• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1073-1084
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• 1999

The effects of secondary flow on the structure of a turbulent wake generated by a flat plate was investigated experimentally. The secondary flow was induced In a $90^{\circ}$ curved duct in which the flat plate wake generator was installed. The wake generator was installed in such a way that the wake velocity gradient exists in the span wise direction of the curved duct. Measurements were made in the plane containing the mean radius of curvature where pressure gradient and curvature effects were small compared with the secondary flow effect. All six components of the Reynolds stresses were measured in the curved duct. Turbulence intensities in the curved wake are higher than those in the straight wake due to an increase of the turbulent kinetic energy production by the secondary flow. In the inner wake region, shear stress and strain in the plane containing the velocity gradient of the wake show opposite signs with respect to each other, so that eddy viscosity Is negative in this region. This indicates that gradient-diffusion type turbulence models are not appropriate to simulate this type of flow.