DOI: 10.5061/dryad.c4m181p
title: Data from: Unstable infiltration experiments in dry porous media

description: 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
 macroscopically 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.
description: Two-dimensional images
 of unstable infiltration in initially dry heterogeneous porous media in
 laboratory experimentsWe provide a data set of
 unstable infiltration into initially dry homogeneous and heterogeneous
 porous media. The data set contains small 2D experiments (Exp. 3-11 in
 Table 12 of the associated manuscript) as well as selected experiments
 conducted in large tanks. For small 2D experiments, radiographic images
 are provided, while large 2D experiments are documented via RGB images.
 Datasets contain a reference image "0.*" before the onset of
 finger formation, where the porous media in the domain, except for the
 upper fine layer, is completely dry. For the radiography dataset, the
 measured neutron intensity corresponds to I in Eq. [1-2] and the reference
 image “0.fits” corresponds to Idry in Eq. [2] of the manuscript. Datasets
 for radiography (Exp. 3-11) contain an additional empty
 "empty.fits" image where the flow cell is absent. Other
 filenames relate to time in seconds after onset of finger formation The
 radiography dataset (Exp. 3-11) is saved in the Flexible Image Transport
 System (FITS) format, which can be opened with common image processing
 tools such as ImageJ or computing environments such as Matlab. More
 information regarding the file format can be found at
 https://fits.gsfc.nasa.gov/fits_home.html. Each FITS file contains a 512
 by 512 matrix of pixelwise measured neutron intensities [neutrons/(px*s)].
 The dimensions of the pixels can be found in the table below. Fits files
 furthermore contain supporting information that has not been utilized in
 the manuscript but might prove useful, such as number of bits per data
 pixel and exposure time. For evaluation as conducted in the manuscript,
 the radiography raw data given in this dataset has been processed to
 eliminate the background noise with a wiener noise-removal filter. More
 Information on the radiography facility can be found at
 https://www.psi.ch/sinq/PublicationPolicyEN/NEUTRA.pdf.C3.vzj2016.10.0092.ds.zip