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Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

TURBULENCE STRUCTURE AND TRANSPORT MECHANISM IN A HOMOGENEOUS SHEAR FLOW (REYNOLDS NUMBER EFFECTS)

M. Iwatsuki
Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Oaki Iida
Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan

Yasutaka Nagano
Nagoya Industrial Science Research Institute; Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Abstract

Direct numerical simulations (DNS) are carried out to investigate the kinematics of vortical structures in a ho-mogeneous shear flow. Generated longitudinal (streamwise) vortices are conditionally averaged over all the computational region. The effects of the non-linear term on their kinematics are investigated by comparing the DNS and Rapid Distortion Theory (RDT) in both high and low Reynolds number flow fields. It is found that the strain rates in the vortical structure are generated by the effects of the non-linear term and closely associated with the kinematics of the vortical structure. As the Reynolds number increases, the wrapping of the streamwise velocity fluctuation around the vortex is more enhanced to augment the strain rate inside the vortex.