## 5 Results  
### Modifying the (Mc) Inlet Width  
The first modification to be considered is the variation of the mixing chamber inlet width. Figure 3 introduces the variation of (FO) output mass flow peak to peak amplitude and frequency as a function of the different inlet widths evaluated. The first thing to notice is that whenever the inlet width falls below a minimum or is higher than a maximum value, the actual (FO) is not producing any outgoing frequency, see Figure 3a. The explanation why there is no flow oscillation when the actuator inlet width falls to a minimum, is based on the fact that, the mixing chamber incoming jet borders impinge onto the feedback channels (FC's) outlet internal vertical walls, creating a flow stream in the (FC's) which goes from left to right, from upstream to downstream, and along both (FC's) at the same time. At both (FC's) outlet internal vertical walls, a stagnation pressure point is generated, from this point, pressure waves are generated and sent from the feedback channels outlets to the inlets. The combination of these two effects prevents any feedback flow to move from downstream to upstream. On the other hand, when the mixing chamber inlet width is too large, a gap appears between the incoming jet and the mixing chamber inlet width borders. This small gap is enough to prevent a pressure increase at the (FC's) outlets, then it allows the fluid coming up from the (FC) inlet, to escape through this gap towards the mixing chamber. In Figure 3b, is presented the effect of modifying the inlet width on the (FO) outlet mass flow peak to peak amplitude. As previously presented, for inlet widths exceeding a limit in any direction, whether too big or too small, the flow stops oscillating and the amplitude decays to zero. For the intermediate values it is seen that the amplitude is initially being highly affected by the inlet width, but as the width keeps increasing the amplitude decreases. It is also seen that the amplitude tendency is opposed to that of the frequency, small frequencies are linked with high oscillation amplitudes and vice versa. The reason why this is happening, it is clearly seen when applying the mass conservation equation between the (FO) inlet and outlets. For the present modification, when high widths are considered, the jet entering the mixing chamber (MC), suffers a relatively small oscillation inside the mixing chamber (MC), causing a small variation of amplitude at the oscillator exit. As the mixing chamber (MC) inlet width decreases, the jet oscillation amplitude inside the mixing chamber increases, the jet deflection angle at the mixing chamber inlet and outlet also increases and so does the fluidic oscillator output amplitude, see Figures 3-5. Based on the results presented in Figure 3, it can also be stated that the effects on output frequency and amplitude, are more relevant as the Reynolds number increases, but the trend already presented remains the same. The threshold at which the oscillation stops, appears to be rather independent of the Reynolds number. Figure 4 introduces the flow field and pressure distribution inside the (FO), for the minimum and maximum (MC) inlet widths at which oscillation still appears, the Reynolds number is 16034. For the maximum inlet width, Figure 4a,c, the jet bending inside the (MC) is supported by the low pressure below the jet generated by the Coanda effect, see Figure 4c, at the external chamber the jet flows reattached to the surface of the wedge, generating two alternative vortices of nearly the same size on both sides of the external chamber. From Figure 5a, it is observed that no reverse flow appears at the (FO) upper outlet, see the curve characterizing the highest inlet width. Regarding the pressure distribution, the pressure is very much the same along the entire (MC), very small pressure fluctuations appear on the (FC's), alternatively pressurizing one (FC) or the other.