Analysis of water and heat flow in unsaturated‐saturated porous media

Abstract

This work investigates the theoretical and practical aspects of modeling water and heat flow in an unsaturated‐saturated flow domain. Field experiments were designed and complementary laboratory analyses were employed to measure the relevant physical quantities that would enable the significance of non‐isothermal effects to be determined. The Philip and de Vries non‐isothermal flow model was adapted to the more general pressure (or matric) head‐based approach and a new expression for the thermal liquid water diffusivity DTl is proposed. A general and versatile computer simulation program for modeling coupled non‐isothermal transport is developed. The influence of coupling on diurnal subsurface moisture and heat transfer is evaluated by comparing the isothermal and non‐isothermal transient numerical solutions to the heat and water transport problem. The results confirmed that coupling does not noticeably influence the temperature field, but does affect the evaporation and subsurface moisture fluxes. The non‐isothermal theory is applied to calculate evaporation from dry land surfaces.