Wall Oscillation Induced Drag Reduction Zone in a Turbulent Boundary Layer

Skote, Martin; Mishra, Maneesh; Wu, Yanhua

doi:10.1007/s10494-018-9979-2

Cited by 18 publications

(20 citation statements)

References 45 publications

(126 reference statements)

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“…On the other hand, Ref. [9] repeated the DNS of [4] at Re θ = 1400 and obtained identical DR as in the experiments [23]. In addition, Ref.…”

Section: Downstream Variationsupporting

confidence: 54%

“…In addition, previous and new simulations with pure temporal forcing and pure spatial forcing are shown for comparison Figure 1a. The previous boundary layer results are taken from [4,5,9] (see Table 1). All of these cases were performed with the same amplitude (W + m = 12) as in the travelling wave simulation, except the case with T + = 67, which has an amplitude of W + m = 11.3.…”

Section: Compilation Of Old and New Datamentioning

confidence: 99%

“…Since then, large research efforts were devoted to internal flows, such as in a channel or pipe flow. The boundary layer flows only recently started to be investigated numerically ( [2][3][4][5][6][7][8][9]), while experiments were previously performed by a number of researchers. In fact, the first experimental evidence that confirmed Jung's DNS results was provided by [10], who applied the oscillation technique to the boundary layer flow.…”

Section: Introductionmentioning

confidence: 99%

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Drag Reduction of Turbulent Boundary Layers by Travelling and Non-Travelling Waves of Spanwise Wall Oscillations

Skote

2022

Fluids

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Turbulence control in the form of a streamwise travelling wave of transverse wall motion was studied numerically by employing direct numerical simulations (DNS). Both total and phase averaging were utilised to examine the statistical behaviour of the turbulence affected by the wall forcing, with a focus on the skin friction. Comparison with results from pure temporal and spatial wall forcing are conducted, and a compilation of data is used to explore analogies with drag-reduced channel flow.

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“…On the other hand, Ref. [9] repeated the DNS of [4] at Re θ = 1400 and obtained identical DR as in the experiments [23]. In addition, Ref.…”

Section: Downstream Variationsupporting

confidence: 54%

Section: Compilation Of Old and New Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Drag Reduction of Turbulent Boundary Layers by Travelling and Non-Travelling Waves of Spanwise Wall Oscillations

Skote

2022

Fluids

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“…Later, Baron & Quadrio (1995) estimated the control power input and demonstrated that net power saving is possible if the control parameters are appropriately chosen. Inspired by these pioneering works, numerous studies have been performed for various types of flows, such as channel flow (Choi, Xu & Sung 2002; Quadrio & Ricco 2004; Ricco & Quadrio 2008; Touber & Leschziner 2012; Agostini, Touber & Leschziner 2014), pipe flow (Orlandi & Fatica 1997; Quadrio & Sibilla 2000) and boundary layer flow (Laadhari, Skandaji & Morel 1994; Lardeau & Leschziner 2013; Hack & Zaki 2014; Skote, Mishra & Wu 2015, 2019).…”

Section: Introductionmentioning

confidence: 99%

Supersonic turbulent boundary layer drag control using spanwise wall oscillation

Yao

Hussain

2019

J. Fluid Mech.

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Spanwise wall oscillation has been extensively studied to explore possible drag control methods, mechanisms and efficacy – particularly for incompressible flows. We performed direct numerical simulation for fully developed turbulent channel flow to establish how effective spanwise wall oscillation is when the flow is compressible and also to document its drag reduction (${\mathcal{D}}{\mathcal{R}}$) trend with Mach number. Drag reduction ${\mathcal{D}}{\mathcal{R}}$ is first investigated for three different bulk Mach numbers $M_{b}=0.3$, $0.8$ and $1.5$ at a fixed bulk Reynolds number $Re_{b}=3000$. At a given velocity amplitude $A^{+}$ ($=12$), ${\mathcal{D}}{\mathcal{R}}$ at $M_{b}=0.3$ agrees with the strictly incompressible case; at $M_{b}=0.8$, ${\mathcal{D}}{\mathcal{R}}$ exhibits a similar trend to that at $M_{b}=0.3$: ${\mathcal{D}}{\mathcal{R}}$ increases with the oscillation period $T^{+}$ to a maximum and then decreases gradually. However, at $M_{b}=1.5$, ${\mathcal{D}}{\mathcal{R}}$ monotonically increases with $T^{+}$. In addition, the maximum ${\mathcal{D}}{\mathcal{R}}$ is found to increase with $M_{b}$. For $M_{b}=1.5$, similar to the incompressible case, ${\mathcal{D}}{\mathcal{R}}$ increases with $A^{+}$, but the rate of increase decreases at larger $A^{+}$. Unlike the flow behaviour when incompressible, the flow surprisingly relaminarizes when it is supersonic (at $A^{+}=18$ and $T^{+}=300$) – this enigmatic behaviour requires further detailed studies for different domain sizes, $Re_{b}$ and $M_{b}$. The Reynolds number effect on ${\mathcal{D}}{\mathcal{R}}$ is also investigated. Although ${\mathcal{D}}{\mathcal{R}}$ generally decreases with $Re_{b}$, it is less affected at small $T^{+}$, but drops rapidly at large $T^{+}$. We introduce a simple scaling for the oscillation period as $T^{\ast }=T_{C}^{+}l_{I}^{+}/l_{C}^{+}$, with $l_{I}^{+}$ and $l_{C}^{+}$ denoting the mean streak spacing for incompressible and compressible cases, respectively. At the same semi-local Reynolds number $Re_{\unicode[STIX]{x1D70F}c}^{\ast }\equiv Re_{\unicode[STIX]{x1D70F}}\sqrt{\overline{\unicode[STIX]{x1D70C}}_{c}/\overline{\unicode[STIX]{x1D70C}}_{w}}/(\overline{\unicode[STIX]{x1D707}}_{c}/\overline{\unicode[STIX]{x1D707}}_{w})$ (subscripts $c$ and $w$ denote quantities at the channel centre and wall, respectively), ${\mathcal{D}}{\mathcal{R}}$ as a function of $T^{\ast }$ exhibits good agreement between the supersonic and strictly incompressible cases, with the optimal oscillation period becoming $M_{b}$-invariant as $T_{opt}^{\ast }\approx 100$.

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“…One of the most promising candidates for significantly reducing drag is spanwise oscillation of surface elements synchronized to produce a travelling wave in the direction opposite to that of the fluid stream, as shown in Fig. 1a [7][8][9][10][11][12][13][14][15][16][17][18] . The sinusoidal oscillation is prescribed by w s ðx; tÞ ¼ A sinðκ x x À ωtÞ; ð1Þ in which w s is the instantaneous (spanwise) wall velocity, A is its amplitude, ω is the angular frequency of spanwise oscillations, and κ x = 2π/λ is the streamwise wavenumber of the travelling wave.…”

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confidence: 99%

An energy-efficient pathway to turbulent drag reduction

et al. 2021

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Simulations and experiments at low Reynolds numbers have suggested that skin-friction drag generated by turbulent fluid flow over a surface can be decreased by oscillatory motion in the surface, with the amount of drag reduction predicted to decline with increasing Reynolds number. Here, we report direct measurements of substantial drag reduction achieved by using spanwise surface oscillations at high friction Reynolds numbers ($${{{\mathrm{Re}}}_{\tau }}$$ Re τ ) up to 12,800. The drag reduction occurs via two distinct physical pathways. The first pathway, as studied previously, involves actuating the surface at frequencies comparable to those of the small-scale eddies that dominate turbulence near the surface. We show that this strategy leads to drag reduction levels up to 25% at $${{{{{{{{\mathrm{Re}}}}}}}}}_{\tau }$$ Re τ = 6,000, but with a power cost that exceeds any drag-reduction savings. The second pathway is new, and it involves actuation at frequencies comparable to those of the large-scale eddies farther from the surface. This alternate pathway produces drag reduction of 13% at $${{{{{{{{\mathrm{Re}}}}}}}}}_{\tau }$$ Re τ = 12,800. It requires significantly less power and the drag reduction grows with Reynolds number, thereby opening up potential new avenues for reducing fuel consumption by transport vehicles and increasing power generation by wind turbines.

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Wall Oscillation Induced Drag Reduction Zone in a Turbulent Boundary Layer

Cited by 18 publications

References 45 publications

Drag Reduction of Turbulent Boundary Layers by Travelling and Non-Travelling Waves of Spanwise Wall Oscillations

Drag Reduction of Turbulent Boundary Layers by Travelling and Non-Travelling Waves of Spanwise Wall Oscillations

Supersonic turbulent boundary layer drag control using spanwise wall oscillation

An energy-efficient pathway to turbulent drag reduction

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