Law of bounded dissipation and its consequences in turbulent wall flows

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Abstract

The dominant paradigm in turbulent wall flows is that the mean velocity near the wall, when scaled on wall variables, is independent of the friction Reynolds number. This paradigm faces challenges when applied to fluctuations but has received serious attention only recently. Here, by extending our earlier work (Chen & Sreenivasan, J. Fluid Mech., vol. 908, 2021, p. R3) we present a promising perspective, and support it with data, that fluctuations displaying non-zero wall values, or near-wall peaks, are bounded for large values of, owing to the natural constraint that the dissipation rate is bounded. Specifically, where represents the maximum value of any of the following quantities: energy dissipation rate, turbulent diffusion, fluctuations of pressure, streamwise and spanwise velocities, squares of vorticity components, and the wall values of pressure and shear stresses; the subscript denotes the bounded asymptotic value of, and the coefficient depends on but not on. Moreover, there exists a scaling law for the maximum value in the wall-normal direction of high-order moments, of the form, where represents the streamwise or spanwise velocity fluctuation, and and are independent of. Excellent agreement with available data is observed. A stochastic process for which the random variable has the form just mentioned, referred to here as the 'linear -norm Gaussian', is proposed to explain the observed linear dependence of on.

Original languageEnglish (US)
Article numberA20
JournalJournal of Fluid Mechanics
Volume933
DOIs
StatePublished - Feb 25 2022

Keywords

  • pipe flow boundary layer
  • turbulence theory
  • turbulent boundary layers

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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