# Novel Fluidic Oscillator Evaluation Considering Dimensional Modifications
## 1 Introduction
The origin of the forces driving the self-sustained oscillations was investigated in [PERSON] and [PERSON] [22], where a comprehensive analysis of the forces acting on the jet at the mixing chamber entrance was performed. In a further study [23], they analyzed the FO output frequency variations under several MC design modifications. In the experimental study performed by [14], modifications of the mixing chamber inlet and outlet widths as well as the FO outlet width were considered. It was observed that the jet spreading angle and its oscillating frequency were proportional to the MC inlet width. If the inlet width was too small, no oscillating frequency was generated. The mixing chamber outlet width was seen to control the size of the recirculation bubble, which partially controlled the jet spreading angle. The FO outlet width was responsible for the MC's internal pressure and partially controlled the recirculation bubble in the MC. In a second paper [35], they created a novel master-slave fluidic oscillator design capable of producing adjustable spreading angles from 0 to 100\({}^{\circ}\). The output frequency and spreading angle increased with the master FO flow rate. This new configuration allowed dynamic adaptation to different working conditions and impinging targets. The internal geometric parameters of a novel FO configuration capable of generating small pulsating frequencies \(\mathcal{O}\)10 Hz was assessed in [25]. A large number of internal dimensions, until finding the limits of the self-sustained oscillations, were studied, and it was realized that the width of the FO had a large impact on the outlet frequency. In the research undertaken by [36], movable feedback channels and resonators placed on both sides of an FO were numerically evaluated using the \(k-\omega\) SST and LES turbulence models. The modification of the FC length had little effect on the oscillation frequency, but when the feedback channel length increased relative to the resonator length, the FO outlet frequency had a sharp increase. An equation capable of determining the output frequency as a function of the resonator's dimensions was obtained. The heat transfer effect of an oscillating jet coming out from an FO and impinging on a flat plate was recently studied by [9; 10; 11]. In [11], eight different fan-shaped exit configurations, with angles ranging between 0 and 130\({}^{\circ}\), were evaluated. In this paper, it was realized that the output frequency was independent of the fan-shaped angle, but the heat transfer deteriorated with an increase in the fan angle. For fan angles exceeding 70\({}^{\circ}\) the jet was no longer attached to the outlet walls, although a particularly good cooling uniformity was observed under these conditions. In [10], the heat transfer effect was evaluated when scaling the FO while keeping the outlet throat constant. The jet frequency increased and the heat transfer rate decreased when decreasing the scale factor. They correlated the jet frequency with the evolution of the separation bubble in the MC, obtaining a new definition of the Strouhal number, which remained constant for different scaled geometries. In the experimental work performed by [9], the MC length, FC cross-sectional area, and the FO's nozzle-to-plate distance were modified. The main effect of reducing the MC length was that the twin-jet structure turned into a single jet. As in [25], it was noted that the oscillation stopped once dimensional modifications exceeded a certain threshold. When reducing the FC's minimum width, the jet oscillation amplitude decreased and the frequency increased. Several geometry modifications and scale variations of a particular shaped FO were evaluated by [37] in order to enhance flow mixing. The research was mostly performed using 2D-CFD simulations; comparisons with experimental results and three-dimensional CFD simulations were also presented. They defined which were the most relevant design parameters, opening a door to future design modifications.