Details
| Original language | English |
|---|---|
| Number of pages | 13 |
| Journal | Vadose zone journal |
| Volume | 16 |
| Issue number | 7 |
| Publication status | Published - 6 Jul 2017 |
Abstract
Prediction of infiltration in porous media is challenged by finger formation and unstable displacement of the wetting front. We present a systematic experimental study on the effect of packings and infiltration rates on unstable flow into initially dry porous media. We conducted small two- and three-dimensional experiments where water contents were measured with neutron radiography and larger two-dimensional experiments, which we evaluated by obtaining commonly used finger properties such as width and velocity from image analysis. Our results from experiments in mac-roscopically homogeneous packings were tested for correspondence with theoretical finger property predictions and are in good agreement. For the smaller experiments, water content profiles including “overshoots” at the finger tips as well as finger properties depending on the packing matched well results reported in the literature. For all homogeneous experiments, we found a strong dependence of finger properties on porosity. Homogeneous experiments served as reference cases for comparison with larger two-dimensional experiments where heterogeneity was induced by block-shaped inclusions. Unstable flow propagation in heterogeneous experiments was documented by inclusion fill rates in addition to finger properties. We found a multifaceted finger propagation behavior that depends on the impingement position of instabilities on an inclusion. Thereby, we are able to show that the location of the impingement on an inclusion is crucial to the filling rate of the inclusion and the propagation velocity of the finger. Results from the conducted experiments present a data set for testing of extended Richards’ models.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Soil Science
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In: Vadose zone journal, Vol. 16, No. 7, 06.07.2017.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Unstable infiltration experiments in dry porous media
AU - Cremer, C. J.M.
AU - Schuetz, C.
AU - Neuweiler, I.
AU - Lehmann, P.
AU - Lehmann, E. H.
N1 - Funding information: We would like to thank the Deutsche Forschungsgemeinschaft (DFG) for financial support within the scope of the MUSIS project (Grant no. NE 824/6-2). Furthermore, we thank Frank Spitzenberg for providing laboratory measurements of glass bead hydraulic conductivity from his Darcy experiments.
PY - 2017/7/6
Y1 - 2017/7/6
N2 - Prediction of infiltration in porous media is challenged by finger formation and unstable displacement of the wetting front. We present a systematic experimental study on the effect of packings and infiltration rates on unstable flow into initially dry porous media. We conducted small two- and three-dimensional experiments where water contents were measured with neutron radiography and larger two-dimensional experiments, which we evaluated by obtaining commonly used finger properties such as width and velocity from image analysis. Our results from experiments in mac-roscopically homogeneous packings were tested for correspondence with theoretical finger property predictions and are in good agreement. For the smaller experiments, water content profiles including “overshoots” at the finger tips as well as finger properties depending on the packing matched well results reported in the literature. For all homogeneous experiments, we found a strong dependence of finger properties on porosity. Homogeneous experiments served as reference cases for comparison with larger two-dimensional experiments where heterogeneity was induced by block-shaped inclusions. Unstable flow propagation in heterogeneous experiments was documented by inclusion fill rates in addition to finger properties. We found a multifaceted finger propagation behavior that depends on the impingement position of instabilities on an inclusion. Thereby, we are able to show that the location of the impingement on an inclusion is crucial to the filling rate of the inclusion and the propagation velocity of the finger. Results from the conducted experiments present a data set for testing of extended Richards’ models.
AB - Prediction of infiltration in porous media is challenged by finger formation and unstable displacement of the wetting front. We present a systematic experimental study on the effect of packings and infiltration rates on unstable flow into initially dry porous media. We conducted small two- and three-dimensional experiments where water contents were measured with neutron radiography and larger two-dimensional experiments, which we evaluated by obtaining commonly used finger properties such as width and velocity from image analysis. Our results from experiments in mac-roscopically homogeneous packings were tested for correspondence with theoretical finger property predictions and are in good agreement. For the smaller experiments, water content profiles including “overshoots” at the finger tips as well as finger properties depending on the packing matched well results reported in the literature. For all homogeneous experiments, we found a strong dependence of finger properties on porosity. Homogeneous experiments served as reference cases for comparison with larger two-dimensional experiments where heterogeneity was induced by block-shaped inclusions. Unstable flow propagation in heterogeneous experiments was documented by inclusion fill rates in addition to finger properties. We found a multifaceted finger propagation behavior that depends on the impingement position of instabilities on an inclusion. Thereby, we are able to show that the location of the impingement on an inclusion is crucial to the filling rate of the inclusion and the propagation velocity of the finger. Results from the conducted experiments present a data set for testing of extended Richards’ models.
UR - http://www.scopus.com/inward/record.url?scp=85024112877&partnerID=8YFLogxK
U2 - 10.2136/vzj2016.10.0092
DO - 10.2136/vzj2016.10.0092
M3 - Article
AN - SCOPUS:85024112877
VL - 16
JO - Vadose zone journal
JF - Vadose zone journal
SN - 1539-1663
IS - 7
ER -