We address the issue of the generation mechanism of near-wall reverse flow (NWRF) events in a fully developed turbulent duct flow using direct numerical simulations and particle image velocimetry at a relatively low Reynolds number. The analysis demonstrates the existence of a large-scale high-momentum flow structure originating upstream of a NWRF region. We propose a conceptual model of the NWRF formation and suggest that they are caused by intensive hairpin vortices incipient at the interface between large-scale high-and low-momentum flow regions identified using a conditional averaging procedure. The similarity of a flow topology associated with the NWRF region for with those for (Chin et al., Phys. Rev. Fluids, vol. 3, issue 11, 2018, p. 114607) and (Cardesa et al., J. Fluid Mech., vol. 880, 2019) indicates the generality of the proposed mechanism.
Предметные области OECD FOS+WOS
- 2.05 ТЕХНОЛОГИЯ МАТЕРИАЛОВ
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