Naturally Separated Turbulent Flow Around Two Cylinders in Tandem at High Reynolds Number by Time-Resolved PIV

In this study the focus is made on the properties of the bistable flow between two cylinder in tandem for a pitch ratio L/D = 3.7 at a Reynolds number of 132,800. Time resolved particle image velocimetry (TRPIV) is used to measure the spatial distribution and time fluctuations of the velocity field in the wake of the upstream cylinder. From velocity spectra and statistics fields, the existence of two distinct seemingly stable flow patterns is shown, having different spatial structures and predominant frequencies.