Methodology for Optical Imaging of NAPL 3D Distribution in Transparent Porous Media

Kashuk, Sina; Mercurio, Sophia R.; Iskander, Magued

doi:10.1520/gtj20140153

Cited by 17 publications

(7 citation statements)

References 54 publications

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“…The use of transparent porous media allows relatively inexpensive measurements to be made at high spatial and temporal resolutions for greater sample depths than are possible using light reflection or transmission techniques. In some applications, transparent porous media also allow the reconstruction of three‐dimensional behavior using laser scanning (Ovdat and Berkowitz, 2006; Kong et al, 2011) or multiple cameras (Kashuk et al, 2015).…”

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confidence: 99%

Quantification of Fluid Saturations in Transparent Porous Media

Sills

Mumford

Siemens

2017

Vadose Zone Journal

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Core Ideas Imaging techniques are powerful for investigating multiphase flow in porous media. Transparent porous media can be used to quantify local fluid saturations. Efficient methods to calibrate intensity–saturation relationships are required. Our new procedure uses fewer images and measurements. Predicted saturations based on calibrated images matched independent measurements. Experiments using transparent porous media, where the indices of refraction of the solid grains and the wetting fluid are matched, can be used to quantify fluid saturations from digital images. In this study, significantly more efficient calibration and validation methods for unsaturated transparent porous media were developed, which used just three images and one saturation measurement. Imbibition and drainage column experiments were used to define the pixel intensity and saturation at residual wetting fluid saturation, as well as at residual nonwetting fluid saturation in two gradations of transparent porous media used for validation. The other images were pixel intensity at 100 and 0% wetting fluid saturation. Results from the drainage and imbibition experiments on the two transparent porous media gradations showed a log‐linear saturation–pixel intensity relationship, which agreed with the validation points from this study as well as those using a previous calibration method. We expect that this new calibration procedure will allow efficient development of saturation–pixel intensity relationships for the investigation of multiphase flow using transparent porous media under a variety of conditions.

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confidence: 99%

Quantification of Fluid Saturations in Transparent Porous Media

Sills

Mumford

Siemens

2017

Vadose Zone Journal

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“…In NAPL migration studies, the non-wetting phase (i.e., DNAPL) is typically colorized. Prominent examples of relevant dyes in the visible light spectrum are Oil-Red-O, Sudan Blue, Sudan III, and Sudan IV [33][34][35][36][37][38][39][40]53,54]. Such dyes are commonly used for semi-transparent porous media, such as glass beads, due to the good contrast ratio between porous media with water and with dyed DNAPL.…”

Section: General Considerations For Optical Imagingmentioning

confidence: 99%

“…They can be used to detect incoming ultraviolet, infrared and/or visible light, and are economically and technically more accessible. Optical imaging methods have been used by many researchers to investigate processes, such as groundwater flow and solute visualization (e.g., [21,22]), structure monitoring (e.g., [23]), saltwater intrusion (e.g., [24][25][26][27]), and NAPL migration (e.g., References [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. However, they also suffer from calibration and interpretation uncertainties, and more structured methods are needed for uniform interpretation.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Uncertainties from Image Processing and Analysis in Laboratory-Scale DNAPL Release Studies Evaluated by Reflective Optical Imaging

Engelmann

Schmidt

Werth

et al. 2019

Water

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Subsurface DNAPL (dense non-aqueous phase liquid) contamination from (un-) intentional spilling typically leads to severe environmental hazards. A large number of studies have demonstrated the relevance of DNAPL source zone geometry for the determination of contaminant plume propagation in groundwater. Optical imaging represents a promising non-invasive method for identifying DNAPL saturation without disturbing multiphase flow dynamics. However, workflow and image analysis methodologies have not been sufficiently developed or described for general application to related experimental efforts. For example, the choice of dye(s) used for phase colorization affects image processing and can bias final estimations of DNAPL saturations. In this study, we perform a series of DNAPL migration and entrapment studies in transparent tanks that are filled with three different types of porous media. Different dyes are used and raw images are acquired. Subsequently, these are used to evaluate a suite of image processing and analysis approaches, which are organized into a workflow. Our approach allows for us to identify key image processing and analysis steps that introduce the most error. Applicable dye configurations led to uncertainties of up to 41% depending on the selection of processing steps. Based on these findings, it was possible to delineate a flexible framework for image processing and analysis that has the potential for transfer and application in other tank experiment setups.

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“…ese barriers in pixel intensity can be solved by placing reference dots on both sides of the column to provide color information because the color of the reference dots does not change depending on lighting either from the light source or from the temporary shadows cast on the soil column. erefore, the pixel intensity of the reference dots can be used to correct changes in pixel intensity that result due to factors other than saturation [22,23,37].…”

Section: Basis Of Image Analysismentioning

confidence: 99%

“…eodoropoulou et al [19] proposed a high-resolution visualization method for the hydrodynamic diffusion of contaminants in transparent glass-etched pore networks. Other researchers have used laser scanning [20,21] or multiple cameras [22] to reconstruct the three-dimensional behavior of seepage. ese studies were implemented using PIV technology by adding fluorescent reflective particles to the fluid to produce patterns of image subset correlation.…”

Section: Introductionmentioning

confidence: 99%

An Improved Method for Quantifying Liquid Saturation Using Transparent Soil

Wang

Liu

Chen

et al. 2019

Advances in Civil Engineering

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Transparent porous media combined with digital image processing technology can be used to quantify the saturation of local fluids. In this regard, the calibration relationship between the pixel intensity of the image and the saturation of the wetting liquid is the crucial premise for whether this technique can be promoted and applied, and it is also a bottleneck that limits whether this technique can be rapidly and extensively developed. However, owing to gravity-driven effects, wetting liquid in a residual state usually exhibits an irregular boundary caused by the phenomenon of saturation overshoot, which makes it very difficult to use the previous overflow method to obtain the data pair of saturation-pixel intensity accurately. To this end, we have made some improvements to the specific testing method for wetting liquid saturation in the residual state and proposed a local centrifugal sampling method, which considerably improved the accuracy of this method. The results show that the relationship between the pixel intensity and saturation of the transparent soil obtained through this method is generally consistent with the regularity of the previous calibration method but shows better correlation. The results of this study will drive further potential application of transparent soil in the flow of partially saturated porous media.

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Methodology for Optical Imaging of NAPL 3D Distribution in Transparent Porous Media

Cited by 17 publications

References 54 publications

Quantification of Fluid Saturations in Transparent Porous Media

Quantification of Fluid Saturations in Transparent Porous Media

Quantification of Uncertainties from Image Processing and Analysis in Laboratory-Scale DNAPL Release Studies Evaluated by Reflective Optical Imaging

An Improved Method for Quantifying Liquid Saturation Using Transparent Soil

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