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Gravity drainage analysis for scale heterogeneous porous materials under falling water table conditions
Author(s) -
Watson K. K.
Publication year - 1987
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/wr023i005p00818
Subject(s) - drainage , water table , pressure head , outflow , mechanics , porosity , geology , scale (ratio) , falling (accident) , flow (mathematics) , porous medium , geotechnical engineering , groundwater , physics , thermodynamics , medicine , ecology , oceanography , environmental health , quantum mechanics , biology
The gravity drainage of two profiles of porous material exhibiting scale heterogeneity in the vertical direction is studied for stationary and falling water table conditions using a computer‐based numerical analysis of the partial differential equation describing flow in unsaturated porous materials. Results presented in the form of pressure head profiles indicate the complex pressure head conditions that may arise with certain distributions of heterogeneity and certain rates of fall of the water table. Equations based on the Green and Ampt assumptions are also developed for the gravity drainage process in scale heterogeneous materials, and results using the sharp‐front model are compared with the numerically obtained results. The comparisons in terms of the relationship between cumulative drainage outflow and time showed satisfactory correspondence when the median grain size of the heterogeneous profile lay in the fine sand range. However, the correspondence was less satisfactory for a profile with a coarse sand median grain size.