Transfert d'eau dans un milieu poreux non isotherme
(2000) Revue des Sciences de l’Eau — Vol. 13, n° 1, p. 75-84 (2000)
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- In most studies of liquid water flow, isothermal conditions are assumed. Since the beginning of the last century, several models and studies concerning mass and heat transfer hâve been conducted, but results didn't agrée on the effect of température and hydraulic gradients on water movement. Also, the relative importance of thèse différent gradients is not well known. Models used to quantify the simultaneous transfer of water due to température and water content gradients require a predetermination of thermal and iso-thermal coefficients of water diffusivity. Moreover soil characteristics must be known, mainly the relationships between hydraulic conductivity (K), pressure head (h), and water content (thêta). Measurements of water content, pressure head and température were done in a loamy sandy clay soil within a weighable lysimeter. The relationships between hydraulic conductivity, pressure head and water content were obtained from field and laboratory data. The water content gradient is generally less than those of température. Even with the maximum température gradient, the flux due to the water content gradient is more important than those due to the température gradient; the différence can reach 200%. Various field data (température, pressure head and water content) for différent field conditions concerning the mass transfer in both liquid and vapor phases resulting from hydraulic and température gradients were analyzed. Results show that when soil moisture is between the wilting point and field capacity, mass transfer occurs mostly in the liquid phase. This resuit confirms the validity of Darcy-Richards (DARCY, 1856; RICHARDS, 1931) équation where the effect of température is neglected. Also, the isothermal diffusivity of liquid water is very important when compared to ail other diffusivities.
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Daghari, H., & De Backer, L. (2000). Transfert d’eau dans un milieu poreux non isotherme. Revue des Sciences de l’Eau, 13(1), 75-84. https://doi.org/10.7202/705382ar (Original work published 2000)