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

oleh: Kuan-Huang LEE, Keh-Chin CHANG

Format: Article
Diterbitkan: The Japan Society of Mechanical Engineers 2014-09-01

Deskripsi

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, lu, are based on the mean velocity field, namely, the first order statistic of turbulence. Two alternative definitions of wake width, lS = 2yS and lF = 2yF, 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, lF can represent a more proper sectional range of shea turbulence in a wake.