Quadrilateral approaches for accurate free mesh method

This paper presents the formulation of free mesh method and two approaches of the method by incorporating quadrilateral elements. The approaches do no t have any difference with the original free mesh method in their fundament al algorithms, wherein local system equations with triangular elements are created nodewise to create the global system equations, and their implement ation is therefore very easy. The first approach creates quadrilateral elem ents inside every triangular element, whilst quadrilateral elements are gen erated outside every triangular element in the second approach. The results of numerical examples indicate that the approaches improve the accuracy of free mesh method, further opening the possibility for more improvement usi ng an accurate quadrilateral element. Copyright (C) 2000 John Wiley & Sons, Ltd.