Abstract
Flow around a circular cylinder controlled using plasma actuators is investigated by means of direct numerical simulation (DNS). The Reynolds number based on the freestream velocity and the cylinder diameter is set atReD=1000. The plasma actuators are placed at±90° from the front stagnation point. Two types of forcing, that is, two-dimensional forcing and three-dimensional forcing, are examined and the effects of the forcing amplitude and the arrangement of plasma actuators are studied. The simulation results suggest that the two-dimensional forcing is primarily effective in drag reduction. When the forcing amplitude is higher, the mean drag and the lift fluctuations are suppressed more significantly. In contrast, the three-dimensional forcing is found to be quite effective in reduction of the lift fluctuations too. This is mainly due to a desynchronization of vortex shedding. Although the drag reduction rate of the three-dimensional forcing is slightly lower than that of the two-dimensional forcing, considering the power required for the forcing, the three-dimensional forcing is about twice more efficient.
Highlights
Flow around a bluff body causes a significant amount of drag
As an example of active control of flow around a bluff body, Kim and Choi [7] performed a numerical simulation of a flow around a circular cylinder at ReD = U∞D/] = 100 − 3900 controlled by using blowing and suction and attained more than 20% drag reduction
In the present study, we investigate the flow around a circular cylinder controlled using plasma actuators by means of direct numerical simulation (DNS)
Summary
Flow around a bluff body causes a significant amount of drag. In addition, the vortices shed from the bluff body cause flow-induced noise; the resulting lift fluctuations may damage instruments. Bhattacharya and Gregory [13] experimentally examined three-dimensional forcing at ReD = 4700 In their three-dimensional forcing, the plasma actuators inducing streamwise flows are placed on a circular cylinder periodically in the spanwise direction with the wavelength of λ = 4D. In both studies, a better drag reduction effect than that by two-dimensional forcing was obtained. In the present study, we investigate the flow around a circular cylinder controlled using plasma actuators by means of direct numerical simulation (DNS) We consider both the two-dimensional forcing and the three-dimensional forcing and investigate the effect of forcing amplitudes on the flow modifications
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