Numerical investigation of passive flow control around a D-shaped bluff body

A passive flow control around a two-dimensional D-shaped bluff body is studied at a Reynolds number of 13 000 using large eddy simulation with the Coherent Structure Model (CSM). A small circular control cylinder located in the near wake region behind the bluff body is employed as a local disturbance of the shear layer and the wake. Numerical results are compared with experimental data in detail, including global flow paramters of drag coefficient as well as mean and RMS velocities. The predictions suggest that the bubble recirculation length is significantly increased by the local disturbance of the small cylinder. A drag reduction of about 27.6% is observed in the numerical simulation. The small control cylinder was found to split the shear layer detached from the main bluff body and result in the flow structure like a jet which inflates the formation of the wake region behind the main bluff body