Physics of Fluids - Publications

Scaling of maximum probability density function of velocity increments in turbulent Rayleigh-Bénard convection

Journal of Hydrodynamics 26, 351 – 362 (2014)

Authors

	Xiang Qiu
	Yongxiang Huang
	Quan Zhou
	Chao Sun

BibTeΧ

@article{QIU2014351,
title = "Scaling of maximum probability density function of velocity increments in turbulent Rayleigh-Bénard convection ",
journal = "Journal of Hydrodynamics, Ser. B ",
volume = "26",
number = "3",
pages = "351 - 362",
year = "2014",
note = "",
issn = "1001-6058",
doi = "http://dx.doi.org/10.1016/S1001-6058(14)60040-8",
url = "http://www.sciencedirect.com/science/article/pii/S1001605814600408",
author = "Xiang QIU and HUANG Yong-xiang and Quan ZHOU and Chao SUN",
keywords = "Rayleigh-Bénard convection",
keywords = "scaling",
keywords = "probability density function (pdf) ",
abstract = "Abstract In this paper, we apply a scaling analysis of the maximum of the probability density function (pdf) of velocity increments, i.e., p max ( τ ) = max Δ u τ p ( Δ u τ ) − τ − α , for a velocity field of turbulent Rayleigh-Bénard convection obtained at the Taylor-microscale Reynolds number Reλ≈60. The scaling exponent is comparable with that of the first-order velocity structure function, ζ(1), in which the large-scale effect might be constrained, showing the background fluctuations of the velocity field. It is found that the integral time T(x/D) scales as T(x/D)-(x/D)-β, with a scaling exponent β=0.25±0.01, suggesting the large-scale inhomogeneity of the flow. Moreover, the pdf scaling exponent α(x,z) is strongly inhomogeneous in the x (horizontal) direction. The vertical-direction-averaged pdf scaling exponent α ˜ ( x , z ) obeys a logarithm law with respect to x, the distance from the cell sidewall, with a scaling exponent ξ≈0.22 within the velocity boundary layer and ξ≈0.28 near the cell sidewall. In the cell's central region, α(x,z) fluctuates around 0.37, which agrees well with ζ(1) obtained in high-Reynolds-number turbulent flows, implying the same intermittent correction. Moreover, the length of the inertial range represented in decade T ˜ I ( x ) is found to be linearly increasing with the wall distance with an exponent 0.65±0.05. "
}