Model-based design of riblets for turbulent drag reduction

Both experiments and direct numerical simulations have been used to demonstrate that riblets can reduce turbulent drag by as much as $10\,\%$, but their systematic design remains an open challenge. In this paper we develop a model-based framework to quantify the effect of streamwise-aligned spanwise...

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Bibliographic Details
Published in:Journal of fluid mechanics Vol. 906
Main Authors: Ran, Wei, Zare, Armin, Jovanović, Mihailo R.
Format: Journal Article
Language:English
Published: Cambridge, UK Cambridge University Press 10.01.2021
Subjects:
Channel flow
Computational fluid dynamics
Direct numerical simulation
Drag
Drag reduction
Experiments
Flow structures
Fluid mechanics
Friction
Friction drag
JFM Papers
Kinetic energy
Mathematical models
Navier-Stokes equations
Optimization
Performance degradation
Riblets
Simulation
Skin
Skin friction
Trends
Turbulence
Turbulence models
Turbulent flow
Velocity
Viscosity
Vortices
turbulence control
drag reduction
turbulence modelling
ISSN:0022-1120, 1469-7645
Online Access:Get full text
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Summary:Both experiments and direct numerical simulations have been used to demonstrate that riblets can reduce turbulent drag by as much as $10\,\%$, but their systematic design remains an open challenge. In this paper we develop a model-based framework to quantify the effect of streamwise-aligned spanwise-periodic riblets on kinetic energy and skin-friction drag in turbulent channel flow. We model the effect of riblets as a volume penalization in the Navier–Stokes equations and use the statistical response of the eddy-viscosity-enhanced linearized equations to quantify the effect of background turbulence on the mean velocity and skin-friction drag. For triangular riblets, our simulation-free approach reliably predicts drag-reducing trends as well as mechanisms that lead to performance deterioration for large riblets. We investigate the effect of height and spacing on drag reduction and demonstrate a correlation between energy suppression and drag reduction for appropriately sized riblets. We also analyse the effect of riblets on drag-reduction mechanisms and turbulent flow structures including very large-scale motions. Our results demonstrate the utility of our approach in capturing the effect of riblets on turbulent flows using models that are tractable for analysis and optimization.
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ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2020.722