Feedback control of wall turbulence with wall deformation

Endo, Takahide; Kasagi, Nobuhide; Suzuki, Yuji

doi:10.1016/s0142-727x(00)00046-1

Cited by 72 publications

(60 citation statements)

References 31 publications

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“…For example, in the suboptimal control, Lee et al . [12] analysed the opposition controlled flow field with y + d = 10 to find that wall distributions of dp/dz and dw/dy fluctuations could be used to determine the control input, and in the wall deformation flow control [14,15] the velocity induced by wall motion was set equal to the velocity at the detection plane of the opposition control (with y + d = 10). To provide more realistic wall actuation, dimples were used as an actuator for opposition control numerically [16] and experimentally [17].…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of active flow control for turbulent skin friction drag reduction

Chung

Talha

2011

Physics of Fluids

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The effectiveness of the opposition control method proposed by Choi et al . [H. Choi, P. Moin, and J. Kim, J. Fluid Mech. 262, 75-110 (1994)] has been studied using direct numerical simulations. In this study, the effects of the amplitude and the phase of wall blowing and suction control input were considered separately. It is found that the amplitude of wall blowing and suction as well as the detection plane location played an important role in active control for skin friction drag reduction. By changing the amplitude, a substantial drag reduction was achieved for all detection plane locations considered, and the efficiency of the opposition control was also improved. When the control was effective, the drag reduction was proportional to the wall blowing and suction strength. There existed a maximum wall blowing and suction strength, beyond which the opposition control became less effective or even unstable. Turbulence characteristics affected by various wall blowing and suction parameters were analysed to understand * Corresponding author: Y.M.Chung@warwick.ac.uk the underlying mechanisms for drag reduction. The wall normal velocity and vorticity fluctuations showed a strong correlation with drag reduction.

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Section: Introductionmentioning

confidence: 99%

Effectiveness of active flow control for turbulent skin friction drag reduction

Chung

Talha

2011

Physics of Fluids

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“…Related numerical simulations of wall deflection, using a combination of sensors and deformable wall actuators to manipulate the streamwise vortices in wall-bounded turbulent flows, have been performed by Mito & Kasagi (1996) and showed almost no drag reduction. However, similar numerical experiments by Endo et al (1999) and Kang & Choi (2000) exhibited wall shear stress reductions of 10% and 13-17%, respectively. and Tsao et al (1994) demonstrated an electromagnetically activated microflap actuator that could be deflected to produce an upward velocity in opposition to the wall-normal velocity produced by the streamwise sublayer vortices.…”

Section: Previous Microactuator Approachesmentioning

confidence: 58%

Electrokinetic Microactuator Arrays for Control of Vehicles

Diez-Garcia¹,

Dahm²

2002

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“…The potential large modification of boundary layers and of the overall flow field with the small controlled input made such active devices attractive wherever their installation is feasible. In some Reynolds numbers ranges, drag reduction as high as 20% can be established, albeit after some time has elapsed, as reported by Endo et al [11]. Despite their robustness in hostile environments and little fouling potential, however, complex construction, complex method of attachment, and difficulty of attachment to existing surfaces make their use less attractive.…”

Section: Introductionmentioning

confidence: 74%

CFD modeling of turbulent boundary layer flow in passive drag-reducing applications

Bourisli

Al-Sahhaf

2008

Advances in Fluid Mechanics VII

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In this paper, the turbulence boundary layer, velocity and skin friction coefficient characteristics of grooved surfaces are studied. Flow over surfaces with transverse square, triangular and semicircular grooves are numerically modeled via the finite volume method. Comparisons are made on the basis of the grooved surfaces' skinfriction coefficient, normalized by that of a smooth surface, with Reynolds number in the vicinity of 2 × 10 6 . Results show that square grooves are superior to the two other groove geometries in reducing the drag. Viscous damping in all grooves keeps skin friction inside them well below the surface above. However, the interior geometry of square grooves allows them to balance the net inward momentum due to the sudden absence of the wall in a way that minimizes disturbance of the main flow while taking advantage of the restart of the boundary layer. As a consequence to the separation of the boundary layer, an inevitable stagnation point within the groove must exist. Square grooves had the highest such stagnation point along the backward-facing side of the groove. The shortness of the resulting upward boundary layer from the stagnation point to the corner produces smaller near-wall secondary flow motion and more relaxed merger with the main flow. All this contributes to enhanced drag reduction for the described groove structure.

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Feedback control of wall turbulence with wall deformation

Cited by 72 publications

References 31 publications

Effectiveness of active flow control for turbulent skin friction drag reduction

Effectiveness of active flow control for turbulent skin friction drag reduction

Electrokinetic Microactuator Arrays for Control of Vehicles

CFD modeling of turbulent boundary layer flow in passive drag-reducing applications

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