Large-eddy simulation of large-scale structures in long channel flow

By D. Chung, B. McKeon. Journal of Fluid Mechanics, 2010

180 citations recorded by the source corpus.

We investigate statistics of large-scale structures from large-eddy simulation (LES) of turbulent channel flow at friction Reynolds numbers Reτ = 2K and 200K (where K denotes 1000). In order to capture the behaviour of large-scale structures properly, the channel length is chosen to be 96 times the channel half-height. In agreement with experiments, these large-scale structures are found to give rise to an apparent amplitude modulation of the underlying small-scale fluctuations. This effect is explained in terms of the phase relationship between the large- and small-scale activity. The shape of the dominant large-scale structure is investigated by conditional averages based on the large-scale velocity, determined using a filter width equal to the channel half-height. The conditioned field demonstrates coherence on a scale of several times the filter width, and the small-scale–large-scale relative phase difference increases away from the wall, passing through π/2 in the overlap region of the mean velocity before approaching π further from the wall. We also found that, near the wall, the convection velocity of the large scales departs slightly, but unequivocally, from the mean velocity.

Subfields: Computational Mechanics, Fluid Flow and Transfer Processes

View Paper: https://www.semanticscholar.org/paper/f6a5771410bca7a8a08ea65577781e1ecb45436e

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Citations in the corpus

The engine behind (wall) turbulence: perspectives on scale interactions (2017, background): “For a periodic signal, R can be simply interpreted as a measure of the relative phase between uL and s (Chung & McKeon 2010), explicitly the cosine of the phase between them.”
Towards Reconciling the Large-Scale Structure of Turbulent Boundary Layers in the Atmosphere and Laboratory (2012, background): “This modulation has also been observed in LES of turbulent channel flow (Chung and McKeon 2010) and in the ASL (Guala et al. 2011).”
Very-large-scale motions in a turbulent boundary layer (2010, result): “These results are consistent with the LES data for a turbulent channel flow obtained by Chung & McKeon (2010).”
Model-based scaling of the streamwise energy density in high-Reynolds-number turbulent channels (2013, background): “…and the large scale velocity signal (identified via filtering in spectral space), which has been interpreted as an amplitude modulation of the small scales, has been investigated in detail, see e.g. Hutchins & Marusic (2007b); Mathis et al. (2009a,b); Chung & McKeon (2010); Hutchins et al. (2011).”
Amplitude modulation of all three velocity components in turbulent boundary layers (2014, methodology): “A similar ensemble averaged map of the small-scale variance conditioned on a large-scale negative streamwise fluctuation is given by Bandyopadhyay & Hussain (1984) and by Chung & McKeon (2010).”
A critical-layer framework for turbulent pipe flow (2010, background): “The conditionally averaged cross-stream streamlines and swirl distributions of Hutchins & Marusic (2007b) and Chung & McKeon (2010) confirm that this is the expected shape for the VLSMs in channel flows.”
On coherent structure in wall turbulence (2013, methodology): “All modes travel at the same convective velocity and we have chosen a priori a phase lag of π/2 for the VLSM relative to the envelope of the small-scale activity at the critical layer, based on observations of real flows (Chung & McKeon 2010; Hutchins et al. 2011).”
Three-dimensional conditional structure of a high-Reynolds-number turbulent boundary layer (2011, background): “A similar relationship between the large-scale velocity gradient and the small-scale fluctuations has been observed in LES of turbulent channel flow (Chung & Mckeon 2010).”
Large eddy simulation with modeled wall-stress: recent progress and future directions (2016, background): “…the outer layer are known to deeply penetrate into the near-wall region (De Graaff & Eaton, 2000; Hutchins & Marusic, 2007) and influence significantly the near-wall flow through an apparent amplitude modulation of the underlying smallscale fluctuations (Mathis et al., 2009; Chung & McKeon, 2010).”