Determining concentration fields of tracer plumes for layered porous media in flow-tank experiments |
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Authors: | Zhongbo Yu Franklin W Schwartz |
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Institution: | (1) The Earth System Science Center, The Pennsylvanian State University, 248 Deike Building, University Park, PA 16802, USA Fax: +1-814-865-3191, e-mail: yu@essc.psu.edu, US;(2) Department of Geological Sciences, The Ohio State University, Columbus, Ohio 43210, USA, US |
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Abstract: | In the laboratory, computer-assisted image analysis provides an accurate and efficient way to monitor tracer experiments.
This paper describes the determination of detailed temporal concentration distributions of tracers in a flow-tank experiment
by analyzing photographs of plumes of Rhodamine dye through the glass wall of the tank. The methodology developed for this
purpose consists of four steps: (1) digitally scanning black and white negatives obtained from photographs of the flow–tank
experiment; (2) calibrating and normalizing each digitized image to a standard optical-density scale by determining the relation
between the optical density and pixel value for each image; (3) constructing standard curves relating the concentration in
an optical density from five experimental runs with predetermined concentrations (2–97 mg/L); and (4) converting the optical
density to concentration. The spatial distribution of concentration for two photographs was determined by applying these calibration
and conversion procedures to all pixels of the digitized images. This approach provides an efficient way to study patterns
of plume evolution and transport mechanisms.
Received, March 1998 Revised, September 1998 Accepted, October 1998 |
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Keywords: | laboratory experiments tracer tests hydrochemistry variable-density flow image processing |
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