# Novel Fluidic Oscillator Evaluation Considering Dimensional Modifications
## 6 Results
### Feedback Channel Dimensional Modifications (2D-CFD)
This information is summarized in Figure 18d; note that regardless of the dimensional modification considered, the frequency decreases with the FC time-averaged reverse mass flow increase, with the exception of the maximum FC width studied. Note that the FC reverse mass flow is taken as positive in Figure 18d. For this particular case, there was a quite random oscillation of the main jet inside the MC. When considering all the results obtained in the 2D-CFD simulations, with the exception of the point characterizing the maximum FC width case, the FO outlet mass flow frequency can be estimated as a function of the FC time-averaged reverse mass flow, according to the equation \(f(Hz)=114,321.23899\times(Rf)^{2}-2329.3142\times(Rf)+34.1836\), with \((Rf)\) being the time-averaged FC reverse mass flow, which is taken as positive. The coefficient of determination was \(R^{2}=0.9316\). It therefore can be concluded that for the present FO configuration, the evaluation of the FC time-averaged reverse mass flow allows for estimation of the FO outlet frequency. Figure 17: Feedback channel outlet net pressure forces (**a**) and net mass flow forces (**b**) as a function of the different feedback channel widths evaluated. For the four FC widths evaluated, the time-dependent stagnation pressure at the MC's lower converging wall, and its time-averaged value and peak-to-peak amplitude are, respectively, presented in Figure 19a,b. As the FC width increases, the peak-to-peak amplitude oscillation grows until reaching the maximum FC width, where the amplitude decreases and the oscillation becomes more random due to the large degrees of freedom of the MC internal jet under these conditions. In Figure 19c,d, the time-dependent force, its time-averaged value, and the associated peak-to-peak amplitude at the FC lower outlet due to the fluid pressure and for the four FC widths considered is shown. The force appears to linearly increase with the FC width, but in reality this linear increase is due to the FC width increase; then, the average pressure at the MC's converging walls shows a minor variation for the different FCs considered. The pressure force's peak-to-peak amplitude also grows with the FC width. It is relevant to highlight that, especially for the FC4 case, the pressure force curve is particularly scattered, which obeys to the highly random fluctuations associated with this maximum FC width. The evolution of the time-dependent mass flow force and its time-averaged and peak-to-peak amplitude at the FC lower outlet are shown in Figure 19e,f. The mass flow force follows the same trend as the FC lower outlet mass flow (Figure 18c), the mass flow force's average value and peak-to-peak amplitude grow with FC width. The time-dependent overall force acting on the jet as it enters the MC, as well as its peak-to-peak amplitude, is introduced in Figure 19g,h. The amplitude considerably grows when going from FC1 to FC2, but remains rather constant for the rest of the FC widths evaluated. Note as well that for the FC4 case the net force curve is particularly scattered, following the trend shown by the time-dependent stagnation pressure measured at the MC's lower converging wall (Figure 19a). Figure 18: Fluidic oscillator outlet mass flow (**a**), its associated frequency (**b**), and the lower feedback channel outlet mass flow (**c**) as a function of the different feedback channel widths evaluated. Fluidic oscillator outlet mass flow frequency as a function of the feedback channel time-averaged reverse mass flow (**d**).