On the Stability and Accuracy of the Spectral Difference Method

In this article, it is shown that under certain conditions, the spectral difference (SD) method is independent of the position of the solution points. This greatly simplifies the design of such schemes, and it also offers the possibility of a significant increase in the efficiency of the method. Furthermore, an accuracy and stability study, based on wave propagation analysis, is presented for several 1D and 2D SD schemes. It was found that higher than second-order 1D SD schemes using the Chebyshev-Gauss-Lobatto nodes as the flux points have a weak instability. New flux points were identified which produce accurate and stable SD schemes. In addition, a weak instability was also found in 2D third- and fourth-order SD schemes on triangular grids. Several numerical tests were performed to verify the analysis.