Active control and drag optimization for flow past a circular cylinder
Journal of Computational Physics
Flow Visualization and PIV Measurement of Flow Field around a Darrieus Rotor in Dynamic Stall
Journal of Visualization
Phase Averaged Velocity Field in the Near Wake of a Square Cylinder Obtained by a PIV Method
Journal of Visualization
Numerical Analyses of Flow around Airfoils Subjected to Flow Induced Vibration
Journal of Visualization
Visualization of Aerodynamic Noise Source in the Wake of a Rotating Cylinder
Journal of Visualization
Visualization Study on Suppression of Vortex Shedding from a Cylinder
Journal of Visualization
Vortex formation in a viscoelastic entry flow of asymmetric planar contraction
Journal of Visualization
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The flow field around a rotationally oscillating circular cylinder in a uniform flow is studied by using a particle image velocimetry to understand the mechanism of drag reduction and the corresponding suppression of vortex shedding in the cylinder wake at low Reynolds number. Experiments are conducted on the flow around the circular cylinder under rotational oscillation at forcing Strouhal number 1, rotational amplitude 2 and Reynolds number 2,000. It is found from the flow measurement by PIV that the width of the wake is narrowed and the velocity fluctuations are reduced by the rotational oscillation of the cylinder, which results in the drag reduction rate of 30%. The mechanism of drag reduction is studied by phase-averaged PIV measurement, which indicates the formation of periodic small-scale vortices from both sides of the cylinder. It is found from the cross-correlation measurement between the velocity fluctuations that the large-scale structure of vortex shedding is almost removed in the cylinder wake, when the small-scale vortices are generated at the unstable frequency of shear layer by the influence of rotational oscillation.