Measuring Large Scale Flow Structures Behind a Bluff Body Using a Hot-wire Rake

Abstract

Wake behind a D-shaped bluff body were studied using experimental method. The forcing amplitude was Cμ = 0.1%. A rake of 14 hot-wire probes were used to measure the instantaneous velocity at different stream-wise position simultaneously. It was found when two actuators act in phase at a forcing frequency S tA of 0.16, the anti-symmetric motion (mode 1) in the wake was suppressed and the periodic changes in the size of the separation bubble (mode 2) were promoted.