Fig. 5. Comparisons between model predictions and measured data of the relationship between volumetric water content and d/d for wet-aggregate soil, which aggregate size is 1.0 to 2.0 mm in diameter. Four model predictions are shown: four-layer model with sigmoidal weight functions, Eq. [10] (solid line), four-layer model with sigmoidal weight functions, Eq. [11] (dash dot line), four-layer model with linear weight functions (dash line), Friedman's model (dot line).