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Titel |
On the measurement of solute concentrations in 2-D flow tank experiments |
VerfasserIn |
M. Konz, P. Ackerer, E. Meier, P. Huggenberger, E. Zechner, D. Gechter |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1027-5606
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Digitales Dokument |
URL |
Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 3 ; Nr. 12, no. 3 (2008-05-14), S.727-738 |
Datensatznummer |
250010654
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Publikation (Nr.) |
copernicus.org/hess-12-727-2008.pdf |
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Zusammenfassung |
In this study we describe and compare photometric and resistivity
measurement methodologies to determine solute concentrations in porous media
flow tank experiments. The first method is the photometric method, which
directly relates digitally measured intensities of a tracer dye to solute
concentrations, without first converting the intensities to optical
densities. This enables an effective processing of a large number of images
in order to compute concentration time series at various points of the flow
tank and concentration contour lines. This paper investigates perturbations
of the measurements; it was found both lens flare effects and image
resolution were a major source of error. Attaching a mask minimizes the lens
flare. The second method for in situ measurement of salt concentrations in
porous media experiments is the resistivity method. The resistivity
measurement system uses two different input voltages at gilded electrode
sticks to enable the measurement of salt concentrations from 0 to 300 g/l.
The method is highly precise and the major perturbations are caused by
temperature changes, which can be controlled in the laboratory. The two
measurement approaches are compared with regard to their usefulness in
providing data for benchmark experiments aimed at improving process
understanding and testing numerical codes. Due to the unknown measurement
volume of the electrodes, we consider the image analysis method more
appropriate for intermediate scale 2D laboratory benchmark experiments for
the purpose of evaluating numerical codes. |
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