# Analysis of a Novel Fluidic Oscillator under Several Dimensional Modifications
## 6 Results
### Outlet Width Modification  
In the present subsection, the same flow parameters previously evaluated as a function of the Reynolds number will now be analyzed for several outlet widths (six in total) initially defined in Table 3. Notice that in the present section the Reynolds number is kept constant at Re = 54,595. As previously performed for different Reynolds numbers, Figure 12 introduces the FO and FC unsteady mass flows for the smallest (outlet 1), largest (outlet 6), and standard (STD) outlet widths evaluated in the present study. As expected, the FO outlet mass flow average value remains constant, and the incoming flow has a constant Reynolds number. However, the peak-to-peak amplitude drastically grows with the outlet width; in fact, the FO outlet mass flow amplitude grows by 286% when comparing the largest (outlet 6) and smallest (outlet 1) widths evaluated (Figure 12a). It appears that the FO outlet mass flow amplitude is linked with the degree of freedom the jet has inside the MC. The FO oscillation frequency reduces by 10% with the outlet width increase; it went from 14.8 Hz in (outlet 1) to 13.33 Hz in (outlet 6). In fact, considering that the mass flow entering the FO remains constant, a reduction in frequency is to be expected when increasing the oscillation amplitude. On the other hand, the FC mass flow (see Figure 12b) appears to be rather unaffected by the outlet width modifications tested, the FC mass flow average value and peak-to-peak amplitude and frequency suffer negligible changes of less than 0.5% when comparing the maximum and minimum outlet widths studied. At this point, we conjecture that the rather constant FC mass flow, could be due to a constant pressure drop between the respective feedback channels inlet and outlet sections. Perhaps it is very relevant to highlight that the FC mass flow is not always flowing from the FC inlet towards the FC outlet, but there is an even larger instantaneous reverse flow  
Figure 11: Fluidic oscillator internal velocity magnitude field (**a**,**c**) and pressure field (**b**,**d**). Minimum Reynolds number \(Re=27\),483 (**a**,**b**), and maximum Reynolds number \(Re=68\),707 (**c**,**d**). Figure 12: Fluidic oscillator outlet unsteady mass flow (**a**) and feedback channel mass flow (**b**) for the smallest (outlet 1), largest (outlet 6) and standard (STD) outlet widths evaluated. (flow going from the FC outlet towards the FC inlet). This large reverse flow is more clearly seen in the velocity field videos presented in the appendix as Supplementary Materials, and it seems to be a particular characteristic of the present FO configuration. Notice that the wide and short FC paths enhance the traveling of the fluid particles in both FC directions. On the other hand, the MC inlet width chosen for the present FO configuration appears to be rather small and so it favors the existence of reverse flow. It is also relevant to highlight the existence of flow asymmetry on both the FO outlet and FC mass flows. When the FO outlet mass flow reaches its maximum, the peak is rather scattered, as if the fluid was trembling, but when the FO outlet mass flow reaches its minimum, which happens when the FO outlet mass flow flows quite horizontally, the reverse flow in one of the FC and the direct flow in the other FC are both at the maximum. Under these conditions, the FO outlet mass flow presents rather a smooth minimum peak. In reality, the FO outlet mass flow trembling is generated when the reverse feedback channel mass flow reaches the FC inlet and interacts with the main jet flowing inside the MC. This interaction happens exactly a quarter of a cycle after the instant at which the reverse FC mass flow is at the maximum and corresponds to the time needed by the FC mass flow to travel from the FC inlet to the FC outlet. When these two jets flows interact, the stagnation pressure at the MC converging walls suffers a huge fluctuation which affects the entire domain, also generating the trembling on the FO outlet mass flow.