土壤水分运移温度效应的数值研究

Numerical study of the temperature effect on the transportation of soil water

分析了土壤水分运移温度效应的机理,基于“表面张力-粘滞流理论”对“六场-相变-扩散模型”中的土水势、非饱和水力传导系数和水分扩散系数三个参数进行了改进,即考虑了它们的温度效应,继而通过对0.2 m×0.2 m的二维砂土剖面的热湿耦合运移进行了为期60 d的数值计算,通过比较原模型和改进模型的计算结果,考察了土壤水分运移温度效应的大小.计算结果表明:第10 d,20 d,30 d,40 d,50 d和60 d时,温度效应对土壤水分含量的相对影响分别为4.98%,5.57%,6.23%,6.96%,7.78%和8.7%.同时发现,土壤水分运移的温度效应在土壤表层表现得最为明显.

The mechanism of temperature effect on the transportation of soil water was analyzed. On the basis of the “Surface Tension-Viscous Flow” theory, some modifications were made to the soil water potential, non-saturation hydraulic conductivity and water diffusivity involved in the current “Six fields-Phase change-Diffusion” model, etc. In the modified model, the temperature effect was taken into consideration. The numerical simulations for 60 days were conducted on a two-dimension domain of 0.2 meter by 0.2 meter. The comparison between the calculation results of the original model with the calculation ones of the improved model was made and the temperature effect on the transportation of soil water studied. It was seen that the temperature effect on soil water content are 4.98 %,5.57 % ,6.23 % ,6.96 %, 7.78 % and 8.70 %, respectively when it is at the 10th day, 20th day, 30th day, 40th day, 50th day and 60th day. The temperature effect on soil water transportation could be the most distinctly observed in the upper layer of soil.