Direct numerical simulation of a turbulent boundary layer over an oscillating wall

Yudhistira, Indra; Skote, Martin

doi:10.1080/14685248.2010.538397

Cited by 47 publications

(77 citation statements)

References 27 publications

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“…Hence, our initial step consists in verifying whether the travelling waves consistently produce a vertical shift ∆B of the mean velocity profile. This is a known result (see for instance Baron & Quadrio 1996;Ricco & Wu 2004;Yudhistira & Skote 2011;Ricco et al 2012;Touber & Leschziner 2012;Skote 2014;Hurst et al 2014) that is systematically checked in figure 10 (a)-(d). The mean velocity profiles are obtained at both Re from the largebox simulations described in §2.2 (discretization details have been reported in the lower half of table 1).…”

Section: Characterizing R Via the Vertical Shift ∆B Of The Mean Velocmentioning

confidence: 77%

Reynolds-number dependence of turbulent skin-friction drag reduction induced by spanwise forcing

2016

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This paper examines how increasing the value of the Reynolds number Re affects the ability of spanwise-forcing techniques to yield turbulent skin-friction drag reduction. The considered forcing is based on the streamwise-travelling waves of spanwise wall velocity (Quadrio et al. J. Fluid Mech., vol. 627, 2009, pp. 161-178). The study builds upon an extensive drag-reduction database created with Direct Numerical Simulation of a turbulent channel flow for two, 5-fold separated values of Re, namely Re τ = 200 and Re τ = 1000. The sheer size of the database, which for the first time systematically addresses the amplitude of the forcing, allows a comprehensive view of the drag-reducing characteristics of the travelling waves, and enables a detailed description of the changes occurring when Re increases. The effect of using a viscous scaling based on the friction velocity of either the non-controlled flow or the drag-reduced flow is described. In analogy with other wall-based drag reduction techniques, like for example riblets, the performance of the travelling waves is well described by a vertical shift of the logarithmic portion of the mean streamwise velocity profile. Except when Re is very low, this shift remains constant with Re, at odds with the percentage reduction of the friction coefficient, which is known to present a mild, logarithmic decline. Our new data agree with the available literature, which is however mostly based on low-Re information and hence predicts a quick drop of maximum drag reduction with Re. The present study supports a more optimistic scenario, where for an airplane at flight Reynolds numbers a drag reduction of nearly 30% would still be possible thanks to the travelling waves.

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Section: Characterizing R Via the Vertical Shift ∆B Of The Mean Velocmentioning

confidence: 77%

Reynolds-number dependence of turbulent skin-friction drag reduction induced by spanwise forcing

2016

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“…As already mentioned, no Reynolds number effect was observed in the boundary-layer experiment of Ricco & Wu (2004). Numerical simulations of the turbulent boundary layer with wall oscillation have been performed in a few studies (Yudhistira & Skote 2011;Skote 2012;Lardeau & Leschziner 2013). A drag reduction of DR = 29.4% was obtained at Re θ = 500 (or Re τ = 260) for A + = 12 and T + = 132 (Skote 2012).…”

Section: Reynolds Number Effectmentioning

confidence: 87%

“…The maximum drag reduction is found at 48%, also by a forward travelling wave, and the maximum net power saving is found as 18% (ω ≈ 0.15, κ x ≈ 1), with an even larger saving of 26% for a lower value of A + = 6. Since the first direct numerical simulation (DNS) study of wall oscillation for flow control by Jung et al (1992), a number of DNS studies have been performed for the channel flow (Baron & Quadrio 1996;Choi et al 2002;Ricco & Quadrio 2008;Quadrio et al 2009;Viotti et al 2009;Ricco et al 2012;Touber & Leschziner 2012), pipe flow (Orlandi & Fatica 1997;Quadrio & Sibilla 2000) and boundary-layer flow (Yudhistira & Skote 2011;Skote 2012Skote , 2013Lardeau & Leschziner 2013). Although the drag reduction of wall oscillation has been found to decrease as the Reynolds number increases, the majority of previous studies have been confined to lower Reynolds numbers, and also the Reynolds number range investigated has not been wide enough to give a clear indication of the Reynolds number effect on the drag reduction.…”

Section: Introductionmentioning

confidence: 99%

The effect of Reynolds number on turbulent drag reduction by streamwise travelling waves

2014

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A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription For more information, please contact the WRAP Team at: wrap@warwick.ac.ukUnder consideration for publication in J. Fluid Mech. 1The effect of Reynolds number on turbulent drag reduction by streamwise travelling waves This paper exploits the turbulent flow control method using streamwise travelling waves ) to study the effect of Reynolds number on turbulent skin-friction drag reduction. Direct numerical simulations of a turbulent channel flow subjected to the streamwise travelling waves of spanwise wall velocity have been performed at Reynolds numbers ranging from Re τ = 200 to 1600. To the best of the authors' knowledge, this is the highest Reynolds number attempted with DNS for this type of flow control. The present DNS results confirm that the effectiveness of drag reduction deteriorates, and the maximum drag reduction achieved by travelling waves decreases significantly as the Reynolds number increases. The intensity of both the drag reduction and drag increase is reduced with the Reynolds number. Another important finding is that the value of the optimal control parameters changes, even in wall units, when the Reynolds number is increased. This trend is observed for the wall oscillation, stationary wave, and streamwise travelling wave cases. This implies that, when the control parameters used are close to optimal values found at a lower Reynolds number, the drag reduction deteriorates rapidly with increased Reynolds number. In this study, the effect of Reynolds number for the travelling wave is quantified using a scaling in the form Re −α τ . No universal constant is found for the scaling parameter α. Instead, the scaling parameter α has a wide range of values depending on the flow control conditions. Further Reynolds number scaling issues are discussed. Turbulent statistics are analysed to explain a weaker drag reduction observed at high Reynolds numbers. The changes in the Stokes layer and also the mean and r.m.s. velocity with the Reynolds number are also reported. The Reynolds shear stress analysis suggests an interesting possibility of a finite drag reduction at very high Reynolds numbers.

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“…Similar transitional function was also adopted by Yudhistira and Skote [24] as well as Skote [14]. The Mach number of the incoming free stream flow is M = 2.9 and the Reynolds number is set as Re = 16,265.8.…”

Section: Computational Setupmentioning

confidence: 99%

“…At the upper and the outlet planes, the generalized non-reflecting boundary conditions [27,28] are used. Similar transitional function was also adopted by Yudhistira and Skote [24] as well as Skote [14]. The Mach number of the incoming free stream flow is M = 2.9 and the Reynolds number is set as Re = 16,265.8.…”

Section: Computational Setupmentioning

confidence: 99%

Direct Numerical Simulation of Supersonic Turbulent Boundary Layer with Spanwise Wall Oscillation

Ribault

et al. 2016

Energies

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Direct numerical simulations (DNS) of Mach = 2.9 supersonic turbulent boundary layers with spanwise wall oscillation (SWO) are conducted to investigate the turbulent heat transport mechanism and its relation with the turbulent momentum transport. The turbulent coherent structures are suppressed by SWO and the drag is reduced. Although the velocity and temperature statistics are disturbed by SWO differently, the turbulence transports of momentum and heat are simultaneously suppressed. The Reynolds analogy and the strong Reynolds analogy are also preserved in all the controlled flows, proving the consistent mechanisms of momentum transport and heat transport in the turbulent boundary layer with SWO. Despite the extra dissipation and heat induced by SWO, a net wall heat flux reduction can be achieved with the proper selected SWO parameters. The consistent mechanism of momentum and heat transports supports the application of turbulent drag reduction technologies to wall heat flux controls in high-speed vehicles.

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Direct numerical simulation of a turbulent boundary layer over an oscillating wall

Cited by 47 publications

References 27 publications

Reynolds-number dependence of turbulent skin-friction drag reduction induced by spanwise forcing

Reynolds-number dependence of turbulent skin-friction drag reduction induced by spanwise forcing

The effect of Reynolds number on turbulent drag reduction by streamwise travelling waves

Direct Numerical Simulation of Supersonic Turbulent Boundary Layer with Spanwise Wall Oscillation

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