Abstract: The preprocessing methods of unstructured grids arc one of the important technologies for unstructured grids CFI)parallel computing. The paper supplied a new efficient and robust fast search algorithm to build the relation- ship graph of the global unstructured cells,which is based on buffer data structure and can be easily implemented with low complexity. And the paper brought forward the reordering algorithm to deal with the out of-order problem brought by unstructured grids,which can improve the computing efficiency and can be used in all kinds of unstructured grids. Experiment results show that even in the case of complicated areas of large grids number, the pre-processing methods can get good performance.

Key words: Unstructured grids, CFD parallel computing, Preprocessing, Fast Search Algorithm, Reordering