Re-evaluating wake width in turbulent shear flow behind an axisymmetric cylinder by means of higher order turbulence statistics

Abstract

The free turbulent shear flow behind a long axisymmetric cylinder, i.e., a wake, is two-dimensional in nature and is composed of inner shear turbulence and outer potential, irrotational flow (free stream) regions. The conventional definitions of wake width, l_u, are based on the mean velocity field, namely, the first order statistic of turbulence. Two alternative definitions of wake width, l_S = 2_yS and l_F = 2_yF, are proposed in terms of skewnes and flatness factors, respectively, which are considered as third- and fourth-order statistics of turbulence in this study. Between these two new definitions of wake width, l_F can represent a more proper sectional range of shea turbulence in a wake.