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Unsaturated Flow Theory Including Interfacial Phenomena
Author(s) -
Gray William G.,
Hassanizadeh S. Majid
Publication year - 1991
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 - 10.1029/91wr01260
Subject(s) - wetting , momentum (technical analysis) , thermodynamics , porous medium , capillary action , mechanics , saturation (graph theory) , capillary pressure , energy–momentum relation , flow (mathematics) , energy balance , materials science , porosity , physics , mathematics , finance , combinatorics , economics , composite material
The macroscopic porous medium equations for mass, momentum, and energy transport for air, water, and solid phases and the interfaces between these phases are examined in light of the second law of thermodynamics. Attention is focused on the momentum balance for the water phase. Appropriate forms of the momentum balance are obtained, in general, for the slow flow situation and for the case when the water phase completely wets the solid. This last case suggests that the relative wettability of the water and air phases is an important dependent thermodynamic variable which contributes to the hysteretic nature of the capillary pressure versus saturation curve.