Geophysical Research Letters

Morphology, propagation dynamics and scaling characteristics of drying fronts in porous media

Authors

  • N. Shokri,

    Corresponding author
    1. Department of Earth Sciences, Boston University, Boston, Massachusetts, USA
      Corresponding Author: N. Shokri, Department of Earth Sciences, Boston University, 675 Commonwealth Ave., Boston, MA 02215, USA. (nshokri@bu.edu)
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  • Muhammad Sahimi,

    1. Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California, USA
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  • D. Or

    1. Soil and Terrestrial Environmental Physics, Department of Environmental Sciences, ETH Zurich, Zurich, Switzerland
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Corresponding Author: N. Shokri, Department of Earth Sciences, Boston University, 675 Commonwealth Ave., Boston, MA 02215, USA. (nshokri@bu.edu)

Abstract

[1] Effects of surface wettability on the dynamics and morphology of evaporation-induced drying fronts (DF) receding into hydrophilic (HI) or hydrophobic (HO) sands were studied using highly-resolved neutron radiography. A more pronounced pinning-depinning motion (larger steps and longer waiting times) was observed for the DF in HI sand relative to HO, due to weaker capillary pinning forces in the latter. For length scalesl smaller than a correlation length ξ, quenched disorder dominates DF roughness expressed by a roughness exponent α = 0.77, whereas for l > ξ the fluctuations induced by the DF motion annealed the disorder and result in α= 0.44. Although wettability suppressed evaporation rates in HO relative to HI sand, differences in the evaporation dynamics and pinning behavior did not alter the DF morphology indicators-the fractal dimension and roughness exponent-which remained similar for the HI and HO sands.

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