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Redistribution with air diffusion
Author(s) -
Philip J. R.,
Duijn C. J.
Publication year - 1999
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 - 10.1029/1999wr900115
Subject(s) - redistribution (election) , capillary pressure , hydraulics , mechanics , saturation (graph theory) , wetting , geotechnical engineering , environmental science , petroleum engineering , geology , thermodynamics , mathematics , porous medium , physics , porosity , politics , political science , law , combinatorics
Later work has revealed wider implications and applications of the similarity solution for redistribution of soil water with capillary hysteresis [ Philip , 1991]. The analysis involves continuity of both water potential and flow velocity across the interface between the draining and wetting regions. Two recent papers, however, claimed that in special circumstances, water potential is discontinuous across the interface and an “extended pressure condition” is needed. The apparent difficulty may be removed by recognizing that in the special case, hydraulics is not enough: volume conservation is maintained by diffusion of dissolved air. The extended pressure condition gives a useful approximation to the distribution of saturation but gets the potential distribution wrong and fails to recognize the air pressure differential between the two regions. Analogous conclusions apply to more general systems such as water/oil.