关键词: 四边形网格, 三角形合并, 前沿边

Abstract: This paper shows a method on the indirect quadrilateral mesh generation based on the triangular mesh.In order to solve the defect of remain triangular elements during combining triangular elements，a detailed algorithm for determining side edges is proposed in this paper.This algorithm determines side edges by the edges contained in the triangular background mesh，swapping or splitting the edges of the background mesh according to the position of edges in background mesh and the situation of front edges.This algorithm can avoid the residues of triangular elements.Finally，a grid example is presented to illustrate the validity of this algorithm.

Key words: quadrilateral mesh, combination of triangular elements, front edge