INVESTIGATION OF VORTICITY CHARACTERISTICS IN THE WAKE REGION OF AN ECCENTRICALLY EMBEDDED CYLINDER IN A RECTANGULAR CHANNEL

The present work experimentally investigates the complex patterns associated with the vorticity dis-tributions in the wake region of a cylinder placed in a rectangular channel with its axis offset from the channel centerline. The experiments are carried out for three different cylinder diameters giving a blockage ratio (β) of 0.25, 0.38, and 0.5 and the resulting gap ratios (γ) of 0.83, 0.38, and 0.17 over a range of Reynolds number 100 ≤ Re ≤ 300. The vorticity patterns observed from particle image velo-cimetry measurements suggest that the transition from a steady flow laminar regime to the initiation of turbulence occurs in five distinct stages. The wall proximity is observed to play a crucial role in this transition and it imparts stability, delays, and extends the range within which this transition oc-curs. However, at a very low spacing corresponding to γ = 0.17, the vortex shedding initiation is not observed to occur even at Re = 300.