Subgrid-scale energy transfer and near-wall turbulence structure

Piomelli, Ugo; Yu, Yunfang; Adrian, Ronald J.

doi:10.1063/1.868829

Cited by 120 publications

(131 citation statements)

References 19 publications

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“…1 and the qualitative nature of the pdf shown in Fig. 2 are consistent with those reported by Piomelli et al 26 in low-Re channel flow, lending support to the 2D approximation of sgs utilized herein.…”

Section: Filtering and Calculation Of Sgs Quantitiessupporting

confidence: 79%

“…For reference, the use of a threshold in this context is not without precedence as Piomelli et al 26 utilized a similar methodology for isolating the most significant energy transfer events in their low-Re DNS work. Further, the results presented are found to be qualitatively independent of the threshold, as thresholds ranging from a small fraction to four times the mean have been tested.…”

Section: ͑8͒mentioning

confidence: 99%

“…Based on conditionally averaged flow fields obtained using the variableinterval-spatial-averaging ͑VISA͒ technique, Hartel et al 25 concluded that energy transfer from the unresolved to the resolved scales in the near-wall region of wall turbulence is often accompanied by strong shear layers characteristic of intense bursting events. Piomelli et al 26 used low-Re DNS of turbulent channel flow to study the role of coherent structures in SGS energy transfer and concluded that near-wall turbulent structures are often accompanied by regions of forward and backward scatter occurring in close proximity to one another. Finally, the recent sonic anemometry experiments of Carper and Porte-Agel 27 in the atmospheric boundary layer provide detailed evidence linking local interscale energy transfer to three-dimensional ͑3D͒ coherent structures.…”

Section: Introductionmentioning

confidence: 99%

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The role of coherent structures in subgrid-scale energy transfer within the log layer of wall turbulence

Natrajan

Christensen

2006

Physics of Fluids

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The present effort documents the relationship between dominant subgrid-scale energy transfer events and coherent motions within the log layer of wall turbulence. Instantaneous velocity fields in the streamwise-wall-normal plane of a zero-pressure-gradient turbulent boundary layer acquired by particle-image velocimetry at Re ϵ u * ␦ / = 2350 are spatially filtered to generate an ensemble of resolved-scale velocity fields in the spirit of large-eddy simulation. The relationship between subgrid-scale dissipation and embedded coherent structures is then studied using instantaneous realizations and conditional averaging techniques. This analysis reveals that strong forward-and backward-scatter events occur spatially coincident to individual hairpin vortices and their larger-scale organization into vortex packets. In particular, large-scale regions of forward scatter are observed along the inclined interface of the packets, coincident with strong ejections induced by the individual vortices. The most intense forward-scatter events are found to occur when these ejections are opposed by sweep motions. Strong backward scatter of energy is observed at the trailing edge of the vortex packets and weaker backscatter is also noted locally around the individual heads of the hairpin structures. The collective observations presented herein demonstrate that hairpin vortices and their organization into larger-scale packets are important contributors to interscale energy transfer in the log layer of wall turbulence.

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Section: Filtering and Calculation Of Sgs Quantitiessupporting

confidence: 79%

Section: ͑8͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of coherent structures in subgrid-scale energy transfer within the log layer of wall turbulence

Natrajan

Christensen

2006

Physics of Fluids

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“…The results of this calculation were shown by Piomelli et al 12 to be in good agreement with the direct numerical simulations ͑DNS͒ of Kim et al 13 The accelerating channel case was computed using the same pseudo-spectral code; the flow was started from a steadystate field at Re ϭ150 ͑based on the initial friction velocity u ,o and viscosity o ); the Reynolds number was then suddenly increased, and a new equilibrium state was reached at Re ϭ225 at tu ,o /␦Ӎ1.2.…”

Section: Otherwise ͑13͒mentioning

confidence: 83%

On the effects of nonequilibrium on the subgrid-scale stresses

1997

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An a priori study of the subgrid-scale ͑SGS͒ stresses and dissipation in two nonequilibrium, wall-bounded flows is carried out. The velocity fields were computed by direct simulations of twoand three-dimensional boundary layers obtained, respectively, by a sudden change in the Reynolds number and by an impulsive motion in the spanwise direction of the lower wall of a plane channel in fully developed turbulent flow conditions. Several realizations of the transient period of the flow were examined. The SGS stresses react to the imposition of the secondary shear more rapidly than the large-scale ones, and return to equilibrium before the resolved stresses do. In general, the subgrid scales are less sensitive than the large ones to the near-wall and nonequilibrium effects. Scale-similar and dynamic models appear well-suited to reproduce the correlation between resolved Reynolds stress production and events with significant production of SGS energy. © 1997 American Institute of Physics.

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“…The description consists of elongated turbulent structures attached to the wall which are generated by the lift up and by the orienting effect of the mean flow on the spanwise vorticity (see, e.g., Perry, Henbest & Chong 1986;Marusic 2001;Nickels et al 2007). These turbulent structures while moving away from the wall, grow and remain attached to the wall thus leading to an increase of wall-normal scales corresponding to a sort of reverse cascade (see Piomelli, Yu & Adrian 1996). At a certain point, these structures detach and break down into smaller structures giving rise to a form of forward cascade.…”

Section: Introductionmentioning

confidence: 99%

Cascades and wall-normal fluxes in turbulent channel flows

et al. 2016

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The present work describes the multidimensional behaviour of scale-energy production, transfer and dissipation in wall-bounded turbulent flows. This approach allows us to understand the cascade mechanisms by which scale energy is transmitted scale-by-scale among different regions of the flow. Two driving mechanisms are identified. A strong scale-energy source in the buffer layer related to the near-wall cycle and an outer scale-energy source associated with an outer turbulent cycle in the overlap layer. These two sourcing mechanisms lead to a complex redistribution of scale energy where spatially evolving reverse and forward cascades coexist. From a hierarchy of spanwise scales in the near-wall region generated through a reverse cascade and local turbulent generation processes, scale energy is transferred towards the bulk, flowing through the attached scales of motion, while among the detached scales it converges towards small scales, still ascending towards the channel centre. The attached scales of wall-bounded turbulence are then recognized to sustain a spatial reverse cascade process towards the bulk flow. On the other hand, the detached scales are involved in a direct forward cascade process that links the scale-energy excess at large attached scales with dissipation at the smaller scales of motion located further away from the wall. The unexpected behaviour of the fluxes and of the turbulent generation mechanisms may have strong repercussions on both theoretical and modelling approaches to wall turbulence. Indeed, actual turbulent flows are shown here to have a much richer physics with respect to the classical notion of turbulent cascade, where anisotropic production and inhomogeneous fluxes lead to a complex redistribution of energy where a spatial reverse cascade plays a central role.

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Subgrid-scale energy transfer and near-wall turbulence structure

Cited by 120 publications

References 19 publications

The role of coherent structures in subgrid-scale energy transfer within the log layer of wall turbulence

The role of coherent structures in subgrid-scale energy transfer within the log layer of wall turbulence

On the effects of nonequilibrium on the subgrid-scale stresses

Cascades and wall-normal fluxes in turbulent channel flows

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