Parametric investigation of friction drag reduction in turbulent flow over a flexible wall undergoing spanwise transversal traveling waves

Li, Wenfeng; Roggenkamp, Dorothee; Hecken, Tobias; Jessen, Wilhelm; Klaas, Michael; Schröder, Wolfgang

doi:10.1007/s00348-018-2559-3

Cited by 25 publications

(23 citation statements)

References 41 publications

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“…That is, at a given period the strength of the actuation is determined by the amplitude. This is confirmed by the experimental findings of Li et al [30]. They obtain in a lower amplitude range a monotonic increase of the skin-friction reduction for increasing amplitude.…”

Section: Wall-shear Stress Reductionssupporting

confidence: 86%

“…Fig.4(a)). The longest wavelength considered in this study (λ + = 3000) is comparable to that used in the experimental setups by Tamano and Itoh [47] and Li et al [30]. Although their lowest investigated period is T + ≈ 110 and thus considerably higher than the optimum found in this study, their results corroborate the tendency of higher wall-shear stress reduction at lower periods in the regime 110 ≤ T + ≤ 302.5.…”

Section: Wall-shear Stress Reductionssupporting

confidence: 84%

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Drag Reduction and Energy Saving by Spanwise Traveling Transversal Surface Waves for Flat Plate Flow

Albers

Meysonnat

Fernex

et al. 2020

Flow Turbulence Combust

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Wall-resolved large-eddy simulations are performed to study the impact of spanwise traveling transversal surface waves in zero-pressure gradient turbulent boundary layer flow. Eighty variations of wavelength, period, and amplitude of the space-and time-dependent sinusoidal wall motion are considered for a boundary layer at a momentum thickness based Reynolds number of Re θ = 1000. The results show a strong decrease of friction drag of up to 26 % and considerable net power saving of up to 10 %. However, the highest net power saving does not occur at the maximum drag reduction. The drag reduction is modeled as a function of the actuation parameters by support vector regression using the LES data. A substantial attenuation of the near-wall turbulence intensity and especially a weakening of the near-wall velocity streaks are observed. Similarities between the current actuation technique and the method of a spanwise oscillating wall without any normal surface deflection are reported. In particular, the generation of a directional spanwise oscillating Stokes layer is found to be related to skin-friction reduction.

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Section: Wall-shear Stress Reductionssupporting

confidence: 86%

Section: Wall-shear Stress Reductionssupporting

confidence: 84%

Drag Reduction and Energy Saving by Spanwise Traveling Transversal Surface Waves for Flat Plate Flow

Albers

Meysonnat

Fernex

et al. 2020

Flow Turbulence Combust

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“…This was consistently observed at different locations over the traveling wave surface and the change in boundary layer was seen even when accounting for experimental uncertainty. This thickening of the viscous sublayer is the same effect that was seen in other studies investigating the effect of traveling waves [4,5,26,30]. In addition, this effect was also seen when investigating spanwise in-plane wall motion [24] and also compliant wall effects [99].…”

Section: Discussionsupporting

confidence: 76%

“…Multiple studies have suggested that the optimal excitation period for affecting the boundary layer and reducing skin friction drag is T + ≈ 100. This was shown both for spanwise traveling waves [5,8,30] and also for spanwise in-plane wall motion [24]. This timescale is roughly the same as that of the bursting events [85], which are a major source of turbulence production and responsible for an increase in the skin friction [23].…”

Section: Traveling Wave Generationmentioning

confidence: 65%

“…The use of spanwise (perpendicular to flow) traveling, surface waves as an active drag reduction mechanism has been researched both computationally and experimentally [3][4][5][6][7][8][26][27][28][29][30][31][32]. These studies have investigated the underlying drag reduction mechanism, the dependence on traveling wave parameters, and also varying flow conditions.…”

Section: Chapter 1 Introductionmentioning

confidence: 99%

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Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Musgrave

Tarazaga

2019

AIAA Scitech 2019 Forum

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Skin friction drag plays a significant role in determining the fuel efficiency of a vehicle. Reducing the skin friction thus has implications in a number of applications such as aircraft, ships, and automobiles. In recent years, a large amount of studies have researched various active drag reduction methods. One particular method involves active wall motion with the use of spanwise traveling waves. These out-of-plane traveling waves interact with the vortices in the turbulent boundary layer and weaken the bursting events that are responsible for increased skin friction drag. Computational and experimental studies have shown that these spanwise traveling waves are able to reduce the skin friction by upwards of 13% in turbulent flow. However, previous studies generated traveling waves using bulky actuation setups requiring arrays of discrete actuators that limited the achievable bandwidth and traveling wave patterns. In order for traveling waves to be a practical drag reduction method, a more implementable wave generation method is necessary. A promising traveling wave generation method is known as two-mode excitation. This technique takes advantages of a surface's inherent structural properties to generate steady-state traveling waves in an open-loop fashion. In addition, the waves can be excited at most frequencies and using a small number of low-profile piezoelectric actuators. Previous research into two-mode excitation has primarily focused on one-dimensional beams. Traveling waves have been generated on a two-dimensional surface, but this was done from a fundamental standpoint with the resultant waves propagating in arbitrary directions. Before the two-mode excitation method can be applied for drag reduction, traveling waves must be generated on two-dimensional surfaces with tailorable propagation patterns. The goal of this research is the development and testing of an implementable traveling wave generation method that alters the turbulent boundary layer with the aim of reducing skin friction drag. The first objective is to further develop the two-mode excitation method in order to tailor the traveling waves generated on a two-dimensional plate. Then, these tailored traveling waves are experimentally tested to determine their effect on the turbulent boundary layer. By directly investigating the boundary layer, a more fundamental approach is taken than only focusing on the skin friction drag. Finally, the overall effect of the traveling waves on the boundary layer are compared with standing waves. vii None of this would have been possible without the support of my family. My parents, Robert and Jacqueline, you raised me to be the person I am today. You have always been there with support and encouragement, and I am eternally grateful. I want to thank my brothers, Brian and Robert, and their wives, Katie and Lindsay. You are always there to chat and you provided many late nights of fun. Finally, I want to thank Alexis Gushiken and the endless support she has given. You always know when to motivate, encourage, o...

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Parameter Study of Turbulent Drag Reduction by Spanwise Traveling Transversal Surface Waves

Albers

Meysonnat

Fernex

et al. 2019

Proc Appl Math and Mech

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Parametric investigation of friction drag reduction in turbulent flow over a flexible wall undergoing spanwise transversal traveling waves

Cited by 25 publications

References 41 publications

Drag Reduction and Energy Saving by Spanwise Traveling Transversal Surface Waves for Flat Plate Flow

Drag Reduction and Energy Saving by Spanwise Traveling Transversal Surface Waves for Flat Plate Flow

Turbulent Boundary Layer over a Piezoelectrically Excited Traveling Wave Surface

Parameter Study of Turbulent Drag Reduction by Spanwise Traveling Transversal Surface Waves

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