地下水溶质运移数值模拟中减少误差的新方法

地下水中污染物运移的数值模拟方法一直是学界的研究热点问题.而如何减少与消除对流-弥散方程数值解中浓度陡锋面附近的数值振荡与数值弥散,更是研究的前沿与难点.提出了一种地下水溶质运移数值模拟中减少数值弥散的新方法.该方法的核心思想是在水动力弥散系数上加上一个数值弥散估算值,得到一个修正弥散系数,用其替代方程中有明确物理意义的水动力弥散系数进行计算.并提出了一个参数——数值弥散因子(μ_NDF),可以根据研究需要进行参数分区并适当调节该因子的大小,从而达到控制数值振荡,减小数值弥散的目的.从一维到二维的多个数值算例的模拟计算结果表明,该方法能在消除数值振荡的基础上,较好地减少数值弥散,达到满意的精度.

New method for reducing the numerical error in solving the problem of contaminant transport in groundwater

The numerical simulation of the contaminant transport in subsurface porous media have been a hotspot for years.It is always considered to be tough to deal with the problems regarding the numerical dispersion and the oscillation around sharp front area of contaminants.This paper presents a new method which can reduce the numerical dispersion in the numerical modeling of the contaminant transport in groundwater.The core of the new method is adding a new numerical dispersion estimation term to the hydrodynamic dispersion coefficient and obtaining a modified hydrodynamic dispersion coefficient(MHDC).We use MHDC instead of the traditional hydrodynamic dispersion coefficient and put forward a new parameter of numerical dispersion factor(μ_NDF).The research area can be divided into different μ_NDF areas,and their values can be adjusted according to our needs.In this way,we can control the numerical oscillation and diminishing the numerical dispersion.The Simulated results of several examples from one-dimension problems to two-dimension problem indicate that the new method can considerably reduce the numerical dispersion on the basis of diminishing the numerical oscillation and obtain more precise simulation results.Hence,the new method is simple in theory,convenient in application and worth popularizing.