Comparison of different strategies for conversion of triangular mesh into quadrilateral mesh

EM simulation of complex CAD models, described by a quadrilateral mesh, using higher order method of moments offers significant benefits in terms of computational efficiency. In order to exploit these benefits, a robust algorithm for automatic generation of a well-structured quadrilateral mesh is needed. The paper gives new variants of algorithm for quadrilateral meshing, which starts from triangular mesh obtained by a well developed triangular meshing algorithm, then eliminates excess details, and finally re-meshes triangles into quadrilaterals. Three new strategies of merging neighbouring triangles into quadrilaterals are proposed, based on: a) angle based criterion (ABC), b) shaped quality factor criterion (SQFC), and differential SQFC (DSQFC). Robustness of different strategies is investigated on example of Apache helicopter CAD model, giving slight advantage to DSQFC.