*5.1. Grid Conver*

Grid-convergence index (GCI) analyses based on Richardson extrapolation [34] were performed to evaluate the grid dependency of the numerical results. Table 2 shows the results of the GCI analysis for the jet frequency in the internal domain of the fluidic oscillator. The relative discretization error (GCI <sup>21</sup> fine) of the finally selected grid with 4.7 × 105 cells (N1) was 0.957%. The results of the GCI analysis for the lift coefficient in the external domain are shown in Table 3. The grid with 3.8 × 106 cells was selected in this domain, including internal domains of the fluidic oscillators with a GCI <sup>21</sup> fine of 0.072%. The grid selected in Table 3 was also used in each oscillator included in the domain shown in Figure 2.


**Table 2.** Grid-convergence index (GCI) analysis for the internal domain of a fluidic oscillator.

**Table 3.** Grid-convergence index(GCI) analysis for the external domain of airfoil with fluidic oscillator.

