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为研究非饱和土壤水分运动方程中参数的平均方式对层状土水分运动数值模拟的影响,采用有限差分方法对Richards方程进行离散,并用MATLAB软件编程模拟层状夹砂土柱的薄层积水入渗过程。对差分网格中半节点参数的8种不同平均方式进行了数值模拟稳定性和精度的比较。结果表明:不同平均方式下湿润峰到达某一深度的时间与该处的土壤含水量增速呈负相关关系;间接算术平均和调和平均下的土壤含水率数值振荡较大;几何平均和三点平均2种方式下入渗率、累积入渗量和湿润锋误差相对较小。综合分析,几何平均和三点平均更适合层状夹砂土情况下薄层积水入渗过程的数值模拟。
In order to study the influence of the average parameter of unsaturated soil moisture equation on the numerical simulation of water movement in layered soil, the Richards equation is discretized by finite difference method. The thin-layer water of layered sand-soil column is simulated by MATLAB software Infiltration process. The stability and accuracy of numerical simulations were compared for eight different averaging methods of half-node parameters in differential grid. The results show that the time when the wetting peak reaches a certain depth is negatively correlated with the growth rate of soil water content under the different average methods. The values of soil moisture content under indirect arithmetic mean and harmonic mean oscillation are large. The geometric mean and three-point The average infiltration rate, cumulative infiltration rate and wetting front error are relatively small in the average of 2 ways. Comprehensive analysis, geometric average and three-point average are more suitable for the numerical simulation of thin-layer infiltration process under the condition of layered sand.