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

虽然描述土壤水分在温度梯度作用下运动的物理控制方程已经建立，但由于难以得到方程中所包含的土壤物理性质，因此很难对土壤水分运动进行模拟。大多数的属性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。对沙丘砂的水力特性进行了试验研究。本研究主要是对具有温度梯度的封闭土柱中水分运动进行试验研究。测定了土柱中含水量剖面、NaCl浓度剖面的变化。对实验数据的分析给出了由于温度梯度引起的水蒸气运动系数作为含水量的函数。在低含水量时，空气和土壤中的水汽扩散比β系数较小，但当体积含水量大于0.04时，β系数可达1.5。将物理输运特性表示为含水量和温度的函数，得到了控制输运现象的偏微分方程的数值解。计算的含水量曲线与观察到的相似。

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.