Control of Flow Past Bluff Bodies Using Rotating Control Cylinders

Mittal, Sanjay

doi:10.1006/jfls.2000.0337

Cited by 95 publications

(33 citation statements)

References 37 publications

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“…This transition from an unsteady flow to a steady one when the rotation parameter is increased to ξ > 3 is consistent with the symmetric streamlines in the wake shown in figure 6. Mittal (2001), in a similar configuration, but with smaller control cylinders having diameters of D/20, observed that the Re D = 100 flow is stabilized for ξ > 4.…”

Section: Wake Stabilizationmentioning

confidence: 80%

“…In contrast, rotating the control cylinders above a critical rate stabilized the wake. The ability of rotating cylinders to stabilize the wake of a main cylinder, especially at low Reynolds numbers, has been shown by Mittal (2001) and Muddada & Patnaik (2010). Figure 6 compares instantaneous simulation streamlines from the numerical simulations with those from corresponding potential flow models.…”

Section: Wake Stabilizationmentioning

confidence: 96%

“…In the application of rotating control cylinders to bluff body flow control, Mittal (2001) found that the gap between the main and control cylinders is a critical parameter and sensitivity to the gap changes with Reynolds number. Mittal (2003) suggests that the mechanism of the control is the injection of momentum from the outer flow into the wake and therefore the circulation of the control cylinders is of primary importance.…”

Section: Introductionmentioning

confidence: 99%

“…Modi (1997) reports the results of numerous studies in this Reynolds number range for airfoils and non-circular cylinders. The highest Reynolds number studies for the drag reduction of a circular cylinder are the experiments by Korkischko & Meneghini (2012) up to Re D = 7500 and the numerical simulations by Mittal (2001) at Re D = 10, 000, who noted that the two-dimensional results should be considered an upper bound for the lift of a rotating cylinder in three-dimensional flow. It is therefore important to demonstrate drag reduction at higher Reynolds numbers in experiment or three- …”

Section: Introductionmentioning

confidence: 99%

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Flow control with rotating cylinders

et al. 2017

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We study the use of small counter-rotating cylinders to control the streaming flow past a larger main cylinder for drag reduction. In a water tunnel experiment at a Reynolds number of 47, 000 with a three-dimensional and turbulent wake, Particle Image Velocimetry (PIV) measurements show that rotating cylinders narrow the mean wake and shorten the recirculation length. The drag of the main cylinder was measured to reduce by up to 45%. To examine the physical mechanism of the flow control in detail, a series of two-dimensional numerical simulations at a Reynolds number equal to 500 were conducted. These simulations investigated a range of control cylinder diameters in addition to rotation rates and gaps to the main cylinder. Effectively controlled simulated flows present a streamline that separates from the main cylinder, passes around the control cylinder, and reattaches to the main cylinder at a higher pressure. The computed pressure recovery from the separation to reattachment points collapse with respect to a new scaling, which indicates that the control mechanism is viscous.

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Section: Wake Stabilizationmentioning

confidence: 80%

Section: Wake Stabilizationmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow control with rotating cylinders

et al. 2017

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“…The measurements of mean drag demonstrate that these con gurations do not reduce the mean drag coe cients as much as reported experimentally by Korkischko & Meneghini (2012) and with numerical simulation by Mittal (2001). A considerable reduction of the mean drag coe cient was achieved when the eight control cylinders are xed (U c /U = 0).…”

Section: Resultssupporting

confidence: 63%