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Relating capillary pressure to interfacial areas
Author(s) -
PyrakNolte Laura J.,
Nolte David D.,
Chen Daiquan,
Giordano Nicholas J.
Publication year - 2008
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 - 10.1029/2007wr006434
Subject(s) - capillary pressure , capillary action , wetting , imbibition , curvature , capillary length , materials science , capillary number , saturation (graph theory) , mechanics , surface tension , volume (thermodynamics) , volume of fluid method , capillary surface , porous medium , composite material , porosity , thermodynamics , geometry , flow (mathematics) , mathematics , physics , germination , botany , combinatorics , biology
Experiments were performed on transparent two‐dimensional microfluidic porous systems to investigate the relationships among capillary pressure and the interfacial areas per volume between two fluid phases and one solid phase. Capillary pressures were calculated from the observed interfacial curvature of the wetting‐nonwetting interface, and these correlated closely to externally measured values of applied pressure. For each applied pressure, the system established mechanical equilibrium characterized by stationary interfaces, uniform curvatures across the model, and random surface normals. To study the relationships among capillary pressure and the interfacial areas, we compare the curvature‐based capillary pressure with the differential change in interfacial areas per volume as a function of wetting‐phase saturation. The differential pressure contributions calculated from the experimental measurements are found to be nearly independent of the measured capillary pressure. These results suggest that other contributions to the capillary pressure must be significant when imbibition and drainage processes result in saturation gradients.