DNS study of turbulence modification with streamwise-uniform sinusoidal wall-oscillation

Mito, Yoichi; Kasagi, Nobuhide

doi:10.1016/s0142-727x(98)10025-5

Cited by 22 publications

(10 citation statements)

References 14 publications

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“…They showed that a drag reduction ratio up to 9% could be obtained, and that two key features for drag reduction were the damping of the wall-normal vorticity fluctuations above the entire surface and the decrease of turbulence production. On the other hand, DNS of Mito and Kasagi [53] showed that no drag reduction could be achieved by a streamwiseuniform sinusoidal wall-oscillation, i.e. a spanwise-standing wave with wall deformation.…”

Section: Introductionmentioning

confidence: 99%

Drag reduction in turbulent boundary layers by spanwise traveling waves with wall deformation

Tamano

Itoh

2012

Journal of Turbulence

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The drag-reducing effect of a spanwise-traveling wave with wall deformation on a zeropressure-gradient turbulent boundary layer over a flexible sheet was investigated. The test plate placed in the wind tunnel consisted of a flexible sheet section, where the traveling wave motion was generated by a vibration device with a crank via upstream and downstream smooth rigid wall sections. Streamwise and wall-normal velocity components were measured by single and cross hot-wire anemometers. Amplitude and frequency of the spanwise-traveling-wave motion were measured using two laser displacement sensors. The drag reduction ratio was estimated from the friction coefficients through the growth rate of the momentum thickness of the turbulent boundary layer over the flexible sheet section. A maximum drag reduction ratio DR of up to 13% was obtained. The relations between sheet displacement and streamwise and wall-normal velocity fluctuations were compared at a large DR (DR = 8%) and at a very small DR (DR = 2%), which was almost the same as the no drag reduction case, taking into account the experimental uncertainty. For the larger drag reduction, a slow-velocity fluctuation with large amplitude appeared further away from the flexible sheet. Quadrant analysis of streamwise and wall-normal velocity fluctuations revealed that the drag reduction was attributed to a reduction in the sweep event and an increase in the negative contribution of the inward-interaction event to the Reynolds shear stress due to the sheet displacement fluctuation.

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Section: Introductionmentioning

confidence: 99%

Drag reduction in turbulent boundary layers by spanwise traveling waves with wall deformation

Tamano

Itoh

2012

Journal of Turbulence

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“…Taneda and Tomonari [26] investigated the flow over a flexible plate with a streamwise traveling-wave motion with a wall deformation, and observed that such a motion had a strong effect on laminarizing the turbulent boundary-layer flow. In a typical DNS of a wall-bounded turbulent flow with a wall deformation, Mito and Kasagi [27] performed a DNS of a turbulent channel flow with a streamwiseuniform sinusoidal wall-oscillation (i.e., with a spanwise standing-wave motion), and showed that no drag reduction could be achieved by that motion. Kang and Choi [28] performed a DNS of a turbulent channel flow with an active and local wall motion, and found that most of the drag reduction up to 17% was due to the wall-normal velocity induced by the wall motion rather than to the wall displacement itself.…”

Section: Introductionmentioning

confidence: 99%

Drag reduction in a turbulent boundary layer on a flexible sheet undergoing a spanwise traveling wave motion

Itoh

Tamano

Yokota

et al. 2006

Journal of Turbulence

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“…raising the actuator underneath a low-speed streak increases skin-friction drag by allowing the adjacent high-speed region to expand, and vice versa. Mito and Kasagi (1998) performed DNS of turbulent channel flows with a simple oscillatory mode of wall deformation, uniform in the streamwise direction and sinusoidal in the spanwise direction and in time, and then found that the oscillatory wall motions are effective in altering the skin friction and statistical quantities, but hardly reduce drag.…”

Section: Methodsmentioning

confidence: 99%

Approximate coordinate transformations for simulation of turbulent flows with wall deformation

Kang

2002

KSME International Journal

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In the present paper, approximate coordinate transformations for simulation of turbulent flows with wall deformation, significantly reducing computational cost with little degradation in numerical accuracy, are presented. The Navier-Stokes equations are coordinate-transformed with an approximation of Taylor-series truncation. The performance is evaluated by performing numerical simulations of a channel flow at Re-> 140 with active wall motions of I 7/;' I~5. The approximate transformations provide flow structures as well as turbulence statistics in good agreement with those from a complete transformation [Phys. Fluids 12,3301 (2000) ] and allow 25-30% savings in the CPU time as compared to the complete one.

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DNS study of turbulence modification with streamwise-uniform sinusoidal wall-oscillation

Cited by 22 publications

References 14 publications

Drag reduction in turbulent boundary layers by spanwise traveling waves with wall deformation

Drag reduction in turbulent boundary layers by spanwise traveling waves with wall deformation

Drag reduction in a turbulent boundary layer on a flexible sheet undergoing a spanwise traveling wave motion

Approximate coordinate transformations for simulation of turbulent flows with wall deformation

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