网格单元法矢方向一致处理方法

Ensuring Normal Orientation Consistency by Numbering System of Mesh Edge

工程计算要求网格单元的法矢方向正确,即外形外表面的法矢向外,外形内表面的法矢向内。常用的处理方法是人工检查,但当曲面复杂,由很多小曲面片构成时,人工判断工作量大、时间长,为此提出了网格单元法矢方向一致处理方法。首先建立网格单元拓扑信息,再根据拓扑信息和两个网格单元在公共边上的首末顶点编号相反的原则对网格单元顶点在单元中重新编号,然后由网格顶点编号定义出网格单元一致的法矢方向。

The normal orientation of mesh elements is required to be correct in many engineering calculation areas, that is： the normal orientation of mesh elements of outer surfaces should be toward out and the normal orientation of inside surface should be toward inside. The general method for checking normal orientation is by manual work, but it is much burdensome and time consumed when model is complex with too many little surfaces, so an algorithm of checking normal orientation consistency is put forward. Firstly topological connection information of mesh elements is constructed. Then the beginning and ending vertex number of a shared edge by two adjacent mesh elements are renumbered to be mutually reversed. Finally the normal of mesh elements are changed to be consistent accordingly.