Passive jet control of flow around a circular cylinder

and suppressing fluctuating amplitude of the dynamic wind loads acting on the test model. With 24 suction/jet holes evenly distributed over the cylindrical test model (i.e., the N13 design of the present study), the passive jet control method was found to be able to achieve up to 33.7 % in drag reduction and 90.6 % in fluctuating wind loading suppression, in comparison with the baseline case. The PIV measurement results revealed clearly that the passive jet control method would cause airflow jets into the cylinder wake and change the shedding modes of the wake vortex structures from the cylindrical test model. Because of the dynamic interactions between the passive jets and the wake vortex structures, the antisymmetric pattern of the wake vortex shedding was found to be converted to symmetric mode. The periodicity of the vortex shedding was also observed to be diminished and eventually disappeared with the number increase in the suction/jet holes. A linear stability analysis was performed to suggest that the passive jet flow would modify the wake stability of the circular cylinder by decreasing the disturbance growth rate in the immediate wake and pushing the region of absolute instability further downstream.