不同覆盖条件对土壤水热分布影响的计算机模拟Ⅱ——有限元分析及应用

在本研究的第一部分已建立了数学模型的基础上,本文进行了有限元分析。应用Galerkin法进行了空间域的离散,应用差分法及Douglas-Dapont预报校正法完成了时间域的离散及非线性处理。然后用Fortran-77编写了计算机程序,实现了不同覆盖层下非匀质土壤水热分布的定量分析,并进行了田间实验验证。计算与验证结果表明:塑膜膜侧种植校膜中心种植在地温稍高含水量稍低的情况下,可节约用膜7%;透水率很低的纸张在改进耐久性的基础上可能在一定条件下作为塑膜的代用品。

SIMULATION OF ULCH EFFECTS ON SOIL TEMPERATUREAND MOISTURE REGIMES PART II: FINITE ELEMENTANALYSIS AND APPLICATION

On the basis of the mathematical model was developed in part I, the governing equations were solved by the Galerkin-type finite element approach, together with the Douglas-Dapout Prediction-Correction method which have the advantage of less computer time than the itera-tive procedure for nonlinear problems. A simulation program for the influence of mulches on the seedbed moisture and heat behaviour was compiled and validated with the field experiment. Preliminary application of the program in analyzing the influence of the clear polyethylene film, oil paper and wheat straw on with different mulching technologies on seedbed moisture and temperature regimes put forth the following findings: (1) Transparent PE strip with planting alongside the edges of the film strip can save 7 percent of film material with slightly higher temperature and slightly lower soil moisture as compared to the prevailing common practice at the middle of the film strip. (2) Under certain condition, strengthened paper ma-terial properly treated with oil is a promising alternative to replace the polyethylene film.