Rieutord
Keyword(s):  
Pore Size ◽  
Scaling Laws ◽  
Fractal Dimensions ◽  
Natural Soil ◽  
Pore Networks ◽  
Multi Scale ◽  
Soil Ecosystems ◽  
Pore Size Distributions ◽  
Soil Structures ◽  
Soil Filtration

Abstract. Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a Critical Filtration Size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

scholarly journals Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

2010 ◽  
Vol 7 (10) ◽  
pp. 3177-3186 ◽  
Author(s):  
E. M. A. Perrier ◽  
N. R. A. Bird ◽  
T. B. Rieutord
Keyword(s):  
Pore Size ◽  
Scaling Laws ◽  
Fractal Dimensions ◽  
Natural Soil ◽  
Pore Networks ◽  
Multi Scale ◽  
Soil Ecosystems ◽  
Pore Size Distributions ◽  
Soil Structures ◽  
Soil Filtration

Abstract. Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a critical filtration size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

Study for Quantitative Analysis of Loess Microstructure Influence

2012 ◽  
Vol 594-597 ◽  
pp. 522-526
Author(s):  
Peng Ran Song ◽  
Chang Ming Wang
Keyword(s):  
Image Processing ◽  
Pore Size ◽  
Influence Factors ◽  
Fractal Dimensions ◽  
Engineering Properties ◽  
Size Distributions ◽  
Sem Images ◽  
Soil Microstructure ◽  
Computer Image Processing ◽  
Pore Size Distributions

Microstructure is a important index of soil physical, mechanical and engineering properties, SEM images and computer image processing technology make the soil microstructure research developing rapidly in recent years, but the researches on the influence factors and important degree are rare. Process the images form scanning electron microscopy test with the image processing toolbox of MATLAB. Fractal dimensions, porosities and pore size distributions are calculated in different analyzing windows, thresholds and magnifications. The results show that:1) As the results of the experiment influenced greatly by the smaller analyzing windows, in order to get the real calculation value, the medium section was processed; 2) Fractal dimension values are less influenced than porosities and pore size distributions by different thresholds; 3) Too big magnification can cause inaccurate fractal dimensions. Porosities and pore size distributions are inverse growing with increasing of magnification.

scholarly journals FRACTAL PARAMETERS OF PORE SPACE FROM CT IMAGES OF SOILS UNDER CONTRASTING MANAGEMENT PRACTICES

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440011 ◽  
Author(s):  
F. J. MUÑOZ ◽  
F. SAN JOSÉ MARTÍNEZ ◽  
F. J. CANIEGO
Keyword(s):  
Pore Size ◽  
Soil Structure ◽  
Management Practices ◽  
Pore Space ◽  
Fractal Dimensions ◽  
Soil Management ◽  
Ct Images ◽  
Pore Size Distributions ◽  
Fractal Parameters

Soil structure plays an important role in flow and transport phenomena, and a quantitative characterization of the spatial heterogeneity of the pore space geometry is beneficial for prediction of soil physical properties. Morphological features such as pore-size distribution, pore space volume or pore–solid surface can be altered by different soil management practices. Irregularity of these features and their changes can be described using fractal geometry. In this study, we focus primarily on the characterization of soil pore space as a 3D geometrical shape by fractal analysis and on the ability of fractal dimensions to differentiate between two a priori different soil structures. We analyze X-ray computed tomography (CT) images of soils samples from two nearby areas with contrasting management practices. Within these two different soil systems, samples were collected from three depths. Fractal dimensions of the pore-size distributions were different depending on soil use and averaged values also differed at each depth. Fractal dimensions of the volume and surface of the pore space were lower in the tilled soil than in the natural soil but their standard deviations were higher in the former as compared to the latter. Also, it was observed that soil use was a factor that had a statistically significant effect on fractal parameters. Fractal parameters provide useful complementary information about changes in soil structure due to changes in soil management.

scholarly journals Porous Alumina Ceramics with Multimodal Pore Size Distributions

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3294
Author(s):  
Jonas Biggemann ◽  
Martin Stumpf ◽  
Tobias Fey
Keyword(s):  
Thermal Properties ◽  
Pore Size ◽  
Porous Alumina ◽  
Laser Flash ◽  
Porous Ceramics ◽  
Mechanical And Thermal Properties ◽  
Size Distributions ◽  
Cell Size Distribution ◽  
Pore Networks ◽  
Pore Size Distributions

Pore networks with multimodal pore size distributions combining advantages from isotropic and anisotropic shaped pores of different sizes are highly attractive to optimize the physical properties of porous ceramics. Multimodal porous Al2O3 ceramics were manufactured using pyrolyzed cellulose fibers (l = 150 µm, d = 8 µm) and two types of isotropic phenolic resin spheres (d = 30 and 300 µm) as sacrificial templates. The sacrificial templates were homogeneously distributed in the Al2O3 matrix, compacted by uniaxial pressing and extracted by a burnout and sintering process up to 1700 °C in air. The amount of sacrificial templates was varied up to a volume content of 67 Vol% to form pore networks with porosities of 0–60 Vol%. The mechanical and thermal properties were measured by 4-point-bending and laser flash analysis (LFA) resulting in bending strengths of 173 MPa to 14 MPa and heat conductivities of 22.5 Wm−1K−1 to 4.6 Wm−1K−1. Based on µCT-measurements, the representative volume-of-interest (VOI) of the samples digital twin was determined for further analysis. The interconnectivity, tortuosity, permeability, the local and global stress distribution as well as strut and cell size distribution were evaluated on the digital twin’s VOI. Based on the experimental and simulation results, the samples pore network can be tailored by changing the fiber to sphere ratio and the overall sacrificial template volume. The presence pore formers significantly influenced the mechanical and thermal properties, resulting in higher strengths for samples containing fibrous templates and lower heat conductivities for samples containing spherical templates.

CHARACTERIZATION OF PORE SIZE DISTRIBUTIONS USING NON-NEWTONIAN FLUIDS

2020 ◽  
Author(s):  
Scott C. Hauswirth ◽  
◽  
Majdi Abou Najm ◽  
Christelle Basset
Keyword(s):  
Pore Size ◽  
Newtonian Fluids ◽  
Size Distributions ◽  
Pore Size Distributions

Preparation of P(GMA-co-EGDMA) Monolithic Columns with Adjustable Porous Properties

2014 ◽  
Vol 936 ◽  
pp. 942-949 ◽  
Author(s):  
Hao Tian Zhang ◽  
Qiu Yu Zhang ◽  
Bao Liang Zhang ◽  
Chun Mei Li
Keyword(s):  
Pore Size ◽  
Monolithic Column ◽  
Organic Polymer ◽  
Monolithic Columns ◽  
Size Distributions ◽  
Notable Effect ◽  
Pore Size Distributions ◽  
Porous Properties ◽  
Glass Tubes ◽  
First Time

Porous properties have notable effect on separating effect of organic polymer-based monolithic column. Different applications of monolithic columns require tailored pore size distributions. On account of that, P(GMA-co-EGDMA) monolithic columns were prepared with novel ternary porogenic agents. Glass tubes was chosen as polymerization mold. Moreover, factors influencing the inner pore morphology, pore size and specific surface area were investigated systematically. The results showed that the increasing of the solubility of porogenic agents and the amount of crosslinker, the decreasing of the amount of porogenic agents and temperature rising all could give rise to the decreasing of pore size. Remarkably, the effect of initiator was studied for the first time. The results showed that amount of initiator had no remarkable influence on porous properties. By controlling effect factors, P(GMA-co-EGDMA) Monolithic Columns with pore size from dozens to thousands of nanometer, which can be applied in separation of molecules with different size.

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