## 4 Results and Discussion
### Discussion  
Figure 17 presents the optimal total error ratios of the two trailing edge shapes and the corresponding calculation accuracy improvements. The sharp trailing edge performs better than the blunt trailing edge; in order, the accuracy improvements are 98.66%, 24.99%, 22.44%, 12.60%, 10.44%, and 12.25%. Therefore, the influence of the trailing edge shape on the calculation accuracy decreases as the AOA range increases, except at the range of (0\({}^{\circ}\), 10\({}^{\circ}\)). For the sharp trailing edge adopting NACA4 and the definition formula, when the AOA ranges are (0\({}^{\circ}\), 0\({}^{\circ}\)), (0\({}^{\circ}\), 8\({}^{\circ}\)), and (0\({}^{\circ}\), 10\({}^{\circ}\)), the definition formula is preferred and the accuracy improvements are 94.61%, 2.02%, and 8.97%, respectively. Conversely, when the AOA ranges are (0\({}^{\circ}\), 2\({}^{\circ}\)), (0\({}^{\circ}\), 4\({}^{\circ}\)), and (0\({}^{\circ}\), 6\({}^{\circ}\)), the NACA4 is preferred. Therefore, the choice of NACA4 and formula depends on the studied range of AOA. Furthermore, regarding the influence of the number of data points adopted in the definition formula on the simulation accuracy, Figure 18 presents the optimal total error ratios and the calculation accuracy improvements. From the 132 points provided by Airfoil Tools, when the data points doubled to 264 points, the accuracy improvements were 40.79%, \(-\)0.19%, 0.03%, \(-\)0.17%, \(-\)0.35%, and 0.24%, respectively. At the ranges of (0\({}^{\circ}\), 0\({}^{\circ}\)), (0\({}^{\circ}\), 4\({}^{\circ}\)), and (0\({}^{\circ}\), 10\({}^{\circ}\)), the error ratios dropped but the declines in the latter two were very small. At the ranges of (0\({}^{\circ}\), 2\({}^{\circ}\)), (0\({}^{\circ}\), 6\({}^{\circ}\)), and (0\({}^{\circ}\), 8\({}^{\circ}\)), the error ratios increased. Therefore, for  
Figure 17: The optimal total error ratios of two shapes trailing edge and the corresponding calculation accuracy improvements. the 132 points provided by Airfoil Tools, except at the range of (0\({}^{\circ}\), 0\({}^{\circ}\)), the increase in the amount of data does not result in significant optimization of computational accuracy. For the 200 points provided by NACA4, as the data number doubled to 400 points, except at the ranges of (0\({}^{\circ}\), 0\({}^{\circ}\)) and (0\({}^{\circ}\), 2\({}^{\circ}\)), the error ratios dropped; the calculation accuracy improvements were 1.45%, 2.56%, 4.41%, and 5.46%. When the AOA range increased, the optimization effect brought by increasing the number of data points also increased. It should be noted that at the range of (0\({}^{\circ}\), 0\({}^{\circ}\)), the optimal total error ratios are very small, at 0.003% and 0.049%, respectively. The ratio 0.049% still increased more than 100% compared to 0.003%, so the related accuracy improvement is described as \"-big\" in Figure 13. According to the best results under different AOA ranges, which are highlighted in red in Figure 13, the 200 points formula is preferred at the ranges of (0\({}^{\circ}\), 0\({}^{\circ}\)) and (0\({}^{\circ}\), 2\({}^{\circ}\)), while the 400 points formula is preferred at the ranges of (0\({}^{\circ}\), 4\({}^{\circ}\)), (0\({}^{\circ}\), 6\({}^{\circ}\)), (0\({}^{\circ}\), 8\({}^{\circ}\)), and (0\({}^{\circ}\), 10\({}^{\circ}\)). In short, the performance of the 200 points data is superior to that of the 132 points. For the 132 points, the number of data points is not directly correlated with calculation accuracy. For the 200 points, under the condition of a high AOA range, increasing the number of data points can improve the calculation accuracy. Figure 19 presents the optimal total error ratios of three far-field distances and the corresponding calculation accuracy improvements. As the far-field distance rises from 12 \(L\) to 16 \(L\), except at the ranges of (0\({}^{\circ}\), 0\({}^{\circ}\)) and (0\({}^{\circ}\), 2\({}^{\circ}\)), where the error ratios increase, the simulation accuracy increased by 2.78%, 9.01%, 12.44%, and 14.15%, respectively.