Probability density function of turbulent velocity fluctuations in a rough-wall boundary layer.
The probability density function of single-point velocity fluctuations in turbulence is studied systematically using Fourier coefficients in the energy-containing range. In ideal turbulence where energy-containing motions are random and independent, the Fourier coefficients tend to Gaussian and independent of each other. Velocity fluctuations accordingly tend to Gaussian. However, if energy-containing motions are intermittent or contaminated with bounded-amplitude motions such as wavy wakes, the Fourier coefficients tend to non-Gaussian and dependent of each other. Velocity fluctuations accordingly tend to non-Gaussian. These situations are found in our experiment of a rough-wall boundary layer.
Mouri
Hideaki
H
Meteorological Research Institute, Nagamine 1-1, Tsukuba 305-0052, Japan. hmouri@mri-jma.go.jp
Takaoka
Masanori
M
Hori
Akihiro
A
Kawashima
Yoshihide
Y