非达西裂隙流对渗透性基岩中流场及溶质羽的影响

以基岩渗流方向与裂隙轴向呈45度角为例，探讨了当裂隙轴向与基岩水流斜交时，裂隙流的非达西程度对流场及溶质运移的影响.使用Comsol Multiphysics多物理场仿真软件构建了一个在中部包含水平单裂隙的正方形多孔介质模型，裂隙中的非达西流用Izbash方程去刻画，裂隙的上游基岩中存在持续的溶质源.随着裂隙水流的非达西程度逐渐增强，流场及污染物分布表现出如下特征:（1）裂隙中水流流速逐渐增大；流线在裂隙与基岩界面处的折射逐渐偏离折射定律；（2）裂隙水流的流向逐渐偏向基岩水流的渗流方向；（3）溶质羽宽度变宽但对称性逐渐降低；（4）溶质在水平方向上的浓度峰值逐渐降低，右侧浓度逐渐升高；（5）裂隙产生的回弥散对溶质运移作用逐渐增强，使裂隙中更多的溶质运移到了上层基岩中.总体而言，裂隙流的非达西程度对流场及污染物分布有着显著的影响. 

Impacts of Non-Darcian Flow in the Fracture on Flow Field and Solute Plumes in a Fracture-Aquifer System

In this study, a mathematical model with the intersection angle between the flow direction and the x axial direction of 45degree was developed to investigate the effect of non-Darcy parameter n on flow field and solute migration when flow is oblique crossing the fracture. The Comsol Multiphysics software was used to do such numerical simulation. The simulation area was assumed to be square with a horizontal fracture embedded in the middle.The flow in the fracture was assumed to be non-Darcian and can be described by the Izbash equation. A constant solute source has been assigned in the upper matrix. The results indicate the following phenomena as the power index in the Izbash equation(n) increases:(1) the fracture flow velocity increases, and the flow line at the matrix-fracture interfaces gradually deviates from the classical fraction law; (2) the flow direction in fracture gradually turns to the direction in the matrix; (3) the width of solute plume increases, while the symmetry of solute plume reduces; (4) the peak solute concentration in the horizontal section diminishes, and the solute concentration on the right sight of the model increases; (5) the effect of back dispersion caused by fracture on solute plume becomes stronger, which results in more solutes in the fracture migrated to the upper matrix. Overall, the non-Darcy flow fracture has a significant impact on the flow field and solute distribution.