Heat Transport and Formation of Moisture, Temperature Environments in Soil.

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Although the physical governing equations that describe the soil water movement under temperature gradients have been known, it is hard to simulate the transport phenomena because of the difficulty of getting the soil physical properties included in the equations. Most of the properties depend strongly on moisture contents. The goal of this study to simulate the water movement under temperature gradients. The hydraulic properties of the Sand Dune Sand were measured conducting several experiments. The main experiments in this study is of the water movement in closed soil column with temperature gradients. The changes in water content profiles, NaCl concentration profiles in the soil columns were measured. The analysis of the experimental data gave the coefficient of water vapor movement due to temperature gradients as the function of water content. The coefficient of beta, the ratio of water vapor diffusion in air and in soil, is small at low water content, but is up to 1.5 at higher volumetric water content than 0.04. Expressing the physical transport properties as the functions of water content and temperature, the numerical solution to the partial differential equations governing the transport phenomena were obtained. The calculated water content profiles were similar to these observed.