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Properties of the Sorptivity for Exponential Diffusivity and Application to the Measurement of the Soil Water Diffusivity
Author(s) -
Braddock R. D.,
Parlange J. Y.,
Lisle I. G.
Publication year - 1981
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1981.03615995004500040006x
Subject(s) - sorptivity , thermal diffusivity , exponential function , power function , decoupling (probability) , power law , function (biology) , soil water , mathematics , water content , exponential decay , soil science , thermodynamics , mathematical analysis , environmental science , physics , statistics , geotechnical engineering , geology , compressive strength , control engineering , evolutionary biology , biology , nuclear physics , engineering
For certain diffusivities, first integral techniques can be used to decouple the soil‐water diffusion equation, in similarity form, into a set of first‐order equations. Such a decoupling is possible where the diffusivity depends on the water concentration, as either a power law or as an exponential function. Here we show that the exponential case is related to the power law case, but with some resulting complications. For this class of diffusivities, the solutions form a special class, and we generate some of their properties. In particular, the sorptivity can be represented by a simple relation to a universal function of the water content. This function is tabulated and compared with results obtained by another method, i.e., optimization. The results are applied to the measurement of soil‐water diffusivity.