Wetting front instability in unsaturated porous media: A three-dimensional study in initially dry sand

1990 ◽  
Vol 5 (3) ◽  
pp. 247-268 ◽  
Author(s):  
Robert J. Glass ◽  
Steve Cann ◽  
Jeff King ◽  
Nathan Baily ◽  
J-Yves Parlange ◽  
...  
Keyword(s):  
Porous Media ◽  
Three Dimensional ◽  
Unsaturated Porous Media ◽  
Wetting Front ◽  
Front Instability ◽  
Dry Sand

Using MicroCT to Visualize Nanofluid Droplet Sorption Profiles in Unsaturated Porous Media

2016 ◽  
Author(s):  
Timothy Munuhe ◽  
Alexander LeBrun ◽  
Liang Zhu ◽  
Ronghui Ma
Keyword(s):  
Porous Media ◽  
Liquid Droplet ◽  
Water Evaporation ◽  
Unsaturated Porous Media ◽  
Important Process ◽  
Wetting Front ◽  
Gray Scale ◽  
Powder Bed ◽  
Wide Range ◽  
Pmma Powder

Liquid droplet sorption in unsaturated porous media is an important process for a wide range of applications. However, visualizing droplet sorption is difficult due to the opaque nature of porous media used in most of the applications. In this study, microCT is used to characterize the sorption profiles of single/multiple nanofuid droplets in PMMA powder beds. The microCT scan results reveal that the region of the powder bed saturated with nanofluid has a substantially higher gray scale value than that in the unsaturated region, thus enabling the visualization of the sorption profile. It also shows that nanoparticles enhance the visualization of the sorption profiles as they tend to accumulate and stay near the wetting front even after water evaporation.

Contaminant migration in unsaturated porous media using X-ray computerized tomography (CT)

2013 ◽  
Vol 69 (5) ◽  
pp. 953-959 ◽  
Author(s):  
Nian Qing Zhou ◽  
Shan Zhao ◽  
Wei Song ◽  
Jun Otani
Keyword(s):  
Porous Media ◽  
Computerized Tomography ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Silica Sand ◽  
Unsaturated Porous Media ◽  
Contaminant Migration ◽  
X Ray ◽  
Before And After ◽  
Unsaturated Zones

Landfills are usually located in unsaturated zones. Contaminant leaking can easily infiltrate groundwater through these porous media and contribute to groundwater pollution. The main objective of this work is to study the leachate migration in unsaturated porous media using X-ray computerized tomography (CT) and image-processing software. Silica sand and Yamazuna sand (collected from Japan) with different particle sizes are considered. Potassium iodide (KI) solution is used as a contaminant and injected into sand specimens at appropriate rates. The specimens are scanned at each cross section before and after contaminant injection by X-ray CT. Subsequently, all CT images are transformed into mean CT values by Image J software. VGStudio software is then used to reconstruct the subtracted images into three-dimensional images. The results indicate that vertical migration is dominant in uniform sand and horizontal migration is the main behavior in well-graded sand. Meanwhile, it is also confirmed that CT scanning is an effective technology to study contaminant migration in unsaturated porous media with different grain sizes.

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