Numerical modelling of transient contaminant migration problems in infinite porous fractured media using finite/infinite element technique. Part II: Parametric study
Numerical modelling of transient contaminant migration problems in infinite porous fractured media using finite/infinite element technique. Part II: Parametric study
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DOI：
10.1002/nag.1610180803
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发表时间：
1994-08
影响因子：
4
通讯作者：
Chong-bin Zhao;S. Valliappan
中科院分区：
文献类型：
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作者：
Chong-bin Zhao;S. Valliappan
本文通过引入一种新的渗流项表达式，从一般意义上考虑了多孔裂隙介质中的渗流效应。采用双孔隙度的概念，并采用迎风有限元方法制定了相关的表达式。考虑到问题域的无限扩展，提出了一种映射的瞬态无限元来模拟无限介质的远场。由于本映射瞬态无限元的质量传递函数是依赖于空间和时间变量，在无限多孔裂隙介质中的瞬态污染物迁移问题的机制，可以严格模拟，因为在任何感兴趣的时间的元素的属性矩阵进行评估。通过与解析解的比较，验证了本文方法的准确性、正确性和有效性。三种不同的时间离散方案进行了检查，发现无论是中心差分或向后差分近似是适合的迎风有限元模拟的瞬态污染物迁移问题。
The leakage effect in porous fissured media has been considered in a general sense by introducing a new expression of the leakage term in this paper. The double porosity concept is employed and the related expressions are formulated using the upwind finite element approach. Considering the infinite extension of the problem domain, a mapped transient infinite element has been presented to simulate the far field of the infinite medium. Since the mass transfer function of the present mapped transient infinite element is dependent on both space and time variables, the mechanism of transient contaminant migration problems in infinite porous fractured media can be rigorously simulated because the property matrices of the element are evaluated at any time of interest. By comparing the current numerical results with the analytical ones, the accuracy, correctness and effectiveness of the present method have been established. Three different time discretization schemes were examined and it was found that either the central difference or the backward difference approximation is suitable for the upwind finite element simulation of transient contaminant migration problems.