Van Genuchten model

The van Genuchten model (1980)¹ is a widely-used mathematical model for the Soil-Water Retention Curve (SWRC). It describes the relationship between the degree of saturation \(S^w\) and capillary pressure \(p^c\) in a porous medium. The numgeo keyword reads:

*Hydraulic = van Genuchten [, Swr = ]
alpha, n

The material parameters of the van Genuchten model are given in the following.

• \(\alpha\) is an empirical parameter with units of inverse pressure (e.g., kPa\(^{-1}\)).
• \(n > 1\) is an empirical parameter related to the pore-size distribution (dimensionless).
• \(S^{wr}\) (optional) is the residual degree of saturation (-).

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• Theory manual

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  The theory behind the implementation

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1. M. Th. van Genuchten. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44(5):892–898, 1980. URL: http://doi.wiley.com/10.2136/sssaj1980.03615995004400050002x (visited on 2022-04-07), doi:10.2136/sssaj1980.03615995004400050002x. ↩