Browsing by Author "Pollacco, Joseph"

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    Mixed formulation for an easy and robust numerical computation of sorptivity
    Lassabatere, Laurent; Peyneau, Pierre-Emmanuel; Yilmaz, Deniz; Pollacco, Joseph; Fernandez-Galvez, Jesus; Latorre, Borja; Moret-Fernandez, David; Di Prima, Simone; Rahmati, Mehdi; Stewart, Ryan D.; Abou Najm, Majdi; Hammecker, Claude; Angulo-Jaramillo, Rafael (Copernicus, 2023-02-24)
    Sorptivity is one of the most important parameters for the quantification of water infiltration into soils. proposed a specific formulation to derive sorptivity as a function of the soil water retention and hydraulic conductivity functions, as well as initial and final soil water contents. However, this formulation requires the integration of a function involving hydraulic diffusivity, which may be undefined or present numerical difficulties that cause numerical misestimations. In this study, we propose a mixed formulation that scales sorptivity and splits the integrals into two parts: the first term involves the scaled degree of saturation, while the second involves the scaled water pressure head. The new mixed formulation is shown to be robust and well-suited to any type of hydraulic function - even with infinite hydraulic diffusivity or positive air-entry water pressure heads - and any boundary condition, including infinite initial water pressure head, h -> -infinity. Lastly, we show the benefits of using the proposed formulation for modeling water into soil with analytical models that use sorptivity.
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    A scaling procedure for straightforward computation of sorptivity
    Lassabatere, Laurent; Peyneau, Pierre-Emmanuel; Yilmaz, Deniz; Pollacco, Joseph; Fernández-Gálvez, Jesús; Latorre, Borja; Moret-Fernández, David; Di Prima, Simone; Rahmati, Mehdi; Stewart, Ryan D.; Abou Najm, Majdi R.; Hammecker, Claude; Angulo-Jaramillo, Rafael (Copernicus, 2021-09-22)
    Sorptivity is a parameter of primary importance in the study of unsaturated flow in soils. This hydraulic parameter is required to model water infiltration into vertical soil profiles. Sorptivity can be directly estimated from the soil hydraulic functions (water retention and hydraulic conductivity curves), using the integral formulation of . However, calculating sorptivity in this manner requires the prior determination of the soil hydraulic diffusivity and its numerical integration between initial and final saturation degrees, which may be difficult in some situations (e.g., coarse soil with diffusivity functions that are quasi-infinite close to saturation). In this paper, we present a procedure to compute sorptivity using a scaling parameter, cp, that corresponds to the sorptivity of a unit soil (i.e., unit values for all parameters and zero residual water content) that is utterly dry at the initial state and saturated at the final state. The cp parameter was computed numerically and analytically for five hydraulic models: Delta (i.e., Green and Ampt), Brooks and Corey, van Genuchten-Mualem, van Genuchten-Burdine, and Kosugi. Based on the results, we proposed brand new analytical expressions for some of the models and validated previous formulations for the other models. We also tabulated the output values so that they can easily be used to determine the actual sorptivity value for any case. At the same time, our numerical results showed that the relation between cp and the hydraulic shape parameters strongly depends on the chosen model. These results highlight the need for careful selection of the proper model for the description of the water retention and hydraulic conductivity functions when estimating sorptivity.