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Analysis of a capillary hysteresis model based on a one‐variable distribution function
Author(s) -
Mualem Y.,
MorelSeytoux H. J.
Publication year - 1978
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/wr014i004p00605
Subject(s) - hysteresis , wetting , function (biology) , porous medium , mathematics , capillary action , radius , water content , mathematical analysis , mechanics , porosity , thermodynamics , geotechnical engineering , physics , geology , computer science , computer security , quantum mechanics , evolutionary biology , biology
Parlange's (1976) model corresponds to a special case of Mualem's similarity hypothesis ƒ(ψ w , ψ d ) = h (ψ w ) l (ψ d ) in which h (ψ) is set at unity for all ψ values. Interpreted in terms of the soil water domain theory this assumption implies that the relative pore volume of the domains is distributed uniformly in respect to the wetting radius (or to ψ w ). In this paper the proper mathematical equation is derived for calibrating the model from the experimental main drying curve. The applicability of Parlange's model for the soil water hysteresis is theoretically analyzed and extensively tested for different types of porous media. Theoretical hysteretic curves derived by direct implementation of Parlange's model are compared with experiments. These comparisons show that Parlange's model contradicts well‐known properties of the soil moisture characteristics. The good results reported by Parlange are not obtained when actual measured curves of the hysteresis loop are used. Whether the main branch of hysteresis for wetting or for drying is used in calibration, one obtains badly distorted shapes of hysteresis curves. Parlange's suggestion for calibrating the model on the basis of the main drying curve plus one additional point from the main wetting curve is considered too arbitrary to be reliable.