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Dynamic capillary pressure during water infiltration: Experiments and Green‐Ampt modeling
Author(s) -
Pellichero Emanuele,
Glantz Roland,
Burns Meghan,
Mallick Debjani,
Hsu ShaoYiu,
Hilpert Markus
Publication year - 2012
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2011wr011541
Subject(s) - infiltration (hvac) , ponding , capillary action , wetting , mechanics , capillary pressure , transient flow , geotechnical engineering , materials science , geology , porous medium , physics , composite material , meteorology , porosity , ecology , surge , drainage , biology
In a recent study by Hsu and Hilpert (2011), the Green‐Ampt (GA) model for water infiltration was modified to account for a dynamic capillary pressure that depends on the wetting front velocity. In that study, the only transient flow, to which the modified GA approach was compared, was capillary rise. In this paper, transient downward infiltration experiments were performed using three different ponding depths. We demonstrated that infiltration can be effectively modeled using the modified GA approach. The parameters of the dynamic capillary pressure relationship were fitted and independent of the ponding depth. Furthermore, the experimental data could not be described accurately at early times with the classical GA approach. This was particularly evident when plotting the product between the Darcy velocity and the wetting front position against the wetting front position. In these plots, the initial unphysical infinite rate of infiltration, that occurs in the classical GA model, appears to be a primary element of inaccuracy. It was furthermore verified that the limited ability of the classical GA approach to describe the experimental data is not related to inertial forces arising during the initial phase of infiltration.