中文摘要：

天然地表水边界复杂，且处于不断的冲淤变化中。数值切割单元法可任意追踪拟合复杂动边界，且网格生成简单，在计算流体中具有重要的研究和应用价值。本文对数值切割单元法常用的直接插值法、虚源反射法和直接源项法的基本原理、适用条件及关键难点解决方面等进行了系统总结。结合地表水流的动力特性，给出数值切割法在复杂边界地表水模拟中的具体应用方法，提出在二维模拟中，可直接采用基于有限体积法的直接插值法进行数值切割，而在三维模拟中，联合采用sigma一网格及直接源项法可同时实现模型的准确性及高效性。最后，通过对比目前数值切割法在其它领域典型算例，提出数值切割单元法在崩岸、河工建筑和植物绕流模拟、高精度紊流模拟等地表水模型难题方面的应用前景。

英文摘要：

Most of the rivers and estuaries are characterized with complex boundary and fluvial processes. Sharpen immersed boundary method attracting increasing interest due to its flexibility in fitting the complex moving boundary and its simplicity in mesh-generation. After the symmetrical analysis of basic principle of its main methods （namely the cut-cell method, ghost-cell method and direct-forcing method）, this paper proposes specific method used in the free water with complex fluvial banks. The cut-cell method can be di- rectly used in the 2D model from its conservation property, while in 3D flow models, it seems that only di- rect-forcing models can be used from the perspective of the feasibility, and the combination of or-coordi- nate and sharpen-IBM can be used from the prospect the accuracy and the efficiency. By the comparative analysis of the cases in other field, also showed is the feasibility and prospects of the sharpen-IBM in the modeling of river bank collapse, man-made construction, flows around vegetable, and the turbulences with high precision.