Wavy Walls, a Passive Way to Control the Transition to Turbulence. Detailed Simulation and Physical Explanation

Inducing spanwise motions in the vicinity of solid boundaries alters the energy, mass and/or momentum transfer. Under some conditions, these motions are such that drag is reduced and/or transition to turbulence is delayed. There are several possibilities to induce those spanwise motions, be it throu...

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Bibliographic Details
Published inEnergies (Basel) Vol. 14; no. 13; p. 3937
Main Authors Mateo-Gabín, Andrés, Chávez, Miguel, Garicano-Mena, Jesús, Valero, Eusebio
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.07.2021
Subjects
Boundary conditions
Computational fluid dynamics
Configurations
Decomposition
Direct numerical simulation
Drag reduction
Flow control
Fluid flow
Friction
Laminar flow
Mathematical models
Momentum transfer
Passive control
Reynolds number
Simulation
transition
Turbulence
Velocity
Velocity distribution
wavy wall
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Summary:Inducing spanwise motions in the vicinity of solid boundaries alters the energy, mass and/or momentum transfer. Under some conditions, these motions are such that drag is reduced and/or transition to turbulence is delayed. There are several possibilities to induce those spanwise motions, be it through active imposition a predefined velocity distribution at the walls or by careful design of the wall shape, which corresponds to passive control.In this contribution, we investigate the effect that wavy walls might have on delaying transition to turbulence. Direct Numerical Simulation of both planar and wavy-walled channel flows at laminar and turbulent regimes are conducted. A pseudo laminar regime that remains stable until a Reynolds number 20% higher that the critical is found for the wavy-walled simulations. Dynamic Mode Decomposition applied to the simulation data reveals that in these configurations, modes with wavelength and frequency compatible with the surface undulation pattern appear. We explain and visualize the appearance of these modes. At higher Reynolds numbers we show that these modes remain present but are not dominant anymore. This work is an initial demonstration that flow control strategies that trigger underlying stable modes can keep or conduct the flow to new configurations more stable than the original one.
ISSN:1996-1073
1996-1073
DOI:10.3390/en14133937