Investigation of dispersion in porous media using fiber-optic technology

Nielsen, J M; Pinder, George F.; Kulp, T J; Angel, S. M.

doi:10.2172/10191395

Cited by 4 publications

(4 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fiber optic spectroscopy has received considerable attention in subsurface hydrology [ Kulp et al , 1988; Nielsen et al , 1991; Barczewki and Marschall , 1992; Benischke and Leitner , 1992; Ghodrati , 1999]. Fiber optic sensors, in combination with fluorescence spectroscopy, offer the possibility of measuring tracer concentrations in situ.…”

Section: Analysis Of Dye Tracing Experimentsmentioning

confidence: 99%

Dyes as tracers for vadose zone hydrology

Flury

Wai

2003

Reviews of Geophysics

242

166

View full text Add to dashboard Cite

[1] Dyes are important tracers to investigate subsurface water movement. For more than a century, dye tracers have provided clues about the hydrological cycle as well as flow and transport processes in the subsurface. Groundwater contamination often originates in the vadose zone. Agrochemicals applied to the soil surface, toxic compounds accidentally spilled by human activities, and contaminants released from waste repositories leach through the vadose zone and can ultimately pollute groundwater resources. Dyes are an important tool to assess flow pathways of such contaminants. This review compiles information on dyes used as hydrological tracers, with particular emphasis on vadose zone hydrology. We summarize briefly different human-applied tracers, including nondye tracers. We then provide a historical sketch of the use of dyes as tracers and describe newer developments in visualization and quantification of tracer experiments. Relevant chemical properties of dyes used as tracers are discussed and illustrated with dye intermediates and selected dye tracers. The types of dyes used as tracers in subsurface hydrology are summarized, and recommendations are made regarding the use of dye tracers. The review concludes with a toxicological assessment of dyes used as hydrological tracers. Many different dyes have been proposed as tracers for water movement in the subsurface. All of these compounds, however, are to some degree retarded by the subsurface medium. Nevertheless, dyes are useful tracers to visualize flow pathways.

show abstract

Section: Analysis Of Dye Tracing Experimentsmentioning

confidence: 99%

Dyes as tracers for vadose zone hydrology

Flury

Wai

2003

Reviews of Geophysics

242

166

View full text Add to dashboard Cite

show abstract

“…The fluorescein concentration was detected by in situ fiber-optic fluorometry [Nielsen et al, 1991]. Fiberoptic probes were located in the inlet and the outlet of the helix and connected to a multichannel fluorometer, provided by Hermes Messtechnik, Stuttgart, Germany.…”

Section: Device and Proceduresmentioning

confidence: 99%

Experimental determination of transverse dispersivity in a helix and a cochlea

Benekos

Cirpka

Kitanidis

2006

Water Resources Research

View full text Add to dashboard Cite

[1] In porous media, transverse dispersion plays a decisive role in the dilution of conservative solutes, the decay of concentration fluctuations, and the mixing of reactive solutes. One possible approach for measuring the transverse dispersivity of homogeneous isotropic porous media is based on the principle of Taylor-Aris dispersion, where the longitudinal macrodispersion coefficient is inversely proportional to the pore-scale transverse dispersion coefficient. Taylor-Aris dispersion requires a shear flow situation. To achieve the latter in porous media, we use a helix, as previously proposed, and also a cochlea, which is spiral-shaped cavity resembling the interior a nautilus shell. We obtain experimental breakthrough curves from conservative tracer experiments and compare them to results of numerical simulation. By fitting the model we obtain the values of transverse dispersivity in various tracer tests. In our experiments we investigate porous media with relatively uniform particle distributions. Estimates of the transverse dispersivity are obtained for each experiment, and the relative advantages of each device are discussed. The two devices yield similar results. The estimated ratio of transverse dispersivity to longitudinal dispersivity agrees with the higher ratios reported in the literature.

show abstract

“…We measure the concentration of fluorescein by fiber‐optic fluorometry [ Nielsen et al , 1991; Ghodrati , 1999; Jose and Cirpka , 2004]. Two probes are installed in the inlet chambers, 19 probes in flow‐through cells between the outlet chambers and the hydraulic switchboard, and 126 measurement locations are provided within the filling of the sandbox.…”

Section: Methodsmentioning

confidence: 99%

Large‐scale sandbox experiment on longitudinal effective dispersion in heterogeneous porous media

Jose

Rahman

Cirpka

2004

Water Resources Research

View full text Add to dashboard Cite

[1] In heterogeneous media the breakthrough curves observed at single points may differ significantly from those integrated over a control plane. While standard macrodispersion describes the spread of concentration averaged over the entire cross section, effective dispersion quantifies the average spread in the locally observed breakthrough curves. We perform a conservative tracer test in a 14-m-long sandbox filled heterogeneously with four types of silica sand. The filling resembles natural heterogeneities including the distribution of facies and micro-structures within the various sand types. We use fluorescein as tracer, which we measure at 126 measurement points directly within the porous medium and at 19 levels in the outlet of the domain. We use fiber-optic probes with a point-like measurement tip for fluorescence intensity measurements. From the second central temporal moments of the locally obtained breakthrough curves we compute apparent effective dispersion coefficients, and from the average over all probes within a measurement plane we derive apparent macrodispersion coefficients. The effective dispersion coefficient is about two thirds of the macrodispersion coefficient. Considering the typical length scales of the heterogeneities, the experimental findings are qualitatively in agreement with linear stochastic theory.

show abstract

Investigation of dispersion in porous media using fiber-optic technology

Cited by 4 publications

References 7 publications

Dyes as tracers for vadose zone hydrology

Dyes as tracers for vadose zone hydrology

Experimental determination of transverse dispersivity in a helix and a cochlea

Large‐scale sandbox experiment on longitudinal effective dispersion in heterogeneous porous media

Contact Info

Product

Resources

About