scholarly journals Micro- and macro-scale water retention properties of granular soils: contribution of the X-Ray CT-based voxel percolation method

Soil Research ◽  
2019 ◽  
Vol 57 (6) ◽  
pp. 575
Author(s):  
Erika Shiota ◽  
Toshifumi Mukunoki ◽  
Laurent Oxarango ◽  
Anne-Julie Tinet ◽  
Fabrice Golfier
Keyword(s):  
Water Retention ◽  
Drainage Water ◽  
Transport Processes ◽  
Water Retention Curve ◽  
Granular Soils ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Percolation Method ◽  
Macro Scale

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.

Geochemical controls on wettability alteration at pore-scale during low salinity water flooding in sandstone using X-ray micro computed tomography

Fuel ◽  
2020 ◽  
Vol 271 ◽  
pp. 117675 ◽  
Author(s):  
Yongqiang Chen ◽  
Nilesh Kumar Jha ◽  
Duraid Al-Bayati ◽  
Maxim Lebedev ◽  
Mohammad Sarmadivaleh ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Water Flooding ◽  
Wettability Alteration ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Geochemical Controls ◽  
Salinity Water

scholarly journals 4D imaging of sub-second dynamics in pore-scale processes using real time synchrotron x-ray tomography

2016 ◽  
Author(s):  
Katherine J. Dobson ◽  
Sophia B. Coban ◽  
Sam A. McDonald ◽  
Joanna Walsh ◽  
Robert Atwood ◽  
...  
Keyword(s):  
Real Time ◽  
High Frequency ◽  
High Speed ◽  
Motion Blur ◽  
Transport Processes ◽  
Fluid Distribution ◽  
Pore Scale ◽  
X Ray ◽  
Wide Range ◽  
In Situ Experiments

Abstract. A variable volume flow cell has been integrated with state-of-the-art ultra-high speed synchrotron x-ray tomography imaging. The combination allows the first real time (sub-second) capture of dynamic pore (micron) scale fluid transport processes in 4D (3D + time). With 3D data volumes acquired at up to 20 Hz, we perform in situ experiments that capture high frequency pore-scale dynamics in 5–25 mm diameter samples with voxel (3D equivalent of a pixel) resolution of 2.5 to 3.8 µm. The data are free from motion artefacts, can be spatially registered or collected in the same orientation making them suitable for detailed quantitative analysis of the dynamic fluid distribution pathways and processes. The method presented here are capable of capturing a wide range of high frequency non equilibrium pore-scale processed including wetting, dilution, mixing and reaction phenomena, without sacrificing significant spatial resolution. As well as fast streaming (continuous acquisition) at 20 Hz, it also allows larger-scale and longer term experimental runs to be sampled intermittently at lower frequency (time-lapse imaging); benefiting from fast image acquisition rates to prevent motion blur in highly dynamic systems. This marks a major technical breakthrough for quantification of high frequency pore scale processes: processes that are critical for developing and validating more accurate multiscale flow models through spatially and temporally heterogeneous pore networks.

Micro-Computed Tomography Pore-Scale Study on Natural Convection in a Cubic Cavity Filled With Complex Porous Medium

2020 ◽  
Author(s):  
Xu Wang ◽  
Peng Li ◽  
Anyi Xu ◽  
Zhenyu Liu
Keyword(s):  
Computed Tomography ◽  
Porous Medium ◽  
Natural Convection ◽  
Porous Structure ◽  
Transport Processes ◽  
Scale Model ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
Small Pore ◽  
Porous Domain

Abstract A pore-scale numerical simulation was carried out in this study to predict the natural convection in a cubic cavity filled with reconstructed porous medium using lattice Boltzmann Method (LBM). The computational porous domain was established with the micro-computed tomography technique. The natural convection phenomena were predicted with the pore-scale simulation for different thermal boundary conditions and fluid thermal properties. The results show that the natural convection in the present porous domain is more obvious as the side wall is heated compared to that as the bottom wall is heated. The existence of porous structure suppresses the natural convection in the cubic cavity. As Rayleigh number increases, the natural convection in the porous domain is enhanced accordingly. The heat flux distribution on the porous structure surface varies intensively due to the complex flow characteristic in the small pore spaces. The numerical approach presented in this study is to provide a promising solution that can simulate pore-scale natural convection in porous medium and can be further extended for the development of field-scale model for transport processes in porous medium.

scholarly journals Application of single-board computers in experimental research on unsaturated soils

2020 ◽  
Vol 195 ◽  
pp. 02022
Author(s):  
Marius Milatz
Keyword(s):  
Uniaxial Compression ◽  
Mechanical Behaviour ◽  
Unsaturated Soils ◽  
Water Retention ◽  
University Teaching ◽  
Water Retention Curve ◽  
Raspberry Pi ◽  
Granular Soils ◽  
Compression Tests ◽  
Unsaturated Granular Soils

In this contribution, the application of single-board computers for the investigation of the hydro-mechanical behaviour of unsaturated granular soils is presented. Single-board computers, such as the Raspberry Pi or Arduino, have recently experienced a hype of applications in school and university teaching, in the maker scene, amongst hobbyists, but also in research. In combination with easy to learn and open programming languages, such as Python, individual experimental set-ups for research in unsaturated soil mechanics, using actuators and sensors can be easily developed with the help of different programmable hardware, such as stepper motors, analog-to-digital converters and other controller boards. For the experimental application in imaging of unsaturated granular soils by computed tomography (CT), we present a miniaturized uniaxial compression device for the measurement of unsaturated shear strength and capillary cohesion in CT-experiments. The device has already been applied for CT-imaging of the development of water distribution and capillary bridges in between different shear steps. Furthermore, a new fully programmable hydraulic experimental set-up for the automated investigation of transient hydraulic paths of the water retention curve of granular media is presented. Both devices have been developed in the framework of the Raspberry Pi single-board computer and Python programming language with simple and relatively inexpensive hardware components. In addition to the technical development of the testing devices, experimental results of the hydro-mechanical behaviour of unsaturated sand and glass beads, derived from uniaxial compression tests and water retention tests, will be presented.

Predicting Hysteresis of the Water Retention Curve from Basic Properties of Granular Soils

2012 ◽  
Vol 30 (5) ◽  
pp. 1147-1159 ◽  
Author(s):  
Abdelkabir Maqsoud ◽  
Bruno Bussière ◽  
Michel Aubertin ◽  
Mamert Mbonimpa
Keyword(s):  
Water Retention ◽  
Water Retention Curve ◽  
Granular Soils ◽  
Retention Curve ◽  
Basic Properties

scholarly journals 4-D imaging of sub-second dynamics in pore-scale processes using real-time synchrotron X-ray tomography

Solid Earth ◽  
2016 ◽  
Vol 7 (4) ◽  
pp. 1059-1073 ◽  
Author(s):  
Katherine J. Dobson ◽  
Sophia B. Coban ◽  
Samuel A. McDonald ◽  
Joanna N. Walsh ◽  
Robert C. Atwood ◽  
...  
Keyword(s):  
Real Time ◽  
High Frequency ◽  
High Speed ◽  
Motion Blur ◽  
Transport Processes ◽  
Fluid Distribution ◽  
Pore Scale ◽  
X Ray ◽  
Wide Range ◽  
In Situ Experiments

Abstract. A variable volume flow cell has been integrated with state-of-the-art ultra-high-speed synchrotron X-ray tomography imaging. The combination allows the first real-time (sub-second) capture of dynamic pore (micron)-scale fluid transport processes in 4-D (3-D + time). With 3-D data volumes acquired at up to 20 Hz, we perform in situ experiments that capture high-frequency pore-scale dynamics in 5–25 mm diameter samples with voxel (3-D equivalent of a pixel) resolutions of 2.5 to 3.8 µm. The data are free from motion artefacts and can be spatially registered or collected in the same orientation, making them suitable for detailed quantitative analysis of the dynamic fluid distribution pathways and processes. The methods presented here are capable of capturing a wide range of high-frequency nonequilibrium pore-scale processes including wetting, dilution, mixing, and reaction phenomena, without sacrificing significant spatial resolution. As well as fast streaming (continuous acquisition) at 20 Hz, they also allow larger-scale and longer-term experimental runs to be sampled intermittently at lower frequency (time-lapse imaging), benefiting from fast image acquisition rates to prevent motion blur in highly dynamic systems. This marks a major technical breakthrough for quantification of high-frequency pore-scale processes: processes that are critical for developing and validating more accurate multiscale flow models through spatially and temporally heterogeneous pore networks.

scholarly journals Fast micro-computed tomography data of solute transport in porous media with different heterogeneity levels

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Stefanie Van Offenwert ◽  
Veerle Cnudde ◽  
Marijn Boone ◽  
Tom Bultreys
Keyword(s):  
Computed Tomography ◽  
Solute Transport ◽  
Temporal Resolution ◽  
Solute Concentration ◽  
Transport Processes ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
Tracer Injection ◽  
Voxel Size ◽  
Scale Heterogeneity

AbstractSolute transport processes are influenced by pore-scale heterogeneity. To study this, transient micron-scale solute concentration fields were imaged by fast laboratory-based X-ray micro-computed tomography. We performed tracer injection experiments in three types of porous material with increasing levels of heterogeneity (sintered glass, Bentheimer sandstone and Savonnières limestone). Different Peclet numbers were used during the experiments. For each sample and Peclet number, datasets of 40 to 74 3D images were acquired by continuous scanning with a voxel size of 13.4 to 14.6 µm and a temporal resolution of 15 to 12 seconds. To determine the measurement uncertainty on the obtained concentration fields, we performed calibration experiments under similar circumstances (temporal resolution of 12 seconds and voxel size of 13.0 µm). Here, we provide a systematic description of the data acquisition and processing and make all data, a total of 464 tomograms, publicly available. The combined dataset offers new opportunities to study the influence of pore-scale heterogeneity on solute transport, and to validate pore-scale simulations of this process in increasingly complex samples.

Experimental pore-scale analysis of carbon dioxide hydrate in sandstone via X-Ray micro-computed tomography

2018 ◽  
Vol 79 ◽  
pp. 73-82 ◽  
Author(s):  
Dhifaf Sadeq ◽  
Stefan Iglauer ◽  
Maxim Lebedev ◽  
Taufiq Rahman ◽  
Yihuai Zhang ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Carbon Dioxide ◽  
Scale Analysis ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Carbon Dioxide Hydrate
Sign in / Sign up

Export Citation Format

Share Document