High-Resolution Neutron and X-Ray Imaging of Granular Materials

Kim, Felix H.; Penumadu, Dayakar; Gregor, Jens; Kardjilov, Nikolay; Manke, Ingo

doi:10.1061/(asce)gt.1943-5606.0000809

Cited by 65 publications

(35 citation statements)

References 45 publications

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“…Although XCT scanning is useful for reconstructing speleothem structure given the sensitivity of X-rays to the mineral calcite, X-rays are not sensitive to hydrogen (Schwarz et al, 2005;Tumlison et al, 2007;Wilding et al, 2005). Conversely, neutron computed tomography (NCT) scanning, with a resolution as high as 10 μm, has the potential to distinguish in a stalagmite between regions of dominantly liquid-versus airfilled inclusions given the high thermal neutron attenuation by hydrogen and the ability of neutrons to penetrate through denser materials (Kim et al, 2013;Schwarz et al, 2005;Tumlison et al, 2007;Wilding et al, 2005). Conversely, neutron computed tomography (NCT) scanning, with a resolution as high as 10 μm, has the potential to distinguish in a stalagmite between regions of dominantly liquid-versus airfilled inclusions given the high thermal neutron attenuation by hydrogen and the ability of neutrons to penetrate through denser materials (Kim et al, 2013;Schwarz et al, 2005;Tumlison et al, 2007;Wilding et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Mapping Fluid‐Filled Inclusions in Stalagmites Using Coupled X‐Ray and Neutron Computed Tomography: Potential as a Water Excess Proxy

Wortham

Montañez

Rowland

et al. 2019

Geochem Geophys Geosyst

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Application of novel proxies, such as the stable isotope compositions and noble gas concentrations of fossil drip water trapped as inclusions in stalagmites, have the potential to provide unique constraints on past hydroclimate states and surface temperatures. Geochemical analysis of inclusion waters, however, requires an understanding of the three‐dimensional spatial distribution of dominantly liquid‐ versus air‐filled inclusions in a given stalagmite. Here we couple neutron computed tomography and medium‐ to high‐resolution X‐ray computed tomography to map out the three‐dimensional calcite density and distribution of liquid‐ versus air‐filled inclusions within a Sierra Nevada stalagmite (ML‐1), which formed during the last deglaciation (18.5 to 11.7 ka). Comparison of coupled neutron computed tomography‐X‐ray computed tomography results with a time series of stalagmite calcite fabrics indicates that although highest density calcite contains abundant liquid (fluid)‐filled inclusions, calcite density and fabric overall were secondary controls on the liquid inclusion distribution (LID). Furthermore, a multistatistical evaluation of the stalagmite time series indicates a significant relationship at the multicentury‐ to millennial‐scale between LID and calcite δ18O and δ13C that suggests a potential link between LID and water availability to the cave.

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Section: Introductionmentioning

confidence: 99%

Mapping Fluid‐Filled Inclusions in Stalagmites Using Coupled X‐Ray and Neutron Computed Tomography: Potential as a Water Excess Proxy

Wortham

Montañez

Rowland

et al. 2019

Geochem Geophys Geosyst

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“…The observations and quantitative evaluations of the developed algorithms are presented in this section. The void ratio is often used to characterise the assembly and it is defined as

e = \frac{V_{v}}{V_{s}} = \frac{V_{tot} - V_{s}}{V_{s}} = \frac{V_{tot}}{V_{s}} - 1 = \frac{1}{ρ} - 1

where V v is the volume of voids, V s is the volume of solid, V t o t is the total volume of the assembly and ρ is the packing density. The void ratio can vary inside each single assembly, and additionally, it is strongly affected by the presence of the walls and of the free surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…The observations and quantitative evaluations of the developed algorithms are presented in this section. The void ratio is often used to characterise the assembly [38,39] and it is defined as…”

Section: Resultsmentioning

confidence: 99%

New 3D geometrical deposition methods for efficient packing of spheres based on tangency

Cola

Falco

Barbieri

et al. 2015

Numerical Meth Engineering

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SUMMARYThe morphology of many natural and man-made materials at different length scales can be simulated using particle-packing methods. This paper presents two novel 3D geometrical collective deposition algorithms for packed assemblies with prescribed distribution of radii: the 'planar deposition' and the '3D-clew' method. The 'planar deposition' method mimics an orderly granular flow through a funnel by stacking up spirally ordinated planar assemblies of spheres capable of achieving the theoretical maximum for monodisperse aggregates. The '3D-clew' method, instead, mimics the winding of a clew of yarn, thus yielding densely packed 3D polydispersed assemblies in terms of void ratio of the aggregate. The morphologies of such geometrically generated assemblies, achieved at several orders of magnitude reduced computational cost, are comparable with those consolidated uni-directionally by means of discrete element method. In addition, significantly faster simulations of mechanical consolidation of granular media have been performed when relying upon the proposed geometrically generated assemblies as starting configurations.

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“…Kim et al . () presented a study showing the value of an X‐ray CT imaging tool to distinguish two fluid phases and a static sand, to then characterize pore‐scale features related to the fluids and solid structures. Different studies have used X‐ray CT to determine the fluid spatial distribution in rock samples (Karpyn et al .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, experimental techniques such as X-ray CT scanning have provided high-resolution, three-dimensional images of porous media under multiphase flow conditions. Kim et al (2013) presented a study showing the value of an X-ray CT imaging tool to distinguish two fluid phases and a static sand, to then characterize pore-scale features related to the fluids and solid structures. Different studies have used X-ray CT to determine the fluid spatial distribution in rock samples (Karpyn et al 2006;Prodanovic et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Pore‐scale investigation on stress‐dependent characteristics of granular packs and the impact of pore deformation on fluid distribution

et al. 2015

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Understanding the effect of changing stress conditions on multiphase flow in porous media is of fundamental importance for many subsurface activities including enhanced oil recovery, water drawdown from aquifers, soil confinement, and geologic carbon storage. Geomechanical properties of complex porous systems are dynamically linked to flow conditions, but their feedback relationship is often oversimplified due to the difficulty of representing pore-scale stress deformation and multiphase flow characteristics in high fidelity. In this work, we performed pore-scale experiments of single-and multiphase flow through bead packs at different confining pressure conditions to elucidate compaction-dependent characteristics of granular packs and their impact on fluid flow. A series of drainage and imbibition cycles were conducted on a water-wet, soda-lime glass bead pack under varying confining stress conditions. Simultaneously, X-ray micro-CT was used to visualize and quantify the degree of deformation and fluid distribution corresponding with each stress condition and injection cycle. Micro-CT images were segmented using a gradient-based method to identify fluids (e.g., oil and water), and solid phase redistribution throughout the different experimental stages. Changes in porosity, tortuosity, and specific surface area were quantified as a function of applied confining pressure. Results demonstrate varying degrees of sensitivity of these properties to confining pressure, which suggests that caution must be taken when considering scalability of these properties for practical modeling purposes. Changes in capillary number with confining pressure are attributed to the increase in pore velocity as a result of pore contraction. However, this increase in pore velocity was found to have a marginal impact on average phase trapping at different confining pressures.

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High-Resolution Neutron and X-Ray Imaging of Granular Materials

Cited by 65 publications

References 45 publications

Mapping Fluid‐Filled Inclusions in Stalagmites Using Coupled X‐Ray and Neutron Computed Tomography: Potential as a Water Excess Proxy

Mapping Fluid‐Filled Inclusions in Stalagmites Using Coupled X‐Ray and Neutron Computed Tomography: Potential as a Water Excess Proxy

New 3D geometrical deposition methods for efficient packing of spheres based on tangency

Pore‐scale investigation on stress‐dependent characteristics of granular packs and the impact of pore deformation on fluid distribution

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