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This paper presents an experimental study performed in an aerodynamic channel using hot-wire anemometers and flow visualization by injection of dye in water in a hydraulic channel of the flow on two rigid cylinders placed at several angular positions to the flow, from 0° (side-by-side) to 90° (tandem). The main objective is to analyze the effects of the angular positions on the wake flow and the occurrence of bistability. Signal analysis was performed by means of Fourier and discrete and continuous wavelets transform. Time series of the angle of the flow emanating from the cylinder gap related to the main flow direction were obtained from flow visualization analysis to track the flow mode change in the water flow. Results from the aerodynamic channel showed the presence of bistability only for side-by-side configuration, and some attempts to modify the flow mode for 2.5° and 5° while through the flow visualization the flow mode changes were present for side-by-side and for 2.5° configurations. For the other angles investigated, the presence of a narrow and a wide wake without flow mode changes was observed. The difference between the results for 2.5° suggests that the scales and inertia involved in bistability phenomenon may affect the phenomenon. For 75°, the wide wake is so vigorous that it overwhelmed the narrow wake, displacing it downwards, and increasing the amplitude of the vertical component of the wake compared to smaller angles. The phenomena analyzed can be seen as two-dimensional for all cases, but the presence of vertical components shows that the resulting flow is three-dimensional. Keywords Bistable flow • Flow visualization • Hot wires • Turbulent flow • Wavelets List of symbols a,b Wavelet parameters B e Bandwidth (Hz) CWT Constant wavelet transform (-) d Cylinder diameter (mm) Db20 Daubechies wavelet

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