The effects of an upstream cylinder on the wake behind a downstream cylinder were investigated in turbulent flow using two-dimensional particle image velocimetry (2D PIV). Analyzing the small scale fluid interactions between two elements serves as a unit of measurement for engineering applications on a larger scale, such as random distributions of multiple roughness elements. To generate 31 experimental configurations, the streamwise spacing (L/d = 2, 6, 12), spanwise offset (w/d = 0, 0.25, 0.5, 1, 2), and height ratio (h1/h2 = 0.5, 1, 1.5) of the upstream cylinder were varied relative to the downstream cylinder. Manufactured from clear acrylic and mounted onto acrylic plates, cylinders were arranged in the 0.2 x 0.2 x 2 m3 Union College water channel. With an incoming flow velocity of 0.949 m/s and Reynolds number Re = 5923, immersion in a turbulent boundary layer was maintained using bars as trip elements. The introduction of a spanwise offset in this study produced different results depending on the streamwise spacing and height ratio. While the majority of offset cases increase the amount of recirculating flow behind the downstream cylinder, cases with L/d = 6 and h1/h2 = 1 reduce recirculation as the offset increases. With an increase in streamwise spacing, flow recirculation occurs at a greater height. Lower height ratios, such as h1/h2 = 0.5 are more susceptible to changes in spanwise offset, as w/d = 1 and w/d = 2 yield recirculation zones with the lowest heights.
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