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Small-scale turbulence characteristics of two-dimensional bluff body wakes

Published online by Cambridge University Press:  17 June 2002

R. A. ANTONIA
Affiliation:
Department of Mechanical Engineering, University of Newcastle, NSW, 2308, Australia
T. ZHOU
Affiliation:
Department of Mechanical & Production Engineering, Nanyang Technological University, Singapore 639798
G. P. ROMANO
Affiliation:
Dipartimento di Meccanica e Aeronautica, Universita Degli Studi di Roma “La Sapienza”, 00184 Rome, Italy

Abstract

Measurements have been made in nominally two-dimensional turbulent wakes generated by five different bluff bodies. Each wake has a different level of large-scale organization which is reflected in different amounts of large-scale anisotropy. Structure functions of streamwise (u) and lateral (v) velocity fluctuations at approximately the same value of Rλ, the Taylor microscale Reynolds number, indicate that inertial-range scales are significantly affected by the large-scale anisotropy. The effect is greater on v than u and more pronounced for the porous-body wakes than the solid-body wakes. In particular, ‘relative’ values of the scaling (or power-law) exponents indicate that the magnitude of the transverse exponents can exceed that of the longitudinal ones in the porous-body wakes. This is supported by the inertial-range behaviour of the spectra of u and v. The difference between the transverse and longitudinal exponents appears to depend on the large-scale anisotropy of the flow, as measured by the ratio of the variances of v and u and ratio of the integral length scales of v and u. The spanwise vorticity spectra are much less affected by the anisotropy than the spectra of u and v.

Type
Research Article
Copyright
© 2002 Cambridge University Press

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