Resolvent modelling of near-wall coherent structures in turbulent channel flow

Abreu, Leandra I.; Cavalieri, André V. G.; Schlatter, Philipp; Vinuesa, Ricardo; Henningson, Dan S.

doi:10.1016/j.ijheatfluidflow.2020.108662

Cited by 34 publications

(50 citation statements)

References 29 publications

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“…The lift-up mechanism (Ellingsen & Palm 1975) and the associated coherent structures, streaks, have long been understood as an important mechanism in wall-bounded flows (see review by Brandt (2014) and references therein). Parallel to the history of mechanism identification in jet flows, the lift-up mechanism and its interplay with the Tollmien-Schlichting and Orr mechanisms has been systematically described, first through observations (Kline et al 1967;Kim, Kline & Reynolds 1971;Klebanoff 1971), then local analyses (Moffatt 1965;Ellingsen & Palm 1975;Landahl 1980), followed by transient growth (Butler & Farrell 1992;Farrell & Ioannou 1993) and most recently resolvent analysis (Hwang & Cossu 2010;Marant & Cossu 2018;Abreu et al 2019). The salient properties of the lift-up mechanism include streamwise vortices (rolls with streamwise vorticity) that lift up low-speed fluid from the wall (and push high-speed fluid toward the wall) until viscous dissipation becomes important.…”

Section: Introductionmentioning

confidence: 99%

Lift-up, Kelvin–Helmholtz and Orr mechanisms in turbulent jets

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Lift-up, Kelvin–Helmholtz and Orr mechanisms in turbulent jets

et al. 2020

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“…(2013) and Abreu et al. (2020 a , b ), to cite a few examples. Usually such linearised models lead to a definition of a set of modes that together describe coherent turbulent structures.…”

Section: Introductionmentioning

confidence: 99%

Spanwise-coherent hydrodynamic waves around flat plates and airfoils

et al. 2021

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We investigate spanwise-coherent structures in the turbulent flow around airfoils, motivated by their connection with trailing-edge noise. We analyse well-resolved large-eddy simulations (LES) of the flow around NACA 0012 and NACA 4412 airfoils, both at a Reynolds number of 400 000 based on the chord length. Spectral proper orthogonal decomposition performed on the data reveals that the most energetic coherent structures are hydrodynamic waves, extending over the turbulent boundary layers around the airfoils with significant amplitudes near the trailing edge. Resolvent analysis was used to model such structures, using the mean field as a base flow. We then focus on evaluating the dependence of such structures on the domain size, to ensure that they are not an artefact of periodic boundary conditions in small computational boxes. To this end, we performed incompressible LES of a zero-pressure-gradient turbulent boundary layer, for three different spanwise sizes, with the momentum-thickness Reynolds number matching those near the airfoils trailing edge. The same coherent hydrodynamic waves were observed for the three domains. Such waves are accurately modelled as the most amplified flow response from resolvent analysis. The signature of such wide structures is seen in non-premultiplied spanwise wavenumber spectra, which collapse for the three computational domains. These results suggest that the spanwise-elongated structures are not domain-size dependent for the studied simulations, indicating thus the presence of very wide structures in wall-bounded turbulent flows.

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“…Spectral proper orthogonal decomposition (SPOD) [160] is an extension of POD recently introduced for analysis and pattern identification in turbulent flows [162,[177][178][179]. This method calculates the POD modes in the frequency domain, combining the good properties of POD with the information contained in a temporal modal expansion as in dynamic mode decomposition (described below).…”

Section: Appendix A2 Spectral Proper Orthogonal Decompositionmentioning

confidence: 99%

On the Experimental, Numerical and Data-Driven Methods to Study Urban Flows

2021

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Understanding the flow in urban environments is an increasingly relevant problem due to its significant impact on air quality and thermal effects in cities worldwide. In this review we provide an overview of efforts based on experiments and simulations to gain insight into this complex physical phenomenon. We highlight the relevance of coherent structures in urban flows, which are responsible for the pollutant-dispersion and thermal fields in the city. We also suggest a more widespread use of data-driven methods to characterize flow structures as a way to further understand the dynamics of urban flows, with the aim of tackling the important sustainability challenges associated with them. Artificial intelligence and urban flows should be combined into a new research line, where classical data-driven tools and machine-learning algorithms can shed light on the physical mechanisms associated with urban pollution.

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Resolvent modelling of near-wall coherent structures in turbulent channel flow

Cited by 34 publications

References 29 publications

Lift-up, Kelvin–Helmholtz and Orr mechanisms in turbulent jets

Lift-up, Kelvin–Helmholtz and Orr mechanisms in turbulent jets

Spanwise-coherent hydrodynamic waves around flat plates and airfoils

On the Experimental, Numerical and Data-Driven Methods to Study Urban Flows

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