Theodoros Michelis

Cylinder in the vicinity of a bluff body leading edge

Time resolved PIV measurements are performed on a cylinder (D = 20mm) placed in proximity to the leading edge of an elongated bluff body (� = R/t = 0.3) at ReD = 2.6 × 10 4 . Three gap-to-cylinder diameter ratios (G/D) are selected (0.25, 0.75, 1.25) for two streamwise positions. For each streamwise position the bluff body leading edge separation bubble is either promoted or prevented by the presence of the cylinder which shifts the relative position of favorable pressure gradient regions. The StD of the cylinder shedding is reduced when the separation bubble is eliminated as the latter causes blockage that reduces the effective cylinder diameter. POD analysis captures both shedding and low frequency flapping associated to the separation bubble and revealed that the bubble shedding becomes phase locked to the cylinder shedding.