Temporal and spatial intermittencies within Newtonian turbulence

Abstract eng:
Direct numerical simulations of a pressure driven turbulent flow are performed in a large rectangular channel. Extreme and moderate drag regimes within turbulence that have earlier been found to exist temporally in minimal channels at low Reynolds numbers have been observed both spatially and temporally in full-size turbulent flows. These intermittent regimes, namely, “hyperactive”, “active” and “hibernating” turbulence, display very different structural and statistical features. Using conditional sampling, we identify these intermittent intervals and present the differences between them in terms of simple quantities like mean velocity, wall shear stress and flow structures. By conditionally sampling of the low wall shear stress events in particular, we show that a Newtonian trajectory in large domains occasionally

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