Passive and Active Controls of Three-Dimensional Wake of Bluff-Body(<Special Issue>Advanced Fluid Information)

Passive and active controls of wakes behind axisymmetric bluff-bodies are presented. The passive controls include base-bleed (slotted disks), edge-induced longitudinal vortices behind three-dimensional polygonal plates, the fineness ratio and surface protrusion. The disk wake was further actively controlled in air using actuated tabs and in water using net-zero mass actuators along the edge. The active control suppressed the helical mode of oscillation, but enhanced the closing of the reverse flow region with reduced base pressure. Unsteady velocity vector fields from the time-resolved PIV are presented and issues related to future feedback flow control for the bluff-body wake will be addressed.