Investigation and enhancement of cut-paste algorithm in overlapping grid

To solve the problem in generation of overlapping grids in CFD (computational fluid dynamics) automatically, the main characteristics and basic flow of the newly emerged cut-paste algorithm which generates overlapping grids by cutting and pasting hole fronts were investigated. The promising advantages of this algorithm were introduced, yet two main disadvantages were putted forth. In the conventional algorithm, one may gets failed in the judgement of attributes of 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. Enhancements were made on these aspects to improve this algorithm. The new attribute judgement method for hole-mapping cells was considered and an additive step after cut phase was employed. These improvements were found to be effective, and the modified algorithm was extended to the application of self-adapted grid and DRAGON grid generation. Several complicated examples were also included to demonstrate that this algorithm becomes more stable, more automatic, and also more suitable in large applications.