重叠网格技术中割补法的研究与改进

针对计算流体力学中重叠网格生成困难的问题,分析了重叠网格自动生成技术中割补法的主要特点和基本流程,指出其在洞映射单元属性的判断方法和洞边界外推过程中出现的"孤点"现象等方面的问题,提出了合理的改进方案,并将改进后的方法应用到自适应嵌入网格和DRAGON网格的生成中,最后编制出通用程序并给出了三维算例.实际应用表明,改进后的方法具有更稳定、自动化程度更高、适用范围更广的特点.

Investigation and enhancement of cut-paste algorithm in overlapping grid

To solve the problem in generation of overlapping grids in CFD (co mputational fluid dynamics) automatically, the main characteristics and basic fl ow of the newly emerged cut-paste algorithm which generates overlapping grids b y cutting and pasting hole fronts were investigated. The promising advantages of t his algorithm were introduced, yet two main disadvantages were putted forth. In the conventional algorithm, one may gets failed in the judgement of attributes o f hole-mapping cells when walls are not closed totally. It is a big obstacle to implement of this algorithm in many applications. The undesired "orphan" cells may occur when hole boundaries expand out during the cut phase. Enhanceme nts were made on these aspects to improve this algorithm. The new attribute judgement method for hole-mapping cells was considered and an additiv e step after cut phase was employed. These improvements were found to be effectiv e, and the modified algorithm was extended to the application of self-adapted g r id and DRAGON grid generation. Several complicated examples were also included t o demonstrate that this algorithm becomes more stable, more automatic, and also more suitable in large applications.