809 Study on the Mechanism of Drag Reduction of a Circular Cylinder by Rotational Oscillation

2000 ◽  
Vol 2000 (0) ◽  
pp. 227-228
Author(s):  
Tomokazu SUZUKI ◽  
Nobuyuki FUJISAWA
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Rotational Oscillation

scholarly journals Drag Reduction of a Circular Cylinder. 1st Report, Flow Control Using a Small Rod.

1994 ◽  
Vol 60 (573) ◽  
pp. 1554-1560 ◽  
Author(s):  
Tamotsu Igarashi ◽  
Takayuki Tsutsui ◽  
Hirochika Kanbe
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Flow Control

Drag reduction of circular cylinder using linear and sawtooth plasma actuators

2021 ◽  
Vol 33 (12) ◽  
pp. 124105
Author(s):  
Longjun Wang ◽  
Md. Mahbub Alam ◽  
Yu Zhou
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Plasma Actuators

Drag Reduction of the Flow Past a Circular Cylinder in Surfactant Solution

2001 ◽  
Author(s):  
Satoshi Ogata ◽  
Keizo Watanabe
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Sodium Salicylate ◽  
Tap Water ◽  
Pressure Coefficient ◽  
Surfactant Solution ◽  
Reduction Ratio ◽  
Number Range ◽  
Surfactant Solutions ◽  
Maximum Drag Reduction

Abstract The flow around a circular cylinder in surfactant solution was investigated experimentally by measurement of the pressure and velocity profiles in the Reynolds number range 6000 < Re < 50000. The test surfactant solutions were aqueous solutions of Ethoquad O/12 (Lion Co.) at concentrations of 50, 100 and 200 ppm, and sodium salicylate was added as a counterion. It was clarified that the pressure coefficient of surfactant solutions in the range of 10000 < Re < 50000 at the behind of the separation point was larger than that of tap water, and the separation angle increased with concentration of the surfactant solution. The velocity defect in surfactant solutions behind a circular cylinder was smaller than those in tap water. The drag coefficients of a circular cylinder in surfactant solutions were smaller than those of tap water in the range 10000 < Re < 50000, and no drag reduction occurred at Re = 6000. The drag reduction ratio increased with increasing concentration of surfactant solution. The maximum drag reduction ratio was approximately 35%.

Optimized drag reduction and wake dynamics associated with rotational oscillations of a circular cylinder

2018 ◽  
Vol 11 (97) ◽  
pp. 4825-4843
Author(s):  
A. Mehmood ◽  
M. R. Hajj ◽  
I. Akhtar ◽  
M. Ghommem ◽  
L. T. Watson ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Rotational Oscillations

Active Control Methods for Drag Reduction in Flow Over Bluff Bodies (Keynote)

2002 ◽  
Author(s):  
Haecheon Choi
Keyword(s):  
Circular Cylinder ◽  
Drag Reduction ◽  
Active Control ◽  
High Frequency ◽  
Free Stream ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Control Methods ◽  
Periodic Forcing ◽  
Time Periodic

In this paper, we present two successful results from active controls of flows over a circular cylinder and a sphere for drag reduction. The Reynolds number range considered for the flow over a circular cylinder is 40∼3900 based on the free-stream velocity and cylinder diameter, whereas for the flow over a sphere it is 105 based on the free-stream velocity and sphere diameter. The successful active control methods are a distributed (spatially periodic) forcing and a high-frequency (time periodic) forcing. With these control methods, the mean drag and lift fluctuations decrease and vortical structures are significantly modified. For example, the time-periodic forcing with a high frequency (larger than 20 times the vortex shedding frequency) produces 50% drag reduction for the flow over a sphere at Re = 105. The distributed forcing applied to the flow over a circular cylinder results in a significant drag reduction at all the Reynolds numbers investigated.

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