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SPATIAL DISTRIBUTION OF ENERGY DISSIPATION IN A TURBULENT CYLINDER WAKE

Jiangang Chen
Institute for Turbulence-Noise-Vibration Interactions and Control Harbin Institute of Technology (Shenzhen) Shenzhen 518055, China

Yu Zhou
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong; Institute for Turbulence-Noise-Vibration Interaction and Control Shenzhen Graduate School, Harbin Institute of Technology Shenzhen, 518055, China

Robert Anthony Antonia
Discipline of Mechanical Engineering, University of Newcastle, Newcastle, 2308, NSW, AUSTRALIA

Tongming Zhou
School of Civil and Resource Engineering, The University of Western Australia 35 Stirling Highway, Crawley, WA6009, Western Australia, Australia

Sinopsis

This work aims to improve our understanding of the turbulent energy dissipation rate in the turbulent wake of a circular cylinder. Ten of the twelve velocity derivative terms which make up the energy dissipation rate are simultaneously obtained with a probe composed of four Xwires. Measurements are made in the plane of mean shear at x/d = 10, 20 and 40, where x is the streamwise distance from the cylinder axis and d is the cylinder diameter, at a Reynolds number of 2.5×103 based on d and free-stream velocity. A phase-averaging technique is used to separate the coherent and remaining structures of the velocity derivatives and the energy dissipation rate ε, approximated by a surrogate based on the assumption of homogeneity in the transverse plane. It is found that the velocity derivatives (∂u/∂y) and (∂v/∂x) play an important role in the interaction between large- and small- scale turbulent structures. The phase-averaged data indicate that energy dissipation occurs spatially mostly within the coherent spanwise vortices, rather than in the regions of turbulent mixing as described by in the widely accepted flow structure model (Hussain and Hayakawa, 1986, 1987). A revised model is proposed to reflect the present finding on the spatial distribution of the energy dissipation rate.