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A Two‐Phase Numerical Model for Prediction of Infiltration: Applications to a Semi‐Infinite Soil Column
Author(s) -
MorelSeytoux Hubert J.,
Billica Judith A.
Publication year - 1985
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/wr021i004p00607
Subject(s) - infiltration (hvac) , phase (matter) , column (typography) , a priori and a posteriori , boundary value problem , richards equation , mathematics , flow (mathematics) , two phase flow , mechanics , mathematical optimization , soil water , soil science , mathematical analysis , environmental science , thermodynamics , geometry , physics , philosophy , connection (principal bundle) , epistemology , quantum mechanics
A numerical algorithm for prediction of infiltration and water content profiles evolution in a soil column is presented. The algorithm is derived from the two‐phase flow theory for water and air. However, the governing equations reduce to the usual one‐phase flow equations by setting a parameter to a zero value. The model can shift back and forth from the one‐phase to the two‐phase mode within the course of a simulation as demanded by the situation. The need for the two‐phase approach is demonstrated for a couple of illustrative situations both with a semi‐infinite lower boundary condition, that is, for a case when the two‐phase approach might appear a priori least needed. It is shown that it is indeed needed even for a semi‐infinite soil column when mobile air cannot be confined. Rather amazingly the two‐phase computer runs cost less than the corresponding one‐phase runs. It is shown that the two‐phase algorithm is naturally more stable than the one‐phase algorithm when the water contents are high in a portion of the column. Thus the two‐phase approach is not only more realistic, but it is even less expensive whenever it is needed.