Diffusivity and One-Dimensional Absorption Experiments
1983
Clothier, B. E. | Scotter, D. R. | Green, A. E.
Profiles of normalized volumetric soil water content, Θ, during one-dimensional absorption are often found to provide a unique profile in terms of the Boltzmann similarity variable, λ. Traditionally, λ(Θ) data have been used to obtain the diffusivity-water content function D(Θ) by the method of Bruce and Klute. This paper highlights the well-known inadequacy of this method, and outlines a procedure for deriving D(Θ) by the fitting of a mathematical function to the primary experimental data set, namely λ(Θ). An analytical expression for D(Θ) scaled by sorptivity is provided. A function of the form (1-Θ)ᵖ is shown to fit the λ(Θ) of a fine sand adequately and provide a D(Θ) function that accommodates the soil water diffusivity measured using other methods at near-saturation.
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