摘要
弥散参数是计算地下水中溶质运移和污染预测时的重要参数。本文提出用Hermitian插值的特征有限元法计算含水层的弥散度和阻滞系数。砂槽试验表明,数值计算的结果和实际观测值以及解析解相当一致,有高的精确度。用本文提出的数值计算方法,可消除大部分的数值弥散和数值振荡,可实际应用于由于抽水或注水造成的辐射流的弥散试验中的求弥散参数问题。也可推广应用于其他的溶质运移问题的数值计算中。
Dispersivity and retardation factor are the important parameters for the computation of solute transport and prediction of ground water pollution. Usually they are determined by dispersion test. An artificial radiused flow field will be [formed by pumping or injecting during the testing period. In this paper it is proposed to estimate dispersion parameters by improved characteristic finite element method.The advective-dispersive equation can be expressed by the form of hydrodynamic derivative and the advective contribution can be estimated by the characteristic line method. The position of moving particles on the last time-step may be obtained by single-step reverse tracking. We computed the concentration of moving particles by Hermitian interpolation in the vicinity of steep front and by linear interpolation away from such front. The concentration of the moving particle is the advective contribution. The dispersive contribution can be estimated by the finite element approach. The method proposed in this paper can eliminate most of numerical dispersion and oscillation. The accuracy of the method is higher than the one with linear interpolation. The parameters can be estimated by the method above combined with optimization. The objective function is the sum of the square of the differences between computed concentrations and observed ones. Minimized the objective function, the parameters could be determined.In order to check the method proposed in this paper, we performed an injecting test in a sand box model. The results show that the concentration curves computed by the method above was in agreement with observed curves. The values of dispersivity and retardation factor estimated by our method coincided with analytical solutions. It means that the method proposed in this paper can put into practical use.
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
1992年第2期206-211,共6页
Chinese Journal of Hydrodynamics
基金
国家自然科学基金
关键词
抽水试验
特征有限元法
弥散参数
solute transport, advective-dispersive equation, pumping test, charac-teristic finite element method.
