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

虽然描述温度梯度下土壤水分运动的物理控制方程已知，但由于方程中包含的土壤物理性质难以获得，因此很难模拟土壤水分运移现象。大多数性能强烈地依赖于水分含量。本研究的目的是模拟温度梯度下的水分运动。通过多次试验，对沙丘沙地的水力特性进行了测试。本研究主要针对具有温度梯度的封闭土柱中的水分运动进行实验研究。测定了土柱含水率剖面、盐分浓度剖面的变化。通过对实验数据的分析，给出了温度梯度引起的水蒸气运动系数与含水率的函数关系。水分在空气和土壤中的扩散比β系数在低含水率时较小，但在体积含水率高于0.04时达到1.5。将物理输运性质表示为水分和温度的函数，得到了输运现象的偏微分方程组的数值解。计算得到的含水率剖面与观测到的相似。

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.