大区域含水层中局部复杂水流过程的多尺度模拟

发布时间：2018-10-08 13:26

【摘要】：精细刻画带有小尺度特征的局部复杂水流运动过程,是大区域地下水流运动数值模拟的重要议题。本文建立了一种能进行多时空尺度数值离散的三维地下水流运动耦合模型,用以获取全区域大尺度解及多子域小尺度高精度解。模型采用基于达西定律的三维水头插值算法,以实现多空间尺度模型耦合;同时,针对局部复杂水流条件,进行小尺度模型边界水头二阶时间曲线拟合及自适应时间步长插值,以实现多时间尺度模型耦合;此外,在局部问题的求解上支持任意边界形状及空间范围内的多个自由加密子网格离散,从而充分节省计算成本并保证计算精度。本文以通用地下水模型求解软件MODFLOW在高密度时空网格上的解作为参照解,对比分析了模型在多时空尺度、非匹配自由网格问题中的求解精度。相比传统局部加密或全局加密模型方法,本文模型能大幅度减小矩阵规模和求解工作量;相比传统局部加密多网格耦合模型,本文模型能更精确地刻画局部尺度的复杂水流运动过程。本文模型耦合方案可作为大区域含水层中精细刻画小尺度复杂水流过程的高效数值工具。
[Abstract]:It is an important issue in numerical simulation of large area groundwater flow to depict the local complex flow process with small scale characteristics. In this paper, a three-dimensional coupled model of groundwater flow is established, which can be discretized numerically in multiple time and space scales. The model is used to obtain the large scale solution in the whole region and the high accuracy solution in small scale in multiple subdomains. The model adopts the Darcy's law based 3D water head interpolation algorithm to realize the multi-scale model coupling, at the same time, according to the local complex flow condition, the second order time curve fitting and the adaptive time step interpolation of the small scale model boundary water head are carried out. In order to realize the multi-time scale model coupling, in addition, the local problem can be solved by discretization of several free encryption subgrids in arbitrary boundary shape and space range, thus fully saving computation cost and guaranteeing calculation accuracy. In this paper, the solution of the general groundwater model solution software MODFLOW on high density space-time grid is used as the reference solution, and the accuracy of the model in multi-space-time scale, non-matching free grid problem is compared and analyzed. Compared with the traditional local encryption or global encryption model, this model can greatly reduce the matrix size and solve the workload, compared with the traditional local encryption multi-grid coupling model, The model in this paper can more accurately describe the local scale of complex flow processes. The model coupling scheme in this paper can be used as an efficient numerical tool for the fine characterization of small-scale complex flow processes in large regional aquifers.
【作者单位】：武汉大学水资源与水电工程科学国家重点实验室;
【基金】：国家自然科学基金项目(51479143) 内蒙古自治区水利科技计划项目([2014]117-02)
【分类号】：P641

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