An experimental investigation of the use of isoparametric and rational basis elements in a fluid flow problem

Three competing finite element techniques are applied to a simple flow problem in a region with curved boundaries. Only three-sided elements are considered. The techniques are (1) straight-sided elements, (2) isoparametric elements, both of which use polynomial bases, and (3) curved elements using rational basis functions. The broad conclusions are that both curved-edge techniques are much superior to their straight-sided equivalent and that rational basis functions are quite successful in practice but require slightly more effort to implement, and cost a little more in computer time. From the point of view of efficiency, isoparametric elements seem to be the best choice.