Influence of Wave-Like Riblets on Turbulent Friction Drag

Grüneberger, René; Krämer, Felix; Wassen, Erik; Hage, W.; Meyer, Robert K.; Thiele, Frank

doi:10.1007/978-3-642-28302-4_19

Cited by 13 publications

(16 citation statements)

References 16 publications

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“…The simulation results suggest that the blade riblet geometry is more susceptible to yaw than any of the other geometries. This is likely not a low-Reynolds-number effect, as the simulations at Re b = 5750 by Grüneberger et al [36] reproduced well the experimental data (see the figure). Instead, it might be ascribed to the sharper riblet tips (and the associated pressure drag increase) and the broader riblet valleys (and the associated increase of sloshing) [38].…”

Section: Parallel Riblets In Yawsupporting

confidence: 66%

“…With a simplified riblet geometry, a maximum DR of almost 10% has been obtained [5]. In the search for even higher values of DR, many variations on the standard riblet geometries have been investigated [19], such as hierarchical or compound riblets [91], riblets on a spanwise traveling surface wave [47], oscillating riblets [88,37,83], riblets in a wave-like pattern (either in phase [36] or out of phase [69]) and riblets combined with drag-reducing polymers [12]. The rationale behind these alternatives is to further reduce drag by somehow incorporating other drag-reducing methods, such as oscillating walls or polymer addition.…”

Section: Introductionmentioning

confidence: 99%

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Drag reduction by herringbone riblet texture in direct numerical simulations of turbulent channel flow

Benschop

Breugem

2017

Journal of Turbulence

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A bird-feather-inspired herringbone riblet texture was investigated for turbulent drag reduction. The texture consists of blade riblets in a converging/diverging or herringbone pattern with spanwise wavelength f . The aim is to quantify the drag change for this texture as compared to a smooth wall and to study the underlying mechanisms. To that purpose, direct numerical simulations of turbulent flow in a channel with height L z were performed. The FukagataIwamoto-Kasagi identity for drag decomposition was extended to textured walls and was used to study the drag change mechanisms. For f /L z ࣡ O(10), the herringbone texture behaves similarly to a conventional parallel-riblet texture in yaw: the suppression of turbulent advective transport results in a slight drag reduction of 2%. For, the drag increases strongly with a maximum of 73%. This is attributed to enhanced mean and turbulent advection, which results from the strong secondary flow that forms over regions of riblet convergence/divergence. Hence, the employment of convergent/divergent riblets in the texture seems to be detrimental to turbulent drag reduction.

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Section: Parallel Riblets In Yawsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Drag reduction by herringbone riblet texture in direct numerical simulations of turbulent channel flow

Benschop

Breugem

2017

Journal of Turbulence

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“…The procedure for calculating ∆c f is described here in more detail. The local skin friction was basically calculated based on the turbulent boundary layer theory and the 1/7 power law applied to a flat smooth plate based on the Blasius formula [29] as presented by Equation (14). Note that this equation is equivalent to Equation (7) in case for a flat smooth plate:…”

Section: Evaluation Of Skin Friction Drag Reductionmentioning

confidence: 99%

“…Among those intensive past studies, three-dimensional sinusoidal riblets [9,[14][15][16][17] are found to be more effective compared to conventional straight-shaped riblets. Grüneberger et al [14] investigated the influence of wavelengths and amplitudes of sinusoidal riblets on the effectiveness of drag-reducing performance and concluded that certain combinations of a height/spacing ratio can improve drag reduction. However, the drag-reducing performance by the straight-shaped riblets could become comparable once the geometry of the riblet grooves aligned to the streamwise direction is optimized for the flowfield of interest.…”

Section: Introductionmentioning

confidence: 99%

“…To improve the drag-reducing performance further, multi-dimensional riblet shapes, such as two-dimensional 'blade riblets', which aligned a row of thin fences along the streamwise direction [12], and three-dimensional zigzag riblets [14], and sinusoidal riblets [9,[14][15][16][17], have emerged. Among those intensive past studies, three-dimensional sinusoidal riblets [9,[14][15][16][17] are found to be more effective compared to conventional straight-shaped riblets. Grüneberger et al [14] investigated the influence of wavelengths and amplitudes of sinusoidal riblets on the effectiveness of drag-reducing performance and concluded that certain combinations of a height/spacing ratio can improve drag reduction.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Skin Friction Drag Reduction in the Turbulent Boundary Layer Using Riblets

et al. 2019

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A unique approach to evaluate the reduction of skin friction drag by riblets was applied to boundary layer profiles measured in wind tunnel experiments. The proposed approach emphasized the turbulent scales based on hot-wire anemometry data obtained at a sampling frequency of 20 kHz in the turbulent boundary layer to evaluate the skin friction drag reduction. Three-dimensional riblet surfaces were fabricated using aviation paint and were applied to a flat-plate model surface. The turbulent statistics, such as the turbulent scales and intensities, in the boundary layer were identified based on the freestream velocity data obtained from the hot-wire anemometry. Those turbulent statistics obtained for the riblet surface were compared to those obtained for a smooth flat plate without riblets. Results indicated that the riblet surface increased the integral scales and decreased the turbulence intensity, which indicated that the turbulent structure became favorable for reducing skin friction drag. The proposed method showed that the current three-dimensional riblet surface reduced skin friction drag by about 2.8% at a chord length of 67% downstream of the model’s leading edge and at a freestream velocity of 41.7 m/s (Mach 0.12). This result is consistent with that obtained by the momentum integration method based on the pitot-rake measurement, which provided a reference dataset of the boundary layer profile.

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A review of turbulent skin-friction drag reduction by near-wall transverse forcing

Riccó

Skote

Leschziner

2021

Progress in Aerospace Sciences

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Influence of Wave-Like Riblets on Turbulent Friction Drag

Cited by 13 publications

References 16 publications

Drag reduction by herringbone riblet texture in direct numerical simulations of turbulent channel flow

Drag reduction by herringbone riblet texture in direct numerical simulations of turbulent channel flow

Evaluation of Skin Friction Drag Reduction in the Turbulent Boundary Layer Using Riblets

A review of turbulent skin-friction drag reduction by near-wall transverse forcing

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