【摘要】 【目的】了解吸附性溶质在土壤中的运移规律,为土壤溶质运移机理研究和应用提供理论支持。【方法】利用溶质运移的对流-弥散理论、Laplace变换、超几何方程和特征有限元法,对溶质在土壤中的运移规律进行理论研究和数值模拟。【结果】给出了稳定流条件下,考虑随深度变化的一阶降解和随深度变化的线性平衡吸附时,一维溶质运移的对流-弥散方程;在初始浓度为0,半无限一维空间内第一类边界条件下,推导出了溶质相对浓度的准解析表达式;用特征有限元法建立了相应的数值模型。【结论】对比数值解和准解析解的计算数据可以看出,本研究所得准解析解是正确的;同时,数值计算所产生的误差很小,所得数值模型能满足实际工作对计算精度的要求,可用于实际工作。更多还原

【Abstract】 【Objective】 The study was to find the transport law of adsorbed solute in soils and to provide theoretical basis for mechanism research and applications of solute transport through soils.【Method】 The advection-dispersion theory,Laplace transform,hypergeometric equation and the characteristic finite element method were used for theory research and numerical simulation.【Result】 The advection-dispersion model of 1-D solute transport through soils with depth-dependent first-order degradation and depth-dependent linear equilibrium Absorption under steady state flow was studied,and a quasi-analytical solution describing the concentration distribution was deduced under the initial concentration zero and the first boundary condition of a semi-infinite 1-D space.The numerical model of the advection-dispersion model was constructed by the characteristic finite element method.【Conclusion】 It can be seen from comparing the numerical solutions to the quasi-analytical solutions that the quasi-analytical solution is right and errors caused by the numerical computation are so small that the numerical model perfectly meets the demand of calculating precision in practical work.更多还原